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Thöle M, Brezina T. Thyroid Disease in Rabbits and Rodents. Vet Clin North Am Exot Anim Pract 2024:S1094-9194(24)00041-0. [PMID: 39266375 DOI: 10.1016/j.cvex.2024.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/14/2024]
Abstract
While thyroid disease is generally uncommon in rabbits and rodents, it is most frequently diagnosed in guinea pigs. Particularly, hyperthyroidism and thyroid neoplasms are diagnosed regularly in this species, while thyroid neoplasia is the most common thyroid disorder found in other rodents. Thyroid disease appears to be rare in rabbits, though modalities to reliably diagnose different disorders like hypothyroidism are currently lacking.
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Affiliation(s)
- Milena Thöle
- Tierklinik Posthausen, Rothlaker Str. 1, Posthausen 28870, Germany.
| | - Tina Brezina
- Zentrum für Tiergesundheit, Im Rollfeld 58, Baden Baden 76532, Germany
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Stammeleer L, Xifra P, Serrano SI, Rishniw M, Daminet S, Peterson ME. Blood pressure in hyperthyroid cats before and after radioiodine treatment. J Vet Intern Med 2024; 38:1359-1369. [PMID: 38440934 PMCID: PMC11099771 DOI: 10.1111/jvim.17032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 02/16/2024] [Indexed: 03/06/2024] Open
Abstract
BACKGROUND Hyperthyroid cats commonly have systemic hypertension, with a reported prevalence of 7% to 48%. Although hypertension might be expected to resolve once treatment restores euthyroidism, it can persist or only first develop after treatment. OBJECTIVES To determine the proportion of hyperthyroid cats with hypertension (systolic blood pressure [SBP] ≥160 mm Hg), persistence or first development of hypertension after successful radioiodine treatment, and correlation of post-treatment hypertension with azotemia or hypothyroidism. ANIMALS Four hundred one hyperthyroid nonazotemic cats were included in the study. METHODS Prospective, cross-sectional and before-and-after studies. All hyperthyroid cats had SBP measured by Doppler; 255 had SBP rechecked 6 months after successful radioiodine (131I) treatment. RESULTS Of untreated hyperthyroid cats, 108/401 (27%) were hypertensive. A higher proportion of hypertensive cats were nervous/excited compared with normotensive cats (47% vs 12%; P < .001). Of the initially hypertensive cats, 87/108 cats were reexamined after 131I treatment; 43/87 (49%) cats normalized SBP, whereas 44/87 (51%) remained hypertensive. Of the initially normotensive cats, 16/168 (9.5%) first developed hypertension after successful 131I treatment. 7/60 (12%) of the 131I-treated hypertensive cats were azotemic and 9/60 (15%) were hypothyroid. A higher proportion of cats remaining hypertensive had nervous/excited demeanor than did normotensive cats (50% vs 17%; P < .001). CONCLUSIONS/CLINICAL IMPORTANCE Hypertension, when present, resolves in many hyperthyroid cats after successful treatment. Hyperthyroid cats uncommonly develop new hypertension after treatment. Persistent or newly detected hypertension was unrelated to azotemia or iatrogenic hypothyroidism. More frequently perceived nervousness/anxiety in radioiodine-treated hypertensive cats suggests that many of these cats might have "situational" hypertension, as hyperthyroid-induced hypertension should resolve after treatment.
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Affiliation(s)
- Lisa Stammeleer
- Small Animal Department, Faculty of Veterinary MedicineGhent UniversityMerelbekeBelgium
| | | | | | | | - Sylvie Daminet
- Small Animal Department, Faculty of Veterinary MedicineGhent UniversityMerelbekeBelgium
| | - Mark E. Peterson
- Cornell UniversityIthacaNew YorkUSA
- Animal Endocrine ClinicNew YorkNew YorkUSA
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Moreno D, Cosford K, Snead E, Carr A. Assessment of hemostasis in hyperthyroid and euthyroid cats using two viscoelastic assays and platelet aggregometry. J Vet Intern Med 2024; 38:1377-1383. [PMID: 38465916 PMCID: PMC11099719 DOI: 10.1111/jvim.17038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Accepted: 02/27/2024] [Indexed: 03/12/2024] Open
Abstract
BACKGROUND Hyperthyroidism in humans is associated with a hypercoagulable state and an increased risk of thromboembolism. OBJECTIVE To evaluate hemostatic variables in hyperthyroid and euthyroid cats with the hypothesis that hyperthyroid cats will have evidence of altered hemostasis consistent with a potential hypercoagulable state. ANIMALS Client-owned hyperthyroid (n = 16) and euthyroid (n = 15) cats over 8 years of age. METHODS Prospective observational study. Hyperthyroid and euthyroid cats were enrolled. Rotational thromboelastometry (ROTEM), whole-blood platelet impedance aggregometry (WBPIA) and a point-of-care viscoelastic coagulation monitor (VCM-Vet) were performed immediately after minimally traumatic venipuncture under sedation. RESULTS Hyperthyroid cats had significantly higher values for variables as assessed by VCM-Vet: A10 (34 [17-47] vs 25 [17-38], P = .003); A20 (39.5 [23-55] vs 31 [21-45], P = .003); and MCF (41 [24-58] vs 35 [22-49], P = .03). Hyperthyroid cats had significantly different values versus the euthyroid cohort as assessed by different ROTEM channels: increased A10, INTEM (61.5 [39-75] vs 54 [23-66], P = .007) and FIBTEM (18 [10-35] vs 13 [2-27], P = .01); increased A20, INTEM (68 [45-78] vs 61 [30-70], P = .006) and FIBTEM (17 [10-34] vs 11 [2-25], P = .002); increased MCF, EXTEM (72 [65-81] vs 69 [34-78], P = .04), INTEM (70 [45-85] vs 62 [35-71], P = .01) and FIBTEM (18 [13-37] vs 14 [3-27], P = .02); increased alpha angle, EXTEM (80 [68-85] vs 76 [41-84], P = .01); shortened CT, EXTEM (52.5 [29-73] vs 60 [52-92], P = .003) and FIBTEM (52.5 [16-75] vs 65 [53-165], P = .001); and decreased ML, FIBTEM (20 [1-36] vs 33 [19-59], P <.001). No significant differences were found with WBPIA. CONCLUSIONS AND CLINICAL IMPORTANCE The hyperthyroid cats in this study had evidence of altered hemostasis as assessed by 2 viscoelastic methodologies, and characterized by increased clot amplitude, firmness, and faster coagulation times vs euthyroid controls.
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Affiliation(s)
- Daniel Moreno
- Department of Small Animal Clinical SciencesWestern College of Veterinary Medicine, University of SaskatchewanSaskatoonCanada
| | - Kevin Cosford
- Department of Small Animal Clinical SciencesWestern College of Veterinary Medicine, University of SaskatchewanSaskatoonCanada
| | - Elisabeth Snead
- Department of Small Animal Clinical SciencesWestern College of Veterinary Medicine, University of SaskatchewanSaskatoonCanada
| | - Anthony Carr
- Department of Small Animal Clinical SciencesWestern College of Veterinary Medicine, University of SaskatchewanSaskatoonCanada
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Peterson ME, Rishniw M. Urine concentrating ability in cats with hyperthyroidism: Influence of radioiodine treatment, masked azotemia, and iatrogenic hypothyroidism. J Vet Intern Med 2023; 37:2039-2051. [PMID: 37668163 PMCID: PMC10658547 DOI: 10.1111/jvim.16849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 08/23/2023] [Indexed: 09/06/2023] Open
Abstract
BACKGROUND Hyperthyroid cats often have urine specific gravity (USG) values <1.035. It remains unclear how USG changes after treatment, if USG can be used to predict azotemia after treatment, or how iatrogenic hypothyroidism influences USG values. OBJECTIVES To determine the proportion of hyperthyroid cats with USG <1.035 vs ≥1.035; if USG changes after treatment; and whether USG <1.035 correlated with unmasking of azotemia or hypothyroidism. ANIMALS Six hundred fifty-five hyperthyroid cats treated with radioiodine; 190 clinically normal cats. METHODS Prospective, before-and-after study. Hyperthyroid cats had serum thyroxine, thyroid-stimulating hormone, and creatinine concentrations, and USG measured before and 6 months after successful treatment with radioiodine. RESULTS Of untreated hyperthyroid cats, USG was ≥1.035 in 346 (52.8%) and <1.035 in 309 (47.2%). After treatment, 279/346 (80.6%) maintained USG ≥1.035, whereas 67/346 (19.4%) became <1.035; 272/309 (88%) maintained USG <1.035, whereas 37/309 (12%) became ≥1.035. Only 22/346 (6.4%) with USG ≥1.035 developed azotemia after treatment, compared with 136/309 (44%) with <1.035 (P < .001). Of cats remaining nonazotemic, 38% had USG <1.035, compared with 20% of normal cats (P < .001). The 137 cats with iatrogenic hypothyroidism had lower USG after treatment than did 508 euthyroid cats (1.024 vs 1.035), but USGs did not change after levothyroxine supplementation. USG <1.035 had high sensitivity (86.1%) but moderate specificity (65.2%) in predicting azotemia after treatment. CONCLUSIONS AND CLINICAL IMPORTANCE Hyperthyroidism appears not to affect USG in cats. However, cats with evidence of sub-optimal concentrating ability before radioiodine treatment (USG < 1.035) are more likely to develop azotemia and unmask previously occult chronic kidney disease. Iatrogenic hypothyroidism itself did not appear to affect USG values.
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Affiliation(s)
- Mark E. Peterson
- Animal Endocrine Clinic, 21 West 100th StreetNew YorkNew YorkUSA
- College of Veterinary MedicineCornell UniversityIthacaNew YorkUSA
| | - Mark Rishniw
- College of Veterinary MedicineCornell UniversityIthacaNew YorkUSA
- Veterinary Information NetworkDavisCaliforniaUSA
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Kang S, Koo Y, Yun T, Chae Y, Lee D, Kim H, Yang MP, Kang BT. Use of 18 F-2-deoxy-2-fluoro-D-glucose positron emission tomography/computed tomography for staging thyroid carcinoma in a cat. Vet Med Sci 2023; 9:1026-1030. [PMID: 36913242 DOI: 10.1002/vms3.1106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 01/24/2023] [Accepted: 02/06/2023] [Indexed: 03/14/2023] Open
Abstract
Thyroid nodules are common in older cats and are mostly benign; however, carcinomas may occur infrequently. In cats, thyroid carcinomas tend to be highly metastatic. The role of 18 F-2-deoxy-2-fluoro-D-glucose (FDG) positron emission tomography (PET)/computed tomography (CT) in human thyroid carcinoma has been well established. However, guidelines have not yet been established for veterinary medicine. Metastasis assessment has typically been performed using CT in veterinary medicine; however, it is poorly sensitive in detecting regional lymph nodes or distant metastases if these lesions are not abnormally contrast-enhanced, enlarged or cause overt mass effects. This case suggested that FDG PET/CT may be used for staging feline thyroid carcinoma, and the results contributed to treatment recommendations.
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Affiliation(s)
- Seonggweon Kang
- Laboratory of Veterinary Internal Medicine, College of Veterinary Medicine, Chungbuk National University, Cheongju, Republic of Korea
| | - Yoonhoi Koo
- Laboratory of Veterinary Internal Medicine, College of Veterinary Medicine, Chungbuk National University, Cheongju, Republic of Korea
| | - Taesik Yun
- Laboratory of Veterinary Internal Medicine, College of Veterinary Medicine, Chungbuk National University, Cheongju, Republic of Korea
| | - Yeon Chae
- Laboratory of Veterinary Internal Medicine, College of Veterinary Medicine, Chungbuk National University, Cheongju, Republic of Korea
| | - Dohee Lee
- Laboratory of Veterinary Internal Medicine, College of Veterinary Medicine, Chungbuk National University, Cheongju, Republic of Korea
| | - Hakhyun Kim
- Laboratory of Veterinary Internal Medicine, College of Veterinary Medicine, Chungbuk National University, Cheongju, Republic of Korea
| | - Mhan-Pyo Yang
- Laboratory of Veterinary Internal Medicine, College of Veterinary Medicine, Chungbuk National University, Cheongju, Republic of Korea
| | - Byeong-Teck Kang
- Laboratory of Veterinary Internal Medicine, College of Veterinary Medicine, Chungbuk National University, Cheongju, Republic of Korea
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Miceli DD, García JD, Rey Amunategui JP, Pompili GA, Rial LA, Más J, Molina EM, Pignataro OP. Prevalence of hypersomatotropism and hyperthyroidism in cats with diabetes mellitus from referral centers in Buenos Aires (2020-2022). J Feline Med Surg 2023; 25:1098612X221148565. [PMID: 36779783 PMCID: PMC10812081 DOI: 10.1177/1098612x221148565] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
OBJECTIVES The aim of this study was to estimate the prevalence of hypersomatotropism (HST) and hyperthyroidism in cats with diabetes mellitus (DM) from referral centers in Buenos Aires, Argentina. METHODS This was a prospective study. Systematic screening of serum insulin-like growth factor 1 (IGF-1) and total thyroxine was performed in all cats diagnosed with DM at referral centers in Buenos Aires between February 2020 and February 2022. RESULTS In total, 154 diabetic cats were evaluated (99 males and 55 females; median age 12 years [range 3-21]; mean body weight 5 kg [range 2-12]). Altogether, there were 115 (75%) domestic shorthairs and one domestic longhair; the remaining 38 cats were purebred (mainly Siamese, n = 25 [16%]). Twenty (12.9%) cats had IGF-1 concentrations >1000 ng/ml, and three (1.9%) had IGF-1 concentrations between 800 and 1000 ng/ml along with pituitary enlargement on CT, resulting in a 14.9% HST prevalence rate in diabetic cats. Intracranial imaging was performed in all cats with HST; median pituitary dorsoventral height was 5.8 mm (range 3.1-9.5). Fourteen of 23 (61%) cats had phenotypic changes consistent with acromegaly at the time of diagnosis of HST. Four of 154 (2.5%) cats had concurrent hyperthyroidism. CONCLUSIONS AND RELEVANCE To date, this is the first study outside of Europe to have evaluated the prevalence of HST and hyperthyroidism in cats with DM. In Buenos Aires referral centers, feline HST is the most common concurrent endocrinopathy in cats with DM but with a lower prevalence than has previously been reported. Hyperthyroidism is a rare concurrent endocrinopathy in diabetic cats from referral centers in Buenos Aires.
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Affiliation(s)
- Diego D Miceli
- Laboratory of Molecular Endocrinology and Signal Transduction, Institute of Experimental Biology and Medicine – CONICET, Buenos Aires, Argentina
- Veterinary Science Center, Maimonides University, Buenos Aires, Argentina
| | - Jorge D García
- Hospital School of Veterinary Medicine, University of Buenos Aires, Faculty of Veterinary Sciences, Buenos Aires, Argentina
| | | | - Gustavo A Pompili
- Hospital School of Veterinary Medicine, University of Buenos Aires, Faculty of Veterinary Sciences, Buenos Aires, Argentina
| | - Laura A Rial
- Department of Animal Welfare and Ethology, University of Buenos Aires, Faculty of Veterinary Sciences, Buenos Aires, Argentina
| | - Javier Más
- Diagnotest Laboratory, Buenos Aires, Argentina
| | - Estela M Molina
- Hospital School of Veterinary Medicine, University of Buenos Aires, Faculty of Veterinary Sciences, Buenos Aires, Argentina
| | - Omar P Pignataro
- Laboratory of Molecular Endocrinology and Signal Transduction, Institute of Experimental Biology and Medicine – CONICET, Buenos Aires, Argentina
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Xifra P, Serrano SI, Peterson ME. Effect of radioiodine treatment on muscle mass in hyperthyroid cats. Vet Med (Auckl) 2022; 36:1931-1941. [PMID: 36200596 DOI: 10.1111/jvim.16560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 09/21/2022] [Indexed: 11/26/2022]
Abstract
BACKGROUND Approximately 75% of hyperthyroid cats lose muscle mass as accessed with a muscle condition scoring (MCS) system. After treatment, MCS improves as the cats regain muscle mass. OBJECTIVES To quantify the degree of muscle loss in hyperthyroid cats using ultrasonography and evaluate changes in muscle mass after treatment. ANIMALS Forty-eight clinically normal cats and 120 cats with untreated hyperthyroidism, 75 of which were reevaluated after radioiodine-131 therapy. METHODS Prospective cross-sectional and before-after studies. All cats underwent ultrasonography and measurement of epaxial muscle height (EMH), with subsequent calculation of vertebral and forelimb epaxial muscle scores (VEMS and FLEMS). A subset of hyperthyroid cats underwent repeat muscle imaging 6 months after treatment. RESULTS Untreated hyperthyroid cats had a lower EMH than did clinically normal cats (median [25th-75th percentile], 0.98 [0.88-1.16] cm vs 1.34 [1.23-1.58] cm, P < .001). Seventy-seven (64.2%) untreated cats had subnormal EMH. Similarly, compared to normal cats, hyperthyroid cats had lower VEMS (0.93 [0.84-1.07] vs 1.27 [1.18-1.39], P < .001) and FLEMS (1.24 [1.10-1.35] vs 1.49 [1.39-1.63], P < .001). After treatment, EMH increased (1.03 [0.89-1.03] cm to 1.33 [1.17-1.41] cm, P < .001), with abnormally low EMH normalizing in 36/41 (88%). Both VEMS (0.94 [0.87-1.10] to 1.21 [1.10-1.31], P < .001) and FLEMS (1.31 [1.17-1.40] to 1.47 [1.38-1.66], P < .001) also increased after treatment. CONCLUSIONS AND CLINICAL IMPORTANCE Almost two-thirds of hyperthyroid cats have abnormally low muscle mass when measured quantitatively by ultrasound. Successful treatment restores muscle mass in >85% of cats. EMH provided the best means of quantitating muscle mass in these cats.
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Affiliation(s)
| | | | - Mark E Peterson
- Animal Endocrine Clinic, NYC, New York, New York, USA.,College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
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Yu L, Lacorcia L, Johnstone T. Hyperthyroid cats and their kidneys: a literature review. Aust Vet J 2022; 100:415-432. [PMID: 35711100 PMCID: PMC9543258 DOI: 10.1111/avj.13179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Revised: 04/28/2022] [Accepted: 05/01/2022] [Indexed: 11/28/2022]
Abstract
Hyperthyroidism and chronic kidney disease (CKD) are common diseases of geriatric cats, and often occur concurrently. Thus, a thorough understanding of the influence of thyroid function on renal function is of significant value for all feline practitioners. Among other effects, hyperthyroidism causes protein catabolism and increases renal blood flow and glomerular filtration rate (GFR). These effects render traditional renal markers insensitive for the detection of CKD in cats with uncontrolled hyperthyroidism. Furthermore, the development of iatrogenic hypothyroidism with over treatment of hyperthyroidism can be detrimental to renal function and may negatively affect long-term survival. This review discusses important diagnostic considerations of feline hyperthyroidism, as well as key treatment modalities, with an emphasis on the use of radioiodine and the importance of post treatment monitoring of thyroid and renal parameters. In Australia, a common curative treatment for cats with benign hyperthyroidism (i.e. thyroid hyperplasia or adenoma) is a fixed dose of orally administered radioiodine, regardless of the serum total thyroxine concentration at the time of diagnosis. This review discusses the long term outcomes of this standard of care in comparison with current, relevant research literature from around the world. Finally, this review explores the use of symmetric dimethylarginine (SDMA) in assessing renal function before and after treatment in hyperthyroid cats. SDMA correlates well with GFR and creatinine in non-hyperthyroid cats, but our understanding of its performance in hyperthyroid cats remains in its infancy.
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Affiliation(s)
- L Yu
- Veterinary Referral HospitalDandenongVictoriaAustralia
| | - L Lacorcia
- Veterinary Referral HospitalDandenongVictoriaAustralia
| | - T Johnstone
- Animal Referral Hospital, Essendon Fields72 Hargrave AvenueEssendon FieldsVictoria3041Australia
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Xifra P, Serrano SI, Peterson ME. Radioiodine treatment of hyperthyroidism in cats: results of 165 cats treated by an individualised dosing algorithm in Spain. J Feline Med Surg 2022; 24:e258-e268. [PMID: 35748791 PMCID: PMC10812264 DOI: 10.1177/1098612x221104743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
OBJECTIVES Although radioiodine (131I) is the treatment of choice for feline hyperthyroidism, 131I-dosing protocols commonly induce iatrogenic hypothyroidism and expose azotaemia. A recently reported patient-specific 131I dosing algorithm minimised the risk of 131I-induced hypothyroidism and azotaemia, while maintaining high cure rates. The aim of the study was to report results of 131I treatment in a European population of hyperthyroid cats using this patient-specific dosing algorithm. METHODS This prospective case series (before-and-after study) evaluated 165 hyperthyroid cats referred for 131I treatment. All cats had serum concentrations of thyroxine (T4), triiodothyronine (T3) and thyroid-stimulating hormone (TSH) measured (off methimazole ⩾1 week). Thyroid volume and percentage uptake of 99mTc-pertechnetate (TcTU) were determined using thyroid scintigraphy. An initial 131I dose was calculated by averaging dose scores for T4/T3 concentrations, thyroid volume and TcTU; 70% of that composite dose was then administered. Twenty-four hours later, percentage 131I uptake was measured, and additional 131I administered as needed to deliver an adequate radiation dose to the thyroid tumour(s). Serum concentrations of T4, TSH and creatinine were determined 6-12 months later. RESULTS Median calculated 131I dose was 2.15 mCi (range 1.2-7.5), with only 51 (30.9%) receiving ⩾2.5 mCi. Of 165 cats, 124 (75.2%) became euthyroid, seven (4.2%) became overtly hypothyroid, 27 (16.4%) became subclinically hypothyroid and seven (4.2%) remained hyperthyroid. A higher proportion of overtly (85.7%) and subclinically (26.9%) hypothyroid cats developed azotaemia than euthyroid cats (13.6%; P = 0.0002). Hypothyroid cats were older (P = 0.016) and more likely to have detectable TSH concentrations (P = 0.025) and symmetrical bilateral distribution of 99mTc-pertechnetate uptake (P = 0.0002), whereas persistently hyperthyroid cats had higher severity scores (P = 0.012). CONCLUSIONS AND RELEVANCE Our results confirm that 131I dosing with this new algorithm results in high cure rates, with a lowered prevalence of 131I-induced overt hypothyroidism and azotaemia. Age, serum TSH concentrations, bilateral, symmetrical uptake and severity score help predict outcome.
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Affiliation(s)
| | | | - Mark E Peterson
- Animal Endocrine Clinic, New York, NY, USA
- Cornell University, Ithaca, NY, USA
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Geddes R, Aguiar J. Feline Comorbidities: Balancing hyperthyroidism and concurrent chronic kidney disease. J Feline Med Surg 2022; 24:641-650. [PMID: 35481810 PMCID: PMC11107990 DOI: 10.1177/1098612x221090390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PRACTICAL RELEVANCE Both hyperthyroidism and chronic kidney disease (CKD) are common long-term conditions in older cats, which might be diagnosed concurrently or develop at different times. Hyperthyroidism may mask the presence of CKD, and vice versa, by various mechanisms that are described in this review. Hyperthyroidism treatment options should be carefully considered when CKD has also been diagnosed. CLINICAL CHALLENGES Although it can be difficult to diagnose hyperthyroidism and CKD simultaneously, given that one condition may mask the other, it is important to consider the presence of both diseases when examining an older cat presenting with vomiting, weight loss, polyuria/ polydipsia, anorexia or sarcopenia. The concurrent presence of hyperthyroidism and CKD requires careful monitoring of glomerular filtration rate biomarkers, and adequate and prompt support of kidney function when normal thyroid function is re-established. Iatrogenic hypothyroidism is a recognised complication of all of the treatment options for hyperthyroidism, and increases the risk of azotaemia. Therapy with levothyroxine is recommended for cats that are hypothyroid and azotaemic. EVIDENCE BASE The information in this review draws on current literature and guidelines related to the pathophysiology, diagnosis and treatment recommendations for feline hyperthyroidism and CKD.
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Affiliation(s)
- Rebecca Geddes
- Clinical Sciences and Services, Royal Veterinary College, University of London, London, UK
| | - Joana Aguiar
- Dick White Referrals, Station Farm, London Road, Six Mile Bottom, Cambridgeshire, UK
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Urbanschitz T, Burgener IA, Zeugswetter FK. Utility of a canine TSH assay for diagnosis and monitoring of feline hyperthyroidism. TIERARZTLICHE PRAXIS. AUSGABE K, KLEINTIERE/HEIMTIERE 2022; 50:93-100. [PMID: 35523163 DOI: 10.1055/a-1807-9546] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
OBJECTIVE This retrospective study was initiated to evaluate the utility of TSH measurements using a common canine TSH assay to diagnose and monitor feline hyperthyroidism after radioiodine or thyreostatic drug treatment. MATERIAL AND METHODS The electronic database of the University of Veterinary Medicine Vienna was searched for combined TSH and T4 measurements. 217 pairs of TSH and T4 from 136 cats with possible hyperthyroidism were assigned to group A (untreated; n = 24) and B (treated; n = 193). Measurements in group B were then subcategorized according to T4 concentrations (reference range 15-50 nmol/L): group B1 = elevated T4 (n = 46), group B2 = normal T4 (n = 84) and group B3 = decreased T4 (n = 63). Group B2 was further divided into cats with low normal (group B2a; n = 35), medium normal (group B2b; n = 29) and high normal (group B2c; n = 20) T4 concentrations. RESULTS TSH was detectable in 4 (17 %) of the 24 untreated cats (group A) and did not return to normal despite seemingly successful therapy in two. Increased TSH concentrations were observed in 3.6 % of the treated cats in group B2 and 2.9 %, 6.9 %, and 0 % in subgroups B2a, B2b and B2c, respectively. Forty-four percent of the treated cats with a decreased T4 (group B3) had an increased TSH concentration. TSH correlated with treatment length (r = 0.358, p = 0.004) and was significantly higher in cats treated for more than 3 months (p = 0.008). CONCLUSION TSH was detectable in a significant number of untreated hyperthyroid cats and thus this parameter should not be used to definitively rule out feline hyperthyroidism. Furthermore, the very low prevalence of increased TSH concentrations in treated hyperthyroid cats with a normal T4 and cost benefit calculations do not support the routine measurement of TSH in these cats. The fact that TSH correlated with time since treatment start and 56 % of the cats with a decreased T4 had TSH concentrations within the reference limits, suggests delayed recovery of the pituitary thyrotrophs which might explain the low prevalence of subclinical hypothyroidism in the present study. CLINICAL RELEVANCE TSH measurement in cats with suspected or treated hyperthyroidism using a canine assay lacks diagnostic sensitivity and can only complement therapeutic decision-making.
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Affiliation(s)
| | - Iwan A Burgener
- Department for Small Animals and Horses, University of Veterinary Medicine, Division of small animal internal medicine
| | - Florian K Zeugswetter
- Department for Small Animals and Horses, University of Veterinary Medicine, Division of small animal internal medicine
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Peterson ME, Rishniw M. Predicting outcomes in hyperthyroid cats treated with radioiodine. J Vet Intern Med 2021; 36:49-58. [PMID: 34817910 PMCID: PMC8783366 DOI: 10.1111/jvim.16319] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 11/05/2021] [Accepted: 11/15/2021] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Radioiodine (131 I) is the treatment of choice for cats with hyperthyroidism. After 131 I, however, euthyroidism is not always achieved, with 5% to 10% of cats remaining persistently hyperthyroid and 20% to 50% developing iatrogenic hypothyroidism. OBJECTIVES To identify pretreatment factors that may help predict persistent hyperthyroidism and iatrogenic hypothyroidism after treatment of cats using a novel 131 I dosing algorithm. ANIMALS One thousand and four hundred hyperthyroid cats treated with 131 I. METHODS Prospective, before-and-after study. Pretreatment predictors (clinical, laboratory, scintigraphic, 131 I dose, 131 I uptake measurements) of treatment failure or iatrogenic hypothyroidism were identified by multivariable logistic regression analysis. RESULTS Cats that developed iatrogenic hypothyroidism were more likely to be older (odds ratio [OR] = 1.10; 95% confidence interval [CI], 1.04-1.17; P = .001), female (OR = 2.04; 95% CI, 1.54-2.70; P < .001), have detectable serum thyroid-stimulating hormone (TSH) concentrations (OR = 4.19; 95% CI, 2.0-8.81; P < .001), have bilateral thyroid nodules (OR = 1.57; 95% CI, 1.19-2.08; P < .001), have homogeneous, bilateral distribution of 99m Tc-pertechnetate uptake (OR = 2.93; 95% CI, 2.05-4.19; P < .001), have milder severity score (OR = 0.62; 95% CI, 0.49-0.79; P < .001), and have higher 131 I uptake (OR = 2.40; 95% CI, 1.75-3.28; P < .001). In contrast, cats remaining persistently hyperthyroid were more likely to be younger (OR = 0.81; 95% CI, 0.72-0.92; P < .001), have higher severity score (OR = 1.87; 95% CI, 1.51-2.31; P < .001), and have lower 131 I uptake (OR = 3.50; 95% CI, 1.8-6.80; P < .001). CONCLUSIONS AND CLINICAL IMPORTANCE Age, sex, serum TSH concentration, bilateral and homogeneous 99m Tc-pertechnetate uptake on scintigraphy, severity score, and percent 131 I uptake are all factors that might help predict outcome of 131 I treatment in hyperthyroid cats. Cats with persistent hyperthyroidism had many predictive factors that directly contrasted those of cats that developed 131 I-induced hypothyroidism.
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Affiliation(s)
- Mark E Peterson
- Animal Endocrine Clinic, New York, New York, USA.,College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - Mark Rishniw
- College of Veterinary Medicine, Cornell University, Ithaca, New York, USA.,Veterinary Information Network, Davis, California, USA
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Peterson ME, Rishniw M. A dosing algorithm for individualized radioiodine treatment of cats with hyperthyroidism. J Vet Intern Med 2021; 35:2140-2151. [PMID: 34351027 PMCID: PMC8478068 DOI: 10.1111/jvim.16228] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 07/02/2021] [Accepted: 07/13/2021] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND Radioiodine (131 I) is the treatment of choice for hyperthyroidism in cats, but current 131 I-dosing protocols can induce iatrogenic hypothyroidism and expose azotemia. OBJECTIVES To develop a cat-specific algorithm to calculate the lowest 131 I dose to resolve hyperthyroidism, while minimizing risk of iatrogenic hypothyroidism and subsequent azotemia. ANIMALS One thousand and four hundred hyperthyroid cats treated with 131 I. METHODS Prospective case series (before-and-after study). All cats had serum concentrations of thyroxine (T4 ), triiodothyronine (T3 ), and thyroid-stimulating hormone (TSH) measured (off methimazole ≥1 week). Using thyroid scintigraphy, each cat's thyroid volume and percent uptake of 99m Tc-pertechnatate (TcTU) were determined. An initial 131 I dose was calculated by averaging dose scores for T4 /T3 concentrations, thyroid volume, and TcTU; 80% of that composite dose was administered. Twenty-four hours later, percent 131 I uptake was measured, and additional 131 I administered, as needed, to deliver an adequate radiation dose to the thyroid tumor(s). Serum concentrations of T4 , TSH, and creatinine were determined 6 to 12 months later. RESULTS The median calculated 131 I dose was 1.9 mCi (range, 1.0-10.6 mCi); 1380 cats required additional 131 I administration on day 2. Of the cats, 1047 (74.8%) became euthyroid, 57 (4.1%) became overtly hypothyroid, 240 (17.1%) became subclinically hypothyroid, and 56 (4%) remained hyperthyroid. More overtly (71.9%) and subclinically (39.6%) hypothyroid cats developed azotemia than euthyroid cats (14.2%; P < .0001). CONCLUSIONS AND CLINICAL IMPORTANCE Our algorithm for calculating individual 131 I doses resulted in cure rates similar to historical treatment rates, despite much lower 131 I doses. This algorithm appears to lower prevalence of both 131 I-induced overt hypothyroidism and azotemia.
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Affiliation(s)
- Mark E Peterson
- Animal Endocrine Clinic, New York, New York, USA.,College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - Mark Rishniw
- College of Veterinary Medicine, Cornell University, Ithaca, New York, USA.,Veterinary Information Network, Davis, California, USA
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Mullowney D, Chang YM, Glanemann B, Syme HM. Treatment failure in hyperthyroid cats after radioiodine (I-131) injection. J Vet Intern Med 2021; 35:1688-1696. [PMID: 33999452 PMCID: PMC8295673 DOI: 10.1111/jvim.16161] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Revised: 04/29/2021] [Accepted: 05/03/2021] [Indexed: 12/17/2022] Open
Abstract
Background There is limited published information on the outcome for cats where total thyroxine concentration (TT4) remains elevated after treatment with radioactive iodine (RAI). Objective To determine the frequency of, and predictors for, subsequent treatment failure in cats for which TT4 remains elevated at hospital discharge, and to report clinical outcomes for cats requiring repeat treatment. Animals One hundred twenty‐one cats with TT4 ≥40 nmol/L after treatment with RAI (out of an original, treated study sample of 959 cats). Methods Retrospective study. Data regarding signalment, weight, TT4 concentration (before RAI treatment, at discharge, and percentage change), day of sampling, and I‐131 dose were acquired. Logistic regression was performed to evaluate predictors of treatment failure. Results In the 87 cats for which classification was possible, 35 (40%) became euthyroid without further treatment. All TT4 variables and weight normalized RAI dose were independently predictive of subsequent treatment failure. In multivariate analysis, TT4 concentration at discharge (P < .001) and weight normalized RAI dose (P = .04) remained in the final model. All 28 cats with TT4 concentration ≥150 nmol/L at discharge ultimately failed treatment, compared with 13/40 (32.5%) and 11/19 (57.9%) cats with TT4 concentrations of 40‐100 nmol/L and 100‐150 nmol/L, respectively. Of the 52 cats that failed treatment, 14 were subsequently managed medically, 12 underwent thyroidectomy (4 with carcinoma), 14 had repeat RAI treatment which was successful in 12/14 (86%) cats, and 13 had no further treatment. Conclusions and Clinical Importance Cats with TT4 >150 nmol/L at discharge after RAI might be candidates for immediate repeat treatment.
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Affiliation(s)
- Deirdre Mullowney
- Department of Veterinary Clinical Sciences, Royal Veterinary College, University of London, Hertfordshire AL9 7TA, United Kingdom
| | - Yu-Mei Chang
- Research Support Office, The Royal Veterinary College, London, United Kingdom
| | - Barbara Glanemann
- Department of Veterinary Clinical Sciences, Royal Veterinary College, University of London, Hertfordshire AL9 7TA, United Kingdom
| | - Harriet M Syme
- Department of Veterinary Clinical Sciences, Royal Veterinary College, University of London, Hertfordshire AL9 7TA, United Kingdom
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Argenta FF, de Mello LS, Slaviero M, Cony FG, Bandinelli MB, Pavarini SP, Driemeier D, Sonne L. Pathological and Immunohistochemical Characterization of Thyroid Neoplasms in Cats. J Comp Pathol 2021; 184:44-55. [PMID: 33894877 DOI: 10.1016/j.jcpa.2021.01.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 11/20/2020] [Accepted: 01/28/2021] [Indexed: 10/22/2022]
Abstract
There are few pathological and immunohistochemical descriptions of thyroid neoplasms in cats. We investigated neoplasms of the thyroid in 31 cats (average age 15.6 years) in Southern Brazil. Most (96.8%) of these cases were classified as follicular adenomas and were predominantly unilateral and multinodular. Histologically, macrofollicular adenomas were the most common type observed. Carcinomas represented 3.2% of the investigated tumours. By immunohistochemical labelling, thyroglobulin was expressed more commonly than paired box gene 8 or thyroid transcription factor 1 in the follicular adenomas. One carcinoma was immunopositive for thyroglobulin, pancytokeratin, chromogranin A and synaptophysin, suggestive of a calcitonin-negative neuroendocrine carcinoma.
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Affiliation(s)
- Fernando F Argenta
- Department of Veterinary Pathology, College of Veterinary Medicine, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
| | - Lauren S de Mello
- Department of Veterinary Pathology, College of Veterinary Medicine, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Mônica Slaviero
- Department of Veterinary Pathology, College of Veterinary Medicine, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Fernanda G Cony
- Department of Veterinary Pathology, College of Veterinary Medicine, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Marcele B Bandinelli
- Department of Veterinary Pathology, College of Veterinary Medicine, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Saulo P Pavarini
- Department of Veterinary Pathology, College of Veterinary Medicine, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - David Driemeier
- Department of Veterinary Pathology, College of Veterinary Medicine, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Luciana Sonne
- Department of Veterinary Pathology, College of Veterinary Medicine, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
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Peterson ME. Hyperthyroidism in Cats: Considering the Impact of Treatment Modality on Quality of Life for Cats and Their Owners. Vet Clin North Am Small Anim Pract 2020; 50:1065-1084. [PMID: 32665137 DOI: 10.1016/j.cvsm.2020.06.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In cats, hyperthyroidism can be treated in 4 ways: medical management with methimazole or carbimazole, nutritional management (low-iodine diet), surgical thyroidectomy, and radioactive iodine (131I). Each form of treatment has advantages and disadvantages that should be considered when formulating a treatment plan for the individual hyperthyroid cat. Medical and nutritional managements are considered "reversible" or palliative treatments, whereas surgical thyroidectomy and 131I are "permanent" or curative treatments. The author discusses how each treatment modality could be the optimal choice for a specific cat-owner combination and reviews the advantages and disadvantages of each treatment option.
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Cui Y, Heuser K, Bauer N, Neiger R. Coagulation parameters in hyperthyroid cats before and after radioiodine treatment compared with healthy controls. J Feline Med Surg 2019; 21:1134-1140. [PMID: 30571457 PMCID: PMC10814272 DOI: 10.1177/1098612x18820145] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2024]
Abstract
OBJECTIVES The aim of the study was to describe the coagulatory state of hyperthyroid cats before and after successful radioiodine therapy (RIT) compared with healthy age-matched controls, using classical coagulation parameters and thromboelastogram (TEG) as a global assessment method. The differences in coagulation activity after RIT, depending on the thyroid hormone (normal vs low total thyroxine [T4]) state, were also evaluated. METHODS Fifteen hyperthyroid cats and 10 healthy age-matched controls were recruited. Hyperthyroid cats that remained hyperthyroid 14 days after RIT were excluded. Haematology, biochemistry, T4, prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen and TEG were assessed in control cats and hyperthyroid cats before and 7 and 14 days after RIT. Two weeks after successful RIT, further comparisons were made between cats with normal T4 vs those with low T4. RESULTS Fourteen days after successful RIT, 7/15 cats had normal T4 and 8/15 had low T4. Thrombocytosis was noted in 6/15 cats after treatment. Fibrinogen was significantly higher (P <0.001) and PT shorter (P <0.01) in the hyperthyroid cats compared with the healthy controls and these changes persisted after RIT. Persistent increases in fibrinogen, PT, TEG maximal amplitude and TEG clot rigidity, reflecting clot stability, after RIT primarily occurred in the cats with normal T4. TEG-K (time until preset amplitude of 20 mm is reached) and alpha (α) angle reflected impaired fibrin cross-linking ability prior to RIT, which significantly increased after therapy (P <0.05). CONCLUSIONS AND RELEVANCE Based on some of the coagulation parameters, cats with hyperthyroidism showed hypercoagulable tendencies, which were mildly increased after RIT, possibly due to transient radiation-induced thyroiditis.
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Affiliation(s)
- Yi Cui
- Department of Veterinary Clinical Sciences, Small Animal Internal Medicine, Justus-Liebig University, Giessen, Germany
| | - Katharina Heuser
- Department of Veterinary Clinical Sciences, Small Animal Internal Medicine, Justus-Liebig University, Giessen, Germany
| | - Natali Bauer
- Department of Veterinary Clinical Sciences, Small Animal Internal Medicine, Justus-Liebig University, Giessen, Germany
| | - Reto Neiger
- Small Animal Clinic Hofheim, Hofheim, Germany
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Covey HL, Chang YM, Elliott J, Syme HM. Changes in thyroid and renal function after bilateral thyroidectomy in cats. J Vet Intern Med 2019; 33:508-515. [PMID: 30758070 PMCID: PMC6430951 DOI: 10.1111/jvim.15450] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 01/28/2019] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Iatrogenic hypothyroidism might worsen the prognosis of cats with azotemic CKD after thyroidectomy. Varying thyroxine concentrations influence utility of creatinine in assessing renal function. Symmetric dimethylarginine (SDMA) has limited studies in cats with changing thyroid status. OBJECTIVES Thyroid status is stable 6 months post-thyroidectomy. Symmetric dimethylarginine and creatinine are linearly associated without influence from total thyroxine concentration (tT4). ANIMALS Electronic records of 2 first opinion practices were searched using the term "thyroidectomy" to include 81 client-owned cats that had undergone bilateral thyroidectomy. METHODS Retrospective cross-sectional study assessing thyroid hormone concentrations of 68 cats within 6 months of surgery. A longitudinal study of thyroid status in 23 cats with >18 months follow-up post-thyroidectomy. A generalized estimating equation assessed the associations of bodyweight, tT4 and creatinine concentrations on SDMA concentration. RESULTS Sixty-eight cats had follow-up within 6 months. Fifteen cats (22%) had persistent, or recurrent, hyperthyroidism and 33 cats (49%) were hypothyroid. Twenty-three of the euthyroid/hypothyroid cats had long-term follow-up (595-1955 days); 4 cats (17%) remained hypothyroid, 19 cats (83%) were euthyroid (often transiently), and 9 of 23 cats (44%) developed recurrent hyperthyroidism. Symmetric dimethylarginine and creatinine were linearly associated, but hyperthyroid cats had higher SDMA concentrations, relative to creatinine (P = .003). CONCLUSIONS AND CLINICAL IMPORTANCE Cats have changes in thyroid function for years after bilateral thyroidectomy, with a high incidence of recurrent hyperthyroidism. Both SDMA and creatinine are affected by thyroxine concentrations, and the effect is greater in hyperthyroid cats.
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Affiliation(s)
- Heather L Covey
- Department of Clinical Science and Services, Small Animal Medicine and Surgery Group, The Royal Veterinary College, Hertfordshire, United Kingdom
| | - Yu-Mei Chang
- Research Support Office, The Royal Veterinary College, London, United Kingdom
| | - Jonathan Elliott
- Department of Comparative Biomedical Sciences, The Royal Veterinary College, London, United Kingdom
| | - Harriet M Syme
- Department of Clinical Science and Services, Small Animal Medicine and Surgery Group, The Royal Veterinary College, Hertfordshire, United Kingdom
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Peterson ME, Carothers MA, Gamble DA, Rishniw M. Spontaneous primary hypothyroidism in 7 adult cats. J Vet Intern Med 2018; 32:1864-1873. [PMID: 30294940 PMCID: PMC6271337 DOI: 10.1111/jvim.15239] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 04/10/2018] [Accepted: 05/15/2018] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Naturally occurring hypothyroidism in adult cats is rare, with only 4 cases reported. OBJECTIVES To describe the historical, clinical, laboratory, and scintigraphic features of adult cats with spontaneous hypothyroidism. ANIMALS Seven adult cats referred for suspected hypothyroidism. METHODS Prospective case series. We collected data on cats' signalment, clinical signs, results of physical examination, routine laboratory and thyroid hormone testing, and thyroid imaging (thyroid scintigraphy or ultrasound). We subsequently treated cats with levothyroxine and evaluated their response to treatment. RESULTS Cats ranged from 3.5 to 11 years, with no apparent breed predilection; 6/7 cats were male. Only 2/7 cats were initially tested because of signs of hypothyroidism (hair-coat changes, lethargy, obesity); others were tested for routine thyroid monitoring or palpable thyroid nodules. Four were azotemic (serum creatinine, 2.2-3.4 mg/dL). Six of the cats had low serum thyroxine (T4 ) and free T4 (fT4 ) concentrations, whereas all 7 cats had high thyroid-stimulating hormone (TSH) concentrations. In 6/7 cats, thyroid scintigraphy revealed bilateral goiter with intense radionuclide uptake; imaging showed no visible thyroid tissue in the other. After levothyroxine treatment, serum concentrations of T4 and fT4 increased and TSH fell; high serum creatinine normalized in azotemic cats; and repeat imaging showed reduction in goiter size. CONCLUSIONS AND CLINICAL IMPORTANCE Primary hypothyroidism develops in adult cats, with a higher prevalence than previously thought. Most cats appear to develop a goitrous form of hypothyroidism associated with thyroid hyperplasia, whereas thyroid atrophy appears to be less common. With levothyroxine replacement, clinical and laboratory abnormalities improve or resolve.
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Affiliation(s)
- Mark E. Peterson
- Animal Endocrine ClinicNew York
- College of Veterinary MedicineCornell UniversityIthacaNew York
| | | | | | - Mark Rishniw
- College of Veterinary MedicineCornell UniversityIthacaNew York
- Veterinary Information NetworkDavisCalifornia
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Peterson ME, Rishniw M, Bilbrough GE, Cote KB. Comparison of in-clinic point-of-care and reference laboratory total thyroxine immunoassays for diagnosis and post-treatment monitoring of hyperthyroid cats. J Feline Med Surg 2018; 20:319-324. [PMID: 28494633 PMCID: PMC11129217 DOI: 10.1177/1098612x17708918] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2024]
Abstract
Objectives The Catalyst One Chemistry Analyzer (IDEXX Laboratories) is a point-of-care instrument that can measure total thyroxine (TT4) by immunoassay. The aims of this study were to evaluate the analytic performance of the Catalyst TT4 assay in feline sera and to examine agreement of the Catalyst TT4 results with those measured by immunoassay at a veterinary reference laboratory. Methods Assay precision, reproducibility and linearity were evaluated for the Catalyst TT4 assay. For method comparison, TT4 concentrations in serum samples from 157 cats (127 hyperthyroid, 30 radioiodine-treated cats) were analyzed by both in-clinic and reference laboratory methods. Results The Catalyst TT4 demonstrated good precision and reproducibility (coefficients of variation ⩽8.5%) and excellent linearity in the diagnostic range of 6-150 nmol/l. Differences between the two TT4 methods showed no proportional or fixed bias (Bland-Altman plots) but did demonstrate greater spread of values at higher TT4 concentrations. Statistical analysis of percent differences between methods indicated 95% limits of agreement of ± 30%. When serum TT4 concentrations were classified as low, high or within the reference interval (12-50 nmol/l) for each assay, there was strong agreement (96.8%) in classification between methods. Conclusions and relevance The Catalyst TT4 assay provided precise serum TT4 concentrations in the 157 samples analyzed, which agreed well with results provided by a reference laboratory. Cats with Catalyst TT4 concentrations near decision thresholds (eg, normal vs high) should either have TT4 concentration repeated a few weeks later and/or undergo further testing (eg, free T4, serum thyroid-stimulating hormone, thyroid scintigraphy) to determine thyroid status.
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Affiliation(s)
- Mark E Peterson
- Animal Endocrine Clinic, New York, NY, USA
- Cornell University, Ithaca, NY, USA
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Bree L, Gallagher BA, Shiel RE, Mooney CT. Prevalence and risk factors for hyperthyroidism in Irish cats from the greater Dublin area. Ir Vet J 2018; 71:2. [PMID: 29372047 PMCID: PMC5769238 DOI: 10.1186/s13620-017-0113-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2017] [Accepted: 12/21/2017] [Indexed: 11/10/2022] Open
Abstract
Background Hyperthyroidism is common in older cats. Prevalence varies geographically, but is anecdotally considered low in Ireland. The aim of this study was to document prevalence of hyperthyroidism in older cats in the greater Dublin area of Ireland and to assess environmental and clinical associations for development and identification of the disease. Methods Primary-care veterinary practices were requested to select cats aged 10 years or older where blood sampling was being performed for health screening or clinical investigations. Surplus serum/plasma samples were submitted to University College Dublin Diagnostic Endocrine Laboratory for total thyroxine (T4) measurement. Cats were classified as hyperthyroid, equivocal or euthyroid based on a total T4 concentration (reference interval, 15-60 nmol/L), of >60 nmol/L, 30-60 nmol/L or <30 nmol/L, respectively. Simultaneous free T4 or repeat (after 4-6 weeks) total T4 measurement was recommended in all equivocal cases. Animals receiving treatment for hyperthyroidism were excluded. A questionnaire completed by the client and veterinarian detailing historical and physical information was also required. Associations between categorical variables were analysed by Chi-square or Fisher's exact test and odds ratio (OR) calculated. A P value of <0.05 was considered statistically significant. Results Samples were submitted from 507 cats including 107 (21.1%) hyperthyroid, 54 (10.6%) equivocal and 346 (68.2%) euthyroid. The presence of goitre (P < 0.0001), tachypnoea (P = 0.0378), tachycardia (P = 0.002), polyphagia (P = 0.0003) and weight loss (P < 0.0001) were significantly associated with hyperthyroidism. Cats with goitre were more likely to be diagnosed as hyperthyroid [OR 2.85, (95% CI 1.75-4.62] compared to those without. However, goitre was only palpated in 40 of 102 (39.2%) hyperthyroid cats. Increasing age was the only significant (P < 0.002) risk factor for development of hyperthyroidism. A relationship between hyperthyroidism and sex, breed, lifestyle, parasite control, vaccination status or feeding habits was not identified. Conclusions Hyperthyroidism is not uncommon in Irish cats. Age was the only significant risk factor for its development. The high proportion of hyperthyroid cats without palpable goitre (> 60%) may reflect failure to detect goitre and account for the perceived low prevalence of this condition in Ireland.
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Affiliation(s)
- Laura Bree
- 1Section of Small Animal Clinical Studies, School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
| | - Barbara A Gallagher
- Present Address: Chestergates Veterinary Specialists, Telford Court Chestergates Roads Chester, Cheshire, CH1 6LT UK
| | - Robert E Shiel
- 1Section of Small Animal Clinical Studies, School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
| | - Carmel T Mooney
- 1Section of Small Animal Clinical Studies, School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
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Peterson M, Varela F, Rishniw M, Polzin D. Evaluation of Serum Symmetric Dimethylarginine Concentration as a Marker for Masked Chronic Kidney Disease in Cats With Hyperthyroidism. J Vet Intern Med 2018; 32:295-304. [PMID: 29377360 PMCID: PMC5787157 DOI: 10.1111/jvim.15036] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2017] [Revised: 09/28/2017] [Accepted: 11/30/2017] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Hyperthyroidism can complicate (mask) the diagnosis of chronic kidney disease (CKD) because it increases glomerular filtration rate and decreases body muscle mass, both of which can lower serum creatinine concentrations. Currently, there is no clinical test that can reliably predict which hyperthyroid cats have concurrent azotemic CKD that will become apparent after treatment of the hyperthyroidism. OBJECTIVES To investigate serum symmetric dimethylarginine (SDMA) concentration as a potential marker of masked azotemia in untreated hyperthyroid cats. ANIMALS Two hundred and sixty-two hyperthyroid cats and 206 aged-matched, clinically normal cats. METHODS Prospective study. We measured creatinine, urea nitrogen, SDMA, T4 , and TSH concentrations before and 1, 3, and 6 months after treatment with radioiodine (131 I) and classified 131 I-treated cats as azotemic or nonazotemic based on persistent, post-treatment creatinine concentrations >2.1 mg/dL. Groups were compared via nonparametric tests, and diagnostic accuracy was determined by receiver operating characteristic analysis and logistic regression. RESULTS No hyperthyroid cats were azotemic before treatment, but 42 (16%) became azotemic when rechecked at 4-8 months (median, 6 months) after 131 I treatment; of these, 14 had high SDMA concentrations before treatment. As a diagnostic test for pre-azotemic (masked) CKD in untreated hyperthyroid cats, SDMA showed a sensitivity of 33.3% and specificity of 97.7%. CONCLUSIONS AND CLINICAL IMPORTANCE Finding a high serum SDMA concentration in a hyperthyroid cat can help predict development of azotemia after treatment. The test has high diagnostic test specificity (few false-positive results) but relatively low sensitivity (fails to predict azotemia in most hyperthyroid cats).
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Affiliation(s)
- M.E. Peterson
- Animal Endocrine Clinic New YorkNY
- College of Veterinary Medicine Cornell UniversityIthacaNY
| | | | - M. Rishniw
- College of Veterinary Medicine Cornell UniversityIthacaNY
- Veterinary Information Network DavisCA
| | - D.J. Polzin
- University of Minnesota College of Veterinary Medicine St. PaulMN
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Volckaert V, Vandermeulen E, Stock E, Duchateau L, Daminet S, Hesta M, Saunders J, Dockx R, Peremans K. Week-to-week variation of scintigraphic (semi-)quantitative thyroid variables in 14 healthy experimental cats. Res Vet Sci 2017; 115:382-386. [DOI: 10.1016/j.rvsc.2017.07.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 07/06/2017] [Accepted: 07/08/2017] [Indexed: 11/16/2022]
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Peterson ME, Nichols R, Rishniw M. Serum thyroxine and thyroid-stimulating hormone concentration in hyperthyroid cats that develop azotaemia after radioiodine therapy. J Small Anim Pract 2017; 58:519-530. [DOI: 10.1111/jsap.12695] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 03/10/2017] [Accepted: 04/14/2017] [Indexed: 02/01/2023]
Affiliation(s)
- M. E. Peterson
- Animal Endocrine Clinic; New York NY 10025 USA
- Department of Clinical Sciences, College of Veterinary Medicine; Cornell University; Ithaca NY 14853 USA
| | - R. Nichols
- Animal Endocrine Clinic; New York NY 10025 USA
- Antech Diagnostics; Lake Success NY 11042 USA
| | - M. Rishniw
- Department of Clinical Sciences, College of Veterinary Medicine; Cornell University; Ithaca NY 14853 USA
- Veterinary Information Network; Davis CA 95615 USA
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25
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Kopecny L, Higgs P, Hibbert A, Malik R, Harvey AM. Management and monitoring of hyperthyroid cats: a survey of Australian veterinarians. J Feline Med Surg 2017; 19:559-567. [PMID: 26965675 PMCID: PMC11128808 DOI: 10.1177/1098612x16634392] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2024]
Abstract
Objectives This study sought to evaluate how Australian veterinarians approach management and monitoring of feline hyperthyroidism and compare these results with a similar survey recently performed in the UK. Methods An invitation to complete an online survey was sent to veterinarians in all states and territories of Australia. The survey comprised questions relating to management of hyperthyroidism, use of antithyroid drugs vs radioiodine treatment vs surgical thyroidectomy, in addition to demographic information for respondents. Results A total of 546 clinicians completed the survey. The most commonly preferred treatments for long-term management of feline hyperthyroidism were antithyroid medications (305/546; 56%) and radioiodine (210/546; 38%), with substantially more respondents selecting radioiodine when cost was removed as a consideration (425/546; 78%). However, most respondents had treated or referred few cases for radioiodine (median 2). Most veterinarians (500/546; 92%) used antithyroid medications either long term or prior to definitive treatment of hyperthyroidism. For medical management, 45% (244/546) of veterinarians used twice-daily carbimazole. Half of respondents (274/546) aimed to maintain the total thyroxine concentration anywhere within the laboratory reference interval in hyperthyroid cats without chronic kidney disease. Blood pressure monitoring was uncommon. Surgical thyroidectomy was rarely performed. Conclusions and relevance Radioiodine was more frequently preferred by Australian veterinarians compared with those in the UK, likely associated with greater availability, reduced cost and shorter hospitalisation times in this jurisdiction, although antithyroid medications were the most frequently used treatment modality. Barriers remain to its utilisation, however, including perceived cost, misconceptions with regard to expected success rate and accessibility. Recent changes to recommendations on the management and monitoring of hyperthyroid cats do not appear to have been widely adopted by veterinarians at this time.
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Affiliation(s)
- Lucy Kopecny
- Small Animal Specialist Hospital, Sydney, Australia
| | - Paul Higgs
- Eastcott Veterinary Referrals, Swindon, UK
| | - Angie Hibbert
- The Feline Centre, Langford Veterinary Services, University of Bristol, Bristol, UK
| | - Richard Malik
- Centre for Veterinary Education, The University of Sydney, Sydney, Australia
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26
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Lucy JM, Peterson ME, Randolph JF, Scrivani PV, Rishniw M, Davignon DL, Thompson MS, Scarlett JM. Efficacy of Low-dose (2 millicurie) versus Standard-dose (4 millicurie) Radioiodine Treatment for Cats with Mild-to-Moderate Hyperthyroidism. J Vet Intern Med 2017; 31:326-334. [PMID: 28158908 PMCID: PMC5354058 DOI: 10.1111/jvim.14646] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 09/18/2016] [Accepted: 11/29/2016] [Indexed: 12/02/2022] Open
Abstract
Background Radioiodine (131I) is effective treatment for hyperthyroidism in cats, but optimal dose to restore euthyroidism without inducing hypothyroidism is unclear. Treatment‐induced hypothyroidism can lead to azotemia and reduced duration of survival. Objective To compare efficacy and short‐term outcomes of low‐dose 131I versus higher, standard‐dose 131I as treatment for hyperthyroidism. Animals A total of 189 client‐owned cats undergoing 131I treatment for mild‐to‐moderate hyperthyroidism (serum T4 ≥ 4.0 μg/dL and <13.0 μg/dL). Methods Prospective, nonrandomized, cohort study comparing treatment with either low‐dose (2 mCi, n = 150) or standard‐dose (4 mCi, n = 39) 131I. Serum T4, thyroid‐stimulating hormone (TSH), and creatinine concentrations were measured after 1, 3, and 6 months to determine persistent hyperthyroidism, overt hypothyroidism (low T4, high TSH), subclinical hypothyroidism (normal T4, high TSH), and azotemia. Results There was no significant difference in prevalence of cats with persistent hyperthyroidism between standard‐ and low‐dose treatment groups at 3 (0% versus 5.3%; P = .34) and 6 (0% versus 3.3%; P = .51) months. Overt (18% versus 1%; P = .0005) or subclinical (46% versus 21%; P = .004) hypothyroidism was more common in cats at 6 months after standard‐dose 131I. No difference in incidence of azotemia existed between groups, but cats treated with standard‐dose 131I had higher creatinine concentrations (P < .05) and higher percent rises in creatinine (P < .0001). Conclusions and Clinical Importance Low‐dose 131I is safe and effective for cats with mild‐to‐moderate hyperthyroidism, as evidenced by a cure rate of >95% with reduced frequency of iatrogenic hypothyroidism and azotemia.
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Affiliation(s)
- J M Lucy
- Departments of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY
| | | | - J F Randolph
- Departments of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY
| | - P V Scrivani
- Departments of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY
| | - M Rishniw
- Departments of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY
| | - D L Davignon
- Departments of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY
| | - M S Thompson
- Departments of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY
| | - J M Scarlett
- Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY
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27
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28
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Peterson ME, Castellano CA, Rishniw M. Evaluation of Body Weight, Body Condition, and Muscle Condition in Cats with Hyperthyroidism. J Vet Intern Med 2016; 30:1780-1789. [PMID: 27667652 PMCID: PMC5115195 DOI: 10.1111/jvim.14591] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 07/16/2016] [Accepted: 08/31/2016] [Indexed: 01/29/2023] Open
Abstract
Background The contribution of fat loss versus muscle wasting to the loss of body weight seen in hyperthyroid cats is unknown. Objectives To investigate body weight, body condition score (BCS), and muscle condition score (MCS) in hyperthyroid cats. Animals Four hundred sixty‐two cats with untreated hyperthyroidism, 117 of which were reevaluated after treatment. Methods Prospective cross‐sectional and before–after studies. Untreated hyperthyroid cats had body composition evaluated (body weight, BCS, and MCS). A subset of these cats were reevaluated 3–12 months after treatment when euthyroid. Results Pretreatment body weight (median, 4.36 kg; IQR, 3.5 to 5.2 kg) was lower than premorbid weight (5.45 kg; IQR, 4.6 to 6.4 kg, P < .0001) recorded 1–2 years before diagnosis. 154 (35.3%) cats were thin or emaciated; 357 (77.3%) had loss of muscle mass. Cats showed increases in body weight (median, 4.1 kg to 5.0 kg), BCS (median, 3/5 to 3.5/5), and MCS (2/3 to 3/3) after treatment (P < .001), but mild‐to‐moderate muscle wasting persisted in 45% of treated cats. Conclusions and Clinical Importance Most hyperthyroid cats lose body weight but maintain an ideal or overweight BCS, with only a third being underweight. As in human hyperthyroid patients, this weight loss is associated with muscle wasting, which affects >75% of hyperthyroid cats. Successful treatment leads to weight gain and increase of BCS in most cats, but almost half fail to regain normal muscle mass.
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Affiliation(s)
- M E Peterson
- Animal Endocrine Clinic, New York, NY.,College of Veterinary Medicine, Cornell University, Ithaca, NY
| | | | - M Rishniw
- College of Veterinary Medicine, Cornell University, Ithaca, NY.,Veterinary Information Network, Davis, CA
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29
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Carney HC, Ward CR, Bailey SJ, Bruyette D, Dennis S, Ferguson D, Hinc A, Rucinsky AR. 2016 AAFP Guidelines for the Management of Feline Hyperthyroidism. J Feline Med Surg 2016; 18:400-16. [PMID: 27143042 PMCID: PMC11132203 DOI: 10.1177/1098612x16643252] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2024]
Abstract
CLINICAL CONTEXT Since 1979 and 1980 when the first reports of clinical feline hyperthyroidism (FHT) appeared in the literature, our understanding of the disease has evolved tremendously. Initially, FHT was a disease that only referral clinicians treated. Now it is a disease that primary clinicians routinely manage. Inclusion of the measurement of total thyroxine concentration in senior wellness panels, as well as in diagnostic work-ups for sick cats, now enables diagnosis of the condition long before the cat becomes the classic scrawny, unkempt, agitated patient with a bulge in its neck. However, earlier recognition of the problem has given rise to several related questions: how to recognize the health significance of the early presentations of the disease; how early to treat the disease; whether to treat FHT when comorbid conditions are present; and how to manage comorbid conditions such as chronic kidney disease and cardiac disease with treatment of FHT. The 2016 AAFP Guidelines for the Management of Feline Hyperthyroidism (hereafter referred to as the Guidelines) will shed light on these questions for the general practitioner and suggest when referral may benefit the cat. SCOPE The Guidelines explain FHT as a primary disease process with compounding factors, and provide a concise explanation of what we know to be true about the etiology and pathogenesis of the disease.The Guidelines also:Distill the current research literature into simple recommendations for testing sequences that will avoid misdiagnosis and separate an FHT diagnosis into six clinical categories with associated management strategies.Emphasize the importance of treating all hyperthyroid cats, regardless of comorbidities, and outline the currently available treatments for the disease.Explain how to monitor the treated cat to help avoid exacerbating comorbid diseases.Dispel some of the myths surrounding certain aspects of FHT and replace them with an evidence-based narrative that veterinarians and their practice teams can apply to feline patients and communicate to their owners. EVIDENCE BASE To help ensure better case outcomes, the Guidelines reflect currently available, evidenced-based knowledge. If research is lacking, or if a consensus does not exist, the expert panel of authors has made recommendations based on their extensive, cumulative clinical experience.
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Affiliation(s)
- Hazel C Carney
- WestVet Emergency and Specialty Center, 5019 North Sawyer Avenue, Garden City, ID 83617, USA
| | - Cynthia R Ward
- University of Georgia, College of Veterinary Medicine, 2200 College Station Road, Athens, GA 30605,USA
| | - Steven J Bailey
- Exclusively Cats Veterinary Hospital, 6650 Highland Road, Ste 116, Waterford, MI 48327, USA
| | - David Bruyette
- VCA West Los Angeles Animal Hospital, 1900 South Sepulveda Blvd, Los Angeles, CA 90025, USA
| | - Sonnya Dennis
- Stratham-Newfields Veterinary Hospital, 8 Main Street, Newfields, NH 03856, USA
| | - Duncan Ferguson
- College of Veterinary Medicine - University of Illinois, Department of Comparative Biosciences, 3840 Veterinary Medicine Basic Sciences Bldg, 2001 South Lincoln Avenue, Urbana, IL 61802, USA
| | - Amy Hinc
- Cosmic Cat Veterinary Clinic, 220 East Main Street, Branford, CT 06405, USA
| | - A Renee Rucinsky
- Mid Atlantic Cat Hospital, 201 Grange Hall Road, Queenstown, MD 21658, USA
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30
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Peterson ME, Guterl JN, Rishniw M, Broome MR. EVALUATION OF QUANTITATIVE THYROID SCINTIGRAPHY FOR DIAGNOSIS AND STAGING OF DISEASE SEVERITY IN CATS WITH HYPERTHYROIDISM: COMPARISON OF THE PERCENT THYROIDAL UPTAKE OF PERTECHNETATE TO THYROID-TO-SALIVARY RATIO AND THYROID-TO-BACKGROUND RATIOS. Vet Radiol Ultrasound 2016; 57:427-40. [DOI: 10.1111/vru.12360] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 11/09/2015] [Accepted: 11/09/2015] [Indexed: 01/18/2023] Open
Affiliation(s)
- Mark E. Peterson
- Animal Endocrine Clinic; New York NY 10025
- Cornell University College of Veterinary Medicine; Ithaca NY 14853
| | | | - Mark Rishniw
- Cornell University College of Veterinary Medicine; Ithaca NY 14853
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31
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Volckaert V, Vandermeulen E, Duchateau L, Saunders JH, Peremans K. Inter- and intraobserver variability of (semi-)quantitative parameters commonly used in feline thyroid scintigraphy. Res Vet Sci 2016; 105:87-91. [DOI: 10.1016/j.rvsc.2016.01.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Revised: 01/11/2016] [Accepted: 01/19/2016] [Indexed: 11/27/2022]
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32
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Peterson ME, Broome MR, Rishniw M. Prevalence and degree of thyroid pathology in hyperthyroid cats increases with disease duration: a cross-sectional analysis of 2096 cats referred for radioiodine therapy. J Feline Med Surg 2016; 18:92-103. [PMID: 25673019 PMCID: PMC11149013 DOI: 10.1177/1098612x15572416] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2024]
Abstract
OBJECTIVES Hyperthyroidism is common in cats, but there are no reports that evaluate its severity or underlying thyroid tumor disease based on disease duration (ie, time from original diagnosis). The objective of this study was to compare serum thyroxine (T4) concentrations and thyroid scintigraphic characteristics of cats referred for radioiodine treatment based on disease duration. METHODS This was a cross-sectional study of 2096 cats with hyperthyroidism. Cats were divided into five groups based on time from diagnosis: ⩽1 year (n = 1773); >1-2 years (n = 169); >2-3 years (n = 88); >3-4 years (n = 35); and >4-6.1 years (n = 31). Methimazole, administered to 996 (47.5%) cats, was stopped at least 1 week prior to examination to allow for serum T4 testing. Each thyroid scintiscan was evaluated for pattern (unilateral, bilateral, multifocal), location (cervical, thoracic inlet, chest) and size (small, medium, large, huge) of the thyroid tumor, as well as features suggesting malignancy. RESULTS Median serum T4 concentration increased with increasing disease duration from 100 nmol/l (⩽1 year) to 315 nmol/l (>4-6.1 years) (P <0.001). Prevalence of unilateral thyroid disease decreased, whereas multifocal disease (three or more tumor nodules) increased (P <0.001) with increasing disease duration. Median tumor volume in the five groups increased from 1.6 cm(3) (⩽1 year) to 6.4 cm(3) (>4-6.1 years). Prevalence of large (4-8 cm(3)) and huge (>8 cm(3)) thyroid tumors increased from 5.1% (⩽1 year) to 88.6% (>4-6.1 years), while the prevalence of intrathoracic tumor tissue increased from 3.4% (⩽1 year) to 32.3% (>4-6.1 years). Prevalence of suspected thyroid carcinoma (characterized by severe hyperthyroidism; huge, intrathoracic, multifocal tumors; refractory to methimazole treatment) increased with increasing disease duration from 0.4% (⩽1 year) to 19.3% (>4-6.1 years). CONCLUSIONS AND RELEVANCE Our results indicate that the prevalence of severe hyperthyroidism, large thyroid tumors, multifocal disease, intrathoracic thyroid masses and suspected malignant disease all increase with disease duration in cats referred for radioiodine therapy.
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Affiliation(s)
| | | | - Mark Rishniw
- College of Veterinary Medicine, Cornell University, Ithaca, NY, USA Veterinary Information Network, Davis, CA, USA
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33
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Bettencourt A, Daniel GB, Panciera D, Larson M, Werre SR. EVALUATION OF THYROID TO BACKGROUND RATIOS AND COMPARISON OF VARIOUS SCINTIGRAPHIC MEASUREMENTS AND THEIR CORRELATION TO SERUM T4IN HYPERTHYROID CATS. Vet Radiol Ultrasound 2016; 57:290-8. [DOI: 10.1111/vru.12343] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 10/20/2015] [Accepted: 11/02/2015] [Indexed: 11/28/2022] Open
Affiliation(s)
- Ann Bettencourt
- Department of Small Animal Clinical Sciences; Virginia-Maryland College of Veterinary Medicine, Virginia Tech; Blacksburg VA 24061
| | - Gregory B. Daniel
- Department of Small Animal Clinical Sciences; Virginia-Maryland College of Veterinary Medicine, Virginia Tech; Blacksburg VA 24061
| | - David Panciera
- Department of Small Animal Clinical Sciences; Virginia-Maryland College of Veterinary Medicine, Virginia Tech; Blacksburg VA 24061
| | - Marti Larson
- Department of Small Animal Clinical Sciences; Virginia-Maryland College of Veterinary Medicine, Virginia Tech; Blacksburg VA 24061
| | - Stephen R. Werre
- Laboratory for Study Design and Statistical Analysis; Virginia-Maryland College of Veterinary Medicine, Virginia Tech; Blacksburg VA 24061
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34
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Peterson ME. Primary goitrous hypothyroidism in a young adult domestic longhair cat: diagnosis and treatment monitoring. JFMS Open Rep 2015; 1:2055116915615153. [PMID: 28491394 PMCID: PMC5362015 DOI: 10.1177/2055116915615153] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/11/2015] [Indexed: 11/17/2022] Open
Abstract
Case summary Primary goitrous hypothyroidism was diagnosed in a 12-month-old cat examined because of small stature, mental dullness, severe lethargy, generalized weakness and gait abnormalities. Radiographs of the long bones and spine revealed delayed epiphyseal ossification and epiphyseal dysgenesis. Diagnosis of primary hypothyroidism was confirmed by low serum concentrations of total and free thyroxine (T4) with high thyroid-stimulating hormone (TSH) concentrations. Thyroid scintigraphy revealed severe enlargement of both thyroid lobes, as evidenced by a seven-fold increase in calculated thyroid volume above the reference interval. In addition, this bilateral goiter had an extremely high radionuclide uptake, about 10-fold higher than the normal feline thyroid gland. Treatment with twice-daily levothyroxine (L-T4), administered on an empty stomach, resulted in increased alertness, playfulness, strength and improvement in gait, as well as an increase in body length and weight. L-T4 replacement also led to normalization of serum thyroid hormone and TSH concentrations, and complete resolution of goiter. Relevance and novel information Spontaneous hypothyroidism is rarely reported in cats, with congenital hypothyroidism in kittens diagnosed most frequently. Despite the fact that this cat was a young adult, it likely had a form of congenital hypothyroidism caused by dyshormonogenesis (defect in thyroid hormone synthesis) that led to compensatory development of goiter. In hypothyroid cats, treatment with L-T4 is best given twice daily on an empty stomach to ensure adequate absorption. Normalization of serum TSH and shrinkage of goiter, as well as improvement in clinical signs, is the goal of treatment for cats with goitrous hypothyroidism.
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Affiliation(s)
- Mark E Peterson
- Animal Endocrine Clinic, New York, NY, USA.,College of Veterinary Medicine, Cornell University, Ithaca, NY, USA
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35
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van Hoek I, Hesta M, Biourge V. A critical review of food-associated factors proposed in the etiology of feline hyperthyroidism. J Feline Med Surg 2015; 17:837-47. [PMID: 25366172 PMCID: PMC11112195 DOI: 10.1177/1098612x14556558] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Since the first description of feline hyperthyroidism (HT) in 1979, several studies have been undertaken to define the etiology of the disease. Epidemiologic studies, after investigating non-food- and food-associated factors, suggest a multifactorial etiology. However, in the absence of prospective cohort studies that can confirm a cause-and-effect relationship between HT and associated risk factors, no causative factor for HT has been identified to date. Feline HT resembles toxic nodular goiter in humans, with autonomously functioning upregulated iodide uptake systems. Contribution of the diet to HT development remains controversial. The purpose of this paper is to review critically the reported food-associated risk factors for HT.
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Affiliation(s)
- Ingrid van Hoek
- Royal Canin Research & Development Center, Aimargues, France
| | - Myriam Hesta
- Department of Nutrition, Genetics and Ethology, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium
| | - Vincent Biourge
- Royal Canin Research & Development Center, Aimargues, France
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36
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Peterson ME, Guterl JN, Nichols R, Rishniw M. Evaluation of Serum Thyroid-Stimulating Hormone Concentration as a Diagnostic Test for Hyperthyroidism in Cats. J Vet Intern Med 2015; 29:1327-34. [PMID: 26192742 PMCID: PMC4858046 DOI: 10.1111/jvim.13585] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2015] [Revised: 06/18/2015] [Accepted: 06/23/2015] [Indexed: 11/26/2022] Open
Abstract
Background In humans, measurement of serum thyroid‐stimulating hormone (TSH) concentration is commonly used as a first‐line discriminatory test of thyroid function. Recent reports indicate that canine TSH (cTSH) assays can be used to measure feline TSH and results can help diagnose or exclude hyperthyroidism. Objectives To investigate the usefulness of cTSH measurements as a diagnostic test for cats with hyperthyroidism. Animals Nine hundred and seventeen cats with untreated hyperthyroidism, 32 euthyroid cats suspected of having hyperthyroidism, and 131 clinically normal cats. Methods Prospective study. Cats referred to the Animal Endocrine Clinic for suspected hyperthyroidism were evaluated with serum T4, T3, free T4 (fT4), and TSH concentrations. Thyroid scintigraphy was used as the gold standard to confirm or exclude hyperthyroidism. Results Median serum TSH concentration in the hyperthyroid cats (<0.03 ng/mL) was significantly (P < .001) lower than concentrations in clinically normal cats (0.05 ng/mL) or euthyroid cats with suspected thyroid disease (0.06 ng/mL). Only 18 (2.0%) hyperthyroid cats had measurable TSH concentrations (≥0.03 ng/mL), whereas 114 (69.9%) of the 163 euthyroid cats had detectable concentrations. Combining serum TSH with T4 or fT4 concentrations lowered the test sensitivity of TSH from 98.0 to 97.0%, but markedly increased overall test specificity (from 69.9 to 98.8%). Conclusions and Clinical Importance Serum TSH concentrations are suppressed in 98% of hyperthyroid cats, but concentrations are measurable in a few cats with mild‐to‐moderate hyperthyroidism. Measurement of serum TSH represents a highly sensitive but poorly specific test for diagnosis of hyperthyroidism and is best measured in combination with T4 and fT4.
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Affiliation(s)
- M E Peterson
- Animal Endocrine Clinic, New York, NY.,College of Veterinary Medicine, Cornell University, Ithaca, NY
| | | | - R Nichols
- Animal Endocrine Clinic, New York, NY
| | - M Rishniw
- College of Veterinary Medicine, Cornell University, Ithaca, NY.,Veterinary Information Network, Davis, CA
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