Iatrogenic Hyperadrenocorticism in 12 Cats

2022 Update of the Consensus on the Rational Use of Antithrombotics and Thrombolytics in Veterinary Critical Care (CURATIVE) Domain 1- Defining populations at risk

OBJECTIVES

To expand the number of conditions and interventions explored for their associations with thrombosis in the veterinary literature and to provide the basis for prescribing recommendations.

DESIGN

A population exposure comparison outcome format was used to represent patient, exposure, comparison, and outcome. Population Exposure Comparison Outcome questions were distributed to worksheet authors who performed comprehensive searches, summarized the evidence, and created guideline recommendations that were reviewed by domain chairs. The revised guidelines then underwent the Delphi survey process to reach consensus on the final guidelines. Diseases evaluated in this iteration included heartworm disease (dogs and cats), immune-mediated hemolytic anemia (cats), protein-losing nephropathy (cats), protein-losing enteropathy (dogs and cats), sepsis (cats), hyperadrenocorticism (cats), liver disease (dogs), congenital portosystemic shunts (dogs and cats) and the following interventions: IV catheters (dogs and cats), arterial catheters (dogs and cats), vascular access ports (dogs and cats), extracorporeal circuits (dogs and cats) and transvenous pacemakers (dogs and cats).

RESULTS

Of the diseases evaluated in this iteration, a high risk for thrombosis was defined as heartworm disease or protein-losing enteropathy. Low risk for thrombosis was defined as dogs with liver disease, cats with immune-mediated hemolytic anemia, protein-losing nephropathy, sepsis, or hyperadrenocorticism.

CONCLUSIONS

Associations with thrombosis are outlined for various conditions and interventions and provide the basis for management recommendations. Numerous knowledge gaps were identified that represent opportunities for future studies.

Is methylprednisolone acetate-related insulin resistance preventable in cats?

Methylprednisolone acetate (MPA) is often prescribed to cats despite being recognized eventually as diabetogenic. To assess MPA-related insulin resistance and evaluate the efficacy of metformin or an obesity and diabetes mellitus (O&D) adjuvant diet as protective factors, a randomized clinical trial was conducted with 28 owned cats undergoing glucocorticoid therapy. A single MPA dose of 20 mg intramuscularly was administered to each cat. Controls (n=10) received only MPA. In the diet group (n=9), replacement of their habitual diet by ad-libitum feeding of a feline commercial O&D diet (Equilíbrio O&D, Total Alimentos ADM) was made. In the metformin group (n=9), metformin chlorhydrate 25mg/cat PO/q24h was administered for 30 days. All patients were clinically evaluated at baseline (T0), day 15 (T15), and day 30 (T30) and blood draw for complete blood count, serum biochemistry, and determination of insulin concentrations. Fasting Insulin Sensitivity Index (SI), Amended Insulin to Glucose Ratio (AIGR), Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), and Homeostatic Model Assessment of beta-cell function (HOMA-B) were calculated based on fasting glycemia and insulinemia. All groups showed significantly higher levels (p < 0.05) of neutrophils, albumin, glucose, cholesterol, triglycerides, and serum insulin at T15. Patients in the metformin group showed also higher SI, AIGR, and HOMA-IR results at T15. Also, at T15, reduced levels (p < 0.05) of eosinophils, lymphocytes, and creatinine were documented in all groups. An MPA single dose induced changes in insulin sensitivity in cats; however, neither metformin nor O&D feeding used in this study was effective as protective factors against MPA-related insulin resistance.

Oral dexamethasone sodium phosphate solution significantly reduces pruritus and clinical lesions in feline hypersensitivity dermatitis: an open-label study

BACKGROUND

There are no liquid oral glucocorticoids labelled for management of pruritus and clinical lesions of feline hypersensitivity dermatitis (feline HD).

HYPOTHESIS

First, to demonstrate that dexamethasone sodium phosphate (DexSP, DexajectSP, Henry Schein; Dublin, OH, USA; 4 mg/mL), an intravenous glucocorticoid, can be absorbed by healthy cats when administered orally. Second, to demonstrate the efficacy of orally administered DexSP for reducing pruritus and clinical lesions in patients with feline HD.

ANIMALS

Seven healthy and 12 client-owned cats with HD.

METHODS AND MATERIALS

Healthy cats were administered a single dose of 0.2 mg/kg DexSP p.o. and serum concentrations were measured using enzyme-linked immunosorbent assay (ELISA). Feline HD patients were assessed with SCORing Feline Allergic Dermatitis (SCORFAD) and pruritus Visual Analog Scale (pVAS) at Visit 1 (V1) and after 20-31 days of receiving 0.2 mg/kg/day DexSP p.o. (V2). Complete blood cell counts, serum chemistry profile, and urinalysis were performed in 50% of feline HD patients at both visits.

RESULTS

Healthy cats had detectable serum concentrations of DexSP following oral administration; concentrations ranged from 0.7 to 92.3 ng/mL. Feline HD patients showed significant decreases in SCORFAD and pVAS scores from V1 to V2.

CONCLUSIONS

DexSP was absorbed when administered orally to healthy cats and 0.2 mg/kg/day DexSP is an efficacious dose to rapidly improve the pruritus and clinical lesions associated with feline HD.

Case Report: Clinical Remission in a Cat With Severe Bilateral Eosinophilic Keratitis Receiving Combined Immunosuppressive Therapy (Triamcinolone Acetonide and Tacrolimus)

A 2-year-old domestic shorthair cat was examined for severe keratitis of 10 months duration, non-responsive to 0.1% dexamethasone q8-12h. Patient and owner compliance were poor given ocular discomfort and hiding behavior. On presentation, both eyes (OU) had severe ulcerative keratitis that masked examination of deeper structures and resulted in absent menace response OU. Corneal cytology was consistent with eosinophilic keratitis (EK) OU. Initial therapy included subcutaneous triamcinolone acetonide injection (0.2 mg/kg), 0.3% ciprofloxacin OU q12h, and two compounded drugs started 5 days later upon receipt: 0.5% tacrolimus OU q6h, 0.5% cidofovir OU q12h. Visual behavior and ocular comfort were reportedly much improved within 24 h. At the first recheck (Day 11), patient and owner compliance were reported to be excellent, menace response was positive OU, and keratitis was dramatically reduced OU with absent fluorescein uptake. Subcutaneous triamcinolone acetonide was repeated (0.2 mg/kg), ciprofloxacin was discontinued, cidofovir was continued q12h, and tacrolimus was slowly tapered (q8h × 3 weeks then q12h). Keratitis was nearly 100% resolved at the second recheck (Day 38); cidofovir was discontinued and tacrolimus was slowly tapered (q12h × 1 week, q24h × 4 weeks, q48h × 4 weeks) then discontinued. A third recheck (Day 101) confirmed clinical remission OU, and disease did not reoccur within a 1 year follow up period (photographic documentation by owner). In sum, adjunct use of triamcinolone acetonide greatly improved therapeutic compliance and helped control severe EK in a rapid and effective manner.

Feline comorbidities: Recognition, diagnosis and management of the cushingoid diabetic

PRACTICAL RELEVANCE

Diabetes mellitus (DM) is a common feline endocrinopathy, and is often driven by underlying insulin resistance with associated pancreatic beta (β)-cell dysfunction. Although spontaneous hyperadrenocorticism (HAC) with hypercortisolemia (hypercortisolism) is relatively uncommon in cats, it is a well-established cause of insulin resistance and is routinely associated with DM in this species.

CLINICAL CHALLENGES

Many of the clinical signs associated with feline HAC are subtle and may be attributed to concurrent DM or the aging process. Failure to recognize HAC in the diabetic cat can impact patient wellbeing and predispose the patient to progressive compromise. Unfortunately, it can be difficult to establish a diagnosis of HAC, as test results may be influenced by poor diabetic regulation, and protocols are different to those used in canine patients. Treatment options depend on the underlying cause, and often require careful, ongoing assessment and modulation of both adrenal function and insulin requirements. However, various approaches have been shown to either improve glycemic control in cats with sustained insulin dependence, or facilitate diabetic remission.

EVIDENCE BASE

This review summarizes the current literature on feline HAC, with a particular focus on cats with concurrent DM. The clinical findings that suggest HAC are discussed, along with an outline of diagnostic options and their limitations. Published outcomes for various medical options, surgical procedures and radiation therapy are provided. The authors also share their thoughts on the safe and effective management of cats with HAC and DM, with an emphasis on the anticipation and recognition of changing insulin requirements.

Serum thyroxine and thyrotropin concentrations decrease with severity of nonthyroidal illness in cats and predict 30-day survival outcome

Background

In cats, nonthyroidal illness affects serum thyroid hormone concentrations. Serum thyroxine (T₄) and triiodothyronine (T₃) concentrations commonly decrease, whereas free T₄ (fT₄) concentrations vary unpredictably. Limited information exists regarding effects on serum thyrotropin (thyroid‐stimulating hormone [TSH]) concentrations in cats with nonthyroidal illness syndrome (NTIS).

Objectives

To characterize alterations in thyroid function that develop in cats with NTIS and to correlate these alterations with severity and outcome of the nonthyroidal illness.

Animals

Two hundred and twenty‐two cats with NTIS and 380 clinically normal cats of similar age and sex.

Methods

Prospective, cross‐sectional study. All cats had serum T₄, T₃, free T₄, and TSH concentrations measured. Cats were grouped based on illness severity and 30‐day survival.

Results

Cats with NTIS had lower serum T₄ and T₃ concentrations than did normal cats (P < .001). Serum fT₄ and TSH concentrations did not differ between groups. Serum T₄, T₃, and fT₄ concentrations progressively decreased with increasing disease severity (P < .001). The 56 cats that died had lower T₄, T₃, and TSH concentrations than did the 166 survivors, with no difference in fT₄ concentration. Multivariable logistic regression modeling indicated that serum T₄ and TSH concentrations both predicted survival (P < .02).

Conclusions and Clinical Importance

Cats with NTIS commonly develop low serum T₄, T₃, and TSH concentrations, the prevalence and extent of which increases with disease severity. Clinicians should consider evaluating thyroid function in cats with severe NTIS, because doing so could help determine probability of successful treatment responses before investing considerable time, effort, and finances in addressing the underlying disease.

Peculiarities of feline hyperadrenocorticism: Update on diagnosis and treatment

Practical relevance: Hyperadrenocorticism (HAC) is a relatively uncommon endocrinopathy of older cats, with a mean age at diagnosis of 10 years. In addition to pituitary-dependent and adrenal-dependent hypercortisolism, clinical signs of HAC can result from adrenal sex steroid-producing tumours. Clinical challenges: While HAC in cats has many similarities to canine HAC, there are key differences in presentation, diagnosis and response to therapy. Most, but not all, cats with HAC have concurrent diabetes mellitus, which is often insulin resistant. Up to a third of cats with HAC have extreme skin fragility and are at high risk of debilitating iatrogenic skin tears during diagnostic or therapeutic interventions. Infections of the skin and nail beds, and urinary, respiratory and gastrointestinal tract, secondary to cortisol-induced immune suppression, are also common. Cats respond differently to dogs to adrenal function tests including adrenocorticotropic hormone (ACTH) stimulation and dexamethasone suppression tests; a 10-fold higher dose of dexamethasone is recommended in cats to screen for HAC. Curative treatment options include adrenalectomy or transsphenoidal hypophysectomy. Radiation or medical treatment may improve clinical signs. The response to mitotane therapy is poor. While trilostane is the medical treatment of choice based on retrospective studies, investigations into the pharmacokinetics of this drug in cats are lacking. Global importance: Feline HAC occurs worldwide and is not associated with any purebreed predisposition. Although uncommon, adrenal sex steroid-producing tumours have a higher prevalence in cats than in dogs. Evidence base: The information in this review is drawn from over 180 reported cases of feline HAC. Reports investigating clinical presentation, clinicopathological findings and treatment outcomes are observational, retrospective multiple case series (EBM grade III) or single case reports (EBM grade IV). While most endocrine testing studies for diagnosis are cohort controlled analytical studies (EBM grade III), prospective, randomised, placebo-controlled studies have been performed (EBM grade I).

Epidemiology of Diabetes Mellitus among 193,435 Cats Attending Primary-Care Veterinary Practices in England

BACKGROUND

Diabetes mellitus (DM) is a common endocrine disease of cats. The prevalence of DM in cats in England is not well-defined.

HYPOTHESIS/OBJECTIVES

To estimate the prevalence and identify risk factors for DM in a large population of cats attending primary-care practices.

ANIMALS

A cohort of 193,563 cats in the VetCompass Programme attending 118 primary-care practices in England.

METHODS

Cross-sectional analysis of cohort clinical data. Data were extracted covering September 1st 2009 and August 31st 2014. Period prevalence of DM was calculated. Associations between risk factors and DM were assessed using logistic regression modelling.

RESULTS

Of 1,128 DM cases were identified among 194,563 cats (period prevalence 0.58%; 95% confidence interval [CI] 0.54-0.61). Multivariable modelling indicated that Tonkinese (OR 4.1; 95% CI 1.8-9.6; P = .001), Norwegian Forest (odds ratio [OR] 3.5; 95% CI 1.3-9.6; P = .001) and Burmese (OR 3.0; 95% CI 2.0-4.4; P < .001) cats had increased odds of DM compared with crossbred cats. DM odds increased as bodyweight categories increased above 4 kg (P < .001), as cats aged beyond 6 years old (P < .001) and in insured cats (OR 2.0; 95% CI 1.6-2.4; P < .001) but sex was not significantly associated with DM.

CONCLUSIONS AND CLINICAL IMPORTANCE

Diabetes mellitus is an important component of the primary-care practice caseload with 1-in-200 cats affected. An increased risk of DM in certain cat breeds supports a genetic predisposition. These results can guide future research and preventative healthcare.

Skin fragility syndrome in a cat with multicentric follicular lymphoma

An 11-year-old, spayed female domestic shorthair cat was presented for a right flank wound. On clinical examination, a single non-painful skin tear lesion with irregular edges was detected. During the examination, star-shaped cigarette paper-like skin lesions appeared spontaneously. An abdominal mass was also palpated. Feline skin fragility syndrome (FSFS) was suspected and a multicentric lymphoma was diagnosed by fine needle aspiration. The cat’s condition declined and it died spontaneously. Post-mortem examination confirmed the diagnosis of lymphoma. Neoplastic lymphocytes were not observed in the skin. Histological analysis of the skin was consistent with the morphological aspects of FSFS. A possible direct link between the two conditions remains a matter of speculation, but this case report provides the first description of FSFS associated with multicentric follicular lymphoma. Thus, multicentric follicular lymphoma should be considered as a differential diagnosis in cats presenting with FSFS.

Factors associated with clinical remission in cats with diabetes mellitus

Type 2 diabetes mellitus is a common endocrine disease in cats. The aim of this study was to investigate factors that are associated with clinical remission in diabetic cats, and those that might influence survival time. Medical records of 29 cats with diabetes mellitus were evaluated retrospectively. Data collected from each record included breed, age, and sex, types of diet before and after admission, degree of weight loss, duration of clinical signs before admission, elevation of alanine aminotransferase activity and ketonuria at the time of admission, concurrent pancreatitis or renal failure, glipizide administration, insulin supplement, and survival time. The diet after establishing diagnosis (restriction to non-carbohydrate canned food) was the only factor that was significantly associated with achieving clinical remission (P < 0.001). Survival time of cats was positively associated (P = 0.004) with clinical remission status and the type of diet after admission (P = 0.04) and negatively associated with the presence of chronic renal failure (P = 0.04). This was the first report of feline diabetes mellitus from Taiwan.

Expression of the Bcl-2 apoptotic marker in cats diagnosed with inflammatory bowel disease and gastrointestinal lymphoma

Immunolabeling for the critical lymphocyte survival factor, Bcl-2, of intestinal biopsies from cats with histologic evidence of inflammatory bowel disease (IBD) or gastrointestinal (GI) lymphoma was evaluated to determine if expression differed significantly between these two disease processes. Immunolabeling for Bcl-2 was performed on small intestinal endoscopic or full thickness biopsy sections from 55 cats. Diagnosis of IBD, T-cell lymphoma or B-cell lymphoma was established previously. The percentage of infiltrating lymphocytes that were positively labeled for Bcl-2 was subjectively determined for each case. Eight cats were diagnosed with IBD and 47 cats with lymphoma. A significantly higher percentage of cells were positively immunolabeled for Bcl-2 in cats with GI lymphoma [median (range); 90 (5-95)%] compared with cats with IBD [60 (15-95)%] (P = 0.029). However, the overall degree of positive immunolabeling in both groups tended to be high. This over-expression of Bcl-2 may prove useful as a therapeutic target for IBD and GI lymphoma in cats.

Disseminated Histoplasmosis Accompanied by Cutaneous Fragility in a Cat

A 4 yr old, spayed female domestic shorthair was referred with a 2 mo history of weight loss, anorexia, and diarrhea. Skin fragility was noted on presentation and a large skin tear measuring 5 cm × 5 cm was obvious over the dorsal cervical region. The patient was previously treated with short-term prednisone that was discontinued 6 wk before presentation. Initial diagnostics (complete blood count and biochemistry) did not indicate an endocrine disorder, the most common cause of acquired feline skin fragility. Necropsy revealed diffuse histoplasmosis (most significantly affecting the skin), epidermal atrophy, dermal collagen separation, and infiltration in the dermis and subcutis by inflammatory cells containing yeast organisms consistent with Histoplasma spp. Infiltrative fungal infection should be considered as a potential cause of acquired feline skin fragility.

Hyperglycaemia but not hyperlipidaemia causes beta cell dysfunction and beta cell loss in the domestic cat

AIMS/HYPOTHESIS

In vitro studies point to a toxic effect of high glucose and non-esterified fatty acids on beta cells. Whether elevated levels of glucose and lipids induce beta cell loss in vivo is less clear. The domestic cat has recently been proposed as a valuable animal model for human type 2 diabetes because feline diabetes shows several similarities with diabetes in humans, including obesity-induced insulin resistance, impaired beta cell function, decreased number of beta cells and pancreatic amyloid deposition.

METHODS

We infused healthy cats with glucose or lipids for 10 days to clamp their blood concentrations at the approximate level found in untreated feline diabetes (glucose: 25-30 mmol/l; triacylglycerols: 3-7 mmol/l).

RESULTS

Glucose and lipid levels were adequately targeted. Plasma non-esterified fatty acids were increased by lipid infusion 1.7-fold. A dramatic and progressive decline of plasma insulin levels was observed in glucose-infused cats beginning after 2 days of hyperglycaemic clamp. In contrast, plasma insulin concentration and glucose tolerance test were not affected by hyperlipidaemia. Compared with controls, glucose-infused cats had a 50% decrease in beta cells per pancreatic area. Apoptotic islet cells and cleaved caspase-3-positive beta cells were observed in glucose-infused cats only.

CONCLUSIONS/INTERPRETATION

Sustained hyperglycaemia but not hyperlipidaemia induces early and severe beta cell dysfunction in cats, and excess glucose causes beta cell loss via apoptosis in vivo. Hyperglycaemic clamps in cats may provide a good model to study the pathogenesis of glucose toxicity in beta cells.

Presumed primary immune-mediated thrombocytopenia in four cats

Feline primary immune-mediated thrombocytopenia (pIMT) is a rare hematological disorder. Platelet-bound antibody assays for cats have variable specificity and sensitivity and are not widely available. Diagnosis of pIMT is made on the basis of exclusion of other identifiable causes of thrombocytopenia and the response to immunosuppressive therapy. This report describes four cats with severe thrombocytopenia and no detectable underlying disease. One cat was euthanased because of pulmonary hemorrhage, while the other cats had frequent relapses, two of these cats developed diabetes mellitus due to long-term corticosteroid therapy. In these cats IMT had a chronic course and responded poorly to therapy with prednisolone. Alternative immunomodulatory drugs may be considered in the treatment of feline IMT.