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Elwell-Cuddy T, Li M, KuKanich B, Lin Z. The construction and application of a population physiologically based pharmacokinetic model for methadone in Beagles and Greyhounds. J Vet Pharmacol Ther 2018; 41:670-683. [DOI: 10.1111/jvp.12676] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 03/30/2018] [Accepted: 05/18/2018] [Indexed: 01/18/2023]
Affiliation(s)
- Trevor Elwell-Cuddy
- Institute of Computational Comparative Medicine (ICCM); Department of Anatomy and Physiology; College of Veterinary Medicine; Kansas State University; Manhattan Kansas
| | - Miao Li
- Institute of Computational Comparative Medicine (ICCM); Department of Anatomy and Physiology; College of Veterinary Medicine; Kansas State University; Manhattan Kansas
| | - Butch KuKanich
- Institute of Computational Comparative Medicine (ICCM); Department of Anatomy and Physiology; College of Veterinary Medicine; Kansas State University; Manhattan Kansas
| | - Zhoumeng Lin
- Institute of Computational Comparative Medicine (ICCM); Department of Anatomy and Physiology; College of Veterinary Medicine; Kansas State University; Manhattan Kansas
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Scollan KF, Bulmer BJ, Sisson DD. Validation of a commercially available enzyme immunoassay for measurement of plasma antidiuretic hormone concentration in healthy dogs and assessment of plasma antidiuretic hormone concentration in dogs with congestive heart failure. Am J Vet Res 2014; 74:1206-11. [PMID: 23977893 DOI: 10.2460/ajvr.74.9.1206] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To validate the use of a human enzyme immunoassay (EIA) kit for measurement of plasma antidiuretic hormone (ADH) concentration in dogs and evaluate plasma ADH concentrations in dogs with congestive heart failure (CHF) attributable to acquired cardiac disease, compared with findings in healthy dogs. ANIMALS 6 healthy dogs and 12 dogs with CHF as a result of chronic degenerative valve disease or dilated cardiomyopathy. PROCEDURES Plasma samples from the 6 healthy dogs were pooled and used to validate the EIA kit for measurement of plasma ADH concentration in dogs by assessing intra-assay precision, dilutional linearity, and spiking recovery. Following validation, plasma ADH concentrations were measured in the 6 healthy dogs and in the 12 dogs with CHF for comparison. RESULTS The EIA kit measured ADH concentrations in canine plasma samples with acceptable intra-assay precision, dilutional linearity, and spiking recovery. The intra-assay coefficient of variation was 11%. By use of this assay, the median plasma concentration of ADH in dogs with CHF was 6.15 pg/mL (SD, 3.2 pg/mL; range, 4.18 to 15.47 pg/mL), which was significantly higher than the median concentration in healthy dogs (3.67 pg/mL [SD, 0.93 pg/mL; range, 3.49 to 5.45 pg/mL]). CONCLUSIONS AND CLINICAL RELEVANCE Plasma ADH concentrations in dogs can be measured with the tested EIA kit. Plasma ADH concentrations were higher in dogs with CHF induced by acquired cardiac disease than in healthy dogs. This observation provides a basis for future studies evaluating circulating ADH concentrations in dogs with developing heart failure.
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Affiliation(s)
- Katherine F Scollan
- Department of Clinical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA.
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Pereira D, Marques J, Borges P, Batista P, Oliveira C, Nunes N, Lopes P. Efeitos cardiorrespiratórios da metadona, pelas vias intramuscular e intravenosa, em cadelas submetidas à ovariossalpingo-histerectomia. ARQ BRAS MED VET ZOO 2013. [DOI: 10.1590/s0102-09352013000400005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A metadona é um opioide pouco utilizado na medicina veterinária, e há, ainda, questionamentos quanto ao seu uso. Desse modo, comparou-se o emprego da metadona, administrada pelas vias IM e IV, e avaliaram-se seus efeitos sobre as características cardiorrespiratórias e os tempos de extubação e recuperação em cadelas submetidas à ovariossalpingo-histerectomia. Utilizaram-se 16 cadelas, pré-medicadas com levomepromazina, 0.6mg/kg, IM. Após 20 minutos, a indução anestésica foi feita com propofol, 5mg/kg, IV, e a manutenção com isoflurano. Transcorridos 10 minutos, os animais receberam metadona, 0.3mg/kg, pelas vias IM - grupo GIM - e IV - grupo GIV. As mensurações das frequências cardíaca (FC) e respiratória (FR), pressão arterial média (PAM), temperatura esofágica (TE), pressão parcial de dióxido de carbono (EtCO2) e saturação de oxi-hemoglobina (SpO2) foram registradas antes da administração do opioide (T0), após 20 minutos (T1) e a cada 10 minutos da administração até 60 minutos (T2 a T5). Usou-se a análise de perfil (5%). Com relação à FC, PAM, FR, EtCO2, TE e SpO2, não foram observadas diferenças significativas entre grupos e momentos. Observaram-se tempos de extubação e recuperação maiores no GIV. É possível concluir que a administração IV e a IM da metadona não produzem alterações nas características cardiorrespiratórias em cadelas.
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Tünsmeyer J, Vaske B, Bösing B, Kästner SBR. Cardiovascular effects of a proprietary l-methadone/fenpipramide combination (Polamivet) alone and in addition to acepromazine in healthy Beagle dogs. Vet Anaesth Analg 2012; 39:451-63. [PMID: 22788416 DOI: 10.1111/j.1467-2995.2012.00757.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To determine the cardiovascular effects of a proprietary l-methadone/fenpipramide combination (Polamivet) alone and in addition to acepromazine in dogs. STUDY DESIGN Prospective, randomized, experimental crossover study. ANIMALS Five adult healthy Beagle dogs (one male and four females, weighing 12.8-16.4 kg). METHODS Dogs were instrumented for haemodynamic measurements whilst anaesthetized with isoflurane. Three hours after recovery dogs received 0.025 mg kg(-1) acepromazine (AP) or saline (SP) IM followed by 0.5 mg kg(-1) L-methadone/ 0.025 mg kg(-1) fenpipramide IV after 30 minutes. Cardiac output using thermodilution, heart rate, mean arterial pressure (MAP), central venous pressure (CVP), mean pulmonary artery pressure (MPAP), pulmonary artery occlusion pressure (PAOP), haemoglobin concentration, arterial and mixed-venous blood gas analysis were measured and sedation evaluated at baseline (BL), 30 minutes after acepromazine or saline IM (A/S), 5 minutes after L-methadone/fenpipramide IV application (35), every 15 minutes for 1 hour (50, 65, 80, 95 minutes) and every hour until baseline cardiac output was regained. Standard cardiovascular parameters were calculated. Data were analyzed by repeated measures anova and paired t-tests with p < 0.05 considered significant. RESULTS Baseline measurements did not differ. Cardiac index decreased after acepromazine administration in treatment AP (p = 0.027), but was not significantly influenced after l-methadone/fenpipramide injection in either treatment. In both treatments heart rate did not change significantly over time. Stroke volume index increased after A/S in both treatments (p = 0.049). Systemic vascular resistance index, MAP, CVP, MPAP, and pulmonary vascular resistance index did not change significantly after either treatment and did not differ between treatments. Dogs were deeply sedated in both treatments with a longer duration in treatment AP. CONCLUSIONS AND CLINICAL RELEVANCE In healthy dogs the dose of l-methadone/fenpipramide used in this study alone and in combination with acepromazine induced deep sedation without significant cardiovascular changes.
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Affiliation(s)
- Julia Tünsmeyer
- Small Animal Clinic, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany.
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MAIANTE AA, TEIXEIRA NETO FJ, BEIER SL, CORRENTE JE, PEDROSO CEBP. Comparison of the cardio-respiratory effects of methadone and morphine in conscious dogs. J Vet Pharmacol Ther 2009; 32:317-28. [DOI: 10.1111/j.1365-2885.2008.01042.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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van Vonderen IK, Wolfswinkel J, Oosterlaken-Dijksterhuis MA, Rijnberk A, Kooistra HS. Pulsatile secretion pattern of vasopressin under basal conditions, after water deprivation, and during osmotic stimulation in dogs. Domest Anim Endocrinol 2004; 27:1-12. [PMID: 15158530 DOI: 10.1016/j.domaniend.2004.01.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2003] [Accepted: 01/07/2004] [Indexed: 10/26/2022]
Abstract
Measurement of plasma osmolality (Posm) and plasma vasopressin (VP) concentration in response to hypertonicity is regarded as the gold standard for the assessment of VP release in polyuric conditions. Yet the interpretation of the VP curve as a function of Posm may be hampered by the occurrence of VP pulses. To determine whether VP is secreted in a pulsatile fashion in the dog and whether stimulation of VP release changes the secretion pattern of VP, we measured VP at 2-min intervals for 2 h under basal conditions, after 12 h of water deprivation, and during osmotic stimulation with hypertonic saline (20%) in eight healthy dogs. Vasopressin was secreted in a pulsatile fashion with a wide variation in number of VP pulses, VP pulse duration, and VP pulse amplitude and height. After water deprivation, total and basal VP secretion, the number of significant VP pulses, as well as the pulse characteristics did not differ from the basal situation. During osmotic stimulation, there was a large increase in both basal and pulsatile VP secretion, and the number of VP pulses and VP pulse height and amplitude were significantly increased. The VP pulse amplitude correlated significantly with the basal plasma VP concentration during osmotic stimulation. It is concluded that VP is secreted in a pulsatile manner in healthy dogs. The basal and pulsatile VP secretion increases during osmoreceptor-mediated stimulation. The VP pulses may occur to the magnitude that they may be interpreted as erratic bursts, when occurring in the hypertonic saline infusion test.
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Affiliation(s)
- I K van Vonderen
- Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, P.O. Box 80. 154, Yalelaan 8, 3508 TD Utrecht, The Netherlands
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Rijnberk A, Kooistra HS, van Vonderen IK, Mol JA, Voorhout G, van Sluijs FJ, IJzer J, van den Ingh TS, Boer P, Boer WH. Aldosteronoma in a dog with polyuria as the leading symptom. Domest Anim Endocrinol 2001; 20:227-40. [PMID: 11438403 DOI: 10.1016/s0739-7240(01)00090-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In a 10-year-old castrated male shorthaired German pointer polyuria was associated with slight hypokalemia, hypophosphatemia and alkalosis, as well as elevated plasma concentrations of a glucocorticoid-inducible iso-enzyme of alkaline phosphatase. Repeated measurements of urinary corticoids and normal suppressibility of the hypothalamus-pituitary-adrenocorticial axis excluded glucocorticoid excess. Urine osmolality (Uosm) did not increase during administration of the vasopressin analogue desmopressin. At the time water deprivation had caused Uosm to rise from 300 to 788 mOsm/kg, there was also plasma hypertonicity. During hypertonic saline infusion the osmotic threshold for vasopressin release was increased. The combination of elevated plasma aldosterone concentrations and unmeasurably low plasma renin activity pointed to primary hyperaldosteronism. As initially computed tomography (CT) did not reveal an adrenocortical lesion, the dog was treated with the aldosterone antagonist spironolactone. This caused Uosm to rise in a dose-dependent manner. However, well-concentrated urine was only achieved with doses that gave rise to adverse effects. Once repeated CT, using 2-mm-thick slices, had revealed a small nodule in the cranial pole of the left adrenal, unilateral adrenalectomy was performed which resolved the polyuria completely. Also the plasma concentrations of kalium, aldosterone and renin activity returned to within their respective reference ranges. The adrenocortical nodule had the histological characteristics of an aldosteronoma, with the non-affected zona glomerulosa being atrophic.In this dog with primary hyperaldosteronism the polyuria was characterized by vasopressin resistance and increased osmotic threshold of vasopressin release, similar to the polyuria of glucocorticoid excess. The possibility is discussed that the polyuria of glucocorticoid excess is actually a mineralocorticoid effect.
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Affiliation(s)
- A Rijnberk
- Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
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Vonderen IK, Kooistra HS, Sprang EP, Rijnberk A. Disturbed Vasopressin Release in 4 Dogs with So-Called Primary Polydipsia. J Vet Intern Med 1999. [DOI: 10.1111/j.1939-1676.1999.tb01457.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Meij BP, Mol JA, van den Ingh TS, Bevers MM, Hazewinkel HA, Rijnberk A. Assessment of pituitary function after transsphenoidal hypophysectomy in beagle dogs. Domest Anim Endocrinol 1997; 14:81-97. [PMID: 9063651 DOI: 10.1016/s0739-7240(96)00118-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Pituitary function was assessed in healthy adult beagle dogs before and after hypophysectomy. Anterior pituitary function was tested by use of the combined anterior pituitary (CAP) function test, which consisted of sequential 30-sec intravenous injections of four hypothalamic releasing hormones, in the following order and doses: 1 microgram of corticotropin-releasing hormone (CRH)/kg, 1 microgram of growth hormone-releasing hormone (GHRH)/kg, 10 micrograms of gonadotropin-releasing hormone (GnRH)/kg, and 10 micrograms of thyrotropin-releasing hormone (TRH)/kg. Plasma samples were assayed for adrenocorticotropin (ACTH), cortisol, GH, luteinizing hormone (LH), and prolactin (PRL) at multiple times for 120 min after injection. Pars intermedia function was assessed by the alpha-melanotropin (alpha-MSH) response to the intravenous injection of the dopamine antagonist haloperidol in a dosage of 0.2 mg/kg. Posterior pituitary function was assessed by the plasma vasopressin (AVP) response to the intravenous infusion of 20% saline. Basal plasma ACTH, cortisol, thyroxine, LH. PRL, and AVP concentrations were significantly lower at 10 wk after hypophysectomy than before hypophysectomy. In the CAP test and the haloperidol test, the peaks for the plasma concentrations of ACTH, cortisol, GH, LH, PRL, and alpha-MSH occurred within 45 min after injection. At 2 and 10 wk after hypophysectomy, there were no responses of plasma GH, LH, PRL, and alpha-MSH to stimulation. In four of eight hypophysectomized dogs, there were also no plasma ACTH and cortisol responses, whereas in the other four dogs, plasma ACTH and cortisol responses were significantly attenuated. The basal plasma ACTH and cortisol concentrations were significantly lower in the corticotropic nonresponders than in the responders. Plasma AVP responses were completely abolished by hypophysectomy, although water intake by the dogs was normal. Histopathological examinations at 10 wk after hypophysectomy revealed that adrenocortical atrophy was much more pronounced in the corticotropic nonresponders than in the responders. No residual pituitary tissue was found along the ventral hypothalamic diencephalon. However, in all hypophysectomized dogs that were investigated, islets of pituitary cells were found embedded in fibrous tissue in the sella turcica. A significant positive correlation was found between the number of ACTH-immunopositive cells and the ACTH increment in the CAP test at 10 wk after hypophysectomy. It is concluded that 1) stimulation of the anterior pituitary with multiple hypophysiotropic hormones, stimulation of the pars intermedia with a dopamine antagonist, and stimulation of the neurohypophysis with hypertonic saline do not cause side effects that would prohibit routine use, 2) in the routine stimulation of the anterior pituitary and the pars intermedia, blood sampling can be confined to the first 45 min, 3) the ACTH and cortisol responses to hypophysiotropic stimulation are the most sensitive indicators for residual pituitary function after hypophysectomy, 4) small islets of pituitary cells in the sella turcica, containing corticotropic cells, are the most likely source of the attenuated corticotropic response that may occur after hypophysectomy, and 5) residual AVP release from the hypothalamus after hypophysectomy is sufficient to prevent diabetes insipidus, despite the fact that the AVP response to hypertonic saline infusion is completely abolished.
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Affiliation(s)
- B P Meij
- Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, The Netherlands
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Goossens MM, Rijnberk A, Mol JA, Wolfswinkel J, Voorhout G. Central diabetes insipidus in a dog with a pro-opiomelanocortin-producing pituitary tumor not causing hyperadrenocorticism. Vet Med (Auckl) 1995; 9:361-5. [PMID: 8531185 DOI: 10.1111/j.1939-1676.1995.tb01099.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Central diabetes insipidus was diagnosed by vasopressin measurements during hypertonic stimulation in a 9-year-old male giant Schnauzer with polyuria and polydipsia. The impaired release of vasopressin was believed to be caused by a large pituitary tumor, which was visualized by computed tomography. Studies of the function of the anterior lobe and the pars intermedia of the pituitary gland were conducted, and high concentrations of ACTH and alpha-melanotrophic hormone (alpha-MSH) were found without concomitant hyperadrenocorticism. Studies of the molecular size of the immunoreactive ACTH in plasma by gel filtration revealed that most of the circulating immunoreactivity was not ACTH but its precursor pro-opiomelanocortin (POMC) and low-molecular-weight POMC-derived peptides. The pituitary tumor of this dog probably originated from melanotrophic cells of the pars intermedia. The sensitivity of the pituitary-adrenocortical system for the suppressive effect of dexamethasone was unaffected.
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Affiliation(s)
- M M Goossens
- Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, The Netherlands
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Rothuizen J, Biewenga WJ, Mol JA. Chronic glucocorticoid excess and impaired osmoregulation of vasopressin release in dogs with hepatic encephalopathy. Domest Anim Endocrinol 1995; 12:13-24. [PMID: 7621676 DOI: 10.1016/0739-7240(94)00005-l] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Chronic liver disease may be accompanied by disturbed sodium and water homeostasis. There is usually sodium retention and ascites. However, spontaneous natriuresis has also been reported in humans and experimental animals with liver cirrhosis. Chronic hypercortisolism, which may occur in dogs with advanced liver disease, is known to induce the inhibition of the osmostimulation of vasopressin (AVP) release. We have therefore investigated the osmoregulation of AVP release in 11 dogs with chronic hypercortisolism associated with advanced liver dysfunction and hepatic encepahlopathy and in 10 control dogs. Basal pituitary-adrenocortical activity was investigated by measuring the concentration in multiple plasma samples of adrenocorticotropin (ACTH), alpha-melanocyte-stimulating hormone (MSH), and cortisol and the cortisol:creatinine ratio in 24-hr urine. Urine specific gravity was also measured. The feedback regulation of the system was investigated by measuring these hormones in plasma after an intravenous (iv) injection of 0.01 mg/kg of dexamethasone. The osmoregulation of the release of AVP was investigated by the intravenous infusion of a 20% NaCl solution at a flow rate of 0.03 ml/kg for 2 hr and the measurement of AVP in plasma sampled at 20-min intervals. The AVP release was analyzed in terms of the threshold osmolality at which it commenced and the sensitivity, which reflects the magnitude of the response. All dogs had highly increased urinary cortisol:creatinine ratios, ranging from 21 to 210 x 10(-6) (normally < 10 x 10(-6)). The mean basal plasma concentrations of the three pituitary-adrenocortical hormones were significantly increased. ACTH values were 35 to 146 ng/l (normally, 14 to 68), MSH values were 26 to 118 ng/l (normally, 10 to 36), and cortisol values were 88 to 194 nmol/l (normally, 23 to 112). The feedback inhibition of the secretion of ACTH and cortisol in response to dexamethasone was unaffected. Urine specific gravity was significantly decreased. The regulation of AVP release was found to be abnormal in all dogs with hepatic encephalopathy. The osmotic threshold at which the release of AVP was induced was abnormally high in seven of the dogs with liver disease and in the normal range in one. It could not be determined in three dogs. The sensitivity of AVP release in response to increasing plasma hypertonicity was normal in two dogs and decreased in nine. In three dogs, there was no increase in AVP release. None of the dogs had normal values for both the sensitivity and the threshold.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- J Rothuizen
- Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, University of Utrecht, The Netherlands
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Biewenga WJ, Rijnberk A, Mol JA. Persistent polyuria in two dogs following adrenocorticolysis for pituitary-dependent hyperadrenocorticism. Vet Q 1989; 11:193-7. [PMID: 2557704 DOI: 10.1080/01652176.1989.9694223] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
In two dogs with pituitary-dependent hyperadrenocorticism, adrenocorticolysis with o.p'-DDD led to the disappearance of the signs and symptoms except for the polyuria. After a modified water-deprivation test the osmoregulation of vasopressin release was studied by hypertonic saline infusion. In both dogs the hypertonicity, thus induced, resulted in very minimal responses of the vasopressin secretion.
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Affiliation(s)
- W J Biewenga
- Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, University of Utrecht, The Netherlands
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Hellebrekers LJ, Biewenga WJ, Mol JA. Effect of arginine vasopressin on urine formation and plasma atrial natriuretic peptide level in conscious dogs. Eur J Pharmacol 1989; 164:55-62. [PMID: 2526745 DOI: 10.1016/0014-2999(89)90230-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We investigated the relationship between plasma arginine vasopressin (AVP) and atrial natriuretic peptide (ANP) levels and urine formation in conscious dogs. The rate of urine production and urinary electrolyte excretion were determined following infusion of high doses of AVP to dogs in different volume states. Water deprivation for 24 h induced an antidiuresis while the plasma osmolality, plasma AVP and plasma ANP remained at physiological levels. Subsequent i.v. administration of AVP did not alter the production of urine. Oral water loading (20 ml/kg body weight) induced low plasma AVP levels (1.3 +/- 0.5 pg/ml, mean +/- S.E.M.). Following AVP administration to the water-loaded group, the urine production rate decreased significantly from baseline while the osmolality of the urine increased significantly. Plasma ANP levels did not differ significantly between the two experimental groups, and did not change following i.v. administration of AVP. The results show that, in conscious dogs, (1) the production of a small volume of highly concentrated urine can occur with plasma AVP levels of below 5 pg/ml, (2) 24 h of dehydration induces an antidiuresis while plasma peptides, as well as the different biochemical variables, remain within normal limits, (3) increased plasma AVP levels do not induce a change in plasma ANP levels under these experimental conditions, (4) infusion of AVP induces a significantly increased K+ excretion but only in overhydrated animals.
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Affiliation(s)
- L J Hellebrekers
- Subdepartment of Veterinary Anesthesia, Faculty of Veterinary Medicine, University of Utrecht, The Netherlands
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