Linear-Accelerator-Based Modified Radiosurgical Treatment of Pituitary Tumors in Cats: 11 Cases (1997–2008)

Objective: Determine the efficacy and safety of a linear-accelerator-based single fraction radiosurgical approach to the treatment of pituitary tumors in cats.
Design: Retrospective study.
Animals: Eleven client-owned cats referred for treatment of pituitary tumors causing neurological signs, or poorly controlled diabetes mellitus (DM) secondary either to acromegaly or pituitary-dependent hyperadrenocortism.
Procedures: Cats underwent magnetic resonance imaging (MRI) of the brain to manually plan radiation therapy. After MRI, modified radiosurgery was performed by delivering a single large dose (15 or 20 Gy) of radiation while arcing a linear-accelerator-generated radiation beam around the cat's head with the pituitary mass at the center of the beam. Eight cats were treated once, 2 cats were treated twice, and 1 cat received 3 treatments. Treated cats were evaluated for improvement in endocrine function or resolution of neurological disease by review of medical records or contact with referring veterinarians and owners.
Results: Improvement in clinical signs occurred in 7/11 (63.6%) of treated cats. Five of 9 cats with poorly regulated DM had improved insulin responses, and 2/2 cats with neurological signs had clinical improvement. There were no confirmed acute or late adverse radiation effects. The overall median survival was 25 months (range, 1–60), and 3 cats were still alive.
Conclusions and Clinical Importance: Single fraction modified radiosurgery is a safe and effective approach to the treatment of pituitary tumors in cats.     

Adverse Neurologic Events Associated with Voriconazole Use in 3 Cats

Background: Voriconazole has a broader spectrum of activity in comparison to fluconazole, itraconazole, and amphotericin B. Little documentation regarding appropriate dosing, efficacy, or adverse effects exists for cats. Neurologic adverse effects have been reported as a result of administration in other species. Hypothesis: Voriconazole administration resulted in neurologic abnormalities in 3 cats. Animals: Three cats that received voriconazole. Methods: Observational study of adverse effects associated with voriconazole administration. Results: All 3 cats had ataxia, which in 2 cats progressed to paraplegia of the rear limbs. Two of the cats had visual abnormalities including mydriasis, decreased to absent pupillary light responses, and decreased menace response. Arrhythmia and hypokalemia were noted in 2 separate cats. Conclusions and Clinical Importance: Voriconazole has potential neurologic adverse effects in cats. Additional information regarding pharmacokinetics of the drug in this species must be gathered to help determine how it can be dosed most effectively with minimal adverse effects.     

Antithrombotic Effect of Enoxaparin in Clinically Healthy Cats: A Venous Stasis Model

Background: Systemic arterial thromboembolic events are a serious complication of cardiac disease in cats.
Objectives: To determine if enoxaparin induces an antithrombotic effect in cats at a dosage of 1 mg/kg SC q12h and if this antithrombotic effect is predicted by anti-Xa activity.
Animals: Fourteen clinically healthy cats were divided into 3 groups: control (4 cats), treated and assessed at 4 hours (5 cats), and treated and assessed at 12 hours (5 cats).
Methods: A venous stasis model was used and the extent of thrombus formation estimated by measuring thrombus weight and accretion of ¹²⁵I-fibrinogen. Plasma anti-Xa activity was measured in treated cats.
Results: There was a significant reduction in thrombus formation in the 4 h group compared with control (median weight, 0.000 versus 0.565 mg/mm, P < .01; median %¹²⁵I-fibrinogen accretion, 0.0 versus 42.0%, P < .01). There was a reduction in thrombus formation in the 12 h group (median weight, 0.006 mg/mm, P = .09; median %¹²⁵I-fibrinogen accretion, 3.83%, P = .09) but this reduction was not significant. The median percent thrombus inhibition for treated cats was 100.0% at 4 hours and 91.4% at 12 hours. Plasma anti-Xa activity was not significantly correlated with thrombus formation.
Conclusions and Clinical Importance: This pilot study demonstrates that enoxaparin, when administered at a dosage of 1 mg/kg SC q12h, produces an antithrombotic effect in a venous statsis model in clinically healthy cats. Furthermore, this study demonstrates that anti-Xa activity is a poor predictor of enoxaparin's antithrombotic effect.     

The incretin effect in cats: comparison between oral glucose, lipids, and amino acids

Incretin hormones are secreted from the intestines in response to specific nutrients. They potentiate insulin secretion and have other beneficial effects in glucose homeostasis. We aimed to study the incretin effect in cats and to compare the effect of oral glucose, lipids, or amino acids on serum concentrations of insulin, total glucose-dependent insulinotropic peptide (GIP) and total glucagon-like peptide 1 (GLP-1). Ten healthy cats were used in a repeated measures design. Glucose, lipid, or amino acids were administered through nasoesophageal tubes on separate days. Blood glucose (BG) concentrations were matched between experiments by measuring BG every 5 min and infusing glucose intravenously at a changing rate. Intravenous glucose infusion with no prior treatment served as control. The incretin effect was estimated as the difference in insulin area under the curve (AUC) after oral compared with intravenous glucose. Temporal changes and total amount of hormone secretions were compared between treatment groups with the use of mixed models. Total glucose infused (TGI) at a mean dose of 0.49 g/kg resulted in slightly higher BG compared with 1 g/kg oral glucose (P = 0.038), but insulin concentrations were not significantly different (P = 0.367). BG and the TGI were not significantly different after the 3 oral challenges. Total GIP AUC was larger after lipids compared with amino acids (P = 0.0012) but GIP concentrations did not increase after oral glucose. Insulin and GIP concentrations were positively correlated after lipid (P < 0.001) and amino acids (P < 0.001) stimulations, respectively, but not after oral glucose stimulation. Total GLP-1 AUC was similar after all three oral stimulations. Insulin and GLP-1 concentrations were positively correlated after glucose (P = 0.001), amino acids (P < 0.001), or lipids (P = 0.001) stimulations. Our data indirectly support an insulinotropic effect of GIP and GLP-1. Potentiation of insulin secretion after oral glucose is minimal in cats and is mediated by GLP-1 but not GIP.     

Unilateral and Bilateral Congenital Sensorineural Deafness in Client-Owned Pure-Breed White Cats

Background: Congenital sensorineural deafness has been reported frequently in experimental mixed-breed white cats but there is a paucity of data on occurrence of deafness in client-owned pure-breed white cats.
Objective: To describe hearing status in client-owned pure-breed white cats.
Animals: Eighty-four pure-breed client-owned cats with white coat color of 10 registered breeds presented for routine hearing evaluation before breeding (1995–2008).
Methods: Hearing was assessed by click-evoked brainstem auditory evoked response.
Results: Overall deafness prevalence was 20.2%; 9 cats (10.7%) were bilaterally deaf and 8 cats (9.5%) were unilaterally deaf. There was no association between sex and deafness status ( P = .85). Deafness status was associated with iris color ( P = .04).
Conclusions and Clinical Importance: Congenital sensorineural deafness frequently occurs in pure-breed cats with white coat color. Unilateral sensorineural deafness was as common as bilateral deafness.     

Breed Dependency of Reference Intervals for Plasma Biochemical Values in Cats

Background: Reference intervals (RI) are pivotal in clinical pathology. The influence of breed on RI has been poorly documented in cats. Hypothesis/Objectives: RI for plasma biochemistry variables are breed‐dependent in cats. Animals: Five hundred and thirty‐six clinically healthy, fasted, client‐owned cats from 4 breeds: Holly Birman (n = 132), Chartreux (n = 129), Maine Coon (n = 139), and Persian (n = 136). Methods: Prospective observational study: Blood samples were collected from the cephalic vein into capillary tubes containing lithium heparin. Plasma glucose, urea, creatinine, total proteins, albumin, calcium, phosphate, sodium, potassium, chloride, and total CO₂ concentrations and the activities of alanine aminotransferase and alkaline phosphatase were assayed with a dry slide biochemical analyzer. RI were defined as central 95% intervals bounded by the 2.5th and 97.5th percentiles. Data were analyzed by a linear mixed effects model with type I error rate of 0.05. Results: A significant (P < .05) breed effect was observed for 9/13 variables. The magnitude of the differences between breeds could be clinically relevant for creatinine, glucose, and total protein. Age, body weight, sex, and housing conditions had significant (P < .05) breed‐related effects on different variables. Conclusions and Clinical Importance: Breed‐specific RI should be considered for cats.     

Effect of Weight Gain and Subsequent Weight Loss on Glucose Tolerance and Insulin Response in Healthy Cats

The effects of weight gain and subsequent weight loss on glucose tolerance and insulin response were evaluated in 12 healthy cats. Intravenous glucose tolerance tests (IVGTT) were performed at entry into the study, after a significant gain of body weight induced by feeding palatable commercial cat food ad libitum, after a significant loss of body weight induced by feeding a poorly palatable purified diet to discourage eating and promote fasting, and after recovery from fasting when body weight had returned to pre-study values and cats were eating commercial foods. A complete physical examination with measurement of body weight was performed weekly, a CBC and serum biochemistry panel were evaluated at the time of each IVGTT, and a liver biopsy specimen obtained 2 to 4 days after each IVGTT was evaluated histologically for each cat. Mean serum glucose and insulin concentrations after glucose infusion and total amount of insulin secreted during the second 60 minutes and entire 120 minutes after glucose infusion were significantly (P > .05) increased after weight gain, as compared with baseline. At the end of weight loss, cats had hepatic lipidosis and serum biochemical abnormalities consistent with feline hepatic lipidosis. There was a significant (P > .05) increase in mean serum glucose concentration and t_1/2, and a significant (P > .05) decrease in mean serum insulin concentration and the glucose disappearance coefficient (K) after glucose infusion for measurements obtained after weight loss, compared with those obtained after weight gain and at baseline. Insulin peak response, insulino-genic index, and total amount of insulin secreted during the initial 10 minutes, 20 minutes, and 60 minutes after glucose infusion were decreased markedly (P > .05), compared with measurements obtained after weight gain and at baseline. In addition, the total amount of insulin secreted for 120 minutes after glucose infusion was decreased markedly (P > .05) in measurements obtained after weight loss, compared with those obtained after weight gain. At the end of recovery, all cats were voluntarily consuming food, serum biochemical abnormalities identified after weight loss had resolved, the number and size of lipid vacuoles in hepatocytes had decreased, and results of IVGTT were similar to those obtained at baseline. These findings confirmed the reversibility of obesity-induced insulin resistance in cats, and documented initial deterioration in glucose tolerance and insulin response to glucose infusion when weight loss was caused by severe restriction of caloric intake.     

2013年-2015年西安宠物门诊家养猫泛白细胞减少症病例调查

猫泛白细胞减少症(FP)是由猫泛白细胞减少症病毒(FPV)引起的猫科动物的急性高度接触性传染病,临床上常以发热、呕吐、腹泻、脱水、肠炎以及白细胞极度减少为主要特征.本病传播速度快,对猫科动物危害极大.近年来,西安地区家养猫数量不断增加,患FP的病例也随之增多.为了解西安地区家养猫FPV感染和发病情况,为本病的防控提供基础资料,2013年7月~2015年7月,用猫泛白细胞减少症病毒检测试剂盒,对西安市部分宠物(动物)医院接诊的疑似FP病猫的467份粪便进行FPV检测,共检出阳性样品71份,占15.2%(71/467),其中2013年5份,2014年57份,2015年9份;阳性患猫中未免疫接种FPV疫苗的有70份,占98.6%(70/71).确诊病例中47.9%(34/71)临床出现呕吐症状,71.8%(51/71)出现腹泻症状.血液分析发现,84.51%的FPV感染猫的白细胞低于正常值;对71个患猫进行对症和支持治疗后存活率为83.1%(59/71).     

Effects of Exenatide on Plasma Glucose and Insulin Concentrations in Alpacas

Background: Exenatide is a degradation-resistant glucagon-like peptide 1 agonist used in the treatment of diabetes mellitus. It enhances the insulin response to hyperglycemia. Because of a poor insulin response, adult camelids are susceptible to hyperglycemia from stress, glucose administration, or energy metabolism disorders. Insulin often is administered to decrease plasma glucose concentration, but this approach has disadvantages such as the risk of hypoglycemia. Noninsulin medications targeting the incretin hormone pathway, such as exenatide, are providing alternate treatment options.
Hypothesis/Objectives: Exenatide will decrease plasma glucose and increase insulin concentrations in alpacas.
Animals: Six healthy adult alpacas.
Methods: After food was withheld for 8 hours, alpacas were given, on subsequent days in a randomly determined order, either 0.2 μg/kg of exenatide or similar volume of isotonic saline SC. Blood samples were collected before and 15, 30, 45, 60, 75, 90, 105, and 120 minutes after treatment. A rapid dextrose (0.5 g/kg) injection was given after the time 60 samples. Plasma glucose and insulin concentrations were measured at each time point.
Results: Alpacas had significantly ( P = < .001–.015) lower plasma glucose and higher insulin concentrations for the hyperglycemic period after receiving exenatide than after saline injections. Colic signs were observed in 5 of 6 alpacas treated with exenatide.
Conclusions and Clinical Importance: Exenatide appeared to increase insulin release and decrease plasma glucose concentrations in hyperglycemic alpacas. These findings are similar to findings in humans and could support therapeutic usage of exenatide in alpacas. However, induction of colic may limit practical application.     

Hyperglycaemia but not hyperlipidaemia decreases serum amylase and increases neutrophils in the exocrine pancreas of cats

The goal of the study was to determine whether hyperglycaemia or hyperlipidaemia causes pancreatitis in cats and to assess the effect of excess serum glucose and lipids on amylase and lipase activity. Ten-day hyperglycaemic and hyperlipidaemic clamps were carried out in five and six healthy cats, respectively. Ten healthy cats received saline and served as controls. The activity of amylase was below the normal range in 4 of 5 hyperglycaemic cats by day 10. The activity of lipase did not vary in any of the cats. Samples of exocrine pancreas were normal on histological examination, but the number of tissue neutrophils was increased in hyperglycaemic cats (P < 0.05). In a retrospective study 14 of 40 (35%) cats with naturally occurring diabetes mellitus had amylase activities below the reference range at the time of admission. Amylase activities normalised within 1 week of insulin therapy and subsequent glycaemic control. Lipase activity was increased in 26 of 40 (65%) diabetic cats and remained elevated despite glycaemic control. In conclusion, hyperglycaemia, but not hyperlipidaemia, increases pancreatic neutrophils in cats. However, because the histological morphology of the exocrine pancreas was normal, hyperglycaemia may play only a minor role in the pathogenesis of pancreatitis. Low amylase activities in diabetic cats may reflect an imbalance in glucose metabolism rather than pancreatitis.     

Serum glycated albumin: Potential use as an index of glycemic control in diabetic dogs

Measurements of serum fructosamine, glycated hemoglobin, and glycated albumin (GA) complement serum glucose concentration for better management of diabetes mellitus (DM). Especially, the serum fructosamine test has long been used for diagnosing and monitoring the effect of treatment of DM in dogs. However, fructosamine tests are currently not performed in veterinary medicine in Japan. GA and fructoasmine levels have been shown to strongly correlate. However, the clinical implications of using GA remain to be elucidated. Therefore, the purpose of the current study was threefold: 1) Determine whether GA% is altered by acute hyperglycemia in normal dogs, simulating stress induced hyperglycemia; 2) Demonstrate that GA% does not dynamically change with diurnal variation of blood glucose concentration in diabetic dogs; and 3) Investigate whether GA% is capable of providing an index of glycemic control for 1–3 weeks in diabetic dogs as is the case with diabetic human patients. Our study demonstrated that serum GA% remains very stable and unaltered under acute hyperglycemic conditions (intravenous glucose injection) and in spite of diurnal variation of blood glucose concentration. Furthermore, serum GA% can reflect long-term changes (almost 1–3 weeks) in blood glucose concentration and the effect of injected insulin in diabetic dogs.