The interpretive contribution of the baseline serum cortisol concentration of the ACTH stimulation test in the diagnosis of pituitary dependent hyperadrenocorticism in dogs.

BACKGROUND: Current recommendation for performing the ACTH stimulation test (ACTHST) for diagnosis of hyperadrenocorticism (HAC) advocates the collection of baseline serum cortisol concentration (BC), but no references for interpretation of its results exist. OBJECTIVE: Evaluate the contribution of BC of the ACTHST to the diagnosis of HAC. ANIMALS: Fifty-four dogs were evaluated for suspected HAC at a referral hospital. METHODS: Records of dogs that had been evaluated by ACTHST for suspected HAC were reviewed. Receiver operator characteristics (ROC) analyses were used to assess the performance of BC, post-stimulation serum cortisol concentrations (PC), post-to-baseline cortisol concentration difference (DeltaC) and quotient (RatioC) for the diagnosis of HAC by comparing the area under the ROC curve (AUC) of PC to each of the other tests. RESULTS: The AUC of PC (95% confidence interval [CI]: 0.92; 95% CI, 0.81-0.98) was significantly higher than AUCs of BC (0.70; 95% CI, 0.56-0.82; P = .01) and RatioC (0.55; 95% CI, 0.41-0.69; P < .001), and was not significantly different from AUC of DeltaC (0.86; 95% CI, 0.74-0.94; P = .09). An optimal cutoff value of 683 nmol/L (24.8 µg/dL) for PC yielded a sensitivity of 86% and a specificity of 94%, respectively, and a cutoff value of 718 nmol/L (26.0 µg/dL) yielded a specificity of 100% with of 81% sensitivity for the diagnosis of pituitary-dependent HAC. CONCLUSION AND CLINICAL IMPORTANCE: The PC had good discriminatory ability for the diagnosis of HAC. It was comparable to DeltaC, whereas BC and RatioC were ineffective. Current recommendations to collect samples for BC appear redundant.

Alpha-chloralose poisoning in dogs and cats: a retrospective study of 33 canine and 13 feline confirmed cases.

Alpha-chloralose (AC) is an anaesthetic compound also used as a rodenticide, and has dose-dependent central nervous system mixed effects of excitation and depression. The objectives of this study were to detail the clinical and clinicopathological characteristics, as well as the treatment and prognosis, of AC toxicosis in dogs and cats. Medical records were retrospectively reviewed for AC poisoning between the years 1989 and 2004, and 33 dogs and 13 cats were included in the study. The most common clinical signs were seizures, muscle tremor, hyperaesthesia, hypothermia, salivation, myosis, stupor, coma and ataxia. Coma was more common, while salivation and ataxia were less common in cats compared to dogs. Although hypothermia was very common, especially in cats (90.9%), hyperthermia was frequently observed in dogs (21%). Treatment in all patients was supportive and symptomatic, and the most commonly used anticonvulsants were diazepam and barbiturates; however, severe unresponsive seizures in three dogs had to be controlled with inhalant gas anaesthesia. The hospitalisation period was 1-3 days, and the overall mortality rate was 6.5%. Alpha-chloralose poisoning seems to have a favourable prognosis in dogs and cats.

Increased serum leptin and insulin concentrations in canine hypothyroidism.

Serum concentrations of leptin and insulin were compared between gender-matched hypothyroid (n=25) and healthy (n=25) client-owned dogs within comparable age and body condition score (BCS) ranges. Fasted blood samples were collected from each dog and analysed for glucose, cholesterol, triglyceride, leptin and insulin concentrations. Leptin and insulin concentrations were significantly higher in the hypothyroid compared to normal dogs (P=0.006 and P=0.001, respectively) following adjustment for potential confounders. A nearly significant (P=0.051) interaction with BCS was found in the association between hypothyroidism and leptin. Leptin concentrations were significantly higher in hypothyroid dogs compared to normal dogs, in separate analyses for BCS 6 (P=0.036) and 7 (P=0.049). There was no significant difference in glucose concentration between the hypothyroid and normal groups (P=0.84) following adjustment for BCS. This study showed that canine hypothyroidism is associated with increased serum leptin and insulin concentrations, neither of which may be attributed to obesity alone.