2016 ACVIM Forum Research Abstract Program

Medical records for dogs in which an ACTH stimulation test had been performed for a clinical suspicion of hypoadrenocorticism between 2005 and 2015 were retrospectively reviewed. Dogs that had received treatment for hyperadrenocorticism or recent glucocorticoid therapy were excluded. Five hundred and fourteen dogs met inclusion criteria, including 163 dogs with hypoadrenocorticism (post-ACTH stimulated cortisol concentration ≤55 nmol/ L). An ROC curve was constructed for basal cortisol concentrations using commercially available software. The area under the ROC curve was 0.991. The ROC curves were nearly identical when evaluating dogs with and without electrolyte abnormalities. Accuracy was optimal at 22 nmol/L, which provided a sensitivity and specificity of 96.9% and 95.7%, respectively. At cut-offs of 55 nmol/L and 4 nmol/L, sensitivity and specificity were 99.4% and 99.7%, respectively. Using a previously estimated prevalence of 15%, cut points of 55 nmol/L and 4 nmol/L resulted in negative and positive predictive values of 99.8% and 97.9%, respectively. Even at lower prevalence rates, positive predictive values remained high at low cut points. Results of this study reaffirm the high sensitivity and negative predictive value of basal cortisol concentrations for the diagnosis of hypoadrenocorticism. However, the high specificity and positive predictive values at low cut points could be of major importance for veterinary practitioners. Prospective studies are needed to further substantiate these findings. Congenital hypothyroidism (CH) is associated with significant morbidity and mortality in pediatric felines. Thyroid hormones (TH) are essential for normal development of the nervous and skeletal systems. The paucity of information on TH levels and the inability to identify early histopathologic changes has led to CH underdiagnosis. The literature on TH levels in kittens is sparse and incongruent, comprised of mostly case reports. References state kitten total thyroxine (TT4) levels are 2 to 3 times higher than the adult cat TT4 level. They also make the assumption free thyroxine (fT4) levels are higher than the adult cat. An abstract was previously presented showing kitten TH levels did not exceed the adult cat normals. These values were measured with assays that are no longer used. The normal pediatric TH levels must be evaluated with the newer and currently available assays. The purpose of this study was to determine the TT4, fT4, total tri-idiothyronine (T3), free tri-idiothyronine (fT3) and thyroid stimulating hormone (TSH) levels in healthy kittens aged 2 through 16 weeks measuring levels at weekly intervals using the current available diagnostic methods.