Recent Advances in Diagnostic Procedure for Endocrine Disorders in Dogs and Cats

Abstract

There are 5 most common endocrine disorders affecting dogs and cats of different age groups. The organs affected are adrenals, thyroid and endocrine pancreas. The disease state of these organs is generally brought about by very similar pathomechanism leading to hormone overproduction or underproduction. Pituitary induced bilateral adrenocortical hyperplasia also known as pituitary dependent Cushing’s disease (PDH) accounts for 85% of all cases in dogs. There are two important hormone assay tests that can be done for the diagnosis and confirmation of Cushing’s syndrome viz. ACTH stimulation test and Low-dose dexamethasone suppression test (LDDST). ACTH stimulation test sensitivity is 85-95% for PDH but 60% for ADH. Majority of HAC cases are PDH. However, sensitivity for LDDST test is about 85-100% for ADH but lower in PDH. ACTH-stimulation test is the only diagnostic and is very reliable test for hypoadrenocorticism (Adisson’s disease). Hyperthyroidism is the most common feline endocrinopathy, affecting around 10% of older cats. Feline hyperthyroidism is usually easily diagnosed by the demonstration of elevated total thyroxine (tT4) or free thyroxine (fT4) concentration. Primary hypothyroidism occurs commonly in dogs and is usually associated with thyroid atrophy or lymphocytic thyroiditis. Serum concentration of fT4 is the most sensitive and specific single test for diagnosis of hypothyroidism. The combination of TT4 and canine specific c-TSH data also allow a more reliable evaluation of a dog’s thyroid status. Diabetes mellitus is now considered as one of the most common endocrinological disorders in dogs with estimated prevalence between 0.3-1.3 percent of the canine population. The most common form of DM in dogs is type 1 and it has been demonstrated that the majority of diabetic cats (80 to 90%) suffer from diabetes mellitus (DM), similar to type II in humans. The use of glycosylated haemoglobin (HbA1c) levels for the assessment of long term control of DM can be used in dogs and cats but warrant further validation.