Secondary hypothyroidism in a Labrador bitch

A Labrador bitch was brought to the Referral Veterinary Polyclinic, Indian Veterinary Research Institute for treatment of excessive weight gain in spite of a minimal maintenance diet. Clinical examination revealed dullness and lethargy, unwilling to exercise, ataxia, tendency to feel comfort in the sun and respiratory distress on exercise; excessive amount of fat covering the ribs, neck, spine, base of tail, hips, and along the para lumbar area; absence of waist and abdominal tuck and the body condition score (BCS) was computed as 9.0 on a nine point scale. ECG revealed sinus rhythm (Heart rate 120 beats/minute) and low amplitude of ‘P’ (0.15 mV). Low values of T₃ (17.0 ng/dl), T₄ (0.2μg/dl) and TSH (0.08μ IU/ml) were noted. Clinical signs, BCS and low values of T₃, T₄ and TSH led to the diagnosis of secondary hypothyroidism. The bitch was treated with thyroxin and a commercially available formulated diet.

Primary hypothyroidism of varied etiology is frequently encountered in dogs. However, cases of secondary hypothyroidism have not been reported with the same frequency. The present paper reports a case of secondary hypothyroidism in an adult Labrador bitch.