Thyroid function evaluation in canine dermatoses

Abstract

Prevalence of hypothyroidism was studied among the dogs presented with dermatological problems at the University Veterinary Hospitals, Mannuthy and Kokkalai, during the period from June 2004 to May 2005. Among 1,233 dermatological cases presented, hypothyroidism accounted for 1.23 per cent (16 cases) Dogs between the age group of seven to ten years were more frequently affected and no significant differences in the incidence rate between male and female dogs were observed. Hypothyroidism was recorded more in German Shepherd breed followed by Dachshunds. Low serum thyroxine (T4) and high thyroid stimulating hormone (TSH) level with normal or low normal T3 levels were observed in the hypothyroid dogs. The most common dermatological changes exhibited by hypothyroid dogs included seborrhea, alopecia of tail and around the neck, bilaterally symmetrical pattern of hair loss and coat changes such as dryness, dullness, dandruff, scaliness, coarseness and sparseness. A significant increase in serum cholesterol concentration was observed in the affected dogs. Serum enzymes such as alkaline phosphatase and gamma glutamyl transferase were showed elevation in few cases. Replacement therapy using Eltroxin was found to be effective in treating hypothyroidism. A minimum of one month was needed to evaluate the therapeutic response. Four out of six (66.66 per cent) confirmed cases of hypothyroidism showed an excellent response to replacement therapy.