Dermatological manifestations of hypothyroidism in a dog and its management.
Hypothyroidism is a common canine endocrinopathy. Thyroid hormone is needed for initiation of anagen hair follicles, regulation of cornification process and sebaceous gland secretion (Jackson and Marsella, 2012). The plethora of clinical signs, affecting skin are dry, dull and brittle hair coat, scaling, lack of hair regrowth after clipping, alopecia on bridge of nose, tail and friction areas with hyperpigmentation.
History and Clinical findings
A two year old male spitz dog was brought with chronic generalized skin lesions with scales and erythematous lesions on the skin. The dog was normal in behavior and other vital signs such as heart rate and respiratory rates were within normal limits. The owner reported normal appetite.
On clinical examination the hair loss was restricted to trunk and tail. Scales were noticed with hyperpigmentation of tail and inguinal region. There was no pruritus. Lichenification was noticed in some affected areas (Fig. 1). The skin scraping was negative for ectoparasites and the tape impression was negative for Malassezia pachydermatis.
The diagnosis of hypothyroidism manifested as skin affections, is based on clinical signs viz. bilateral truncal alopecia with rat tail, seborrhea and recurrent pyoderma (Rosychuk, 1997).
Hairloss occurs in bilaterally symmetrical pattern initially in friction areas such as tail and around the neck. Pruritus is uncommon unless there is concurrent Malassezia infection or superficial pyoderma (Rosychuk, 1997).
Measurement of serum total [T.sub.4] remains useful test for diagnosing hypothyroidism. Normal serum total [T.sub.4]([tT.sub.4]) in dogs is > 2 [micro]g/dL.
In the present case the serum [tT.sub.4] was 0.5 pg/dL which favoured diagnosis of hypothyroidism associated with chronic alopecia.
The case was diagnosed hypothyroid and treatment was initiated with levothyroxine @ 22 [micro]g/kg (Tabs. Eltroxins[R] 100 pg) body weight (Feldman and Nelson, 1996).
There was complete hair growth within two months. After complete hair growth the owner discontinued the treatment which resulted in recurrence of the skin lesions. The owner was adviced to continue medication.
In a dog with classical signs of hypothyroid skin problem, estimation of serum [tT.sub.4] concentration below normal may all that is required for a tentative diagnosis and response to treatment with levothyroxine a confirmative diagnosis. Once daily therapy results in good clinical response. The dog should be monitored for recurrence of the condition. Recurrence warrants re-estimation of [tT.sub.4] and dose adjusted accordingly.
Successful treatment of a dog presented with chronic bilateral alopecia with Levothyroxine is presented.
Feldman E.C. and Nelson R.W. (1996). Canine and Feline Endocrinology and Reproduction, 2nd Edn., W.B. Saunders, Philadelphia, p. 68-117.
Jackson Hilary and Marsella Rosanna (2012). BSAVA Manual of Canine and Feline Dermatology. 3rd Edn., Gloucester, BSAVA, p. 94-95.
Rosychuk, R.A.W. (1997). Dermatologic manifestations of canine hypothyroidism and the usefulness of dermatohistopatholgy in establishing a diagnosis. Canine Practice. 22: 25-26.
C. Jayanthy (1), M. Sandhya Bavani (2), B. Nagarajan (3) and P. S. Thirunavukkarasu (4)
Department of Clinics
Madras Veterinary College
Tamil Nadu Veterinary and Animal Sciences University
Chennai--600007 (Tamil Nadu)
(a)--Brand of GSK Pharma, Mumbai
(1.) Assistant Professor and Corresponding author: E-mail: firstname.lastname@example.org
(2.) Post Graduate Scholar
(3.) Professor, Dept. of Veterinary Clinical Medicine, Ethics and Jurisprudence
(4.) Professor and Head
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|Title Annotation:||Short Communication|
|Author:||Jayanthy, C.; Bavani, M. Sandhya; Nagarajan, B.; Thirunavukkarasu, P.S.|
|Date:||Jul 1, 2013|
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