Previous Treatment with Trilostane and Levotiroxin in Subdosis Difficult the Diagnosis of Canine Hypothyroidism

Background: hypothyroidism is a disease of clinical importance that causes multisystem disorders, which can be confused with other endocrinopathies. Rapid and accurate diagnosis is necessary in order to avoid worsening of the clinical manifestation. The use of drugs in a wrong way can directly imply the difficulty of the diagnostic approach, since they may causechanges in the biochemical profiles, which are of great importance as markers in diseases of animals with low thyroid function.Case: The case reports a German Spitz male, one year old and six months old, neutered, who presented bilateral do not cause itching alopecia, being treated by another professional for endocrine and fungal affections. In this same medical appointment were neglected biochemical and hematological profile exams. The exams that had been performed were skin scrapings,which showed growth of fungi and bacteria, besides the measurement of thyroid hormones as TSH, T4L (T4 free) e T3, and also the low-dose dexamethasone suppression test. Based on the findings the therapy instituted by such professional was the administration of itraconazole (ITL®), levothyroxine sodium (compounded drugs) and trilostane (compounded drugs). With absence of clinical improvement, the guardian came to the hospital veterinary, in search of a second diagnostic opinion, where during the collection of information at the time of the anamnesis the patient presented lethargy, drowsiness and absence of hair on both sides. During the clinical examination, the animal presented mild bradycardia and a slightly diminished rectal temperature; in the dermatological evaluation the presence of pup pelt, cutaneous hyperpigmentation and hair thinning in the abdominal area were noted. From this evaluation, hematological exams were requested, which had altered the presence of lymphocytosis, and biochemical tests, where changes in the cholesterol and triglyceride levels were expected, but they were within the normal range. Hormone measurement showed decreased TSH and T4L levels within the reference range. Thyroid ultrasonography demonstrated a hypoplastic gland, while the assessment of abdominal organs were preserved. Based on this, the new therapy instituted was the increase of levothyroxine sodium (Puran®) dose with the withdrawal of other drugs that were being administered to the patient. Over the course of five months, the tutor returned because of lack of improvement in the condition, where he returned to present symptoms such as drowsiness, apathy and indisposition. Thus, a new battery of tests was requested, where the biochemical and hormonal parameters were within the normal range. Due to TSH being within normal, it was decided to change the medication for another version of human levothyroxine sodium (Synthroid®), which has been presenting satisfactory results so far.Discussion: In cases of patients, even when young, when they present bilateral symmetrical alopecia, complementary exams such as scraping of the skin and hair, trichrome and fungal culture, together with hemogram and biochemical profile, are necessary for discarding of endocrinopathies other than hypothyroidism. Treatments instituted with drugs such as trilostan cause changes in laboratory tests, which may make diagnosis difficult. Treatment with levothyroxine sodium expected in patients with hypothyroidism, and serum TSH and T4L levels should be monitored for evaluation of treatment efficacy. The present study demonstrated that the inadequate treatment made diagnosis difficult due to hematological andbiochemical alterations.Keywords: alopecia, dog, endocrine dermatopathy, hypothyroidism, levothyroxine, trilostane