STUDIES ON HYPOTHYROIDISM IN DOGS AND ITS THERAPEUTIC MANAGEMENT
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Date
2024-01
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SRI VENKATESWARA VETERINARY UNIVERSITY, TIRUPATI - 517 502. (A.P.) INDIA
Abstract
The present investigation was carried out at Veterinary Clinical Complex, NTR
College of veterinary science, Gannavaram from March to November 2023. The overall
occurrence of hypothyroidism was 0.45 per cent. Hypothyroidism was more common in
dogs aged above eight years (40.74%), intact males with Labrador Retriever as the most
susceptible breed. The total T4 and free T4 concentration hypothyroid dogs were 7.74 ±
0.60 nmol/L and 0.32 ± 0.04 ng/dL respectively which were significantly lower (P˂0.01)
when compared to healthy (34.86 ± 4.30 nmol/L). By considering RIA as gold standard,
the accuracy, sensitivity and specificity of CLIA in the estimation of total T4
concentration was 71.79, 29.63 and 94.12 per cent respectively.
The hypothyroid dogs exhibited dermatological manifestations in 88.88 per cent
of dogs, signs related to metabolism in 62.96 per cent, neuromuscular signs in 22.22 per
cent and reproductive disorders in 25.93 per cent and cardiovascular disorders in 7.41 per
cent.
The low voltage QRS complex was observed as the major ECG abnormality
(44.44%), tall T wave, electrical alternans, bradyarrhythmia’s and ST coving absence of
P-wave, atrial flutter and increased R wave amplitude were the other findings recorded.
Echocardiography in hypothyroid dogs revealed dilated cardiomyopathy and pleural
effusion in two dogs (13.33%) each, mitral regurgitation, pericardial effusion and left
ventricular enlargement were observed in three dogs (20.00%) each.
Pearson correlation revealed significant correlation (P<0.05) of total T4 (RIA)
with free T4 and TSH and was negatively correlated with total T3. Serum cholesterol
demonstrated highly significant correlation (P<0.001) with triglycerides and significant
correlation (P<0.05) with ALP.
Out of 27 dogs with hypothyroidism, 11 dogs (40.74%) were found to have
concurrent disorders, either single or mixed infections. One dog had concurrent diabetes
mellitus.
The hypothyroid dogs were treated with synthetic sodium Levo-thyroxine at an
initial dose of 20 µg/kg bodyweight administered once in a day and monitored regularly
at two weeks interval. The efficacy of therapy was studied based on clinical and
laboratory response.
Significant improvement (P < 0.01) in total T4 and free T4 was recorded after
therapy. Upon therapy, the mental activity was improved in all the dogs by six weeks,
weight reduction was evident in 85.71 per cent of the treated dogs by ten weeks and all
the dogs exhibited dermatological improvement by 12 weeks of therapy
The mean ± SE of haemoglobin (g/dL), PCV (%) and TEC (x106/µL) were
significantly lower (P<0.05) in hypothyroid dogs when compared to healthy control
which improved significantly (P<0.05) after therapy. After therapy, a highly significant
decline (P < 0.01) in mean ALP and triglycerides values was recorded. The serum
cholesterol (mg/dL) concentrations in hypothyroid dogs prior to therapy were
significantly higher (P < 0.01) than the healthy control. After therapy, a highly significant
decline (P < 0.01) in mean cholesterol values was recorded.
All the dogs achieved complete recovery by 12 weeks of therapy. The average
time taken for complete recovery was recorded as 70.00 days.