Canine hypothyroidism: avoiding over diagnosing the condition

In Pract. Mar 2022;44(2):68-75. 22 Refs

Susanna Spence¹

¹ North Downs Specialist Referrals, Bletchingley RH1 4QP, UK.

Author Abstract

Background: Hypothyroidism is one of the most commonly treated endocrine disorders in dogs; however, the diagnosis of this condition can be challenging, potentially leading to misdiagnosis. The clinical signs of hypothyroidism are vague and non-specific, as are the routine haematological and biochemical changes. When assessing the thyroid axis, the classical finding of decreased total thyroxine and increased thyroid-stimulating hormone is highly specific for the diagnosis of hypothyroidism, but has less good sensitivity. Although numerous other tests are available, a basic understanding of thyroid gland physiology and thyroid test methodology is needed to be able to use each test and interpret the results correctly.

Aim of the article: This article discusses how to confidently diagnose the condition, explaining how clinicians need to consider the clinical signs, routine clinicopathological changes and thyroid hormone concentrations together, rather than in isolation.

Article Tools:

Email to me

Archives Highlights:

Impacts from Wildfires on Livestock Health and Production: Producer Perspectives.
While dairy producers reported no direct impacts from the fires, beef, sheep, and goat producers were impacted by evacuations and pasture lost to fires. Only beef producers reported losses due to burns and burn-associated deaths or euthanasia. Dairy, beef, sheep, and goat producers observed reduced conception, poor weight gain, and drops in milk production. All but dairy producers also observed pneumonia. Lower birthweights, increased abortion rates, and unexplained deaths were reported in beef cattle, sheep, and goats.

Diagnostic value of liver function tests and ultrasonography in dogs with suspected congenital portosystemic shunts.
Fasting ammonia (FA) had the best combined sensitivity and specificity (77.4 and 93.3%, respectively) to diagnose congenital portosystemic shunt (cPSS). The sensitivity and negative predictive value were 100.0% for paired serum bile acids (SBA), making paired SBA the best test to exclude cPSS in this population. Sensitivity and specificity of abdominal ultrasound were 80.8 and 90.0%, respectively.

Daytime and nocturnal activity in treated dogs with idiopathic epilepsy compared to matched unaffected controls.
Dogs with idiopathic epilepsy (IE) treated with antiepileptic drugs (AEDs) had an 18% average lower baseline activity level compared to control dogs. The combination of phenobarbital and potassium bromide (KBr) was associated with an average 28% decrease in activity in dogs with IE compared to control dogs. Mean sleep scores were not significantly different in dogs with IE receiving AEDs compared to control dogs. However, higher dosages of KBr were associated with lower sleep scores.

Cuterebriasis in Dogs and Cats
The typical manifestation of a bot infestation is a seeping, cutaneous nodule (furuncular lesion) that may be mistaken for an abscess. These lesions are most often found near the head, along the neck, or extending caudally along the shoulders, thorax, or sides.

Top 5 Tips for Interpreting Heartworm Test Results
It is commonly believed that heartworm disease can be diagnosed based on a simple positive or negative in-clinic test result; however, this is not always true when testing dogs and is less accurate in cats. Interpretation of a heartworm antigen test is only one component of an accurate heartworm diagnosis; a variety of testing modalities may be required. Testing for the presence of antigens and microfilariae is recommended in dogs; diagnosis in cats usually requires additional testing (eg, antibody testing, radiography). These are the top 5 scenarios encountered when diagnosing heartworm disease in dogs and cats.