Hyperthyroidism in Dogs
Understanding Your Dog’s Thyroid Health
Thyroid hormones also play an important role in:
- Mental alertness
- Nerve function
- Heart health
- Skin and coat quality
At Elgar Road Vet, our Box Hill veterinarians regularly diagnose and manage hypothyroidism in dogs.
What Is Hypothyroidism?
Hypothyroidism occurs when the thyroid gland becomes underactive and does not produce enough thyroid hormone. It most commonly affects middle-aged to older dogs. It is often underdiagnosed because the signs can be subtle and are easily mistaken for “normal ageing.”
Signs of Hypothyroidism
Because thyroid hormone influences so many body systems, the symptoms can vary.
- Weight gain without an increase in appetite
- Lethargy or sleeping more than usual
- Reluctance to exercise
- Dry or flaky skin
- Excessive shedding
- Hair thinning (often along the body or tail)
- Darkening (increased pigmentation) of the skin
- Appearing dull or less engaged
- Reduced enthusiasm
- In severe cases, weakness, slowed heart rate, and low blood pressure
In approximately 95% of cases, hypothyroidism is caused by gradual, often symptomless damage to the thyroid gland. While the underlying cause is frequently unknown, the good news is that diagnosis and treatment are straightforward.
How Is Hypothyroidism Diagnosed?
Diagnosis involves a simple blood test measuring thyroid hormone levels (Total T4). In some cases, additional testing — such as measuring Thyroid Stimulating Hormone (TSH) — is required to confirm the diagnosis. Because many signs overlap with normal ageing or other conditions, routine blood screening is extremely valuable, particularly in middle-aged and senior dogs. Regular wellness blood tests allow us to detect conditions like hypothyroidism early — often before clinical signs become significant — and begin treatment sooner for better long-term outcomes.
Treatment
Treatment involves daily thyroid hormone supplementation for life. The medication is safe, effective, and generally very well tolerated.
- Improved energy and alertness within 3–4 weeks
- Gradual improvement in coat quality and skin health over 6–8 weeks
