Hypothyroidism in Dogs
Signs, Diagnosis, and Treatment
This article is for educational purposes only and does not promote or advertise any prescription-only veterinary medicine. Treatment decisions should always be made in consultation with a veterinary surgeon.
Hypothyroidism is one of the most common hormonal conditions seen in dogs. It occurs when the thyroid gland does not produce enough thyroid hormone, leading to a slowing of metabolism and widespread effects on the body.
- Caused by reduced thyroid hormone production
- Common signs include weight gain, lethargy, and skin changes
- Diagnosis is confirmed with blood testing
- Management involves long-term hormone replacement under veterinary supervision
What is hypothyroidism?
The thyroid gland plays a key role in regulating metabolism, energy levels, and many organ systems. In hypothyroidism, reduced hormone production slows these processes.
The most common cause is autoimmune destruction of thyroid tissue, although other causes can occur.
Common signs of hypothyroidism
- Weight gain
- Lethargy or reduced activity
- Hair thinning or loss
- Dry, thickened, or darkened skin
- Recurrent skin or ear infections
- Cold intolerance
Skin disease is often one of the first noticeable signs, and many cases are initially investigated for dermatological problems.
Dogs with hypothyroidism may benefit from additional skin and coat support alongside veterinary treatment.
How is hypothyroidism diagnosed?
Diagnosis is based on blood testing, typically measuring thyroid hormone (T4) levels and sometimes thyroid stimulating hormone (TSH).
Results must be interpreted carefully, as other illnesses and medications can affect thyroid values. Diagnosis should always be confirmed by a veterinary surgeon.
Treatment for hypothyroidism
Management of hypothyroidism involves replacing deficient thyroid hormone levels using levothyroxine.
Treatment plans are tailored to the individual patient, taking into account body weight, clinical response, and blood test results.
Most dogs show improvement in energy levels within a few weeks of starting treatment, although skin and coat changes may take several months to fully resolve.
Tablet formulations are commonly used, with dosing adjusted based on follow-up monitoring and clinical response.
Liquid formulations may be considered in cases where dosing flexibility or ease of administration is important.
Levothyroxine is a prescription-only veterinary medicine and should only be used under veterinary supervision.
Treatment selection and dosing decisions depend on individual patient factors and should always be made by the prescribing veterinary surgeon.
Regular blood testing is required, particularly during the early stages of treatment, to ensure appropriate dosing.
Long-term outlook
The prognosis for dogs with hypothyroidism is generally excellent when appropriately managed. Most dogs return to a normal quality of life with consistent treatment.
Ongoing monitoring is important to maintain stable hormone levels and adjust dosing where required.
Hypothyroidism requires diagnosis and ongoing monitoring by a veterinary surgeon. Treatment should always follow professional guidance.