Understanding Hypothyroidism in Dogs: Helping Your Dog Feel Like Themselves Again

At Audubon Family Veterinary Center, we understand how even the smallest changes in your pet's behavior can be concerning. Perhaps your dog has been slowing down, gaining a few pounds, or struggling with persistent skin and coat issues. These could all be subtle indicators of hypothyroidism, a common yet treatable condition that often affects middle-aged and senior dogs.

The encouraging news is that with the right care, dogs with hypothyroidism can regain their energy, playfulness, and happiness.

What Is Hypothyroidism?

Hypothyroidism develops when a dog’s thyroid gland doesn’t produce enough thyroid hormone, which is crucial for maintaining a healthy metabolism. When hormone levels are low, the body’s functions slow down, impacting energy, skin and coat health, and even organ function.

While any breed can be affected, hypothyroidism is most prevalent in medium to large dogs as they approach their middle or senior years. Cats are rarely affected, and when they are, it’s usually due to congenital conditions or post-treatment for hyperthyroidism.

Recognizing the SignsSince thyroid hormones influence various body systems, hypothyroidism can manifest differently in each dog. Common signs include:

• Weight gain despite a normal or reduced appetite

• Lethargy or decreased activity

• Dry, flaky skin or recurrent infections

• Thinning fur or hair loss along the sides or tail

• Sensitivity to cold

• Behavioral changes such as irritability or dullness

  
  

If left untreated, severe hypothyroidism can affect the heart, gallbladder, or nervous system. Fortunately, with a proper diagnosis, it’s highly manageable, and most dogs show significant improvement with treatment.

How We Diagnose It

To accurately diagnose hypothyroidism, specific blood tests are necessary since other health issues can affect thyroid hormone levels. We measure several values, including T4, Free T4, TSH, and Thyroglobulin autoantibodies, to confirm hypothyroidism and eliminate other mimicking conditions. This thorough approach ensures we provide the right treatment for the correct diagnosis.

Treatment and What to Expect

The primary treatment for hypothyroidism is a daily thyroid hormone supplement called levothyroxine. This medication replaces the hormone your dog’s thyroid no longer produces naturally. It’s administered orally, usually once or twice a day, and is generally well tolerated.

Most dogs begin to show improvement quickly, with energy levels and alertness often returning within a couple of weeks. Skin and coat health may take a month or two to fully improve. Though side effects are rare, if the dosage is too high, symptoms may resemble hyperthyroidism, such as restlessness or increased thirst. Regular monitoring helps us adjust the dosage to keep your dog in optimal health.

Monitoring and Long-Term Care

Managing hypothyroidism is a lifelong commitment, but it becomes routine once your dog’s hormone levels stabilize. After starting medication, we recheck bloodwork about 4–8 weeks later, taking samples a few hours after the morning dose. Once stable, follow-up testing is usually conducted every 6–12 months to ensure the dose remains effective.

With consistent care, most dogs live full, happy lives, enjoying more energy, clearer skin, and a softer, healthier coat.

Supporting Your Dog’s Overall Health

A dog with hypothyroidism benefits from the same essentials as any healthy pet:

• A balanced, high-quality diet

• Regular exercise

• Routine veterinary visits and lab work

• Plenty of rest and a stress-free environment

As your dog begins treatment, you may notice subtle changes — brighter eyes, more energy, and that familiar spark returning. It’s one of the most rewarding transformations we witness.

The Bottom Line

Hypothyroidism may sound complex, but it’s one of the most manageable conditions in veterinary medicine. With medication, regular check-ins, and a little patience, most dogs regain their vitality and enjoy long, healthy lives. At Audubon Family Veterinary Center, we’re here to support you every step of the way — from diagnosis to lifelong management — ensuring your dog feels like themselves again.