Is Your Dog Slowing Down? It Could Be Hypothyroidism

If your dog seems to be gaining weight, losing energy, or developing dry, flaky skin, it’s easy to chalk it up to age or the weather. But what if there’s something more going on?

At PetMed of Key West Veterinary Clinic in Dubuque, we frequently diagnose a condition called hypothyroidism—a common hormonal disorder in middle-aged to older dogs. Fortunately, it’s also very treatable with the right care.

Fun Fact: Dogs vs. Cats—Thyroid Edition

Here’s something interesting:

• Dogs are almost always hypothyroid (underactive thyroid)
• Cats are almost always hyperthyroid (overactive thyroid)

They’re total opposites when it comes to this gland! So if your dog has a thyroid problem, odds are, it’s because their thyroid is slowing down.

Signs of Hypothyroidism in Dogs

Because thyroid hormones control metabolism, an underactive thyroid can affect nearly every part of the body. Common symptoms include:

• Weight gain without increased appetite
• Lethargy or low energy
• Dry, dull coat or excessive shedding
• Flaky or thickened skin
• Hair loss, especially on the trunk and tail
• Cold intolerance (seeking warm places or shivering easily)
• Ear infections or skin infections that keep coming back
• Slow heart rate
• Behavioral changes like depression or anxiety

These signs tend to appear slowly and can easily be mistaken for aging—which is why testing is so important.

How We Test for Hypothyroidism

A standard total T4 test is a good screening tool, but it has limitations. T4 levels naturally fluctuate throughout the day and can be falsely low due to:

• Stress
• Illness
• Certain medications
• Normal daily variation (the “thyroid wave”)

To get a clearer picture, we use a more specific test called Free T4 (FT4), which measures the active thyroid hormone not bound to proteins. This helps us avoid overdiagnosing dogs who are simply at the low end of normal. If results are borderline or confusing, we may also test TSH (thyroid-stimulating hormone) for a more complete diagnostic picture.

How We Treat Hypothyroidism

Treatment is straightforward: a daily thyroid supplement (levothyroxine) given in pill or chewable form. Most dogs do extremely well on treatment, with energy levels, weight, and coat condition improving within a few weeks. We typically monitor your dog’s thyroid levels with bloodwork every few weeks at first, then every 6–12 months once we’ve found the right dose.

Don’t Let Your Dog Slow Down Without a Reason

If your dog is showing signs of hypothyroidism, don’t assume it’s just age or laziness. This is a real medical condition—and one we can manage easily with lifelong medication and monitoring. Call PetMed of Key West Veterinary Clinic in Dubuque today to schedule a thyroid screening. A simple blood test could be the key to a happier, healthier, more energetic dog!