Understanding Hypothyroidism in Dogs

What is Hypothyroidism?

Hypothyroidism happens when your dog’s thyroid gland doesn’t produce enough thyroid hormone. This hormone controls metabolism — the process that keeps every organ and system running efficiently. When levels are low, the body slows down, leading to a variety of symptoms that can appear gradually.

Common Signs of Hypothyroidism

Dogs with low thyroid function may show one or more of the following signs:

  • Weight gain without eating more
  • Low energy or sleeping more than usual
  • Dull, thin, or brittle coat
  • Hair loss, often on both sides of the body or tail
  • Thickened, darkened skin
  • Intolerance to cold
  • Slow heart rate or muscle weakness
  • Behavior changes — more withdrawn, less playful

How We Diagnose It

We confirm hypothyroidism through blood testing. A basic thyroid screen may show a low T4, but to confirm, we often run a full thyroid panel that includes free T4 and TSH levels. Sometimes other illnesses can lower thyroid levels temporarily, so accurate diagnosis matters before starting lifelong treatment.

Treatment

Treatment is lifelong thyroid hormone replacement (levothyroxine). This is a simple oral tablet given once or twice daily depending on your dog’s needs.

You’ll typically start to see improvements in:

  • 2–4 weeks: Energy and activity
  • 6–8 weeks: Coat and skin improvement

It’s very important to give the medication consistently at the same time each day, and do not stop without consulting your veterinarian.

Follow-Up and Monitoring

After starting treatment, we’ll recheck thyroid levels in:

  • 4 weeks after the first dose
  • Then every 6–12 months once stable

We may adjust the dose based on bloodwork and how your dog feels.

Long-Term Outlook

With proper medication and monitoring, most dogs with hypothyroidism live full, happy, and normal lives. If untreated, the condition can cause serious complications including obesity, lethargy, skin infections, and heart issues — but with treatment, those problems are avoidable.

Quick Summary

  • Hypothyroidism = low thyroid hormone = slow metabolism
  • Symptoms: weight gain, tiredness, skin/coat issues
  • Diagnosed through bloodwork
  • Treated with daily medication for life
  • Recheck blood every 6–8 weeks until stable, then every 6–12 months

If you have any additional questions, please call us at 319-277-7675 or email us at [email protected]. We would be happy to assist you.