Why Thyroid Health Matters in Dogs and Cats

The thyroid gland plays a critical role in regulating your pet’s metabolism, growth, and energy levels. When this small but powerful gland malfunctions, the impact can be felt throughout the body. Thyroid disorders—namely hypothyroidism in dogs and hyperthyroidism in cats—are common, particularly in middle-aged and senior pets.

At Memorial Villages Animal Hospital in Houston, Texas, we emphasize early detection and individualized treatment plans for pets with thyroid issues. Proactive care and regular wellness exams help identify these conditions before they cause lasting damage.

Why Are Regular Veterinary Visits Important?
 Preventive Testing for Senior Pets – Zoetis Petcare

Understanding Hypothyroidism in Dogs

What Is Hypothyroidism?

Hypothyroidism occurs when the thyroid gland doesn’t produce enough hormones, resulting in a slower metabolism. It’s most commonly diagnosed in middle-aged to older dogs and is relatively rare in cats.

Common Causes

  • Autoimmune thyroiditis (Lymphocytic thyroiditis): The dog’s immune system attacks its own thyroid tissue.
  • Thyroid atrophy or shrinkage of the gland.
  • Congenital issues or, more rarely, thyroid tumors.

Symptoms to Watch For

  • Unexplained weight gain without a change in appetite
  • Lethargy or reluctance to exercise
  • Hair thinning, dry coat, or symmetrical hair loss
  • Cold intolerance or frequent shivering
  • Chronic skin infections or ear problems
  • Slowed heart rate

More on Canine Hypothyroidism – Cornell Vet

Understanding Hyperthyroidism in Cats

What Is Hyperthyroidism?

Hyperthyroidism is the result of excessive thyroid hormone production, usually caused by a benign tumor on the thyroid gland. It is most commonly seen in cats over the age of 10.

Common Causes

  • Benign adenomas (non-cancerous tumors) are the primary cause.
  • Rarely, malignant tumors or dietary/environmental factors may contribute.

Symptoms to Monitor

  • Noticeable weight loss despite a ravenous appetite
  • Restlessness, irritability, or increased vocalization (Learn more: Common Cat Behavior Issues in Older Cats – ASPCA)
  • Vomiting or diarrhea
  • Increased heart rate or signs of hypertension
  • Poor coat quality or unkempt appearance
  • Increased thirst and urination

Learn more:
Hyperthyroidism in Cats – Cornell Feline Health Center
 Feline Hyperthyroidism Guidelines – AAHA

How Thyroid Disorders Affect Your Pet’s Health

Consequences of Untreated Hypothyroidism (Dogs)

  • Weight gain and reduced mobility
  • Behavioral changes such as depression or confusion
  • Increased risk of heart disease and reproductive issues
  • Dry, itchy skin or chronic infections

Consequences of Untreated Hyperthyroidism (Cats)

  • Severe muscle wasting
  • High blood pressure (hypertension)
  • Cardiac complications including heart murmurs and cardiomyopathy 
  • Potential thyroid storm, a dangerous spike in hormone levels

Heart Disease Diagnosis – Cummings Veterinary Medical Center

Diagnosing Thyroid Imbalances

For Dogs (Hypothyroidism)

  • Blood tests measuring total T4 and free T4 hormone levels
  • TSH (thyroid-stimulating hormone) tests help confirm diagnosis
  • Additional testing such as thyroid ultrasound or biopsy if tumors are suspected

For Cats (Hyperthyroidism)

  • Total T4 levels are typically elevated
  • Free T4 by equilibrium dialysis for ambiguous cases
  • Thyroid imaging or scintigraphy can identify the size and location of any growths

Ongoing diagnostics help assess response to treatment and adjust care plans accordingly.

Treatment Options for Thyroid Disorders

Treating Hypothyroidism in Dogs

  • Lifelong hormone replacement (levothyroxine) administered orally
  • Regular monitoring of T4 levels to ensure appropriate dosage
  • Visible improvement often occurs within weeks

Treating Hyperthyroidism in Cats

  • Oral medication (e.g., Methimazole) to reduce hormone production
  • Radioactive iodine therapy (I-131) for a permanent, non-surgical cure
  • Surgical thyroidectomy for some cases
  • Dietary management (e.g., iodine-restricted food)

Regular blood pressure checks and monitoring of kidney function are essential, especially in older cats undergoing treatment.

The Role of Preventive Care

Routine Screening Saves Lives

  • Senior pets should receive bloodwork that includes thyroid panels as part of their annual wellness exams.
  • Thyroid conditions can develop subtly; early detection often makes treatment more effective and affordable.

Preventive Testing for Senior Pets – Zoetis Petcare
 Why Are Regular Veterinary Visits Important?

Support for You and Your Pet

Thyroid disorders are manageable with proper veterinary care. Whether it’s a sluggish senior dog who just isn’t himself or a formerly aloof cat suddenly acting ravenous and restless, these symptoms may point to a treatable thyroid issue.

At Memorial Villages Animal Hospital, we’re here to help your pet live a longer, healthier life with diagnostic precision and compassionate, personalized treatment.

Concerned about your pet’s thyroid health? Contact us today to schedule a consultation or wellness screening.