Comprehensive Guide to Thyroid Disorders in Dogs and Cats

Thyroid disorders are common yet often misunderstood conditions that can significantly impact your pet’s health and well-being. The thyroid gland plays a key role in regulating metabolism, energy levels, and organ function. When this system is disrupted—whether by underproduction (hypothyroidism) or overproduction (hyperthyroidism) of thyroid hormones—your pet may experience a wide range of symptoms that affect their behavior, appetite, and appearance.

At Pinedale Animal Hospital in Pinedale, Wyoming, we are dedicated to helping pet owners recognize the signs of thyroid disorders early and offering effective treatment options tailored to each pet’s needs.

Why Thyroid Health Matters

The thyroid gland, located in the neck, produces hormones that regulate the body’s metabolic rate. When hormone levels are too low or too high, the effects can be far-reaching—impacting the heart, weight, coat quality, digestion, and even mood.

  • Hypothyroidism: Commonly seen in middle-aged to older dogs, this condition results from insufficient thyroid hormone production, slowing the body’s processes.
  • Hyperthyroidism: Seen primarily in senior cats, this condition is caused by excess hormone production, leading to increased metabolic activity.

Understanding these conditions is the first step toward managing them effectively.

Pinedale Animal Hospital’s Role in Thyroid Care

Our veterinary team is experienced in the diagnosis, treatment, and long-term management of thyroid disorders. We use advanced diagnostic tools, bloodwork analysis, and ongoing monitoring to ensure your pet receives accurate care every step of the way. Explore our services.

Understanding Hypothyroidism in Dogs

What Is Hypothyroidism?

Hypothyroidism occurs when the thyroid gland doesn’t produce enough hormones, resulting in a slowed metabolism. This condition is most often diagnosed in middle-aged and older dogs.

Common Causes

  • Lymphocytic thyroiditis – An autoimmune condition where the immune system mistakenly attacks the thyroid gland.
  • Idiopathic atrophy – Gradual shrinkage of thyroid tissue over time.
  • Iodine deficiency or thyroid tumors (less common causes)

Symptoms of Hypothyroidism

  • Unexplained weight gain despite normal or reduced food intake
  • Lethargy or decreased interest in physical activity
  • Cold intolerance, shivering, or seeking warm places
  • Dry, flaky skin and hair thinning, especially on the tail or flanks
  • Recurrent skin or ear infections due to weakened immune response
    More on canine hypothyroidism – Cornell Vet

Understanding Hyperthyroidism in Cats

What Is Hyperthyroidism?

Hyperthyroidism results from an overactive thyroid gland producing too much hormone, increasing metabolism. It is most frequently seen in older cats and is rare in dogs.

Common Causes

  • Benign adenomas – Non-cancerous tumors in the thyroid gland
  • Thyroid carcinoma – Less common, but more serious, in dogs

Symptoms of Hyperthyroidism

Diagnosing Thyroid Disorders

How We Diagnose Hypothyroidism

  • Blood tests measuring total T4 and TSH levels
  • Advanced diagnostics, including thyroid ultrasound or biopsy if tumors are suspected

How We Diagnose Hyperthyroidism

  • Elevated T4 levels are the primary indicator
  • Imaging (ultrasound or scintigraphy) may be used to detect thyroid nodules
  • Ongoing monitoring to evaluate treatment progress and detect complications
    AAHA Guidelines for Feline Hyperthyroidism

Why Routine Wellness Exams Matter

Annual exams with blood screening help us detect subtle thyroid changes before symptoms escalate. Learn why regular vet visits matter.

Treatment Options for Thyroid Disorders

Managing Hypothyroidism in Dogs

  • Lifelong hormone replacement therapy (levothyroxine) is the standard treatment
  • Regular follow-ups to adjust medication doses based on thyroid levels and symptom control

Managing Hyperthyroidism in Cats

  • Oral medication (e.g., Methimazole) to reduce thyroid hormone production
  • Radioactive iodine therapy (I-131) – A highly effective, often permanent, treatment that destroys overactive thyroid cells
  • Surgical removal of the thyroid gland, typically for localized adenomas
  • Ongoing monitoring for blood pressure, kidney function, and T4 levels throughout treatment

Preventative Care and Long-Term Management

Regular Screening for Senior Pets

Breed-Specific Considerations

Some breeds are more predisposed to thyroid disorders:

  • Hypothyroidism: Golden Retrievers, Doberman Pinschers, Cocker Spaniels, Boxers
  • Hyperthyroidism: Common in older domestic short-haired cats

When to Contact Your Veterinarian

Watch for These Signs

If your pet is showing any of the following signs, it may be time to schedule a thyroid evaluation:

  • Dogs: Lethargy, weight gain, hair loss, skin infections
  • Cats: Weight loss, hyperactivity, increased appetite, vomiting

Support at Pinedale Animal Hospital

Our team provides personalized care, accurate diagnostics, and comprehensive treatment plans for managing thyroid health. If you’re concerned about your pet’s thyroid function, contact us today or request an appointment.

Supporting Lifelong Thyroid Health

Thyroid disorders are manageable with early detection and consistent care. Whether your pet is slowing down or showing signs of hyperactivity, don’t ignore the changes—your vet can help identify the underlying issue and guide you through treatment.

At Pinedale Animal Hospital, we’re here to help your pet thrive. From diagnosis to long-term management, we offer the tools and support you need to keep your companion feeling their best—today and for years to come.