Hypothyroidism in Dogs

A complete guide on hypothyroidism for dog owners


This article is written by Pet Circle's qualified veterinarian, Dr Carla Paszkowski, BVSc (Hons)

Has your dog been diagnosed with Hypothyroidism? Or perhaps you are a prospective puppy owner researching your favourite dog breed, but have discovered they are a breed prone to developing Hypothyroidism and want to prepare yourself? This guide should provide you with everything you need to know about Hypothyroidism in dogs.


1. What is Hypothyroidism?

2. Which dog breeds are prone to Hypothyroidism?

3. Symptoms of Hypothyroidism

4. Diagnosis of Hypothyroidism

5. Treatment of Hypothyroidism

6. The Best Diet for Hypothyroidism

7. Supplements for Hypothyroidism

What is Hypothyroidism in Dogs?

Source: VCA Hospitals

Hypothyroidism is a condition in which the thyroid gland (a small gland with two lobes that sit around the trachea in the throat) is underactive in the dog's body. The thyroid gland normally produces thyroxine (T4) and triiodothyronine (T3), which are hormones that help regulate the body's metabolism. If the dog suffers from hypothyroidism these thyroid hormones are reduced or absent, which leads to problems with the skin, coat, energy levels, heat regulation, and immune system.

What causes Hypothyroidism in Dogs?

Hypothyroidism is caused by disease or destruction of the tissue in the thyroid gland. The two most common processes that cause gland destruction are inflammatory and degenerative, as outlined below. These two causes make up approximately 95% of cases. Tumours of the thyroid gland are a rarer cause and may account for up to 5% of cases.
- 1. Inflammatory destruction - lymphocytic thyroiditis. This is the most common cause and is thought to be immune-mediated. In this type of disease, the immune system attacks its own thyroid gland.
- 2. Degeneration - idiopathic thyroid gland atrophy. This type of Hypothyroidism occurs when normal thyroid tissue is replaced by fat tissue. This root cause of this condition is poorly understood.
- 3. Tumours of the thyroid gland. Thyroid tumours are rare but can cause hypothyroidism in up to 5% of dogs.

Dog breeds that are prone to Hypothyroidism

Hypothyroidism usually occurs in middle-aged dogs (aged 4-10) of medium to large sized dog breeds. Desexed dogs also have a higher risk. Particular breeds that are prone to developing hypothyroidism include:
• Retrievers including Golden Retrievers and Labradors
• Dobermanns
• Dachshunds
• Boxers
• Cocker Spaniels
• Miniature Schnauzer
• Irish Setters

Signs and Symptoms of Hypothyroidism in Dogs

Puffiness of the face forming the classic 'tragic face' of hypothyroidism. Photo by Dr. Carol Foil, sourced from VIN Veterinary Partner.

Hypothyroidism usually occurs in middle aged and senior dogs. Symptoms typically appear gradually over an extended period of time.

Clinical signs of Hypothyroidism include:
  • Weight gain, often without an increase in appetite
  • Puffy skin, known as the classic 'tragic' face
  • Brittle or thinning fur, particularly over the torso, abdomen and tail
  • Reduced energy, lethargy and listlessness
  • Inability to stay warm - owners often notice their dog shivers or seeks heat more than they used to
  • Chronic skin and ear infections
  • Increased pigmentation of the skin
  • Inability to grow hair back after shaving (shaving alopecia)

There are other less common, signs of hypothyroidism that occur occsionally. These include reproductive problems, nervous systems abnormalities such as nerve pain or dragging the hind legs, eye issues such as dry eye, and thickening of the facial skin which creates a droopy look.

Diagnosis of Hypothyroidism in dogs

How to know if your dog has Hypothyroidism

Diagnosis of Hypothyroidism requires a veterinary examination and blood tests. Your vet will need to complete a full physical examination, and rule out any skin infections with a skin scrape and cytology test.

Blood Tests for Hypothyroidism

Your vet will likely run the following tests:
- Baseline bloodwork (CBC / biochemistry)
- Urinalysis
- Total thyroxine level - also known as Total T4 or TT4. This test measures your dog's main thyroid hormone level. If it is low, this can be suggestive of a diagnosis - however total thyroid hormone can also be low from other disease processes that depress the immune system.
- Free T4 / TSH (thyroid stimulating hormone) levels. A full thyroid panel which measures TSH and free T4 is usually done after a low TT4 level was observed, as it is a more accurate indicator for hypothyroidism.

Treatment of Hypothyroidism in dogs

Photo credit: Hal Gatewood from unsplash

While hypothyroidism cannot be cured, the good news is that it can be easily treated with an oral medication. However, your dog will need to be treated with the oral hormone replacement for life.

Medication for Hypothyroidism in Dogs

The standard treatment for hypothyroidism in dogs is daily oral administration of levothyroxine. This drug is a synthetic version of thyroid hormone. Giving thyroid hormone daily helps replace the circulatory thyroid hormone concentrations and reverses the disease.

Ongoing care with regular vet check ups will be necessary to monitor your dog's progress and response to medication.

Home Care for a Dog with Hypothyroidism

In addition to giving your dog their medication daily, you will need to monitor your dog's skin and body weight to detect any changes. If the clinical signs disappear and your dog gets their appetite back, this is a good sign and means the medication is working. It's also important to feed your dog an appropriate food and limit treats and table scraps - read more about this below.

Recommended Diet for Dogs with Hypothyroidism

Do hypothyroid dogs need a special diet?

Unlike other conditions such as Kidney disease or Diabetes, a strict Prescription Diet is not required for Hypothyroidism. Most high quality adult diets - particularly those formulated for skin care - will meet the above criteria and keep your hypothyroid dog nourished and healthy.

Many dogs with hypothyroidism benefit from a skin care diet to help with any concurrent skin problems. Your vet may recommend a specific diet

As your dog begins to get their appetite and metabolism back with treatment, they may beg for treats and tidbits more. It is important not to give into the temptation to over treat them - and therefore limit treats, table scraps, and snacks, particularly those that are high in fat, salt, or sugar. Stick instead to healthy treats such as regular kibble, carrots, apples, or strawberries.

Top Skin Care Diets for a Dog with Hypothyroidism

1. Diamond Care Sensitive Skin

Diamond Care's Sensitive Skin Dry Dog Food is specially formulated with high-quality natural ingrediets, probiotics, and a grain-free formula with hydrolysed salmon as the single protein source. It is full of Omega-6 and Omega-3 fatty acids thanks to the salmon, flaxseed, and two separate oils, and completely grain free.

Major callouts: single protein, contains 5 beneficial bacteria strains as probiotics, grain and gluten free, and is one of the only foods on the market to use hydrolysed salmon instead of poultry.

Ingredients: Peas, pea flour, hydrolysed salmon, sunflower oil, flaxseed, natural salmon flavour, tomato pomace, salmon oil, dicalcium phosphate, calcium carbonate, DL-Methionine, choline chloride, taurine, dried Lactobacillus plantarum fermentation product, dried Bacillus subtilis fermentation product, dried Lactobacillus acidophilus fermentation product, dried Enterococcus faecium fermentation product, dried Bifidobacterium animalis fermentation product, vitamins and minerals.

Shop Diamond Care Sensitive Skin

Diamond Care Sensitive Skin

2. Royal Canin Dermacomfort

Available in small, medium, and large breed varieties, this dry food is specifically formulated to soothe irritation and promote skin health in dogs prone to sensitive skin.

Major callouts: the inclusion of Omega 3 & 6 fatty acids for healthy skin, and a low allergen formula.

Ingredients: Rice, wheat gluten, wheat, animal fats, maize gluten, husked oats, maize, minerals, hydrolysed poultry liver, soya oil, beet pulp, fish oil (source of EPA and DHA), flax seeds (source of omega 3), fructo-oligo-saccharides, borage oil (source of gamma-linolenic acid), marigold extract (source of lutein)

Shop Royal Canin Dermacomfort

Royal Canin Dermacomfort

3. Hill's Sensitive Stomach & Skin

Available in mini, small, medium, and large breed varieties, this dry food is formulated specifically for dogs with skin or digestive sensitivities, so may be ideal if your hypothyroid dog suffers from tummy troubles, too. It contains a gentle fibre blend to promote optimal nutrient absorption, easy digestion and healthy bowel function.
Major callouts: highly digestible, lean protein, antioxidants including Vit C and E.

Ingredients: Chicken, Chicken Meal, Yellow Peas, Cracked Pearled Barley, Brown Rice, Brewers Rice, Whole Grain Sorghum, Egg Product, Chicken Fat, Soybean Oil, Dried Beet Pulp, Chicken Liver Flavor, Lactic Acid, Flaxseed, Pork Liver Flavour, Potassium Chloride, Iodized Salt, vitamins & minerals

Shop Hills Sensitive Stomach & Skin

Hills Sensitive Stomach & Skin

4. Savourlife Sensitive Grain & Poultry Free with Ocean Fish

This Australian-made dry food is designed for dogs with sensitive skin and intolerances towards poultry.
Major callouts: grain and poultry free, uses mackerel meal as a primary protein and source of natural fish oil, and contains prebiotics, probiotics and superfoods including broccoli, blueberries and kelp.

Ingredients: Mackerel Meal, Tapioca, Field Peas, Chickpeas, Canola Oil, Vegetable Broth, Alfalfa, Vitamins & Minerals & Amino Acids, Fish Oil, Flaxseed, Sea Salt, Yucca Schidigera Extract, Chicory Root (Natural Prebiotic), Glucosamine, Tomato, Sweet Potato, Kelp, Carrot, Broccoli, Blueberries, Natural Antioxidants (including Rosemary Extract and Green Tea).

Shop Savourlife Sensitive with Ocean Fish


Supplements for Hypothyroid Dogs?

Supplements are generally not required if you are providing your dog with a balanced adult diet from a vet-recommended brand (like one of the diets recommended above!). However, hypothyroidism can create dry skin and dull fur, which can benefit from a number of nutrients supplemented, including:

1. Fish oil / omega fatty acids can help improve dull fur or inflamed skin, and strengthen the skin barrier.

2. Vitamins A, C and E can also help strengthen the skin barrier and promote a stronger immune system.

3. Zinc has antiinflammatory effects - particularly on collagen production, fatty acid metabolism and wound healing.

Top Supplements for Dogs with Hypothyroidism

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