The Most Common Endocrine Diseases in Dogs and Cats – Part 1

From Cushing’s to hypothyroidism, a variety of diseases can affect your dog or cat’s endocrine system. This two-part article looks at the most common endocrine diseases affecting our animal companions.

Your dog or cat’s endocrine system is made up of glands that secrete hormones to affect her body in various ways. The glands of the endocrine system regulate a range of functions, including metabolism, hair growth, muscle strength, digestion, and reproduction. Like other systems of the body, your dog or cat’s endocrine system can develop various disorders, the most common of which include diabetes mellitus, hypothyroidism, hyperthyroidism, Cushing’s disease, and Addison’s disease. This two-part article takes a closer look at these endocrine disorders, and how they can be treated using an alternative approach. Let’s start with hypothyroidism, hyperthyroidism, and Cushing’s disease.

FAST FACT: Most of these diseases have symptoms that overlap. One of the earliest and most common symptoms is increased thirst.


Hypothyroid disease, or an underactive thyroid gland, is the most common hormone imbalance in dogs, but is extremely rare in cats. The thyroid gland is responsible for metabolism; when it doesn’t function properly, the body slows down, leading to lethargy and obesity. The cycle of hair growth and shedding is interrupted, and many dogs develop bald patches, particularly along the flanks. The hair will become dry and brittle and lack shine. Skin and ear infections are commonplace. Some dogs become anxious, depressed, aggressive, or develop seizures.

Primary hypothyroidism is caused by autoimmune thyroiditis, in which the immune system attacks the thyroid gland. Decreased production of thyroid hormones may also occur with age. Large breeds seem to be affected more often, with Dobermans, Labradors, and greyhounds leading the list.


  • Supplemental synthetic thyroid hormone (levothyroxine) — given twice daily, starting at 0.05 to 0.1 mg per 10 to 15 pounds body weight. It should be given one hour prior to or two hours after feeding (not with meals) to ensure proper absorption. Some supplements contain ground thyroid gland, which can add thyroid hormone without synthetic supplementation.
  • Healthy, minimally-processed, species-appropriate whole food diet — more protein, less carbs.
  • Decreased (or stopped) vaccines.
  • Vitamin D — found in cod liver oil, sardines, eggs, kefir, and beef liver, to support the immune system.
  • Kelp — a source of iodine, which is required for thyroid function; 1/4 teaspoon for small dogs, ½ teaspoon for medium dogs, 1 teaspoon for large dogs.
  • Omega-3 fatty acids — 20 to 30 mg per pound of body weight daily of EPA and DHA combined.
  • Herbal thyroid supplements containing licorice root, rehmannia, and ashwagandha.
  • Vitamin A — 50 to 100 IU per pound of body weight daily).
  • Ester-C — 100 to 500 mg daily, dosed to bowel tolerance – use lower dose if diarrhea develops).
  • Vitamin E — 400 to 1,000 IU per day to support endocrine function.
  • Thyroid hormone levels should be closely monitored, as over or under-supplementation can have dire consequences. Be sure to work closely with your veterinarian.

FAST FACT: Hypothyroidism, diabetes, and Cushing’s disease commonly occur together.


Hyperthyroidism, which refers to an overactive thyroid gland, is a disease of cats. When seen in dogs, it is almost always related to a malignant functional thyroid tumor (but has also been seen in dogs fed diets containing thyroid glands). Cats develop benign adenomas of the thyroid gland; only 2% to 3% have malignant thyroid tumors.

Symptoms may include hyperactivity, increased thirst and urination, vomiting, diarrhea, increased appetite with weight loss, excessive vocalization, racing heart rate, high blood pressure, and possibly a palpably enlarged thyroid gland.

FAST FACT: The average age of hyperthyroid cats at diagnosis is eight to 13 years.


  • High quality, high moisture diet — frozen raw, home-cooked, or rehydrated freeze-dried raw.
  • Yin tonifying (cooling) meats — e.g. rabbit, duck, grass-fed beef, liver, and clams.
  • Milk thistle (5 to 10 mg per pound twice daily) and/or SAM-e (90 mg daily) — liver enzymes are commonly elevated with this disease so liver support is essential.
  • Foods high in vitamin A — e.g. carrots, kale, spinach, and barley grass; add in small amounts if the cat will eat them; they can be cooked and minced or fed raw.
  • L-carnitine — 250 to 500 mg twice daily for cardiac support; also found in high quantities in red meats.
  • Taurine — 250 to 500 mg two to three times daily for cardiac support; also found in high quantities in red meats, poultry, eggs, dairy products, and fish.
  • Herbs to balance thyroid function — bugleweed, which has been shown to decrease thyroid hormone output; and hawthorn, which can help lower blood pressure and decrease the work the heart is doing.
  • Acupuncture — can help balance the immune system and lower blood pressure, as well as support the kidneys and liver.
  • No more vaccines.


Hyperadrenocorticism, or Cushing’s disease, occurs in dogs but is rarely seen in cats. Symptoms include increased thirst and urination, excessive panting, hair loss, muscle weakness, pot belly, liver enlargement, and chronic skin or urinary tract infections. Hormones released from the adrenal gland include cortisol as well as estrogen, progesterone, and testosterone. This disease can be caused by a tumor in the adrenal gland (may be more common in large breeds), a tumor in the pituitary gland (may be more common in small breeds), or by over-administration of steroids. If testing reveals primary adrenal production, an abdominal ultrasound is recommended to rule out an adrenal gland tumor; these can be highly malignant and aggressive and difficult to remove surgically.

FAST FACT: Pituitary gland tumors are much more common, occurring in about 85% of dogs with Cushing’s. These benign, slow-growing tumors usually do not spread to other areas of the body.

Dogs with Cushing’s disease commonly have high blood pressure, which should be monitored and treated. They may also have elevated calcium levels which can lead to the production of bladder and kidney stones. Pancreatitis is a common complication.


  • Melatonin — 3 mg twice daily for small dogs, and up to 6 mg twice daily for large dogs; decrease dose if animal is too sleepy or lethargic.
  • Flax seed lignans or HMR lignans — 20 to 40 mg once daily.
  • Glandular products — including ground adrenal, pancreas, and thymus glands.
  • Antioxidant vitamins — vitamin A (50 to 100 IU per pound of body weight daily); ester C (100 to 500 mg daily dosed to bowel tolerance – decrease dose if diarrhea develops), and E (400 to 1,000 IU per day).
  • CoQ10 — 100 to 400 mg daily as an antioxidant.
  • Chinese herbal formulas — Si Maio San, Ophiopogon, Liu Wei Di Wang, or Rehmannia at 0.5 gm per 10 to 20 pounds body weight twice daily; your holistic veterinarian will choose the herbal formula that best suits your animal.
  • Acupuncture — lowers blood pressure and increases energy and muscle strength.
  • Hawthorn berry — lowers blood pressure; feed 1 teaspoon of ground berry per one pound of food or ½ teaspoon of hawthorn tincture daily.
  • Milk thistle (5 to 10 mg per pound of body weight twice daily) and/or SAMe (90 mg for small dogs, 225 mg for medium dogs, and 400 mg for large dogs) – liver function should always be supported.
  • Healthy, high quality diet — good quality protein sources, minimal or no carbohydrates, plenty of leafy green vegetables, lower calcium levels to prevent formation of bladder stones.
  • No more vaccines.
  • Minimal stress.


The causes of hyperthyroidism in cats are still not completely known. PBDE (polybrominated diphenyl ether), a chemical flame retardant used in many industries; and BPA (bisphenol-A), used to coat the inside of pet food cans, have both been incriminated. However, BPA may not be the cause of the problem. PBDE is found in ocean fish due to pollution, so the association may actually be with the chemicals in the fish, not the can. The amount of iodine in cat foods (too much or too little) may also play a role, as well as the addition of soy, which can disrupt thyroid function.


If you suspect your dog or cat might have one of the endocrine disorders discussed in this article, it’s vital to take her to a holistic or integrative veterinarian for a proper diagnosis, and to follow his or her guidance when it comes to treatment. Do not give your dog or cat any new supplement or remedy without first discussing it with your vet.



Judy Morgan, DVM, CVA, CVCP, CVFT

Veterinarian Dr. Judy Morgan is certified in acupuncture, food therapy and chiropractic care for dogs and cats. A sought-after speaker and blogger, she integrates Eastern and Western medicine at her two practices in New Jersey ( She has authored two books — From Needles to Natural: Learning Holistic Pet Healing and What\’s For Dinner Dexter? Cooking For Your Dog Using Chinese Medicine Theory.

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