Hypothyroidism in Dogs: Causes, Symptoms And Possible Treatment

Hypothyroidism in Dogs
Wyatt Robinson
Written by Wyatt Robinson

It is amazing just how much animals are like humans and can be affected by some small organ in their bodies. Take for example the thyroid gland. Like in humans, this simple little organ is very important in a dog and can cause all sorts of issues when anything goes wrong with it. This small gland is where the hormone thyroxine is produced. Thyroxine controls the rate of metabolism or the rate of how the body burns calories. Some things can upset the functioning of the thyroid gland, causing it to produce too little thyroxine.

When enough thyroxine is not produced this is called hypothyroidism. Hypothyroidism in dogs is a common problem.

How the thyroid functions

The thyroid gland is a small elongated gland that is situated in the base of the neck just below the voice box of the dog. In humans it has the shape of a butterfly and an impression can be seen right at the front of the neck. In the dog the gland has two lobes, one situated on each side of the wind pipe.

The thyroid tissues are made up of microscopic sac-like cells from which two hormones are secreted. These are thyroxine – T4, and tri-iodothronine – T3 hormones. These hormones need iodine to be produced. Another set of cells in the thyroid produces a hormone called calcitonin that regulates the amount of calcium in the blood.

Thyroid gland

Thyroid hormones are produced with the stimulation of thyroid-stimulating hormones or TSH that come from the pituitary gland. Both thyroid hormones are needed in the dog for the proper functioning of the body. There can be too little production of hormone however, and this is hypothyroidism.

Understand that the thyroids can also operate at the other end of the scale where they become over-active, giving rise to the condition of hyperthyroidism. When regular amounts of thyroid hormones are produced, the metabolic rate of the dog’s body increases and the cells work harder. More energy is therefore produced and proper body function takes place, such as:

  • Body temperature rises
  • Heartbeat is stronger and therefore the pulse rate is faster.
  • Food is broken down more quickly and used up by the body faster.
  • Growth takes place and puppies’ brains mature
  • The nervous system is activated allowing dogs to be more attentive and body reflexes are quicker.

Causes of hypothyroidism in dogs

  • Immune system problem — In some cases hypothyroidism is caused by the dog’s own immune system attacking the tissues of the thyroid gland. When this happens the condition is called auto-immune thyroiditis and in this case the sacs that produce thyroxine are not able to function as they should, therefore producing less of the hormone. At (2015) Doctors Foster and Smith reported that more than 95% of all cases of hypothyroidism occur as a result of the immune system’s effects on the thyroid.
  • Shrinking of the thyroids — In the other cases, dogs simply stop producing less and less thyroxine in their thyroids. This can be due to the shrinking of the thyroid gland tissues. The condition eventually comes to the point where the amount of the hormone becomes insufficient to support what the body requires.
  • Genetics — In few cases, it is a matter of genetics. The problem is carried down the line of generations of dogs. Very often some breeds of dogs carry some disfiguring condition that makes them susceptible later in life. If the grandmother and the mother developed the disease, it means that the daughter or son will get it too. This is why Hines suggests that dogs with hypothyroidism should not be bred.
  • Effects of medication – Some forms of medication can also affect the production of thyroxine in the glands. Dogs that take steroids for some other problems are known to develop lower thyroxine issues.

Dogs that are most at risk

All dogs have the propensity to develop hypothyroidism and it has been seen in all breeds. However, dogs in the middle to older age groups – between 4 and 10 years, are diagnosed many times more than younger ones.  Medium to large breeds are highly susceptible. There are also several breeds that vets tend to see more often with the disease in their practice. Golden retrievers, Doberman pinchers, Labradors, Dachshunds, Irish setters, Boxers, Cocker spaniels and Greyhounds are seen to have higher incidences of hypothyroid problems than other breeds.

Dog at risk

Smaller dogs and toy breeds are rarely treated for the disease. An unexplained but very real situation is that the disease has been seen in both neutered and spayed dogs as against those that are intact. The experts are still seeking to determine the reason behind this. One of the theories is that the removal of reproductive hormones can interfere with the endocrine system making dogs vulnerable to issues such as hypothyroidism.

Exploring symptoms of hypothyroidism in dogs

Hair and skin disorders — There is a range of symptoms that is associated with the disease. Most hypothyroid dogs usually turn up with some kind of skin disorder. Brooks (2015) points to a study of 162 dogs with the disease which found that 88% of the animals had skin disorders. One of the first signs you will notice is hair loss and in that study, 40% had that problem. There is usually balding on the trunk and the back of the hind legs.

There is also the condition where your dog’s tail may become as hairless as a rat’s. This hair loss will pique your interest since it is not that baldness that occurs with itchiness as happens in a flea infection or in the case of allergies. Therefore you must take note of the difference. Coupled with hair loss, black patches will appear especially in the groin area. You may notice also that the skin around the face and head will become thickened.

Dog obese

Obesity — You will also notice your dog putting on weight even though he maintains the same amount of food he eats. This is followed by sluggishness, and his heart rate is really reduced. The Brook mentioned study found that 49% of the dogs were obese and 48% were lethargic in their movement.

Infections – A common sign also is infection of the toenails and ears. The nails will break off easily and make walking a bit difficult.

Reproductive problems — Infertility in both male and female is a very real problem. Male dogs will experience low sperm count and fail to sire puppies. Females experience erratic heat cycles and therefore are not able to get pregnant, may miscarry, or have small litters.

Other conditions — There is also a litany of other behaviors that are associated with dog’s hypothyroidism. Hypothyroid dogs become intolerant of the cold. In fewer cases, dogs develop seizures, heart and blood vessel problems.  The animal is not as alert as before; he lacks focus and may not remember his training.  Constipation, muscle weakness, joint pain, and anemia are some other problems they may have.

Diagnosing the disease

Diagnosing hypothyroidism can be complicated. However, a blood test is usually done to confirm levels of T-4 and T-3 substances in the dog’s body. The level of thyroid-stimulating hormone (TSH) coming from the pituitary gland is also checked. Where there are low T-4 levels and high TSH levels, this is a positive confirmation of hypothyroidism. Normal T-4 levels range from 1.0 – 4.0 micrograms/deciliter. A level 1.0 microgram is borderline and anything lower than this is an indicator of the disease.

Diagnosing hypothyroidism can be backed up with other tests especially if it is suspected that there is the presence of a tumor. An ultrasound of the neck area, radio-active iodine scans, fine needle aspiration and biopsy are part of this option to check on the cause of lower thyroxine. Tests also must be done with the understanding that other health issues in your pet can indicate low thyroid hormone substances.

Thyroid disease

Also, medication that contains steroids can be the problem. One further suggestion to determine hypothyroid problems is that the dog is placed on a 30- day course of medication to see if the condition improves.

You should be mindful however that some breeds of dogs naturally do have lower thyroxine levels and therefore care must be taken when diagnosing for hypothyroidism in them. Sight Hounds such as greyhounds, Italian greyhounds, Whippets and Salukis are in this category (Hines).

Treatment and care of your pet

  • Treatment with medication — When your dog has been diagnosed with hypothyroidism the animal would probably have been long affected by the disease prior to this and would have suffered irreparable damage. Now he must have thyroxine replaced and this most often can only be done by using synthetic thyroid hormones. Levothyroxine or L-Thyroxine is the drug that is normally given to dogs. The drug is specific to each dog however, depending on the causes of the thyroid problem.
  • Retesting — An aspect of the treatment is monitoring how well the dog responds to the medication. The vet will also want to be assured that the dog is adequately treated and that the dosage of the medication is not too high or low. Too high a dosage will send the thyroxine levels skyrocketing and eventually the dog will start consuming excessive amounts of water, weight loss will set in and he becomes irritable. Periodic blood tests will need to be done to determine this.
  • Monitoring of treatment – You may expect to have your dog do a blood test annually as the doctor seeks to check the status of T-4 hormone in the body. In such a test, blood is drawn from the dog just before the time he takes his first tablet and when the thyroxine is lowest. The test is also done 4 — 6 hours after taking his last medication or when the thyroxine level is highest.
    Monitoring of TSH Levels will also give an indication of how well the medication is working. It will not give an indication of how high the dosage of thyroxine is, but rather how low it is. The more TSH is being produced, the less thyroxine is suggested. It is an indication that the pituitary gland is working harder to produce more TSH to stimulate the thyroid gland into making thyroxine. This means that an increased dosage of thyroxine will be required for normal body functioning.
  • Stimulation of hormone tissues — Doctor Becker at recommends the stimulation of the thyroid tissues if they are not affected by auto-immune problems. Tissues that shrink and or stopped working can be stimulated to get them working again (, 2015). Here a more natural form of replacement is suggested using desiccated thyroids or thyroid extracts.In this approach, porcine or bovine thyroid glands in dried and powdered forms are administered to the dog.
    The product is sometimes referred to as “natural thyroid”, “natural thyroid hormones”, “pork thyroids’ and also commercial brands such as “Armour Thyroid” and “Westhroid”.
  • Prevention is better than the cure — Dogs can be properly monitored for better health results. Owners can be more watchful for health issues before they grow into ones that are going to affect the quality of the animals’ lives later. As the dog owner, seek to have tests (blood) done to check the conditions of the vital organs of your pet’s body.
    According to Dr. Becker (Mercola, 2015), no blood value is ever healthy enough and opportunities should be taken to make it better. Consult with your veterinarian to start the process of fixing any low thyroid levels before they generate into difficult problems.
  • Natural remedies – Homeopathic remedies are indicated as natural remedies that can help sick dogs lead better lives. For examples, kelp and seaweed are high in iodine and therefore will help to stimulate the cells of the thyroid. The thyroid produces hormones with the help of iodine. Some dogs will also benefit from Vitamin A and C bearing foods that exist in large amounts.
    Therefore, you can consider feeding your dog with fish that has plenty cod liver oil or supplements of the food. Vitamin B is also helpful and foods like alfalfa, parsley, fennel and oats are highly recommended. With such sluggish immune system, your dog will benefit from Omega – 3 fatty acids. In speaking of food, dogs will benefit from a change in their diet that probably is making them fat. Dog owners should review their pets’ diet and seek to remove those items that will make them gain too much weight. Seek to feed your pet healthier foods to maintain a steady balance in weight.
  • Exercise – This is the time when your dog probably may not want to exercise. He may find just getting up to walk a challenge. You will have to find some way to encourage exercise as this will help him lose and keep off some of the weight. Take short walks with him. Rest if he needs to. Very soon he will start looking forward to even these brief moments.
  • Be understanding – Hypothyroidism can suddenly creep upon you and your pet and you are thrown in the whirlpool of what to do. All of a sudden your dog is not spritely as before, he is gaining weight and becoming “lazy”, and he lacks interest. A visit to the vet and he has to be taking medication. This all calls for you to be understanding, patient and caring.
    A dog that is not treated for hypothyroidism will experience a reduced quality of life. Irritability, diarrhea, weight loss and other problems will beset him. Luckily, your dog can live a normal life with medication. He will however have to take the medication for the rest of his life. Importantly, ensure that he gets his medication and that he is nursed back on the path to good health. This way both your quality of life will be improved.
  • Work with your vet – You will find a friend in your vet to help walk you through your dog’s illness with hypothyroidism. Lean on the experts’ advice, they know best. However, get to know more about the disease so that you can make your own contribution. Keep appointments, for this is how your vet will monitor your pet’s condition and also the dosage of the medication given.

In conclusion

Hypothyroidism is a condition that causes the reduction of thyroid hormones in dogs and this can lead to real serious problems that prevent your dog from doing as well as he used to. This can be a drastic change as the dog is lethargic and seem not to be able to maintain its normal weight.

Dog thyroid

Several factors exist that cause problems in the thyroid, one or more of them may be at work in your dog. The good news is that hypothyroidism is not usually a life threatening illness, but need to be managed for best results. It is recommended that the dog’s diet be managed, the pet is encouraged to exercise and owners be understanding. This way, everyone gets the best results.

About the author
Wyatt Robinson
Wyatt Robinson

Wyatt Robinson had a great 25-years career as a veterinarian in United Kingdom. He used to be a member of British Veterinary Association and worked in 3 pet hospitals in London and Manchester. He is shining when he sees his pets healthy and full of energy and it is his duty to help other dog owners to keep their best friends full of life.