Hypothyroidism in dogs is one of the most over diagnosed diseases in dogs, mostly because it has symptoms that are common in other hormonal imbalance disorders like Cushing’s, Addison’s, or diabetes mellitus.
The simple definition of canine hypothyroidism is that your dog’s body has lower levels of thyroid hormones than your dog needs to thrive. When a dog has hypothyroidism, his whole body just slows down.
What Causes Hypothyroidism in Dogs?
Your dog’s thyroid is a little butterfly-shaped gland that is found at the base of her neck. The thyroid is right beside your dog’s windpipe, near her voice box.
When a dog has hypothyroidism, his thyroid is the guilty party causing the trouble. Its job is to regulate your dog’s thyroid hormones. These hormones, in turn, affect your dog’s energy levels, hair growth and health, body temperature and weight. When the thyroid is not producing enough hormones, your dog suffers from hypothyroidism.
About 90-95% of dogs with hypothyroidism have an autoimmune condition that has actually destroyed their thyroids. Others have a tumor on the pituitary gland.
While those are the main causes, there are a few more:
- Unknown etiology – this is medicalese for “nobody knows why”.
- Congenital disease – A dog can be born with hypothyroidism. Dogs born with thyroid deficiency or who develop a deficiency as puppies, end up with dwarfism and they are mentally slow.
- Iodine deficiency
Which Dog Breeds are Most Affected?
Hypothyroidism in dogs usually affects mid to large size dogs like the Weimaraner and is seen less often in small toy and miniature breeds.
Although hypothyroidism can be found in any breed, we see it most often in these breeds:
- Airedale Terrier
- Golden Retriever
- Doberman Pinscher
- Irish Setter
- Miniature Schnauzer
- Cocker Spaniel
Usually a dog is diagnosed when she is between 4 and 10 years old. The disease is found in both males and females equally. Interestingly, females who have been neutered, are more likely to have hypothyroidism than those that are not.
Hypothyroidism Symptoms in Dogs
Like any other dog hormone diseases, hypothyroidism has quite a few symptoms. However, the most common ones, seen in most dogs with this condition, are weight gain, lethargy or slowing down and sensitivity to cold.
Behavior and General Physical Symptoms
- Aggression – Dogs who are already prone to aggression, can be more irritable
- Weight gain – The most common medical cause for weight gain is hypothyroidism. Even though your dog has gained weight, he has a poor appetite.
- Inactivity – Your dog is not enthusiastic about playing or going for walks. Blood tests may show that your pet is anemic.
- Sensitivity to cold – Your dog may shiver when exposed to colder temperatures or he may seek to be where it is warm.
- Mental dullness – Your dog seems to have trouble understanding what you want her to do.
Female dogs who have not been spayed may miss their heat cycles, may have trouble conceiving, and if they do have a litter, the puppies might not survive.
Male dogs with hypothyroidism show no sexual interest, have small testicles, have a low sperm count, and are often infertile.
- Thinning of hair – You may notice that your dog is shedding more hair.
- Delayed regrowth of hair after grooming is another sign.
- Skin – gets thicker, especially on the forehead and face.
- You may see minor skin infections.
- Dry, dull coat
- Dry skin with dandruff or scaling
- Hyperpigmentation – dark spots that you didn’t notice before
Untreated or Advanced Cases of Hypothyroidism in Dogs
Of course if a hormone deficiency is untreated or ignored, your dog’s symptoms will continue to get worse. You may see:
- Vision loss or blindness
- Nerve disorders
- Joint inflammation
If your dog has been diagnosed with hypothyroidism, you will be interested in reading The Canine Thyroid Epidemic: Answers You Need for Your Dog, by W. Jean Dodds, DVM and Diana R. Laverdure.
What is the Treatment for Canine Hypothyroidism?
Hypothyroidism in dogs is one of the most under or over diagnosed diseases in dogs, based on your view point. This is mostly because it has symptoms that are common to other hormonal imbalance disorders like Cushing’s, Addison’s, or diabetes mellitus. These hormone disorders are often mistaken for each other.
If your dog is diagnosed with hypothyroidism, the vet will prescribe hormone therapy. Your dog will take a synthetic hormone, L-T4. This synthetic hormone replaces the thyroid hormones your dog lacks.
In most cases, you will see positive changes in your dog’s coat, weight and energy levels after 1-2 months of hormone replacement.
Whenever I can offer a natural treatment solution for your dog, I will do so. In this case, however, I have not found any natural treatments or herbs that will help correct canine hypothyroidism.
What if Your Dog doesn’t Improve?
If your dog still has all the symptoms of hyperthyroidism, even after 1-2 months of therapy, your vet will consider these possibilities:
- The dosage is not right yet. – Blood tests will help determine if this is the reason.
- You are not giving the meds, as instructed (missing doses, forgetting to give them).
- Your dog is excreting too much of the medicine or his body is not absorbing it well enough.
- Wrong diagnosis – So many hormone imbalance disorders look alike, it’s easy for a vet to think your dog has the wrong disease. Dog disorders caused by hormone imbalance tend to affect every system of your dog’s body. Thyroid problems in dogs are the most over-diagnosed condition in dogs.
Prognosis for Dogs with Dog Thyroid Disease
Fortunately hypothyroidism in dogs is a disease that we can control easily. When your dog takes replacement hormones, after a month or two, you will think you have a new dog.
Your dog’s symptoms will disappear, and, if you continue to monitor her progress and give her the meds, she will live a normal life with no residual problems.
The Opposite of Hypothyroidism is Hyperthyroidism
What is Hyperthyroidism in dogs?
The exact opposite of hypothyroidism in dogs is hyperthyroidism. If your dog has this, his metabolism speeds up and goes crazy.
This is really quite unusual in dogs, so your dog probably does not have it. However, a few dogs do end up with this condition.
There are really only two causes for hyperthyroidism. Your dog’s medication for hypothyroidism could be too strong, or your dog has carcinoma or thyroid cancer. The most common cause is cancer.
Hyperthyroidism Symptoms in Dogs
A dog’s faster metabolism drives the symptoms for this disease.
Signs You May See
- Weight loss
- Huge increase in appetite
- Extra thirsty
- Pees more often and larger amount
- More poop than usual
Symptoms Your Vet May Find
- Congestive heart failure
- Faster heart rate
- Shortness of breath
- Enlarged heart
- Heart murmur
How is Canine Hyperthyroidism Treated?
If a dog is diagnosed with hyperthyroidism caused by cancer, your vet may suggest surgery, chemotherapy or radiation treatments.
Even though these treatments are available, the prognosis for dogs with hyperthyroidism is poor to grave.