Hypothyroidism in dogs: symptoms and treatment

Some breeds seem to be genetically predisposed to hypothyroidism
The most common hormonal or endocrine disorder seen in dogs today is hypothyroidism, otherwise known as an underactive thyroid gland. This condition is most commonly seen in middle-aged and older dogs, although some cases have been reported in younger animals as well. Some breeds seem to be genetically predisposed such as standard Poodles, Schnauzers, and Retrievers, but it’s also common in mixed breeds and other breeds of dogs as well.

While in many cases we don’t know the causes of an underactive thyroid gland and thyroid atrophy in dogs, in other cases there is an autoimmune destruction of the thyroid gland by the dog’s own immune system. In fact, toxic environmental exposure, nutritional factors, and even vaccinations have sometimes been incriminated as contributing to autoimmune destruction of a dog’s thyroid gland, known as autoimmune thyroiditis.

Symptoms of a low thyroid can vary tremendously. Some of the more common ones include weight gain/low energy without an increase in appetite, cold intolerance, chronic ear and/or skin infections along with coat changes including dull, dry or oily coats, hair loss often symmetrically along the back, as well as thin skin. Some pets may develop neurologic complications including behavioral changes and aggression, as well as problems with the facial nerves including a Bell’s palsy-like syndrome resulting in a facial droop.

Other pets may manifest with chronic regurgitation or vomiting problems, sometimes diagnosed as megaesophagus, where chronic regurgitation can become a frustrating and health threatening problem. And while one can see that there are many possible signs of a low thyroid in this common endocrine/hormonal disorder of dogs, hypothyroidism is also equally as overdiagnosed by many veterinarians. Chronic illness anywhere in the body, as well as many drugs such as Phenobarbital, can actually lower measured resting thyroid hormone levels such as T4, that can often erroneously lead veterinarians to misdiagnose this condition.

Other chronic illnesses and certain drugs can lower T4 levels dramatically often resulting in what is known as euthyroid sick syndrome, meaning that there is not a low thyroid condition, but other disorder or medication causing the low blood levels, often resulting in a misdiagnosis by a veterinarian. Therefore it’s important whenever trying to diagnose a pet with this disease, that a full blood thyroid panel be done, including measurement of blood T4, Free T4 by equilibrium dialysis, as well as TSH levels and thyroid and thyroglobulin autoantibodies, to most completely assess thyroid function in dogs. Treatment is very inexpensive using either synthetic L-thyroxine, or in those more holistically inclined through use of armour thyroid supplementation.  This is also a disease where I feel nutritional factors play a role in causation as well as treatment.

Insuring an optimal natural diet such as Azmira, Pet Guard or Wysong, or even a proper home made diet, can help prevent as well as help in treating affected dogs.  Nutritional supplements such as enzymes like Prozyme or NaturVet Enzymes & Probiotics added to meals, which increase trace mineral digestion and absorption such as iodine and selenium, can also help provide proper nourishment and support for the thyroid gland. Kelp powder and lecithin granules can also be important nutritional supplements to consider in affected dogs.

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18 Comments

  1. My male German Shepherd, approx. 12 -13 years old, weight 81 lbs., recently lost about 25lbs and developed a cyst like wound on his neck near his throat (wind pipe area). At first we thought he might have been bitten in confrontation with a shabby standard size Poodle, not quite sure but it looked like that was the case, so we treated it with antibiotics and kept it clean and disinfected with Peroxide, Dermoplast spray Bacitracin and kept it dressed and covered with gauze and ace bandage (changed twice a day). It became swollen like half an orange. We shaved the area and saw that it stayed swollen
    and appeared to have two spots that looked very sore. It still looked like the sores were an inch or so apart (possible bite
    marks) wound is still draining a lot but swelling has stayed about the same (maybe a little smaller). Now it seems like
    it may be infringing on his throat and he is drooling lots.
    Would like advice besides “See a Vet.” I realize he is old now for a Shepherd. Does it sound like possible Cancer?
    Or something else that is common to Senior Shepherds?

    • Dr. Michael Dym, VMD veterinarianMarch 10, 2011 at 12:38 am · Reply

      It does sound like either a severe inflammatory/infectious process which could be from a foreign body or cyst. The other possibility is cancer. Unfortunately only way to diagnose and treat is to have surgical biopsy or exploration of area to find out. And that does need a vet visit.

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  4. My 10 year old terrier mix was diagnosed with hypothyroidism. He has been taking Levothyroxine and showing some improvement. However, he recently and rapidly became blind. Now it seems his hearing is going too. Could the blindness be attributed to the Levothyroxine?

  5. Thank you for your reply Dr. Dym.
    My dog is receiving care for his condition. I asked the question mainly for a second opinion. As I have done some research on Levothyroxine and found a human study that found a small percentage of people did report blindness as a side effect of this medication. My vet did agree with your opinion. Thank you again.

  6. our one year old malamute/timber-wolf, has just recently swollen up in his lower jaw area. He is showing signs and symptons of hypothyroidism. Could this be at such an early age?

    • Dr. Michael Dym, VMD veterinarianApril 10, 2013 at 9:03 pm · Reply

      Hypothyroidism occasionally occurs in young dogs at one year of age. I would consider other illnesses causing swelling in lower jaw area. HAve vet evaluation to help sort out.

  7. My collie has been diagnosed with hypothyroidism after being on Rimadyl long term for recovery of a cruciate ligament. Could this have caused it?

    • Dr. Michael Dym, VMD veterinarianAugust 28, 2013 at 12:11 am · Reply

      Dont think rimadyl involved but I would make sure FULL thyroid panel done on dog to make sure disease accurately diagnosed, as chronic illness like cruciate ligament and even drugs can sometimes falsely lower T4 levels.

  8. My 11 year old chocolate lab was diagnosed with hypothyroidism 3 years ago. Up till recently the meds were working but now he takes 900mcg twice a day and s-adenosyl-225 tabs 1 day. And his t4 levels are very low, and now he’s losing hair on his belly and back and sides. Could he just not be responding to the meds anymore is that possible? He’s behaviour is no different than usually still very happy and active.

    • Dr. Michael Dym, VMD veterinarianSeptember 15, 2013 at 11:43 pm · Reply

      Could be that he has another illness causing the lower T4 levels and continued hair loss. I would ask vet about repeating complete CBC/Chem and urine lab work to look for other diseases/illnesses. If this workup non remarkable, then consider asking your vet about writing script for more natural thyroid supplement such as Armour thyroid

  9. I \inherited\ a 10-yr-old PBGV who came with medication for his hypothyroidism. As he lost weight and got back to normal I halved the dose. He has been fine – Recently someone told me he would start losing his fur. I put him back on a full dose and now he has an insatiable thirst – could it be the dose change? Full dose is o.6mg of Soloxine tabs.

    • Dr. Michael Dym, VMD veterinarianDecember 2, 2013 at 12:36 am · Reply

      Dose change may be related, but best to have thyroid levels checked 4-6 hrs after AM pill to get accurate blood levels.

  10. Our PBGV was diagnosed with hypothyroidism at 5 years of age. I was suspicious that her condition was initiated after her distemper booster, since it was within a month after that she began to gain weight, lose her healthy coat of hair and feel much less energetic. The change was so sudden. She even developed \cherry eye\. After she was put on thyroid supplement, she began to improve. Now, however, our second PBGV at age 2 has suddenly developed hypothyroidism and this within one month of her rabies shot. Both dogs went from feeling very good to very bad within a short time of being vaccinated. My suspicion is that a component of the vaccine in shots initiates hormonal disruptions that initiate the hypothyroidism. I understand the shots contain many ingredients and among those are mercury and aluminum. Could some breeds have a super sensitivity to these components? The breeder is very careful to test her dogs for thyroid problems as puppies. I think we need to ask more questions. I won’t take a vaccine that includes mercury…

    • Dr. Michael Dym, VMD veterinarianJune 27, 2014 at 11:09 pm · Reply

      Thanks Dorothy for your excellent points. Believe me this issue has been looked at . My good colleague and friend, Jean Dodds, DVM has written and spoken extensively about the link between vaccination and thyroid disease in some breeds, due to autoimmune reaction potentially affecting this gland. You can access her work on line. Many years ago, it was shown that in a certain percentage of rabies vaccinated dogs, autoantibodies against their own thyroid gland does occur. Sometimes mercury and aluminum can play role, but in others these not involved. Support less vaccination as ONE distemper/parvo vaccination elecits years to life time immunity, and new work going on that will hopefully support extending rabies laws http://www.rabieschallengefund.org. Also see my website http://www.doctordym.com for more info. Try and work with a holistic vet, even if one over phone, as vets like myself have clients around country.

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