Hyperthyroidism has been linked to pet foods that include the thyroid glands of slaughtered animals. Because pet food consumers are not informed of what portions of slaughtered animals are used in pet food, knowing the symptoms of hyperthyroidism could be important to protect your pet’s health.
Recently I heard from a pet food consumer whose healthy dog started to have a dry, ragged coat and showed some aggressive tendencies towards other dogs. This pet owner sent Dr. Jean Dodds some blood for testing and the results showed the dog’s thyroid levels were nearly 4 times normal. Four times normal thyroid levels could have resulted in stroke or blindness or even death.
This dog had previously been fed a home prepared raw diet, but ten months prior to the finding of extremely high thyroid levels the owner changed the dog to a commercial raw beef diet. And it happened that this dog’s thyroid levels were checked just before the change to the commercial raw beef diet – at that time they were ‘low normal’.
Dr. Dodds suggested to the pet owner to remove the current pet food. The owner did, went back to the home prepared locally raised raw meat pet food as was used before, and in two months time this dog’s thyroid went back to normal.
In ten months time, this dog’s thyroid levels went from low normal to a dangerous 4 times normal. Two months after removing the suspect pet food, the dog’s thyroid levels were back to normal. Why?
We can safely assume it is diet related hyperthyroidism.
Hyperthyroid issues can be caused by a tumor on the thyroid gland, an error in medications, or it can be diet related. Diet related hyperthyroidism is linked to pet foods or treats containing the thyroid gland of slaughtered animals. The big problem for consumers is – we are not informed if the pet food/treat we purchase contains the thyroid gland of slaughtered animals.
The research available on this shows this is more of a concern for dogs than cats (but note the research is very limited – it is unknown if cats are at the same risk for diet related hyperthyroidism).
Dr. Karen Becker wrote on this issue in 2014 – quotes from her post…
In a 2012 study published in the Journal of Small Animal Practice,1 12 raw fed dogs were evaluated for elevated plasma thyroxine (thyroid hormone) levels. Six of the dogs had symptoms of hyperthyroidism, while six had no clinical signs. After a change in diet, 8 of the dogs’ thyroxine levels returned to normal and their symptoms resolved.
The study authors concluded that:
“Dietary hyperthyroidism can be seen in dogs on a raw meat diet or fed fresh or dried gullets. Increased plasma thyroxine concentration in a dog, either with or without signs of hyperthyroidism, should prompt the veterinarian to obtain a thorough dietary history.”
Dr. Mark E. Peterson – a veterinary endocrinology specialist – shared the following insights on dietary hyperthyroidism in dogs…
“In man, community-wide outbreaks of “hamburger thyrotoxicosis,” resulting from inadvertent consumption of ground beef contaminated with bovine thyroid gland, have been previously reported (3,4). These outbreaks resulted in the banning of “gullet trimming,” in which meat in the neck region of slaughtered animals is ground into hamburger. Because thyroid tissue is similar in color to muscle meat, it is possible for gullet trimmers to include the thyroid gland when meat is ground into hamburger or sausage. People, and presumably pets, that eat such contaminated hamburger or gullet tissue can ingest doses of thyroid hormone sufficient to induce disease.”
It is significant to note that the thyroid gland is banned from human consumption (ground in hamburger meat) – thus we know it ends up in pet food. But again, consumers are not told which pet foods include the thyroid gland that could put our pets at risk.
The few pieces of science published on this issue all discuss raw pet foods as the risk of diet related hyperthyroidism. It is assumed this is because raw pet foods contain more meat than typical kibble or canned pet foods (thus could contain more thyroid tissue). But…it is my guess that raw pet foods are not the only risk. Any pet food that contains large levels of thyroid glands of slaughtered animals could pose a risk to the pets consuming them.
What can consumers do?
One – call or email the manufacturer and ask if thyroid glands are included in any meat ingredient of the pet food.
Two – know the symptoms of hyperthyroidism. Dr. Mark Peterson states the symptoms of canine hyperthyroidism are: weight loss, aggressiveness, tachycardia (rapid heart rate), panting and restlessness. If you notice these symptoms in your pet, consult your veterinarian immediately.
As the AAFCO meeting will be coming soon, this will be an issue that I ask regulatory authorities about – to label the thyroid gland as a separate ingredient in order to alert consumers. In the meantime, all consumers can do is to ask questions of your pet food manufacturer and pay close attention to your pets.
Wishing you and your pet(s) the best,
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