What you need to know and no one is talking about...


I feel compelled to share this information after going through my dog's struggle to find help with this disease.  I am dedicating this page on our website to educate dog owners about The Hypothyroid Epidemic in our country for other dog owners who know something is "off" with your dog but you can't figure out what! Marco started acting aggressive toward my other dogs, he started retreating, and became overly fearful of everyday normal things.


This page is going to talk about Hypothyroid, one of the most common disease in our dogs but is going misdiagnosed.  I will explain how it is directly related to BEHAVIOR ISSUES and many symptoms that present like other illnesses which can be confusing for the animal medical community.  I will also provide you with resources that were helpful to me during our five month battle, with six different veterinarians (included neurology specialists) to finally get him the help he needed. 


You can read Marco's full story about what we went through, when he was diagnosed at only ate 3 years old. And how I was turned away time and time again told my dog was "normal" and how he almost died from repeated misdiagnosis HERE.

The Whole Dog Journal

"Mood swings and unexplained aggression can be caused by low thyroid."

By Shannon Wilkinson




"Many people are aware that hypo-thyroidism (low thyroid function) is a medical condition that can cause an afflicted dog to become lethargic, dull, and fat. But far too few dog owners are aware of the behavioral symptoms that hypothyroid can cause. This is unfortunate, since these symptoms include unexplainable aggression, so-called “rage syndrome,” severe phobias, and cognitive disorders. Lacking an explanation for the sudden onset of these serious behaviors, and gaining no improvement through training, many owners tragically opt to euthanize these troubled dogs.


If an afflicted dog is very lucky, however, his owner will ask a veterinarian to order blood tests that can confirm a diagnosis of hypothyroidism; the treatment is simple and not expensive.Dogs who suddenly become aggressive should be tested for low thyroid. Unaware the behavior may be linked to a medical problem, some owners turn to training methods. This may help, but can’t solve the underlying problem. Other owners may give up.  It’s important to ask, however, since not many veterinarians are aware of the prevalence of hypothyroid’s behavioral signs.



Dr. Dodds and other veterinarians and researchers have been linking changes in behavior to hypothyroidism for more than a dozen years. The various types of abnormal behavior can be grouped into three categories: aggression, extreme shyness, or seizure-like activity.


The cases involving aggression are often similar to Hannibal’s. A previously even-tempered animal lashes out at another animal or human without any warning. One such dog under the care of Dr. Dodds was successfully participating in performance events. One day the dog’s behavior changed radically and he “would go berserk” every time he saw people he didn’t know. Soon he was banned from the training facility because his aggressive behavior had escalated to dangerous levels. Sadly, it’s not unusual for dogs with untreated hypothyroidism to become so aggressive that their owners are no longer able to manage them.


On the other end of the behavioral spectrum are the dogs that become very shy and fearful due to hypothyroidism. While not a threat to humans, extreme manifestations of this kind of behavior still render the dog difficult, if not impossible to keep as a family pet. In addition, these animals are unlikely to be able to continue any activities such as obedience, showing, or working.  The final type of behavioral aberrations seen with hypothyroidism is sudden onset of seizure activity. According to Dr. Dodds, these dogs “appear perfectly healthy outwardly, have normal hair coats and energy, but suddenly have a seizure for no apparent reason.” The seizures may be infrequent, and may include aggressive behavior immediately before or after the seizures.



It used to be that the stereotypical dog with hypothyroidism was middle-aged and a mid- to large-sized breed. Today, says Dr. Dodds, “the majority of dogs diagnosed with hypothyroidism are young adults. They’re one and a half, not four or five like we used to see.”

And there no longer seems to be a link between size and thyroid dysfunction. The top 20 most-affected breeds range in size from Rhodesian Ridgebacks to Maltese.



Any time a dog presents with a behavior problem, particularly one of sudden onset, it is recommended that the owner take the dog to a veterinarian for a full physical exam, complete thyroid panel, blood chemistry/CBC, and urinalysis. After all, a dog can have something as simple as a urinary tract infection and be in horrible pain, causing the unusual behavior.  You have to be particular about the thyroid test, however. Insist on having your dog’s blood sent to a reputable laboratory and tested for all the thyroid hormones and autoantibodies to those hormones. In-office thyroid tests, or simple tests of your dog’s “total” T4 levels, are inadequate for diagnosing hypothyroidism.


Research done at Auburn University indicates that in-house T4 tests are unreliable and inaccurate about 52 percent of the time in dogs. “Having treated lots of animals for hypothyroidism, the most important thing I can recommend is the panel versus the total T4. Every time I think that you can tell something from doing just a total T4, I’m mistaken,” says Dr. Pressler.  In addition to the possibility of inaccurate readings, the total T4 can be in the “standard” reference range, but too low for a particular dog’s age, breed, or size. And the other levels found in a full thyroid panel give a much clearer picture about how the thyroid is functioning. A complete thyroid panel tests these six levels, plus TgAA:


Total levels of thyroid hormones thyroxine (T4) and Triiodothyronine (T3)
• The availability of T4, as indicated by “Free T4” (FT4)
• The availability of T3, as indicated by “Free T3” (FT3)
• The autoantibody levels of T4 (T4AA)

• T3 (T3AA)

• TSH (Thyroid Stimulating Hormone)


Dr. Dodds says that testing for autoantibodies is particularly important, because elevated levels of autoantibodies indicate thyroiditis, regardless of T4 or T3 levels. “Those animals are having inflammatory immune-mediated lymphocytes attack and damage the thyroid gland,” she explains. It’s important to proactively treat these dogs, she adds, because when you’re dealing with behavior issues, the dog could end up with serious aggression before the total T4 ever tests too low.


Don’t let recent “normal” tests keep you from suspecting thyroid issues, should your dog’s behavior change suddenly. Hannibal had a full blood panel in July, which included T4, which came in at 1.4. At that point, he was acting normally. His behavior started to change subtly until he had the three incidences of aggression, and he was diagnosed as hypothyroid in November.


Results that are in the normal levels as dictated by the lab aren’t necessarily normal for your dog. Dr. Dodds has fine-tuned the optimal levels for different ages and breed types. Generally speaking, younger dogs should have higher thyroid levels (in the top half of the “normal” range). Geriatric and large- or giant-breed dogs have “normal” levels that are closer to the bottom part of the normal range. Sighthounds normally have very low basal thyroid levels.



The standard treatment for hypothyroidism is hormone replacement with a synthetic T4 compound, L-thyroxine, often called by the brand name Soloxine. Depending on the dosage, a month’s supply for an average-sized dog costs between $5 and $10. Once diagnosed, Dr. Dodds starts treatment. The standard dose is 0.1 mg per 12-15 lbs of optimum bodyweight twice daily.“The half life is 12-16 hours, so we don’t recommend putting them on once a day ever,” says Dr. Dodds, despite some people’s experience that their dogs do “fine” on once a day dosing, and some medication labels give once per day dosing instructions.


Finally, Dr. Dodds suggests that thyroid medication be given to the dog directly by mouth, rather than in the food bowl. Owners who feed their dogs home-prepared diets are warned not to give the medication within a half-hour of a calcium-rich meal, such as meaty bones or a dairy-rich food, as it will interfere with absorption of the medication.



In addition to thyroid medication, Dr. Dodds recommends certain supplements and remedies for dogs with hypothyroidism and behavior issues in particular. “We use flower essences to calm agitated dogs. Give them Rescue Remedy before or during high-stress situations,” she suggests.Glandular supplements are an obvious choice for dogs with endocrine dysfunction (see “Grand Glands,” WDJ March 2003). But when you’re dealing with a risky behavior case, medication is the right place to start, says Dr. Dodds. She’s had patients who are reluctant to use any kind of drug.“I can understand where they’re coming from; they want to use glandulars, but they keep shoveling them in and they don’t work. That’s no good, especially if you have a behavior case, where you can’t take a chance.”



Most of the cases that Dr. Dodds sees have responses like Hannibal’s. “I would say at least 80 percent of the cases have a remarkable improvement; it’s unusual to have them not improve.”  Even more gratifying, the improvement is often quick. Most animals show improvement from two days to two weeks after starting treatment; some may take up to 30 days. Interestingly, a collaborative study between Dr. Dodds and Tufts University has shown many dogs experiencing aggression issues, as a symptom of hypothyroidism, show a favorable response to thyroid replacement therapy within the first week of treatment, even when it took about three weeks to correct the metabolic deficit.


Follow-up blood work should be performed six to eight weeks after medication is started. Blood should be drawn four to six hours after dosing to monitor the dog’s response. Dr. Dodds considers results that are between the upper third of the lab’s “normal” reference range to 25 percent above that to be optimal.  She also recommends a complete thyroid profile at the time of the recheck. “It is essential for animals with autoimmune thyroiditis to determine if the autoantibodies are waning,” she explains.  In most dogs, the autoantibodies begin to decline after treatment starts. This is significant in that it indicates that the autoimmune destruction of the gland is declining or even stopping. But it doesn’t mean the dog is cured. It’s important to maintain the dog’s medication to keep a recurrence of the thyroiditis at bay.


"The Canine Thyroid Epidemic"

- Dr. Jean Dodds




"Each year, countless dogs suffer needlessly-and many die-from an easily treatable condition knows as canine thyroid disorder.  Thyroid disease is sweeping through the canine community at such an alarming rate that it has reached epidemic proportions.  Most dog guardians do not know how to spot the clinical symptoms of the thyroid disease in their four-legged friends, and many veterinarians are unaware of how to proerly test and diagnose their patients to determine if they suffer from a thyroid disorder.  Unfortunately, this confusion on both the part of the dog guardians and veterinary professionals set up a "perfect storm" of misunderstanding, misdiagnosis and mistreament (or often complete lack of treament) of canine thyroid disorder, and our dogs are the ones who suffer.


From seizures and obesity to chronic infections, mood swings, and a wide range of other serious conditions our dogs are being ravaged by a debilitating and confounding "epidemic."  And we humans have alot to do with it. We are breeding them, feeding them, and rearing them toward a life of genetic weakness, ill health, and an inability to tolerate their toxic environment."



Behavioral and psychological changes have been asociated with thyroid dysfunction in humans for several hundred years, but hypothroidism also plays a key role in the mental health of our canine friends.  Hpothyroid dogs-especially younger dogs with autoimmune thyroiditis-can display a wide variety of abnormal behaviors.  Today in spite of how animals have been bred and selected for their behaviors over several thousand years, milions of them are being destroyed annually due to behavioral problems.  With thyroid-related behavior issues, a quiet, well-mannered, and sweet-natured dog may suddently show signs of moodniess, erratic temperament, lack of concentration, depression, mental dullness, anxiety, fearfulness, and other uncharacteristic behaviors.  These changes can progress to sudden unprovoked aggressiveness in unfamiliar situations with other animals, people and especially with children.


Body processes controlled by the hypothalamic-pituitary-thyroid axis include:

Metabolism, Cell growth, Tissue Function, Enzyme production, Organ function, Brain development, Mood regulation, Growth and maturation,  Sexual processes, Reproduction, Cell oxygenation. BASICALLY EVERYTHING!

Even though hypothroidism is the most frequently recognized canine endocrine disorder, it is still difficult to make a definitive diagnosis of the condition.  Since the thyroid gland regulates metabolism of all of the body's cellular functions, reduced thyroid function can produce a wide range of clinical signs.  Many of these signs mimic those of other disorders and illnesses, making recognition of a thyroid condition and proper interpretation of thyroid function tests confusing and problematic for veterinarians. 



There are a lot, every dog presents differently, but the *stars indicate Marco's symptoms*


Normal thyroid function affects just about every aspect of a dog's health, including:

*Maintaining healthy skin and coat

* Maintaining proper body weight

*Promoting mental alertness and concentration

*Fighting infections

Maintaining the body's temperature

Controlling growth and maturation

Facilitating normal reproduction


Alterations in cellular metabolism:


*Weight gain

*Mental dullness

*Cold intolerance

*Exercise intolerance

*Mood swings

*Neurologic signs (polyneuropathy, stunted growth, seizures)

*Chronic infections



Neuromuscular problems:


Knuckling or dragging feet


*Muscle wasting

Laryngeal paralysis


Facial paralysis

Head tilt

*Tragic expression

*Drooping eyelids


Ruptured cruciate ligament


Dermatologic diseases:

Dry, scaly skin and dandruff

Chronic offensive skin odor

Coarse, dull coat

*Bilaterally symmetrical hair loss

Rat tail

Puppy Coat

Seborrhea with greasy skin

Seborrhea with dry skin


Pyoderma or skin infections myxedema


And the list goes on... Reproductive disorders, Cardiac abnormalities, Gastrointestinal disorders, Hematologic blood disorders, Ocular eye diseases, other associated disorders.





Our canine companions are becoming afflicted with hypothyroidism and thyroid dysfunction at an unprecedented early age.  In recent years, an increasing number of sudden thyroid-related behavior changes have been documented in dogs around the time of puberty or as young adults.  Younger dogs may show minor signs of thyroid disorder before the condition deteriorates to the sudden onset of



These "early warning signs" in puppies and young adults include:  Inattentiveness, Fearfulness, Seasonal Allergies, Skin and coat disorders;Dermatitis, Alopecia and Intense Itching


Imagine that your quiet, sweet natured puppy suddenly changes in personality as he enters into puberty or shortly thereafter.  Your previously well-mannered and outgoing pet now acts like a different dog, displaying one or more signs of abnormal behavior, would you know what to make of these symptoms?  That there may be a possible underlying physical condition?  All too often owners struggle with their dogs behavior because of these issues and many dogs are relinquished and put to death:





*Schizoid behavior

*Fear around strangers



*Failure to be attentive


Adult Dogs

*Aggression (unprovoked towards other animals and/or people)

*Seizures (sudden onset in adulthood)



*Erratic temperament




*Fearfulness and phobias








One of the reasons it is so important to trust your instincts is that since you spend so much time with your dog, you may witness physical and behavior changes in them that are demonstrated during the time you visit your vet clinic.  Recognizing these changes, keeping a diary and taking video whenever you notice something that concerns you is helpful.



As you can see your dog's physical wellbeing relies on having a proper thyroid in balance. Hopefully you have carefully screened potential veterinarians ahead of time, you will have found one that not only possesses excellent professional credentials, but also treats you as a partner in yor dog's health care.  Such a veterinarian will respect your opinion and listen to your concerns and suggestions with an open mind.  The bottom line is you should never have to feel uncomfortable with the way your vet treats you.  Yes they are an expert in their field but they do not know your dog like you do.  This is serious business and could in fact, be a matter of life or death.  There is no place for egos when it comes to your dog's heatlh.  If your veterinarian is putting their ego before their desire to hear potentially valuable information from you, you should politely part ways and find someone willing to help you.  You must be the advocate for your dog! You must speak for you dog, just as you would for your child. TRUST YOUR INTUITION. If you sense that something is not right with your pet, don't let an "expert" convince you that you are wrong. Stay on the case until you reach a statisfactory solution. Believe in yourself. Your canine companion is depending on you!