Aggressive Behavior May Be Linked To Thyroid Disease
Marget Johnson
by Connie Vanacore and published in the June 19 issue of "Dog News":
"Aggression is one of the primary reasons which impel owners to either give
their dogs to shelters or euthanize them. There are many causes for aggressive
behavior, both medical and psychological. Sometimes it is difficult to
diagnose why a dog becomes antisocial, especially if the animal has had a
history of normal behavior. It is important for a dog who either suddenly or
gradually becomes aggressive to be throughly examined by a veterinarian.
In an article in the May 1992 "DVM Newsmagazine", W. Jeans Dodds DVM [Cornell]
explores the possible underlying causes of aggression in dogs.
She says that inheritance has been shown to play an important role in
behavior, but that behavior is complex because it not only reflects the
functioning of the animal but changes in response to environmental influences.
Dr. Dodds claims to have noticed in recent years a sudden onset of behavioral
changes in yloung dogs coincident with the beginning of puberty. Many of the
same animals have shown seasonal allergies to inhalants and ectoparasites.
Symptoms begin to appear anywhere from 7 months to 1 year of age and can take
many forms. Normally responsive dogs may become nervous, fearful in the
presence of strangers, disoriented and inattentive. SOme may become aggressive
to other animals and people, especially children. Some may hyperventilate, be
unable to handle stress or begin to have seizures of varying frequency.
When clinical workups were initiated on many of these animals significant
abnormalities were found in the thyroid profile. Some cases also had changes
in liver enzyme patterns.
The diagnoses were made as autoimmune thyroid disease induced by some type of
physiological change at the cellar level. When the dogs were treated with
appropriate doses of thyroid hormone given twice daily along with a 1-month
tapering course of low-dose corticosteroids, behavioral problems were reversed
within 4-8 weeks. Dogs who are tested and found to have low or low-normal
thyroid levels must be maintained on hormones for life, with occasional dosage
adjustments.
According to Dr. Dodds, the results of thyroid supplementation for the dogs
she studied were dramatic, but she also recommends avoiding the environmental
factors that can further challenge the immune system. She recommends feeding
these dogs a hypoallergenic diet preserved without chemical additives and
avoiding drugs which may alter the immune system. She also recommends
withholding vaccination boosters until the thyroid function is properly
balanced and behavioral abnormalities are resolved."
Note from poster: I routinely do thyroid testing of my Newfs, at one year of
age and annually thereafter. The endocrinology lab at Michigan State is
regarded as the best in the nation. It costs no more to require that your vet
use this laboratory to evaluate you dog's thyroid functioning, and you are
assuring that your dog gets the best lab workup possible. As an aside, sulfa
drugs such as Sulfa-Trim, Di-Trim, SMZ-TMP, etc can temporarily change the
level of thyroid hormone, thus resulting in false "Low or Low-Normal"
ratings of blood samples taken from dogs on sulfa drugs.
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