I sit before my computer with not a clue what to write about after many years of contributing to these veterinary columns. Normally inspired by on-the-job experiences, I suddenly feel void of ideas. Over the years, I have aspired to educate about every ailment that can occur for every part of a pet’s body. Now faced with writer’s block, I turn to the nearest thing to me (literally lying on the floor next to me) for inspiration … my Border Collie, Jimmy.
My husband and I have always shared our home with a minimum of two dogs, the average being three. The latter is the exact number today. Jimmy is the middle child, flanked by his older, epileptic , half-sister, Robbie, and the younger, animated Welsh Corgi, Betsy Louise. With two “alphas” bossing him around, Jimmy learned quickly to be a “beta.” I like to call Jimmy the brightest bulb in the pack, not only because he figured out this social hierarchy early on, but also because he is frankly very intelligent. In short, Jimmy is the easy child.
While Robbie, at age 14, is in the winter of her life, and still taking high doses of anticonvulsants, and Betsy Louise has torn ligaments in both of her knees, Jimmy’s only ailment has been hypothyroidism, a condition that isn’t flashy, nor difficult to treat. In fact, like Jimmy, hypothyroidism is very easy to manage.
Hypothyroidism, or low thyroid function, is thought to be caused by a dog’s immune system attacking its own thyroid glands. This autoimmune activity results in low production of thyroxine, the hormone of metabolism that turns food into fuel.
As many as 60 percent of middle-aged, large breed dogs will become hypothyroid. In addition, certain dog breeds are over-represented when it comes to low thyroid function and these include Golden and Labrador Retrievers, Dobermans, English Bulldogs, Boxers, Great Danes, Dachshunds, Cocker Spaniels and, of course, Border Collies.
Symptoms of low thyroid function may include thinning hair, pigmentation of skin, sluggishness, weight gain, slow heart rate, muscle wasting, skin and ear infections, intolerance to cold, infertility and mental dullness. Some dogs will only experience neurologic symptoms such as seizures, balance disorders and facial nerve paralyses.
Diagnosing hypothyroidism involves a simple blood test to measure the dog’s Thyroid Stimulating Hormone produced by the pituitary gland in the brain, as well as its levels of Total T4 and Free T4 hormones produced by the thyroid glands themselves. The classic canine hypothyroid patient will have high levels of TSH in the company of below normal levels of TSH.
Jimmy, and all hypothyroid patients, are treated by administration of economical, twice-daily doses of a manufactured hormone in tablet form called levothyroxine or L-thyroxine. This prescription medication is available in a variety of strengths because each dog’s needs are unique. Once diagnosed and treated, follow-up testing to verify dose accuracy, and periodic blood monitoring, are essential to keeping hypothyroid dogs in good regulation and health. Treatment of hypothyroidism will then be lifelong.
If not diagnosed and properly treated, low thyroid hormone levels can result in a rare, but life-threatening myxedema crisis. Common to Doberman Pinschers, symptoms of this medical emergency include hypothermia, extreme weakness, mental dullness and thickened facial skin above the eyes and along the jowls. Pet owners often do not recognize this oncoming crisis because it is gradual in onset, but serious at its peak.
All too often dog owners assume that their pet is slowing down simply due to growing older, when in fact they are “growing hypothyroid.” Appropriate and timely diagnosis of this readily treated malady makes a huge difference in the patient’s quality of life. Because of this, hypothyroidism is a condition I truly love to diagnose and treat.
Just ask Jimmy as he is about to celebrate his 11th birthday and acts like a puppy since on thyroid medication.
Dr. Bonnie Jones practices at Delphos Animal Hospital with her husband, John H. Jones, DVM. She was valedictorian and Outstanding Senior Clinician of The Ohio State University College of Veterinary Medicine Class of 1985.