Canine
Hypothyroidism
Hypothyroidism
is a common disorder in middle-aged to older dogs characterised by a
reduction of thyroid hormone production. Many breeds are commonly affected
by this disease, for example: Boxers, Cocker Spaniels, Golden Retrievers,
Labs, Poodles, Dachshunds and Miniature Schnauzers. It is likely that some
breeds are genetically predisposed. There is no difference in frequency of
occurrence between males and females.
Thyroid
hormones affect almost every organ in the body and thus many signs of this
disease are common. These include lethargy, depression, obesity despite
normal feeding amounts, hair loss, skin and ear infections, weak or torn
knee ligaments. Should this disease be suspected initial screening
bloodwork is performed. Dogs that are hypothyroid have thyroid levels that
are almost always below the normal range.
Supplementation
of thyroid hormone by pills is the treatment for hypothyroidism. In
general twice a day administration for 6-8 weeks is started. Most dogs
show marked improvement in activity levels within 1 month of beginning
therapy. Improvement in skin and a reduction in body weight may not be
observed for several months. Retesting the thyroid levels 6-8 weeks after
starting therapy is recommended and d dosage adjustment is made if
necessary. Supplementation is for life.
Excessive
administration of thyroid supplement rarely occurs. Side effects may
include hyperactivity, ravenous appetite and weight loss. Signs resolve
within 1-3 days of stopping treatment and re-evaluation and dosage
adjustment is usually necessary.
The
long term prognosis for dogs with hypothyroidism is good to excellent.
Clinical signs and laboratory abnormalities are reversible with
appropriate treatment. Some dogs are effectively managed on a once a day
dose.