Name(s): Levotabs (Vetus), Soloxine (JPI Jones), Synthroid
(Knoll), Thyrosyn (Vedco), Thyro-Tabs (Vet-a-Mix)
Levothyroxine sodium acts, as does endogenous thyroxine, to stimulate
metabolism, growth, development and differentiation of tissues.
Levothyroxine sodium is absorbed rapidly from the gastrointestinal
tract after oral administration. Following absorption, the compound
becomes bound to the serum alpha globulin fraction. For purposes
of comparison, 0.1 mg of levothyroxine sodium elicits a clinical
response approximately equal to that produced by one grain (65 mg)
of desiccated thyroid. Soloxine is available in uniquely
shaped, color coded tablets in eight different strengths to allow
easy and convenient dosage adjustment.
is the generalized metabolic disease resulting from deficiency of
the thyroid hormones levothyroxine (T4) and liothyronine (T3). Canine
hypothyroidism is usually primary, i.e. due to atrophy of the thyroid
gland. In the majority of cases the atrophy is associated with lymphocytic
thyroiditis and in the remainder it is non-inflammatory and as of
yet unknown etiology. Less than 10 percent of cases of hypothyroidism
are secondary, i.e. due to deficiency of thyroid stimulating hormone
(TSH). TSH deficiency may occur as a component of congenital hypopituitarism
or as an acquired disorder in adult dogs, in which case it may be
due to the growth of a pituitary tumor.
this medicine should be used: Soloxine is FDA approved
for use in dogs; however, it is a commonly accepted practice for
veterinarians to use this medication in cats. The usual dose in
dogs is 0.1mg/10 pounds of body weight. The usual dose in cats is
0.05-0.1mg per cat. The dose is maintained by periodic blood tests
to determine the T4 level. Animals with hypothyroidism are usually
treated with levothyroxine for life.
precautions: This medication should not be used in animals
allergic to it. Do not use in animals with untreated adrenal insufficiency
(Addisons disease), use with caution in animals with high
blood pressure. Use with caution when given with warfarin, theophylline,
digoxin, phenytoin and barbiturates. Give 1 hour before or 4 hours
after vitamin/mineral combinations containing iron or calcium. Always
tell your veterinarian and pharmacist what other medications your
pet is taking. There can be differences in the action of levothyroxine
when changing brands. As a result, it may be necessary to retest
T4 levels when switching brands.