A sodium levothyroxine product approved for use in dogs is recommended. Liquid and tablet formulations are effective. The initial dosage is 0. Twice-daily administration is recommended initially unless the levothyroxine product has been specifically formulated for once-daily administration.
Because of the variability in levothyroxine absorption and metabolism, the dose and frequency may have to be adjusted before a satisfactory clinical response is observed; this variability is one reason for monitoring therapy in dogs. Thyroid hormone supplementation should be continued for a minimum of 4 weeks before critically evaluating the effectiveness of treatment.
With appropriate therapy, all clinical signs and clinicopathologic abnormalities associated with hypothyroidism are reversible. Improvement in mental alertness and activity usually occurs within the first week of treatment; this is an important early indicator that the diagnosis of hypothyroidism was correct. Although some hair regrowth usually occurs within the first month in dogs with endocrine alopecia, it may take several months for complete regrowth and a marked reduction in hyperpigmentation of the skin to occur.
Initially, the haircoat may worsen as large amounts of hair in the telogen stage of the hair cycle are shed. Improvement in neurologic manifestations is usually evident within days of initiating treatment; complete resolution of neurologic signs is unpredictable and may take 4 to 8 weeks or longer before it occurs.
Biologically, it's a once-a-day drug. It also holds true with both name-brand and generic formulations. A caveat while we're on the subject: As mentioned, the half-life of thyroxine in dogs is 10 to 16 hours compared with a 7-day half-life in people.
This means canine dosages are much higher than human dosages. So remember this if clients choose to fill prescriptions for their dogs at pharmacies that do not routinely handle veterinary prescriptions. You may have to do some educating of those pharmacy personnel.
Once canine hypothyroidism has been diagnosed, what are Dr. Bruyette's recommendations for laboratory monitoring? He says that many veterinarians, including those attending this CVC session, were taught that they should draw blood for T4 testing from four to six hours after the thyroid hormone pill was administered. Therefore, the post-pill test is probably physiologically meaningless. If you have clients who own dogs that have been receiving two levothyroxine tablets each day and you decide to revise their dosage to once a day, how do you break the news to the client?
Most owners will be comfortable with the new recommendation. They understand that medical science marches on and drug regimens change as research determines they should. You will want to explain that your previous dosing was based on the published recommendation at the time and that you keep current through your reading and continuing education.
Based on updated information, you are recommending a change in the dosage. If, however, you encounter a client who is upset by and resists the change, according to Dr.
Bruyette, it does not harm the dog to continue administering two tablets a day. The evening dose, the dog will defecate. It will not hurt the dog. He recommends starting any newly diagnosed patients on the once-a-day dosing, but whether you transition the current patients from b. So, is there a way to confirm a dog is euthyroid when it is receiving thyroid hormone supplementation? If the TSH is normal, the dog is euthyroid. The initial recommended dose is 0. Dosage will need to be monitored and adjusted to achieve the correct maintenance dose.
Blood work should be kept up to date to ensure proper dosing. If a dose of Levothyroxine Sodium is missed, give the dose as soon as you remember. If you remember when it is almost time for the next dose, skip the one you missed and get back on your regular schedule. Do NOT double the dosing. When given at the correct dose, there are no known side effects associated with Levothyroxine Sodium.
High doses of Levothyroxine Sodium may cause:. Immediately contact your veterinarian if you think your dog has any medical problems or side effects while taking Levothyroxine sodium. Differences exist between different brands; do not change brands if possible. If you need to change, please consult with your veterinarian as blood work may need to be rechecked to verify correct dosing.
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