Page 3325 - Cote clinical veterinary advisor dogs and cats 4th

Consent to Perform Iodine-131 Therapy for Hyperthyroidism

VetBooks.ir Patient name:_________________________________
Pet owner’s name:_____________________________ Med rec #____________
Best contact during/after procedure (e.g., cell phone number):____________________

INTRODUCTION eliminated, causing them to develop the opposite problem—hypo-
We want to make sure that you understand the planned medical thyroidism. In such a case, daily thyroid supplementation (oral tablets
procedure to be performed on your pet. You should know why the given every day at home) might be required.
procedure has been suggested, what the potential benefits are for Cats with hyperthyroidism often have heart disease and/or high
your pet, and the most common/important risks of the procedure. blood pressure that can be life-threatening. Although I131 does
Alternatives to this procedure, when applicable, will be discussed not make these problems worse (in fact, the goal is to make them
with you. It is also important that you recognize that medicine is better), it is possible that your cat could worsen while in radiation
not an exact science, and that the outcome cannot be guaranteed. isolation before the treatment has a chance to work. Because
We encourage you to ask us as many questions as required for treated cats must remain in isolation, recognition and treatment
you to make a well-informed decision. of these conditions can be much more difficult than it would be
otherwise.
BENEFITS/OPTIMAL OUTCOME OF THE PROCEDURE The most important risk is not so much a risk of I131 as it is a
Iodine-131 (I131) is often used to treat hyperthyroidism, which is risk of effective treatment of hyperthyroidism by any method. That
a common disease in older cats. This therapy generally is very is recognition of kidney disease. Kidney disease is very common
safe and does not require surgery, general anesthesia, or daily in older cats, as is hyperthyroidism. Of course, hyperthyroidism
medications, and if offers the chance to cure the disease. is very bad for a cat’s health and can cause heart failure, high
blood pressure, vomiting, weight loss, and a host of other severe
EXPLANATION OF THE PROCEDURE problems. However, it also increases blood flow to the kidneys.
Iodine-131 therapy for hyperthyroidism in cats involves giving a This can make the kidneys “appear” to be better than they really
single injection of radioactive iodine. This iodine concentrates in the are on blood tests and mask underlying kidney disease. If this is
thyroid gland and emits short-distance radiation to kill overactive the case, once the hyperthyroidism is resolved (by any method of
thyroid cells. After the injection, your cat will need to stay in an treatment), the kidneys may not work as well as we thought they
approved radiation isolation ward until his or her radioactivity drops had before treatment and in turn, in some cases, this requires
to an acceptable level to go home. During the time in isolation, your treatment or shortens life span.
cat will be checked on daily and given food, water, and a litter box,
but you will not be allowed to visit because physical contact with Other anticipated risks specific to your pet:___________________
people is restricted. Depending on the local rules and regulations,
most cats are cleared to return home in just a few days. Even _________________________________________________________
after discharge from the hospital, your cat will still be emitting a
low level of radioactivity and his or her urine and feces may be
radioactive for several weeks. Contact with radioactivity should be ALTERNATIVES TO THE PROCEDURE
limited according to the guidelines provided to you to reduce your Alternatives to I131 treatment include medical management with
exposure. It is especially important that your cat avoid contact life-long daily medications (e.g., methimazole), feeding an exclusive
with young children or pregnant women for at least several weeks. life-long special diet, surgical removal of the abnormal thyroid
Additional procedures planned for your pet at the same time tissue, or destruction of the thyroid gland by nonsurgical means
as the iodine-131 therapy for hyperthyroidism: (ablation). Each of these alternatives offers disadvantages as well
as advantages to I131 treatment, and we can discuss the options
____________________________________________________________ with you further if you wish.

USE OF SEDATIVES OR ANESTHESIA AUTHORIZATION
Sedation may be needed for your cat to hold very still during the By signing this form below, you agree that:
administration of the dose of radioiodine. Sedation would involve • You understand how/why the procedure is likely to help your
the administration of medications that cause your cat to become pet
drowsy and relaxed, but to remain conscious. A sedated cat remains • You understand what will be done to your pet during the
in control of vital functions such as breathing. In general, there are procedure
fewer risks associated with sedation than with general anesthesia, • You understand the known risks that accompany the procedure,
but adverse events occur very rarely. and also understand that unforeseen complications may occur
• You understand that the procedure may not produce the results
FORESEEABLE RISKS TO THE PROCEDURE we hope to achieve
This form of treatment is considered very safe for your cat. Although • You understand the alternatives to this procedure for your pet
most cats are cured of hyperthyroidism by a single injection of I131, • You agree that you have been given time to ask questions regard-
≤ 5% of cats will either relapse or require a second treatment. An ing the procedure, that these have been answered satisfactorily,
additional 5% may have too much of the normal thyroid tissue and that you are free to decline the procedure.

From Cohn and Côté: Clinical Veterinary Advisor, 4th edition. Copyright © 2020 by Elsevier Inc. All rights reserved.