RE: Hyperthyroid Treatment in Dogs

[Karin Gordon <KGordon@exchange.hsc.mb.ca>]

Speak to Sunil Choubal (Head of Occupational safety) at your institution
- he has a great deal of radiation safety experience in this area,
particularly in the radioiodine treatment of cats  with hyperthyroidism.

In humans, the thyroid extracts the iodine from the thyroid gland
quickly and efficiently, the 4-hour uptake is about half of the 24 hour
uptake, which is pretty representative of the final uptake.  The kidneys
are also pretty efficient in excreting the vast majority of iodine not
removed by the thyroid from the circulating bloodstream.  In humans, we
encourage hydration (drinking lots of fliuids, or if that is not
tolerated installing a simple IV saline drip), to enhance rapid
excretion of the radioidodine not taken up by the thyroid gland.  Of
course, all body fluids will contain radioiodine - primarily in the
urine, but sweat and saliva will also be hot.  This presents an
interesting contamination problem in veterinary practice, as cats and
dogs tend to lick themselves as a grooming activity, an activity in
which most of my human patients fortunately do not engage ;>).  

In humans treated for hyperthyroidism, about 50% of the administered
activity is excreted in urine, for thyroid cancer post throidectomy,
about 95-98% is excreted.  From the amount (100 mCi) you are using for
the Tx,  I assume you are either doing a thyroid ablation or treating
metastatic disease.

The University of Saskatchewan has very knowledgeable radiation safety
staff who have dealt with this in the past, so give them a call.

************************************************************************
************************
Karin Gordon
Radiation Safety Office
Health Sciences Centre
GC-214, 820 SherbrookSt.
Winnipeg, Manitoba
CANADA  R3A 1R9

KGordon@hsc.mb.ca           or        KGordon@cc.UManitoba.ca

phone (204) 787-2903
fax      (204) 787-1313



>----------
>From: 	Mohamed Benmerrouche[SMTP:m.benmerrouche@usask.ca]
>Sent: 	December 18, 1998 1:40 PM
>To: 	Multiple recipients of list
>Subject: 	Hyperthyroid Treatment in Dogs
>
>Hi,
>
>We are planning to treat a dog with 100 mCi of I-131 and I am wondering if 
>anybody can provide me with
>any information (such as web references, own experience, contact persons). 
> In particular  I am interested in the release concentrations of I-131 in 
>the room where the dog is kept. In order to answer this question, I need to 
>know how much of I-131 goes to the thyroid, urine, feces and saliva.
>How long would it take to release all the I-131 through biological means 
>(e-g in humans 30% of iodine  concentrates in the thyroid and peaks 72hrs 
>later). This will also help me figure out the length of time that the dog 
>is required to stay in the clinic to
>ensure the dose rate does not exceed 10 uSv/h, 30 cm away from the thyroid. 
>If I understand no much is
>known on hyperthyroid treatment in dogs as compared to cats!
>
>Any help is greatly appreciated. Please reply to my private e-mail account 
>given below.
>Thanks
>
>M. Benmerrouche, Ph. D.
>R.S.M
>Univ. of Saskatchewan
>m.benmerrouche@usask.ca
>
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