I don't have experience with I-131 and cats, but I do have personal
experience with I-131. Look at it this way...your cat will be
radioactive until all of the iodine washes out of the system. You do NOT
want to put your newborn baby at risk of any radioactive contamination
as it can damage baby's thyroid! (yours too! but i'd be much more
concerned about a newborn!)

Last summer when I had I-131 treatment, I stayed away from my cats for a
little over a week and did not sleep next to my husband for 5 nites.
However, I was told to stay away from kids, the elderly, and
pregnant/nursing moms for at LEAST 2 weeks and I went a little longer
just to be super safe.

I would think in the case of your newborn baby, being overcautious is a
GOOD idea. :)
good luck!!!
Pam

Definitely-- but she has to cover herself because of NRC regulations.
People over 45 are told to stay 3 feet or farther away from the cat except
for short periods for feeding and routine care.  People  under 45  are told
stay 6 feet or farther away from the cat, and children under 18 and pregnant
women are told to have no contact with the cat for 2-3 weeks.  I received
the same spiel when my cat had the I-131 tx last month.  I was forced into
the treatment, too, because the Tapazole completely killed my cat's appetite
and drove her WBC count down to borderline leukopenia.

Personally, I think the regulation is a tad extreme.  Its based on the
assumption that all cats will receive a large dose.  The cat can't be
released until his surface radioactivity level below is 45 mR/hr- that's
about the same or less than a routine x-ray.  I do agree with not allowing
your wife to handle the cat or clean the litterboxes for a couple of weeks.

A lot of radioiodine facilities use a standard high dose that will destroy
cancerous thyroid if the cat has any.  But only about 2% of feline thyroid
tumors are cancerous.  So, I strongly suggest you speak to the vet who will
be administering the tx about the dose.  My cat's dose was about 1/2 or even
a little less than the routine dose and her 3-week post treatment T4 was .5!
That's *below* the normal range.  She was released 2 days after treatment
because her radioactivity level was far below the 45 mR/hr requirement.  The
lower the dose the faster the cat clears the I-131.

I-131 is one of few drugs that's not dosed according to body weight, but
rather severity of hyperthyroidism.  If your cat's pretreatment T4 levels
aren't very high after he's been off Tapazole for about 10 days, a low dose
would probably be appropriate.  Also, the lower the dose the less chance of
the cat becoming hypothyroid or developing CRF.   Most cats that receive
I-131 tx will become hypothyroid for 1-3 months after tx because it takes
awhile for the normal thyroid tissue to become active again.  The
hyperfunctioning thyroid tissue suppresses the normal thyroid tissue so it
doesn't receive much TSH. Once the hyperfunctioning tissue is destroyed, the
normal tissue can start receiving TSH again and become functional again.

You might want to call a few veterinary universities and speak to an
endocrinologist and a radiologist.  I recommend calling the Animal Medical
Center in NYC.

Best of luck,

Phil