Depo Provera in cats

Question
We live outside N. America, where Depo Provera can be used in contraception
for cats.  Our Long-haired Himalayan cat just went into heat.  We separated
her quickly from the male cat of the house.  Today is the 2nd day she has
displayed the crouching stance and yowling call.  We don't know if they mated
before we separated them.   Do you know if Depo-Provera can be used safely
if she might have already gotten pregnant?  One local vet said "no problem,"
and another said it may cause complications in delivery.

Answer
Pat,

I am afraid I cannot be of much help for you.  I am checking a book called "The Pill Book Guide to Medication for Your Dog and Cat", by Kate A.W. Roby, V.M.D and Lenny Southam D.V.M.; Bantam Books, NY; 1998.

On Pages 461 - 464, they cover a group of drugs called progestins. Depo-provera is, generically, Medroxyprogesterone Acetate. There is a lot of information on the general use of these drugs.  Under cautions and warnings, the very first one is:

"Do not use in animals that are pregnant or have uterine disease, diabetes mellitus, or mammary cancer."

Personally, I always err on the side of caution if I think a female might be pregnant.

About 21 days after the cats have bred, if she id pregnant, the nipples should become bright pink and prominent.  This will only last a few days and go back to normal until she drops her milk.  One caution is that being in season also has a similar, but somewhat more muted effect on the nipples.

There is a morning after pill you can give the female if you do not want her to be pregnant.  I would tend to abide more by the vet who cautioned you than the vet who said no problem!!!!!

Best regards... Norm.