Reproduction Issues in Female Cats


Estrus suppression in cats

Question: Dear dr Mike,

We have a 5 month old female Siamese cat, called Geeta. The cattery we got her from advised us to let here take a weekly hormone pill to prevent her from getting "in heat", when she comes of age, which will probably be within 3 or 4 months. However, our vet advises an operation to remove the ovaries. According to the information of our vet the risk of ovary or other cancers is too great using these hormone pills every week. In your -very useful- site I couldn't find anything about these pills. 1. What is the risk of these cancers to develop with these pills? Have you seen much problems at administering them? Is an hormone injection an alternative? 2. What is the risk of the operation? Is it save to let it preform? Thankyou very much for your answer. I am a subscriber since June. Evert

Answer: Evert-

In the United States, there is no approved product for estrus suppression in cats, that I am aware of and spaying and neutering are utilized to a much higher degree than in many other countries, so there may be less need for such a product in the U.S. market. However, megestrol acetate (Ovaban Rx, Ovarid Rx, Suppress Rx) is approved in some countries for this purpose.

This product does have significant side effects in cats and it should be used with a full working knowledge of the risks involved.

Megestrol acetate is a potent inhibitor of cortisol production in cats, leading to a situation in some cats where surgery or severe trauma such as being hit by a car can induce profound shock that might not otherwise occur. This effect is reversible and will go away when the medication is stopped.

Megestrol acetate frequently leads to hyperglycemia, or a transient diabetes mellitus, which also usually is reversible when the medication is stopped. Sometimes the diabetes will be severe enough to require insulin therapy for a few weeks to a few months before it corrects itself, though.

Many cats will develop mammary gland enlargement (hyperplasia) while on megestrol acetate and a few will develop mammary gland cancer. We have seen this once in our practice, in a male cat.

Other occasional effects are vomiting, diarrhea and personality changes due to hormonal effects. There are infrequent reports of liver damage associated with the use of this medication, as well.

The plus side of megestrol acetate is that you can use it to suppress heat periods for up to eighteen months at a stretch, which can be long enough to allow an evaluation of a cat for breeding purpose or to allow time to make a decision about spaying or neutering for other reasons.

Removal of the ovaries is permanent, which makes it a big decision. I think, like most U.S. vets, that spaying is a better alternative for most cats than long term use of megestrol acetate. But you do have to be sure that is what you want to do, because it can't be undone.

If the cat breeder is thinking of another medication, I can research its effects but this is the only one that I am familiar with.

Mike Richards, DVM 8/29/2000

Assessing age and health of fetal kittens

Question: Dear Dr. Mike,

I've just subscribed and think this site if wonderful. I have two questions 1) My persan cat is evenually carrying kittens after not being able to conceive this year and has been in poor health. She is almost 4 years old She is due at the end of next month and I have scheduled a scan for the 4th to see if the kittens are alive and are in good health because an x-ray will only tell me how many she is carrying and I'm more interested in knowing that they are OK. Do you think the 4th is too early to do the scan, unfortunately the radiologist is on holiday afterwards? but I don't want to waste her time or my money. 2) I have another cat whom I think is pregnant - how can I be sure as she has already just had kittens who are 3 months now and have left home but she is rather round and her nipples are still pink. Thanking you in advance. Jane

Answer: Jane-

There should be no problem with identifying the kittens and determining their vitality at this time. When it is necessary to determine fetal age the best time is supposed to be between 23 and 28 days of gestation and you should be at or past that time if I am interpreting your note correctly. Since you already have an idea of gestation date it won't matter if you are past this time, either.

You could find out if the ultrasonagrapher has time to do a second exam, as it is possible to detect pregnancy earlier with ultrasonagraphy than by palpation. If this cat is calm, it is usually possible to palpate for pregnancy by 18 to 21 days of age. Up to about 35 days it is possible to feel individual lumps in the uterus at the site of each fetus. If the uterus feels swollen but there are no individual lumps, there is a chance that uterine infection is present.

Hope the results are the ones you're looking for.

Mike Richards, DVM 7/29/2000

Feline reproduction questions

Question: Dear Dr. Richards:

I have two other cats - one female and one male - that I have been feeding for a several months. The female was pregnant when I first met them and the male seemed to be just a few months old. I am not sure that they are mother and son. They do not seem to have owners, so I have been feeding them everyday. They do not stay with me but just come and go everyday. The female gave birth to 6 kitten about 2 months ago. I wanted to spay her at once but have not been able to catch her. Now she looks like pregnant again, seeing her belly getting bigger. Here are my questions:

- How soon can a female cat get pregnant after giving birth? - Can you give me some advice how to catch her? - Since she does not stay at home, can she live by herself without my care after spaying? - At what age can a cat get neutered?

Thank you very much again. You have been very helpful. Sincerely, Thandar

Answer: Thandar-

It is not unusual for cats to come into heat about 4 weeks after kittens are born. A few cats will have an estrus period, in which they may become pregnant if bred, at about 7 to 10 days after kittens are born. Most cats will actually have suppression of estrus during the period they are producing milk for the kittens and then come into heat a couple of weeks after the kittens are weaned. So it is possible for a cat to have kittens within 2.5 to 3 months after their last litter of kittens is born, but it is unusual.

The only way that I know of to catch feral (wild) cats is a live trap, such as the ones made by Hava-Hart (tm). We find that it works best to close one end of the trap and put dry food in a line from the opening of the trap across the trigger and into the back corners of the trap, encouraging cats to get fully into the trap. It is important to check traps very frequently because feral cats can harm themselves if left alone in a trap. Trapping is hard and it is easy to catch things like opossums, skunks and even small dogs --- so be prepared with an action plan for opening the trap without getting bitten or sprayed. Using sedatives has never worked for us.

If you can catch her and if you ask your vet to put subcutaneous stitches in the incision, you should be able to release her about 24 hours after spaying, although a little longer is better if she isn't tearing herself up due to being caged. We have spayed and released a few cats, when it was absolutely necessary, and as far as I know they have all done well, but I am still more comfortable waiting until they are really fully awake.

If she is used to taking care of herself she will do fine. Especially if you provide some meals in the first few days.

We are comfortable neutering male cats after 16 weeks of age, but many vets are neutering earlier. I have seen some information on neutering at 8 weeks of age and the kittens in that study did fine.

Hope this helps some.

Mike Richards, DVM 6/12/2000

Residual ovarian tissue - after spay

Q: Dear Dr. Michael Richards, In April you gave me some much appreciated, useful information about sedating (or otherwise calming) cats which are flying internationally. - THANK YOU again. Today I have a different question: My 11 mo. old female, spayed a month ago at 10 months, is in, what seems to be, her second "false heat" post-operation. Her vet tells me that he removed her uterus and ovaries and that a first "false heat" is normal. But 30 days later, a second? She had some "post-op complications" - several days of refusing to eat, altered personality, and then, what her vet told me was, rejection of her internal stiches (a hard lump formed, he lanced it, pus came out and it eventually healed). She is: crying out the window and balcony (to street cats presumably), rubbing and rolling around VERY affectionately, licking her vagina constantly, assuming the crouched crawling position and peddling with her back legs and making the same noises that she made when she went into heat before being operated on. WHERE IS THE HORMONE COMING FROM? I'm baffled. Is this normal? Should I take her to a second vet to get an X-ray to see what organs she (still) has? Should you have a moment to respond, I would greatly appreciate it. Thanks, Sincerely, Elizabeth

A: Elizabeth- By far the most likely possibility with the signs you are seeing is a portion of the ovary remaining in the body and causing estrus behavior. Sometimes there is ovarian tissue in locations other than the expected ones but more often a small portion of the ovary is left in the abdomen during surgery. This must be reasonably easy to do because there is a lot of attention paid to this problem in books dealing with surgery and reproductive disorders. It is best to do an exploratory surgery to find the remaining ovarian tissue and it is best to do this when the cat is exhibiting signs of estrus behavior because the ovarian tissue will be more visible then. I have read accounts of veterinarians checking for residual ovarian tissue and not finding it despite diligent efforts so there is a possibility that hormones are being produced somewhere else in the body that mimic reproductive hormones in a few cases. Despite that, I think the consensus opinion is that this is much more likely to be ovarian tissue overlooked during the spay surgery. Finding it and removing it should resolve the symptoms. I don't think that leaving some ovarian tissue in the abdomen is likely to cause the other signs you saw. Some cats do not tolerate anesthetics well. It may be a good idea to try a different anesthetic combination, especially if induction with isoflurane gas is an option at your vet's. It is much less likely to have long postoperative effects than injectable anesthetics.

Mike Richards, DVM

Weight gain after spay

Q: I have a 2y/o female cat that I had spayed back in April, after the surgery she seemed to gain weight - almost appears full term pregnancy .Someone told me she may have worms or false pregnancy? I was wondering if this was a complication from the surgery

A: Brian- A small percentage of cats will gain weight after spaying or neutering and this may be normal. False pregnancy is not likely as spaying should prevent that from happening. There is some chance of an unrelated illness causing ascites (fluid accumulation) in the abdomen. It would probably be best to ask your vet about this and schedule an examination if your vet believes that would be a good idea.

Mike Richards, DVM

Cat in heat

Q: First of all, thank you for good information. I really thought something "bad" was wrong with my 8 month old kitten until I called the vet. He said I described her as being in heat. I guess I just want to make sure. Can you give me some symptoms?C-

A: Cats exhibit a lot of strange behaviors when they are in heat. Rolling on the floor and rubbing against objects with noticeable intensity occurs. Cats often rub their head or neck on objects as well. Flexing the claws and stretching may accompany the rolling. As estrus progresses the female starts a strange howling that can go on for several minutes at a time. Some females spray urine in the same manner that is usually associated with tomcats - lifting the tail and squirting urine on a vertical surface. She may adopt postures suggestive of a desire to mate - tail raised, rear end elevated. A strong desire to escape the house may develop. Some cats follow their owners around very persistently when in heat.

If your cat is exhibiting several of these signs your vet is probably right. Vets are good at identifying estrus after a few phone calls!

Mike Richards, DVM

Spayed but exhibiting signs of estrus

Q: Dear Dr. Mike, I occasionally cat sit for my neighbor's 1-1/2 year old female domestic short-hair cat, Sadie. Sadie was spayed at about 9 months old, but a few months later she went into heat. The vet performed another spay procedure two months ago, but he wasn't very optimistic because he couldn't find any remaining reproductive tissue. Poor Sadie continues to go into heat. Do you have any suggestions? Thanks for your help.

A: I realize that advising your friend to have the surgery to look for ovarian remnants repeated is not likely to be welcome advice but it is probably the most practical advice. It is best to do these surgeries when the cat is exhibiting signs of estrus, if possible. The ovarian tissue will be easier to find then because the developing egg makes it larger. It is also reasonable to do it shortly after estrus when a corpus luteum (remains of the egg) is present since they are sometimes easier to feel and see due to their consistency and coloring.

If there is any question about whether or not a real estrus period is occurring, examination of vaginal smears and hormonal testing may help to confirm what is going on. Vaginal smears are easy for most veterinary practitioners to do and to interpret fairly reliably. Hormonal testing is less likely to be a routine procedure for your vet (at least in cats) and it may be a good idea to ask about referral to a veterinary reproduction specialist (a theriogenologist) if you get to this point. Even though this is a much more involved process it may be warranted in this case, since no ovarian tissue was found on the first exploratory surgery.

Mike Richards, DVM

Gestation length for cats:

Q: How long is the feline gestation period? Thank you

A: The normal gestation period in cats is 63 to 66 days.

Mike Richards, DVM

Cat in heat, what to do?

Q: I got my cat in May of 1996. I was told she was six weeks old. It is now January 28, 1997 and my cat is in heat. I was planning on having her fixed, but now I will have to wait. Could you tell me how long a cat will stay in heat? She is an outdoor cat and it is very hard now to keep her in the house. Do you have any advise on anything I can do util this runs its course? Thank you for your help.

A: I have no qualms at all about spaying a cat when it is in heat. You might want to check with your vet to see if he or she feels the same way.

Cats are "induced ovulators" which means that they will go out of heat shortly after being bred. If they do not mate, they can stay in heat for several days but most of the time they appear to stay in about 4 to 6 days, then come in heat again in about 2.5 to 3 weeks. This does vary widely and some cats appear to almost constantly stay in heat. They do seem to be pretty miserable but who knows if they really feel that way?

Talk to your vet -- spaying her will provide the quickest relief.

Mike Richards, DVM


Q: What is considered a normal estrus, or "heat" cycle in cats? From everything we have read, they can come into heat several times a year, but there is no mention of the average length of one cycle. Can you help?

A: The estrus cycle of cats is unusual. Cats are "induced ovulators", which means that their bodies attempt to stay in estrus until they mate. This stimulates ovulation which ends the heat cycle. If they are not bred, they may go out of heat in as short a time as few days or stay in heat for a variable length of time. Some cats appear to almost stay in heat continuously. I believe that the average length of time in heat is probably between 3 and 7 days and that the average time between cycles is just under 3 weeks, but that is from memory (my books are at my clinic and I'm at home). The way that cats behave during heat cycles is probably one of the major reasons that people have them spayed. They just seem so uncomfortable!

Mike Richards, DVM

Last edited 03/28/04


Michael Richards, D.V.M. co-owns a small animal general veterinary practice in rural tidewater Virginia. Dr. Richards graduated from Iowa State University's College of Veterinary Medicine in 1979, and has been in private practice ever since. Dr. Richards has been the director of the PetCare Forum...