Dear Dr. Fox:

We have a 5-month-old female golden retriever. On her first visit to my vet after she came home from the breeder, I was told she has hypoplastic vulva. The vet suggested that she go through one heat cycle. He said that this could increase her risk for breast cancer, but right now it is too low to worry about. If we have her spayed before she goes into heat she may have to have surgery on her vulva. This could also lead to bladder infection. He also said this won't guarantee a need for reconstructive surgery.

We have no intention of breeding this dog, and I'm very confused on what we should and should not do. If we have her spayed before a heat cycle, what problems, if any, could we face? What is the benefit of her going through a heat cycle? At what age can we expect her heat cycle to start?

I'm quite worried about having a dog in heat and walking her outside, having male dogs approach her, etc. I have never dealt with a dog in heat before. I would appreciate your advice.

L.W., Reston

I understand your concerns, but agree with your veterinarian that allowing her to go through one heat cycle could help rectify her congenital defect and avert the need for corrective surgery.

It is true that spaying before the first heat reduces the likelihood of breast cancer later in life. But there are many estrogen-mimicking contaminants (especially dioxins and PCBs) in our food, particularly in animal fats and tallow, that are also present in pet foods. So I would strongly urge you not to feed your dog processed pet foods that include tallow on the label, and give her a teaspoon of vegetable oil in her food as a beneficial source of fatty acids.

Handling a dog in heat is no problem. You can purchase (from a pet store) sanitary pads to put on her when she's indoors. Keep her leashed on her walks and take a cane or walking stick with you to push away any canine suitors she may attract. Once-popular chlorophyll tablets were effective in making female dogs in heat less attractive to males, but they're now hard to find.

Dear Dr. Fox:

I have a tortoiseshell/calico cat who is 3 years old. She has a problem when I, the mother of the family, am gone from the house: She gets very violent when I return home.

Recently, I went on a trip to Florida. When I returned she growled, hissed and tried to attack me. Sometimes when I go to see where she is she starts getting nasty. But she can be a very loving cat, too. This behavior is baffling to us and we wonder if you could provide some possible causes and/or solutions.

K.K., Niagara Falls, N.Y.

Sudden and unprovoked aggression in cats is not an uncommon event, with people being threatened, scratched and bitten by normally friendly cats. I have received many letters on this problem. Sometimes the person attacked is wearing a new perfume or smells of another cat, or else there is another cat outside that is upsetting the family cat.

Since there could be a clinical basis for your cat's change in temperament, have her examined by your veterinarian; have her checked especially for hyperthyroidism, which can make cats more irritable and aggressive.

If there is nothing wrong with her physically, dispensing the cat pheromone Feliway (available from your veterinarian) may help. Or try anointing your cat with a dab of the same cologne or perfume you use under her chin and at the base of her tail.

Dear Dr. Fox:

My guinea pig, Lucy, is blind. She can only see light and shadow. Because of this she won't run around. The only place she'll even move is in her cage, and that's if a veggie is three inches in front of her. Exercise is totally unheard of for her -- she already has about five chins, and the family doesn't want her to have any more.

Please help us. Lucy is an important piece of the jigsaw puzzle of our lives.

A.G. (age 9), WashingtonGuinea pigs, also known as cavies, are highly sociable and friendly creatures. Your blind Lucy will have a new lease on life if you get another girl guinea pig for company. They will interact and Lucy will become more active and start to lose weight. The other guinea pig will probably become her seeing-eye guide. Be sure to get a much bigger cage for them (2 feet wide by 4 feet long, for instance), and let them have the run of your room for as long as and as often as you can (making sure to unplug any electrical extension cords that they might chew through, as a precaution).

Write to Michael Fox, United Feature Syndicate, 200 Madison Ave., New York, N.Y. 10016. The volume of mail prohibits personal replies, but questions of general interest may be discussed in future columns.

(c) 2005, United Feature Syndicate Inc.