Dear Dr. Fox — I own a beautiful 3-year-old chocolate miniature dachshund. He weighs 10 1/2 pounds, is well-behaved, and is a very close friend. Mooky has only one testicle. I assume the other one is somewhere in his stomach area. Two vets have recommended that I have him neutered, as both testicles need to be removed. What should I do? Thank you in advance for any advice you can provide. — D.S., Norfolk, Va.

Dear D.S. — My opinion, I am sure, echoes what the other two vets have said. The undescended testicle, which is somewhere inside his abdomen, should be removed. It could turn into a cancerous, Sertoli-cell tumor. This kind of tumor can produce a lot of female sex hormone, essentially feminizing your dog. This situation will reach the point where his pheromones attract male dogs, and their noses will take him to be a receptive female. He will then, most likely, get into fights and detest being courted and mounted.

There is evidence that this problem, called cryptorchidism, is hereditary, so removing both testicles to make sure that the condition is not passed on to male offspring is advisable.

Dear Dr. Fox — I am the proud (well, normally proud) owner of a 5-year-old female basenji/heeler mix. I rescued her about four years ago, and she was very underweight. She got back to a healthy weight, but went into heat, even though she had been spayed.

The vet who spayed her performed exploratory surgery and found that he left bits of ovary in her, which continued to produce hormones. After the remaining bits were removed, she began to gain weight rapidly, about 15 pounds in six months.

I shifted her to a diet of Precise Light Formula. After eating, she is always licking her bowl, eating things off the ground and chewing them. Now she's started chewing my belongings. She has always been an avid chewer of bones and chew sticks, but not my personal things. I can't have her chewing shoes, belts and bookbindings when I leave the house.

Will a change in her diet help change this behavior? — R.B., Eden Prairie, Minn.

Dear R.B. — After being spayed, some dogs suddenly begin to put on weight, a possible endocrine-related hormonal imbalance. Hormone-replacement therapy with DES (diethylstilbestrol) may help, but it has potentially harmful side effects with long-term use.

Most manufactured "diet" dog foods are full of fillers, fail to satisfy dogs' appetites, and may be deficient in essential nutrients.

The supplement L-carnitine can help with weight loss. I would give 250 mg with food, four times daily.

www.twobitdog.com/DrFox Dr. Fox, c/o "Animal Doctor," United Features Syndicate, 200 Madison Avenue, New York, N.Y. 10016