Dear Dr. Fox: In Desmond Morris' book "Catlore," he says the spaying of female cats and the castration of males are unnecessary and cruel operations (he calls it "butchery") that dramatically change a cat's personality. Tying the female's fallopian tubes and performing a vasectomy on the male will avoid cat overpopulation.

Do you agree? Does this also apply to dogs? My dog Blake, who passed away three years ago, was neutered. My vet assured me it would have no ill effect on his behavior. I had my doubts, but I went along with it.

I'm getting another dog. What is the right thing to do? -- A.D., Lynbrook, N.Y.

Dear A.D.: I have known Desmond Morris for many years and respect his work, but when it comes to helping cats adapt to their domestic environments, neutering is a humane decision. It is not butchery.

Of course, population control is an important issue in communities where people allow their un-neutered cats to roam free. Biologist Dr. Morris is responding as a purist and, in theory, he is correct.

But the behavioral and medical health benefits of neutering dogs and cats far outweigh the risks and side effects that can generally be corrected. For details, see my Web site, www.twobitdog.com/ DrFox.

It is an anthropomorphic notion that neutering animals deprives them of a basic desire that is their natural right or entitlement to fulfill. Few animal species match the human in terms of sexual motivation or desire, the consequences of which contribute to overpopulation, violence and assorted perversions -- unique in our species in terms of prevalence.

Dear Dr. Fox: I have an 8-year-old terrier/border-collie mix. She's the greatest dog anyone could ever have, except for one annoying habit: She barks at everything, including the moon.

She gets me up in the middle of the night to go outside and once there, she starts barking. This is so annoying, and I can just imagine what my neighbors are thinking.

Even inside the house, if she wants a treat or to go for a walk, she sits in front of me and barks until I give in. I know she's spoiled, but she never used to bark all the time like she does now.

Is there anything I can do? Getting after her for barking does nothing. -- H.N., Bloomington, Minn.

Dear H.N.: Moon barking and barking at jet planes and their trails in the sky seem to be common traits in border collies and Shelties. Just accept it as part of their character and visual acuity.

One of my old dogs always barks as soon as she goes out, as though to tell the world and perhaps to check if there are other dogs around who might answer her. She may be checking whether the coast is clear or simply proclaiming her existence.

Barking in front of you for a treat or a walk is her way of training you.

Ignore, and say "No, later." Try motivation training so she responds only when you want her to. Shout her name, then get her attention by shaking a can of coins or squeezing a dog-training clicker, then make her sit and stay.