Dear Christopher Cat: A stray cat adopted us. Our veterinarian said Dusty is a young, neutered male without microchip identification. She confirmed that he is healthy, and she vaccinated him.

The problem is that Dusty is acting like a tomcat. He’s spraying, and he’s cranky when we won’t let him outside. What can we do?

Christopher Responds: Your veterinarian described Dusty as a neutered male because she felt no testicles in his scrotum. It’s possible he is acting like a male because one or both of his testicles remain hidden in his abdomen or inguinal area.

Even retained testicles produce testosterone that induces the tomcat behavior you describe plus big cheeks, thick skin that resists puncture wounds during fighting, and barbed spines on the penis.

During breeding, these barbed spines irritate the female cat’s vagina so much that her ovaries release eggs. Unlike female dogs that produce eggs whether they’re bred or not, female cats are “induced ovulators,” which means they release eggs only with vaginal stimulation.

Ask your veterinarian to examine Dusty’s penis for spines. If he has penile spines, then he has a testicle that’s producing testosterone.

An alternative is for your vet to measure the testosterone level in Dusty’s blood.

If Dusty has penile spines or a high testosterone level, then he will need exploratory surgery to find and remove his retained testicle(s).

Once they are gone, his nuisance behaviors should disappear.