A common question from clients acquiring a new kitten is, "How do I tell if it is a male or a female?" Due to the unique anatomy of a kitten, this is challenging. In female kittens the anal opening is just above the vulva and is sometimes described as a dot closely followed by a slit (a semicolon). In male kittens the anus is just above the hair-covered scrotum which is followed by the prepuce containing the opening for the penis. This is sometimes described as two dots (a colon). When multiple kittens are present, a comparison of the anatomy will frequently answer the question. When the kitten arrives at the clinic for their first vaccinations at eight weeks-of- age the veterinarian will confirm the sex of the kitten.

The one on the right is a male; the one on the left, his sister.
Photo borrowed from Beautiful Cats by Howard Loxton.
Click image to enlarge
 

As the kitten grows up, it becomes easier to tell boys from girls. Males have broader faces, are generally larger and will average about two pounds heavier than their sisters. By the time they are six months old the testicles are very apparent in the scrotal sac. Both sexes should be neutered by the time they are six months of age to prevent unwanted kittens and to avoid some behavioral problems. Un-neutered male cats (toms) produce very strong smelling urine. To identify points important to them, tomcats spray small amounts of urine on vertical surfaces. The urine of females and neutered males does not have the potent odor of that of tomcats. About 5% of neutered females and 10% of neutered males will engage in marking behavior at some time in their life. Female kittens usually experience their first heat cycle when they are between five and seven months old. Queens (female cats) in heat may vocalize (often continuously), roll on the floor and show posture changes that include kneading with their feet. They may also engage in urine spraying during this time.

Clients frequently ask if a male or female cat is a better companion. Although many people have strong opinions on both sides, there is minimal research to support either position. At The Cat Clinic, we see a diverse group of patients, both male and female, and sex does not seem to be correlated to how well they blend into their families. Both males and females make excellent companions.