Watch out for higher levels of testosterone in cats
By Michelle Posge, DVM
Friday, June 26, 2009
Published in the "Your Pet" column of The Nashua Telegraph.
The column runs on the second and fourth Fridays of each month.
A popular National Public Radio show called "This American Life" aired a piece last year about the male hormone testosterone. To make things interesting, the staff decided to test their individual testosterone levels and attempt to predict on air who would have the highest levels based on their behavior traits. As it turned out, the winner was, unexpectedly, a homosexual man – a Martha Stewart fan, no less.
It seems that – in humans, at least – preconceived notions of masculinity as it pertains to testosterone don't always hold up. If this gives you doubts about the validity of hormone-influenced behavior in pets, there is a cat you should know about.
In the Journal of the American Veterinary Medical Association, Dr. Ralph Millard and his colleagues published a case study about a 13-year-old household cat that experienced a dramatic change in personality. It was the type of change that might make one think of a brain tumor.
This formerly well-behaved cat developed aggression to the owner and a tendency to spray strong-smelling urine around the house. Aggression and urine marking are behaviors associated with testosterone and are commonly seen in adult male cats that have not been neutered. But this cat was, in fact, neutered as a kitten despite tom-like behavior.
The veterinarian examining the cat found physical changes to go along with the behavioral transformation: thickened skin, enlarged facial muscles and a coarse hair coat. This is not expected in a neutered male cat, who should have low levels of testosterone.
As it turns out, this cat did have a tumor, but not in the brain. A growth was found in the adrenal gland, a hormone-producing organ next to the kidney, which was the source of abnormally elevated levels of testosterone. The tumor was surgically removed, and within eight weeks, the cat was no longer spraying and was affectionate toward the owner again.
So what makes a cat act male or female? Is it the brain or the hormones? The answer is both. There is a complex interrelation between the brain and hormones. The connection starts during the late stages of brain development. A surge of testosterone occurs in male kittens, thereby priming the brain for male hormones later in life. Without this male "brainwashing," the brain responds primarily to female hormones. The masculinization of the brain is what makes a cat neurologically male.
So even when a cat is neutered, he still has a male brain, ready to respond to testosterone from any source, even a adrenal gland tumor. According to Dr. Bonnie Beaver's book "Feline Behavior: A Guide for Veterinarians," 10 percent of neutered cats will behave like a tomcat even without high levels of testosterone in their system. This could be that the male behaviors are learned or are provoked by intense environmental situations and not always driven by testosterone.
What is intriguing about this case study is the demonstration of the power of hormones to cause a change in behavior. It is a good argument for neutering your cat, especially if you want a friendly pet that uses the littler box.
On a closer look, the case study is also a good example of how pet behavior problems can be caused by disease. It seems like it would have been easy for the pet owner in this case to focus on the problematic behavior, maybe even give up on the cat without thinking there could be a cure. By seeing a veterinarian, however, physical changes were identified, and the medical problem was diagnosed, thus making argument in favor of veterinarian involvement in addressing unwanted and problematic behavior.
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