A friend of mine at work recently lost his absolutely beautiful and much-loved pale orange kitten to an insidious disease that raises up a particular anger in me, probably because the virus has no known cure and it is therefore, in my estimation, cowardly and unfair and pretty scary.

I once lost a young cat to the same thing, and although it’s been nearly 30 years ago now, I still clearly remember coming home from work to find my little black-and-white Nikki staggering drunkenly from the living room closet, eyes unfocused and belly distended and rock-hard.

Some readers will now nod knowingly. Feline infectious peritonitis, or FIP, is something we can’t protect our cats from, and usually we can’t even successfully keep them comfortable for very long after it’s diagnosed. It is almost always fatal.

The disease begins as the feline enteric coronavirus, and veterinarians believe that about 30 percent to 40 percent of all cats have antibodies for the coronavirus in their systems. This number is considerably higher — closer to 90 percent — in catteries, where the felines share litter boxes and groom each other. The virus spreads by contact through secretions from infected cats.

In most cases, the virus will only show as sneezing, a runny nose or eyes, or perhaps a short bout of upper respiratory problems or intestinal disturbances. In these cases, the cat’s natural system is able to stave off further infections.

For reasons not yet understood, however — possibly a weakness in the way individual immune systems respond, possibly through a genetic mutation — the virus becomes clinical, or a full-blown case of FIP in a small percentage of cats. The virus uses the cat’s white blood cells to carry the virus through the body, usually congregating and causing an inflammation of the vessels in the brain or around the kidneys or abdomen. The body tries to fight back, but at this point it is overwhelmed, and the disease is nearly always fatal.

Young cats seem to be particularly susceptible to this disease, especially if they have already been infected with the feline leukemia virus, as my cat had been. Older cats, too, whose systems may already be weakened, also are more like to develop FIP. It can happen to felines of any age, though; the coronavirus is able to lie dormant in a cat’s system for years.

In addition, FIP develops in one of two forms: “dry” and “wet.” Symptoms of the dry form are slower to develop and are fairly general, making the disease hard to diagnose at first. Cats with this form usually lose their appetites and their energy and are generally depressed. Their coats become dry, and they may develop a fever that doesn’t respond to antibiotics.

The wet form takes its toll more quickly, expressing the same symptoms as the dry but also includes the characteristic swollen abdomen, which is an accumulation of the fluids in the vessels. Less commonly the swelling happens in the chest, but either way, the cat will quickly have a hard time breathing. This is followed by diarrhea or vomiting, and as the liver shuts down the urine will become dark.

Unfortunately for cat owners, we have no way to determine whether our cats will develop the fatal form of the disease. The ELISA test can tell whether our cats have been exposed to the coronavirus, but nothing is yet available to let us know whether it will change and progress.

As we think about our furry companions, we of course ask whether we can do anything to protect them from this virus, but in many animals it may be inevitable, coming from the mother or littermates. The best course of action is to keep litter boxes free of solid waste by cleaning them daily, and by disinfecting them regularly. Bleach is probably the safest alternative, and on hot sunny days I let mine dry in the back yard in the bright sunlight.

Another proactive measure that vets suggest is to keep new cats isolated from the others in your home, but given that the virus can remain dormant for such a long time, it’s not really feasible to do this. You would have to keep them separated literally for years.

It does help, however, if you keep your cats’ living environment clean, feed them healthy foods and make sure their vaccinations are current, so they don’t develop any illnesses that could weaken their immune systems and give the FIP virus that initial foothold.

Hardest of all is probably losing a cat to this disease and then feeling reluctant to get another for fear it might happen again. I’ve been in that position, but I’ve also learned that even the short time we’re given to spend together is never wasted and will always be cherished.

— Sue Novak is a board member for the Lawrence Humane Society.