Visiting Veterinarian : Fungus sneaks in
PS has always been a kitty prone to panic, so when in need of veterinary attention her owner has usually opted to have me make a house call to her rambling vintage Vineyard home. You know the kind...full of aged wood steeped in dust and history, quirky latches on the doors, frames that have settled over generations until there are no right angles and nothing closes all the way. On more than one occasion, PS has eluded my grasp, escaping to one of the infinite, inaccessible nooks and crannies in the house, so I understood Mom's reluctance to have unnecessary visits. "You know how much it stresses her," she said, calling to report a small mass on the cat's leg. "Do you think it's worth it for a little lump?"
"We really should check it out," I replied. "Just to be sure it's nothing worrisome, like cancer." Mom agreed to try to capture PS and confine her in a pet carrier in the kitchen so I could come later and take a peek.
When the time arrived, we lifted PS gingerly from the carrier and put her on the kitchen table, while Mom guarded the one door to the room that wouldn't quite close. "This mass isn't anywhere near where we give vaccinations," I said, palpating the lump. "So it's not injection-related fibrosarcoma, but I'm still concerned about the possibility of cancer."
We decided to take an aspirate for a histopathologic evaluation before proceeding with anything like surgery. "She's been sneezing a little, too," Mom added. I swung PS around and examined her face. No nasal or ocular discharge. Considering the slight mustiness of the old house, closed up tight against the winter cold, an occasional sneeze was not surprising. "I wouldn't worry about that, as long as she's feeling fine otherwise." I took the necessary samples and made slides. "We should have results soon," I said, packing my bags and heading out. Several days later, the pathologist faxed the report. It wasn't cancer. It was fungus.
Cryptococcus is a yeast-like fungus most commonly found in the droppings of birds, especially pigeons, in vegetation such as tree bark and decomposing leaves, and in soil. In a warm, humid environment, the organism can persist for years. There are many different subtypes, some more likely to produce disease than others. A wide variety of animals can be affected, including dogs, cats, horses, ferrets, goats, sheep, cattle, parrots, cockatoos, marine mammals, and people. The fungus usually enters the body via the nasal cavity, hence the typical presentation in cats is nasal discharge, stuffy nose, and sinus infections. Often when a cat is exposed, its immune system contains the infection locally, then fights it off completely and self-cures. But not always. Sometimes infection spreads, most commonly to the central nervous system and eyes. It may also disseminate to internal organs or skin, causing nodules like the one on our kitty's leg.
We visited PS in the kitchen again to do additional testing, checking for Feline Leukemia or Feline Immunodeficiency Virus, which may weaken the immune system. I sent out a Cryptococcus antigen titer which measures polysaccharides shed from the organism. This titer would not only confirm our diagnosis, but help us monitor response to treatment. "How's she feeling? Any more sneezing? " I asked, drawing the blood sample.
"She seems fine," Mom responded. I swung PS around to check her nose again. Whoa. Looky here. This is new. PS had a large soft swelling between her eyes.
"Well, this is consistent with systemic Cryptococcus," I said, showing the owner the fluctuant area.
"How did PS get this infection?" her owner asked. "She hasn't been outside in years." I admitted it was unusual. Cryptococcus is primarily a disease of outdoor animals. The best explanation my research had turned up was that contaminated material could be found in the soil of house plants, or brought inside on shoes or clothes, or inhaled after stirring up dust in areas where birds have been. "It's not directly contagious from cats to people," I added, "but be aware that the organism must be in your environment. I can't give human medical advice but let your doctor know about PS." People usually don't get sick with Cryptococcus, but rarely it can cause disease, especially in immuno-compromised individuals such as those with organ transplants, living with HIV, or undergoing chemotherapy. Symptoms include headaches, dizziness, sleepiness, and mental confusion.
"Let's start medication immediately," I advised, hoping PS would not be one of the 25 percent of feline cases in which the organism goes to the brain, causing blindness, ataxia, weakness, and seizures. Treatment involves administering one or more antifungal medications. We chose fluconazole, which is given orally, has minimal risk of side effects, and is reasonably economical.
"She's going to need two pills a day for many months, maybe even a year or more," I broke the bad news. "Crypto can be hard to cure and she can relapse, especially if we stop treatment too soon." I explained we would monitor antigen titers regularly, as well as liver function and clinical signs. At some point we might opt to surgically remove the leg nodule or drain the facial swelling. If she didn't respond to fluconazole, there were other antifungal we could try.
It may be a long time before we know the final outcome, and we may never know where PS picked up this infection. For now, mom is doing a stellar job of pill-popping. PS is responding nicely. And we've refined our cat-in-the-kitchen routine, so I can visit PS for follow-ups without playing hide-and-seek throughout the house.