Her beloved kitty appeared to suffer seizures

Subtle and sometimes even sly, cats are masters at keeping humans guessing.

So when Chicopee the Siamese cat started to have strange "episodes," his owner thought she was imagining things.

"He would sort of pause, look a little stunned, and then start to wobble," said Judy Schachner.

After three such events in one week, the Swarthmore woman took her 6-year-old seal point to the vet.

Chicopee had lost some weight and his skin seemed loose. His right eardrum bulged slightly. His exam, including heart sounds, was otherwise unremarkable.

Except for mildly elevated liver enzymes, Chicopee's blood work was normal, as was his urinalysis. His feline leukemia (FeLV) and feline immunodeficiency virus (FIV) tests came back negative.

Though Chicopee displayed no neurologic deficits in the office, his veterinarian, Andrea Lerner of Just for Cats in Folsom, attributed the episodes to balance issues. Middle-ear infections can impair balance. Because Chicopee's right eardrum appeared inflamed, Lerner put the cat on antibiotics for a week. But his mysterious episodes increased in frequency and severity.

"He would fall with his legs splayed out. He rolled down stairs. He even tumbled off my work table," said Schachner, author and illustrator of the Skippyjon Jones children's book series.

Though he never lost consciousness during the episodes, he started drooling.

Was Chicopee having seizures? Lerner wondered. Or were his problems truly related to ear infections - or even a polyp?

Lerner recommended skull X-rays to further evaluate the ear canals, but his owners declined. Then came an alarming cluster of episodes.

Lerner tested Chicopee for toxoplasmosis and feline infectious peritonitis (FIP), which can cause neurologic problems in cats. Both tests were negative.

Could Chicopee have a liver shunt? They trap toxins in the bloodstream, which can cause neurologic problems. His liver enzymes had been elevated but further blood tests ruled out a shunt.

Lerner next sent Chicopee to a neurologist, who reported a normal exam, except for one wobbling episode in the office, as well as dilated pupils that exhibited delayed response to light. Based on Chicopee's history, he suspected possible brain-stem dysfunction with associated epilepsy.

Thiamine deficiency can be the cause, so he put Chicopee on a trial course of thiamine, plus Valium to control seizures.

To no avail. Lerner next recommended a cardiac evaluation.

Chicopee had severe hypertrophic cardiomyopathy (HCM). The condition, characterized by thickening of the heart muscle, impairs cardiac function and can be deadly.

The most common heart disease in cats, HCM also strikes dogs and people. Cats of any age can be experience HCM, but are usually diagnosed at 5 to 7 years; males are more commonly afflicted. HCM sometimes runs in families, including certain lines of Maine coon and sphynx cats.

HCM produces robust heart walls that pressurize the chambers and restrict their proper filling with blood. Hypertension may result, in some cases leading to fluid buildup in and around the lungs. Arrhythmias can also develop.

In addition to having poorly oxygenated blood (hypoxemia), kitty is now at risk for stroke: The blood that pools in the hypertrophic heart stagnates and sometimes clots. These clots can escape into vessels feeding key areas like the brain and hind legs, sometimes causing sudden paralysis.

Chicopee's balance issues likely resulted from weakness due to his heart disease rather than from nerve dysfunction.

During his cardiac exam - which revealed a severe arrhythmia and a newly developed heart murmur - Chicopee's gums turned purple several times.

In addition to thickened heart muscle, Chicopee's echocardiogram showed sludgy material in a couple of chambers - most likely clots.

"At any moment, that cat is at risk for throwing a clot and becoming history," Lerner said.

Chicopee is now on lifelong aspirin and Plavix to thwart clot formation. He is eating better, has regained lost weight and seems to be enjoying life.

He still has up to 10 hypoxemic events a day. But Schachner says Chicopee knows his limits: He often waits to be carried upstairs.

At a recent exam, Lerner noticed every time someone approached Chicopee, his front end would sink down and his tongue would turn blue. Though she would like to monitor his heart rate and blood pressure regularly, Lerner has recommended keeping veterinary visits to a minimum.

When he was diagnosed, Chicopee was given just months to live. Now, more than a year later, Schachner is philosophical about the cat she has raised since he was just a few months old.

"He's outlived his expiration date," she said. "So I consider every day with him to be lucky."