A: Heartworm is a parasitic disease that has an affinity for certain climates. Anywhere that mosquitoes live can be a haven for this very serious condition.

The culprit is a worm, more than 10 inches long, that lives in the heart of its victim and causes heart failure. It reproduces by releasing into the bloodstream microscopically small larvae that can be picked up by a mosquito bite. Mosquitoes literally draw one of these small larvae up from one victim and transmit it to another, just by feeding. It takes about 6 months for this immature worm to develop into its adult size.

Mosquito bites are the only way that this "bad guy" parasite can be spread, so regions where there are lots of mosquitoes potentially have problems with heartworm disease. This is, indeed, the case in Lousiana and all of the Deep South, as well as other parts of the country where mosquitoes reside.

Even our Golden State has regional pockets where heartworm disease is endemic. The Sierra Nevada and its foothills, the Sacramento River Delta and even Lake Berryessa are a few of our problematic areas.

We don't see a lot of heartworm in most of south Santa Clara County or in San Benito County. But we do have areas with mosquitoes in the hills around Madonna ridge and in parts of the Uvas canyon. These regions have a real problem with this disease.

The Santa Cruz mountains are even worse. With their cool and moist environment, areas like Loch Lomond and Boulder Creek are havens for mosquitoes and heartworm. And it's important to remember that if a dog is bitten by just one infected mosquito, he may come down with this condition. So, if you ever take your dog to go hiking or to visit a friend in one of these areas, there could be that risk.

Heartworm affects dogs mostly, but occasionally it's seen in cats. It's easily prevented with a monthly oral medication that's safe and effective. The Katrina dogs that have this disease probably didn't get this medication and now will face a treatment regime before they can become healthy and adopted.

If you have a dog, and you take him or her with you to an area that may have mosquitoes, you really should give the once-a-month pill to prevent heartworm disease. It's safe, easy and effective.

Q: We just took our poodle, Jack, in for a checkup. He's drinking a lot of water and losing weight, so we thought diabetes, right? Wrong. The vet said he might have something called Cushing's and needs some tests that are very involved (read this as "expensive"). Is this a common problem in other dogs? Is it treatable? We don't know what to do.

A: Cushing's disease is more common than many people think, and the symptoms are very similar to diabetes. It occurs in both animals and humans, and is characterized by an overproduction of the hormone, cortisol, from the adrenal glands.

Cortisol is a naturally produced steroid that's necessary for normal metabolic function. The adrenal glands located near the kidneys secrete this hormone on demand. In other words, when it's needed, they deliver. And they get their "signal" to produce this substance from another gland, the pituitary, located at the base of the brain. The pituitary sees how much cortisol is needed and tells the adrenals to produce it. It's a rather complicated system, but it normally works very well.

However, if either of the adrenals or the pituitary gland develops a tumor (a growth), then the system starts to have trouble. Tumors are made of mutant cells that have a very rapid metabolism. Whatever they do, they do it faster than normal tissue. Pituitary and adrenal tumors secrete large amounts of their respective hormones regardless of metabolic need. In so doing, they drastically alter the body's metabolism.

Jack may be drinking lots of water because of high cortisol levels in his bloodstream. Steroids cause increased thirst. They also cause muscle to break down, which leads to weight loss. Chances are, Jack's tummy (his abdomen) is starting to look a little distended because of muscle wasting. He may also have lost enough muscle across his backline that you can feel the tips of his backbones easier than before. With untreated Cushing's disease, muscle loss is inevitable.

Some patients start to develop a thin hair coat, and many have a voracious appetite, yet still lose weight. Other, more subtle clinical changes also occur in dogs with this disease. In advanced stages, small hard plaques develop on the skin in a condition called calcinosis cutis.

There's also another form of this disease, called iatrogenic Cushing's. Here, the clinical symptoms are the same, but they occur as a reaction to steroid medication. Many years ago, dogs with flea allergies would be treated regularly with steroids to eliminate their itch. We know now that these medications (prednisone is one example) can cause Cushing's disease if used indiscriminately for long periods of time. If Jack has been taking any of these meds, be sure you talk to his veterinarian about alternatives.

Certainly there are other illnesses that could cause Jack's symptoms. Many of them are difficult to treat or manage. But Cushing's is the most probable here. The good news is that most Cushing's cases are treatable, though with time (a few years in some cases), treatment becomes less effective.

Diagnosis can be a little complicated. Sometimes only one blood test is needed. But because of the complexity of the disease (the different forms it can take), the diagnosis can occasionally be difficult to pinpoint without several different blood tests and even an abdominal ultrasound. Depending on the number of tests needed, the costs can vary from more than $100 to considerably more. Good medical care can be costly. Fortunately, the cost of treatment isn't prohibitive.

I hope Jack's condition is easy to diagnose, he responds to treatment and he thrives again. Good luck.

POST A COMMENT

If you are under 13 years of age you may read this message board, but you may not participate. Here are the full legal terms you agree to by using this comment form.