Like the infectious diseases that are avoided by proper vaccinations, worms (intestinal parasites) are another potentially deadly enemy of your puppy's health easily prevented by proper care, hygiene, and attention.

Several types of worms infect dogs; tapeworms, whipworms, round-worms, hookworms, and heartworms are the most common.

Puppies and adult dogs become infected by worms by contact with contaminated soil; raw, contaminated meat (like a dead animal in the woods); or ingestion of an infected host (like a flea). That's why it's so important to clean up after your dog in the yard and around the house, and to have fecal exams performed by the veterinarian regularly (microscopic examination is often the only way to detect the presence of internal parasites).

You might suspect your puppy or dog has worms if his appetite decreases, he has an upset stomach, he loses weight, and you see blood or mucus in his stools. These symptoms are characteristic of an advanced state of parasitic infection; a dog can have a slight infection and appear normal until your veterinarian detects worms in his feces. For common infestations, safe, effective, and fast-acting worming medications are available.

Heartworm

The heartworm is a particularly deadly parasite because it infests and grows in the canine heart. Left untreated, heartworms literally strangle the heart, causing it to fail and the dog to die.

Heartworm is transmitted by infected mosquitoes. When they land on a dog to bite, heartworm larvae are deposited on the skin. The larvae burrow their way through the dog's skin, growing into small worms as they go. When they finally reach a blood vein, the worms travel to the heart, where they mature. Heartworms can grow four to twelve inches long, and a dog can be infected for years before symptoms are noticeable. A dog diagnosed with heartworm is in trouble either way. Treatment is intense and can even cause the inevitable death it seeks to avoid.

Today's dog owners are extremely fortunate to have heartworm preventive medication readily available. In some parts of the country veterinarians suggest giving dogs the preventive daily or monthly (depending on the type) only in seasons in which the mosquito is most active; in other parts of the country, veterinarians keep dogs on the preventive all year round as a safety precaution. Ask your veterinarian what's best for your dog and stick with the program. If you take your dog off preventive medicine for more than several months, he must be tested for the presence of heartworm before being allowed to go back on it.