Like the infectious diseases that are easily avoided by proper vaccinations, worms are another potentially deadly enemy of your dog's health that are easily avoided and treated with proper care, hygiene, and attention. There are several types of worms that infect dogs. Tapeworms, whipworms, roundworms, and heartworms are the most common.

Dogs become infected by worms through contact with contaminated soil; raw, contaminated meat (such as a dead animal in the woods); or ingestion of an infected host (such as 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; dogs 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.

Besides avoiding places where your dog or puppy may become infested with worms and being alert to the signs of a potential infestation, you can further help your friend by feeding him a high-quality diet so that his system can naturally fight off any of these pests as effectively as possible. This doesn't mean that a diagnosed infection shouldn't be treated with traditional medications as prescribed by your veterinarian; rather, it means that there are foods that will naturally help your dog stay worm-free.

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 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 of the preventive for more than several months, she must be tested for the presence of heartworm before being allowed to go back on it.

Tapeworm

Tapeworms can actually be seen upon close examination of an infected dog's feces; sometimes they are visible around the dog's anus, as well. That's because tapeworms are long, segmented worms. They can grow to twenty inches, and the segments reproduce at the front of the worm and are cast off at the back. Castoff segments are the ones that are released by a dog when he defecates. Tapeworms attach and feed in the small intestine. They are transmitted by fleas, so when a dog licks or bites off a flea, it might contain the tapeworm larvae.

Fortunately, a tapeworm infestation is easily treated, though if the problem may have started because of the presence of fleas, it can easily recur if the flea problem isn't handled as well.

Roundworm

Roundworms can be found in the soil and in other infected animals. Dogs can get them by simply walking in infected dirt, or even nursing from an infected mother. Once in a dog's system, the roundworm can remain encysted for years, which is why even healthy mother dogs can end up passing the worms on to their pups. When the worms get active again, they move to the lungs where they develop into a larval stage. They get coughed up, and upon being swallowed, find their way to the intestines where they mature and reproduce. They can grow up to seven inches, and an infestation can clog the intestines. Affected dogs vomit and have diarrhea. It can take several rounds of medication to rid an infected dog of the worms.

Whipworm

This worm also thrives in the dog's intestine. It gets its name from its whip-like appearance, and these long worms can quickly form a mass that will easily obstruct the large intestine, causing bloody diarrhea and a very sick dog. Repeated treatments are usually necessary before a dog is free of these pests.

In sum, be forewarned that internal and external pests can make your dog seriously ill and potentially lead to death. Use common sense when you're out with your dog. Avoid areas that appear to be heavily trafficked by other animals or in which many strange dogs urinate and defecate. Keep your home and yard as clean as possible. Wash your dog's bedding. Groom him regularly and be on the lookout for fleas and ticks. These critters can be largely avoided if you're clean and conscientious.