Dogs are prone to numerous types of parasites, both internal and external. Internal parasites include: Roundworm, whipworm, hookworm, tapeworm, heartworm, coccidia, giardia and many others. Every six months, a fecal sample should be brought to your vet. He can test the fecal matter for the presence of eggs which are passed in the dog's stool. This can detect the presence of all the above except tapeworm and heartworm. Tapeworms are detected by the presence of tape segments passed in the feces which look like grains of rice and may be moving. Heartworm requires a blood test. This blood test should be administered once a year in the spring BEFORE the dog is put on the heartworm preventative. Severe infestations of most worms can cause diarrhea, suppressed appetite and a general decline in health. Noting a dry, coarse coat, or one in which the topcoat (the long, straight, darker hairs) on the dog's back pulls out easily is often an early sign of worms. Worms can also be aggravated by physical or emotional stress. If the vet notices eggs, he will prescribe the proper medication for the particular type of worm involved. A single "negative" fecal test is sometimes not sufficient to determine that no worms exist. It is sometimes necessary to repeat the test if no other causes can be found for the dog's distress.

Prevention of internal parasites is by cleaning up your dog's stools immediately so that he will not re-infect himself and not allowing him to sniff at other dog's stools. The adult worms in a dog lay eggs in the stool. After about three days, the stools dry out and the eggs are carried by air to a dog's lungs. There they hatch into larvae which travel to the dog's intestines where they mature into adults. Here they rob nutrition from the dog and some worms burrow into or attach to the lining of the intestine. This damages the intestine and can cause bleeding. Most wormers only work on the adult worms, not on eggs or larvae. Thus, usually two wormings are given: One to kill the adults the dog has now. One to kill the larvae after they turn into adults but before they start laying new eggs.

Tapeworms require an intermediate host to carry young worms from the feces to the dog. A dog cannot get them directly from another dog. The most common host is the flea. If a dog has had fleas, he may well also have tapeworms.

Heartworms are passed by mosquitoes which become infected after biting an infected dog. They then pass the "microfilaria" of the heartworm when they bite another dog.

External parasites include: Fleas, ticks, scabies, demodex mites and others.

Fleas can be found by examining the dog's stomach where the coat is thinnest. Any dirt that "walks" is likely to be a flea. Their bodies are flattened and they have extremely hard shells. The only way to crush them is with your thumbnail. If you spot some gritty dirt near the dog's skin do the following: Take some of the dirt and place it on a wet paper towel. After a few seconds, smear the dirt across the towel. If it leaves a reddish-brown streak, it is flea dirt. The color is from digested blood. Excessive scratching is also a good reason to look for fleas. Fleas on your dog can be eliminated with either a regular bath (lather the dog and leave lathered for 5 minutes) or with topical flea and tick products. We personally prefer to limit the chemicals that our dogs are exposed to. However, it does no good to treat the dog without treating his environment since the flea spends only ten percent of its time on the dog. The rest of the time is spent in the rugs, in the dog's bedding or in your bedding. Thus, wherever the dog spends its time must be treated with a powder or spray. Also treat your sheets since the fleas may find you more palatable then the dog after he has been sprayed or powdered. Do not mix different types of flea sprays within a few days of each other unless they use the same type of insecticide since some combinations could injure the dog. Apply all flea and tick products according to the package instructions as they can be toxic to your pet.

Ticks are small, round insects which bury their heads into the dog's skin to drink the dog's blood. After a few days, they will go from small and round to large and round as they inflate with blood. They are often found around the eyes, on the ears, between the shoulders and in the armpits. They produce no itching. The best way to find them is to give the dog a thorough petting and carefully examine any small bumps you may find. If the bump is attached at one end and has legs, it's a tick. The dog will also think that this examination is a great idea. Ticks are also very difficult to crush. They are not hard, but they have an extremely tough skin. Tick sprays are of limited effectiveness. An infested dog should be given a tick dip by the vet or a professional groomer. Individual ticks can be removed by coating them with Vaseline or other oil, then pulling them off a couple of hours later. The oil clogs their pores and they suffocate. They can also be removed with a pair of pointed tweezers. Grasp the tick right at the skin and pull slowly and firmly. Do not grasp the tick's body or it can inject material back into the dog like a hypodermic syringe. Be careful to try to get the tiny head when you remove the tick. If it does not come out, it could become infected. A live tick holds on so tightly that its head will pull off before it lets go of the dog. If you have been in the woods with the dog and find ticks, it is also a good idea to check yourselves since the ticks are not too particular about who their hosts are.

Lyme's disease is carried by the deer tick and can infect both dogs and people. This disease is showing alarming increases in this area. Other than avoiding ticks, the best prevention is to remove them as soon as possible since they do not infect their host immediately. If you notice a red, splotchy rash around a tick bite area report to either the Vet or to your doctor as applicable. Later symptoms of Lyme's disease are joint stiffness and lameness which could develop into arthritis if untreated.