How to Control Parasites in Your Dog

Fleas, ticks, heartworms and intestinal worms – for their small size, these parasites pack a lot of misery for you and your pet. Besides driving your faithful companion crazy, they pose a hazard to pets and people.

Fortunately, you’re not without the means to fight back. What follows are guidelines and recommendations to keep your household safe and happy.

Know the Enemy

The first thing is to know what you’re up against:

• **Intestinal Parasites.**Dogs are victims of several internal parasites including roundworms, coccidia, giardia, hookworms and whipworms and can cause nausea, vomiting, diarrhea and anemia. The most common are roundworms (ascarids) that infest nearly every puppy at some time in his life. Usually they are born with them; they are passed from mother to young.
• Tapeworms can be a big problem when flea infestation is high. Adult dogs typically acquire worms when they lick up microscopic eggs that are ever-present in contaminated soil or grass, or they swallow a flea. Mature dogs usually develop a resistance to most intestinal parasites, but the whipworm (Trichuris vulpis) can still cause problems, leading to colitis (inflammation of the colon) and weight loss.
• Evidence of roundworms and tapeworms can be seen without the aid of a microscope, but other worms are not so easily diagnosed. Early diagnosis is important because all worms do not respond to the same treatment.
• For information on illness caused by these internal creatures, click on Intestinal Parasites and Protozoan Parasites.
• **Fleas.**Watching a flea-bitten pet scratch herself desperately is a heart-rending sight. Fleas are a common problem for dogs, cats and people, who can also be bitten. As if the bite wasn’t bad enough, many dogs are allergic to fleas.
• When a flea bites your dog, it injects a small amount of saliva into the skin to prevent blood coagulation. Some animals may have fleas without showing discomfort, but an unfortunate number of dogs become sensitized to this saliva. In highly allergic animals, the bite of a single flea can cause severe itching and scratching. Fleas cause the most common skin disease of dogs – Flea Allergy Dermatitis. Other concerns regarding fleas can be found in the article The Dangers of Fleas in Dogs.
• **Ticks.**These creatures present another set of problems. When ticks are in need of a blood meal, they seek out prey by heat sensors. When a warm object passes by them, they attach themselves by clinging to clothing or fur or falling from trees onto the object and insert pincher-like mouthparts into the skin and begin feeding. These mouthparts are locked in place and will only dislodge when the tick has completed the meal. Once the meal is complete, the adult female falls from the prey and seeks shelter. Eggs are born and the adult female dies.
• Dogs are a common target for ticks. If you live in an area populated with ticks you should keep a sharp eye on these parasites. They can transmit serious diseases (such as rickettsial diseases like Rocky Mountain spotted fever and ehrlichiosis) to dogs and even to humans. Find out more by reading The Dangers of Ticks in Dogs.
• **Heartworms.**Heartworms have the potential to cause serious illness. All it takes is one bite from a mosquito carrying a heartworm larva. In time, the larva develops into a full-fledged adult worm, finding a home in the arteries of the lungs. Without treatment, dogs with heartworm disease will become lethargic, lose their appetite and begin to have difficulty breathing. Heart failure can also occur. For more information, read Canine Heartworm Disease.

The Battle Plan

• **Preventing Intestinal Parasites.**Puppies are regularly dewormed for roundworms and hookworms at the time of their “puppy shots.” If your puppy hasn’t been dewormed, talk to your veterinarian about getting this important step taken care of. A stool sample should be collected prior to each puppy vaccination visit, and a follow up sample examined at the appropriate interval after the last deworming medication has been given.
• Worms can affect mature dogs as well. A yearly fecal exam is recommended for most adult dogs unless the dog is taking a heartworm preventative that also controls intestinal parasites. With primarily outdoor dogs, it may be beneficial to evaluate stool samples two or three times a year if the risk of infection is high. Or you may decide to administer a heartworm preventative that also controls intestinal parasites. Some of the newer heartworm combinations fight all three threats: heartworms, intestinal parasites and fleas.
• **Fighting Fleas and Ticks.**Even minor flea bites can cause severe reactions in some pets. Though the itching component to flea-allergy can be treated with antihistamines or even corticosteriods (prescribed by your veterinarian), the best approach is to kill the flea and prevent its return. There are many products available to treat flea infestations. Some of the over-the-counter powders, sprays and collars (such as those from Hartz® or Sergeants®) contain permethrin, which is moderately effective.
• However, the best flea products are prescription – see your veterinarian for these. Products such as Program® (lufenuron) and Sentinel® (which also prevents heartworm disease) prevent development of fleas that attack your dog. If your dog already has fleas, then you need to kill them first with a product like Capstar® brand of nitenpyram, Frontline® brand of fipronil or Advantage® brand of imidacloprid. Some of these have residual effects that can also control ticks. A new product, Revolution®, is a topical treatment to prevent external parasites, heartworm and intestinal parasites. In addition to these prescription products, a collar tag called Preventic® is also effective in controlling ticks on some dogs. Other ideas can be found in Flea Control and Prevention.
• In tough cases, you may have to wage all-out war to conquer fleas. This means a comprehensive flea control program, requiring treatment of the pet, the pet’s bed, the yard and the house. A variety of sprays, dips, powders, foams and oral products may be recommended.
• Ticks are very difficult to control, but a program of tick prevention and meticulously combing and grooming your dog can keep them at bay.
• **Preventing Heartworm Disease.**Preventing heartworm disease is easier and much preferred to treating an active heartworm infection. Treatment is easy – just one tablet once a month. See Heartworm Prevention Guidelines for Dogs.
• Not all parasitic diseases can be prevented but many can be treated. Mites are parasites that can cause serious illness in your dog. For more information, see Ear Mites in Dogs, Sarcoptic Mange, Demodicosis and Cheyletiellosis.