Which Worms Why - A quick guide to parasitic worms that pose the greatest threats to pets and people.

How do pets get heartworm disease?
What should you do if your dog gets heartworm disease?
How do dogs get hookworms?
What should I do if my dog has hookworms?
How do dogs get roundworms?
What should I do if my dog has roundworms?
How do dogs get whipworms?
What should I do if my dog has whipworms?
Which parasitic worms are the most common?
What is a great way to treat and control intestinal parasitic worms in my dog?

How do pets get heartworm disease?
When an infective mosquito bites a dog, tiny immature heartworms, called larvae, are deposited on the animal's skin. The larvae find their way through the bite wound and into the dog's tissue. Then, unless they are eliminated by a heartworm preventive, they migrate through the body, developing as they go, and eventually arrive in the heart and lungs. Full-grown heartworms can cause discomfort and debilitation, and may even lead to death.

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What should you do if your dog gets heartworm disease?
Treating heartworm disease in dogs is a difficult and expensive course of action. The dog must endure a series of arsenic-based shots and be kept in a subdued state that protects the animal from overexertion. This can mean crating the animal, sometimes for weeks at a time.

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How do dogs get hookworms?
Hookworms are typically transmitted to puppies when they consume the milk of an infected mother. Hookworm larvae can also penetrate the skin of animals and people directly when they walk bare-footed through contaminated areas.

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What should I do if my dog has hookworms?
See your veterinarian promptly, as hookworm infections can be lethal, especially to puppies and young dogs. Your veterinarian will administer a dewormer.

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How do dogs get roundworms?
Roundworms are generally transmitted to puppies from their mothers prior to or shortly after birth, or in her milk. They can also enter their hosts, including humans, through contact with soil, sand, plants, or objects like toys or gardening and sporting equipment contaminated by the feces of an infected animal.

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What should I do if my dog has roundworms?
Your veterinarian will dispense a medication that will deworm the animal. It may take more than one round of deworming to get rid of the adult worms and existing immature roundworm life stages (eggs and larvae).

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How do dogs get whipworms?
The only way for a dog to get whipworms is by accidentally eating whipworm eggs that may be embedded in feces, soil or even on the rim of a water dish.

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What should I do if my dog has whipworms?
A veterinarian will provide a dewormer to kill the existing whipworms in your dog.

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Which parasitic worms are the most common?
Roundworms and hookworms are the most common intestinal parasites of dogs.5 Given the dire consequences of heartworm disease and the ease with which it can be prevented, heartworms are surprisingly common, as well.1

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What is a great way to treat and control intestinal parasitic worms in my dog?
Ask your veterinarian for the heartworm preventive that treats and controls the most common and significant intestinal parasites.

Keep your dog's environment as clean and clear of feces-contaminated soil and items as possible—and be sure to take your dog to your veterinarian for an annual exam.

Make sure that your heartworm preventive of choice treats and controls multiple species of hookworms and roundworms.

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1Heartworms in Dogs. Available at: www.petsandparasites.org/dog-owners/heartworms.html. Accessed on December 14, 2009.

5Little SE, Johnson EM, Lewis D, et al. Prevalence of intestinal parasites in pet dogs in the United States. Veterinary Parasitology 2009;166:144–152.