Internal Parasites, Roundworms, Hookworms, Whipworms, Tapeworms, Coccidia and Giardia.

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Internal Parasites

Unlike external parasites, internal ones can cause severe disease and even death if left untreated. Imagine dozens of spaghetti-sized worms that are clogging up your heart valves, as is the case in canine heartworm disease. That's how dangerous some of these internal parasites can be. Puppies are particularly susceptible to internal parasitism. In fact, many of the intestinal worms of puppies are transferred from the mother.

The most common internal parasites in dogs are roundworms, hookworms and whipworms. Reports suggest that more than 80 percent of all puppies will be born with, or quickly acquire, roundworms. These parasites live in the intestines and drain vital nutrients that growing puppies need. On rare occasions a puppy will vomit up roundworms, but worms are normally diagnosed when your veterinarian checks a fecal sample. Whipworms do not pass as many eggs as roundworms or hookworms, so repeated fecal checks may be necessary. Your veterinarian may elect to treat for them anyway based on clinical signs. Picking up after your dog is very important to reduce the chances of internal parasites being spread.


Roundworms are spaghetti-like worms that can cause a potbellied appearance and dull coat, along with more severe symptoms, such as vomiting, diarrhea and coughing. Puppies can acquire these in utero and through nursing. Both hookworms and roundworms m also be acquired through ingestion.


Hookworms are almost microscopic intestinal worms that can cause anemia, which could lead to serious problems, including death, in young puppies. If their mother has them, the puppies may be born with them, or they can be transmitted to humans through penetration of the skin.


Luckily whipworms are not as prevalent as roundworms or hookworms. These are small intestinal parasites with a whiplike, Tapering tail. The eggs need to be ingested to complete their life cycle, but they can survive in the ground for long periods of time. Whipworms cause diarrhea, often with mucus and blood. Dogs with whipworms may defecate frequently and strain to do so. A large number of whipworms can be a serious drain on an adult dog, let alone a puppy. Whipworms are resistant to treatment, so repeated treatments may be necessary. It is also important to clean up the environment, or your dog can easily become reinfected. Cement runs may be bleached, while dirt runs may need to be dug up and replaced with fresh soil.


Tapeworms are long, flat, ribbon-like, and segmented. Dogs can acquire tapeworms in two ways: by ingesting the flea through licking and chewing, or through rabbits, rodents, and certain large game animals that serve as intermediate hosts for other species of tapeworms. If your puppy eats one of these infected hosts, she can acquire tapeworms.

Coccidia and Giardia

Coccidia are well-known intestinal protozoa that can infect dogs. There are many species, but virtually all work the same way. Dogs that live in a less-than-clean environment, especially puppies, may ingest cysts through contaminated food or fecal material. Giardia is sometimes called beaver fever, but beavers shouldn't bear the blame for this one. This protozoal parasite is quite hardy and can exist for long periods of time in a wet environment.

Protozoan infections, coccidia and giardia usually affect puppies, especially where large numbers of puppies are brought together. Symptoms include diarrhea, weight loss, and lack of appetite. These infections are not always apparent upon fecal examination.