Internal Parasites

Helping You Get the Most From Your Hunting Dogs

Internal Parasites

Roundworms, Whipworms, Hookworms and Tapeworms
There are many different internal parasites that may infest your dog. The most common are four parasitic worms that invade a canine’s gastrointestinal system (stomach, large and small intestine). They include roundworms (Toxocara canis and Toxiascaris leonina), whipworms (Trichuris vulpis), hookworms (Ancylostoma caninum, Ancylostoma brazilians and Uncinaria stenocephala) and tapeworms (Taenia). With the exception of tapeworms, most parasitic worms must be diagnosed by microscopic or laboratory examination of the dog’s stool. However, some of the larger roundworms and their eggs may be visible in the dog’s stool.

Roundworms invade the intestines of infected dogs. They deplete the dog of needed nutrients and may cause malnutrition and stunted growth in puppies. Roundworms can cause weakness, vomiting and diarrhea. Left untreated, roundworms can cause respiratory problems, blockages of the intestines and severe infections to the lungs and liver. Although roundworms can occur in dogs of any age, most puppies are born with roundworms and need to be dewormed regularly. Signs of roundworms also include a swollen abdomen ("potbelly") and a dull, scruffy look. Roundworms are usually acquired from contact with the soil.

Whipworms usually cause vomiting, bloody diarrhea, weight loss and anemia. Most puppies are born with whipworms. They are often difficult to detect or eradicate, as dogs pick them up from the soil and the eggs can survive in the ground for several years.

Hookworms attach themselves to the dog’s intestinal lining, causing internal bleeding. Hookworms feed by removing small pieces of tissue from the intestinal walls resulting in blood loss and inflammation. Hookworms are often passed on to puppies through their mother’s milk. Hookworms can cause anemia, weakness, malnutrition, diarrhea and weight loss. Other signs of hookworms include pale gums. Left untreated, they can cause death in puppies due to blood loss.

Tapeworms are usually visible on or in the stool and sometimes attached to the hairs surrounding the dog’s anus. Tapeworm segments are often described as looking like grains of rice. Tapeworms are acquired either from fleabites or from eating infected organs of dead birds or animals.

Symptoms of gastrointestinal parasitic worm infestation often include diarrhea, constipation and vomiting. Blood may be visible in the dog’s stool and the dog may become anemic. Other symptoms include weight loss, loss of conditioning and dry skin and hair. The dog may develop intestinal or bile duct blockages due to a massive presence of hookworms. If untreated, these blockages can lead to the canine’s death. The dog may also develop pneumonia or tissue damage due to roundworm larvae migrating into the animal’s lungs or other organs. Dogs can also develop dermatitis on the feet from migration of hookworm larvae. As with most illnesses, older dogs, previously ill dogs and puppies are more susceptible to gastrointestinal parasitic worms.

Once a veterinarian has determined that a dog is infected with a certain type of parasitic worms, a prescribed course of treatment can begin. Treatment quite often includes medications, injections and worming pastes, liquids or pills. Most common parasitic worms have a life cycle, which permits complete eradication by worming the dog twice over a two-week period. The first worming eliminates the adult worms. The second worming destroys any remaining worms that were subsequently hatched, thus preventing them from producing more parasitic worms.

Gastrointestinal parasitic worms may also be passed on to puppies through the uterus or via a nursing dam’s milk, therefore it is important to treat all nursing females concurrently with puppies.

Keeping your dog in good physical condition, providing proper nutrition and a sanitary environment can all help to keep your dog free of parasitic worms.

Deworming Guidelines:
  • Puppies: Begin treatments at 2 weeks and repeat at 3, 4, 6, 8 and 10 weeks of age.
  • Nursing Dams: Treat concurrently with puppies.
  • Adult Dogs: Treat regularly as a preventative (included with most of the better once-a- month Heartworm medications). Provide your veterinarian with a fresh stool sample for testing during regular semi-annual visits.
  • Newly Acquired Dogs: Obtain a deworming history if possible, treat as soon as possible followed by a second treatment two weeks after initial deworming.

    Heartworms (Dirofilaria immitis) are parasitic worms, which inhabit the heart muscle and lungs of infected dogs. Heartworm disease can cause serious health problems including death due to heart failure or pneumonia. Since it was first identified in certain regions of the country, the presence of heartworm has increased steadily and has now been identified in all 50 United States. The Heartworms lifecycle begins when a mosquito bites an infected animal. While drawing blood into its body, the mosquito also draws in immature heartworm larvae. The heartworm larvae continue to develop inside the mosquito for several weeks. The mosquito then bites an uninfected animal depositing the heartworm larvae on the animal’s skin. The larvae migrate through the animal’s skin and tissue into the bloodstream, where they continue to develop. Within six months, the maturing heartworms reach the heart and lungs causing disease to those muscles. The mature female heartworms produce eggs, which hatch in a few weeks into tiny larvae. The newly hatched larvae enter the bloodstream and circulate through the infected animal’s body, continuing to develop. Symptoms of heartworm disease in dogs include coughing, difficulty in breathing, depression, sluggishness and a reduced ability to exercise. Heartworm disease in dogs is 100% preventable. By following your veterinarian’s recommended monthly heartworm medication, the disease can be prevented in all cases. A heartworm test is often required if the dog has never been on heartworm medication, been off the medication for a period of time or is a newly required animal and no prior records are available.

    As with most diseases, prevention is the best defense. Regular visits to your veterinarian, monitoring your dog and educating yourself to the signs and symptoms of different internal parasites can all contribute to keeping your dog healthy.

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