CONTROLLING GASTROINTESTINAL HELMINTHS
Historically, efforts to control gastrointestinal helminths in dogs and cats have focused on early effective deworming of
pups and kittens. At present, the joint recommendations of the Centers for Disease Control and Prevention and the American
Association of Veterinary Parasitologists are that pups should be dewormed at 2, 4, 6, and 8 weeks of age with an anthelmintic
effective against both ascarids and hookworms, and that kittens, which do not become infected with gastrointestinal helminths
until after birth, should be dewormed at 3, 5, 7, and 9 weeks of age. Nursing dams should be dewormed along with their young.
All pets should begin receiving a monthly heartworm preventive that also controls intestinal parasites at the earliest age
possible (6 to 8 weeks), and they should undergo regular fecal examinations and receive treatment as needed.
Such an approach makes sense because younger animals consistently harbor larger numbers of parasites and pass more eggs in
their feces to contaminate the environment. However, pups and kittens often are not brought to a veterinarian until 6 or 8
weeks of age; by that time, the environment probably has been contaminated with ascarid and hookworm eggs. To dramatically
reduce infection of pups with ascarids and hookworms, dams can be treated late in pregnancy after the larvae have been activated
and, thus, are susceptible to anthelmintics.22 Regardless of the approach taken, every effort should be made to ensure that all pups and kittens are cleared of gastrointestinal
In recent years, many veterinary parasitologists and internists have begun to recommend that all dogs and cats be treated
for gastrointestinal parasites year-round. This approach may, at first, seem overly aggressive to veterinarians who are more
comfortable with simply performing annual fecal examinations and treating any parasite infections that are detected. Annual
fecal examinations followed by appropriate treatment are certainly an important part of veterinary preventive care. However,
waiting for an annual fecal examination to indicate that gastrointestinal parasites are present allows the environment to
become contaminated, sometimes over many months, with eggs that may then serve as a source of reinfection to that pet, other
animals, and people. Treating pets routinely year-round with ant helmintics effective against gastrointestinal parasites will
help eliminate patent gastrointestinal parasite infections and reduce environmental burdens of parasite stages infectious
to pets and people.
Several safe effective anthelmintics are available for use in a year-round program to control gastrointestinal parasite infections
in dogs and cats. Veterinarians are often comfortable with using heartworm preventives that are also effective against gastrointestinal
parasites because they already use these products in their practices. In the southeastern United States, where heartworm is
actively transmitted most of the year, many veterinarians already routinely prescribe year-round heartworm preventives that
are also effective against intestinal parasites. The seasonality of heartworm transmission in more temperate areas depends
on varying climatic factors, and the onset of mosquito activity is somewhat unpredictable. Considering how many pets travel
with their owners to heartworm-endemic areas and how frequently pets encounter infectious stages of intestinal parasites in
the environment, year-round administration of a heartworm preventive that also controls intestinal parasites may be warranted
throughout the United States.
None of the currently available combination heartworm and intestinal parasite control products is effective against cestodes.
To also eliminate infections with D. caninum and Taenia and Echinococcus species in dogs and cats, a product containing either praziquantel or epsiprantel must be used. Fenbendazole has efficacy
against Taenia species but not the more frequently encountered flea tapeworm D. caninum. In addition to anthelmintics, effective control of tapeworms also requires owners to stringently adhere to a veterinarian-prescribed
flea control program to eliminate reinfection with D. caninum and to prevent their pets from roaming and consuming prey to avoid reinfection with Taenia and Echinococcus species. Keeping dogs in a fenced yard or on a leash, keeping cats indoors, and feeding pets only cooked canned or dry commercial
food are all excellent means of preventing parasitic infection.
Susan E. Little, DVM, PhD, DEVPC
Department of Infectious Diseases
College of Veterinary Medicine
University of Georgia
Athens, GA 30602