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Ascarids and Hookworms
Ascarids (Toxocara canis, T. cati) and hookworms (Ancylostoma spp.) are common intestinal parasites of dogs and cats (referred to here as pets). Not only can ascarids and hookworms cause disease in their respective hosts, they are also well-known causes of larva migrans syndromes in humans, especially children. While ascarids and hookworms are most commonly diagnosed in puppies and kittens, infections can occur in dogs and cats of all ages. Dogs can also become infected with Baylisascaris procyonis, the common raccoon ascarid, which can cause serious disease in other animals and humans.
Ascarids — Because of the occurrence of both transplacental and transmammary transmission of T. canis, puppies are usually born with or acquire ascarid infections early in life. Kittens do not become infected in utero, but like puppies, can acquire ascarids (T. cati) through the queen's milk. The tissue-migrating and early intestinal stages of these worms may cause severe, sometimes life-threatening, disease in the first few weeks of life. Patent intestinal infections can develop within the first 2.5 - 3 weeks of life. Left untreated, this can lead to widespread contamination of the environment with infective eggs.
Hookworms — Both puppies and kittens acquire hookworm infections (A. caninum, A. braziliense, and A. tubaeforme) through ingestion of or skin penetration by infective larvae, or from infective larvae passed in their dam’s milk (A. caninum). Hookworms suck large amounts of blood from their hosts and while infected animals may look healthy in the first week of life, they can develop a rapidly severe, often fatal, anemia. Patent intestinal infections can occur as early as 2- (dogs) to 3- (cats) weeks of age, leading to environmental contamination with infective larvae.
The prevalence of these infections varies with climatic conditions; however, they are present in all parts of the United States and must be viewed as a potential public health hazard. Because puppies, kittens, and pregnant and nursing animals are at highest risk for these infections, and therefore responsible for most of the environmental contamination and human disease, anthelmintic treatments are most effective when they are initiated early and targeted at these populations.
Because puppies, kittens, and pregnant and nursing animals are at highest risk for these infections, and therefore responsible for most of the environmental contamination and human disease, anthelmintic treatments are most effective when they are initiated early and targeted at these populations.
While it has long been recognized that transplacental and transmammary infection of ascarids and hookworms could be prevented through prophylactic treatment of pregnant dogs, no drugs are currently approved for this use. However, the effectiveness of this approach with different drugs approved for parasite control in dogs has been well documented. Daily treatment of pregnant dogs with fenbendazole from the 40th day of gestation through the 14th day of lactation has been shown to inhibit T. canis larvae in tissues, thereby preventing or greatly reducing the incidence of infection in puppies.
Alternatively, studies have shown that treatment with ivermectin on day 0, 30, 60 of gestation and 10 days post whelping, reduced the adult T. canis worm burden in pups by 100% and prevented the shedding of eggs.20 In yet another study, treatment with selamectin at 10 and 40 days both before and after parturition was effective in reducing T. canis fecal egg counts in both pups and their dams, and adult worms in the pups. If the mother did not receive prophylactic treatment, puppies and kittens must be treated early and repeatedly in order to prevent patent infections.
Drugs for the treatment of ascarid and hookworm infections in
dogs and cats
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FDA Approved in: |
| Name |
Route of Administration / Frequency / Dose |
Range of Efficacy |
Species |
Minimum Age/Weight |
Diethyl-
carbamazine citrate1, 10 |
Oral
6.6 mg/kg daily |
DI |
Dog |
=8 weeks |
| 55-110
mg/kg once; repeat in 10-20 days |
A |
Diethyl-
carbamazine / oxibendazole1, 3, 4, 10 |
Oral/daily
6.6 mg/kg DEC
5.0 mg/kg OXI |
A, H,
W, DI |
Dog |
=8
weeks and =1 lb |
| Fenbendazole |
Oral/daily for 3 days
50 mg/kg |
A, H,
W, T |
Dog |
None |
| Ivermectin4, 10 |
Oral/monthly
24 µg/kg |
H,
DI |
Cat |
=6
weeks |
| Ivermectin / pyrantel pamoate1, 7, 10 |
Oral/monthly
6 µg/kg IVM
5 mg/kg PYR |
A, H,
DI |
Dog |
=6
weeks |
| Milbemycin oxime1, 4, 7, 10 |
Oral/monthly
Dog: 0.5 mg/kg |
A, H,
W, DI |
Dog |
=4
weeks and =2 lbs |
| Cat:
2.0 mg/kg |
A, H,
DI |
Cat |
=6
weeks and =1.5 lbs |
| Milbemycin oxime / lufenuron1, 4, 7, 10, 11 |
Oral/monthly
0.5 mg/kg MO
10 mg/kg LUF |
A, H,
W, DI |
Dog |
=4
weeks and =2 lbs |
| Moxidectin1, 4, 6, 10, 12 |
SC/twice yearly
0.17 mg/kg |
H,
DI |
Dog |
=6
months |
| Piperazine5 |
Oral/discretionary
See label for dose |
A |
Dog/cat |
=6
weeks |
| Pyrantel pamoate14 |
Oral/discretionary
5 mg/kg |
A,
H |
Dog |
=2
weeks |
| Pyrantel pamoate / praziquantel4, 13 |
Oral/discretionary
5 mg/kg PRA
20 mg/kg PYR |
A, H,
T, D |
Cat |
=1
month and =1.5 lbs |
| Pyrantel pamoate / praziquantel / febantel2, 9 |
Oral/discretionary
5 mg/kg PYR
5 mg/kg PRA
25 mg/kg
FEB |
A, H,
W, T, D, E |
Dog |
=3
weeks and =2 lbs |
| Selamectin4, 7, 8, 10 |
Topical/monthly
6mg/kg
S |
Dog:
DI |
Dog |
=6 weeks |
| Cat: A,
H, DI |
Cat |
- A = ascarids (Toxocara and Toxascaris spp.)
- H = hookworm Ancylostoma and Uncinaria spp.)
- W = whipworm (Trichuris vulpis)
- T = Taeniid tapeworms (Taenia pisiformis, Taenia
taeniaeformis, Taenia spp.)
- D = Flea tapeworm (Dipylidium caninum)
- E = Echinococcus granulosus, Echinococcus multilocularis
- DI = Dirofilaria immitis
Contraindications:
1Not for use in animals with established heartworm
infections. 2Do not use in pregnant animals. 3Do not
use in dogs with hepatic dysfunction. 4Not effective against
Uncinaria. 5Some salts not for use in unweaned
animals. 6See package insert for injection
technique. 7Safe in collies at label dose. 8Also
effective against fleas, flea eggs, ticks, and mites (including ear
mites). 9Repeat every 21 – 26 days for control of Echinococcus
multilocularis. 10Effective against tissue stage of heartworm
larvae. 11 Not a flea adulticide – contains an insect growth
regulator. 12Effective against hookworm larvae and adults at time
of injection only. 13Consult with veterinarian before using in
pregnant animals. 14Approved for use in lactating dogs (administer
2-3 weeks after parturition).
Adapted form:
1. Guidelines for Veterinarians: Prevention of Zoonotic Transmission of Ascarids and Hookworms of Dogs and Cats, Centers for Disease Control and Prevention, National Center for Infectious Diseases, Division of Parasitic Diseases
Go Pets America recommends seeking the advice of your local veterinarian for the most appropriate vaccination program and for the diagnosis and treatment of your pet's health problems. For vaccination requirements please contact your state and local licensing authorities.
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