Macracanthorhynchus spp

From Dog
The Giant Thorny-headed Worm (Macracanthorhynchus hirudinaceus)[1]

Macracanthorhynchus are an gigantorhynchiid acanthocephalan parasite.

This acanthocephalan is typically a parasite of the small intestine of pigs, raccoons, wolves, badgers, foxes, skunks, mink, and moles.

The anterior end of Macracanthorhynchus bears a spiny, retractable proboscis or rostellum used for firm attachment to the intestinal wall. Adult females shed embryonated eggs, laying ~260,000 eggs/day for several months[2]. The prepatent period is 2 - 3 months.

Transmission from wildlife to dogs may occur via ingestion of infected intermediate hosts (various beetles such as millipedes).

Species which have been reported in dogs include:

  • Macracanthorhynchus hirudinaceus[3]
  • Macracanthorhynchus ingens

This parasite has been routine found during coprological surveys of urban dogs[4].

Although commonly infect, few clinical signs associated with parasitism have been reported, primarily restricted to diarrhea.

Treatment is usually effective with epsiprantel (5.5 mg/kg) and ivermectin (250 - 500 μg/kg)[5].


  1. Redorbit
  2. Merck Vet Manual
  3. Dalimi A et al (2006) A study on intestinal helminthes of dogs, foxes and jackals in the western part of Iran. Vet Parasitol 142(1-2):129-33
  4. El-Shehabi FS et al (1999) Prevalence of intestinal helminths of dogs and foxes from Jordan. Parasitol Res 85(11):928-934
  5. Pearce JR et al (2001) Macracanthorhynchus ingens infection in a dog. J Am Vet Med Assoc 219(2):194-196