Acanthamoeba spp

From Dog
Acanthamoeba trophozoite under light microscopy[1]

Acanthamoeba spp are a zoonotic ameboid protozoan parasite of dogs, with prevalence rates of approximately 1% worldwide[2][3][4].

Species which are pathogenic to dogs include:

  • Acanthamoeba polyphaga
  • Acanthamoeba culbertsoni
  • Acanthamoeba castellani[5]

Acanthamoeba typically have a single host life cycle, and in dogs autochonous infections are common, particularly in densely housed kennels.

Infective sporozoites within oocysts are ingested by dogs and develop within the epithelium of the small intestine, undergoing schizogony to form schizonts. These schizonts can be found within enterocytes, biliary epithelium associated with hepatitis[6] and even the uterine epithelium[7].

Although normally nonpathogenic in dogs, Acanthamoeba should be considered in any dog which present with diarrhea, where this parasite appears more prevalent[8]. Mixed intestinal infections with Acanthamoeba and enteropathogenic bacteria (e.g. Salmonella spp) often exacerbated clinical diarrhea[9].

Infections appear to predominate in densely-housed kennels and pet shops, where infections with this parasite and Giardia spp can become endemic[10].

Systemic infections have been reported in immunosuppressed dogs, resulting in widespread organomegaly, discospondylitis, pneumonia[11] and encephalomyelitis[12][13].

Diagnosis is based on coprological identification of sporozoites. Isolation is maximized using 33% zinc sulfate[14].

A differential diagnosis would include other causes of coccidiosis such as Neospora spp, Balantidium coli, Giardia spp. Eimeria spp, Entamoeba histolytica and Isospora spp.

Treatment is usually effective with metronidazole or sulfaquinoxaline.

In dogs with systemic illness, prednisone (3.2 mg/kg orally once daily and azathioprine (2 mg/kg orally once daily) are recommended[15].


  1. CDC
  2. Beiromvand M et al (2012) Prevalence of zoonotic intestinal parasites in domestic and stray dogs in a rural area of Iran. Prev Vet Med Oct 5
  3. Tupler T et al (2012) Enteropathogens identified in dogs entering a Florida animal shelter with normal feces or diarrhea. J Am Vet Med Assoc 241(3):338-343
  4. Yamamoto N et al (2009) Prevalence of intestinal canine and feline parasites in Saitama Prefecture, Japan. Kansenshogaku Zasshi 83(3):223-228
  5. Pearce JR et al (1985) Amebic meningoencephalitis caused by Acanthamoeba castellani in a dog. J Am Vet Med Assoc 187(9):951-952
  6. Lipscomb TP et al (1989) Intrahepatic biliary coccidiosis in a dog. Vet Pathol 26(4):343-345
  7. Bowman, DD (2009) Georgis' parasitology for veterinarians. 9th edn. Elsevier Saunders, Missouri. pp:378-379
  8. Itoh N et al (2011) Giardia and other intestinal parasites in dogs from veterinary clinics in Japan. Parasitol Res 109(1):253-256
  9. Galván-Moroyoqui JM et al (2008) The interplay between Entamoeba and enteropathogenic bacteria modulates epithelial cell damage. PLoS Negl Trop Dis 2(7):e266
  10. Itoh N et al (2011) Prevalence of intestinal parasites and genotyping of Giardia intestinalis in pet shop puppies in east Japan. Vet Parasitol 176(1):74-78
  11. Bauer RW et al (1993) Isolation of Acanthamoeba sp. from a greyhound with pneumonia and granulomatous amebic encephalitis. J Vet Diagn Invest 5(3):386-391
  12. Brofman PJ et al (2003) Granulomatous amebic meningoencephalitis causing the syndrome of inappropriate secretion of antidiuretic hormone in a dog. J Vet Intern Med 17(2):230-234
  13. Dubey JP et al (2005) Disseminated Acanthamoeba sp. infection in a dog. Vet Parasitol 128(3-4):183-187
  14. Little SE et al (2009) Prevalence of intestinal parasites in pet dogs in the United States. Vet Parasitol 166:144–152
  15. Kent M et al (2011) Multisystemic infection with an Acanthamoeba sp in a dog. J Am Vet Med Assoc 238(11):1476-1481