Isospora spp

From Dog
Isospora felis under light microscopy[1]

Isospora spp are an ampicomplexan protozoan parasite of dogs, with prevalence rates of approximately 1 - 10% worldwide[2][3][4][5].

Species which are pathogenic to dogs include:

Although normally nonpathogenic in dogs, Isospora should be considered in any dog which present with diarrhea, where this parasite appears more prevalent[6].

Infections appear to predominate in densely-housed kennels and pet shops, where infections with this parasite and Giardia spp can become endemic[7].

Diagnosis is based on coprological identification of crescent-shaped sporozoites surrounded by a thick cyst wall within a parasitophorous vacuole[8][9]. Isolation is maximized using 33% zinc sulfate[10].

Treatment is usually effective with metronidazole or emodepside[11][12].


  1. University of California, Davis
  2. Becker AC et al (2012) Prevalence of endoparasites in stray and fostered dogs and cats in Northern Germany. Parasitol Res 111(2):849-857
  3. 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
  4. 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
  5. Gingrich EN et al (2010) Intestinal parasites of dogs on the Galapagos Islands. Vet Parasitol 169(3-4):404-407
  6. Itoh N et al (2011) Giardia and other intestinal parasites in dogs from veterinary clinics in Japan. Parasitol Res 109(1):253-256
  7. 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
  8. Lappin MR (2011) Update on the diagnosis and management of Isospora spp infections in dogs and cats. Top Companion Anim Med 25(3):133-135
  9. Mitchell SM et al (2009) Development and ultrastructure of Cystoisospora canis Nemeséri, 1959 (syn, Isospora canis) monozoic cysts in two noncanine cell lines. J Parasitol 95(4):793-798
  10. Little SE et al (2009) Prevalence of intestinal parasites in pet dogs in the United States. Vet Parasitol 166:144–152
  11. Altreuther G et al (2011) Field evaluations of the efficacy and safety of Emodepside plus toltrazuril (Procox® oral suspension for dogs) against naturally acquired nematode and Isospora spp. infections in dogs. Parasitol Res 109(1):S21-S28
  12. Altreuther G et al (2011) Efficacy of emodepside plus toltrazuril suspension (Procox(®) oral suspension for dogs) against prepatent and patent infection with Isospora canis and Isospora ohioensis-complex in dogs. Parasitol Res 109(1):S9-S20