Coccidiosis: Diagnosis and Precautions

Coccidiosis causes diarrhea in young or immune-compromised dogs.  In a study by Mitchell et. al (2007), 8 six to eight-week-old beagles were used to determine the role of I. canis in pathogenicity of diarrhea observed in infected dogs to rule out other causes, such as bacteria or viruses.  The puppies were infected orally with sporulated Isospora canis oocysts that had been extracted from the feces of two pitbull puppies.  The inoculum given was first treated with a bleach mixture to kill any bacteria before being exposed to the dogs.  Oocysts were mixed with Hill’s Science Diet dog food and fed to the experimental beagles. 
Fecal samples were examined by centrifugal flotation in Sheathers’ sugar solution the day before infection, day of infection, and days 1-29 post-infection.  When a dog first became positive in the study, quantitative oocyst counts were taken from the feces.  Upon becoming apparent, clinical signs of infected dogs were recorded daily and fecal samples were given a score of 1 to 4; 1 being normal and 4 being completely liquid.  It was also noted if blood or mucous was seen.  During the course of the study, five dogs were treated with 25mg/kg sulfadimethoxine, an anticoccidial drug, for two to three days due to severe diarrhea.

            Two dogs showing clinical signs of coccidiosis were necropsied ten days after the onset of infection.  Developmental stages of I. canis were detected in cells of the mucous membranes lining the small intestine in both dogs.  Microscopic lesions were observed due to swelling of the villi that line the small intestine (villous atrophy), expansion of lacteals (lymphatic capillary that absorbs dietary fats in the villi of the small intestine), and hyperplasia (enlargement) of lymph nodes (Montague, Watson & Herbert, 2005).  Bacterial and viral examinations were negative, proving that intestinal coccidiosis was the cause diarrhea.  All stages of the lifecycle of I. canis were present in the small intestine of these dogs.  Immunohistochemistry was done to determine whether developmental stages of I. canis contained cross-reactive antigens to similar parasites.  Developmental stages of I. canis did not react with antibodies of other parasites. 

            Results of the overall experiment demonstrated that clinical coccidiosis was induced in all dogs that had been infected.  Fecal scores of 3 or 4 were usually recorded, indicating severe diarrhea, and were usually seen two to three days before oocysts were passed with stool.  Clinical signs were consistent and included watery or bloody diarrhea, anorexia, weight loss, vomiting, and lethargy.  Increased rectal temperatures were also noted in most dogs.  All dogs excreted I. canis oocysts.  On average, infected dogs began releasing oocysts in their stool 9.8 days after infection by I. canis.  The time period in which the dogs released oocysts lasted on average 8.9 days.

To help prevent the spread of coccidiosis in kennels and catteries, it is important to use appropriate sanitation practices.  Because oocysts sporulate (asexually reproduce and release spores) immediately once in the environment and can survive for months, daily removal of feces can aid in preventing transmission of coccidiosis (Princeton University, n.d.).  After oocysts become infective, they are resistant to most commonly used disinfectants (CAPC, n.d.).  You should also regularly remove your dog’s and cat’s feces from your own yard to keep the yard free of potentially infectious feces or reinfection by ingestion of coccidia.  Predation should be discouraged to prevent infection caused by paratenic hosts (those that are not needed for the development of the parasite but aid in maintaining the lifecycle of the parasite (Roberts & Janovy Jr., 2005)).

Now that you know all about coccidiosis, especially isosporiasis, you can keep a closer watch on your pets, Kit Kat and Beau, for signs of infection.  As a precaution, you should bring a stool sample from your pet with you to his/her yearly appointment to have it checked for coccidia and other intestinal parasites.  As long as you are aware, you cannot stop your pets from becoming infected but you can try to avoid it, as well as get them treatment if needed to combat the infection early on before isosporiasis has a chance to cause major problems.

References

Companion Animal Parasite Council (CAPC). (n.d.). Current advice on parasite control: Intestinal parasites - coccidia. Retrieved from http://www.capcvet.org/capc-recommendations/coccidia/

Mitchell, S. M. et. al. (2007). Cystoisospora canis nemeseri, 1959 (syn. isospora canis), infections in dogs: Clinical signs, pathogenesis, and reproducible clinical disease in beagle dogs fed oocysts. Journal of Parasitology, 93(2), 345-352. Retrieved from http://0-ehis.ebscohost.com.www.consuls.org/ehost/pdfviewer/pdfviewer?vid=14&hid=2 3&sid=c1bb8c4a-33f9-401f-a4f3-67f863bef1c3@sessionmgr13

Montague, S. E., Watson, R., & Herbert, R. (2005). Physiology for nursing practice. (3 ed., p. 494). Elsevier. Retrieved from http://books.google.com/books?id=nddqAAAAMAAJ&dq=lacteal+chyle&q=lacteal+

Princeton University. (n.d.). Wordnet search - 3.1. Retrieved from http://wordnetweb.princeton.edu/perl/webwn?s=sporulation

Roberts, L. S., & Janovy Jr., J. (2005). Foundations of parasitology. (7th ed., p. 4). New York, NY: The McGraw-Hill Companies, Inc.