New insight into factors associated with a common disease among dogs and humans

The pathogens Giardia duodenalis and Cryptosporidium are common causes of sometimes-fatal intestinal diseases in humans, other mammals and birds worldwide.

Now, findings from researchers at Texas A&M University provide new, evidence-based insight into minimizing the risk of these diseases at canine facilities.

“In adult, healthy humans and animals, these diseases usually cause diarrhea and occasionally other minor ailments, but for infants, puppies and the immunocompromised, infection could be deadly,” said Loni Taylor, PhD, DVM, an epidemiologist with the Texas A&M University School of Public Health, who led the study. “We wanted to identify the factors associated with kennel-housed dogs in Texas that test positive for both diseases.”

For their study, published in Comparative Medicine, Taylor and five colleagues with Texas A&M’s College of Veterinary Medicine & Biomedical Sciences sought to find out if a dog’s score on the Purina Fecal Scoring chart, breed, sex or age was associated with testing positive on a fecal screening test for either Giardia, Cryptosporidium or both organisms together.

To accomplish this, they tested fecal samples collected from a census sample of 153 clinically normal dogs housed at Texas kennels between March and October 2021. Breeds included golden retrievers, Labrador retrievers, beagles and a variety of large hounds and hound mixes.

The sex, age, breed and location were noted for the 153 dogs studied. In addition, fecal scores were determined by a single researcher using visual assessment of the samples, based on the Purina Institute metric (where 1 is hard and 7 is watery).

A secondary data analysis and statistical analysis found that dogs were significantly more likely to test positive for Giardia (45%) than Cryptosporidium (7%) (P < 0.01), although no clear link was found between sex or breed and these infections.

In addition, kennel-housed dogs 18 months of age or younger had 3.4 times the odds of Giardia infection compared with older dogs, and hard stool was associated with negative test status for Giardia in the stool.

No statistically significant relationship was found for age or fecal score and Cryptosporidium-positive test status, and Taylor noted that additional studies with larger sample sizes could help identify such a relationship.

“The primary takeaway is that age and fecal score are important factors for choosing which dogs to screen for subclinical Giardia,” Taylor said. “And given the increased odds of Giardia infection, screening should be as robust as the recommended combination of testing methods.”