Fecal score and age have an association with subclinical Giardia duodenalis infection in dogs, a recent study by Texas A&M University’s College of Veterinary Medicine & Biomedical Sciences (VMBS) and School of Public Health, found. The study, which was conducted on kennel dogs, offers insight into which dogs at kennel facilities should be screened for the parasite.
The research, led by Loni Taylor, PhD, DVM, MPH, an epidemiologist professor with the School of Public Health, and 5 colleagues with VMBS, looked at both Giardia and Cryptosporidium.1,2 More specifically, the study, published in Comparative Medicine, aimed to find demographic factors, including breed, sex, and age; and fecal scores from the Purina Fecal Scoring Chart, that were linked to positive screening test cases of Giardia and Cryptosporidium in kennel-housed laboratory dogs in Texas.1
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In the United States, Giardia, a zoonotic intestinal parasite affecting humans and animals, is transmitted via the fecal-oral route and is one of the most prevalent causes of waterborne diseases.1,3 According to the authors of the study, it was recently estimated that Giardia is present in 37% to 50% of kennel-housed dogs. Cryptosporidium, meanwhile, is reported to be found in 7% to 21% of these canines.1
“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 Taylor in a Texas A&M report.2 “We wanted to identify the factors associated with kennel-housed dogs in Texas that test positive for both diseases.”
The research team collected fecal samples from a census sample of 153 clinically normal dogs living in Texas kennels between March and October 2021, and noted participants’ sex, age, breed, and location. Samples were taken from golden retrievers, Labrador retrievers, beagles, and a variety of large hounds and hound mixes, according to Texas A&M.2
A single researcher identified the fecal score of the samples through a visual assessment using the Purina Institute metric. The Purina Fecal Scoring Chart that was used contains a visual guide and descriptions of 7 types of stools, varying from very hard and dry (score 1), to watery and flat (score 7).4 Three diagnostic tests, consisting of a human point-of-care coproantigen test, a direct immunofluorescent assay, and an in-house polymerase chain reaction, were used and evaluated simultaneously to determine positive results for Giardia and Cryptosporidium.1
Results
Sex and breed
Study results found no clear link between sex or breed and Giardia or Cryptosporidium infection. However, dogs were significantly more likely to test positive for Giardia than Cryptosporidium, with 45% of dogs testing positive for Giardia and 7% testing positive for Cryptosporidium.
Age
Additionally, kennel-housed dogs aged 18 months or younger had 3.4 times the odds (P = 0.009) of a subclinical Giardia infection compared to older dogs. No association was found between age and Cryptosporidium prevalence. According to Taylor, a larger sample size in future studies could help find a link between the two.2
Fecal score
Participants with hard stool were less likely to test positive for Giardia. However, there was no statistically significant relationship identified for fecal score and Cryptosporidium-positive test results.
“With these findings, we demonstrated the value of considering age and fecal score when choosing which dogs to screen for subclinical Giardia,” the study authors wrote.1
“Given the increased odds of Giardia infection, screening should be as robust as the recommended combination of testing methods,” Taylor said.2
References
- Taylor LA, Saleh MN, Kneese EC, Vemulapalli TH, Budke CM, Verocai GG. Investigation of factors associated with subclinical infections of Giardia duodenalis and cryptosporidium canis in kennel-housed dogs (canis lupus familiaris). Comparative Medicine. 2024;74(2):92-98. doi:10.30802/aalas-cm-24-000007
- Kellett A. New insight into factors associated with a common disease among dogs and humans. Vital Record. March 21, 2025. Accessed April 11, 2025. https://vitalrecord.tamu.edu/multidisciplinary-study-gives-new-insight-into-factors-associated-with-a-common-disease-among-dogs-and-humans/
- Giardia infection (giardiasis). Mayo Clinic. Accessed April 11, 2025. https://www.mayoclinic.org/diseases-conditions/giardia-infection/symptoms-causes/syc-20372786
- Purina Pro Plan Faecal Scoring Chart. Purina. Accessed April 11, 2025. https://vetcentre.purina.co.uk/sites/default/files/2021-11/Faecal%20scoring%20chart_general%20use.pdf
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