Risk factors for recurrence of Giardia duodenalis infection in dogs: a case-control study.

Objectives: To identify risk factors for recurrence of giardiasis in naturally infected symptomatic dogs after specific treatment.

Materials and methods: Medical records were retrospectively reviewed (2006 to 2016) for dogs diagnosed with symptomatic Giardia duodenalis infection. Signalment, housing conditions, clinical signs, concurrent diseases, treatments and outcome were recorded. Data were compared between dogs with and without symptomatic recurrence within 6 months of specific treatment using univariate analysis and multivariable logistic regression.

Results: Eighty-two dogs were included. Fifty-five were cured after treatment, and 27 had recurrent giardiasis. Factors significantly associated with recurrence on univariate analysis were age <6 months at first diagnosis, being a Retriever, living in a non-household environment or with other dogs, having concurrent chronic inflammatory enteropathy and having received a specific treatment other than fenbendazole or adjuvant probiotics. On multivariate analysis, retriever breed (odds ratio, 7.75; 95% confidence interval, 2.03 to 34.90), concurrent food-responsive enteropathy (odds ratio, 15.06; 95% confidence interval, 3.41 to 90.26) and adjuvant probiotics (odds ratio, 13.28; 95% confidence interval, 2.41 to 93.10) were independent risk factors for recurrence, while age >6 months at first diagnosis was a protective factor (odds ratio, 0.24; 95% confidence interval, 0.05 to 0.95).

Clinical significance: Not only are puppies and dogs living in communities at risk of G. duodenalis infection but they are also at higher risk of recurrence. Concurrent chronic inflammatory enteropathy should also be investigated in cases of symptomatic recurrence. These findings may provide indicators for the prevention and management of recurrent giardiasis in dogs.