The canine nematode and Giardia spp. infections in dogs in Edmonton, Alberta, the “CANIDA” study | Parasites and vectors

Study zone

Participants were recruited in Edmonton, Alberta, Canada. The Edmonton metro area has a population of approximately 1.4 million and just over 56,000 registered dogs [18, 19]. It has one of the largest urban recreational park systems in North America, centered around the North Saskatchewan River which runs through the city (City of Edmonton website). These natural areas are frequently used for recreation, including dog walking, and support a resident population of coyotes. Seven urban parks dedicated to off-leash dogs (hereafter “dog parks”) were chosen for sampling. Surveys from these parks were collected on at least 3 consecutive days in early summer (May or June) and then again in late summer (July and August) of 2020, with the exception of one park that was not revisited at the end of the summer. Ten percent of participants were recruited through an online survey or approached at smaller residential parks that were only visited once. Participants recruited online completed the questionnaire before being met individually for sample collection.

Questionnaire design

A modified form of the survey tool used by Smith et al. was used and divided into different sections [4, 5]. The first section included questions for selecting participants to be included in the survey. The second section focused on dog demographic details such as sex, breed, age class, neutering status, veterinary care, and deworming practices. The following sections were specific to dog owner behavior, including dog walking routines and off-leash activity levels. Questions regarding dog behavior during walks, including topics such as prey hunting and fetching activity, were also included. A 6-point Likert-type scale (ranging from never to always/daily) was used to record the frequency of walking behavior at different types of locations as well as the frequency of off-leash activity at these locations. To be included in the study, participants had to agree to answer screening questions, complete the entire survey, and provide a fecal sample. The project received ethical approval from the King’s University Ethics Committee (2017-08-DRV).

Fecal analysis

Participants were asked to collect a fresh fecal sample from their dog and give it to the researcher before leaving the park. Fecal samples were stored in coolers until the end of the day before being processed in 1.5 ml centrifuge tubes and frozen at -18°C on the same day as collected until collected. they are sent for analysis. While awaiting transfer, samples were held at −80°C for at least 72 h to inactivate any virulent virus. Echinococcus eggs that may be present in the samples [6]. The samples were transferred to the IDEXX Reference Laboratory in Sacramento, California, USA. Samples were tested by fecal flotation with centrifugation with zinc sulphate (density 1.24-1.27) as well as hookworms, roundworms, whipworms and Giardia spp. Coproantigen immunoassays. The coproantigen immunoassays in this study used polyclonal and monoclonal antibodies developed by IDEXX Laboratories against recombinantly expressed proteins to T.canis, A.caninum, T.vulpisand Giardia spp. Sensitivity, specificity and detection limits have been described previously [7, 15, 16]. Samples were also tested using a real-time polymerase chain reaction targeting both Echinococcus spp. and E.multilocularis (IDEXX Laboratories Echinococcus RealPCR™ Panel) using proprietary forward and reverse primers and hydrolysis probes.17

Statistical analyzes

Faecal samples were tabulated by number and proportion positive for flotation, coproantigen or both methods combined (either/or could be positive). Data from the questionnaire was compiled as frequency and proportion of responses. Tests for paired proportions were performed using McNemar’s exact test at mid-p. Due to the low percentage of positive parasites, a logistic regression penalized by Firth was used to estimate the odds of having (any) positive parasite found with the following questionnaire covariates: Does your dog hunt wildlife on walks or at home? (Yes, reference: No). Has your dog ever been fed entrails and internal organs (Yes, reference: No). How often, if at all, is your dog off leash? (Often/Often/Always, reference: Never/Rarely/Sometimes). Does your dog eat things he finds on the floor on his walks? (Yes, reference: No). How many times, if any, have you walked your dog (on or off leash) in the following areas in the past 6 months? (reference: minimal (


A total of 775 surveys were conducted at Canadian dog parks in and around Edmonton, Alberta, Canada. Data consisted of 774 unique fecal specimens tested by coproantigen with flotation by zinc sulfate centrifugation. Dogs were evenly split by sex, with females accounting for 48.1% (not = 373) of the samples collected. Neutered or neutered dogs accounted for 89.9% (not = 697) of the dogs that participated in the study.

The median age was 4 years and most dogs (58.6%) were of mixed breed. Based on owner responses, 93.4% of dogs have been seen by a veterinarian in the past year; 63.6% of owners indicated that their dog had been wormed in the past year. Most (60.3%) of owners also indicated that given the opportunity their dogs would pursue small prey such as rodents, although most rated their dogs as “unlikely” to successfully capture or eat their prey. Most owners said their dogs scavenge from the ground, with grass and feces being the two most common targets at dog parks and on walks (85.2%).

Coproantigen tests detected more roundworms (roundworms, hookworms and whipworms) and Giardiaspp.-positive, as well as detection of all positive results found by flotation alone (Table 1, Fig. 1). Giardiaspp. was the most commonly identified intestinal parasite, with coproantigen detecting 5.8% (45/774) of positive samples compared to flotation, which identified 3.2% (25/774) of positive samples (McNemar mi –P-value P-value = 0.063) and hookworms (coproantigen: 1.2%, 9/74 flotation: 0.3% 2/774, McNemar mid-P -value P -value = 0.500). Tapeworm and Cystoisospora had the lowest percentage of positive samples, each with 0.1% detected by flotation (1/774). Eimeria spp., a common pseudoparasite that can be confused with Cystoisospora spp., was observed in 2.1% (flotation: 2.1%, 16/774) of the samples collected (Table 1). Fecal results showed that 8.0% (not = 62) of dogs that tested positive for hookworm, roundworm, whipworm or Giardiaspp. using any method (Table 1, Fig. 2).

Table 1 Percentage of positives by method and by parasite
Fig. 1

Percent positive for each of the intestinal parasites by method and combined (O&P or antigen)

Figure 2
Figure 2

Percent positive for roundworms (hookworms, roundworms and whipworms) and roundworms plus Giardiaspp. by method and combined (O&P or antigen)

Combined flotation and coproantigen positivity from the Alberta region was compared to parasite positivity previously reported for three northwestern US cities in the DOGPARCS study (Fig. 3). The combined percentage of buoyancy and positive coproantigen was higher in the Northwestern United States for Giardiaspp. while the percentage of roundworms found in dog parks was higher in Alberta. Similar positive percentages in the Northwestern United States and Alberta were found for hookworms and whipworms (Fig. 3).

Figure 3
picture 3

Percentage of positives for each of the intestinal parasites for the combined method (O&P or antigen) between the northwestern United States (Portland, Boise and Seattle according to the DOGPARC study) compared to samples collected around Alberta , in Canada

Dog owners were asked about the frequency of administration of intestinal parasites/heartworm prevention. When asked about the use of parasite/heartworm prevention throughout the year, 63.6% answered “yes”, 26.9% answered “no” and 9.5% answered “unknown” “. Owners who reported that their dog received annual parasite/heartworm preventative treatment had a combined positivity of 12.4% for both methods and all parasites. Owners who said their dog did not receive annual preventative treatment or did not know had a combined positivity of 6.3% and 12.3% for all parasites, respectively.

A regression model was developed to better understand the factors increasing the likelihood of having a parasitic infection. Age was observed to have a nonlinear association with parasite infection. Young dogs had an increased risk of getting a parasitic infection, which steadily decreased until they were 6 years old (P

Figure 4
number 4

Firth-Penalized regression model showing a nonlinear association between any parasitic infection and age

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