General Information for Western Canada

The findings in 1998 for Western Canada are presented in one figure and five tables and a few comments about these should be made.

1. In 1998, 758 questionnaires were sent out and at present 290 have been returned, but 14 were rejected for reasons indicated above (38.9% response). For those responding, 96% indicated a willingness to complete a questionnaire if it was offered again. There were 132 completed questionnaires from British Columbia (35.7% response), 88 from Alberta (39.6% response), 24 from Saskatchewan (27.0% response) and 40 from Manitoba (73.0% response).

2. There were 30 dogs with HW in Western Canada (41 in 1997); 2 in BC, 3 in Alberta and 25 in Manitoba. One of these dogs had been diagnosed with HW and reported on previously and since then was untreated.

3. Similar numbers of dogs were blood tested in 1998 (31,014) and in 1997 (31,247). About 86% of the respondents used antigen techniques and less than 11% used microfilariae procedures. About 19% of the respondents had samples processed at a central lab.

4. HW was most frequent in companion dogs over three years of age and primarily from rural areas.

5. Sixteen of the infected dogs had never left their provinces, 3 had been away from Canada, 2 had visited other provinces and for 9 the movement was unknown.

6. There were 14 dogs with HW which were not treated and 4 were euthanized.

7. I sought from practitioners information on whether dogs tested for HW in 1998 had been on preventive medication in 1997. That data is useful to provide an estimate of the prevalence of HW in dogs that are unprotected and the level of risk of infection to dogs in the area. But many practitioners did not have that detailed information and the results reported in Tables 1-3 should be considered with caution. The prevalence of HW in unprotected dogs for any town can be determined using the data in both Tables 4 and 5. The sample size for a town or city is usually small and again caution should be used in interpreting the results.

8. In 1998, 10 dogs diagnosed with HW were given preventive medication in 1997; 2 ivermectin and 8 milbemycin. Four of these dogs were labelled as "Missed treatment" and 6 were placed in the category "Other".

9. In these surveys, I had requested respondents to indicate whether the data provided for the several questions in the questionnaire were taken from medical records (Question 25, Tables 1-3). There are several parts to that question and for Western Canada, the responses ranged from 19-53%. You should note that answers reported especially for Questions 19, 20 and 21 are approximations since only a small percentage of the respondents provided data from medical records.

10. There were 19 clinics in 10 towns reporting a diagnosis of HW in Western Canada in 1998 (19 clinics and 12 towns in 1997).