Heartworm in Dogs in Canada in 1977 4.
J.O.D. SLOCOMBE*
In December 1977, 2804 questionnaires were sent to federal, provincial, industrial, institutional and large and small animal practitioners throughout Canada. The number returned was 746 (26% response). There were a few additional questionnaires which were not used because of lack of an address or indication of province. The findings are presented in two tables and two figures. A few brief comments should be made. 1. The percent response was not as high as for 1976, but it was most encouraging. There were slightly more responses from mixed and small animal practices than for 1976. A continuous surveillance with a similar questionnaire annually is proposed. 2. Heartworm was diagnosed in all provinces except Newfoundland and Prince Edward Island. The total number of cases in 197,7 (398) was slightly less than for 1976 (413), but a large number of respondents who diagnosed the condition in 1976 reported an increase in number of cases for 1977. 3. Respondents (80%) using blood tests routinely for diagnosis increased from 1976 but it should be higher. There was a significant increase in the use of concentration techniques in blood testing, but the use of the smear is still too high (29%) and due largely to some using it exclusively. There was a tendency for blood testing to be carried out principally in the spring which was recommended last year, but a large number of respondents provided no answer for question 7. Possibly wording of the question was
5.
6.
7.
confusing. Certainly question 10 was misinterpreted and the data should be treated cautiously. The most significant finding was that the majority of dogs with heartworm (58%) had never left Canada! For 1976 19% of the infected dogs were in this category and 67% were assumed to have contracted the infection outside of Canada. Undoubtedly, there appears to be at least two enzootic areas - one in Manitoba in the Winnipeg, Morden and Selkirk region and the other in Ontario in the Sarnia, Forest, Windsor, Essex, Wheatley region. In 1976 one additional focus was evident for the Brantford, Ontario area. This continues to be so and possibly enlarging to neighbouring Simcoe, Fisherville, Dunnville and Smithville. In Thorsby, Alberta there were two dogs with heartworm, but these dogs were originally in the Winnipeg area. Provincial veterinary associations should note that as was shown for 1976 a high proportion of the respondents welcomed information on heartworm and news releases to the public. All cases of heartworm in cats except one were diagnosed in Ontario and was one less than reported for 1976. Findings of heartworm in wildlife in Ontario for 1976 and 1977 suggests an accumulation of reservoir hosts. A brief mention on D. immitis in man. Overall the condition is rare and man is not a natural host. However, an increasing number of cases are being reported for the U.S.A. No cases have been reported for Canada. Many respondents provided candid comments which were quite useful and the enthusiastic response in both years is overwhelming. The data from this type of questionnaire obviously has inherent flaws, but it provides an "observer position" from which one can develop some hypotheses and I look forward to your continued support.
Acknowledgments This study was supported by grants from the Canadian Veterinary Research Trust Fund and from numerous Kennel Clubs across Canada. Special thanks are extended to Dr. Ian McMillan and Mrs. Margaret Quinton for preparing the computer program for analysis of the data.
*Department of Pathology, Ontario Veterinary College, University of Guelph, Guelph, Ontario NIG 2WI.
244
Can. vet. J. 19: 244-247 (September 1978)
TABLE I THE RESULTS OF A QUESTIONNAIRE WHICH WAS SENT TO 2804 VETERINARIANS IN CANADA IN DECEMBER 1977 AND COMPILED FROM 746 REPLIES
HEARTWORM IN CANADA - 1977 NAME:
ADDRESS:
1. Do you examine dogs, cats or any animal which could be infected with Dirofilaria immitis. YES 443 NO 303 If YES go to question 2. If NO go to question 20. 2. Which category would best fit your activity. Mixed practice 148 Small animal practice 246 Research Laboratory 9 Diagnostic Laboratory 26 Other (specify) 12 3. Did you diagnose heartworm in dogs in your area in 1976? YES 23% NO 4. If you did has there been an increase in incidence in 1977? YES 36% NO 5. Which technique(s) do you use routinely for diagnosis of heartworm? % Clinical signs 39 Blood tests 80 Radiography 12 Necropsy 19 6. Which blood tests do you use routinely? % Knott's 36 Filter 54 Smear 29 Other (specify) 9 Microcapillary tube 14 7. Do you confine your blood tests to set times during the year? % If YES when All Year I Winter I Spring 8 Summer 4 Fall 1 8. Approximately how many dogs did you blood test in 1977? 16563 9. Approximately how many dogs did you diagnose with heartworm in 1977? 398 10. Approximately how many of these dogs showed clinical signs? 123 11. Circle the month(s) you diagnose most heartworm cases in dogs: % Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. 13 19 4 10 10 14 12 7 4 3 4 0 12. In 1977 how many positive dogs had the following histories? Six months or more prior to diagnosis was outside of Canada 78 (20%) Never left Canada 232 (58%) Movement unknown 88 (22%) 13. Use numbers 1, 2, 3 and give frequency (most frequent = 1) for the domicile of dogs positive for heartworm in 1977. City 3 Suburban 2 Rural I 14. Use numbers 1, 2, 3, 4, 5 and give frequency (most frequent = 1) for the ages of dogs positive for heartworm in 1977. Less than I year 5 1-3 years 1 4-7 years 2 Greater than 7 years 3 Age unknown 4 15. Use numbers 1, 2, 3, 4, 5 and give frequency (most frequent = 1) for the following classification of dogs positive for heartworm in 1977. House dog only I Show dog 5 Farm dog 4 Hunting dog 2 Other (specify) 3 16. Do you recommend to your clients a preventive program for your area? YES 16% NO 17. Approximately how many cases of Dipetalonema reconditum in dogs did you diagnose in 1977. 65 18. Approximately how many cases of D. immitis in cats did you diagnose in 1977. 16 19. Approximately how many cases of D. immitis in other animals. If so specify type and number: 2 - one racoon and one fox, Brantford, Ontario 20. Would you be interested in the results of this questionnaire? YES 90% NO 21. Would you be interested in information on heartworm? NO YES 82% 22. Would news releases on heartworm be helpful to the public? YES 70% NO 23. Did you respond to the 1976 heartworm questionnaire? YES 65% NO 24. Was the report on the results of the 1976 questionnaire useful? YES 62% NO 25. Any other comments:
245
TABLE II AREAS WITH THREE OR MORE CASES OF HEARTWORM IN DOGS IN 1977 Area
Number of Cases Had been outside of Canada or Never left Canada Movement Unknown
Calgary, Alberta Saskatoon, Saskatchewan Selkirk, Manitoba Winnipeg, Manitoba Amherstburg, Ontario Brantford, Ontario Essex, Ontario Forest, Ontario Hamilton, Ontario Norwich, Ontario Samia, Ontario Stratford, Ontario Toronto, Ontario Thunder Bay, Ontario Wheatley, Ontario Windsor, Ontario Montreal, Quebec St. Stephen, New Brunswick Amherst, Nova Scotia
6 3 0 7 21 6 2 3 7 17 8 3 3 3 1 27 6 3 5
0 0 18 32 0 3 38 6 0 0 9 0 1 0 7 106 0 0 0
1117,
,BADDECK
--AMHERST -SACKVILLE
FIGURE 1. Areas with diagnoses of heartworm in dogs in Canada in 1977. * Areas with dogs which had been outside of Canada previously and presumed infected before returning or with dogs whose moments were unknown. A Areas with dogs some of which had never left Canada and were infected in Canada.
246
KENORA i
_
*DRYDEN R~~~DE BAY
_
KINGSTON
*- BRIGHTON
SCARBOROUGH
AYLMER WHEATLEY ESSEX
"
'BRANTFORD
SIMCOE NORWICH
1HERSTBURG FIGURE 2. Areas with diagnoses of heartworm in dogs in Ontario in 1977. * Areas with dogs which had been outside of Canada previously and presumed infected before returning or with dogs whose movements were unknown. A Areas with dogs some of which had never left Canada and were infected in Canada.
APPLICATIONS INVITED Applications are invited for grants in aid of research on animal disease in Canada. Preferred application date is by January 31 for consideration in April each year. For further information contact: J.R. Kinney, Secretary Canadian Veterinary Research Trust Fund 360 Bronson Avenue Ottawa, Ontario K 1 R 6J3
DEMANDE POUR FONDS DE RECHERCHE Nous invitons les demandes de fonds de recherche sur les maladies animales au Canada. La date de fermeture pour les applications est le 31 janvier et elles seront considerees en avril de chaque annee. Pour plus d'informations, veuillez vous adresser a: J.R. Kinney, secretaire La fondation canadienne pour la recherche veterinaire 360 avenue Bronson Ottawa, Ontario KI R 6J3
247
J.O.D. SLOCOMBE*
In December 1977, 2804 questionnaires were sent to federal, provincial, industrial, institutional and large and small animal practitioners throughout Canada. The number returned was 746 (26% response). There were a few additional questionnaires which were not used because of lack of an address or indication of province. The findings are presented in two tables and two figures. A few brief comments should be made. 1. The percent response was not as high as for 1976, but it was most encouraging. There were slightly more responses from mixed and small animal practices than for 1976. A continuous surveillance with a similar questionnaire annually is proposed. 2. Heartworm was diagnosed in all provinces except Newfoundland and Prince Edward Island. The total number of cases in 197,7 (398) was slightly less than for 1976 (413), but a large number of respondents who diagnosed the condition in 1976 reported an increase in number of cases for 1977. 3. Respondents (80%) using blood tests routinely for diagnosis increased from 1976 but it should be higher. There was a significant increase in the use of concentration techniques in blood testing, but the use of the smear is still too high (29%) and due largely to some using it exclusively. There was a tendency for blood testing to be carried out principally in the spring which was recommended last year, but a large number of respondents provided no answer for question 7. Possibly wording of the question was
5.
6.
7.
confusing. Certainly question 10 was misinterpreted and the data should be treated cautiously. The most significant finding was that the majority of dogs with heartworm (58%) had never left Canada! For 1976 19% of the infected dogs were in this category and 67% were assumed to have contracted the infection outside of Canada. Undoubtedly, there appears to be at least two enzootic areas - one in Manitoba in the Winnipeg, Morden and Selkirk region and the other in Ontario in the Sarnia, Forest, Windsor, Essex, Wheatley region. In 1976 one additional focus was evident for the Brantford, Ontario area. This continues to be so and possibly enlarging to neighbouring Simcoe, Fisherville, Dunnville and Smithville. In Thorsby, Alberta there were two dogs with heartworm, but these dogs were originally in the Winnipeg area. Provincial veterinary associations should note that as was shown for 1976 a high proportion of the respondents welcomed information on heartworm and news releases to the public. All cases of heartworm in cats except one were diagnosed in Ontario and was one less than reported for 1976. Findings of heartworm in wildlife in Ontario for 1976 and 1977 suggests an accumulation of reservoir hosts. A brief mention on D. immitis in man. Overall the condition is rare and man is not a natural host. However, an increasing number of cases are being reported for the U.S.A. No cases have been reported for Canada. Many respondents provided candid comments which were quite useful and the enthusiastic response in both years is overwhelming. The data from this type of questionnaire obviously has inherent flaws, but it provides an "observer position" from which one can develop some hypotheses and I look forward to your continued support.
Acknowledgments This study was supported by grants from the Canadian Veterinary Research Trust Fund and from numerous Kennel Clubs across Canada. Special thanks are extended to Dr. Ian McMillan and Mrs. Margaret Quinton for preparing the computer program for analysis of the data.
*Department of Pathology, Ontario Veterinary College, University of Guelph, Guelph, Ontario NIG 2WI.
244
Can. vet. J. 19: 244-247 (September 1978)
TABLE I THE RESULTS OF A QUESTIONNAIRE WHICH WAS SENT TO 2804 VETERINARIANS IN CANADA IN DECEMBER 1977 AND COMPILED FROM 746 REPLIES
HEARTWORM IN CANADA - 1977 NAME:
ADDRESS:
1. Do you examine dogs, cats or any animal which could be infected with Dirofilaria immitis. YES 443 NO 303 If YES go to question 2. If NO go to question 20. 2. Which category would best fit your activity. Mixed practice 148 Small animal practice 246 Research Laboratory 9 Diagnostic Laboratory 26 Other (specify) 12 3. Did you diagnose heartworm in dogs in your area in 1976? YES 23% NO 4. If you did has there been an increase in incidence in 1977? YES 36% NO 5. Which technique(s) do you use routinely for diagnosis of heartworm? % Clinical signs 39 Blood tests 80 Radiography 12 Necropsy 19 6. Which blood tests do you use routinely? % Knott's 36 Filter 54 Smear 29 Other (specify) 9 Microcapillary tube 14 7. Do you confine your blood tests to set times during the year? % If YES when All Year I Winter I Spring 8 Summer 4 Fall 1 8. Approximately how many dogs did you blood test in 1977? 16563 9. Approximately how many dogs did you diagnose with heartworm in 1977? 398 10. Approximately how many of these dogs showed clinical signs? 123 11. Circle the month(s) you diagnose most heartworm cases in dogs: % Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. 13 19 4 10 10 14 12 7 4 3 4 0 12. In 1977 how many positive dogs had the following histories? Six months or more prior to diagnosis was outside of Canada 78 (20%) Never left Canada 232 (58%) Movement unknown 88 (22%) 13. Use numbers 1, 2, 3 and give frequency (most frequent = 1) for the domicile of dogs positive for heartworm in 1977. City 3 Suburban 2 Rural I 14. Use numbers 1, 2, 3, 4, 5 and give frequency (most frequent = 1) for the ages of dogs positive for heartworm in 1977. Less than I year 5 1-3 years 1 4-7 years 2 Greater than 7 years 3 Age unknown 4 15. Use numbers 1, 2, 3, 4, 5 and give frequency (most frequent = 1) for the following classification of dogs positive for heartworm in 1977. House dog only I Show dog 5 Farm dog 4 Hunting dog 2 Other (specify) 3 16. Do you recommend to your clients a preventive program for your area? YES 16% NO 17. Approximately how many cases of Dipetalonema reconditum in dogs did you diagnose in 1977. 65 18. Approximately how many cases of D. immitis in cats did you diagnose in 1977. 16 19. Approximately how many cases of D. immitis in other animals. If so specify type and number: 2 - one racoon and one fox, Brantford, Ontario 20. Would you be interested in the results of this questionnaire? YES 90% NO 21. Would you be interested in information on heartworm? NO YES 82% 22. Would news releases on heartworm be helpful to the public? YES 70% NO 23. Did you respond to the 1976 heartworm questionnaire? YES 65% NO 24. Was the report on the results of the 1976 questionnaire useful? YES 62% NO 25. Any other comments:
245
TABLE II AREAS WITH THREE OR MORE CASES OF HEARTWORM IN DOGS IN 1977 Area
Number of Cases Had been outside of Canada or Never left Canada Movement Unknown
Calgary, Alberta Saskatoon, Saskatchewan Selkirk, Manitoba Winnipeg, Manitoba Amherstburg, Ontario Brantford, Ontario Essex, Ontario Forest, Ontario Hamilton, Ontario Norwich, Ontario Samia, Ontario Stratford, Ontario Toronto, Ontario Thunder Bay, Ontario Wheatley, Ontario Windsor, Ontario Montreal, Quebec St. Stephen, New Brunswick Amherst, Nova Scotia
6 3 0 7 21 6 2 3 7 17 8 3 3 3 1 27 6 3 5
0 0 18 32 0 3 38 6 0 0 9 0 1 0 7 106 0 0 0
1117,
,BADDECK
--AMHERST -SACKVILLE
FIGURE 1. Areas with diagnoses of heartworm in dogs in Canada in 1977. * Areas with dogs which had been outside of Canada previously and presumed infected before returning or with dogs whose moments were unknown. A Areas with dogs some of which had never left Canada and were infected in Canada.
246
KENORA i
_
*DRYDEN R~~~DE BAY
_
KINGSTON
*- BRIGHTON
SCARBOROUGH
AYLMER WHEATLEY ESSEX
"
'BRANTFORD
SIMCOE NORWICH
1HERSTBURG FIGURE 2. Areas with diagnoses of heartworm in dogs in Ontario in 1977. * Areas with dogs which had been outside of Canada previously and presumed infected before returning or with dogs whose movements were unknown. A Areas with dogs some of which had never left Canada and were infected in Canada.
APPLICATIONS INVITED Applications are invited for grants in aid of research on animal disease in Canada. Preferred application date is by January 31 for consideration in April each year. For further information contact: J.R. Kinney, Secretary Canadian Veterinary Research Trust Fund 360 Bronson Avenue Ottawa, Ontario K 1 R 6J3
DEMANDE POUR FONDS DE RECHERCHE Nous invitons les demandes de fonds de recherche sur les maladies animales au Canada. La date de fermeture pour les applications est le 31 janvier et elles seront considerees en avril de chaque annee. Pour plus d'informations, veuillez vous adresser a: J.R. Kinney, secretaire La fondation canadienne pour la recherche veterinaire 360 avenue Bronson Ottawa, Ontario KI R 6J3
247
