Abstract
The distribution of diagnoses of mortality in mink submitted to the Danish Veterinary Laboratory (DVL) for diagnostic investigation in the calendar year 1997 was compared with the diagnoses of mortality in all dead mink collected at 4 selected farms (project farms) during the same period. A total of 1,015 submitted mink and 1,149 mink from the 4 project farms were subjected to post mortem investigation. The average size (breeding stock) of the project farms was larger than Danish farms on average. However, the distribution of colour types of the mink was comparable. The seasonal distribution of the material from project farms and that of the submissions were approximately the same. Differences in the distribution of diagnoses as well as recovered microorganisms were found, however, mainly related to the proportion of gastro-intestinal disorders and E. coli respectively. These proportions were negatively correlated. Overall the results showed that extrapolating diagnostic results of laboratory submissions to the population of farmed mink may be problematic, and more reliable methods for disease surveillance must be considered.
Keywords: fur animals, epidemiology, mortality rate, proportional mortality, bias, pathology, microbiology
Sammendrag
Kan materiale (kadavere af mink) indsendt til diagnostisk undersøgelse ved Statens Veterinære Serumlaboratorium anses for repræsentativt for dødeligheden i minkbesætninger generelt, hvad angår årstidsvariation, diagnosefordeling og fund af isolerede mikroorganismer? Dette blev undersøgt for kalenderåret 1997 ved sammenlignelig undersøgelse af alle døde mink fra 4 udvalgte farme (projektfarme) med materialet indsendt til diagnostisk undersøgelse (indsendelser). I alt 1237 døde indsendte mink og 1149 mink fra projektfarme blev obduceret. Størrelsen af projektfarmene var i gennemsnit større end gennemsnittet af danske minkfarme, men farvetypesammensætningen var nogenlunde ens. Der fandtes kun mindre forskel på fordelingen af den månedlige mortalitetsrate på projektfarmene og antallet af indsendelser til diagnostisk undersøgelse. Der fandtes derimod signifikant forskel på diagnosefordelingen samt fordelingen af isolerede mikroorganismer. Disse forskelle, der hovedsageligt var relateret til gastrointestinale lidelser og forekomsten af E. coli, var modsat rettede, idet der fandtes hyppigere forekomst af gastrointestinale lidelser blandt projektminkene, mens andelen af E. coli var højere blandt de indsendte mink. Resultaterne viser, at materiale indsendt til diagnostisk undersøgelse fra farmmink er mindre anvendeligt til sygdomsovervågning, hvor diagnosefordeling er formålet. Andre metoder til indsamling af data er nødvendige.
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References
- Christensen J, Svensmark B. Evaluation of producer-recorded causes of preweaning mortality in Danish sow herds. Prev.Vet.Med. 1997;32:155–164. doi: 10.1016/S0167-5877(96)01147-6. [DOI] [PubMed] [Google Scholar]
- Clausen P: De yngre pelsdyravlere har mod på fremtiden (“Young fur animal breeders are confident as to the future”) Dansk Pelsdyravl 1997a, 60, 239–240.
- Clausen P: Avlsresultater 1997 (“Breeding results 1997”). Dansk Pelsdyravl 1997b, 60, 440–442.
- Kupper LL, McMichael AJ, Symons MJ, Most BM. On the utility of proportional mortality analysis. J. Chron. Dis. 1978;31:15–22. doi: 10.1016/0021-9681(78)90077-2. [DOI] [PubMed] [Google Scholar]
- Miettinen OS, Wang J-D. An alternative to the proportionate mortality ratio. Am. J. Epidemiol. 1981;114:144–148. doi: 10.1093/oxfordjournals.aje.a113161. [DOI] [PubMed] [Google Scholar]
- Park MP, Maizlish NA, Punnett L, Moure-Eraso R, Silverstein MA. A comparison of PMRs and SMRs as estimators of occupational mortality. Epidemiology. 1991;2:49–59. doi: 10.1097/00001648-199101000-00008. [DOI] [PubMed] [Google Scholar]
- SAS Institute Inc: SAS Technical Report P-243, SAS/STAT Software: The GENMOD Procedure, Release 6.09, Cary, NC: SAS Institute INC., 1993.88 pp.
- Vaillancourt J-P, Stein TE, Marsh WE, Leman AD, Dial GD: Validation of producer-recorded causes of preweaning mortality in swine. Prev.Vet.Med. 1990, 10, 119–130.
- Vaillancourt J-P, Marsh WE, Dial GD. Internal consistency of preweaning mortality data collected by swine producers. Prev.Vet.Med. 1992;14:115–128. doi: 10.1016/0167-5877(92)90089-X. [DOI] [Google Scholar]