title: Risk factors associated with Neospora caninum abortion in Ontario Holstein dairy herds.
abstract: The objective of this epidemiological study was to identify risk factors for Neospora caninum-related abortions in Ontario Holstein dairy herds. A total of 88 herds, consisting of 5080 cattle, and utilizing Dairy Herd Improvement (DHI) services, were divided into three groups. Case (n = 30) and first control (n = 31) herds were selected from 1998 and 1999 fetal abortion submissions to the Animal Health Laboratory, University of Guelph, that were histopathologically positive or negative, respectively, for N. caninum. A second control group (n = 27) was selected from multiple sources of herds sampled within the previous 4 years that had a low seroprevalence (<7%) to N. caninum. Between May and December 1999, all available cows on all farms, in parity one or greater, were blood sampled. The sera were then analyzed for antibody to N. caninum using a kinetic ELISA. A survey administered at the time of sampling recorded information on housing, animal species present, manure management, reproduction, biosecurity practices, wildlife observations, peri-parturient cow management, herd disease history and nutrition. Production and other herd parameters were obtained from DHI records. Logistic regression indicated that the following parameters were positively associated with a N. caninum abortion in a herd: the N. caninum herd seroprevalence (OR = 1.1), the total number of dogs on a farm (OR = 2.8), the frequency that dogs were observed defecating in mangers (OR = 2.8), the number of horses on a farm (OR = 3.1), the observed annual rate of retained fetal membranes (OR = 1.2) and the observed annual rate of cows returning to estrus after pregnancy confirmation (OR = 1.2). Factors negatively associated were the frequency of stray cats and wild canids observed on a farm (OR = 0.4 and OR = 0.7, respectively) and the housing of heifers on loafing packs (a housing pen divided into feed manger, scrape alley and bedded pack areas, OR = 0.1).
authors.affiliation: Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, Ont., Canada N1G 2W1. jchobson@uoguelph.ca
authors.forename: J C
authors.initials: JC
authors.lastname: Hobson
authors.forename: T F
authors.initials: TF
authors.lastname: Duffield
authors.forename: D
authors.initials: D
authors.lastname: Kelton
authors.forename: K
authors.initials: K
authors.lastname: Lissemore
authors.forename: S K
authors.initials: SK
authors.lastname: Hietala
authors.forename: K E
authors.initials: KE
authors.lastname: Leslie
authors.forename: B
authors.initials: B
authors.lastname: McEwen
authors.forename: A S
authors.initials: AS
authors.lastname: Peregrine
mesh_terms: D000034:Abortion, Veterinary / Q000453:epidemiology*; D000822:Animal Husbandry; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology*; D003048:Coccidiosis / Q000453:epidemiology / Q000662:veterinary*; D004197:Disease Reservoirs; D005260:Female; D018688:Neospora / Q000302:isolation & purification*; D016017:Odds Ratio; D009864:Ontario / Q000453:epidemiology; D011159:Population Surveillance; D012307:Risk Factors