The purpose of this study was to describe the prevalence and incidence of Neospora caninum infection in dogs that are in close contact with dairy cattle and to identify possible risk factors associated with the infection in this population. Twenty-four dogs located in 8 different dairy farms of Aguascalientes, Mexico, were evaluated for a 6-mo period. Once a month a sample of serum and a sample of peripheral blood was collected. The serum was used to detect antibodies against N. caninum by means of the indirect immunofluorescence technique, and the blood was used to detect parasite's DNA. The association between seroprevalence and possible risk factors was estimated using logistic regression. The prevalence of anti-N. caninum antibodies was 54% in the first month, 62% in the last month, and the incidence was 8.69%. One farm had no positive cases. Antibody titers ranged from 1:50 to 1:800. Parasite DNA was not detected in any of the samples. Only the age (>6 yr) of the dogs was identified as a risk factor for infection by N. caninum (P ≤ 0.05).