title: Cow-specific risk factors for clinical mastitis in Brazilian dairy cattle.
abstract: Information related to mastitis risk factors is useful for the design and implementation of clinical mastitis (CM) control programs. The first objective of our study was to model the risk of CM under Brazilian conditions, using cow-specific risk factors. Our second objective was to explore which risk factors were associated with the occurrence of the most common pathogens involved in Brazilian CM infections. The analyses were based on 65 months of data from 9,789 dairy cows and 12,464 CM cases. Cow-specific risk factors that could easily be measured in standard Brazilian dairy farms were used in the statistical analyses, which included logistic regression and multinomial logistic regression. The first month of lactation, high somatic cell count, rainy season and history of clinical mastitis cases were factors associated with CM for both primiparous and multiparous cows. In addition, parity and breed were also associated risk factors for multiparous cows. Of all CM cases, 54% showed positive bacteriological culturing results from which 57% were classified as environmental pathogens, with a large percentage of coliforms (35%). Coagulase-negative Staphylococcus (16%), Streptococcus uberis (9%), Streptococcus agalactiae (7%) and other Streptococci (9%) were also common pathogens. Among the pathogens analyzed, the association of cow-specific risk factors, such as Zebu breed (OR=5.84, 95%CI 3.77-10.77) and accumulated history of SCC (1.76, 95%CI 1.37-2.27), was different for CM caused by Coagulase-negative Staphylococcus and S. agalactiae in comparison to CM caused by coliforms. Our results suggest that CM control programs in Brazil should specially consider the recent history of clinical mastitis cases and the beginning of the lactations, mainly during the rainy season as important risk factor for mastitis.
authors: Department of Preventive Veterinary Medicine, Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627 Belo Horizonte, Minas Gerais, Brazil; Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Utrecht 3584 CL, The Netherlands.
authors: C S F
authors: CS
authors: Oliveira
authors: Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Utrecht 3584 CL, The Netherlands.
authors: H
authors: H
authors: Hogeveen
authors: Rehagro, Av. Uruguai 620, 30310-300 Belo Horizonte, Minas Gerais, Brazil.
authors: A M
authors: AM
authors: Botelho
authors: Rehagro, Av. Uruguai 620, 30310-300 Belo Horizonte, Minas Gerais, Brazil.
authors: P V
authors: PV
authors: Maia
authors: Department of Animal Science, Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627 Belo Horizonte, Minas Gerais, Brazil.
authors: S G
authors: SG
authors: Coelho
authors: Department of Preventive Veterinary Medicine, Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627 Belo Horizonte, Minas Gerais, Brazil. Electronic address: jphaddad01@globo.com.
authors: J P A
authors: JP
authors: Haddad
mesh_terms: D000818:Animals; D001938:Brazil / Q000453:epidemiology; D002417:Cattle; D003612:Dairying; D004755:Enterobacteriaceae / Q000302:isolation & purification*; D004756:Enterobacteriaceae Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D005260:Female; D007774:Lactation; D008137:Longitudinal Studies; D008414:Mastitis, Bovine / Q000453:epidemiology* / Q000382:microbiology; D012189:Retrospective Studies; D012307:Risk Factors; D012621:Seasons; D013290:Streptococcal Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D013291:Streptococcus / Q000302:isolation & purification*
keywords: Brazilian dairy industry; Clinical mastitis; Pathogen; Risk factor