Case control study of risk factors for toxic mastitis in 26 dairy herds

Abstract

A retrospective case control study of farm level risk factors for toxic mastitis was carried out in November and December 1996. Twenty-six farms from mid-Somerset were visited: 13 case farms (had had a cow with toxic mastitis in the previous year) and 13 geographically matched controls (no case of toxic mastitis). The farmers were interviewed and the buildings were examined. Information was collected on the type and quality of housing, usual milking routines, milk quality and mastitis prevalence in the previous year. All the data were collected on to pretested recording sheets and loaded into a database. Simple and complex analysis was done. The following variable were significantly (P < 0.05) associated with an increased risk of toxic mastitis in the simple analysis: housing cows in October rather than November; a low number of calving boxes per cow; a high proportion of cows with intermediate body condition and low herd bulk milk somatic cell counts (HBMSCC). In the final model low HBMSCC and a high proportion of cows with intermediate body condition remained significant. The authors conclude that, despite the small size sample, the results of this study are consistent, plausible and support the information from previous experimental and observational studies about the role of somatic cell counts in toxic mastitis.

Aetiology of clinical mastitis in six Somerset dairy herds

“…The mortality and fatality rates recorded were higher than in previous reports (Blowey 1986, Wilesmith and others 1986, Kossaibati and others 1998) and may possibly be explained by the relatively higher incidence of coliform mastitis. The high incidence of more severe mastitis (grades 2 and 3) in the herd with the lowest cell count also agrees with the findings of previous studies (Green and others 1996, Barkema and others 1998, Tadich and others 1998), and provides more evidence that the continued reduction of somatic cell counts may predispose cows to more severe mastitis, with clear welfare implications. The fact that the herd which was kept indoors throughout the year had significandy more severe mastitis, and the trend towards more severe E coli mastitis between October and March may have been due to a number of factors associated with housing, such as dietary changes (Hogan and others 1993) and the stress associated with close confinement.…”

Study of clinical mastitis in British dairy herds with bulk milk somatic cell counts less than 150,000 cells/ml

“…The cows with SCCs of up to 40,000 cells/ml in the month before a case of clinical mastitis were more likely to suffer a severe rather than a mild case of clinical mastitis than cows with higher SCCs. Studies by Green and others (1996) and Tadich and others (1998) have observed a positive association between a low BMSCC and the risk of toxic mastitis. Experimental studies have demonstrated a negative association between the severity of an infection and the individual cow SCC before the infection (Shuster and others 1996, Schukken and others 1999, van Werven 1999).…”

Invited review: Low milk somatic cell count and susceptibility to mastitis

“…In a herd monitored for infections for 12 yr, low SCC (<200,000 cells/mL) was associated with a higher risk of severe clinical mastitis (Suriyasathaporn et al, 2000). Several studies have suggested that clinical mastitis was more severe in low SCC herds or in cows with low SCC (Green et al, 1996;Barkema et al, 1998;Tadich et al, 1998). Although several factors may contribute to these observations, such as a higher proportion of infections by gram-negative bacteria, they could be interpreted as resulting in part from a decreased capacity of cows to control MG infections when their milk SCC is low.…”