Dairy Cow Mastitis: Prevention, Treatment, and Welfare

Mastitis: The Most Costly Disease in Dairy Farming

Mastitis — inflammation of the mammary gland, usually caused by bacterial infection — is the most economically important and welfare-significant disease in dairy cattle globally. In the UK alone, approximately 25% of dairy cows experience clinical mastitis annually, causing significant pain, reduced productivity, and premature culling. Effective prevention and treatment programmes are both a welfare and economic priority.

Types and Causes

Clinical mastitis: Visible signs — abnormal milk (clots, watery secretion, blood), swollen, hot, painful quarter, and often systemic signs (fever, reduced appetite, reduced milk yield). Ranges from mild (abnormal milk only) to severe (systemic illness requiring intensive treatment).

Subclinical mastitis: No visible signs but elevated somatic cell count (SCC) reflecting inflammation. Causes reduced milk yield and quality. Identified by SCC monitoring — individual cow SCC above 200,000 cells/ml is diagnostic.

Key pathogens:

• Streptococcus uberis: Environmental pathogen; common cause of clinical mastitis
• Staphylococcus aureus: Contagious pathogen spread at milking; difficult to cure; managed by culling chronic cases
• Escherichia coli: Environmental pathogen; often severe acute disease; responds to anti-inflammatory treatment
• Streptococcus agalactiae: Contagious; eradicable through test-and-cull programmes

Welfare Impacts

Clinical mastitis causes genuine suffering — the inflamed quarter is painful on palpation and during milking. Severe coliform mastitis causes septic shock, recumbency, and without aggressive treatment, death. Cows with clinical mastitis show reduced feed intake, reduced lying time (pain during udder contact with ground), and altered behaviour indicating pain. Pain scoring and analgesic use should be standard in mastitis management protocols.

Treatment Principles

Treatment should be prompt, targeted, and welfare-oriented:

• Bacteriological culture guides antibiotic selection — ideally before treatment or from the first case in an outbreak
• NSAIDs (meloxicam, flunixin) provide pain relief and reduce inflammation — welfare-essential addition to all moderate-severe cases
• Oxytocin administration and frequent stripping supports milk let-down and removal of infected material
• Supportive care (IV fluids, glucose) for severe coliform cases
• Culling decisions for chronic, untreatable cases (Staph. aureus, recurrent clinical) balance welfare and economics

Prevention Strategy

The '5-point mastitis control plan' remains the foundation: effective milking machine function, teat disinfection post-milking, dry cow therapy (selective or blanket), culling of chronically infected cows, and good record-keeping. Vaccination (Startvac for E. coli/Staph. aureus) provides supplementary protection in high-risk herds.

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