Mycoplasma mastitis in cattle: To cull or not to cull

• Mycoplasma mastitis, caused mainly by Mycoplasma bovis, is a serious disease of cattle, mainly in large dairy herds.
• Mycoplasma disease is mostly untreatable, although often self-limiting.
• Early diagnosis and separation of affected cows is essential to prevent spread in the herd.
• Risk factors include increasing herd size, introduction of cattle and absence of hospital pens.
• Owners should consider purchase of replacement only from M. bovis-free herds.

Bovine mastitis caused by mycoplasmas, in particular Mycoplasma bovis, is a major problem for milk production and animal welfare in large dairy herds in the USA and a serious, although sporadic, disease in Europe and the Middle East. It causes severe damage to the udder of cattle and is largely untreatable by chemotherapy. Mycoplasma mastitis has a distinct epidemiology and a unique set of risk factors, the most important of which is large herd size. The disease is often self-limiting, disappearing within months of outbreaks, sometimes without deliberate intervention. Improved molecular diagnostic tests are leading to more rapid detection of mycoplasmas. Typing tests, such as multi-locus sequence typing, can help trace the source of outbreaks. An approach to successful control is proposed, which involves regular monitoring and rapid segregation or culling of infected cows. Serious consideration should be given by owners of healthy dairy herds to the purchase of M. bovis-free replacements. Increased cases of disease could occur in Europe and Israel if the trend for larger dairy herds continues.