You know the number, but it’s worth restating: a case of clinical mastitis in the first 30 days of lactation can cost you up to $444. While preventing mastitis is often the focus, how well do you truly understand the pathogens responsible for it? What are the real effects on the cow, and are your efforts to manage it really making a difference?
Mycoplasma bovis is considered the most prevalent and clinically important mycoplasma species in dairy cattle. Infected animals shed high levels of this organism, easily contaminating the environment around them, such as the milking parlor, free stalls, and more. Clinical signs that typically follow infection with M. bovis include swelling of the whole udder or individual quarters, severe mastitis in otherwise healthy cows, abnormal udder secretions, multiple affected quarters, decreased milk production in affected quarters, prolonged milking times, and a lack of response to antimicrobial treatment.
A threat beyond mastitis
M. bovis is resistant to antibiotics, partially due to its lack of a cell wall. It has the ability to disseminate to different body sites, causing clinical signs beyond mastitis, such as arthritis and pneumonia. Not only does this impact the infected cow, but it also makes the spread of the organism even more likely as it can be shed from multiple body sites.
The high cost of M. bovis
The economic loss due to M. bovis mastitis alone is estimated to be more than $108 million annually in the U.S. As with Staph aureus, the most effective way to prevent disease caused by M. bovis is a rigorous screening protocol. Subclinical infections pose the largest risk to herd outbreaks. Success in reducing M. bovis infection rates depends heavily on the ability to identify and segregate infected cows early. Screening purchased cows and heifers before they enter the herd, as well as fresh and newly infected high somatic cell count (SCC) cows is crucial.
Screening is the first step to monitor and manage infections
Monthly testing of bulk tank samples for M. bovis can be a great way to monitor the herd overall. The increased sensitivity of PCR reduces the risk of missing low-level infections, even in larger herds. The turnaround time for mycoplasma culture is typically 1-2 weeks. PCR reduces that turnaround time to just a couple of days, allowing for faster on farm action. Identification and removal of infected animals is the best way to avoid widespread outbreaks. The criteria for determining which cows to test individually is often herd-specific. While some choose to test their entire herd at one time for rapid response, others take a more gradual approach by only testing certain high-risk groups (such as fresh cows) or based on high SCC.
Any of these options can be successful if combined with proper management strategies for positive cows. Because M. bovis contaminates the environment so easily, spreads throughout the body, and infects animals of all ages, it can be nearly impossible to completely eradicate. Proactive monitoring, even when everything seems to be going well, is the key to success.
Sources:
https://www.vet.cornell.edu/animal-health-diagnostic-center/testing/testing-protocols-interpretations/mycoplasmal-mastitis
https://www.sciencedirect.com/science/article/pii/S2666517422000207?via%3Dihub