When a Normal-Looking Udder Hides Mastitis: Recognising Subclinical Mastitis in Buffaloes

A buffalo can appear clinically normal while mastitis is already affecting the udder and milk production. This is what makes subclinical mastitis (SCM) particularly difficult to recognise in routine herd management. 

Unlike clinical mastitis (CM), SCM does not produce noticeable udder or milk abnormalities, yet it can persist within the herd and contribute substantially to production and economic losses. In dairy animals, SCM has been reported to occur 15–40 times more frequently than CM, making its silent nature an important clinical concern^[1]. 

When the Udder Looks Normal but the Problem is Not 

The absence of visible changes does not mean the mammary gland is unaffected. 

Mastitis develops when microorganisms gain access to the mammary gland and multiply within the alveolar tissue. Neutrophils are recruited as part of the local response, but their activity can also contribute to epithelial cell damage. As infection progresses, damaged epithelial cells and dead neutrophils enter the milk, contributing to an increase in somatic cell count (SCC)^[2],[3],[4]. 

That means the clinical picture can remain deceptively quiet while changes are occurring within the mammary gland. 

Why Should Vets Take Subclinical Cases Seriously? 

SCM is not simply a milder form of mastitis that can be ignored until visible signs appear. 

The condition has been associated with greater financial losses than CM, largely because production losses can continue without being immediately recognised^[5]. 

The economic impact can become substantial over a lactation. SCM has been associated with 100–500 kg of milk loss per lactating animal. Mastitis-related production losses have also been reported to be around three times higher with SCM than with CM, with SCM accounting for approximately 60–70% of mastitis-related losses^[4]. 

So, a buffalo that looks normal at milking may still be contributing to a gradual decline in herd productivity. 

Which Pathogens Can Be Involved?^[4] 

The microbial picture is not limited to one organism. 

Contagious pathogens such as Staphylococcus aureus and Streptococcus agalactiae, along with environmental organisms including Escherichia coli, Klebsiella pneumoniae, and Streptococcus uberis, have been associated with mastitis. Streptococcus dysgalactiae may have both contagious and environmental associations. 

Staphylococcus aureus and coagulase-negative staphylococci are also notable because they can persist within the udder and contribute to chronic infections that are difficult to manage. 

The Practical Point: Do Not Wait for Visible Mastitis^[4] 

The challenge with SCM is its lack of an obvious clinical signal. By the time milk or udder abnormalities become apparent, production losses may already have accumulated. 

For this reason, regular on-site screening can help identify animals requiring further evaluation and timely management. 

Tests such as SCC-based assessment and the California Mastitis Test (CMT) can support early detection by identifying changes associated with the mammary inflammatory response. 

Clinical Bottom Line 

A normal-looking udder does not rule out mastitis. In buffalo herds, SCM can remain clinically silent while affecting mammary health, milk production, and farm economics. Routine screening therefore has an important role in bringing these otherwise hidden cases into the clinical picture.

References:

1. Bhandari S, Subedi D, Tiwari BB, Shrestha P, Shah S, Al-Mustapha AI. Prevalence and risk factors for multidrug-resistant Escherichia coli isolated from subclinical mastitis in the western Chitwan region of Nepal. Journal of dairy science. 2021 Dec 1;104(12):12765-72. https://www.sciencedirect.com/science/article/pii/S0022030221004926
2. Viguier C, Arora S, Gilmartin N, Welbeck K, O’Kennedy R. Mastitis detection: current trends and future perspectives. Trends in biotechnology. 2009 Aug 1;27(8):486-93. https://www.academia.edu/download/79648544/mastitisreview-tibs.pdf
3. Teng TS, Ji AL, Ji XY, Li YZ. Neutrophils and immunity: from bactericidal action to being conquered. Journal of immunology research. 2017;2017(1):9671604. https://onlinelibrary.wiley.com/doi/pdf/10.1155/2017/9671604
4. Chowdhury MS, Rahman MM, Hossain H, Ghosh PK, Islam MR, Lamichhane B, Gomaa FA, Selim HM, Hossain MM, Helmy YA, El Zowalaty ME. Subclinical mastitis of buffaloes in Asia: prevalence, pathogenesis, risk factors, antimicrobial resistance, and current treatment strategies. Journal of Animal Science and Technology. 2026 Jan 31;68(1):18. https://pmc.ncbi.nlm.nih.gov/articles/PMC12923260/
5. Salvador RT, Beltran JM, Abes NS, Gutierrez CA, Mingala CN. Prevalence and risk factors of subclinical mastitis as determined by the California Mastitis Test in water buffaloes (Bubalis bubalis) in Nueva Ecija, Philippines. Journal of dairy science. 2012 Mar 1;95(3):1363-6. https://www.sciencedirect.com/science/article/pii/S0022030212000938