I was at the Canadian Dairy XPO this year having some great mastitis conversations with progressive producers. In my biased sample of interactions, there were generally two strategies when I asked how they treated mastitis: either treat everyone or treat no one. Both approaches are understandable, but neither is optimal.
Let me explain. Mastitis is an incredibly complex syndrome, caused by a massively diverse group of bugs with nearly an equal number of management, cow and environmental risk factors. We have been studying it for about as long as we have been milking cows, yet every single paper written on mastitis contains some variation of the phrase: “Mastitis is among the costliest diseases in dairy production.” If this sentence hasn’t changed, perhaps the problem isn’t just the condition; maybe it is how we make decisions about it.
The problem with reductionist, binary thinking
This is 2026. The amount of data being generated on our dairy farms is at a level never-before-seen. There are operations with minute-by-minute activity and rumination monitors, milking-level production and health data, and precision automated feeding technologies (to name a few). So why are we still treating mastitis the same way we did when I was born? (FYI, I’m old and bald.)
For instance, the “treat ‘em all” strategy exists for a reason. It maximizes bacteriological cure of clinical mastitis. Cows with mastitis deserve cures, as this is a welfare and productivity concern. This practice does raise very valid concerns:
- Treating everyone has a cost – in terms of drugs, labour and milk discard.
- We are overtreating a significant proportion of cases that would have self-cured (no growths, mild/moderate gram-negative infections, some non-aureus staph) or have a very low odds of cure (e.g., S. aureus, prototheca). Example: Did you know that studies report 20% to 40% of mastitis cases will return culture negative results? The science is clear on these cases – there is little to gain from treating with antibiotics.
- Antimicrobial use in agriculture is under increased scrutiny due to concerns over potentially promoting antibiotic resistance. Antibiotic stewardship involves using as much as necessary, as little as required.
Moving on to the “I treat nothing” camp. I can also completely understand and sympathize with this philosophy. Clinical and bacteriological cures for cows with mastitis can be extremely disappointing, especially if we do not have information on the bug that caused the mastitis. The benefits of using no intramammary antibiotics are a huge reduction in antimicrobial use which, in turn, can be a “good news” story about reducing the selection for antimicrobial resistance. I have some serious concerns with this approach as well:
- We may be missing some real cure opportunities in many cows.
- Without treatment, susceptible bugs could produce chronic high-SCC cows and lead to clinical recurrence.
- With chronic infections, there are hidden long-term production, welfare and reproduction losses that can significantly impact the efficiency of your organization.
Both strategies assume a homogeneity of mastitis – that all cases are created equally. This can be logically seductive, but it is biologically false.
When the tractor won't start: Mastitis isn't (really) one problem
Everyone has been there. You wake up refreshed and recharged: cows to milk, feed to push, the world to feed for another day. You hop in the tractor, turn the key, and … nothing. Won’t start. Raise your hand if you would just throw a new battery in there every time that happens.
I’m going to assume there are no hands raised. Of course not. Yes, it could be the battery, but it could also be the fuel system, starter, wiring, any number of electrical issues, etc. Any qualified mechanic would start with running diagnostics and physical checks before deciding how to fix it.
Mastitis is a very similar beast – when we’re looking at a cow with mastitis, we see abnormal milk, a swollen udder and maybe a sick cow. This is looking at mastitis like the syndrome that it is. This is analogous to the tractor that won’t start. To properly treat and manage that cow, we need to look under the hood. A Streptococcus uberis infection, a Staphylococcus chromogenes infection, a yeast infection – they can all look the same – but they are far from the same problem. If we treat them all in the same manner, we shouldn’t be surprised when the results are not consistent.
Looking under the hood: Should you reach for antibiotics?
Mastitis is a syndrome: The result of the convergence of many risk factors with the exposure of the mammary gland to one or more bacteria. When we decide what is to be done with any case of mastitis, we need more than “I see clots.” We need information.
Age, stage of lactation, season of the year, somatic cell count (SCC) and mastitis history, other diseases present, number of quarters infected, severity of the infection – all these factors inform how successful we may be in treating a cow. Looking at these factors before treatment is like your mechanic helping you decide whether the tractor is a write-off.
Next, just like our mechanic friend, we run diagnostics. Historically, this has involved sending samples to the vet clinic or lab and waiting. When we understand what bug is causing mastitis, we can integrate this information with the cow factors to determine whether this cow is a good candidate for antibiotic therapy. Is it a first-lactation cow, single-quarter affected, mild case, low SCC the month before, with Streptococcus dysgalactiae diagnosed? She would be a good candidate for antibiotic therapy. Fifth-lactation cow who’s had high SCC for the past three months and a Staphylococcus aureus diagnosis? Cure potential is very, very low.
What's new with rapid identification of mastitis pathogens
I have spent most of my career in a love-hate relationship with mastitis – I love to hate it! In that journey, I have searched high and low for practical solutions that can give us timely answers on the pathogen causing mastitis.
Historically, obtaining that information meant collecting a sample, shipping it to a laboratory and waiting several days for results. While laboratory culture remains an important tool, the landscape is changing rapidly. Many veterinary clinics and diagnostic laboratories now offer mastitis culture results within 24 hours, helping bridge the gap between diagnosis and treatment decisions. Research shows that for non-severe cases, waiting 24 hours to treat does not affect your success.
At the same time, a growing number of on-farm diagnostic options are emerging. Chromogenic culture systems, automated platforms, portable PCR and other rapid diagnostic tools are bringing information closer to the cow than ever before. Each approach has strengths and limitations, but all share a common goal: helping producers make more informed decisions.
The future of mastitis management is not treating every cow. It is not treating any cows. It is recognizing that mastitis is a syndrome with many possible causes, each requiring a tailored response. The best mastitis programs of the future will use information more effectively. After all, when the tractor won't start, nobody reaches for a wrench before looking under the hood.
