Saving Time and Money with bActivate: A Smarter Approach to Endometritis in Mares
For many horse breeders, a mare that repeatedly fails to conceive represents a significant financial and emotional burden. A single breeding season at a warmblood or thoroughbred stud can cost thousands of euros in covering fees, veterinary examinations, pregnancy testing and housing. When that investment yields a barren mare, the pressure to diagnose and solve the problem quickly is intense.
The standard diagnostic pathway — uterine swab, culture, antibiotics — sounds straightforward. In practice, it frequently fails because the most common cause of chronic mare infertility, dormant Streptococcus zooepidemicus, is invisible to standard culture techniques and resistant to antibiotic treatment in its dormant state.
The Hidden Cost of Missed Diagnosis
Consider a typical scenario: a mare returns a culture-negative swab. The veterinarian, seeing no bacteria, clears her for breeding. She is covered, fails to hold a pregnancy, and the cycle repeats. By the end of the season, the breeder has paid for:
- Multiple covering fees (often €1,000–5,000+ per attempt in warmblood breeding)
- Repeated veterinary examinations and ultrasounds
- Antibiotic courses that provide temporary improvement but no lasting resolution
- A lost season — the mare produces no foal, no income, no genetic progress
Research indicates that 50–75% of mares that remain open at the end of the breeding season are chronically infected with dormant bacteria. This is not a rare edge case — it is the most likely explanation for a mare that cycles normally but fails to get in foal.
Why the Standard Approach Is Expensive by Design
The problem with treating endometritis using the conventional detect-and-treat approach is that it targets only the bacteria that are already active and detectable. Dormant persister cells — the subpopulation embedded deep in the endometrial mucosa — survive antibiotic treatment, repopulate during the next oestrus cycle, and trigger another round of inflammation.
This creates a pattern of apparent short-term success (fluid clears, swab goes negative) followed by renewed infertility. The breeder invests in another season. The cycle continues.
Prof. Anders Miki Bojesen, Professor of Veterinary Microbiology at the University of Copenhagen, has described this mechanism in peer-reviewed research: dormant streptococcal cells form biofilm-protected colonies within the uterine mucosa that are not reached by systemic or intrauterine antibiotics at standard doses.
The Economic Case for Activate-First
The bActivate protocol introduces a single diagnostic step before antibiotic treatment: reactivation. A veterinarian instils 10 ml of bActivate into the uterus during early oestrus. Within 48 hours, dormant bacteria wake up, begin multiplying, and become detectable by standard culture. The culture result now reflects the actual infection — not just the fraction of bacteria that happened to be active on the day of the swab.
This changes the economics of treatment fundamentally:
- One diagnostic step replaces multiple inconclusive swabs
- Targeted antibiotic treatment based on a real culture result is more effective than empirical broad-spectrum therapy
- Treatment in one cycle followed by breeding in the next cycle
- 83% pregnancy rate in problem mares at Hagyard Equine Medical Institute (64 mares, Dr. Kristina Lu)
- 89% pregnancy rate at Kildangan/Godolphin Stud in Ireland (19 thoroughbred mares)
For a mare that has been barren for two or three seasons, a single bActivate treatment cycle costing a fraction of a covering fee is a straightforward economic decision.
How to Use bActivate in Your Breeding Programme
bActivate is a prescription veterinary product. Your veterinarian will assess whether your mare is a suitable candidate based on her reproductive history. The protocol is performed during a normal oestrus cycle approximately one cycle before the intended breeding.
Mares most likely to benefit include those with:
- Repeated failure to conceive despite normal cycles
- Culture-negative swabs combined with unexplained infertility
- A history of recurrent uterine fluid on ultrasound
- Previous antibiotic treatment without lasting improvement
- Multiple barren seasons in mares aged 8 years or older
If your mare fits this profile, read more about when bActivate is indicated or find your nearest bActivate distributor.
Written by the Bojesen & Petersen Biotech ApS team. Medical oversight: Prof. Anders Miki Bojesen DVM PhD (University of Copenhagen) and Dr. Morten Rønn Petersen DVM PhD Dipl. ACT (Rigshospitalet).
What our clients say
Real results from veterinarians and breeders who have made bActivate part of their reproductive protocol.
“We incorporated bActivate into our standard reproductive work-up for problem mares at Hagyard. Out of 64 mares that had failed to conceive for at least 3 cycles, 83% became pregnant following bActivate activation and targeted antibiotic treatment. Nearly half had a dormant Streptococcus infection that standard culture had completely missed. It changed the way we approach the problem mare.”
“We used bActivate on 19 of our most persistent problem mares — horses that had been barren for over a year despite every conventional treatment we tried. 89% of them got in foal. What really opened our eyes was how many had a hidden infection that standard swabs had never detected. It is now a routine part of our protocol at Kildangan.”
“We have been using bActivate on several mares — all got pregnant and most of them in first try with frozen semen!”
“bActivate is an excellent tool that allows us as reproductive vets to do our job as effectively as possible. When you compare the cost to the expense of a mare that fails to conceive — or worse, never produces a foal — bActivate is both a smart and cost-effective solution in the long run.”
“I used bActivate and after just one covering got a colt foal — after 3 years of hardship where the mare went in foal but never managed to produce a live foal. I cannot recommend bActivate enough.”