When to Use bActivate for Problem Mares
bActivate – a diagnostic aid for the problem mare
bActivate can help establish a correct diagnosis in the chronically infected mare. bActivate initiates growth of resident dormant streptococci, which can then be diagnosed and treated by standard techniques.
Chronic infections prevent establishment of a pregnancy, and might also increase the risk of early fetal loss and abortion in the mare. Our studies indicate that 50-75% of problem mares not pregnant by the end of the breeding season, despite breeding to fertile stallions and supervised by experienced veterinarians, are chronically infected.
Some farms use bActivate as a screening tool to improve diagnosis of endometritis and treatment on all open mares during the off-season, hereby optimizing chances to establish a pregnancy and reduce time to pregnancy.
Repeated uterine infections indicate compromised uterine defense mechanisms predisposing for establishment of infections – acute as well as chronic. As chronic infections can be hard to identify bActivate should be considered for this group of problem mares.
Endometrial fibrosis is induced by ongoing endometrial inflammation. Presence of beta-hemolytic streptococci within the endometrium is expected to induce endometrial inflammation, hereby increasing uterine fibrosis, and consequently decreasing fertility. If endometrial fibrosis can be minimized the number of foals each mare can produce in a lifetime is expected to increase.
Is My Mare a Candidate for bActivate?
bActivate is indicated for mares with reduced uterine defence mechanisms and suspected chronic subclinical infection. Use the checklist below as a starting point when discussing with your veterinarian.
Strong indications
- ✓Mare has failed to conceive for two or more consecutive seasons despite breeding to a proven fertile stallion
- ✓Culture-negative swabs combined with unexplained infertility or recurrent uterine fluid on ultrasound
- ✓Previous antibiotic treatment resolved fluid temporarily but fertility did not improve
- ✓History of early embryo loss (before day 15) in multiple seasons
Consider bActivate when
- ✓Mare is 10 years or older with a history of uterine infections or fluid accumulation
- ✓Mare has had repeated bacterial isolations (Strep zoo, E. coli) over multiple seasons
- ✓Mare is an open mare at end of season entering the off-season with no pregnancy
- ✓Mare has documented endometrial fibrosis (category IIB or III) and compromised uterine clearance
bActivate is a prescription veterinary product. Your veterinarian will assess suitability based on reproductive history, clinical examination and ultrasound findings.
Which Mares Benefit Most?
Dormant streptococcal infections can affect mares across all breeds and ages, but certain groups are disproportionately represented in clinical case populations.
Older Broodmares
Uterine defence mechanisms decline with age and parity. Mares aged 10+ with multiple previous foalings have reduced mucociliary clearance and lymphatic drainage, making them more susceptible to persistent infection. Clinical studies include a significant proportion of older mares with long histories of infertility.
Thoroughbred & Sport Horses
High-value thoroughbred and warmblood mares where the economic cost of a missed season is significant. The Kildangan/Godolphin study demonstrated an 89% pregnancy rate in 19 barren thoroughbred problem mares after a single bActivate treatment cycle.
Repeat Breeders
Mares that cycle normally, accept covering, and produce embryos that consistently fail to implant. The inflammatory environment created by dormant Strep zoo prevents uterine preparation for implantation even when the embryo itself is viable.
When in the Breeding Season to Use bActivate
The bActivate protocol is designed to fit within a normal breeding cycle. Treatment takes place approximately one cycle before the intended breeding cycle.
Total time from bActivate administration to breeding-ready: 3–4 weeks. This fits within a standard 21-day oestrous cycle, meaning a single treatment cycle before the target breeding cycle.
Off-Season Screening
Some breeding operations use bActivate as a proactive screening tool for all open mares at the end of the season or during the winter off-season. This approach offers several advantages:
- ✓Identifies chronic infections before the next breeding season begins
- ✓Allows a full treatment and recovery cycle without time pressure
- ✓Reduces time to pregnancy at the start of the next season
- ✓Minimises wasted covering cycles on untreated infections
- ✓Particularly valuable for high-value mares where early-season pregnancy is economically important
- ✓Helps farms plan breeding schedules with greater confidence
Our studies indicate that 50–75% of mares that remain open at the end of the breeding season are chronically infected. Off-season screening with bActivate addresses this directly.
The concept behind bActivate (promoting bacterial-activation) was discovered by Morten Rønn Petersen, DVM, PhD and Professor Anders Miki Bojesen, DVM, PhD. They both have extensive experience with bacterial endometritis in mares and have published several scientific papers on the subject.
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.”