bActivate
Facilitate mare pregnancy

Problem getting your mare in foal?
bActivate finds the infection swabs miss.

In clinical series, 47 to 87% of problem mares carried a dormant uterine infection that the standard swab had missed. bActivate activates the dormant infections that standard tests miss, so your veterinarian can treat them and give barren mares a second chance.

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Key takeaways

  • What it does. bActivate is a sterile growth medium that re-activates dormant Streptococcus zooepidemicus, so a standard uterine culture taken 48 hours later finds the infection a swab missed. It is a diagnostic aid, not a treatment; the treatment is your veterinarian's, chosen from the antibiogram.
  • Who it is for. Problem mares: empty despite normal cycles, a fertile stallion and a clean swab, with two or more failed cycles, uterine fluid on ultrasound, early embryo loss, a previous endometritis, or age 10 and above. Seven questions: Is my mare a candidate?
  • Evidence. 64% activation-positive versus 8% with saline in the placebo-controlled study (Petersen et al., Veterinary Microbiology 2015). In the field series, 83% of 64 problem mares became pregnant at Hagyard 2014 and 89% of bred mares at Kildangan 2018; neither had a placebo group. All results.
  • How it is used. 10 ml instilled by your veterinarian in early oestrus (the first days of heat, before ovulation), culture after 48 hours, treatment on the antibiogram, breeding in the following cycle. Prescription veterinary product, 229 EUR per vial, minimum online order 2 vials. The protocol.

How bActivate works?

Dormant bacteria are difficult to diagnose by standard techniques and highly tolerant to antibiotic. Efficient handling thus requires re-activation of the bacteria. This can be achieved by instillation of bActivate, a bacterial growth medium, into the uterus.

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bActivate

What is bActivate?

bActivate is a bacterial growth medium capable of re-activating dormant streptococcal infections in the uterus of brood mares.

What bActivate is
Mare 1Mare 2
Application

When to use?

Some mares are still not pregnant at the end of the breeding season, despite fertile stallions and experienced veterinary supervision.

When to use it
Application

How to use?

bActivate is to be used in mares with reduced uterine defence mechanisms (the uterus's own ability to clear bacteria and fluid after breeding) and in mares suspected of having a chronic subclinical infection.

The protocol, step by step
ColtMare and foal
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Our products

The concept behind bActivate (promoting bacterial-activation) was discovered by Morten Rønn Petersen, DVM, PhD and Professor Anders Miki Bojesen, DVM, PhD.

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Who developed bActivate

Every season, some mares fail to get in foal. Now two Danish researchers have identified what might be wrong and produced a product, which can facilitate diagnostics. Veterinarians at the world's largest equine hospital in Kentucky have successfully tested the product.

Meet the founders

Product facts. bActivate is a sterile growth medium able to re-activate dormant bacteria, used as a diagnostic aid for the detection of latent endometritis in mares. One 10 ml vial, instilled by a veterinarian, with no antibiotics, hormones or live bacteria. It is a diagnostic aid, not a treatment; in the EU and UK it is not registered as a veterinary medicine, in the US it is a registered veterinary product. Evidence: Petersen et al., Veterinary Microbiology 2015 (placebo-controlled, 64% versus 8%); Hagyard 2014 (64 mares) and Kildangan 2018 (19 mares) field series, no placebo groups. Full facts and price on the what is bActivate page.

Continue reading

A clean swab is not a clean mare
Why a negative culture does not clear a problem mare
Swab vs biopsy vs bActivate
Detection rates of the three sampling options, side by side
Is my mare a candidate?
Seven questions, two minutes
Trusted by breeders & vets worldwide

What our clients say

Real results from veterinarians and breeders who have used bActivate on their most challenging problem mares.

Clinical Study
★★★★★

“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.”

KL
Dr. Kristina Lu, DVM
Hagyard Equine Medical Institute, Lexington, Kentucky
Clinical Study
★★★★★

“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.”

MO
Meta Osborne MVB CertESM MRCVS
Kildangan Stud, Godolphin
Breeder
★★★★★

“We have been using bActivate on several mares, all got pregnant and most of them in first try with frozen semen!”

JH
Jeanette Marina Hansen
Mare Owner & Breeder
Veterinarian
★★★★★

“bActivate is an excellent tool that allows us as reproductive vets to do our job effectively. It is both a smart and cost-effective solution in the long run.”

LB
Lotte Bøgedal
Reproductive Veterinarian
Breeder
★★★★★

“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.”

MD
Mary Davison
Cathrinestown Stud Farm, Leixlip, Ireland
Breeder
★★★★★

“Our 18-year-old mare had failed for five consecutive seasons. After bActivate she was confirmed strongly positive for Streptococcus, an infection standard testing had completely missed. She was treated, covered in September, and for the first time in five seasons there was no fluid present at ovulation. She is now 34 days in foal. This is the first time a pregnancy has not involved invasive flushing, excessive drugs and a battle to hold it.”

HG
Holly Graham-Jones
Mare Owner, Ireland

FAQ

Frequently Asked Questions

Common questions about problem mares, biofilm infections and bActivate activation.

What is bActivate?

bActivate is a bacterial growth medium used by veterinarians to reactivate dormant Streptococcus equi subsp. zooepidemicus infections in the uterus of problem mares. It reveals subclinical endometritis that standard tests fail to detect, so the veterinarian can diagnose accurately and treat with targeted antibiotics (an antibiotic chosen from the antibiogram, the laboratory's sensitivity test on the cultured bacteria).

Why can't my mare get in foal despite clean swabs?

In clinical series (Hagyard 2014, Kildangan 2018 and a University of Copenhagen thesis, 2025), 47 to 87% of problem mares carried a hidden uterine infection caused by dormant bacteria that the standard swab had missed. These bacteria enter a low-metabolic 'persister' state that evades standard uterine cultures and tolerates antibiotics. Standard swab culture has a detection sensitivity of about 34% (Nielsen 2005), so it misses most of these infections. bActivate reactivates the bacteria so they can be accurately diagnosed and treated by your veterinarian.

What is subclinical endometritis and why is it hard to detect?

Subclinical endometritis is a silent uterine inflammation with no visible symptoms: no discharge, no fever, no abnormal cycles. Despite appearing normal, the inflammation prevents embryo implantation. Because the bacteria are in a dormant, low-metabolic state, they are not picked up by routine swabs or culture tests.

What is a biofilm infection in a mare's uterus?

Biofilm is a protective layer that bacteria like Streptococcus zooepidemicus build around themselves inside the uterus. This shield makes them tolerant to antibiotics and undetectable by standard swabs. Biofilm infections are a major cause of chronic, treatment-resistant infertility in problem mares.

Why do antibiotics sometimes fail to cure uterine infections in mares?

When bacteria form biofilms or enter a dormant persister state, they tolerate antibiotics, even ones they are technically sensitive to, because the drugs target actively dividing cells. bActivate reactivates the bacteria first, making them metabolically active and vulnerable, so the veterinarian's targeted antibiotic treatment can work.

What are the signs of a hidden uterine infection in a mare?

Key signs include: repeated failure to conceive despite breeding to a fertile stallion, recurring uterine fluid detected on ultrasound, clean swab results combined with unexplained infertility, early embryo loss, and a history of multiple failed antibiotic treatments. If your mare shows these signs, dormant bacterial infection may be the cause.

How does bActivate work?

A veterinarian instills 10 ml of bActivate into the mare's uterus during early estrus. The growth medium reactivates dormant bacteria within 48 hours, making them detectable by standard culture. The veterinarian then prescribes targeted antibiotic treatment based on the culture result. Breeding is recommended in the following cycle.

Why does my mare lose her pregnancy so early?

Early embryo loss (before day 35) affects 10 to 15% of pregnancies and up to 30 to 40% in older or problem mares. A frequently overlooked cause is subclinical endometritis from dormant bacteria. The inflammation may not be severe enough to prevent conception, but it creates a hostile environment that ends the pregnancy in the first weeks. If your mare conceives but repeatedly loses her pregnancies, ask your vet about testing for dormant Strep. zooepidemicus with bActivate.

Can bActivate be used on older mares?

Yes. Older mares (10+ years) and mares with multiple previous foals are among the most common candidates for bActivate, as uterine defence mechanisms weaken with age. Clinical studies include a significant proportion of older problem mares with long histories of infertility.