bActivate is a bacterial growth medium used by veterinarians to reactivate dormant Streptococcus equi subsp. zooepidemicus infections in the uterus of problem mares. It enables accurate diagnosis and treatment of subclinical endometritis that standard tests fail to detect.

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

70–80% of problem mares carry a hidden uterine infection caused by dormant bacteria. These bacteria enter a low-metabolic 'persister' state that evades standard uterine cultures and resists antibiotics. Standard swabs miss this infection in over 60% of cases. bActivate reactivates the bacteria so they can be accurately diagnosed and treated.

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 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 resistant 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 become resistant to antibiotics — even ones they are technically sensitive to. Antibiotics cannot penetrate the biofilm shield effectively. bActivate reactivates the bacteria first, making them metabolically active and vulnerable to targeted antibiotic treatment.

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.

What pregnancy rates has bActivate achieved in clinical studies?

In a study at Hagyard Equine Medical Institute led by Dr. Kristina Lu, 83% of 64 problem mares became pregnant after bActivate treatment. At Kildangan Stud (Godolphin), 89% pregnancy rate was achieved in 19 problem mares. Copenhagen University data showed a 72% live foal rate. At Hagyard, 47% of treated mares tested positive for dormant Strep — infections that had been missed by prior standard testing.

When should bActivate be used?

bActivate is indicated for mares that have failed to conceive despite breeding to fertile stallions, mares with recurring uterine fluid, mares with previous uterine infections, older broodmares with reduced uterine defense, and mares where antibiotics have previously failed. It is administered during estrus, approximately 5 days before intended breeding in the next cycle.

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.

Is bActivate safe for mares?

Yes. bActivate has been tested extensively at leading equine hospitals including Hagyard Equine Medical Institute and Kildangan Stud (Godolphin). The infusion may cause a mild, temporary uterine reaction in heavily infected mares. Breeding in the same cycle as the activation is not recommended — the mare is bred in the following cycle after targeted antibiotic treatment.

Where can I buy bActivate in Europe?

bActivate is produced by Bojesen and Petersen Biotech ApS in Denmark and is available through authorised equine veterinary distributors across Europe and Australia. Contact us at contact@bactivate.eu or visit our shop page to order or find your nearest distributor.

Is my 14-year-old mare with 4 foals a candidate for bActivate?

Yes. A 14-year-old mare with 4 previous foals has two primary risk factors: age 12 or older, and 3 or more previous foals. Mares with one or more risk factors have approximately 75% probability of carrying a dormant Streptococcus zooepidemicus infection that standard endometrial swab culture cannot detect. bActivate is strongly indicated before the next breeding cycle.

My mare has a clean swab but keeps coming back into season — is she a candidate?

Yes, possibly. Standard endometrial swab cultures detect only approximately 33% of infections when one is present. If your mare has one or more risk factors (age 12+, 3+ foals, abortion history, prior endometritis) and has failed to conceive for two or more consecutive cycles, bActivate is strongly indicated even with clean swabs.

Is a mare with a history of endometritis a candidate for bActivate?

Yes. A history of endometritis is one of the four primary risk factors. Mares treated for endometritis in the past are at high risk of carrying a dormant persister-state Streptococcus zooepidemicus infection that standard swabs cannot identify and antibiotics cannot reach.

What are the 4 risk factors for dormant uterine infection in problem mares?

The four risk factors are: (1) age 12 years or older; (2) three or more previous foals; (3) a history of abortion or pregnancy loss; and (4) a documented previous episode of endometritis. Mares with one or more factors have approximately 75% probability of dormant Streptococcus zooepidemicus infection.

Can a young maiden mare be a candidate for bActivate?

Yes, though probability of dormant infection is lower than in high-risk mares. If a maiden mare has failed to conceive for two or more consecutive cycles with negative swabs and a fertile stallion, bActivate should be discussed with your veterinarian.

Mare assessment

Is my mare a candidate
for bActivate?

Answer 7 questions about your mare. The assessment takes about 2 minutes and gives you a personalised risk profile based on the clinical criteria used by veterinarians.

Question 1 of 7 0%

How old is your mare?

Age is the strongest single predictor of dormant uterine infection.

Under 10 years 10–11 years 12–15 years risk factor 16 years or older risk factor

How many foals has she had?

Each pregnancy reduces uterine defence capacity over time.

None — maiden mare 1–2 foals 3 or more foals risk factor

Has she had an abortion or pregnancy loss?

Including early embryonic death or loss before day 50.

Yes risk factor No

Has she been diagnosed with endometritis?

Any previous episode — treated or untreated.

Yes risk factor No Not sure

How many cycles has she failed to conceive?

Counting from when you first started trying this season or across seasons.

This is the first season — still early 2–3 consecutive cycles 4 or more — or multiple seasons

What have her endometrial swabs shown?

Standard culture from cytobrush or low-volume lavage.

Positive — bacteria detected Negative — clean result Not tested yet

Has she had uterine fluid on ultrasound?

Fluid detected post-breeding or during oestrus on rectal ultrasound.

Yes — fluid detected No — uterus clear Not checked

Example profiles

14-year-old, 4 foals, clean swabs, 3 failed cycles

2 risk factors (age 12+, 3+ foals) → HIGH RISK — ~75% probability of dormant infection. bActivate strongly indicated.

10-year-old, 2 foals, prior endometritis, clean swab

1 risk factor (endometritis history) → HIGH RISK — clean swab does not rule out infection. bActivate indicated.

12-year-old, 3 foals, abortion 2022, uterine fluid on scan

3 risk factors → HIGH RISK — very high probability. bActivate strongly indicated before next breeding cycle.

8-year-old maiden, no prior issues, 2 failed cycles

0 risk factors → Standard risk. After 2+ failed cycles with clean swabs, bActivate should be discussed with your veterinarian.

The 5-step bActivate protocol

What happens at each stage

Clinical results

83% pregnancy rate in 64 problem mares at Hagyard

Glossary

Dormant persister cell, biofilm, high-risk mare and more

Order bActivate

Available through veterinary distributors worldwide

FAQ

Frequently Asked Questions

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

Is my mare a candidatefor bActivate?