Nearly a Third of Breeders Give Antibiotics Around Breeding — Often Based on Test Results Alone
If you breed dogs, you may have heard that getting a vaginal culture before breeding is a good idea. A culture is a lab test that checks for bacteria in the reproductive tract. But a new survey published in Frontiers in Veterinary Science raises a concern worth knowing: routine vaginal cultures in breeding dogs are strongly linked to antibiotic use — even when the dog shows no signs of illness.
The survey asked 426 dog breeders about their practices. Nearly one in three — 32% — reported giving antibiotics around the time of breeding. And the biggest predictor of antibiotic use was whether a vaginal culture had been done and had come back showing bacteria. The problem? Finding bacteria doesn’t automatically mean a dog is sick or needs treatment.
Why Bacteria Aren’t Always the Enemy
It can be easy to assume that any bacteria found on a test means there’s a problem. But dogs — like people — naturally carry bacteria in and around their reproductive systems. These microbes are often normal residents that do no harm.
Think of it like finding dust in your house. Some dust is expected and harmless. Only certain types in large amounts, or paired with symptoms like sneezing or allergies, become a real problem. The same logic applies to bacteria in a dog’s vaginal tract.
The concern highlighted by this study is that a positive culture — one that finds bacteria — can trigger antibiotic treatment even when the dog is perfectly healthy. That’s a problem not just for that individual dog, but for a much bigger issue: antibiotic resistance.
How the Study Was Conducted
Researchers conducted a cross-sectional survey — meaning they captured a snapshot in time — of breeders and veterinarians across the country. A total of 426 breeders completed the survey, and 94 veterinarians provided demographic data.
The survey asked breeders about:
- Whether they used antibiotics around breeding
- Whether they ran vaginal cultures on their dogs
- What drove their decision to treat with antibiotics
The researchers also looked at which factors were most strongly connected to antibiotic use — and vaginal bacteriology (bacteria found on a culture test) came out on top.
What the Numbers Revealed
One in Three Breeders Used Antibiotics at Breeding Time
Thirty-two percent of breeders in the survey reported giving antibiotics around the time of breeding. That’s a significant proportion, especially given that many of these dogs may not have had any signs of infection.
Culture Results Were the Strongest Driver of Treatment
The finding that stood out most was this: when a vaginal culture showed bacteria, breeders were far more likely to give antibiotics. The association between culture results and antibiotic use was strong across the dataset.
This suggests that many breeders — and possibly the vets advising them — are treating bacterial findings as automatic signals to medicate, even without other clinical signs of illness. In other words, the test result itself may be driving treatment decisions more than the dog’s actual health picture.
Bacteria on a Test ≠ A Sick Dog
One of the most important takeaways from this research is that bacterial presence alone does not necessarily indicate disease. A dog can have bacteria in her vaginal tract and be completely healthy. The researchers made this point clearly: treatment decisions should be based on clinical signs of disease — things like discharge, fever, pain, or other symptoms — not just test results in isolation.
What This Means for Breeding Dogs and Antibiotic Resistance
Antibiotic resistance is one of the biggest concerns in modern medicine, for both humans and animals. Every time antibiotics are used when they aren’t truly needed, bacteria have a chance to adapt and become harder to kill. Over time, this can make infections much more difficult to treat — and the same bacteria that evolved resistance in dogs can sometimes pose risks to people too.
For breeders, the takeaway is straightforward: don’t assume a positive vaginal culture means your dog needs antibiotics. Ask your vet whether the dog has actual clinical signs of infection — not just whether the lab found bacteria. A good vet will weigh the culture results alongside the dog’s overall health before recommending treatment.
When You Should Talk to Your Vet About Antibiotics
Not every finding on a vaginal culture warrants antibiotics — but some do. Here’s when to have a real conversation with your veterinarian:
- Your dog has symptoms alongside the culture result: unusual discharge, fever, lethargy, pain, or changes in urination
- Your vet found a specific type of bacteria known to cause reproductive infections in dogs
- Your dog has a history of reproductive problems that may make bacteria more clinically relevant
- Your vet recommends antibiotics and explains the clinical reasoning — not just “the culture showed bacteria”
If you’re ever unsure, it’s okay to ask: “Does my dog actually have signs of infection, or is this just bacteria on a test?” A thoughtful vet will welcome that question.
Study Limitations
This study used self-reported survey data from breeders, which means the numbers depend on what breeders remembered and chose to share — a source of potential bias. The study couldn’t directly verify every treatment decision or review each dog’s full clinical record. It also didn’t capture every factor that might influence antibiotic decisions, such as a breeder’s previous bad experiences with reproductive infections. Larger, more detailed studies would help confirm these patterns and better separate appropriate from unnecessary antibiotic use.
The Bottom Line
A survey of 426 dog breeders found that nearly a third reported using antibiotics around breeding — and the strongest predictor was a vaginal culture showing bacteria. But bacteria in a healthy dog don’t automatically mean illness. Experts say antibiotic use in breeding dogs should be guided by real clinical signs, not culture results alone.
If you breed dogs, this research is a reminder to work closely with your vet and ask the right questions before starting any antibiotic course. Protecting your dog’s health today — and the effectiveness of antibiotics for every dog tomorrow — depends on using these medications only when they’re truly needed.
This article summarizes peer-reviewed research for educational purposes. Always consult with your veterinarian for personalized advice about your pet’s health and behavior.