Kerri-Rae Millar was going about her Tuesday morning on June 10, 2025, when she received a call from a dairy client. He was asking for her opinion as his herd veterinarian on a pressing situation: A neighbour he shares a cattle trailer with had a positive test for bovine tuberculosis (bTB). His pressing concern: “What do I do?”
Millar, a vet at Morden Veterinary Clinic in Morden, Manitoba, opened her presentation at the 2026 Western Canadian Dairy Seminar with this experience. She addressed this case of bTB found in southern Manitoba and lessons learned from it during her speech.
Canada is considered bTB-free, thanks to mandatory testing and eradication implemented since 1923. However, Mycobacterium bovis, the bacteria that causes bTB, is still around at very low levels. bTB has been found very rarely and in very sporadic cases in cattle in Canada. bTB is also present in a few geographically localized wildlife populations – white-tailed deer in British Columbia and the bison in Wood Buffalo National Park. It is primarily spread by extended close contact between infected animals, feed, water and nasal secretions. It can also be spread in milk, semen, vaginal discharge and urine.
The case Millar addressed was found in a 7-year-old Holstein, culled for low production from a 100-cow herd. She showed no other symptoms of bTB – weight loss, decreased appetite, fever or cough. The index case was slaughtered at a federal facility in April 2025. At slaughter, lesions were found in multiple locations in the carcass and several lesions ”characteristic to bTB” were found in the lymph nodes. Tissues were sent to the lab for polymerase chain reaction (PCR) testing, and results showed a negative result. However, standard procedure requires tissue to also be cultured. bTB is a slow-growing organism, often taking eight to 14 weeks to grow in a culture. After growing in a Petri dish for two months, the case was confirmed a positive bTB. On June 9, 2025, the owner of the infected cow was notified by Canadian Food Inspection Agency (CFIA).
CFIA’s current bTB eradication program requires the entire herd and premises to go under quarantine after a positive test. The herd is tested and then humanely destroyed. The premises are cleaned and disinfected. An investigation is held; livestock and wildlife within proximity are tested. Once the herd is repopulated, the herd is tested again to ensure bTB is no longer present.
After the dairy producer was notified, it was important to assemble a team for the next steps of the program. This included the provincial milk marketing board and the chief veterinary and public health offices. Meetings were coordinated and investigations into protocols were held. DairyTrace allowed for a much easier process and provided the materials needed to CFIA before they even asked.
CFIA has several ongoing beef investigations, but this was the first dairy case they had worked on.
“I’m not sure how many different meetings it took before everyone finally realized that robots milk cows 24 hours per day,” Millar said. “We did make a lot of progress – I think they [CFIA] understand dairy farms much better.”
After initial meetings were held and a plan was in place, quarantine began. Nothing came to or left the farm.
CFIA led investigation testing, requiring all animals to have a caudal fold test (CFT) bTB test prior to slaughter. Tests were read 72 hours after administration. Animals that read negative were sent to a slaughter facility. Animals that reacted to the test were required to undergo an enhanced postmortem examination after slaughter at a separate facility.
“We want this to occur as quickly as possible,” Millar said. “This is your livelihood. I know everyone in this audience understands that and knows the severity of that. It’s also a very traumatic experience.”
Millar suggested that depopulation should occur off-site if possible.
“The less the producer has to see, the better,” she said. “This is hard on everyone, even those doing the postmortem examinations. As a veterinarian, we’re used to doing all those things, but it’s completely different when it’s a herd of relatively healthy animals. It’s heartbreaking.”
Millar noted that having a supportive community is very helpful during such a stressful situation. In this case, veterinarians, neighbours and other dairy producers stepped up to help.
The federal Health of Animals Act allows producers to be compensated for animals destroyed to control disease. As of June 2025, maximum compensation amounts for cattle are $10,000 for non-registered animals and $16,500 for registered animals. It is up to the producer to prove the value of each animal in the herd.
Cleaning and disinfecting is up to the producer – he or she sets the parameters for this part of the plan and CFIA signs off on it. In the Manitoba case, the barnyard was split into different locations to be cleaned and disinfected in stages. Once an area is cleaned and disinfected, it must be empty for at least 45 days before restocking – dependent upon temperature and precipitation.
“They had the cow barn cleaned and disinfected within a week, and the clock on those 45 days started the following week,” Millar said. “Not surprising to this room – dairy farmers get stuff done. Everyone was very prompt, and we just wanted things to get back to normal – as normal as it can be. In terms of disease investigations, this one moved at rocket speed.”
A quick timeline: June 9, the positive bTB case was identified. June 30, the entire herd had been depopulated. July 9, the lactating barn had been cleaned and disinfected. By late August, the producer was filling his barn again.
Restocking the herd is not an easy task. Not only were a certain number of lactating cows needed, cattle in every stage of life – from bottle calves to dry cows – must be replaced. Through local acquisition, the producer slowly began rebuilding his herd.
Neighbouring herds were tested – including five herds from which the producer had purchased animals from in recent years – and subsequent investigations were held. No other animals tested have been positive for bTB.
“So how did she get TB?” Millar said. “We don’t know. She’s a home-raised cow, lived on the farm her entire life. It didn’t come from one of the other producers. The really neat thing they can do with bacteria now is the ability to identify genetic fingerprints. This particular strain didn’t show any similarities to other cases in Canada – in beef herds or wildlife.”
As for Millar's client – who shared the cattle trailer with the index herd – risk of infection was low as cattle did not intermingle on farm or on the trailer. As timelines unfolded, there was ample time between hauling the infected cow and the client's use of the trailer, reducing risk further. Ultimately, CFIA would contact anyone whose cows might have been in contact with the index case.
Millar closed out her presentation with a few parting thoughts.
“Cases are sporadic. It is expected to have more in Canada. I hope nobody has to deal with it, but you just never know. Most diseases are bought and paid for, but some diseases are just bad luck. Practice good farm biosecurity. Keep your records up to date.
“What do you do if you’re in one of these situations? Give yourself some time. Ask for help, phone your herd vet, milk marketing board, neighbour. Dairy is a small community but a great community. There are a lot of people working for you in the background – locally, provincially and federally. We all learned a lot from this situation.”
