Health updates: State Vet explains brucellosis, trich statusWritten by Christy Martinez
Logan was present to give an update on animal health, which included brucellosis and trichomonaisis in cattle, as well as EHV-1 and vesicular stomatitis in horses, at the early May meeting of the Joint Ag Committee in Lander.
Of the two herds under quarantine for brucellosis in Park County, Logan said he expects the cattle herd to be off quarantine soon since its completion of two negative whole-herd tests. The second case is a domestic bison herd, and he said it has yet to accomplish a negative whole-herd test.
“It’s likely to remain under quarantine for quite a while,” said Logan. “We’ve been doing the test and removing any suspects or reactors to slaughter or to terminal feeding. We have a cooperative owner, but a complicated situation with bison because we can’t work them on a whim like we sometimes work cattle.”
Logan said the herd is unlikely to affect Wyoming’s brucellosis-free status because APHIS is still operating under the interim rule published in late 2011.
“Had we been working under the old rule, Wyoming, Montana and Idaho would have all lost their brucellosis-free status, and everybody who sells cattle in those three states would be testing on change of ownership,” he said. “We’re fortunate we’re working under the interim rule, and as long as we continue to appropriately deal with cases, I don’t think this brucellosis testing will put our status in jeopardy.”
Suspect under testing
Logan said the stabilized suspect from the DSA is undergoing a weekly test on both it and its calf.
“The cow was found on a change of ownership test, and we have it at the Wyoming State Vet Lab for continued diagnostic testing and some research,” noted Logan. “On her weekly tests, it looks like the test values are decreasing.”
Logan said there was a similar animal a year ago, and eventually that animal was determined to be negative, although she didn’t go back into the breeding herd.
“At this point we haven’t quarantined the herd in relation to this one, and I don’t expect we will have to, but I do want to get some answers from this animal and her calf,” said Logan. “There are some big implications if she was to be a positive.”
Trich cases lead to more testing
There have been seven new cases of trichomoniasis, or trich, in Wyoming since December 2011.
“We’ve had seven different ranches with numerous bulls,” explained Logan, adding that they were in Sweetwater, Lincoln and Fremont counties.
“As a result of the numerous cases in Lincoln, Uinta and Sweetwater counties and several meetings, those producers requested the Wyoming Livestock Board require more stringent testing in their areas,” said Logan of the board order that was put in place on April 24 and includes Lincoln County except for the area northeast of Fontanelle Creek Road, all of Uinta County and all of Sweetwater County south of Interstate 80 to the state line.
“I hope this testing will help us to get the infection found in these herds,” said Logan. “This board order pertains not only to those animals that run in common on common grazing, but every bull turned out for breeding purposes, even on private property with no commingling. I haven’t heard any complaints from any producers, and I hope we can get the areas found where the infection is so we can get it cleaned up.”
Logan said the main enforcement will lie, in large part, with the industry itself.
“Producers will have to report to us if they were aware of violations. I hope everybody complies, but I expect we won’t have full compliance and I hope we will have producers call and tell us,” he said. “Our ability to enforce this aggressively will lie with one or two enforcement officers in that area and the brand inspection force in the field. Our field vet is in Lincoln County, and one of his assignments will be to keep an eye out, but it will be up to the industry to make reports of violations when they’re aware of them.”
Logan said the main reason the board order and stringent testing were confined to the three counties is because the WLSB has found index cases and expansion of the infection when they did exposed herd testing.
“I’m not against having more stringent testing on other areas of the state, but the industry needs to look at this,” he said. “It will be an expense to the industry, and having the disease is a huge expense to the industry – some people talk about hundreds of thousands of dollars of expense in individual herds. Statewide, the industry and the board need to look at this and perhaps do some cost analyses, risk analyses and some cost/benefit studies to determine if testing will be the thing, or a better job on educating about management.”
Trich: the solution is management
‘Manage’ is the key word. There is not a good vaccine, and both bulls and cows can carry the disease,” said Wyoming State Veterinarian Jim Logan when explaining trich regulations to the Joint Ag Committee at their early May meeting in Lander.
“Less that one percent of females that become infected will harbor the disease for a lifetime and infect every bull that breeds them, but cows that become infected typically will spontaneously clean up, absent continued breeding exposure,” he said. “Usually it’s after two to four heat cycles, and if they’re not exposed to another infected bull they can breed and carry a calf.”
However, he said the immunity that’s developed by natural exposure or the vaccine is very short-lived, so cows can become infected every year, or more often in a year if they’re exposed again to an infected bull.
“With bulls, they’re lifelong carriers. We used to think young bulls sometimes might clean up, but the industry cannot count on that,” said Logan.
“Our rules require a producer with an infected bull to test their entire bull battery with three negative culture tests or one negative culture and one negative PCR, which is a genetic test for the organism, or two negative PCR tests,” said Logan. “Either that, or the entire bull battery is required to go direct to slaughter and be branded on the hip.”
To address the female side, Logan said part of the quarantine release for an infected herd in the Wyoming Livestock Board’s new rules does require female cattle to be preg tested and found to be at least 120 days pregnant, or verified that they have not had breeding exposure for a minimum of 120 days.
Logan strongly advises against buying used bulls or open cows from sale barns, and he says the real management difficulty lies in common grazing allotments.
“If everybody complies with the requirements but one person, that one person can impact a lot of people,” he said. “In a lot of areas, especially Uinta County, quite a few people don’t technically graze on common grazing, but they graze on very large, expansive and rough country and BLM allotments that are unfenced or poorly fenced. Some producers have been able to get by our rules, but ultimately their cattle end up commingling, and that’s where a lot of other herds become infected.”
State monitors equine health
Regarding EHV-1 in horses, Wyoming State Veterinarian Jim Logan says, “We do still have some cases being identified around the country, and California has seen some, but we haven’t seen any in Wyoming.”
In his report to the Joint Ag Committee in early May, Logan said that in late April he did get notification of EHV-1 abortion syndrome on one horse farm in the state.
“It’s the same virus, but a different manifestation of the disease, so we’ll continue to keep an eye out for this,” he noted.
Logan said there are also two cases in horses with the suspicion for vesicular stomatitis (VS).
“The first case was determined through thorough testing at the National Veterinary Services Lab to be nothing of importance. The one we’re investigating right now does not seem to be anything, but the samples are taken and are on their way to the lab,” said Logan, adding that he’s concerned about the possibility of the cases being something because on April 30 New Mexico found a positive VS on one premises in a couple horses.
“At this point in time, we have decided we don’t need to do anything additional regarding New Mexico animals, but we’re watching that closely,” he stated. “If it appears that infection is spreading I would put a restriction on New Mexico horses coming in with a health certificate much less than 30 days.”