The last thing Jim Stangle, DVM, expected to have to deal with in his Milesville, S.D., practice was an unexpected outbreak of trichomoniasis in his clients’ herds. In 2005, 52 trich-positive herds were discovered in western South Dakota where the disease was rare. “The first year you have trich, you may have a minimal impact on pregnancy rates,” Stangle says. “The few infected cows would abort toward the end of the season, then all of your bulls would get infected. When you start your next breeding season with infected bulls, you get a wreck. I saw that in more than one case.”
Stangle credits the drought for the introduction of trich into the state. “Cattle moved around a lot during the drought, and we had a lot of potential for exposure from several different sources,” he explains. Cows and bulls came from other states, and shared grazing in the Black Hills probably contributed. “You may know where your cows have been, but you don’t know where your neighbor’s cows have been,” Stangle says.
Calving losses and low reproductive rates
Caused by the Tritrichomonas foetus protozoan and spread between bulls and cows, trichomoniasis has been described as a silent calf thief. It causes an inflammatory response in the uterus approximately 42 to 56 days after insemination and can cause abortions six to eight weeks after conception. Some of the effects are so insidious that producers do not realize they have trich, especially in herds with year-round calving seasons. “Producers may only lose a few calves because trich is at a low endemic level, and there may be some herd immunity due to the constant exposure,” says Soren Rodning, DVM, Auburn University Extension veterinarian.
Carlos Bonnot, DVM, Wharton, Texas, sees a lot of summer versus spring calves. “Producers ask why their cows are getting bred later and later in the breeding season and that raises a red flag,” he notes. “If trich is introduced into a naïve herd, we’ll see about 30% pregnancy loss. Our calving intervals get spread out to 16 or 17 months.”
A thousand miles to the east in Lake Placid, Fla., John Yelvington, DVM, says initially you’ll see a decline in weaning weights, even with good preg check results. “As you get more infected bulls, that hurts your reproductive rate,” he says. “Some of our older cow herds have a steady decline in weaning weights.” Increasing the amount of time the bulls spend with the cows only causes a further decline.
Manage the cows
If cows that should be bred and settled down continue to cycle when the breeding season is over, that can indicate a problem. “We see it surface with a lot of riding, a lot of cycling later in the breeding stage,” says Don Crum, DVM, Alturas, Calif. “At the tail end of the breeding season, people have
discovered they have 30-35% of their cows open, and you’ll see a lot of big, firm, scarred reproductive tracts. In one herd, I checked 170 cows and had 70 open. You have to identify open cows.”
Extended breeding seasons can allow trich to proliferate. South Dakota has shorter seasons -- rarely over 90 days and most in the 60- to 70-day range. “Last year, we went from 52 positive herds to two this year,” Stangle says. “Maybe it’s because our breeding seasons are not extended and infected cows are not having the chance to re-infect bulls. We’re preg testing and getting rid of opens.”
It takes only one animal to screw up a bio-surveillance program. One of Stangle’s herds went from 3% to 47% open in one year. The owner sold all his bulls and used all yearling bulls the next year and then had 7% open. “He left back one open milk cow,” cites Stangle. “He tried to get her bred at the start of the next breeding season and he was back to 30% open. One cow was all it took.” Selling your open cows is a must from a trich biosecurity standpoint, not to mention an economic standpoint, Rodning adds.
Manage the bulls
In northern California range herds, many bulls are left out for six months. “They get early abortions,” Crum says. “They figure the cows will breed back in five to six months, so they’ve gone from spring calvers to fall calvers. They have cows cycling and all the bulls get infected later in the summer, which has caused some damage to bull herds.”
In Yelvington’s large Florida herds, culling infected bulls has decreased the trich reservoir. One operation had a six-month breeding season and divided the cows into “early bred” or “late bred.” “When we were dealing with trich, often that late herd would be in excess of 1,500 cows,” he explains. “After getting rid of all positive bulls, we had fewer than 150 cows in that late-bred group, and most were bred in the first 90 days.”
Bull management has changed, Stangle says. “In the old days, if you found your neighbor’s bull with your cows, you took him home. Now, you put him in a corral, notify your neighbor, find out if he’s been tested, and hold him there until he’s tested.”
Stangle says one grazing association agreed that all bulls required two negative tests to graze in the association. “If a bull crawled out once, he was forgiven. If he did it again, that was the end for him. If that bull gets out, you have to identify him. I’ve been toying with the idea of making my own trich tag so they’ll know a bull has been tested.”
If cows are infected, no amount of virgin bulls will solve the problem. “In a herd that had 28% open cows, we had 28 out of 50 bulls infected,” says Crum. “All of the bulls got infected within a short time. You go out and buy young bulls that have had no vaccine, no immunity, and you turn them in. You’re going to infect those young bulls like crazy. We find 70-80% of our infected bulls are two- and three-year-olds.”
Replacing culture-positive bulls with virgin bulls is ideal, but if virgin bulls are not an option, the next best thing would probably be to replace with younger trich-negative bulls. “The chance of a younger bull being a chronic carrier of trich may be somewhat less,” Rodning says, “but even two-year-old bulls can be chronically infected with trich. A long-standing false dogma is that young bulls don’t become chronic carriers. While it may be true they are not as likely to become chronic carriers, any bull that has ever bred a cow should be tested for trich prior to purchase.”
Crum believes that older bulls will have a lower incidence of trich because they build immunity, even though the cows will still be infected. “We’re always told to cull old bulls and get young bulls, but I don’t think that may be right. If you buy non-immune young bulls without any trich that are not vaccinated, they’ll get infected. They’re more likely to crawl through a fence to breed the neighbor’s cows and bring it home.”
Crum doesn’t like to see 7-year-old bulls in a herd either, but he rarely finds a positive among them. “That’s why we decided if they were going to immunize themselves with age, let’s start vaccinating the bull herd. We’ll give them any immunity we can possibly give them, and that’s really cut our bull-loss percentage down.”
Another thing to think about are leased bulls. “Historically, in Nevada, trich went back to somebody who leased bulls,” says Bill Kvasnicka, DVM, retired University of Nevada Extension veterinarian. “We also have common grazing with as many as five producers on one allotment, bad fences and buying bulls that haven’t been tested.”
Testing for trich
Stangle’s plan is simple: test bulls, sell all positive bulls, preg test cows in the fall, and sell all the opens -- without question. Be aggressive on testing, whether or not you think you have the disease. “In the first herd, we picked it up in good cows that shouldn’t have been 25% open. We cultured six positive pyometras. Then we started testing bulls.”
The gold standard for trich testing is the InPouch™ TF test from BioMed Diagnostics, Inc. “If you have a microscope, you can show the rancher his problem and that’s very convincing,” Kvasnicka says says. “Sometimes you can see clinical signs, but you don’t find any positive bulls. But if you go to the slaughterhouse and recover those reproductive tracts, you can get a diagnosis.”
The literature recommends three tests on bulls for specificity, but Kvasnicka surmises that two tests of each bull is probably practical. “We can probably get 85% on that first test and maybe another 8-9% on the second test,” adds Yelvington. We have not found a third test to be rewarding.” He likes to test one time through the bulls, and then test a second time during breeding soundness exams. “If we do have a problem with identifying it, we’ll do a PCR, but once you have looked at it quite a few times, its movement and its size are very recognizable.”
Kvasnicka recommends testing a couple of weeks after the breeding season and keeping the bulls in a clean grass pasture. “Utah, for example, requires a test just before the breeding season, but if you have positive bulls, why not find out in the fall?”
Rodning notes that it’s important to give the bull at least a couple of weeks of sexual rest and let the organism multiply on his penis/prepuce to increase the odds of sampling trich.
When possible, sending in an aborted calf for testing can be rewarding. Bonnot puts the aborted fetus in a bag and ices it down before he sends it in. “If we get the cow up, we will take a blood sample to screen for Neospora and other reproductive diseases and submit any afterbirth, if present. I’ll
aspirate some fluid out of her uterus at the time of the abortion, and do a direct exam.”
Crum says in California, they had a 4½-month-old fetus diagnosed with trich in the stomach. “I recently heard that 7-month and 8-month aborted fetuses have been picked up at some of the dairies,” he says. “It was new to me to hear of these late-term fetal abortions from trich.”
How to test
Each of the veterinarians has had varied experience getting the best test results. To collect the best sample and minimize contamination, trim the preputial hairs and wipe around the preputial orifice with a clean paper towel, Rodning says. This can prevent contamination from yeast, bacteria and other fecal contaminants, possibly even some fecal protozoans. “Too much contamination and the InPouch is more likely to swell because of gas production,” he says. “You have to let the gas out to be able to read it. Also, the presence of fecal trichomonads can confound your diagnosis, but a PCR-based assay can determine if you really have T. foetus.”
If the first sample is muddy, Stangle flushes the sheath with saline. Urine contamination is another concern he has, but he doesn’t know if urine contamination affects the trich test. “With a bull urinating a lot, I usually get a little more vigorous with my pipette and work it without the suction until he stops urinating, and then I take the sample to get less urine contamination.”
Rodning takes a 21-inch pipette with a 20-ml syringe and puts the pipette into the preputial fornix, scraping along the prepuce and the shaft of the penis while aspirating with the 20-ml syringe. Stangle believes that some of the trich is in the crypts of the glans and that’s where you have the most exposure when you’re semen testing. “I don’t try to ram up into the fornix as hard as I can, but you get a feel for how rough it is going past the glans,” he says. “That’s what I want to feel when I’m collecting those bulls.”
“It’s difficult to read samples if you have too much blood,” Rodning explains. “If I get a light pink, I consider that to be a good sample.”
Bonnot has changed his technique to avoid problems, as well. “We were instructed to scrape that prepuce way up in the fornix just as hard as we could. I’ve sent them in bloody, and I’ve sent them in muddy. We changed labs, and they advised us to back off being so aggressive and send a pouch solution of light pink.” To get a sample with only a small amount of blood, Bonnot takes a thread-maker and puts grooves on the end of an AI pipette. “If you thread that pipette, it speeds up the process.” Since changing techniques, the number of positive bulls he’s picked up has increased.
Crum has been trich testing for 25 years and likes to culture before semen testing to avoid a lot of sperm in the sample, then he reads samples the next day. “We usually take a Styrofoam box and put a jug of hot water in it. When we come in from the field, we’ll put them in the incubator.”
The veterinarians also advise against overloading the pouch and letting air into the bottom of the pouch. If air gets in, try to force it back out. “Trich is microaerophilic,” Stangle explains. “It doesn’t like a lot of oxygen, so I try to keep that out of there.”
It’s important to remember that the InPouches expire, Rodning warns, so check the expiration date. “If the InPouch is coffee-colored, it is definitely no longer good.”
It’s possible that the veterinarian can spread trich while semen testing. Stangle uses a four-by-four piece of gauze to grasp the penis once it is extended. “I used to use the same gauze on seven or eight bulls until it got dirty. Now it’s a new gauze for every one. If I did have a trich-infected herd, I wouldn’t want to take the chance of spreading it from bull to bull.” Stangle also uses a new pipette on every bull, but uses the same syringe unless it gets contaminated, as do Crum and Yelvington.
Vaccination combined with testing and culling help control trich. All of Stangle’s herds cleaned it up without vaccination, but he stresses that if a client is going into a high-risk area, he should vaccinate. “You also have to emphasize that vaccination does not mean you can stop testing bulls and cows. You still have to do both.”
Vaccination timing is a key factor to its success. “The data I get from the field is if the vaccine program is to be successful, it needs to be given before the breeding season,” Kvasnicka suggests. “We have had ranchers who said they couldn’t do it -- and they say the same thing with BVDV and IBR. The majority who are successful with their vaccination program have changed
to giving the vaccine before the breeding season.”
Yelvington agrees. “The two biggest things in my mind are testing, then culling positive bulls, and it’s essential to vaccinate that cow herd as close as possible to the label instructions. Where we’ve done that, they’ve cleaned up fairly fast. Where people were not able to do that, clearing up trich problems took twice the time.”
There will always be clients who cannot or will not vaccinate at the onset of the breeding season. So when is the best time in that situation? “In our practice area, producers pen and work their cattle twice yearly, spring and fall,” Bonnot says. “Bulls are turned out between these two workings.” Bonnot recommends the October-November timeframe, sometimes three or four months prior to bull turnout, rather than in April-May after the bulls have been out 60 or so days.
As far as seedstock producers, Crum recommends they get at least a dose of vaccine into bulls before they sell them; then when they bring them home and brand them, give them a second dose. “It’s not going to solve everything, but it will help. We vaccinate the bulls twice a year if we can get the producer to do it.”
The veterinarian plays a key role in trichomoniasis prevention and management -- especially in areas where the disease isn’t well-known. “When trich is new to an area and the ranchers are scared, some start pointing fingers and blaming the first person who has it diagnosed on his place,” Stangle says from experience. “Some will even threaten lawsuits. In order for a lawsuit to be successful, the accuser would have to prove that his whole herd, cows and bulls, were negative prior to exposure. And that’s a no-win situation. Veterinarians should be at the forefront of education.”
Crum suggests a more public means of communication. “If you get a new disease in the area, go right to the newspaper and be the expert. Meetings are helpful for education, and I’ve used a handout for the last 15 years to educate about trich. That’s something clients can read at home and get educated.”
Kvasnicka suggests framing the education in terms of herd -- not individual -- diagnosis. “If you get one diagnosis, look at it as a herd problem. Don’t worry about how many bulls are infected. Manage the whole herd and not just the bulls.”
It’s also important to temper the message with the risk. Kvasnicka says we know what the risk factors are, and when the veterinarian gets on the ranch four times a year he/she should outline all the risk factors. “If the risk factors aren’t there, you can think about stopping vaccination. But, you have to follow it up with a biosecurity program determined by the risk factors such as neighbors with fences in common, where you buy your bulls and following basic biosecurity rules.”
Helping clients maintain basic reproductive records, if they don’t already, is another tool.
“Going the extra mile could include birth weights, bull calf/heifer calf, calving problems, etc., but simply recording calving dates and keeping track of calving intervals would be a great start and possibly help identify trich,” Rodning suggests.
Rodning’s mission is to help producers prevent spread of disease.
“Producer biosecurity -- for trich or anything else -- is extremely important. I haven’t found trich in Alabama myself, but there have been cases of it over the last 20 years. We don’t have a high level of trich, and I want to avoid getting a high level. Preventive medicine is the key to avoiding disasters, and biosecurity is a big part of that.”
This information is from a roundtable sponsored by Fort Dodge Animal Health.
The economic impact of trichomoniasis can be significant due to reduced calf crop from early embryonic loss or abortion, reduced weaning weight due to delayed conception, and culling and replacement of infected cattle.
Jim Stangle, DVM, has seen 50% calf crops due to trich, and says at $800 per calf, even a 20% loss in calves is significant. Don Crum, DVM, adds that good cows that are worth $1,000 to $1,200 will have a $500 per cow loss for every one that’s open because of trich. “We’re probably also losing $1,000 to $1,500 on black bulls,” he says.
One of the most economically devastating effects of trich is a prolonged calving season with the majority of calves being born at the end of the season. The result is a wide range in weaning weights, which also makes it difficult from a marketing standpoint when trying to put together a uniform group of calves. “Perhaps the cows get pregnant in the early part of the breeding season, and then they abort and get bred again at the tail end of it,” says Soren Rodning, DVM. “The cow may have a calf, but with poor records the producer doesn’t know if that calf was born 18 months from the last one or 12 months from the last one.”
The producer realizes the economic importance when he weans his calves and has to load 115 calves on the trailer instead of 95 to make 48,000 pounds, adds John Yelvington, DVM. “The decline in that weaning weight sinks home.”
COULD TRICH BE A LEGISLATED DISEASE?
Because of the speed at which trich infected herds in 2005, South Dakota passed some aggressive trich laws, such as all killer bulls are supposed to go to kill. “I don’t know how you police that,” says Jim Stangle, DVM. “But all bulls cannot go back to the country and neither can open cows in South
Dakota sale barns.” Stangle says sale barns had the potential to be some of the biggest perpetrators. “They’d buy open cows in the spring and turn them out with bulls also bought at the sale barn. We’ve passed some pretty aggressive laws, and at least conscience will keep most of that out of the system.”
In California, trich-positive cattle are supposed to be silver-tagged. “When they go to the sale yard, they’re supposed to sell them as slaughter only,” says Don Crum, DVM. “We did have an incident where positive bulls were re-sold. We really need to have a back tab or something on those saying slaughter only. We don’t always get the silver tags in on time.”
Bill Kvasnicka, DVM, notes that in California, Oregon and Utah if a ranch is diagnosed positive, the neighbors are at least made aware of the problem. Some of the grazing associations are also changing requirements.
In the case of seedstock producers, Carlos Bonnot, DVM, says there are situations when a bull is purchased from a reputable breeder but then returned in two to three months for various reasons. It is possible that this returned bull will replace another bull or be resold. “The seedstock producers are not requiring a returned bull to be tested for trich. When they take a bull back from someone who wasn’t happy and they replace him with another bull that somebody else wasn’t happy with, you don’t know where that bull has been or what he’s been exposed to.”