Trichomoniasis: An age-old disease may cause
new problems in your clients’ cow-calf herds

You have a client whose cow herd comes up 30% open at pregnancy-check time. The year before, his spring calving schedule became a spring-and-summer schedule due to a number of late breeders. Their calf crop was uneven, some cows thought to be pregnant never calved, and weaning weights suffered.

The cause of this scenario could be a number of different issues, but a highly likely culprit is trichomoniasis. While certainly not a new disease, trichomoniasis is extremely common in some parts of the United States, and, unfortunately, becoming more so in others.

Fort Dodge Animal Health recently sponsored a roundtable discussion on the disease, featuring the opinions and insights of leading cow-calf practitioners and university researchers from across the country. Here’s what these experts had to say.

Disease etiology

Even young bulls are susceptible to trichomoniasis. Essentially, any bull performing natural service is at risk of contracting the disease.

Trichomoniasis is a venereal disease in cattle caused by the protozoan Tritrichomonas foetus. While bulls are the primary reservoir and vector of the organism, “we’re finding that the cow also is a reservoir of infection,” says Bill Kvasnicka, DVM, retired Extension veterinarian from
the University of Nevada.

The organism lives in the crypts on the mucosal surface of the penis and prepuce of the bull. Trials have shown that it is not cultured from the epididymis or the testicles, and it does not affect semen
quality or sexual desire of the bull.

Cows acquire the protozoa upon insemination by an infected bull. The organism infects the lining of the uterus, vagina, oviducts and cervix, making it possible for cows to transmit the disease to other bulls if inseminated by more than one animal. “I had a client who had one heifer that he couldn’t control,” relates Jim Stangle, DVM, of Milesville, South Dakota. “She visited the neighbor’s bull that had trichomoniasis. The rancher brought her home and then she infected all of his bulls. The next year he had a 50% calf crop. That’s how bad it can be.”

Trichomoniasis causes an inflammatory response in the uterus of the cow approximately 42 to 56 days after insemination by an infected bull. It is believed that this timeframe accounts for the high incidence of abortions starting at six to eight weeks after conception in newly infected animals. The infection process is not a random event, as 80 to 90% of cows bred by an infected bull will acquire the disease.

Infected cows display no clinical symptoms of trichomoniasis, but Alturas, Calif. practitioner Donald Crum, DVM, says the disease manifests itself in cows in a number of ways, including:

• A disproportionate number of open cows at pregnancy check
• Late abortions
• Extended calving season
• Mild to severe pyometra in some, but not all, infected cows
• Large, firm reproductive tracts in some cases, as the result of metritis and
  scarring of the uterus.

The initial impact of the disease on a cow herd may be subtle. Soren Rodning, DVM, Auburn University Extension Veterinarian, says herds with year-round calving seasons may be less likely to notice the early signs of trichomoniasis. This is especially true because an initially infected cow can abort one fetus, conceive four to five months later, and carry that calf to term. “Without good records, producers don’t know if a cow’s calf was born 12 months or 18 months from her last one,” says Rodning.

If trichomoniasis persists in a cow herd for a year or more, the consequences are more grave. Although most cows will clear of the infection within about 95 to 160 days, the after-effects remain. “We’ll see scarring and adhesions in the reproductive tract, and those cows won’t breed back the next year,” says Crum.

He adds that bulls also will display no visible signs of the disease. While some experts say that the majority of bulls chronically infected with trichomoniasis are four years old and older, others believe that younger bulls are just as susceptible to acquiring the infection. “We actually tend to find more infections in young bulls, which I believe is due to lower immunity and more vigorous breeding desire,” says Crum. The upshot: no bull that is performing natural service is immune from the possibility of acquiring trichomoniasis.

Regional realities

Trichomoniasis does not have equal presence in all parts of the United States. In fact, some practitioners and beef producers have never seen it. Conversely, in regions like the western grazing states, it is a fairly endemic problem that has been present for years, and requires constant, vigilant attention.

And then there are the unfortunate regions that used to be trichomoniasis-free, but are now all too familiar with it. “When it moved into my practice area a couple of years ago, no one knew anything about it,” shares Stangle. “The drought further west brought it to us, because cow herds and bulls were sold to ranchers here, or temporarily brought into shared grazing situations here. Cattle movement and biosecurity are huge factors with this disease. We learned the hard way how easily it can slip through the back door, and how quickly it can engulf a herd.”

Distribution of cases in a herd infected with trichomoniasis A rancher can have a 90% calving rate and still be living with trichomoniasis. Source: Berry & Norman 1990.

Rodning notes that herd size often influences the presence of trichomoniasis, with smaller herds less likely to be infested. “In Alabama, 85% of our producers have fewer than 50 cows, and as a result, we don't have much trichomoniasis. However, some producers do lease or share bulls, putting them at greater risk for trichomoniasis. Bad fences are another risk factor, along with not testing bulls for trichomoniasis prior to purchasing,” he says.

Still further south, John Yelvington, DVM, who practices in Lake Placid, Fla., says large herds of 500 or more cows tend to have higher infestations of the disease. “We have some large, older cow herds that definitely have shown declining weaning weights over the years,” he notes. “A lot of times they’ll try to compensate by increasing the amount of time bulls spend with cows, but all that does is make the problem worse.”

Shared grazing lands and open-range grazing have perpetuated the incidence of trichomoniasis in the West for many years, according to Crum and Kvasnicka. “We’ve had people culture bulls for trichomoniasis for 15 years and they’ve never had a positive, but they know their neighbors have it,” says Crum. “Most of our bigger ranchers vaccinate the whole cow herd because it just keeps showing up every three or four years.”

Economic impact

While their experiences with the disease vary, all of the practitioners who participated in the roundtable discussion agree that trichomoniasis can be economically devastating to a cow-calf producer.

“In the first year of infection, it is possible for a producer to perceive he has a 90% calving rate,” says Carlos Bonnot, DVM, who practices in the Gulf Coast region around Wharton, Texas. “But one must remember that that could be a 90% calving rate in 14 to 18 months. It’s a costly disease from the get-go, but it may take a while and some education to convince clients of that fact.”

Crum calculates that if a herd of 500 cows has 40% non-pregnant females (200 open cows) due to trichomoniasis, plus 10 infected bulls that must be slaughtered, the loss to the ranch would be $400 per lost pregnancy,plus $1,000 perculled bull. Total loss: $90,000. Herds often lose a lot of their genetic potential due to trichomoniasis, because heifers, with smaller reproductive tracts, tend to be more susceptible. Add to this the additional cost of reduced weaning weights, longer calving intervals and the cost of replacements,and it’s easy to see why trichomoniasis has put many ranches out of business.

“It’s a little harder to get producers concerned about trichomoniasis, because it does not receive nearly as much publicity as BVDV, IBR or leptospirosis,” says Rodning. “Also, trichomoniasis is not likely to cause a late-term abortion storm, and calves that are born do not have congenital abnormalities like you might see with BVDV. Adult animals also don’t die from it, so the onset of trichomoniasis can be very insidious.” He adds that diagnosis can be confounded by the fact that common symptoms may cause confusion between trichomoniasis and BVDV, leptospirosis and other diseases or circumstances.

Cleaning house

The roundtable participants concurred on the comprehensive approach that clients should take to cleanup a trichomoniasis outbreak in a cow-calf herd, and prevent it from re-entering the operation:

• Test all bulls approximately two to three weeks after the breeding season, and cull those that test positive.
• Cull all cows found open at pregnancy checking, as well as those that may have had late abortions and do not calve with the rest of the herd.
• Isolate and test incoming bulls to safeguard against buying the problem.
• Use A.I. as an alternative to natural service.
• Do not lease or share bulls unless an agreed upon trichomoniasis testing and surveillance program is in place.
• Do not sell bulls onto the open market that are known to be trichomoniasis-infected.
• Sterilize CIDR applicators between animals, and do not reuse CIDRs when synchronizing cows and heifers.
• Vaccinate heifers and cows on an ongoing schedule, if the disease is at all present in the region.
• Record calving dates and weaning weights, at a minimum, to promote early detection.

The last piece of advice may sound too obvious to even include, but, unfortunately, lack of record keeping is a primary contributor to the undetected spread of trichomoniasis. “If everyone kept records, we wouldn’t need to have this discussion at all,” states Bonnot.

Vaccinate to keep
trichomoniasis in check

Vaccinating against trichomoniasis on an ongoing basis was viewed by most of the roundtable participants as the only way to fully ensure that a herd is protected from the disease. The TrichGuard® Trichomonas Foetus Vaccine from Fort Dodge Animal Health is the first and only vaccine available to vaccinate cattle against Tritrichomonas foetus. It is a whole-cell, killed protozoa vaccine. The recommended procedure and schedule for vaccinating female cattle with TrichGuard are:

• Inject one, 2-mL dose. Repeat in two to four weeks, ideally preceding breeding season
  by four weeks.
• Revaccinate annually.
• Do not administer vaccine within 60 days of slaughter.

The vaccine also is available as TrichGuard V5LTM V5L, which is a combined formulation with a leptospirosis vaccine and should be administered at 5 mL per dose on the same schedule. Both vaccines are safe for use in pregnant animals. A study published in the American Journal of Veterinary Research¹ in 2004 described a simulation model to evaluate various trichomoniasis risk factors, along with vaccine efficacy. The researchers concluded that, in all simulations, vaccination resulted in significantly higher calving incidence than nonvaccination.

¹ American Journal of Veterinary Research 65: 770-775.
TrichGuard and TrichGuard V5L are registered trademarks of Fort Dodge Laboratories, Inc.

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