I was recently involved in a disease investigation where the presenting complaint was infertility. This particular cow-calf herd had cows that were continuing to cycle despite several breeding attempts. It was a particularly well-managed herd with excellent nutritional management and a good vaccination program.
As part of our investigation, we took vaginal swabs from some of the problem cases and 100 percent tested positive for a bacteria called “Ureaplasma diversum.”
Ureaplasma diversum is in the same family as the mycoplasma family of bacteria and is a common inhabitant of the genital tract of cattle. It was first isolated in 1969 and was first thought to not cause any disease issues.
However, subsequent research in the1970s and 1980s suggested that Ureaplasma could be associated with failure of pregnancy at various times of gestation in cattle.
In cows, the bacteria have been associated with an inflammatory condition in the vaginal wall, which may cause reddening and the formation of granules on the vaginal wall. In some cases, there may be some vaginal discharge as well.
Several research studies have associated Ureaplasma infections with increased levels of embryonic death and return to estrus. In these cases, the bacteria is thought to have moved from the vaginal wall and infected the uterus of the cow. Late-term abortions and the birth of weak calves have also been associated with the infection of the uterus and in those cases, veterinary pathologists may be able to see lesions in the placenta and in the lungs of the fetus.
The main mode of transmission of the bacteria is through breeding. Bulls can carry the infection and pass it from cow to cow during breeding. As well, artificial insemination with infected semen can be responsible for transmission of the bacteria.
However, it is important to understand that Ureaplasma diversum can also be isolated from cattle that have no clinical signs and that are not suffering from infertility. One study published in 1978 isolated Ureaplasma from 88 of 163 clinically normal one- and two-year-old heifers from Alberta and Saskatchewan. Another study in Ontario isolated Ureaplasma from eight out of 34 clinically normal dairy cows. We still don’t understand why this bacteria causes disease in some instances and not in others.
Perhaps there are other factors involved that we don’t understand. It does appear that we isolate the organism in a much higher percentage of cows in situations where infertility is occurring.
In situations where we suspect Ureaplasma might be involved in causing infertility or abortions, there are two major principles involved in control. We want to prevent infection of the cow and treat those cows that may be infected.
Prevention primarily consists of treating bulls so that they are no longer carriers of the organism. There has not been a great deal of research into the best method of treatment, but the organism is usually sensitive to common antimicrobial drugs such as tetracycline, and veterinarians will probably recommend treating bulls with some form of antibiotics.
When dealing with potentially infected cows where artificial insemination is being used, antibiotics may be used in semen extenders to prevent transmission by artificial insemination. Veterinary textbooks also recommend the use of a “double rod” technique to prevent contaminating the insemination pipette when it passes through the vagina.
In dairy herds, some type of post-breeding infusion with tetracycline suspensions may be recommended to help control the effects of the infection and improve conception rates.
In beef cows, it may be possible to use injectable antimicrobials to treat potentially infected cows, but there is little scientific research on which therapy is best.
There has been little research on this potentially important reproductive disease since the late 1970s and 1980s in North America. Despite what we understand about the infection, we still don’t completely understand how it causes infertility and why it can be present in some cattle that are apparently clinically normal.
In the herd I visited, I am suspicious that it played a significant role in causing early embryonic death in the infected cattle, but it is always difficult to conclusively prove this theory.
It is something to consider in herds that are experiencing significant infertility issues or abortion problems.
If you suspect this condition exists in your herd, contact your local veterinarian. He can collect appropriate samples and send them to the diagnostic laboratory to determine if Ureaplasma is present.
The challenge still exists in determining if this is just part of the normal bacteria we find in the genital tract of cattle or if this bacteria is responsible for causing infertility. We probably always need to rule out the other potential causes of infertility before we finally reach a diagnosis.