Grappling With Mycoplasma

Mycoplasma bovis, or M. bovis, has been at the fringes of the cattle industry for a long time, it could be emerging as a serious disease organism for feeders and ranchers.

Montana cattle feeder Dan Vogel doesn't claim to be an expert on many things. But get him started on the topic of mycoplasma, and you'll find his insight into the cattle disease goes back more than a decade.

While Mycoplasma bovis has been at the fringes of the cattle industry for a long time, it could be emerging as a serious disease organism for feeders and ranchers. It's got a lot of each scratching their heads over the varying disease signs and different severities of infection.

The owner of Vogel Land and Cattle Co., Ballantine, MT, didn't know what he was facing when he saw the first signs of serious joint lameness in groups of younger calves.

“Not long after receiving some calves, we noticed they were packing their hind legs and dragging their shoulders,” Vogel says. “They kept getting worse. Instead of looking for a dry place to lie down, they'd look for a mud hole to cool themselves off.”

Infections soon showed up as pus pockets around the joints. The calves became nearly paralyzed, and were in such pain they quit coming to the feedbunk. He immediately called his vet, and they transported some of the sick animals 400 miles to the diagnostic lab at Fort Collins, CO.

“It turned out they were infected with the M. bovis organism,” he says.

After extensive research, Vogel began using a two-dose commercial mycoplasma vaccine made in Texas — one of the first vaccines for the disease. They've since not seen any serious outbreaks, but Vogel knows mycoplasma's etiology can be baffling and its progression a mixed bag.

Some health problems Vogel originally blamed on other diseases turned out to be mycoplasma-induced. In addition to the lameness, he says M. bovis showed up as middle-ear infections and severe respiratory disease.

“We still use a vaccine, but still have an occasional mycoplasma case,” Vogel says.

Outside of vaccinating for mycoplasma, Vogel thinks producers see fewer M. bovis-caused problems if calves are effectively immunized against the common viral diseases.

“We don't see mycoplasma in calves with some exposure to other diseases, and properly vaccinated for both the bacterials and virals at the ranch,” Vogel says. He adds an effective mineral program is essential in helping an animal's immune system fight this disease.

A whole lot hotter

Leonard “Buzz” Lindsay, DVM, Garberville, CA, has also fought M. bovis. He thinks it's the primary cause of a respiratory-disease outbreak in his northern California cattle herd. He's initiating an in-depth investigation into the disease.

“My suspicion is this disease is a lot hotter than we thought,” Lindsay says. “It appears to be a big and growing problem.”

While mycoplasma seems to pop up in new areas with increasing virulence, some think the organism is more opportunist, setting up susceptible cattle to infection from other viral and bacterial pathogens like the bovine viral diarrhea (BVD) virus.

More than 20 species of mycoplasma, ureaplasma and acholeplasma have been isolated from cattle with different diseases. All these species have been referred to as mycoplasmas. The textbooks say they generally play a secondary role in infections, most often exacerbating pre-existing disease, but it's been shown M. bovis can play a primary role.

“The line we're hearing out here though, is M. bovis isn't a very powerful organism,” Lindsay says. “But, in my case, it's been isolated as the cause of some chronic ‘lungers’ — and we can't find significant evidence of other pathogens.”

Primary or secondary agent

John Maas, University of California-Davis DVM, says whether M. bovis is an opportunist or a primary disease agent might be just a semantic argument.

The disease has been reported to occur in pre-weaned calves as early as 4 days of age up to 10 weeks. It's also been found in post-weaned calves up to 18 months of age. Maas says wherever there are cattle, you'll find mycoplasma.

“It's a pretty universal organism,” he says. “The damage the organism does to a bovine is dependent on where it decides to set up shop.”

Maas says the damage caused by M. bovis is highly variable. Conditions may include pneumonia, mastitis and arthritis. Meningitis, otitis media (middle-ear infection), kerato-conjunctivitis (pinkeye), vaginitis and/or fetal abortion are also mentioned when discussing mycoplasma.

Maas describes M. bovis as a member of a “gang” of livestock pathogens that continually pick on cattle. After talking to producers like Vogel and Lindsay, you learn tracking this disease is like sorting out who threw the first punch in a gang fight.

“Such viruses as BVD certainly can be the primary problem,” Maas explains. “In a feedlot or stocker situation, BVD does a great job in setting an animal up for super-infection by mycoplasma. Then other bacteria like haemophilus, mannheimia and pasturella can come in and do their damage.”

He agrees the industry — especially backgrounders and feeders — should pay more attention to mycoplasma.

“It's getting to be more common; it's something producers and veterinarians should be talking more about,” Maas adds.

Difficulty in diagnosis

Traditionally though, mycoplasmas have been hard to diagnose, especially in live animals.

“It's a tough organism to grow in the lab,” Maas says. The newer DNA-based analytical tests and antigen capture tests will help detect this disease instead of having to grow it in the lab.

“This isn't a group of organisms we're going to get rid of,” he says, “but the more we can identify M. bovis, the more we can eliminate other risk factors from the equation.”

A University of Missouri-Columbia (UM-C) College of Veterinary Medicine report says M. bovis can be cultured from most cattle. Thus, it's important to realize infection doesn't equal disease. This is important to remember when culturing M. bovis from sick or dead animals, as other evidence must also point toward the organism before it can be cited as contributing to an animal's death.

The UM-C report also notes, while it's possible for M. bovis to cause pneumonia in cattle by itself, it's almost always secondary to typical pneumonia caused by a chain reaction of stress, viral infection and pasteurella (Mannheimia) infection.

Treatment after treatment

Whether or not mycoplasma is a secondary invader following weakness caused by other bacterial or viral infections, Vogel and Maas agree treating calves for the disease can be pricey.

M. bovis likes to harbor in places where there's low blood flow, like the joints and middle ear. Once there, it runs wild,” Vogel explains. “You have to pour the medication into these animals — and I mean pour it into them — before you get enough antibiotic in the bloodstream for a response.”

Some older antibiotics, like tetracyclines, are often cited as more specific against mycoplasma than some newer antimicrobials. This can help reduce treatment costs, although when treating individual animals for M. bovis, responses tend to be slower than with most other bacterial diseases.

“It takes closer to 7-10 days than 3-4 days to see a response,” Maas explains. “It's a disease that argues for good veterinary backup to keep monitoring animals as they're treated, and after treatment.”

Vogel says he had little luck fighting M. bovis using tetracyclines early on — but some success with off-label use of lincomycin, a swine antibiotic approved by his vet. Lately he's been treating mycoplasma with spectinomycin and sometimes “high doses” of penicillin.

“But, you really don't want to get to the point where you're treating calves for mycoplasma,” he warns. “Once you're treating for it, you're way too late; the damage is done and you'll pour a lot of money into treatment.”

Vogel agrees treating mycoplasma isn't a short-term deal. “It takes more like 10-14 days of treatment; if you don't watch out, you'll be slammed with a $100-$150/head medication bill before you know it.”

The vaccination puzzle

Maas' experience is vaccination tends to be a questionable proposition. That's because vaccines are relatively new, and there are still a lot of unanswered questions as far as vaccinating for this disease. More research into vaccines is needed, he says.

The UM-C report says controlled trials have shown no beneficial effect, or even a detrimental effect of vaccination.

UM-C's observation is that it's possible a vigorous vaccination program (possibly with four or more doses) may provide protection of short duration, but apparently even this evidence isn't supported by field trials.

Ron Skinner, DVM, Hall, MT, is another producer/vet on mycoplasma's trail. He says the disease is difficult because its causative organism has no cell wall.

He says there are many questions to be answered regarding the M. bovis ability to mutate and become resistant to antibiotics. Skinner also says its relationship with other organisms is a very important part of sorting out mycoplasma treatment and prevention protocol.

“No question, mycoplasma is a big deal for a lot of ranchers and cattle feeders,” Skinner says. “It's a complicated organism that seems to change easily and adapt to different conditions. As an industry we really need to take a new and hard look at this disease.”