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6 Signs Mycoplasma Might be Lurking
in Your Cattle

Some of the calves you brought in a month ago have been pulled for pneumonia, but they aren’t responding well to treatment. Now you’ve noticed a few are showing signs of arthritis. Is it possible you got more than you planned with that new group of calves?

If these symptoms remind you of animals in your herd, you might be facing a Mycoplasma infection.

“Mycoplasma is a more common pathogen than we realize,” says Veterinarian Roger Winter, AgriLabs. “Infected animals may slowly deteriorate and become chronic poor-doers, or even die. Since treatment is often unsuccessful, prevention is key.”

There are several Mycoplasma species, but the most problematic in beef cattle is Mycoplasma bovis. Research tells us that half of cattle with normal lungs carry M. bovis, but this pathogen is found in a whopping 98% of cattle with chronic pneumonia.1

In fact, M. bovis is an increasingly recognized cause of disease in feedlot cattle. Affected cattle invariably have a lung lesion, and 40%-60% also may develop arthritis and tendon inflammation that cause severe lameness.2

Morbidity rates in these cattle may reach 80%, with mortality rates often exceeding 20%.

How does Mycoplasma cause damage?
Mycoplasma is the smallest free-living pathogen in animals and is part of the normal flora in the upper respiratory tract.

This pathogen attaches itself to mucosal surfaces, then invades tissue and liberates toxins that can cause severe tissue damage. It also moves through the bloodstream to other tissues (e.g., joints).

Beyond damaging tissue, Mycoplasma can suppress an animal’s immune system and play a part in increasing the severity of disease caused by other pathogens.

“M. bovis has a key role in the bovine respiratory disease (BRD) complex, with infected cattle having milder clinical symptoms that progress slowly — a ‘smoldering’ pneumonia,” says Winter. “Treatment typically isn’t effective, which means more re-treats, chronics and poor responders — and higher costs. That’s why recognizing signs of this insidious organism is so important.”

What are signs of an M. bovis infection?
Symptoms of disease associated with M. bovis commonly are seen in calves weighing 300 to 600 pounds (lb.), but also are found in heavier cattle. These symptoms often appear three to four weeks after arrival, especially after commingling, crowding, and wet and cold weather.

Since M. bovis quickly can become a pen problem, look for these telltale signs that M. bovis might be gaining a foothold in your operation:

  1. 1) Increased respiration. Faster breathing often is a sign of illness; some calves might struggle to draw air into their lungs and force air out.
  2. 2) Frequent, hacking cough. These coughs are noticeably harsh and can become persistent.
  3. 3) Discharge from the nose. A runny nose is sometimes accompanied by watery eyes.
  4. 4) Fever. Some animals may have temperatures of 104° F, especially when other pathogens are also present. As cases become chronic, fever may be minimal.
  5. 5) Decreased appetite. A loss of appetite can lead to weight loss.
  6. 6) Arthritis. The first cases usually appear a week after pneumonia is observed, and can involve swelling around one or more joints.

“Cattle infected with M. bovis-related BRD typically show signs of pneumonia three to four weeks after arrival, and do not respond well to treatment,” says Winter. “One or two weeks later, a number of the pneumonia cases will develop signs of arthritis. Most deaths occur three to six weeks after arrival.”

How can you manage Mycoplasma?
While few infected animals will exhibit all six signs, the presence of symptoms means Mycoplasma quickly can escalate into a problem for the entire group.

Mycoplasma spreads easily via coughing, nasal secretions, and direct contact with infected animals, fences, feedbunks, water troughs and milk. It’s opportunistic, often contributing to underlying bovine viral diarrhea (BVD) infections and BRD.

“Metaphylaxis of problem pens might be beneficial if done early, but treating chronics usually is futile,” Winter says. “Even though a few antibiotics show some laboratory effectiveness against Mycoplasma, treatment seldom is very rewarding.”

The key to keeping Mycoplasma from gaining ground in your herd is using the same good-management practices that keep other respiratory diseases in check:

What role can vaccines play?
“Immunosuppression associated with BVD infection has been shown to predispose animals to Mycoplasma infections, so proper vaccination with viral vaccines like Titanium® is important,” Winter says. “Vaccinating with MpB Guard® also may help reduce the incidence and severity of disease.

“Reaching out to your veterinarian to develop a prevention strategy is the best way to keep Mycoplasma from creating chronic problems with your herd’s health and profitability.”

1Gagea, M.I., Bateman, K.G., Shanahan, R.A., van Dreumel, T., McEwen, B.J., Carmen, S., Archambault, M., Caswell, J.L. 2006. Naturally occurring Mycoplasma bovis associated pneumonia and polyarthritis in feedlot beef calves. Journal of Veterinary Diagnostic Investigation 18:29-40.
22010. The Merck Veterinary Manual, 10th ed. Page 1325.

Editor’s Note: Article first distributed in AgriLabs’ Healthy Difference Insights newsletter
(Vol. 3, Issue 1).

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