According
to vet Dr Tim Potter from Westpoint Veterinary Group, Mycoplasma
bovis has emerged as an
important pathogen of calves worldwide [ref
2].
"It is associated with a number of clinical presentations
including respiratory disease, otitis media and arthritis," he
explains.
"The
role of Mycoplasma bovis
in pneumonia is well established and there are a number of reports in
the literature of respiratory disease outbreaks where it was the
predominant bacterium isolated. However, as with most causes of
pneumonia, colonisation by Mycoplasma
bovis alone is not always
sufficient to cause disease and it may present in combination with
other respiratory pathogens."
For
other pathogens, the surveillance found 83% of samples positive for
Para-influenza 3 virus (Pi3v), 76% Bovine Respiratory Syncytial virus
(BRSv), 32% IBR, and 25% for BVD. Apart from BVD, which saw a
three-point reduction from 28% the previous year - these show little
change from 2013.
In
pneumonia outbreaks involving Mycoplasma
bovis, many of the
clinical signs are similar to those caused by other pneumonia
pathogens, according to Zoetis vet Carolyn Hogan: Coughing, raised
temperature, rapid breathing and lethargy.
"This
can make it difficult for farmers and vets alike to identify
Mycoplasma bovis
as a possible cause of disease based on clinical signs alone, unless
calves are also showing some of the other distinguishing signs
associated with Mycoplasma
infection,” she says.
"These
include ear infections, head shaking or tilting, and arthritis. Poor
response to treatment, with resulting chronic respiratory cases, may
also be suggestive of Mycoplasma
infection. For a definitive diagnosis, of course, analysis of blood
or respiratory tract mucous is required."
Whilst
vaccination protection is available against the viruses (BRSv, Pi3v,
BVD and IBR) and Mannheimia
(Pasteurella) haemolytica,
Carolyn Hogan points out that there is no ‘off the shelf’ vaccine
available for Mycoplasma
bovis. She adds that
treatment can be challenging due to the insidious nature of disease,
and lack of effectiveness of some antibiotics.
Once
Mycoplasma bovis
is present on a farm, Carolyn cautions that eradication can be very
difficult. "It can be transmitted in milk from carrier cows, and
in saliva among calves, particularly when multiple animals suckle the
same teat feeders," she explains.
"Minimising
this pathogen's impact on health and productivity relies on reducing
its exposure to susceptible animals and maximising their resilience
against it. For a comprehensive programme of control measures,
farmers should consult their vet."
Ms
Hogan suggests that such a programme is likely to include, for
example: Finding out your farm's Mycoplasma
bovis status; effective
biosecurity; not feeding infected milk; ample ventilation for adults
and youngstock alike; rapid spotting of sick animals, isolation and
vet-prescribed treatment; vigilance for poor response to treatment
and development of chronic cases; vaccination against main viral
pneumonia pathogens; and low stress through good stockmanship.
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References:
1 Zoetis,
April 2015. Pneumonia pathogen surveillance. Data on file.
2 Dr
Tim Potter, October 2014. Mycoplasma bovis in calves.
Presentation at BCVA Congress. Westpoint Veterinary Group.
