Mycoplasma bovis: Overview of the disease and individual-animal…

Presented by presented by Jeff Caswell, DVM, DVSc, PhD, Dipl. ACVP

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CE credit: 1

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Questions

1. Why doesn’t Mycoplasma bovis disease respond to treatment with cephalosporins? *

Produces beta-lactamase

Doesn’t have a cell wall

Proteins in the membrane pump antibiotics out of the bacteria

Cephalosporins can’t penetrate the bacterium's membrane lipoproteins

2. Which is considered a common method by which M. bovis is transmitted among cattle? *

Direct contact with infected animals

Spread by aerosols across long distances

Inhalation of dust from the soil

Spread by boots and coveralls

3. M. bovis enters the middle ear (to cause otitis media) via: *

Vestibulocochlear nerve

Blood

External ear canal

Auditory (eustachian) tube

4. How does M. bovis enter the joint to cause lameness? *

Penetrating injury

Blood

Tendon sheath

From the adjacent bone

5. Which is the characteristic postmortem lesion in the lung, caused by M. bovis? *

Cranioventral lung is red-purple, firm and contains tiny tan nodules

Cranioventral lung is diffusely red-purple, firm and contains irregularly shaped non-raised tough lesions, each surrounded by a white rim

Cranioventral lung is red-purple, firm and contains tiny tan nodules filled with pasty or crumbly material

Cranioventral lung is red-purple, firm and contains tiny tan nodules filled with liquid pus

6. Which clinical signs are typical of otitis media caused by M. bovis? *

Seizures

Ear twitching

Head tilt and ear droop

Crusted lesions on the pinna

7. When can you easily locate the tympanic bullae, so they can be easily opened as part of a postmortem examination? *

At the end of the external ear canal

Dorsolateral to the occipital condyles

Within the cranial vault, ventral to the cerebellum

Ventral surface of the skull, cranial and slightly lateral to the occipital condyles

8. . Which best describes the occurrence of M. bovis disease in the first 2 months after beef calves from different sources arrive to a feedlot? *

Infection is infrequent, most infected animals have disease

Infection is infrequent, minority of infected animals have disease

Infection is widespread, minority of infected animals have disease

Infection is widespread, most infected animals have disease

9. How do you interpret a positive qPCR test for M. bovis from a nasal swab of a diseased calf? *

M. bovis is the cause of disease in this calf

Knowledge of clinical signs (and postmortem lesions, if available) is used to determine its significance to the disease in this calf

qPCR tests cannot distinguish M. bovis vs. other mycoplasmas, so the test is not useful

The finding is irrelevant because M. bovis is a commensal that does not cause disease

10. Other than vaccination, what are the principles of controlling M. bovis disease in cattle herds? *

Avoid bringing M. bovis into the herd

Promote health and resilience of the herd

Minimize coinfections and inflammation

Prevent clinical cases from infecting other animals

All of the above are correct