Clinical Examination of Farm Animals - CYF MEDICAL DISTRIBUTION

CHAPTER 7
Figure 7.10 Bronchoalveolar lavage.
neck until there is resistance: the tube is now at the
bifurcation of the major bronchi (the coryna) of the
trachea. The 50 ml catheter syringe containing 20 ml
of warm sterile saline is attached to the proximal end
of the tube and the saline is injected. Suction is immediately
applied to the syringe to withdraw as much of
the injected saline as possible. About 10 ml is usually
retrieved. Gross examination may reveal cellular
debris, suggesting inflammatory changes in the trachea
and bronchi, and occasionally lungworm larvae
may be observed.
Some of the refluxed saline should then be decanted
into the viral transport medium and some
placed in a sterile tube for bacterial culture. Afurther
aliquot should be placed in EDTA for cytological examination.
Analyses may include IFAT for PI3, RSV,
IBR and BVD, and bacterial culture for Pasteurella
and Haemophilus.
A modification to the technique to avoid contamination
of the sample by nasopharyngeal commensels
is to place a short wider bore 8 mm tube through the
ventral meatus to the entrance of the glottis and feed
the 6 mm collection tube through the wider bore
tube, thus avoiding contamination of the collecting
tube.
Diagnosis of lungworm
Lungworm infestation is an important disease
affecting all ages of cattle. Examination of faeces, bronchoalveolar
samples and oral saliva samples for larvae may
confirm a diagnosis of lungworm. Exposure to lungworm
can also be confirmed by an ELISA test on the
patient’s serum.
Acute and convalescent sera
Rising serological titres may give a retrospective indication
of the possible causal agent(s) of an outbreak
of viral pneumonia. Serological samples are taken
from five affected animals at the time of the outbreak
followed by repeat samples from the same animals
4–6 weeks later. A rising titre from weaned animals
indicates recent antigenic exposure.
Nasopharyngeal swab
Bronchoalveolar samples are better than nasopharyngeal
swabs in identifying the aetiological agents of pneumonia
in cattle, although nasophyrangeal swabs have been
used successfully to identify PI3 and IBR infections.
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