TRACHEAL WASHES FOR THE DIAGNOSIS OF
The impact a tracheal wash may have on the diagnosis
of bovine respiratory syncytialvirus (BRSV) infection
often is not fully realized. The procedure is easy to
perform, but seldom are tracheal wash samples received
at the diagnostic laboratories. In one study, positive
BRSV fluorescence was demonstrated on cells recovered
from tracheal lavages of 20 of 42 calves, while BRSV could
be isolated in only 6 nasal swabs from the same 42 animals
(ActaVet Hung 1987;35:475-7). In another study, 21 of
32 lavages were positive by FA, and 17 of those 21 were
also cell culture positive. After experimental inoculation
of calves with BRSV, FA tests were positive
for 12-18 days. Virus isolation attempts from nasal
swabs collected from these experimentally infected animals
were consistently negative (Am J Vet Res 1986;47:143-7).
A similar study in young children infected with a human
respiratory syncytial virus (RSV) had comparable results:
49 tracheal washes, but only 27 nasal swabs from 121 children
were positive for RSV virus on culture. Fifty-two washes,
but only 12 swabs were FA positive (DiagnMicrobiolInfDis
The virus is very labile and inactivates quickly. Calves
mount a rapid immune response. Antibodies tend to neutralize
the virus as the disease progresses, and the likelihood
of isolating BRSV decreases rapidly. To perform a tracheal
wash on a bovine, pass a sterile gastric tube through
the nasal cavity into the lungs. Infuse 50-60 ml of sterile
media that contains antibiotics, such as viral transport
media or Hank's salt solution, and immediately withdraw
the wash solution. In general 15-30 ml can be recovered.
Submit the tracheal wash sample on ice to the laboratory
for FA testing and virus isolation.
This procedure is not just a bovine technique.
Tracheal washes and lung lavages have applications for
all domestic animals (use smaller volumes in smaller animals)
and the diagnosis of other viral diseases.
Charles A. Baldwin Reprinted with permission of author
Charles A. Baldwin, Veterinary Diagnostic and Investigational
Laboratory, Tifton, GA