Figure 6. The numbers of M. bovis recovered in the Eustachian tubes and tympanic bullae were dramatically higher in orally-inoculated than in transtracheally-inoculated calves.

A t 14 days after oral- (N = 8) or transtracheal-inoculation of calves (N = 5), mycoplasma numbers in corresponding a) Eustachian tubes and b) tympanic bullae were determined (left and right sides are shown separately for each inoculated calf). Mycoplasmas were not recovered from any tissue of any control calf (N = 8). (data not shown). High numbers of mycoplasmas were recovered from the ears of several animals in the mycoplasma-inoculated group. c) In all animals where mycoplasmas were recovered from the tympanic bullae, organisms were recovered from the corresponding Eustachian tube; however, there were several animals (outlined in dashed box) where organisms were recovered from the Eustachian tubes and not the corresponding tympanic bullae. Data represent all orally (N = 8) and transtracheally (N = 5) inoculated calves, with left and right sides shown separately for each calf. d) Ears with the highest lesions scores in tympanic bullae also had high lesion scores in corresponding Eustachian tubes. Data represent all orally (N = 8) and transtracheally (N = 5) inoculated calves, with left and right sides shown separately for each calf For visual purposes, tissues with identical scores have been shown with values slightly offset. Asterisks “*” denotes a significant difference between groups (P≤0.05).