Page 310 - Clinical Manual of Small Animal Endosurgery

298 Clinical Manual of Small Animal Endosurgery

Fig. 10.19 Lateral tracheal collapse due to suspected chondromalacia in a
pet rabbit.

Tracheoscopy
Most small pet mammals have a very narrow-diameter tracheal lumen.
This makes bronchoscopy (either with a flexible or rigid endoscope) far
more risky in these species, as it results in significant luminal reduction.
It should also be considered that many rabbits have a degree of lung
pathology that may not be clinically apparent, as they are a prey species
and will hide signs of illness. Brief intermittent tracheoscopy with a 2.7
or 1.9 mm endoscope is possible. Oxygen should always be immediately
available in case of a respiratory crisis. The author has used tracheoscopy
to diagnose symptomatic lateral tracheal collapse due to suspected chon-
dromalacia in pet rabbits (Fig. 10.19). This condition manifested as
recurrent tracheitis and a stridorous noise.

Otoscopy
A 1.9 or 2.7 mm endoscope can be used for otoscopic examination in
ferrets and rodents. However, the author has found otoscopy to be
impractical in many rabbits with otitis externa or otitis media. Both the
horizontal and vertical cartilages of the external ear canal are vertical in
rabbits, and extremely narrow. The ear canal is highly sensitive, particu-
larly to any stretching, which is painful in rabbits. Chronic inflammation
only exacerbates this. Rabbits have thick, tenacious pus, and also often
appear to have thick cerumen. Not only are pus and these thick
ceruminous/waxy deposits difficult to differentiate visually, both being
white, but attempts to flush this thick debris from the ear canal very
easily result in tympanic-membrane rupture, as the inserted cannula seals
the narrow ear canal. Rough otoscopy can also result in tearing of the
ear canal at the small junction of the cartilage rings and this may lead
to leakage of wax into the peri-auricular and subcutaneous tissues and