Chapter 17 Diseases of the Eye
Conjunctivitis may have many causes—bacterial, viral (canine distemper virus or human influenza virus), or environmental (dust, debris, vapors). Cataract and lens luxations are believed to be inherited traits, and animals with these traits should not be used for breeding. Likewise, retinal atrophy may also be related to genetic causes or nutritional deficiencies (taurine). Typically, no treatment is suggested for these genetically based diseases.
Cataracts occur in rats and mice as both inherited and congenital lesions and secondary to other diseases and trauma. Nutritionally induced cataracts are also seen in laboratory rats fed increased levels of sucrose, xylose, or galactose.
Many rodents produce tears that contain the pigment porphyrin. These red-brown secretions are often mistaken for blood in the medial canthus and on the front paws of the animal. Both bacterial and viral diseases can be associated with conjunctivitis in rodents. Noninfectious causes include irritation from soiled bedding, malocclusion of overgrown incisors, and poor nutrition and hygiene.