4 - Eye and ear

Abstract

A daunting task in the ophthalmic pathology is the need to be familiar with the ever-growing list of specific ocular syndromes, the correct identification of which has huge significance in terms of therapy and prognosis. This chapter discusses the gross pathology of eye and ear for correct diagnosis that requires the correlation of the lesion with the age, breed, and specific clinical features of the disease. This chapter describes several ocular developmental defects that are common in domestic animals and include defective organogenesis, such as anophthalmos and cyclopia; defective differentiation such as anomalies of mesenchyme, anomalies of neurectoderm, and anomalies of surface ectoderm; and ocular adnexa such as eyelids and lacrimal system. Corneal diseases discussed in this chapter are corneal edema, corneal wound healing, corneal dystrophy, corneal degeneration, and keratitis, such as pannus keratitis, keratoconjunctivitis sicca and desiccation keratitis, herpetic keratitis of cats, feline eosinophilic keratitis, and mycotic keratitis. The chapter discusses diseases associated with lens (ectopia lentis, cataract), uvea (uveitis and glaucoma), optic nerve sclera, and orbit. Further, overview of retinal histopathology, retinal separation, retinal degeneration, inherited retinal atrophies in dogs, photoreceptor degenerations and dysplasias in cats, inherited night blindness in horses, light-induced retinal degeneration, nutritional retinopathy ( hypovitaminosis A, taurine-deficiency retinopathy), and toxic retinopathies are also discussed. The chapter discusses ocular neoplasia that includes eyelid and conjunctival neoplasms (squamous cell carcinoma, meibomian adenoma, and conjunctival tumors), melanotic tumors of the eye, tumors of ocular neurectoderm, feline post-traumatic sarcoma, optic nerve tumors, primary orbital neoplasms, and tumors metastatic within the globe and orbit. The diseases associated with ear are divided into three categories: external ear (otitis externa), middle ear (otitis media), and inner ear (otitis interna, deafness, vestibular dysfunction, neoplasms, and lesions).