Diseases of the eye

Infectious Bovine Keratoconjunctivitis Pink Eye Infectious keratoconjunctivitis of cattle, sheep, and goats is characterized by blepharospasm, conjunctivitis, lacrimation, and varying degrees of corneal opacity and ulceration. Infectious keratoconjunctivitis of cattle, sheep, and goats is characterized by blepharospasm, conjunctivitis, lacrimation, and varying degrees of corneal opacity and ulceration.

Etiology In cattle, Moraxella bovis with multiple serovars is the most commonly recognized cause of infectious keratoconjunctivitis. Most other ocular infections of cattle are characterized by conjunctivitis and minimal or absent keratitis. In cattle, Moraxella bovis with multiple serovars is the most commonly recognized cause of infectious keratoconjunctivitis. Most other ocular infections of cattle are characterized by conjunctivitis and minimal or absent keratitis. In sheep, infection with Chlamydophila In sheep, infection with Chlamydophila (Chlamydia ) pecorum is most common. Nonchlamydophilal infections may be caused by rickettsia-like organisms ( Colesiota conjunctivae), Mycoplasma spp (Chlamydia ) pecorum is most common. Nonchlamydophilal infections may be caused by rickettsia-like organisms ( Colesiota conjunctivae), Mycoplasma spp

Clinical Findings The disease usually is acute and tends to spread rapidly. One or both eyes may be affected. In cattle, dry, dusty environmental conditions; shipping stress; bright sunlight; and irritants such as pollens, grasses, and flies tend to predispose to or exacerbate the disease. Flies also serve as vectors. In all species, young animals are affected most frequently, but animals of any age are susceptible The disease usually is acute and tends to spread rapidly. One or both eyes may be affected. In cattle, dry, dusty environmental conditions; shipping stress; bright sunlight; and irritants such as pollens, grasses, and flies tend to predispose to or exacerbate the disease. Flies also serve as vectors. In all species, young animals are affected most frequently, but animals of any age are susceptible

Clinical findings cont.. The initial signs are photophobia, blepharospasm, and epiphora; later, the ocular discharge may become mucopurulent. Conjunctivitis, with or without varying degrees of keratitis, is always present. In sheep and goats, concurrent polyarthritis may be present The initial signs are photophobia, blepharospasm, and epiphora; later, the ocular discharge may become mucopurulent. Conjunctivitis, with or without varying degrees of keratitis, is always present. In sheep and goats, concurrent polyarthritis may be present

Lesions Lesions vary in severity. In cattle, 1 or more small ulcers occur near the center of the cornea often preceded by cloudiness of the central cornea. Initially, the cornea around the lesion is clear, but within a few hours a faint haze appears that subsequently becomes denser Lesions vary in severity. In cattle, 1 or more small ulcers occur near the center of the cornea often preceded by cloudiness of the central cornea. Initially, the cornea around the lesion is clear, but within a few hours a faint haze appears that subsequently becomes denser Infectious bovine keratoconjunctivitis with corneal ulceration in the cow. Courtesy of Dr. Kirk N. Gelatt

Diagnosis: In all species, presumptive diagnosis is based on ocular signs and concurrent systemic disease. It is important to distinguish that the lesions are not due to foreign bodies or parasites In all species, presumptive diagnosis is based on ocular signs and concurrent systemic disease. It is important to distinguish that the lesions are not due to foreign bodies or parasites

Prevention and Treatment: Good management practices are of paramount importance in reducing or preventing spread of infection in cattle, sheep, and goats. Separation of infected animals is beneficial when possible. Good management practices are of paramount importance in reducing or preventing spread of infection in cattle, sheep, and goats. Separation of infected animals is beneficial when possible. M bovis is susceptible to a variety of antibiotics. Because antibiotic susceptibility may vary in different geographic locations, bacterial culture and susceptibility testing is advised. Ampicillin, penicillin, gentamicin, and kanamycin can be injected subconjunctivally; best results are obtained with injection into the bulbar conjunctiva. Oxytetracycline is generally considered the drug of choice for systemic therapy because it is concentrated in corneal tissue M bovis is susceptible to a variety of antibiotics. Because antibiotic susceptibility may vary in different geographic locations, bacterial culture and susceptibility testing is advised. Ampicillin, penicillin, gentamicin, and kanamycin can be injected subconjunctivally; best results are obtained with injection into the bulbar conjunctiva. Oxytetracycline is generally considered the drug of choice for systemic therapy because it is concentrated in corneal tissue

Ocular squamous cell carcinoma (cancer eye) is the most common neoplasm of cattle. It results in significant economic loss due to condemnation at slaughter and a shortened productive life. It occurs more frequently in the Bos taurus than the Bos indicus breeds, and is seen most often in Herefords, less often in Simmentals and Holstein-Friesians, and rarely in other breeds is the most common neoplasm of cattle. It results in significant economic loss due to condemnation at slaughter and a shortened productive life. It occurs more frequently in the Bos taurus than the Bos indicus breeds, and is seen most often in Herefords, less often in Simmentals and Holstein-Friesians, and rarely in other breeds

Etiology The etiology is multifactorial with heritability, sunlight, nutrition, eyelid pigmentation, and perhaps viral involvement playing roles The etiology is multifactorial with heritability, sunlight, nutrition, eyelid pigmentation, and perhaps viral involvement playing roles

Lesions Bilateral involvement varies but can be as high as 35%. Eyelid and conjunctival pigmentation are highly inheritable and can reduce the frequency of lid squamous cell carcinomas, but have less effect on the development of tumors of the conjunctiva and nictitating membrane. The cancerous or precancerous lesions are bilateral or multiple in the same eye. Bilateral involvement varies but can be as high as 35%. Eyelid and conjunctival pigmentation are highly inheritable and can reduce the frequency of lid squamous cell carcinomas, but have less effect on the development of tumors of the conjunctiva and nictitating membrane. The cancerous or precancerous lesions are bilateral or multiple in the same eye. The lesions usually begin as benign, smooth, white plaques on the conjunctival surfaces; they may progress to a papilloma and then a squamous cell carcinoma, or go directly to the malignant stage The lesions usually begin as benign, smooth, white plaques on the conjunctival surfaces; they may progress to a papilloma and then a squamous cell carcinoma, or go directly to the malignant stage

Treatment Squamous cell carcinomas may respond to excision, cryotherapy, hyperthermia, radiation therapy, and immunotherapy, or a combination of these therapies. Surgical excision is indicated for small lesions or for debulking the larger lesions before cryotherapy or hyperthermia. Squamous cell carcinomas may respond to excision, cryotherapy, hyperthermia, radiation therapy, and immunotherapy, or a combination of these therapies. Surgical excision is indicated for small lesions or for debulking the larger lesions before cryotherapy or hyperthermia. For advanced lesions confined to the globe, enucleation is recommended. When adjacent tissues are affected, removal of the globe and all orbital contents (exenteration) should be performed For advanced lesions confined to the globe, enucleation is recommended. When adjacent tissues are affected, removal of the globe and all orbital contents (exenteration) should be performed