About two percent of cattle with pink eyes remain permanently and completely blind in the affected eye.
Conjunctivitis in cattle is usually a bacterial infection. Bovine conjunctivitis can also negatively affect a cow’s ability to give milk and can cause weight loss, starvation, blindness and injury. It is basically caused by the infection of Moraxella bovis bacteria. Conjunctivitis in cattle can cause light sensitivity, corneal ulceration, and corneal rupture.
There are many strains of the Moxarella bovis bacterium, which is responsible for conjunctivitis in cattle, and there is currently no vaccine to protect against infection. It is generally believed that the toxins produced by M. bovis are responsible for the severe damage that conjunctivitis can cause to the ocular membranes of cows.
Some conditions can make cattle more prone to conjunctivitis. Any foreign object that irritates the eyes can make cattle more vulnerable to this disease. Bright light and dusty conditions can also contribute to the development of severe bovine conjunctivitis. Flies are often implicated in the development of conjunctivitis infections in cattle, as they can spread the M. bovis bacteria from one animal to another.
The first symptom of conjunctivitis in cattle is usually increased eye secretions. Tears may flow freely in animals showing early signs of bovine conjunctivitis. Conjunctivitis can also make the animal’s eyes more sensitive to light, so cows with this infection may begin to squint or blink excessively. The conjunctiva, or eye membranes, are often inflamed.
As the disease progresses, corneal ulcers can form. Ulcers usually appear as white spots on the surface of the eye. In milder cases of infection, the ulcer may begin to heal on its own. In more severe cases, the ulcer can expand in size, causing the cornea to rupture. If the cornea breaks, fluid from inside the eye can leak out and the remaining eye tissue can collapse into the eye socket.
In most cases, cattle recover from conjunctivitis without permanent vision loss. Recovery is usually evident in the final stage of the disease, when the surface of the eye becomes excessively red, then bluish and dull, and finally returns to normal. About two percent of cattle with pink eyes remain permanently and completely blind in the affected eye. If corneal scarring occurs, a bluish area may remain visible in the center of the eye after the animal has recovered. Full recovery from conjunctivitis in cattle takes three to five weeks in most cases.