Pinkeye in Beef Cattle
Megan Van Emon, Extension Beef Cattle Specialist
Pinkeye is one of the most common diseases in beef cattle. It is highly contagious and can spread easily throughout the herd if left untreated. Due to the regular moisture we have been receiving and the tall grass, pinkeye may be more prevalent this year.
Moraxella bovis is the primary bacteria species causing pinkeye. Typical symptoms are inflammation of the cornea and conjunctiva, causing the eye to weep excessively. Affected cattle will keep their infected eye closed due to pain and to avoid bright sunlight. If left untreated, ulceration of the cornea can occur, which may lead to blindness in the infected eye. Pinkeye can also negatively impact calf growth and performance by reducing feed intake.
There are 3 stages of pinkeye:
Stage 1: The eye will have increased light sensitivity and weep excessively. As the pinkeye progresses in stage 1, an ulcer (white spot) will form in the middle of the cornea. The cornea will also appear gray due to the increased inflammation.
Stage 2: The stage 1 signs will continue, and the ulcer will begin to spread across the entire cornea. The cornea will appear cloudy as inflammation continues to increase. As stage 2 progresses, the blood vessels on the outer edge of the cornea will spread across the cornea to aid in healing. The outer edge of the cornea will appear pink, which provides the disease name sake.
Stage 3: The ulcer will encompass the majority of the cornea and inflammation will move into the inner eye. As this inflammation continues, the eye will fill with fibrin, giving the eye a yellow appearance, surrounded by the pink outer edge of the cornea.
Pinkeye is readily spread throughout the herd by face flies. Face flies can spread the disease to several animals throughout the day because they spend little time on the cattle. Therefore, best control of pinkeye is prevention. Having a good fly control program can help mitigate the spread of pinkeye throughout the herd.
If calves in the herd have pinkeye, the typical treatment plan is a long-acting antibiotic and protecting the eye from sunlight. Consult your veterinarian to determine the best antibiotic to use for pinkeye. Applying an eyepatch to the infected calves is also crucial in the treatment plan because sunlight activates enzymes in the eye which can increase pinkeye damage to the cornea.
If pinkeye is prevalent in the herd year after year, consult your veterinarian to determine if a pinkeye vaccine may help. There have been mixed results on the use of pinkeye vaccines due to the multiple bacterial species that may be the cause. Bacterial cultures may need to be collected to determine if the vaccine will be effective in reducing the incidence of pinkeye.