Last month we discussed common flies that put the “pest” in “pester” for cattle in the heat of the summer. This month, let’s explore a secondary summer cattle issue that comes with flies: infectious bovine keratoconjunctivitis, commonly known as pinkeye.
Flies to Blame
Most people understand flies transmit disease, and pinkeye in cattle is a great example. Feeding on tears, face flies easily transmit bacteria to the eye.
In the specific case of pinkeye, bacteria of the genus Moraxella are responsible. These gram-negative, rod-shaped bacteria love to grow in the tissues of the eye. Here they infect mainly the eyelids and the cornea, which explains the clinical signs you see with these infections.
Cattle with pinkeye typically first show squinting and tearing, as the animal becomes sensitive to sunlight. As the case progresses, the cornea, or outside layer of the eyeball, will become cloudy. Sometimes the cornea will ulcerate, and a divot will show on the eyeball.
In severe cases, the eye can either rupture or become so scarred that the animal loses vision. In other cases, a permanent scar will result. This appears as a white spot on the eyeball.
Treatment for Pinkeye
Some cattle breeds are more susceptible to pinkeye than others. These are the typical “white-faced” breeds such as Herefords and Hereford-crosses, Charolais and Holsteins.
Pinkeye most frequently affects cow/calf herds. A farmer may notice one infected animal and then after a few days, many more within the herd will also succumb, such that it quickly becomes a herd-wide issue. For this reason, it’s important to initiate treatment as soon as you notice a single animal with this condition. That way, you’ll help curb the contagion before it spreads to your entire herd.
Early treatment is also necessary from a welfare perspective. Understandably, this ocular infection is extremely painful. Early and aggressive treatment can help mitigate suffering and prevent vision loss in your animals.
Because this is a bacterial infection, antibiotics are the most effective treatment. Because these medications are prescription-only, work with your veterinarian to settle on a treatment regimen. This will likely include injectable antibiotics in addition to other management options such as an eye patch to help protect the eye as it heals.
Other options may include housing the affected animals inside, out of the sun, during their convalescence.
Another tool to consider incorporating in your pinkeye control kit is vaccination. There are a handful of USDA-approved pinkeye vaccines available on the market, but it is important to understand their utility. Differing genetic strains of Moraxella exist, and what strain your herd has may influence the efficacy of the vaccine. Talk to your veterinarian about whether incorporating a pinkeye vaccine into your program is appropriate for your herd.
Obviously, good fly control goes a long way to also helping control the level of pinkeye outbreak on your farm. Offering cattle plentiful shade can also help, as can reducing the amount of tall grass and weeds in the pastures, as mechanical injury to the eye through seedheads can also contribute to this bacterial infection.