By Dan Goehl, DVM
Got an animal health question?
The onset of summer and fly season brings thoughts of pinkeye. This disease is not only a nuisance, but can also be economically detrimental. Adding to this is the fact that it is very hard to come up with a single strategy that will prevent it from being a problem.
How can it be prevented? We can use vaccines, vitamins and minerals, antibiotics, sodium iodine, management practices to reduce vectors and irritation to the eye, and numerous other proven and unproven methods.
Which of these is successful, you ask? All of them or none of them. It depends somewhat on how you classify pinkeye. It is generally accepted that any animal with a watery, cloudy eye is described as having “pinkeye.” In actuality there are several conditions that can cause this to happen.
The most commonly recognized infectious agent to cause pinkeye is Moraxella bovis. In recent years other bacteria in this family have also been incriminated near the top of the list. Other diseases that can cause similar signs are IBR virus, Mycoplasma and vitamin deficiencies. Moraxella offers a unique challenge because it has dozens of different strains. This makes it very difficult to make a vaccine that will protect against all of the variations. What is causing a severe outbreak on one farm may be a different strain from what the operation across the road is suffering from.
Moraxella is spread from animal to animal in a variety of ways. The most common is that of the face fly. The face fly feeds on eye secretions and irritates the surface of the eye in the process. Eliminating face fly problems removes one of the main mechanisms of transfer for the disease-causing organisms. The face fly provides some unique challenges in trying to control, primarily because it spends a very small percent of its lifetime on the cow.
Avoiding irritated eyes is key to controlling the pinkeye syndrome for two main reasons: tearing attracts flies and irritated eyes are more susceptible to disease. The first line of defense for the eye is the cornea or outer surface. If this is disrupted, it is easier for bacteria to invade and overcome the immune system.
A variety of sources generate inflamed eyes. Minimizing environmental irritants including grass seed heads is an important step to prevent problems. Clipping fescue and orchardgrass pastures after they mature allows the animals to graze without constantly getting grass seed in their eye. It also helps to control the effects of endophyte toxicity associated with most fescue pasture. Another successful strategy to manage seed heads is to utilize intensive grazing to keep the forage in a vegetative state.
Animal type and age also influence susceptibility to pinkeye. Cattle with no pigment in the skin around the eyes (white-faced) may be more susceptible due to reflection of the UV rays from the sun. Older calves tend to have fewer problems with pinkeye, and this is an advantage for fall calving herds. The calves are generally born after the heart of pinkeye season and are older by the time it comes around again.
Presumptive diagnosis of pinkeye can usually be made from observation. The earliest signs of a watering eye progress to a corneal ulcer in the center of the eye, and then to a cloudy colored eye. Severe cases result in blindness and at times a ruptured eye.
When these signs are observed, various treatments can be implemented. Eye damage can occur very rapidly and the sooner treatment is initiated, the better the prognosis for long-term recovery. Generally all treatment plans consist of some type of antibiotic treatment. This can be a systemic, i.e., injectable, antibiotic, a topical spray or ointment. Depending on the situation, it may also be necessary to suture the eye closed or use a patch to eliminate irritants from the eye.
Prevention of pinkeye is the objective, as once it reaches the stages of needing treatment, economic loss has been suffered. As mentioned before, there are several theories on how to prevent pinkeye and most of them have some merit. It is best to talk with your animal health care professional to come up with a strategy that is specific to your area and your operation.
If you have a successful pinkeye prevention program going, then I would not change it -- but be cautious about bragging to the neighbor!
Dan Goehl, DVM, and his wife own and operate Canton Veterinary Clinic in Canton, Mo., where Dan works primarily with stocker and cow-calf beef operations. Dan is also partner in Professional Beef Services, LLC, which offers herd consultation and helps in data management and marketing of beef cattle.
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