by A.J. Tarpoff, DVM, MS, Beef Extension Veterinarian
Pinkeye (Infectious Bovine Keratoconjunctivitis) can be a costly disease for cattle producers during the summer and early fall in Kansas. Understanding the cause, signs, treatment, and prevention of this disease can go a long way in reducing pain and discomfort for the cattle as well as help the productivity of the cattle operation.
Cause: Pinkeye is a multifactorial disease that is often initiated by direct irritation to the cornea followed by bacteria invading the lesion. Moraxella bovis has long been considered the key pathogen in pinkeye cases, however, other bacteria such as Moraxella bovoculi, Mycoplasma bovis, and Mycoplasma bovoculi have been implicated as well. Factors that can contribute to the disease are as follows:
- UV radiation from the sun
- Dust
- Grass awns (scratches on the eye from grazing tall grass)
- Face flies
- Flies feed on discharge from the eye. They can spread the bacteria rapidly from animal to animal.
- Stress
- Concurrent disease or viral infection (IBR, BVD)
These factors can cause physical irritation to the surface of the eye initiating the disease or inhibit the body’s natural defense mechanisms.
Signs: Excessive tearing, blinking, and squinting are all early signs of pinkeye. The excess tears often drain down the face collecting dirt and grime. This can be seen from a distance. As the disease progresses the eye becomes extremely red, the cornea (clear part of the eye) becomes white and cloudy. The clear cornea can form an ulcer and even rupture in severe cases. Healed lesions on the cornea will appear as a white scar, which may clear over time.
Treatment: Injectable long acting oxytetracycline antibiotics are often used for treatment of pink eye cases with good effect. There are labelled veterinary prescription options as well. It is always important to work with your local veterinarian and have a valid Veterinary Client Patient Relationship (VCPR). If pinkeye is becoming an issue on a premise, a veterinarian has the tools and expertise to help in face of an outbreak. Samples may be sent to the diagnostic lab to determine the best course of treatment.
To help with the healing process, it is recommended that a glued eye patch be applied to the affected eye. An eye patch does two things to promote healing. First, it takes away the irritant of the sun’s UV radiation and wind. Eliminating these irritants will increase cattle comfort during the healing process. Second, the patch can help decreasing the spread of the disease by physically blocking flies from feeding on the tears of the affected eye.
Prevention: Prevention starts with ensuring optimal herd health. Quality forage along with vitamin and trace mineral supplementation supports a strong immune system. The immune system can be hindered during times of stress from shipping, weaning, weather, and changes in feed. A solid vaccine program against respiratory pathogens such as IBR and BVD is also important to help strengthen the immune system. These viruses can contribute to the severity of pinkeye outbreaks.
There are many commercially available pinkeye vaccines available on the market. There are also several companies that offer autogenous vaccines as well. Inherently pinkeye vaccines have some downfalls. There are many different subtypes of the bacteria that cause pinkeye. Many of which can be isolated from just one infected animal. Although the vaccines usually have several strains, unfortunately the different strains are not cross protective. This means if a different wild strain subtype of the bacteria infects the animal, disease may still occur in a vaccinated animal. If pinkeye vaccines are used, it is important to administer these products at least 4 weeks prior to pinkeye season (some products require 2 doses) to ensure adequate response. Discuss vaccine options with your veterinarian to see if they may have a place in the herd health plan.
Other ways to help prevent the disease is to manage the environment and vectors of the disease. This can include mowing tall stands of grass and weeds in the pasture or using dust mitigation strategies. This reduces the scratching and irritation potential. Fly control is also very important. Strategies may include fly tags, pour-on products, dust bags etc. Providing simple shade structures can decrease the irritation of the sun during the middle of the day. Also isolating infected animals may decrease the spread to other animals. Using these strategies will help prevent pinkeye severity on an operation.
