8 March 2023

5 minute read

By: Penn State University

North America

Both forms of pinkeye are of bacterial origin. Last year proved to be a challenge dealing with pinkeye in Pennsylvania cattle herds. It's extremely important to be vigilant in checking cattle and more specifically the eyes of cattle for early signs or symptoms of pinkeye. This summer is promising to be even more difficult than last with the prevalence of this newer strain of pinkeye in the state.

Bovoculi has previously been detected in the eyes of healthy calves when conducting cultures during a research study in 2002 at The Meat Animal Research Center in Nebraska. Many times, it is been suggested lighter colored cattle are more susceptible to the challenges of pinkeye. 

Bovoculi doesn't seem to have a color preference or be color specific. It appears to be equally challenging for all breeds. As with all forms of pinkeye, fly control is extremely helpful to reduce the incidence in a herd. Particularly face flies are an extremely efficient vector for moving pinkeye from animal to animal. Additionally, make sure to include the calves in the herd in the fly control program, they can also be a source of the bacteria responsible for pinkeye in the cow herd. 

Bovoculi is an extremely aggressive form of pinkeye. Once it gets a start in the cow herd it appears to be very aggressive and moves through the herd at a higher rate of speed than the common pinkeye you are probably more familiar with. It also seems to be less responsive to traditional treatments. With outbreaks in individual animals lasting weeks at a time.

Any potential eye irritants may increase the prevalence of pinkeye. For example: tall dry grass seed heads have a tendency to become dislodged from the plant and end up in the eyes of cattle especially calves as they begin to graze. Any and all eye irritant will cause an eye to tear. The irritation of dust, plant pollen or weed seeds will promote tearing from the eyes. As a result, bacteria will also be shed.

Eye irritation can be caused by any plants that have awns. The awns can cause significant irritation to the eye. This family of plants or other weed seeds with awns that can stick in the eye will eventually lodge in the eye and can cause significant damage, irritation, and watering of the eye. It's the bacteria in the tears of a few "carrier animals" in the herd that are the initial source for a pinkeye outbreak. The carrier animals then spread the organism by contact and/or via face flies to the rest of the herd and susceptible animals may become infected and develop clinical pinkeye. Face flies that are attracted to this tearing can easily spread the pinkeye organisms between animals.

Cattle being examined for pinkeye should also be checked for the presence of foreign plant material in the eye like awns. If they are discovered in an eye, they must be removed to allow the eye to begin to heal. With uncomplicated pinkeye, the damage usually begins in the center of the eye and spreads outward. With an awn or other foreign body, the damage will be "off-center". The examination of the eye by individuals also creates another opportunity to spread of the disease between animals. 

Adherence to strict Biosecurity between animals will help control the spread of the disease. Consider wearing examination gloves when dealing with pinkeye, be sure to change your gloves between animals. The routine use of a disinfectant for any equipment used on animals with pinkeye is necessary. Nolvasan (chlorhexidine; Fort Dodge) is an excellent choice because it is not irritating to eye tissues and works well as a disinfectant. Your veterinarian can also suggest other disinfectants that will accomplish this goal.

Consult your veterinarian about a vaccination program

Your veterinarian may be the most important part of your prevention plan. Get your veterinarian's advice about prevention before the outbreak, or, if you had problems last year, seek their advice ahead of time. Topics to be covered should include (1) fly control; (2) vaccines; (3) disinfectants; (4) tools and supplies to have on hand for prevention and treatment; and (5) treatment protocols and any necessary prescriptions.

Vaccines can be effective in preventing pinkeye and there are a relatively large number of vaccines available—which usually means no single vaccine works perfectly. It is usually recommended for producers to start with one of the commercial vaccines suggested by your veterinarian. He or she will have knowledge about which vaccines are currently working well in your area and more importantly, which are not working. Remember most vaccines for pinkeye require 2 doses generally 2 to 3 weeks apart to be effective. It usually takes a month or more for immunity or protection to develop. Thus, the most effective vaccination programs begin well before the start of pinkeye season. Most important be sure to vaccinate for both Bovis and Bovoculi each year. If you select only one you most likely will have trouble with the other form.

The pinkeye agent is a bacterium and therefore, antibiotics are indicated for treatment. The question always is, "Which antibiotic works, what dose and what route of administration?" for the best treatments and what works in your area consult with your herd veterinarian. Additionally, there are some liquids and spray-type products still available for pinkeye treatment. Just remember these products only stay in the eye for about 7 minutes before the tears wash it out and therefore, are much less effective than any antibiotics administered directly to the animal. 

Consider reviewing your current mineral program. If your cattle are copper deficient or selenium deficient, the number of pinkeye cases will be greater and the severity will be worse. Be sure your mineral program is working, as this is important in the animal's immune response to this bacterial pathogen.