Hate dealing with pinkeye? Isn’t it a summer issue? So why do outbreaks occur at unusual times of the year?
Despite years of research and focus on prevention strategies, pinkeye remains a frustrating disease. The impacts of the condition to infected cattle and the beef industry are significant. With potential for multiple pathogens to be involved and a variety of environmental risk factors, identifying effective solutions is a challenge.
Over time, multiple strategies have been proposed, and while no single idea has adequately addressed the problem, using a combination of techniques to reduce the risk of disease has surfaced as the best approach. These measures include practicing good pasture management, fly control, trace mineral supplementation and vaccination.
The problem
Pinkeye or infectious bovine keratoconjunctivitis (IBK) is an infectious disease that damages the eye and leads to inflammation of the eyelids in cattle. Historically, Moraxella bovis has received the most attention as the bacteria causing pinkeye. While it is considered a primary pathogen, other bacteria like Moraxella bovoculi and Mycoplasma bovoculi may be involved. Mixed infections are common. Strain variation among each type of bacteria adds to the microbial diversity.
Cattle serve as the carriers for these organisms. With face flies acting as vectors and spreading pathogens around, the summer grazing season is the highest risk period, although outbreaks occur in early fall as well. Direct contact between animals as they are commingled in pens can account for spreading the organisms in late fall and winter.
Exposure to sunlight, wind, dust and plant material may injure the eye. Clinical signs are seen when the bacteria combine with a damaged eye surface. Younger animals tend to be more commonly affected, but adult cattle can develop the disease. While all breeds are at risk, genetics may influence susceptibility.
What to do about pinkeye
With weather playing a significant role in pinkeye, it may seem daunting to address. Focusing on the effects of heat and humidity to plant growth and fly populations, offers some opportunity. The likelihood of trauma to the eyes can be reduced by mowing taller grasses and clearing brush where the terrain allows. Careful grazing management will also maintain forage at an appropriate height.
Combating face flies is similarly difficult because some fly control options are only suitable for certain fly types. Frequent application of insecticides will have the greatest impact for pinkeye, although this may be impractical in some circumstances given the number of animals or the grazing environment. Strategic placement of rubs, oilers and dusters in well-trafficked areas is useful. In areas heavily affected by the disease, there may be a benefit to periodically replacing the cloth coverings on these devices to reduce the possibility of contaminated materials spreading the organisms to other cattle when they contact it.
Utilizing cattle rubs in conjunction with mineral access is even more beneficial. Drawing cattle to the rub as well as to the supplement availability increases the frequency of insecticide application and improves the uptake of important nutrients. Trace minerals such as zinc, copper and selenium have a role in immune function. When intake of these elements is optimized, adequate body stores are maintained, which the animals’ natural defense mechanisms use to fight infection. The regional differences and variation of nutritional content within feedstuffs add some complexity to ensuring that needs are met, especially for cattle that spend a portion of their lives living in one geography and then move to another, even if it is only temporary. Working with a nutritionist will help ensure that supplementation is appropriate.
Vaccination is another component to include in a management system aimed at reducing the incidence of pinkeye. Helping the immune system better recognize pathogens when they invade the corneal surface of the eye is essential in stopping the progression to a more severe lesion. Beyond simply reducing the likelihood of pinkeye, vaccination may also help reduce the severity and duration of disease. There are commercial and autogenous vaccines available. Due to limited cross-protection between the different bacteria and strains of each organism, the best vaccine option is selected based on matching a product to the specific microorganisms causing the problem. Commercial vaccines only tend to include one type of organism with a limited number of strains, while autogenous vaccines can be custom made to include what is found in an infected herd.
Utilizing a veterinarian, collecting samples and submitting to a diagnostic laboratory will provide valuable insight into the dynamics of the disease process. When outbreaks occur, culture and sensitivity testing can be used to select the most appropriate antibiotic therapy. Some laboratories offer polymerase chain reaction (PCR) testing and genetic sequencing that sort out which bacteria and strains are present. Once this diagnostic data is obtained, it can be combined with the expertise of a veterinarian to find workable solutions.
A veterinarian is necessary in developing the appropriate vaccination schedule for each herd. Understanding the bovine immune system will allow him or her to advise on timing of vaccination. Knowing when to start vaccinating is just as important as knowing when to booster. Antibodies decay over time, and determining the appropriate interval between vaccinations will help minimize break-through infections. There is limited data available but some information to suggest vaccinating once a year for pinkeye is inadequate. Given the possibility of waning protection and the potential for spread of the bacteria through direct contact during commingling cattle in the fall, it may be advantageous to vaccinate prior to this risk period in addition to giving vaccines at spring turnout.
Management plan
Like any disease process, having a strategy provides a roadmap for dealing with the problem. Finding the right tools that contribute to successful outcomes is the goal. Pinkeye requires a multifaceted approach.
- Pasture management: Maintain through grazing practices and mowing tall grass and brush.
- Fly control: Focus on insecticides that specifically address face flies.
- Trace mineral supplementation: Provide access to quality micronutrients 365 days a year.
- Vaccination: Administer products ahead of the risk period for disease that offer protection to the organisms and strains that are specific to the herd.
A concerted approach with assistance from nutritionists and veterinarians will greatly enhance any plan. Making sure that all steps are implemented fully is key to reducing the impact of pinkeye, as well as the frustration that goes with it.
