Pinkeye: A Variable Disease Requires Variable Solutions.

 By Jaclyn Krymowski.

 Pinkeye is an unsightly and damaging disease, one many producers are all too familiar with, formally known as Infectious Bovine Keratoconjunctivitis or IBK. Not only does it cause undue discomfort and, sometimes, even permanent lifelong damage, pinkeye can also be very costly in terms of expenses and losses.

According to the Virginia Cooperative Extension, pinkeye costs the cattle business an estimated $150 million loss each year. Due to the multi-factorial nature of the disease, the estimate is variable but accounts for treatment, decreased performance and possible loss of value at the sale barn. It can also be an additional cost to prevent the disease via fly and pasture management.

Even when producers invest in good prevention practices, it is far from surefire. Pinkeye is tough to work with it due to being highly contagious and having a somewhat random behavior when it comes to appearing and disappearing. Understanding treatment – and how to reduce the spread – are important things every cattleman should know.

Causes and other Factors
The most common pinkeye pathogen is the hardy, gram-negative bacteria Moraxella bovis. However, there are other pathogens, such as Infectious Bovine Rhinotracheitis (IBR), capable of causing extremely similar conditions. In case of outbreaks and mass treatment, culturing may be wise.

Pinkeye often flares in the summer months when the flies are at their peak and the grass is tall. Face flies in particular are one of the most important vectors for the carrying and proliferation of the disease. It can, however, strike any time of the year without warning.

There are some factors that make individuals more susceptible. Animals with white eyelids are at higher risk than those with pigmentation. Eyelids without pigmentation have greater photosensitivity and a weaker immunity in that area.

External factors include exposure to sunlight, dust and other biological particles nutritional deficits and other infections can also predispose certain individual to pinkeye or increased severity of the disease.

Symptoms are usually tell-tale: excessive weeping, avoiding light, keeping the eye closed follow up inflammation and whiteness in the cornea. It takes several days for the infection to reach its worst, but if treated promptly a full recovery is likely.

Permanent damage is usually the result of not being treated, treated too late or exposed to ongoing issues in the healing process such as cornea damage and sunlight exposure.

Prevention
While it can strike any breed at any time in any region, there are several options for ranchers to safeguard their herds.

Commercial vaccines exist, but there is ongoing discussion as to how effective they actually are. Many ranchers have yielded mixed results, and the randomness of the disease makes the value questionable. In some cases, a custom vaccine with a sample cultured from the herd might be the best option in serious circumstances. Before making the leap to such an investment, it is beneficial to discuss the situation with your veterinarian to develop a program.

There is room for potential complications when vaccinating infected animals for IBR. According to a Virginia Tech Extension article, this vaccine can damage the delicate cornea cells. This makes it easier for M. bovis to invade and proliferate the disease by giving it a better surface to cling to and reproduce.

In one bulletin, Dr. Richard Randle, retired University of Nebraska-Lincoln Extension Veterinarian, says under that experimental conditions the absence of flies makes transmission of pinkeye extremely reduced.

He also notes face flies can carry the M. bovis bacteria up to three days after picking it up from one infected individual. From there, it has the potential of spreading the disease to every other animal is makes ocular contact with.

Some of the most effective things that can be done include good hygiene and having a strong fly management program. These efforts must be multi-pronged as no single solution can work for one single farm. Larvicides, dust bags, treated ear tags and good manure management are all components that can reduce overall fly populations.

Pasture management also factors in here. Very tall, abrasive forages can irritate the eye with small, subtle cuts and inflammation which encourages infection and attracts flies. Likewise, separating infected animals from the rest of the herd when possible can also greatly reduce the risk of spread. At the least, offer sufficient bunk space and room to discourage animals from making physical eye contact.

Treatment
To minimize losses, pinkeye should be treated as soon as possible after diagnosis. According to Michigan State University Extension, a true outbreak of the disease occurs when there is an infection rate from five to ten percent. When an outbreak is evident, blanket treatment of the herd may be a considerable option.

Treatment and administration vary widely with different degrees of effectiveness. For severe and widespread infections, direct ocular injection can be the most potent. Because this can cause significant and permanent damage, it should be done by a veterinarian or someone who has been specifically trained.

Exposure to sunlight can hinder the healing process as evidence suggests ultraviolet rays promote further damage to infected eyes. Eyepatches are the best solution to allow for treatment post-healing in pasture settings. In extreme cases, a vet may need to suture the eyelid shut for optimal protection.

Pasture management should always be taken into consideration when treating to prevent eyeballs from ongoing scratching and further damages.

According to one study, pinkeye is the second most common issue cattlemen face. With so much variance from year to year, an effective response is one that is flexible and diligent.