Beef Cattle Mythbuster

Pinkeye

Dr. Don Llewellyn Livestock Extension Specialist
Director, WSU Lincoln County Extension, Davenport, WA

Sometimes it takes some thinking to figure out what to write for an article. I try to make the content relevant and applicable to real-world cattle production. Finally, I asked myself, as summer approaches what are the real issues that I faced as a cattleman?

One of the summer issues that a lot of us have experienced is pinkeye. It terms of a cattle disease; I think we all can agree that it be both an economic problem, a cattle well-being issue, and a nuisance as well.

In veterinary medical terminology, pinkeye is called infectious bovine keratoconjuctivitis (IBK). It is characterized by blepharospasms (involuntary movements of the eyelids), inflammation of the membrane of the eyelid and eyeball (conjunctivitis), flow of tears (lacrimation), and changes in the opacity (transparency or translucence) of the cornea. A key clinical sign is ulceration of the cornea.

Infectious IBK can be caused by a host of organisms requiring testing to determine the specific organism involved in an infection. Historically, antibiotic treatment has been indicated for IBK infections. Both topical and injectable antibiotics have been used. There are also some vaccines available for IBK, but there has been significant discussion as to their efficacy.

Currently vaccines are available for Moraxella bovis and Moraxella bovoculi (both are bacteria involved in pinkeye). However, a laundry list of possible causative agents has been suggested. Even Infectious Bovine Rhinotracheitis virus (IBRV) has been proposed. All ages of cattle are at risk, but young cattle being affected is very common.

Risk factors:

Flies
Dust
Trace mineral deficiencies such as selenium and copper
Mechanical irritation from grasses, like cheatgrass
Ultraviolet light

In addition to the clinical signs described above, cattle with severe IBK may exhibit opaqueness of the cornea within two or three days. The cornea can become deeply ulcerated with risk of rupture. Cattle that do recover may have varying degrees of blindness due to scarring. Prompt treatment can minimize scarring, but cattle summering in remote locations may not be seen often enough to head off severe cases of IBK. In my experience, cattle in remote locations resulted in a heightened risk of blindness in one or both eyes primarily in calves, but also affects cows as well. For photos of the progression of IBK infection, see:

https://www.merckvetmanual.com/eye-diseases-and-disorders/infectious- keratoconjunctivitis/infectious-keratoconjunctivitis-in-cattle-and-small- ruminants?query=pinkeye%20cattle#Clinical-Findings_v3270173

Treatment:

Your veterinarian can assist you in selection of appropriate antimicrobials to treat the various bacterial infections. Remember, only a veterinarian can prescribe extra-label use of antimicrobial products.
Topical sprays and ointments have been used successfully, but typically must be applied daily and that might not be practical in cattle that are in remote
Remember to follow label instructions for antimicrobial withdrawal times when using the products in animals that will be used for meat or milk.
Temporary eye patch can assist in protecting the eye and facilitating healing (Wow! I thought only oldsters like me still used eye patches along with antibiotics to treat pinkeye infections; it’s right there in the Merck Veterinary Manual!). The eye patch protects from light, flies, and reduces the chance of spread of bacteria (and they work!!!).

Prevention:

A main avenue of preventing IBK is controlling the risk factors:
Control face flies that act as a vector for IBK infections with dust bags or insecticide ear tags (when fly tags were introduced for commercial cattle use in the early 1980s, they were a revolution and highly effective in controlling flies; however now the use of fly tags require rotation of products to remain effective and prevent fostering insecticide resistant strains of flies).
Pasture rotation to keep animals away from dry grasses and the awns that can cause mechanical irritation (not always practical if all pastures or rangeland is dry in an area).
Trace mineral supplementation of selenium and copper (if needed).
Isolate infected animals if
Clean and disinfect equipment thoroughly that is used in treatment of infected
Keep a close watch on cattle that have been comingled at fairs, shows, and
Discuss the use of pinkeye vaccines with your veterinarian to determine if they would be cost-effective for your operation and have a reasonable chance to be effective. If vaccines are used, it is important to administer the vaccine at least four weeks before exposure so the animals have time to build resistance to the causative organisms of IBK.

Conclusions:

Pinkeye is both a serious malady and a nuisance for cattle producers. It is important to note that pinkeye causes significant pain and suffering to our livestock. As stewards of our animals, utilizing practical tools to minimize pain and suffering is our responsibility. Managing the risk factors along with the tools and available technologies can help keep our cattle healthy.

This article adapted from the Merck Veterinary Manual (see link) and for more in-depth reading on the topic of IBK, see:

https://www.merckvetmanual.com/eye-diseases-and- disorders/infectious-keratoconjunctivitis/infectious-keratoconjunctivitis-in-cattle-and-small- ruminants?query=pinkeye%20cattle

By the way, if you all have any questions or ideas that can result in an article, please let me know.

Summer is on the way, and we hope the rain will be on the way too! Please let me know if I can assist you with your cattle, forages, and feed. Don Llewellyn , 509-725-4171, don.llewellyn@wsu.edu