Prevention can be difficult because the disease is spread by flies and vaccines usually work on only one strain
Cattle pinkeye, more scientifically known as infectious bovine keratoconjunctivitis, is an expensive illness.
It costs cattle producers thousands of dollars annually due to poor weight gains in affected animals, reduced milk production, cost of drugs and labour to treat infections and lower prices at sale time for animals with eye damage or blindness.
Stockmen generally try to prevent pinkeye outbreaks but this is often a frustrating challenge.
Rob Swackhammer of Upper Grand Veterinary Services in Guelph, Ont., has seen many cases.
“Pinkeye is a challenging problem because this disease is spread by flies and not easy to prevent. Fly control is important to try to reduce spread to other animals. Cattle with eye irritation are susceptible since this gives the bacteria access.”
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Anything that scrapes or irritates the eye surface may enable this disease to get started. When cattle graze pasture with tall, mature grasses, seed awns may cause eye irritation, as do sunlight, dust and flies.
“There are vaccines available but most of them only include one strain,” said Swackhammer. “It may not help against some of the other bacteria that might be involved but can be another tool in our toolbox and might be worth a try if pinkeye has been a big problem in certain herds.”
Autogenous vaccines created from strains of bacteria found on the affected farm are one strategy. Many people feel these are effective but they may get too much credit for preventing a problem, said Swackhammer.
In some years, pinkeye is less of a problem regardless of vaccine use. Weather and environmental conditions vary from year to year, affecting incidence.
Insecticide ear tags can help with fly control. They are more effective against horn flies, which spend more time on the animal, than against face flies that spread pinkeye.
“Some people use a mineral/salt feeder with a cloth that hangs down in front of it that spreads insecticide dust/powder on the animal’s head and neck when it reaches in to eat salt and mineral. This can help deter flies on the face,” Swackhammer said.
Some pour-on insecticides also have fly control effects.
Even with the best efforts at control, some years are worse than others for pinkeye.
“The earlier you can treat it, the better. Treatment should be administered according to the advice of your own veterinarian, since local conditions on your farm or ranch may be different than somewhere else,” he said.
Topical eye medication can be applied to show cattle or dairy animals that are handled often. However, these don’t last long and must be frequently repeated.
Injections of long-acting tetracycline can be effective. The medication is absorbed into the bloodstream and then into tears that wash over the eye.
“In severe cases, producers may put a patch over the eye as well to protect it from irritation of sunlight, dust, flies, etc. The downside of a patch, if it’s not glued on properly, is it could allow flies to get in underneath and really go to town on that eye, so that’s the risk of using a patch,” said Swackhammer.
Pinkeye is painful. The eye is sensitive and the animal holds it shut.
“Anti-inflammatory medication like meloxicam or banamine may improve quality of life for the animal and help with healing and treatment because inflammation hinders healing,” said Swackhammer.
Controlling inflammation is important. An animal in pain won’t eat well and may lose weight, making it a welfare issue as well as an economic one. Producers should not let it go untreated.
Veterinarians will sometimes inject a combination of an antibiotic and an anti-inflammatory steroid under the membrane of the inner eyelid.
“This has a local effect that lasts longer than topical medication put into the eye. You are putting this under the surface of the inner eyelid, and the hole where the needle went in allows it to ooze out slowly and cover the eye surface for a much longer time,” Swackhammer said.
The injected antibiotic may get into local blood circulation around the eye, which can accomplish in one treatment what several days of topical medication might do.
Pinkeye is generally a summer problem due to intense sunlight and more flies. However, dusty hay or foreign bodies that scratch the eye surface can cause problems in other seasons.
Watery eyes and squinting are among the initial symptoms. Early treatment can prevent damage.
Sometimes a seed or sliver gets caught under an eyelid and the inflammation can’t clear until that irritant is removed.
“If you don’t see a response from your treatment in two or three days, you need to look closer into that eye and see if something is caught under the eyelid. It may just look like pinkeye,” said Swackhammer.
“It’s probably best to check even before you treat the eye, to get a good look under the eyelids and around the eye socket to make sure there is nothing caught in there.”
Pinkeye is contagious. Once an animal has it, flies carry bacteria from that animal to others so prompt treatment is recommended.
