It is possible that it can hit year-round but for the most part, it is a pretty seasonal affliction. This disease usually increases in spring, peaks during summer, and then will decrease during the fall. This is because, like most bacteria, it prefers warmer weather to cold.
It can be very labor-intensive to treat and as I mentioned a couple of lines ago it can spread quickly if not taken care of in time. No matter the severity it is best that you quarantine all of the cattle that have it so you can prevent it from getting to the others.
Causes of pinkeye in cattle
The primary cause of pinkeye is a bacteria called Moraxella Bovis. What happens is if there is any damage to an eye this little guy will get into the cow’s eye causing all kinds of problems.
Things like face flies, dust, and tall grasses can cause eye irritations which will invite the bacteria to set up shop. Face flies feed off of the secretions then when they go to other cattle they will spread the bacteria to them. This is a reason why it is highly recommended that you take steps to keep flies in your pasture under control.
Some studies have also found that certain breeds of cattle are more likely to get pinkeye than others. Breeds like Herefords and Charolais are a couple of the breeds that are more likely to get it. The reason for this is because of the lack of pigmentation around their eyes as well as their increased sensitivity to sunlight.
Improper nutrition can also play a factor in the outcome of this disease. Deficiencies in things like Vitamin A, Copper, and Selenium can make it more severe.
Clinical Signs
When it comes to pinkeye in cattle there are generally 3 stages in the symptoms:
Stage 1
- During this stage, cattle will have excessive tearing
- Will also have an increased sensitivity to sunlight
- Due to the irritation and sensitivity, the cattle will tend to blink more than usual
- The cornea will develop a slightly cloudy grey appearance due to inflammation
- Can progress to a small ulcer which will appear as a small white spot
Stage 2
- Signs from Stage 1 will continue but the ulcer will spread across the cornea
- The eye will become more cloudy in color
- Some of the dark colors of the iris can still be seen
- Blood vessels on the outside portion will begin to grow to make it appear pink (this is what gives the disease its name)
Stage 3
- The ulcer covers most of the cornea
- Inflammation spreads to the inner part of the eye
- The inside of the eye will fill with a pus-like substance called fibrin making the eye appear yellow
Prevention of pinkeye
Because of the random nature of outbreaks and the many factors that contribute to the disease, there have been many myths regarding pinkeye prevention. This has led to many different things being used, some have been successful while others…. not so much.
Proper management that reduces the risk factors of cattle getting pinkeye is the best step to keep this disease at bay. When the disease doesn’t show up as much the concentration of the bacteria will be reduced thus lowering the chance of an outbreak.
Fly control on your operation is a very good first step in getting this disease under control. The problem with this is that face flies only live on the animal for a short time making it difficult to do this. Taking care of the larval and egg stages as well as the adult stages is your most effective strategy. I go over the steps that you can take in controlling fly populations in a previous article “How do you control flies on cattle?”.
Keeping your pastures grazed at the correct height is another strategy that you can use. This will prevent the grasses from reaching seed-head development which will reduce the chance of eye irritation in your cattle. If you are not able to keep the pasture grazed to the right height then mowing will work instead.
Treatment of pinkeye
Treating cattle with pinkeye early enough is important in preventing spread. Depending on what stage the signs are at will determine what treatment you will need to do.
Stage 1
Giving the infected cattle a treatment from long-acting oxytetracycline such as Bio-mycin 200 or LA200 will be very effective at this stage. The recommended dose that you should give is 4.5cc per 100lbs of body weight subcutaneously or under the fold of the skin. A second dose given within 48 to 72 hours may increase the percentage that will respond to treatment.
It is also recommended that you put a patch over the infected eye. This will prevent other irritants from getting in there making the problem worse. It will also help with the cow’s increased sensitivity to sunlight.
Commercially available patches will work well for covering the eye. If you are not wanting to do that 5″x6″ blue jean patches cut to size with glue on three sides leaving the bottom open will also work. To ensure that the patch stays on use cattle backtag cement to glue it in place. Just make sure not to get any glue in the eye.
Stage 2
Treatment with tetracycline at the same dose as stage 1 will do the trick here. A bulbar injection with either penicillin or dexamethasone in the white portion of the eye will work just as well.
Stage 3
An oxytetracycline injection and bulbar conjunctival injection will be necessary at this stage. Along with this, you will need to place an eyepatch for sure. It will also be necessary to suture the third eyelid of the cow over the eye and close it.
Suturing the third eyelid over the eye will prevent any debris or other irritants from getting in. It will also make the eye more comfortable reducing excessive tearing and possibly shedding bacteria.
Another advantage of suturing the eyelid shut is that it will support a fragile cornea helping to prevent corneal rupture.
Disclaimer: Any suturing should be done by a veterinarian or someone who has been adequately trained to do that so as not to run the risk of damaging the cow’s eye.
Michigan State has a publication that goes into more detail about cattle pinkeye if you would like to read more about it.