Pinkeye Issues and Farmers’ Solutions
In early September, the PFI listserve exploded with questions and feedback concerning pinkeye in grazing livestock. Nearly everyone who has worked with a herd on pasture knows the shock and worry that come with the first sighting of tear-stains and yellow-marred eyes. After an initial call for input, PFI farmers quickly submitted their thoughts, findings, observations, and knowledge. Jennifer Vasquez was kind enough to organize and tabulate the responses, which are included again with some additional notes.
What causes pinkeye?
The bacterium Moraxella Bovis is the most common culprit behind pinkeye breakouts in cattle. More recent veterinary research work indicates that some other Moraxella subspecies may be working with M. bovis, however. In sheep and goats, infection is often caused by Chlamydophila pecorum or a variety of Mycoplasma subspecies.
While the bacteria are the infectious agents, it is often irritation to the eye that leads to symptoms. Abrasions from dust, pollen, or forage (particularly dry stems or seedheads) scratch the eye and allow the bacteria to invade. In the early stages, the eyes will look cloudy. Unless animals are monitored frequently, the first apparent sign may be weeping eyes and apparent blindness.
How can pinkeye be prevented?
Compouinding on the bacterial and physical threats to the eyes are other stressors and deficiencies. High sunlight exposure and shipping stress cause general strain on the cattle or their eyes, and may increase susceptibility. Some nutiritonal factors are involved, particularly deficiencies in some vitamins and minerals:
- Vitamins A, D, and E; selenium, copper, zinc, and manganese. Supplementing these as either injections or mineral feeds bolsters the immune system and may lower the risk of infection or help stave off an attack.
- Kelp offered free-choice has been associated with reduced pinkeye breakouts on some PFI farms.
- Other supplement options, including larvicide and diatomaceous earth, help reduce the fly populations themselves.
When considering injections and supplements, always remember to check for their acceptability to organic or natural regulations.
Other methods of prevention mostly aim to reduce fly populations and reduce environmental irritants are important. Some suggestions from the listserve and fly control field days are below:
- Select livestock for fly resistance and dark-pigmented eyes (animals with white or light skin around the eyes are more susceptible).
- Vaccinations are highly debated. Due to the variety of potential disease-causing bacteria, a generic pinkeye vaccine may not provide much protection. Autogenous vaccines – those created specifically for the infectious agent on a given farm or in a given region – are more likely to succeed. Communication with a local vet for the appropriate vaccines to use would increase the efficacy.
- Fly traps of any sort: see the Peake field day blog post (https://www.practicalfarmers.org/blog/2012/field-day-recap-better-grass-and-fly-control-a-dairy%E2%80%99s-path-to-profits) for some ideas and links.
- Fly sprays, especially mineral oil-based, particularly when applied to animals’ faces.
- Fly ear tags – just be sure they’re accepted within production regulations, and try and time tagging so as to kill flies before they can become resistant. A recommendation was given to alternate organophosphate and pyrethroid tags each year.
- Pasture management practices such as mowing or clipping to get rid of stalks and other irritants.
- Rotational grazing to break up the fly life cycle, prevent reinfection, and move animals away from fly “zones.”
- If feeding hay, avoid overhead hay feeders and allow enough bunk space so that animal-to-animal contact is minimized.
How can pinkeye be treated?
Direct treatments to the eyes are employed against established infections. These are more feasible for dairies, as it requires cows to be restrained for spraying. In severe cases, the affected eye should be sewn shut (with dissolving thread) or covered with a patch. Some recommendations from PFI producers are below:
- Hypochlorous acid at 0.009%.
- Hydrogen peroxide
- Boric acid at 1 tsp per pint of water.
- Colloidal silver.
- Antibiotic shots: ampicillin, penicillin, gentamicin, or kanamycin (into the subconjunctiva); oxytetracycline (into the cornea); sulfonamids, florfenicol, or tilmicosin (injected systemically).
- Antibiotics applied to the eye: triple antibiotic, gentamicin, or oxytet/polymyxin B; topical tetracycline in sheep and goats.
- In severe cases, the eye may be sewn shut (either permanently, if sight cannot be saved or in case of rupture; or with dissolving thread) or patched. Patching the eye prevents further irtritation and also reduces the chance of disease transfer to other cattle.
Additional information from the Merck Veterinary Manual: http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/30500.htm