Back From the Vet: Pink Eye in Goats
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Livestock ownership in summertime comes with many challenges. Notably, controlling insects can become quite difficult. Flies and other flying insects, in addition to irritating animal owners, can increase the risk of disease in animals. One of the common conditions that flies can exacerbate is pink eye or infectious keratoconjunctivitis.
In goats and sheep, pink eye can be caused primarily by infection by two different bacterial types, Chlamydia and Mycoplasma. These bacteria invade the tissue around and within the eye, causing pain and inflammation. The bacteria can invade the eye all by themselves, but external irritation to the eye can increase the risk of infection. External irritants include flies, dust, and even just stress. Adding new animals to a herd can introduce the infection, and pink eye is highly contagious and can spread quickly through a herd. Unfortunately, even previously infected animals can become infected again, making any animal susceptible.
As the name implies, goats affected with pink eye show signs of redness of the eyes. This redness can be in the conjunctiva or the cornea. The pain associated with the infection can cause squinting of the eye and discharge which can be clear to cloudy and yellow-green. There may also be swelling of the eyelids. Severe and untreated infection can lead to ulceration or scratching of the cornea (the external surface of the eye globe). This causes further pain and inflammation and can lead to severe damage to the eye and abscess formation within the eye. Goats with mild disease can have decreased vision; severe infection can result in permanent blindness.
Owners can treat pink eye in a variety of ways. The most successful treatment is topical application of antibiotic drops or ointment to the affected eyes. Oxytetracycline ointment is the most effective. Unfortunately, to be very effective, owners must apply the ointment at least three times daily.
When frequent animal handling is not possible or efficient, other options exist.
- An injection of antibiotics can be given into the conjunctiva of the eye. As this requires placing a sharp needle near delicate ocular tissue, only provide it under the direction of a veterinarian.
- Goats can also receive systemic injectable antibiotics, primarily oxytetracycline or Tylan. This treatment tends to be less effective than topical medication but still improves the condition.
- In large herd outbreaks, antibiotics can also be given in food or water, but only with a veterinary prescription.
As pink eye is highly contagious, when treating any affected animal, it is essential to wear gloves and change them between animals or to wash hands thoroughly between animals. Improper handling of animals during examination and treatment can result in further disease transmission.
Prevention of pink eye involves reducing risk factors.
Overcrowding, decreased ventilation, and poor insect control are predisposing factors to pink eye. Always ensure adequate space for animals with well-ventilated housing.
Placing fans for airflow will not only improve ventilation but can also reduce flying pests. Removing manure and providing appropriate ventilation can help reduce insects. Topical medications can also decrease insect irritation. Your herd veterinarian can recommend products to improve your insect control program.
Isolating new animals before introduction into the herd can also reduce the risk of pink eye. Keeping new animals, or those that have traveled for shows or breeding, isolated for 30 days before introduction into the herd can reduce the risk of bringing in harmful conditions such as pink eye. While there is a vaccination to help prevent pink eye infection in cattle, unfortunately, there is no such vaccine for sheep and goats.
An outbreak of pink eye in a herd can lead to loss of production. Animals are dumpy and irritated, resulting in decreased milk production and decreased weight gain. Severely affected animals can become permanently blind.
In addition to these losses, infection treatment can be time-consuming and costly. Ensuring preventative measures are in place can reduce the risk of a pink eye outbreak within a herd. If animals in your herd show signs of ocular irritation or blindness, work closely with your veterinarian to ensure that these animals get the appropriate treatment.
Note: Bacterial infection is not the only cause of eye irritation or decreased vision in goats. Closely examine animals showing signs of pink eye for foreign bodies within the eye. Material such as foxtail, cheatgrass heads, or other abrasive feed material can become lodged in the eyes, giving similar signs.
Animals may show signs of infection when affected by a condition known as entropion, which is a congenital condition; animals are born affected. Animals with entropion have eyelids that roll toward the eyeball, and this causes the eyelashes and hair around the eyes to constantly scratch the eyelids. As animals with pink eye have decreased vision, consider other conditions that result in blindness, such as lead poisoning, polioencephalomalacia, and listeria. Always perform a thorough exam of animals showing signs of blindness or ocular irritation to ensure the pursuit of appropriate treatment.
Originally published in the September/October 2022 issue of Countryside and Small Stock Journal and regularly vetted for accuracy.