Reading Time: 4 minutes When it comes to herd health, keeping a watchful eye can prevent common diseases such as listeriosis, polio, and chlamydia from causing blindness in goats. Prioritize prevention and be on the lookout for the telltale signs of these four diseases; the faster that affected goats receive treatment, the better their prognosis.
A common bacteria, Listeria monocytogenes, can cause infectious disease. Listeria bacteria thrive in cooler climates. It lives in grass, soil, unfermented silage, rotting hay, and animal feces; it also transmits through milk, urine, and nasal/eye secretions of infected animals. The organism can cause encephalitis or swelling in the brain. It travels along the trigeminal nerve to the brain stem, where it causes clinical signs such as drooping ear, collapsed nostril, and flaccid tongue that affect one side of the face; fever, loss of appetite, depression, and blindness are also common. Listeriosis in goats progresses quickly and can cause blindness, blood poisoning, abortion, and death in as little as 24 hours after symptoms appear.
[optin-monster-shortcode Researchers at North Carolina State University note that the fast-spreading disease often affects up to 20% of goats in a herd. Separate infected goats from the others. Listeriosis is most common in goats under three years of age and rare in older goats. To reduce the risk of developing listeriosis in your herd, pay special attention to feeding. Ensure that all silage was properly fermented and discontinue using current feed if there is a listeriosis outbreak, advises Grace VanHoy, DVM, MS, DACVIM-LA, veterinarian and assistant professor in the College of Veterinary Medicine at The Ohio State University. Listeriosis is a serious disease, and immediate treatment is essential. “In some cases, aggressive antibiotic therapy may be successful, especially in mild cases,” says Kathryn Wotman, DVM, Dipl. ACVIM, assistant professor at Colorado State University College of Veterinary Medicine and Biomedical Sciences. “Mortality is high in advanced cases of listeria.”
Polioencephalomalacia, or PEM, is a nutritional disorder that can cause sudden blindness. It often results from deficient vitamin B1 (thiamine) in the diet. “Goats and other ruminants rely exclusively on the bacteria in their rumen to make vitamin B1,” explains Grace VanHoy. “If any disturbance in the bacterial population happens, like if the rumen becomes acidic from rumen acidosis or grain overload, those bacteria die, and goats become thiamine-deficient, which is the number one cause of polio.” The brain depends on thiamine to metabolize glucose, which is an essential energy source for the brain. With too little of the vitamin, VanHoy notes that the brain experiences an energy deficit similar to hypoglycemia that affects vision. In addition to sudden vision loss, polio, also known as cerebrocortical necrosis or CCN, can cause other abnormal behaviors such as staring into space and loss of appetite; symptoms can progress quickly, causing seizures and death. Preventing grain overload is one simple way to reduce the risk of polio in your goats. A diet that includes healthy amounts of forage encourages activity in the rumen, which stimulates thiamine for goats. VanHoy notes that CORID, the medication used to treat coccidiosis, can also cause thiamine deficiencies. The drug has a molecule that competes with thiamine and can lead to polio. Give thiamine injections alongside CORID to avoid issues. Bottle-fed kids are also at risk of developing polio. “Babies don’t have working rumens that produce thiamine…[and] a lot of milk replacers don’t have vitamin B1 in them,” VanHoy explains. If you have to bottle-raise a kid, she suggests choosing a milk replacer with added thiamine or offering thiamine pastes or gels as a supplement, adding, “The sooner you can transition them to solids, the better, because those rumen microbes will start ruminating and take over the production of thiamine.” Goats that develop polio need immediate medical attention. Injectable thiamine can reverse the symptoms. It might take a few weeks to restore vision, but, VanHoy adds, most goats do regain their sight.
