by Robert Van Saun, DVM, MS, PhD Department of Veterinary Science Pennsylvania State University
Clinical Signs. Polioencephalomalacia (PEM) is a disease of ruminant animals characterized by derangement of the central nervous system due to necrosis of the cerebral cortex of the brain.
Young animals on high grain diets are affected more often. Older animals and pastured animals may be occasionally involved. The onset is often sudden with blindness and disorientation. The head may be elevated. Excitement may be seen but is usually replaced with dullness. The animal may go down on its side with its head thrown back. The legs may be rigidly extended. Convulsions may occur. If untreated, death usually occurs within a few days. Appetite is lost and the animal does not drink. Temperature and respiratory rate are usually normal, but heart rate may be depressed.
Cause. Specific pathogenesis of this disease is not understood. Thiamine is an essential B-vitamin needed for many metabolic functions of the body. In a normal feeding situation, rumen microbes generate sufficient thiamine to meet animal needs. In PEM, thiaminase, an enzyme that destroys thiamine, is thought to be produced by certain starch fermenting bacteria within the rumen and thiamine deficiency develops. A thiamine - analogue is also produced within the rumen, which may replace thiamine in important metabolic reactions in the brain. Selected necrosis of the brain then occurs, resulting in the clinical signs.
Another nutritional situation, excess sulfur intake from either feed, water or both can produce clinical signs identical to thiamine-dependent PEM.
Treatment. Administration of large doses of thiamine intravenously, intramuscularly or both methods early in the disease will usually produce a dramatic improvement within a few hours. In the later stages of the disease, the brain necrosis may be too severe for the animal to recover.
Prevention. Gradual adaptation of animals to initial grain feeding. Until further elucidation of the cause and development of the disease, little can be done to economically prevent the disease. If a case of PEM is diagnosed in a group of animals, it is advisable to inject the remaining animals with thiamine to prevent further cases.
Additional information from long time goat owner at Onion Creek Ranch:
Symptoms of Polioencephalomalacia can be any combination of or all of the following: excitability, "stargazing" (nystagmus - involuntary eye movement), uncoordinated staggering and/or weaving (ataxia), circling, diarrhea, muscle tremors, and blindness. Initial symptoms can look like Enterotoxemia (overeating disease) because the rumen's flora is compromised. As the disease progresses, convulsions and high fever occur, and if untreated, the goat usually dies within 24-72 hours. Diagnosis is available via laboratory tests, but the goat will be dead before you get test results back.
Thiamine (Vitamin B1) injections are critical and, if the problem is Goat Polio, can result in rapid improvement if begun early. Thiamine, like all B vitamins, is water soluble, so the goat eliminates daily what it doesn't utilize in the rumen, making it difficult to overdose thiamine. A sick goat's rumen doesn't produce B vitamins.
Since symptoms of Goat Polio can easily look like Listeriosis, I use procaine penicillin (300,000 International Units) in addition to thiamine. Better to cover both possible illnesses with appropriate treatments when symptoms are so similar than risk the goat's dying. Important: I continue procaine penicillin and thiamine treatment until 24 hours after the last symptom has disappeared to avoid a relapse.
Early diagnosis and treatment are critical and complete recovery is possible. Try to avoid this disease by decreasing high grain intake, increasing quality roughage, avoiding moldy hay and grain, and not using feed that is susceptible to mold (molasses-based/textured feeds). Goat Polio is almost always caused by improper feeding.
HYDRATION AND NUTRITION: You must keep the sick goat hydrated and fed. With Listeriosis and Goat Polio, the goat is usually off feed and water. This means that you must stomach tube nutrients (electrolytes, protein) into the goat. A 100 pound goat needs one gallon of fluids daily. That is 3,840 cc's. You cannot syringe 3,840 cc's of fluids daily into a goat without stressing both the goat and yourself. Medications won't help a goat if it dies of dehydration or starvation. Unless the goat is able to eat and drink on its own, supportive care (stomach tubing electrolytes mixed with a protein source into the goat) is necessary until the goat is stabilized. For protein, I put eight (8) ounces of mixed goat milk replacer in every half gallon of electrolytes and tube feed a weight-appropriate amount divided into three or four tube feedings per day. For an adult goat, I will start tubing with no more than 16 ounces, but this must be adjusted based upon breed and age. See articles on Stomach Tubing Goats on the Articles page at www.tennesseemeatgoats.com. If you've caught the disease and begun treatment early, the goat may be able to eat and drink on its own.. Don't offer grain to a sick goat but instead provide easy-to-digest forage plants (weeds & leaves) and grass hay. Build a Sick Pen and house goats under treatment there.
Dosage and treatment with procaine penicillin 300 I.U.: TREATMENT involves administration of double the normal dosage of procaine penicillin (300,000 International Units) every six hours on a 24-hour cycle. Ten cc's per 100 lbs bodyweight of procaine penicillin is needed to cross the blood- brain barrier to maintain sufficiently high levels of penicillin in the blood stream to kill the bacteria. I give procaine penicillin SQ over the ribs with an 18 gauge needle and I don't give more than 6 cc per injection site. I also give Vitamin B 1 (Thiamine) injections, dosing at 4 cc per 100 pounds liveweight for 100 mg/ml thiamine given IM or SQ every 6 hours. The only injectable over-the-counter product with required 100 mg/ml of thiamine is Fortified Vitamin B Complex. Prescription thiamine (Vitamin B1) is available only from a vet. Injections get the medications into the blood stream faster, and quick treatment is critical with this disease. Thiamine is an appropriate addition to treatment of any sick goat. It is critical to keep to this 24-hour cycle of medicating the goat.
Very Important: Continue procaine penicillin and thiamine injections for 24 hours AFTER the last symptom has disappeared to avoid a relapse.
Remember, contact your Vet for assistance and discussion of treatment first, if possible.