More commonly called “goat polio” or simply “thiamine deficiency,” polioencephalomalacia is a neurological disease characterized by brain swelling and tissue death – the word literally means “softening of the brain.” Ruminants harbor beneficial bacteria and protozoa that produce Vitamin B12 (cobalamin) and Vitamin B1 (thiamine) under normal environmental conditions. If this production is interrupted, thiamine deficiency can occur. To put it simply, the rumen must be kept happy to produce thiamine; thiamine is necessary for proper nerve conduction, and neurological signs present when thiamine is lacking.
Pre-ruminant goat kids rely on dietary thiamine – goat milk and colostrum contains B vitamins. Low-quality colostrums or milk replacers or whole milk recipes lack the essential B vitamins for optimal kid health. Many factors can contribute to reduced or cessation of normal thiamine production in ruminants.
Dietary causes include too much grain and not enough roughage, consumption of moldy feedstuffs, diets high in sulfur, cobalt-deficient diets, or consuming certain toxic plants – such as bracken ferns.
Sudden changes in the diet, especially increased or excessive grain consumption, can decrease the PH in the rumen and disturb the thiamine production of the microorganisms there. Excessive grain rations or moldy feedstuffs can be problematic because each contains certain enzymes that produce thiaminases. Thiaminases inactivate or degrade thiamine molecules, leaving the goat thiamine-deficient. Bracken ferns – while toxicity symptoms vary widely based on dose, duration, and species of affected animals – contain thiaminases, and thiamine deficiency has been noted in sheep grazing on the plants in Australia.
Diets high in sulfur – foodstuffs or water or a combination of the two – can also lead to thiamine deficiency. According to “Digestive System and Nutrient Needs of Meat Goats” by Purdue Extension, “Sulfur produces thiamine-like compounds called analogs that decrease the absorption of thiamine in the rumen.” There are many possible sources of excessive sulfur, including: water sources, alfalfa, cruciferous plants, distillers grains, and corn, sugar beet, and sugar cane byproducts. According to Goat Medicine by Mary C. Smith and David M. Sherman, “Extrapolating from recommendations based on cattle and sheep, the maximum total dietary sulfur in high concentrate diets is 0.30% and 0.05% if the diet consists of at least 40% forage. Drinking water should contain less that 600mg/L sulfate/L for high concentrate diets, whereas 2,500 mg sulfate/L is acceptable with higher forage intake (NRC 2005.)” Generally speaking, sulfur should not exceed 0.3% total diet dry matter.
Cobalt-deficient diets are also precursors to goat polio. The trace mineral is essential for the microorganisms to manufacture and utilize Vitamin B12. Vitamin B12 is essential to maintain nervous system integrity and promote red blood cell synthesis. Certain areas in the U.S. are known to cobalt-deficient – a map can be found at http://www2.luresext.edu/goats/training/nutrition.html. Sandy soils and alkaline soils are more likely to be cobalt-deficient. Though not much research has been conducted on goats specifically, it has been established that goats require a very small amount of cobalt and are less sensitive to cobalt deficiencies than sheep. Sufficient daily cobalt intake is between 0.1ppm and 0.3ppm. Toxicity can occur at 10ppm.
Infectious and parasitic diseases increase thiamine requirements and can lead to goat polio if those requirements are not met. Since antibiotics do not distinguish between beneficial or harmful organisms, antibiotics can diminish the beneficial gut flora responsible for thiamine production.
Amprolium – the active ingredient in some coccidiostats such as CORID® – works by blocking thiamine uptake of certain coccidian protozoa that require more than the host. Misuse or long-term use can result in thiamine deficiency in the goat, especially if the goat experienced dietary thiamine deficiencies already.
Symptoms of Goat Polio
- Off feed/water
- Involuntary eye movements
- Temporary blindness
- Sudden death
Note: Stargazing is characterized by the goat’s head thrown backwards due to rigid neck muscles. Temporary blindness may last as long as 2-3 weeks. Diarrhea, while not a neurological symptom, can present because the rumen is not functioning properly.
Severe thiamine deficiency can possibly kill a goat in 24 hours to a few days if left untreated. Goats are more likely to die from poor rumen function or inability to eat. Correct treatment usually results in quick improvement. The only effective therapy is supplementing thiamine.
Very severe cases might require an intravenous treatment performed by a veterinarian. Fortified Vitamin B complex injections are more commonly used, and can be given subcutaneously or intramuscularly. The dosage will depend on the concentration of thiamine – for supplements containing 100mg of thiamine the common dosage is 1cc per 20lb. B Vitamins are water-soluble and excess is excreted through the urine.
Injections should be given every six hours as needed. Taper off treatments gradually, lengthening time between injections, to monitor for potential relapse. If the goat is truly experiencing goat polio, improvements can be seen in as little as minutes or hours. If no improvement is noticeable, consider consulting your vet about treating simultaneously for Listeriosis, which has very similar symptoms but is more common in adult animals. Read more about Listeriosis at Merck Veterinary Manual online.
By Kendra Shatswell
Article reviewed by Dr. Ken Brown DVM
“Animal Sciences Common Diseases and Health Problems in Sheep and Goats” – Purdue Extensions.
“Digestive System and Nutrient Needs of Meat Goats” – Purdue Extensions.
“Dietary Sulphur in Ruminant Diets” – Westway Feed Products
“Polioencephalomalacia (Goat Polio)” Alabama and Auburn Universities UNP-65 – Maria Leite-Browning, DVM, MS Extension Anima Scientist Alabama A&M University.
“Ramifications of Thiamine Deficiency” – Department of Natural Resources, Cornell University, 2017.
Goat Medicine Mary C. Smith and David M. Sherman.