Friday, February 3, 2023
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Polioencephalomalacia – A Danger for Young Goats, Sheep and Cattle

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In 2002, I was raising 60 baby goats by hand. We started them in a barn, and by Spring had transferred them to pasture where they were learning to graze. One morning, during my usual check on them, I noticed one was acting oddly. He didn’t seem to be able to see, and was turning in circles. I pulled out the only resource I had at the time, the Goat Health Handbook: A Field Guide for Producers with Limited Veterinary Services by Thomas Thedford, DVM, and flipped through to the diagnostic pages. The symptoms matched up with Polioencephalomalacia (PEM). The treatment was 5 to 10 mg/kg of thiamine (vitamin B) half injected in the muscle and half in the vein. I checked with my project vet, and he told me to go for it. It was so easy and so fast – the kid was up and back to normal in no time at all.

What Is PEM?

Though folks shorten the tongue-twister of a name to “polio”, it has absolutely no relationship to the human disease. A common metabolic problem for young ruminants, it is generally a result of a thiamine deficiency. According to Richard Erhardt, a small ruminant extension specialist at Michigan State University, “Thiamine is not produced in animal cells but is produced by rumen microbes, which provide the major source of thiamine to adult sheep and goats. Milk-fed lambs and kids must get thiamine preformed from their diet to meet requirements. But then as they transition to becoming ruminants, they rely on their rumen microbes to synthesize thiamine as their thiamine source.” The incidence of PEM tends to be higher in during the period as young animals transition to becoming full ruminants.

PEM can also be a result of “thiaminase” ingredients in feed and forage. Thiaminases cause a breakdown of thiamine so that the body can’t absorb it. Sulfur is an example that has been well-documented in cattle, but can affect goats and sheep as well. Sources can include water, feed ingredients, and forages. For example, some ethanol plants sometimes process distillers grains in a way that increases the sulfur content, and some forages, like turnips, rape and mustard are also high in sulfur. Mold in grain is another example, and was the reason for my goat kid’s problem. The fellow who worked for me had left the grain out, it was rained on, and he fed it to them in spite of the mold.

What Are the Symptoms of PEM?

From the Goat Health Handbook, here are the symptoms to watch for. Though Dr. Thedford is describing goats, the symptoms are the same for sheep and cattle.

“The goat shows sudden loss of appetite, depression, no fever, and normal or slightly reduced rumen motility. Nervous system signs are head pressing, grinding of teeth, aimless wandering, blindness, abnormal eye movements, muscle tremors, and overreaction of jumping when touched. When the goat is unable to stand, the head usually will pull back. Convulsions and death follow in a few hours.”

Here are some additional symptoms from Richard Erhardt:

“Thiamine deficiency and/or high sulfur levels within the brain cause destruction of neurons and swelling of the brain which can be diagnosed by histological examination of brain tissue. Therefore, PEM symptoms are manifest as neurological, with early symptoms being partial to complete blindness with the head held erect. This may also be associated with unilateral (uneven) ear droop and/or unusual/exaggerated gait. It is common for the pupils to be dilated and for the eyes to tear. PEM affects animals of all ages but is most common in young lambs and kids transitioning from a milk to solid diet, and especially so in those fed a high-grain diet. PEM is also found in adult small ruminants of either sex at any age but more commonly associated with changes in diet (change in the plane of nutrition, pasture type, pasture to forage feeding, forage feeding to grain addition, etc.). PEM symptoms are similar regardless of age. Early blindness symptoms lead within hours to a day to loss of body control, inability to stand, and seizures. In more advances states, animals commonly arch their heads back as far as possible. PEM symptoms may present itself similarly to listeriosis and even ketosis. However, thiamine therapy is relatively benign, so it is best to treat with thiamine as a precaution.”

Thanks to Richard Erhardt for these photos.

How Can You Prevent PEM?

According to Erhardt, “Most cases of PEM are isolated and sporadic in nature and are associated with changes in feed of some sort. Therefore, it is difficult to develop an effective prevention program for these cases, although making gradual dietary transitions will certainly reduce the incidence of PEM along with many other health concerns.” For those finishing lambs or kids on diets low in fiber, adding fiber, particularly in a form that encourages rumination can also reduce problems. This means forage or chop longer than three inches. Adding feed grade thiamine is expensive and its usefulness hasn’t been thoroughly evaluated. An alternative would be to add high protein

Talk to Your Vet

I am not a veterinarian, nor is Richard Ekhardt, who’s quoted in this piece. This is just information you can use to inform yourself. Be sure to consult your own veterinarian about PEM and any other problems you may find in your herd.

If you have information to add here, please do! Many heads are always better than one!

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Kathy Voth
Kathy Vothhttps://onpasture.com
I am the founder, editor and publisher of On Pasture, now retired. My career spanned 40 years of finding creative solutions to problems, and sharing ideas with people that encouraged them to work together and try new things. From figuring out how to teach livestock to eat weeds, to teaching range management to high schoolers, outdoor ed graduation camping trips with fifty 6th graders at a time, building firebreaks with a 130-goat herd, developing the signs and interpretation for the Storm King Fourteen Memorial trail, receiving the Conservation Service Award for my work building the 150-mile mountain bike trail from Grand Junction, Colorado to Moab, Utah...well, the list is long so I'll stop with, I've had a great time and I'm very grateful.

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