Polioencephalomalacia (Thiamine Deficiency) in Alpacas

Emergency — call your vet now

This condition can kill within hours. Get veterinary help immediately.

Brain swelling caused by thiamine (vitamin B1) deficiency or excess sulfur. Fast treatment can be life-saving.

Category: Neurological
Urgency: Emergency
Also called: PEM, Polio

Signs & symptoms

Apparent blindness, bumping into objects
Star-gazing (head tilted back)
Head pressing, muscle tremors
Seizures and recumbency

What causes it?

Disrupted fore-stomach microbes after grain overload or sudden diet change, thiaminase in plants (bracken, horsetail), excess sulfur in water or feed, or overuse of amprolium.

Risk factors

Grain overload or abrupt feed changes
High-sulfate water
Bracken or horsetail in hay

How vets diagnose it

Clinical signs and rapid response to thiamine.

Treatment

Emergency thiamine injections and anti-inflammatory therapy by a vet; response is often seen within hours.

Do not wait to see if it improves. Camelids hide illness, and by the time signs are obvious the problem is often advanced. Call your veterinarian.

Prevention

Change diets gradually
Test water sulfate in arid regions
Keep bracken and horsetail out of hay

Background

Polioencephalomalacia (PEM), also referred to as cerebrocortical necrosis (CCN), is a neurological disease seen in ruminants that is caused by multiple factors, one of which is thiamine depletion in the body. Thiamine is a key chemical in glucose metabolism that, when deficient, is most threatening to neurological activity. In addition to altered thiamine status, an association with high sulfur intake has been observed as a potential cause of PEM. PEM may also be caused by other toxic or metabolic diseases such as: acute lead poisoning or salt poisoning. Cattle, sheep, goats, and other ruminants that are diagnosed with PEM or pre-PEM suffer opisthotonus, cortical blindness, disoriented movement, and eventually fatality, if left untreated. Current data shows that the onset of PEM can range from birth to late adulthood.From Wikipedia — “Polioencephalomalacia”, licensed under CC BY-SA 4.0.

Research & references

PubMed lists 4 peer-reviewed papers on this topic in camelids. The most relevant include:

Polioencephalomalacia in a llama. Himsworth CG The Canadian veterinary journal = La revue veterinaire canadienne, 2008. PubMed 18624072 · cited 3×
Neurologic diseases in llamas and alpacas. Whitehead CE, Bedenice D The Veterinary clinics of North America. Food animal practice, 2009. PubMed 19460647 · DOI · cited 28×
Polioencephalomalacia in two alpacas. Beck C, Dart AJ, Collins MB et al. Australian veterinary journal, 1996. PubMed 8941412 · DOI · cited 7×
Gross and microscopic lesions of polioencephalomalacia in a llama (Lama glama). Kiupel M, VanAlstine W, Chilcoat C Journal of zoo and wildlife medicine : official publication of the American Association of Zoo Veterinarians, 2003. PubMed 14582798 · DOI · cited 6×

Frequently asked questions

What is polioencephalomalacia (Thiamine Deficiency) in alpacas?

Brain swelling caused by thiamine (vitamin B1) deficiency or excess sulfur. Fast treatment can be life-saving.

What are the signs of polioencephalomalacia (Thiamine Deficiency)?

Apparent blindness, bumping into objects, star-gazing (head tilted back), head pressing, muscle tremors and seizures and recumbency.

How do you prevent polioencephalomalacia (Thiamine Deficiency)?

Change diets gradually. Test water sulfate in arid regions. Keep bracken and horsetail out of hay.

Is polioencephalomalacia (Thiamine Deficiency) an emergency?

Emergency — call your vet now. This condition can kill within hours. Get veterinary help immediately.

This page is educational and does not replace advice from a veterinarian who has examined your animals. Camelid medicine uses many drugs “extra-label”, so dosing must come from your vet. In an emergency, call your vet first. Read our disclaimer · How we write and review content.