Watch out for B1 deficiency in stock

Polioencephalomalacim (PEM) or vitamin B1 (thiamine) deficiency is something that vets often see around this time of year.

However, it is a sporadic disease and so while it is common for us, it is not common at the farm level.

PEM is a neurological disease which affects ruminants; cattle, sheep and goats. It usually occurs in young stock post weaning but can also be seen in older ruminants.

The most distinct sign of this disease is blindness. The initial signs are often head pressing, frothing at the mouth, and a staggering walk. The blindness can sometimes result in the animal walking around in circles or star gazing.

As the disease progresses the animal can become stiff in the legs or will become cast. As the disease progresses the animal may develop seizures. If left untreated this disease will result in death.

If you have a blind animal, or suspect B1 deficiency it is best to get your vet out ASAP as this disease can progress quickly.

B1 deficiency is not caused by a deficiency in the diet; ruminants get their vitamin B1 produced from the microflora in the gut. The deficiency occurs instead due to something called thiaminase which breaks down the B1 in the gut. The thiaminase can either be produced by gut microflora or can be present in some plants.

A sudden change in diet for ruminants causes a change in rumen microflora (such as moving from lush pasture to stalky pasture or vice versa). In the case of PEM this leads to an increase in bacteria producing thiaminase. Thiaminase breaks down the B1 before the animal can absorb it, leading to a deficiency. B1 deficiency has also been caused by diets high in sulphur.

Brassicas, molasses or sulphur in fertilisers can contribute to this. Vitamin B1 has an important role in the nervous tissues, in deficiency it causes a swelling of the brain which leads to the neurological signs listed above.

The response to treatment depends on how advanced the disease has gotten. While the B1 deficiency can be treated, if the brain damage has gone too far the animal will not make a full recovery. If early enough in the disease then there can be a good response to treatment.

Where possible make any changes to the diet gradually. If there is a high sulphur feed or a sulphur fertiliser was used on the grass; a feed sample analysis can be done to check the sulphur content of the feed before feeding out to stock. In the case of an outbreak oral B1 can be given to the healthy calves for prevention.

If any of these neurological signs are seen in your stock get in contact with your vet as soon as possible.