Suzanne Poland: Vitamin B1 deficiency is a stock disease farmers need to watch out for

If polioencephalomalacia is left untreated, it results in death. Photo / Devyn Staines

OPINION

Polioencephalomalacia is a neurological disease that affects ruminants. Farmers need to watch out for symptoms and contact the vet promptly because this disease can progress quickly, writes vet Suzanne Poland.

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

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

PEM is a neurological disease that 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 stargazing.

As the disease progresses, the animal can become stiff in the legs or will become cast, and 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 because this disease can progress quickly.

B1 deficiency is not caused by a deficiency in the diet; ruminants’ Vitamin B1 is produced by the microflora in the gut.

Instead, the deficiency occurs 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.

Read more about animal health here.

Vitamin B1 has an important role in the nervous tissues — deficiency causes a swelling of the brain that leads to the neurological signs listed above.

The response to treatment depends on how advanced the disease has become.

While the B1 deficiency can be treated, if the brain damage has gone too far the animal will not make a full recovery.

If the disease is discovered early enough, there can be a good response to treatment.

Where possible, make any changes to the diet of animals 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 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.

Suzanne Poland is a large animal veterinarian at Vetora Te Awamutu.