Thiamine deficiency in young stock. What it is, why does it happen, signs to look for and options for treatment and prevention.
The disease is known by many names, but alas are all the same. You may have heard of – thiamine deficiency, Vitamin B1 deficiency, Polio, PEM (polioencephalomalacia), or CNN (cerebrocortical necrosis). The name “polio” is often used as a shortened version of polioencephalomalacia, this is not to be confused with the human polio virus as they are completely different diseases.
What is it?
Vitamin B1 (also known as thiamine) is a vitamin that is produced by bacteria in the rumen. Ruminants have a daily requirement of thiamine, and the bacteria will normally produce enough to meet this.
When animals become deficient in vitamin B1, they develop a neurological condition due to swelling in the brain. It is most commonly seen in early summer in well grown calves between 6-12 months old, and lambs between 2-12 months old, however all ages of sheep and cattle can be affected.
The disease typically only affects a few animals and outbreaks are uncommon.
Why does it happen?
The most common cause of vitamin B1 deficiency is when the rumen grows too many bacteria that produce thiaminase enzymes. These enzymes will destroy any vitamin B1 made in the rumen, leading to a deficiency in the animal.
In New Zealand, this most often occurs when animals change from a rough quality diet to one high in carbohydrates like lush pasture. Other ways stock may become deficient is by eating plants containing thiaminase, such as Bracken fern, horsetails or Nardoo, or having diets high in sulphates like brassica crops.
Signs to look out for?
Signs usually start off mild and progressively get worse as the brain continues to swell.
- Blindness and/or “star gazing”
- Staggering
- Isolation and/or depression
- Wandering aimlessly
- Circling and/or head pressing
- Death
Treatment
Rapid treatment with vitamin B1 injections is required. Response to treatment is rapid and animals usually recover in 12-24 hours. If treatment is delayed it can lead to death or permanent brain damage in severely affected animals
Can I use a B12 injection to treat/prevent the condition? Unfortunately, no. Commercially available injectable vitamin products such as Smartshot® B12 or Duomax B12 do not contain the vitamin B1 (thiamine) needed to treat the condition.
Prevention
- Introduce stock onto good quality feed slowly
- Provide lots of fibre with high carbohydrate diets
- Limit sulphates such as brassica crops and water with high Sulphur levels
- If you have had problems with vitamin B1 deficiency, supplement during risk periods with a B1 drench. Ask your vet for more details
If you would like to discuss thiamine deficiency or your stock is showing symptoms, please do not hesitate to contact us.
