Cerebrocortical necrosis (CCN) – a nervous disease in cattle and sheep caused by disrupted thiamine production in the body.
One evening recently, a client phoned saying he had a bullock that was on grass and behaving very unusually. He was falling on the ground and paddling, trying to get up but on getting his legs under him failing to rise and ending up in a dog-sitting position with his head held high and shaking. The animal was about 550kg and was on the farm about a month and was on a field of lush grass.
The symptoms were definitely those of a brain problem. At this stage, the diagnosis is a process of elimination as the following conditions come to mind: meningitis, listeriosis, lead poisoning, injury, tetany (very rare in male cattle), and cerebrocortical necrosis or CCN.
In the case of meningitis, one would expect a more gradual onset and probably an elevated temperature; listeriosis would likely have the animal walking in circles, again with an elevated temperature, and would not have come on as suddenly.
Lead poisoning will come on very suddenly if the animal had access to lead (in batteries, old painted gates or old horse carts, etc.) This was unlikely, given that this field is in pasture a long time and not near a public road from which hazardous material could have been thrown.
The most likely diagnosis was CCN. The animal was treated for this and while his prospects at the time looked poor, he had made an excellent recovery by the next morning.
Cerebrocortical (CCN) is a nervous disease seen in cattle and sheep that is caused by disrupted thiamine production in the body. Thiamine is necessary in glucose metabolism that, when deficient, is most threatening to nervous activity. Cattle and sheep diagnosed with CCN exhibit muscle tremors, blindness, disoriented movement and eventually fatality, if left untreated
Ruminants have working rumen bacteria that synthesise thiamine for the body. However, feed concentrates given to ruminants are often heavily stocked with thiaminases, which counter its production. High levels of sugars in feed can also result in thiamine inadequacy.
When there is a sudden increase of glucose in the body, thiamine will be depleted so that it is not available, resulting in induced deficiency. High concentrations of sulphur intake has also been deemed responsible for CCN. Sulphur is necessary for the synthesis of important sulphur-containing amino acids and proteins.
Luscious grass high in sugars and sulphates are seen as a likely predisposing factor to CCN. Immediate treatment is absolutely necessary to prevent death. The only advice one can give in seeking to prevent it is to make sure there is enough fibre in the diet.