The “wandering” calf – CCN Season

Like clockwork, last week I received a call out of hours to a calf found collapsed in a field, CCN immediately sprung to mind. The calf was seen lying away from the others in the group, the typical “lone ranger” sign of CCN. 

The farmer also mentioned that the calf appeared blind when he tried to stand her up, with a “vacant gaze”. Sometimes I get calls from the “wandering” calf that is separated from the others, looking aimlessly up into the sky. It is known as “Star Gazing” which is a pretty adaptable description. He had also noticed the evening before she was a little slow to come to the trough for ration.

CCN is a deficiency in Vitamin B1 which then causes these clinical signs in growing calves from six to 18 months old. Lambs can also be affected from two to six months old, showing similar clinical signs. The lack of Vitamin B1 causes inflammation in the brain that leads to neurological symptoms and swelling of the optic nerve that impacts the calf’s sight.

Due to the blindness, the calf can become dehydrated as they cannot find their way to the water trough. The fact this disease is very much seen in the summer in Ireland, if the sun does make an appearance it can accelerate this dehydration. An interesting finding on post-mortem is that under UV. Light the brain tissue glows bright green, demonstrating the inflammatory response.

You might wonder why this is mainly a summer disease at grazing? The main root cause is poor rumen health and the subsequent production of Vitamin B1 by the rumen microbes. The main source of vitamin B1 in the calf is from these microbes that exist in the rumen, they can absorb some from food sources but this is minimal. 

If the calf experiences an episode of acidosis from too much lush grass plus additional concentrates, the rumen pH will fall and will cause an imbalance in the Vitamin B1-producing microbes. Excess sulphur intake from grass is also linked to CCN due to its effect on Vitamin B1 production.

Ensuring good rumen health is key to the prevention of not only CCN but also goes hand in hand with summer scour prevention. We now add a fibre source to the field for the first three months of grazing, this helps to buffer the acid in the rumen and encourage good microbial health.

Extra fibre can be added to the ration you buy for calves also, discuss with your nutritionist for further advice on this. We have started to strip graze our larger calf paddocks this year also which encourages the calf to eat the whole grass just the lush sugar-dense top leaves. On the farm we also use a calf mineral lick which contains a high level of Vit B1, Badger-proofing licks are always advisable as a TB prevention method.

The treatment for this calf consisted of initial supplementation of Vit B1 slowly given intravenously alongside a steroid to reduce brain tissue inflammation The response to treatment can be very variable, so it is important to continue to supplement Vit B1 intramuscularly for three to four days after initial treatment.

It is the aftercare of this calf is extremely important they can remain blind for some time, so supplementing water orally to prevent dehydration and encouraging intake of feed is essential for survival. I warned the farmer to watch for early signs in the other calves as it can be a group issue with numerous calves affected. This is because usually, more than one calf will have experienced acidosis.

Unfortunately, calves don’t always pull though, early diagnosis by your vet is so important to limit the damage. Other diseases can look like CCN, such as meningitis, listeriosis or even lead poisoning so it is always important to call your vet. This particular calf is still alive, she is currently housed and getting lots of TLC.

The Greek island of Rhodes is calling this week, looking forward to a week away, I have a feeling it will be a mini Cork over there with the new direct flight. Back in March, it seemed like a dream during those miserable rain-filled days, it was difficult at the time to think we would one day be boarding the plane. Difficult times are soon followed by lighter and brighter days.

• Hazell Mullins BVM BVS, is a large animal vet based in Carrignavar, Co Cork.