In the middle of a busy bank holiday on call I received a phone call from a concerned farmer with a heifer bleeding from the nose.

I got in the jeep and headed out assuming from what he said that it was probably a condition called thrombosis. He said she had calved a day before and had suddenly gone off form.

Vena cava thrombosis is a condition where a large abscess develops in the main blood vessel in the chest, causing it to rupture and bleed from both nostrils. It has a terrible prognosis usually in the short-term.

On arrival on the farm from visual inspection my opinion had changed. The heifer was notably nervous and hyperaesthetic (wild), which he said was strange because she calved down fine and was usually a quiet animal.

The bleeding turned out to be from only one nostril which made it more likely to be trauma due to her agitated state. At this stage my trail of thought turned to meningitis or maybe nervous ketosis.

The next stage was the all-important physical exam. I was able to rule out meningitis but what alerted me was some of the clinical signs even though she was standing of grass tetany.

Mg controls nerve function so a drop in blood concentrations can lead to nervous type symptoms which of course would eventually lead to collapse quite quickly. Her heart rate was also twice the normal rate which I often see with grass tetany. She was in some distress and did not quite fit the bill for nervous ketosis. This is a condition due to certain by-products of acute negative energy in the blood causing severe nervous symptoms. This is a relatively uncommon condition.

We weighed up all our possibilities and because conditions were perfect for grass tetany we decided to treat her with Mg. Grass tetany can strike when there is reduced intakes due to bad weather and it doesn’t help that spring grasses are very low in Mg.

We gave her some subcutaneous Mg and some chanatol and anti-inflammatories to make sure we covered ketosis. I received a call from the farmer three hours later to tell me she was a different animal and was eating.

I don’t always get the right result like this but what it highlights is the risk of grass tetany this time of year. It showed me the importance of never making assumptions and that experience is a great teacher for us all.

When cows suddenly go off there usually something wrong, and with most of these conditions the earlier intervention the better.