Vet's corner: Dealing with milk fever

This low blood Calcium (Ca) or hypocalcaemia is referred to as ‘milk fever’. The most recent case I saw was in an older Holstein Friesian cow this morning that calved a day ago and suddenly went down. When I arrived, she was stretched out with all the symptoms of milk fever.

An important thing to do is sit or prop the cow up to prevent bloating when they are stretched out. When a cow calves, she suddenly has huge demand for Ca directly related to milk production. In some cases, the cow’s body cannot meet these demands, which in turn lowers blood Ca and causes muscle weakness and recumbency. Ca plays a very important role is muscle tone and function.

Treatment

While most farmers will recognise and treat milk fever themselves, it is important to check the cow for other problems, including mastitis. If a cow has received treatment and is not responding, the vet should be called.

When a cow is staying down, there are probably other issues complicating her recovery. I will often see a concurrent injury due to milk fever which can benefit from pain relief and moving the cow to a well bedded comfortable environment.

Cows can get weak and I will often give oral rehydration and propylene glycol in warmed fluids to help the body recover. Another thing I will do for a cow that has been down for more 12 hours will be to give oral K, which in a downer cows can be leached out of the system and not replenished. Your own vet is best placed to give advice on individual cases.

When there is high incidence of milk fever, this needs to be investigated. It is the iceberg effect, Two cows going down could lead to 20 cows or more contracting subclinical ‘milk fever’. This has huge a knock-on effect on the group’s performance due to immunosuppression; they are more prone to infections mastitis and metritis.

The way to counteract this at herd level is to look at dry cow diet. Before a cow calves, she should have very little Ca in her diet or anything else that will effect Ca metabolism. She also needs a good supply of Mg. Then, when required, she can mobilise Ca quickly from her bones.

At herd level, I will often look at urinary ph. of batch of dry cows. This is directly linked to rumen ph. By measuring this, I can determine whether rumen is acidotic or alkolotic.

For a freshly calved cow to mobilise Ca, she will need her rumen to be mildly acidotic precalving. So I will add a DCAD rumen acidifier precalving for a few days to increase Ca mobilisation when she calves. This technique has worked very well for me at herd level, but farms vary and your own vet is best placed to advise you. I would also make appropriate adjustments to the dry cow diet to alter Ca metabolism.