The cost of an abortion can be significant. It has been estimated that loss of a calf, unplanned culling, loss of milk and genetic wastage, cost about £630 for a dairy cow in the UK. Abortions to a certain degree are unavoidable, however, when either the number of abortions reaches a threshold of above 3 per cent or you have a quick flurry in a short space of time, then it is often worth investigating, says Mr Barber.
All cattle owners must notify the Animal and Plant Health Agency (APHA) of abortions which occur on their farm with the definition of an abortion being a calf which is produced less than 271 days after service regardless of whether it is born dead or alive. This reporting is to maintain and provide evidence for the country’s brucellosis-free status, a system which has proved successful but which can only continue if the reporting of abortions continues.
Mr Barber says if the decision is made to investigate, it is vital to provide a complete history including whether any illness was present in the aborting dam, as well as any other problems surfacing in the rest of the herd. While some sick animals abort just as a consequence of a high temperature, some animals may have a particular abortive disease and show specific concurrent symptoms to go along with it – one example being IBR, a virus with the ability to cause both abortions and respiratory signs.
He says: “With some infections causing abortions during certain stages of pregnancy, it is useful to know the stage at which cows are aborting. While abnormal interservice intervals are commonly due to incorrect identification of oestrus, it can also be an indicator of early loss of the embryo and should also be considered as part of the investigation.”
Unfortunately a diagnosis is not reached for thousands of abortions every year. While this is likely due to many cases not having an infectious cause, there is also the certainty there are infections about which we still have no knowledge of.