Over the last month we have seen an outbreak of an uncommon condition called dropped hock or sciatic palsy on one of our dairy farms. This is a new condition of unknown cause that has only been recognised in New Zealand since 2011. It affects rising 2 or rising 3 year old animals just prior to calving. In this case they were all rising 2 year olds. The heifers go from having a mild shifting hind limb lameness through to some animals being unable to stand because their hocks remain on the ground. This happens when the muscle in their leg ruptures. This is the first time our practice has seen an outbreak of the disease, but we have seen the odd individual with similar signs in the past. In this outbreak there have been 22 animals affected. Not all heifers go on to have hocks that touch the ground, but some have had to be euthanased. Interestingly all the heifers tested have had very low copper levels. While it is currently unknown what the exact cause is, there is a suspicion that inadequate copper supplementation is part of the problem. Copper is crucial to the formation of collagen which makes tendons in animals. There is also a suspicion that this condition is related to the humeral fractures that we have been seeing in recent years.
If you see any heifers with this condition or think they have this condition contact the Veterinary Centre. It is also import to ensure that adequate copper supplementation is going into your young stock.