Seasonal issues

Dr Jeff Cave, Agriculture Victoria, Wodonga

A key to understanding current health issues in sheep, as well as predicting those which are around the corner, is to consider the environmental conditions recently being experienced.

In a nutshell, we have just experienced three wetter than average years with record breaking rains last spring.

For internal parasites this has meant favourable conditions for the survival of the environmental stages of the parasite’s life cycle. Consequently, summer drenching hasn’t achieved the desired reduction in parasite burdens. Furthermore, parasite clean paddocks to put sheep onto after drenching are harder to find and are often relatively heavily contaminated with parasite larvae.

The end result of this are sheep with relatively high internal parasite burdens, despite regular drenching. As we move towards winter this is likely to remain a problem particularly in the sheep most susceptible to internal parasitism i.e., ewes at the point of lambing and weaners.

Regular monitoring through faecal egg counts coupled with an appropriate drench program is going to be of particular importance this season. Wormboss contains good practical tips if you are considering using long-acting drenches.

The wet conditions have also led to an increased incidence and severity of foot conditions, both of footrot for those flocks which have it, and foot abscess. The prolific population of flies compounded the problem with a high incidence of fly struck feet being seen. The recent dryer conditions may have alleviated the acute stage of the disease process but the aftermath of what we saw in spring remains.

Firstly, a notable reduction in condition score may be seen in sheep which have struggled with foot conditions. Secondly, poor scanning results may be seen, which may have resulted from rams being lame during joining. In some cases, ewes may have aborted during early pregnancy due to the stress of lameness.

Naturally, the severity of any sheep health issues will vary from property to property as will their most appropriate management, which are best solved in consultation with your local veterinarian.

Acknowledgement: Thanking Dr Tristan Jubb of Bendigo Sheep Vets for sharing his observations and thoughts which helped form the basis of this article.