07 February 2023

Pre-lambing health treatments for the ewe flock

For mid-season lambing ewes, the final pre-lambing health treatments are currently taking place or are due to happen over the coming days and weeks. Damian Costello, Teagasc Sheep Specialist, Teagasc Athenry, outlines the main health treatments being administered on sheep farms around now.

Clostridial/Pasteurella vaccination

Clostridial/pasteurella diseases remain a major cause of mortality in sheep despite the presence of relatively cheap and highly-effective vaccines. Vaccination is essential to reducing losses due to these conditions as generally the first noticeable clinical symptom is death, which leaves little option for treatment. In all cases farmers need to follow manufacture's instructions carefully in terms of product storage and correct administration. Most products are administered by subcutaneous injection, with the loose skin on the upper side of the neck being a suitable site. Cleanliness is essential throughout the process including regular replacement of the needle. It is generally not recommended to conduct vaccinations on sheep with wet fleeces, as it can result in contamination of the needle and abscess formation.

Each animal must complete a full primary course of vaccination. This requires two doses given four to six weeks apart (read manufacture's instructions). It is important to note that if changing from say one of the 8 in 1 products to a 10 in 1 that the two shot primary course is required to achieve full cover. Onset of immunity will not occur until two weeks after the primary vaccination has been completed. Active immunity in animals that have received the full course is reported to last up to 12 months. Remember a single shot is not sufficient. Once the primary vaccination course has been completed an annual booster needs to be administered within to the 12 month period to facilitate re-vaccination.

In the case where retained ewe lambs are not mated and have received their primary vaccination at say 10 weeks and 14–16 weeks of age, it’s a good idea to administer a booster to these animals when treating the breeding flock pre lambing, so that they are lined up with the flock for their annual booster in subsequent years. In addition to the ewe flock, it is important not to forget to give the rams their annual booster to afford them protection, as they are often overlooked. Where farmers operate split-lambing flocks, they may need to consider vaccinating these batches on separate dates to ensure they fall within he recommended vaccination window.

Passive immunity is the transfer of maternal immunity to new-born offspring that occurs via colostrum provided that the ewe has been vaccinated four to six weeks pre lambing. Remember sufficient amounts of good quality colostrum must be consumed by lambs within the first 24 hours of life. The duration of passive immunity is variable and as passive immunity declines lambs will need to be enrolled on a vaccination programme to provide cover. It is advisable to seek veterinary advice as to when vaccination of lambs should be carried out if this is a particular issue on your farm.

Internal Parasites

In the case of liver fluke infection, aim to treat immature and mature stages at this time of year. If housing sheep, delaying treatment for six weeks post-housing means flukicides containing closantel, nitroxynil or rafoxinide should be effective to remove all fluke present. Do not use a combined fluke and worm product on mature ewes, as adult ewes have good immunity to stomach worms and do not require routine treatment. There is no performance benefit in treating the mature healthy ewe for stomach worms and it speeds up the development of anthelminthic resistance. Lactating yearling ewes are one exception and may warrant a worm drench.

Lameness

As always, it is important to keep on top of any lameness issues; lameness depresses feed intake, making affected ewes less inclined to compete for feed. If left untreated, lame sheep will lose body condition and can be at risk of developing metabolic diseases. Separate and treat lame cases promptly, consulting with your veterinary surgeon if necessary for diagnosis and prescription of appropriate treatment. When ewes are in the handling yard for vaccinations/fluke dose, take the opportunity to footbath the flock. As for all treatments close to lambing, it’s important to move and handle ewes in a stress-free manner.