Pressure is increasing on the veterinary industry to help minimise the use of medications in all livestock production. However, the good news is that for many diseases, prevention is better than cure. And there are many diseases of sheep for which vaccines are currently widely available – for commercial flocks, smallholders, or pet sheep.
The two most effective vaccines used in sheep are Clostridial and Pasteurella vaccines, these may be given separately or more commonly given in combination.
Clostridial Disease and vaccination
There are a number of clostridial diseases that affect sheep. These are a serious threat to those sheep which are yet to be vaccinated. These diseases can sadly cause death in as little as a few hours.
The most common types of diseases found in sheep are tetanus, lamb dysentery, blackleg, black disease, pulpy kidney, struck and braxy.
All sheep should be vaccinated for tetanus and 2 types of enterotoxemia. In most cases, this is given as a combined vaccine. This vaccine should be given to pregnant ewes four weeks before lambing and supplies the protective antibodies which the newborn lamb will obtain by the colostrum.
Lambs should also receive the vaccine at 6-8 weeks of age, followed by a booster 4 weeks later and again at the time of weaning.
Pasteurellosis and vaccination
Pasteurella is a respiratory pathogen that causes health problems in all ages of sheep. Problems range from septicaemia in lambs, mastitis in ewes and pneumonia in older sheep.
Pneumonia in older sheep can occur outdoors but cases have been shown to be more frequent in sheep which are kept indoors. This can be due to the following:
- Poor ventilation resulting in a build-up of noxious gases in manure
- Higher levels of humidity
- Accumulation of pathogens because of high stocking-density
- Close contact leading to the easy spread of pathogens
- Stress can occur due to overcrowding
When pneumonia does happen in sheep, it usually occurs not only because of several of the factors mentioned above, but because there could be more than one microorganism causing the pneumonia.
Pathogens (disease-causing microbes) in sheep are frequently found in combination and it is probable that damage by one organism may facilitate infection by another. Subsequently, it can be difficult to figure out which pathogen is causing the problem.
Vaccination in breeding ewes is recommended with a primary course of 2 injections, 4 to 6 weeks apart followed by an annual booster 4 to 6 weeks before lambing. Lambs are given 2 doses of the vaccine from as early as 10-days of age.
There are now a number of combination (or multivalent) vaccines which combine protection against Pasteurella and a range of Clostridia. These are probably the most widely used, and should be considered essential to keeping your flock healthy in most situations. They are the “core vaccines” for the species, like parvo and distemper in dogs or panleukopenia in cats.
Foot Rot and vaccination
Foot rot is an extremely painful disease in sheep. It causes affected sheep to graze on their knees and rapidly lose weight. Foot rot results in the foot becoming inflamed and smelly, so prevention is often better than cure.
Foot rot is also known as foot scald and mainly occurs in wet areas. Sheep should be vaccinated every 3-6 months and should always be vaccinated in spring, before a rainy season.
Vaccination alone will not stop foot rot, but it is a useful tool. Other ways in which foot rot can be prevented is to improve drainage, restricting access to boggy areas, foot-trimming and foot bathing.
Orf (Contagious Pustular Dermatitis) and vaccination
Orf is a skin disease affecting sheep (and goats). It shows as scabs and sores around the hoof junction and mouth of the sheep. This means that infected lambs are therefore unable to suckle due to the discomfort of the scabs on their mouths. They do not thrive, so ewes should be vaccinated well before lambing begins.
Unfortunately, should infected lambs manage to suck, there is a significant increase in the spread of the disease to the ewes’ teats. This can cause considerable pain and discomfort for the ewe, and she may push the lamb away as it tries to feed. Orf is a zoonotic disease (can spread to humans), so great care must be taken when managing infected sheep with orf.
Orf vaccination is a live vaccine which should be used 6 weeks before the expected occurrence of disease. It is administered by scratching the skin (scarification). The vaccine should only be used on farms and smallholdings where infection is present.
Where no orf is present, using the vaccine can reduce the risk of introducing it to the farm/smallholding.
Louping ill and vaccination
Louping ill is an acute viral disease spread by ticks (Ixodes ricinus) and can lead to death. Controlling Louping ill can be achieved through tick control, or through vaccination.
The vaccine supplies immunity within 4 weeks and has been shown to be effective for at least 18 months. However, this vaccine contains mineral oil, which means that self-injection can cause serious swelling and even the loss of a finger, so great care must be taken by farmers when administering it.
Abortion and vaccination
Sadly, lambs can be lost at any stage of pregnancy, but it is normally the problems encountered at the latter stages of pregnancy which are most common, such as abortions and stillbirths.
Common cause of abortions is shown to be caused by infection; or the sheep may have had a period of stress.
There are numerous infectious agents involved in abortion. These include Campylobacter; Chlamydia and Toxoplasma, with the last two being prevented by vaccinations. If a farm or small holding is having problems with abortion, then they must isolate affected ewes and have good hygiene protocols in place to limit the spread of disease.
Both vaccines must be used prior to breeding and not in pregnant ewes or those that are about to be mated. They should be given to ewes 4 weeks before tupping.
If you are having problems with abortion or still births, please speak to your veterinary surgeon who will help to diagnose the cause of this.
If you have any concerns about the types of vaccinations available or need advice on how to vaccinate, please speak to your RAMA or veterinary surgeon.