OJD – A few years ago a friend of our sheep died of a mysterious illness. Whenever my husband came home to tell me about it, he could never remember what it was called.
“James disease? Johnson’s disease?” The name joked between us for a while.
After finding out the extent of OJD (or Ovin John’s disease), we realized it was no laughing matter.
Our friend lost all his animals because this disease is so contagious. She will not be able to raise sheep for many more years until her pastures are cleared.
This dangerous disease is fortunately quite rare, but when it does occur, it can be extremely serious. Here’s what you need to know.
What is OJD?
OJD, or John’s disease, is a fatal disease of goats, sheep and other ruminants including deer, elk, cattle and even bison.
It is caused by a bacterium called mycobacterium avium subspecies paratuberculosis. It is sometimes referred to simply as paratuberculosis.
It is a gastrointestinal disease that mainly affects young animals, although older individuals can also be affected. It is highly contagious, spreading rapidly through flocks of sheep.
Typically, it is spread through feces, when individuals become infected when they graze on the back of another infected person.
However, it is one of the few diseases that can be transmitted to the placenta as well as through the milk and colostrum of infected sheep.
Symptoms of OJD
There are several key symptoms of OJD to look for.
One of the biggest challenges in treating this disease is that most symptoms mimic symptoms related to other diseases.
The most obvious sign of infection is persistent weight loss, despite a good appetite and adequate diet. Diarrhea can occur, although it is relatively rare in sheep and more common in cattle.
It is a wasting disease that can take several months to years to eventually kill an animal.
Your sheep may not show symptoms until it grows a bit older, sheds bacteria in its feces and continues to contaminate the environment and other animals.
Another reason that Johann’s disease can be difficult to treat is that the conditions closely resemble internal parasitic infections.
Often, you will need a vet diagnosis (usually at necropsy) to determine the cause of the illness to be Johann.
Because OJD is a chronic infection of the bowel, the most common symptoms are related to weight loss. The lining of the intestine thickens and reduces the sheep’s ability to absorb food. It will continue to eat and drink normally until it is too weak to do so – you can see it eating the rest of the crowd.
Again, most sheep do not show signs of illness for very long after being infected. They will spread the disease until you know they have it.
The bacteria can survive for 12 months or more in a favorable environment, such as in wet areas of pasture or field.
how to stop ojd
Preventing OJD is important, especially when you consider that there is no known cure for the disease (which I’ll go into a bit more detail below).
Here are a few tips.
1. Maintain a Closed Herd
If you are concerned about John’s illness, the worst thing you can do is introduce more sheep to the herd.
Maintain a closed herd and don’t introduce John by adding more sheep.
When buying more sheep is absolutely necessary, buy only from flocks or herds that have been tested for disease (ideally multiple times). Take a close look at the herd and check the body condition of all adult animals.
If you’re buying young sheep — less than a year old — test the parents instead. Young animals are unlikely to test positive for Johann, as the bacteria are slow-growing.
2. Consider Other Livestock
It’s not just the other sheep that you need to be wary of.
Watch carefully when introducing cattle or other ruminants, especially if the animals will be grazing on or near the same pasture. Bacteria don’t mind jumping between different species.
No Volunteer to climb or borrow other people’s animals.
If you regularly bring a ram to the farm to raise new lambs, it may be wise to leave it or find an alternative. This is a surefire way to introduce OJD to your flock.
There are vaccines for OJD, however, in some places, these can be difficult to find.
When available, vaccination is a good option as it slows the shedding of bacteria from infected sheep and increases the total amount that occurs.
While it is not a definitive solution, it can help reduce mortality and control OJD if any member of the herd is infected.
It may also prevent the introduction of OJD in an unaffected herd.
Sheep are typically vaccinated as lambs between 4-16 weeks of age (which is when they are most likely to be exposed to the bacteria).
4. Other Measures
There are other steps you can take to reduce the chance of OJD, although none will increase your odds of preventing it as well as the vaccine.
If you think you have OJD, get checked out and tested immediately. If you haven’t already been vaccinated, start getting vaccinated.
Avoid feeding your sheep on the ground. Use automatic feeders or troughs to reduce their exposure to manure. Seal off low-lying areas or creeks where water may be contaminated and avoid keeping young sheep on pastures that have recently been grazed by unvaccinated animals.
Sadly, there is no cure for OJD. there is no cure. If one animal in your herd has the disease, there is nothing you can do to get rid of it.
Difficult to diagnose. In sheep, bacterial culture of feces in live animals is rarely successful in identifying OJD.
The bacteria are slow growing, taking up to 4 months to grow – a negative result does not necessarily mean that your flock is free of OJD. This may mean that the animal is in the early stages of the disease.
If you find out that a sheep in your flock has OJD, there is nothing you can do to protect it. However, you can take steps to prevent it from contaminating the rest of the herd.
Once OJD begins, you need to move your sheep to new pastures immediately. Nevertheless, there is a strong possibility that a person who tests negative may later test positive for OJD. The bacteria spread easily through manure, contaminated waterways, and nits. It can survive for so many months that it is difficult to eradicate it completely.
It’s safe to say that if one sheep has OJD, the rest have too. In some cases, it makes the most sense to humanely slaughter any sheep showing signs of OJD.
Is OJD fatal?
The saddest part of OJD is that by the time you start noticing deaths and can confirm them to be from OJD, the disease is probably already well established and it’s time to get things under control. It will take years.
While you’re waiting for the bacteria to die back in the soil, clean up the contaminated pasture.
You can do this by re-seeding, rotating with other crops, or grazing with lambs that are going straight to slaughter.
OJD is not harmful to humans – but for sheep, it is almost always fatal.
Avoid it by following the tips above—and hopefully, this rare disease remains unheard of in your flock.