Sudden deaths in sheep as a result of clostridial bacteria can prove to be extremely difficult to diagnose as a sheep farmer near Brecon recently found

Sudden ewe deaths in the run-up to lambing can often be attributed to sheep fulfilling their lifelong ambition of dying, but for a Welsh farming partnership there was a logical explanation.

John and Mary Probert have been running an 800 strong flock of sheep in the Honddu Valley, Brecon, mid-Wales, for the past 40 years. But a few years ago they started to lose them to a mysterious disease which caused their animals to die suddenly and unexpectedly in the run-up to lambing.

Sudden deaths started occurring at Baily Brith Farm about eight years ago. At first Mr Probert thought these deaths were just a part of everyday sheep farming. But as the years went by, more and more ewes were dying.

“We tried everything” he says. “We got our vet involved as soon as we could, but despite sending several sheep to the VI Centre in Carmarthen for autopsy, nobody could give us a conclusive reason for the mysterious deaths.”

A thorough investigation involving soil sampling, faeces testing, water sampling and blood tests revealed lots of bacteria, but no definitive answer. Leaving a rather limited choice of treatment options.

“Sheep that appear fit and well in the morning can be found dead later that day. The first thing you notice is the awful smell, even when the animal is still alive. The animal will suddenly go off its food and start to blow up. It all happens within a few hours and I have even seen sheep keel over and die as I’ve walked towards them.”

An 8-strain vaccine was already being used to protect the flock against clostridial diseases, but this was having little effect. In one year alone the Proberts lost 30 twin-bearing ewes just a few weeks before lambing. It always seemed to be ewes in the best condition carrying twins that died suddenly.

The solution came after reading about a beef farmer who had lost three in-calf cows as a result of an infection caused by the C sordellii strain of clostridia bacteria. “It turned out that the strain of bacteria that was giving us so much trouble wasn’t covered by the original 8-strain vaccine,” says Mrs Probert.

Vaccination using a new 10-strain medicine, which does provide protection against C sordellii started immediately and the following year only one ewe was lost in the run-up to lambing.

Schering Plough Animal Health vet Paul Williams says there are at least 10 serious clostridial bacteria that can cause sudden deaths in livestock. “These bacteria share the same environment as sheep and cattle and are ever-present in soil, on pasture, within buildings and even in the tissues and organs of animals.

“For much of the time, the bacteria remain dormant. However, when trigger factors such as injury, bruising and stress stimulate the bacteria to multiply, toxins are released in large quantities.” The toxins then attack the muscles, gut and liver, leading to severe disease and ultimately death, he adds.

“The quick onset of these diseases means that intensive treatment using antibiotics is rarely effective. However, protection can be achieved by using a broad-spectrum vaccine to provide animals with the necessary antibodies to combat all strains of the lethal toxins.”