Yersiniosis is a contagious bacterial infection found in the gut which can cause ulceration and abscesses in the gut wall.
Signs of infection include diarrhoea, lack of energy, an unwillingness to eat, a rough coat and often rapid weight loss.
The disease can be seen in a single animal or in many animals within a mob. Left untreated, death can occur within days of the first symptoms.
“Anyone who suspects they have yersiniosis should talk to their vet straight away,” DairyNZ animal husbandry extension specialist for Southland Anna Irwin said.
“It takes several days to get confirmation of the disease in the lab but in the meantime your vet can work through a plan to treat the symptoms and minimise the impact.”
She said the disease usually affected young animals and any ruminant, especially weaned lambs and deer, could get it by grazing the same pasture after affected calves. Dogs and wild animals such as pigs, birds, including ducks and chickens, and rodents also spread strains of the disease.
“So it’s important for dairy graziers to know about yersiniosis, especially if they are also trying to fatten other young stock on their farm as well,” Irwin said.
“Lambs and weaned deer can die really quickly from it.”
She said pasture and water troughs could remain infected for up to nine months although dry weather and frost helped cleanse paddocks.
“The disease is not widely understood unless you’ve experienced it yourself so dairy farmers should be talking to their graziers if they think there could be the chance their calves are infected.”
She said the bacteria was commonly found in animals’ intestines and many could carry it without becoming ill. Older stock usually built up immunity to it.
“Young stock often get sick with yersiniosis after a stressful event such as weaning but it can be simply from yarding the animals in foul weather or trucking them to a grazier.”
She said rain, mud and cold winds all contributed as stressors for calves and Southland and Otago’s cool, wet January this year probably contributed to a number of cases.
“We also know the worm burden is high this summer and this is recognised as a predisposing factor for outbreaks of yersiniosis. It’s been wet and it’s been warm enough, believe it or not, for parasites to be present in high numbers so drenching at the right time is really important so animals are not compromised.”
However, farmers had found drenching calves with yersiniosis had made them sicker which they put down to the drench aggravating the ulcers in the gut wall. Probiotics had helped in some cases.
“There is a vaccine but it is only licensed for use in deer,” Irwin said.
“For cattle, farmers can only control the disease by minimising the predisposing factors and treating it quickly when animals come down with it.
“The important point is to look after calves well following weaning and during the next few months. Ensure they have really good nutrition and a good health programme. Avoid yarding, transporting or changing their diet in bad weather if possible. Farmers should also keep young stock mobs separate, especially on farms that also have sheep and deer.”
Calves and other young stock with yersiniosis can also become ill with a variety of other infections including coccidiosis, salmonellosis, bovine viral diarrhoea and campylobacteriosis, making the initial diagnosis difficult.
She said animals which survived were often stunted initially but with good management could recover.
