Grave fears with salmonella strain

Mystery surrounds the outbreak of a salmonella strain that veterinarians fear could devastate southern sheep farms like the brandenburg strain of the past decade.  Gribble's Lab in Invermay, near Mosgiel, identified 15 farms in Southland and Otago this year with ewes suffering from enteric salmonella, also known as salmonella hindmarsh reports The Southland Times.  Sheep died in all cases, with one Southland farmer losing 96 ewes from a flock of 2500 many of which were carrying lambs. VetSouth vet Kim Kelly, of Winton, said hindmarsh was rare in the South Island, as it typically needed the warmer North Island climate to survive. Infected sheep were lethargic, had khaki-coloured diarrhoea, suffered severe damage to their gut lining and died in most cases, Mrs Kelly said. VetSouth vets originally attributed the outbreak to a decline in Salvexin+B vaccinations, which protect ewes against abortions and deaths in late pregnancy caused by salmonella brandenburg, but also cover hindmarsh, she said. VetSouth figures show Salvexin+B vaccinations have dropped from about 390,000 in 2001 to about 80,000 this year but Mrs Kelly said only five cases of brandenburg had been reported in Southland this year, which suggested the vaccine was doing its job. Even more puzzling was that hindmarsh typically appeared in ewes under stress but the cases reported this year were ewes in good condition, that had not been yarded and were on good planes of nutrition, she said.  That left VetSouth vets with no clue as to what caused the disease or what kind of comeback it might make when warmer temperatures reappeared in January, she said.