Hundreds of sheep in Otago and Southland have died following an outbreak of salmonella and a vet says the problem could get worse.
The bacteria causes pregnant ewes to abort their foetuses and may cause the death of the ewe.
The strain, Salmonella Brandenburg, can be transferred to humans although the Southern District Health Board says reported salmonella levels in humans are not of concern at this point.
Clutha Vets veterinarian John Smart says about 30 farms are affected in the Balclutha area and he knows of others further south.
He says many farmers never report salmonella so the problem could be bigger than the 1000 or so sheep he knows of that have died.
Mr Smart says there could more cases once lambing gets underway fully next month.
He says until lambing has finished it's very hard to know just how many sheep have been affected but it appears the region is experiencing a growing number of cases - after a long lull.
Mr Smart says there is a vaccine farmers can use but it's far from fully effective.
He says there are a range of practical measures farmers can and should take if their mobs are affected:
- Spread the ewes out to reduce the risk of the disease spreading through the population pressure.
- Aborted foetuses should be disposed of straight away as hawks and seagulls can spread the disease to other farms in the locality.
- Isolate sick ewes that have aborted put them in a paddock by themselves.
- Treat then with antibiotics, but not penicillin which is ineffective.