Earlier this year, our veterinary team was called out to a Waikato dairy farm after a group of cows broke into a stack of mouldy maize. A few days later, several cows began showing signs of illness, prompting an urgent on-farm visit.
One cow was found down in the paddock, displaying concerning symptoms:
We immediately administered supportive care, including:
Meanwhile, other affected cows remained standing but presented with:
Given the recent maize consumption, rumen acidosis was a primary suspect. However, we also considered:
To confirm the diagnosis, we collected faecal samples for laboratory testing.
Both rumen acidosis and Salmonella can cause foul-smelling diarrhoea. However, there are key differences:
Regardless of the cause, fluid therapy with electrolytes is essential to replace losses and support recovery.
Lab cultures confirmed the presence of Salmonella. Interestingly, the strain identified in this outbreak was Salmonella Give, while the previous outbreak had been caused by Salmonella Typhimurium. This indicated two separate outbreaks, not a continuation of the same infection.
Given the recurrence, we recommended vaccinating the herd. Although the vaccine does not currently include the Salmonella Give strain, which is relatively new, there may be some cross-protection. Vaccination during an outbreak is still considered beneficial to limit spread and protect unaffected animals.
To reduce the risk of Salmonella outbreaks in your herd:
This case highlights the importance of early intervention, accurate diagnosis, and proactive prevention in managing herd health. If you suspect a Salmonella outbreak or have concerns about feed safety, contact our veterinary team immediately.
