Late autumn salmonella
May 2024

It was typical day in May, very overcast and foggy conditions and I was called to check out a sick cow. She was a Friesian Jersey cross bred cow, 5 years old and recently dried off. She had suddenly started scouring the previous day. The faeces were very loose, a light green colour with some blood present. The temperature was normal at 38.6C and the heart rate was elevated to 80 beats/min. The cow appeared to be fully hydrated despite the acute scour. All the other herd members appeared to be healthy and unaffected.

A faecal sample was taken for salmonella culture and a blood sample was collected for Johnes disease testing. The cow was also confirmed as pregnant from rectal examination.

Treatment was started with an injectable antibiotic and Ketomax an anti-inflammatory drug. Oral fluid therapy is often given to suspect salmonella cows but was not required in this case.

An unusual Salmonella species was cultured at the animal health laboratory which was then sent to the ESR Wallaceville lab for salmonella serotyping. The Johnes blood test result was negative. Ten days after the faecal sample being collected the salmonella bacteria was fully identified as Salmonella Give. This is a relatively new salmonella serotype in New Zealand cattle that has increased in the numbers of affected herds in the last few years. In other herds that have had Salmonella Give, the bacteria causes scouring cows and also abortions in some cows. Salmonella Give can also result in scouring, septicaemia and death in young calves.

The dairy farmer was reminded that Salmonella is a zoonotic disease and can affect people with acute vomiting, diarrhoea, abdominal cramps and septicaemia.  In salmonella outbreaks we advise that gloves and PPE are worm by all farm staff and hands are carefully washed and cleaned prior to eating or drinking. Salmonella is also excreted by infected animals in the milk, so raw milk from the vat should not be consumed by any farm staff. Health & safety notices should also be displayed in the shed advising on the salmonella risk to people and that no eating or drinking is allowed in the shed.

Farms affected with salmonella are requested to notify their milk and meat supply companies to enable these organisations to take food safety precautions.

Advice was also given on removing any aborted material from yards and paddocks should any cows abort.

Salmonella vaccination provides good protection against the specific salmonella serotypes of Bovis-morbificans, Typhimurium, Hindmarsh & Brandenburg. There may be minor cross protection from these serotypes to Salmonella Give. The farmer decided to go ahead and vaccinate the herd for salmonella. All the cows and heifers were given two vaccinations 4 weeks apart.

The affected cow made a full recovery and no further cases of salmonella occurred in the herd which was an unusual outcome, however vet and farmer were both very grateful and relieved!