The most common strains in cattle in New Zealand are S. Typhimurium, S. Bovismorbificans (primarily affect the gut) and S. Brandenburg (primarily causes abortions. In Spring 2025, outbreaks due to these serotypes were frequently seen on both islands with S. Brandenburg, historically a South Island disease, becoming endemic in Taranaki. In 2025, MPI reported the most cases in cattle in NZ ever (See Figure 1 below).
S. Bovismorbificans tends to cause higher death rates during outbreaks than S. Typhimurium. There is also an emerging strain - S. Give, only identified in New Zealand since 2019. This has now been found in most regions. The disease is usually spread through ingestion of infected faeces or aborted material.
Generally, cows will be depressed, go off their milk and have poor appetites, and they often have foul smelling, khaki green diarrhoea. In the case of S. Brandenburg, cows often abort, have retained membranes and are also very sick.
On average, it is estimated that 9% of the herd are carrier animals at any time. Carrier animals can shed Salmonella for months or even years in the faeces. Salmonella bacteria can survive in the environment for a long period of time (e.g. months to years in ideal conditions like wet paddocks, effluent ponds, or dry, shaded areas such as cattle or sheep yards). Conversely, it can be killed on hard surfaces in days with freezing or heating.
In a 500-milking cow herd, with 10% sick and 2% deaths, the direct costs through dead cows and loss of milk can be over $30,000 in a single season. This is not counting the milk out of supply, risk to humans, or impact on future production and reproduction. This far outweighs the cost of preventative vaccination for the herd.
Risk factors for Salmonella outbreaks in dairy cows include
Stress is almost always involved; hence we often see cases soon after dry off or around calving.
As well as avoiding the risk factors above, isolate sick animals, remove and bury aborted material, discard milk from scouring cows; and avoid grazing at-risk groups of animals on effluent paddocks. Vaccination of cattle with Salvexin®+B* (preventatively or in an outbreak) is recommended. This has been proven to reduce shedding, reduce incidence of clinical cases and reduce stock losses during outbreaks. An ideal time for herd vaccination is in late lactation. Chat to your vet about fitting a vaccination programme into your animal health plan.
For more information about Salvexin - https://www.msd-animal-health.co.nz/products/salvexinb/
For more support - https://www.sheepvax.co.nz/salvexinb-2/
*AVAILABLE ONLY UNDER VETERINARY AUTHORISATION. ACVM No: A7866. Schering-Plough Animal Health Ltd. Ph: 0800 800543. www.msd-animal-health.co.nz © 2026 Merck & Co., Inc., Rahway, NJ, USA and its affiliates. All rights reserved. NZ-SAL-260300002
