Pestivirus is an insidious disease that is endemic in both the beef and dairy herds of Australia. It’s estimated that up to 90% of herds have been infected, according to a report in the Australian Veterinary Journal.

While the disease is relatively easy to diagnose due to highly accurate testing, evaluating its impact and potential risk to a herd can be difficult, says Zoetis livestock operations manager, Dr Matthew Petersen. This is supported by several published studies.

What is well known about the disease?

The most well-known aspect of the disease is its reduction in reproductive efficiency. The virus is frequently involved in poor pregnancy testing results, increased abortion rates and the birth of persistently infected calves.

A New Zealand trial showed that these persistently infected (PI) cattle go on to produce around half the milk volume and milk solids as their non-PI herd mates, according to a study by Voges et al, published in Vetscript, September 2006.

What’s underestimated about the disease?

The aspect which is often overlooked by many producers is the ability of pestivirus to cause profound immune suppression in cattle. This immune suppression results in exacerbated levels of disease and mortality in various parts of the supply chain.

Persistently infected (PI) cattle carry a huge production threat to herds. 

For example:

• In NZ, a trial by Bates, A., et al published in Vet Record, 2019, showed that dairy calves which co-existed with a pestivirus infection (PI) had a 6.4x increase in scouring between 3–35 days of age and a 3.4x greater likelihood of dying in the first 2 days of life
• In the National Bovine Respiratory Disease Initiative which evaluated risk factors for BRD in Australian feedlot cattle from 2009 to 2011, cattle exposed to pestivirus had their risk of BRD increased 1.7 times, according to a report published in Preventative Veterinary Medicine, 2016.

What’s the end outcome for dairy producers?

Dr Petersen said as pestivirus cycles in the herd its impact can present in different ways. The most impactful events include:

• Lower pregnancy rates

• Disrupted and delayed calving, increasing calving spread

• Higher calf losses from joining to weaning, especially in heifers or first calvers

• Higher levels of disease in calves including calf scours, pinkeye and pneumonia/pleurisy

• Post weaning losses due to ill thrift and mortality

• Lower than expected growth rates in some cattle – an obvious tail in the mob.

Simple and effective protection

“Vaccinating cattle with Pestigard is the easiest and most effective way to protect your herds against the impacts of pestivirus,” Dr Petersen said.

“A vaccination program for a herd starts with a 2-dose heifer treatment up to six months apart simply followed with annual boosters on bulls, cows and any other animal retained on farm for over 12 months post previous vaccination.

“Initial vaccination of breeding animals must be completed prior to joining to achieve the optimal outcomes from vaccination.”