Each year we work to educate our cattle clients about Pestivirus and the effect it can have in cattle herds. Vet Gabrielle Knight revisits this sometimes complex topic and reminds us why monitoring is so important.
What is pestivirus?
Pestivirus is a nasty disease that has the potential to cause some disastrous effects within your herd, including;
- Poor conception rates
- Abortions
- Congenital calf abnormalities (birth defects)
- Production of persistently infected animals
- Respiratory disease
- Increased rates of other disease
Infected animals may be transiently infected (have the disease for a short period and recover) or persistently infected (PI) meaning they remain carriers of the disease for life.
How is it spread?
Pestivirus is spread between animals in close contact, (primarily nose-nose) in areas of high density stocking (e.g. yarding, transport). Most bodily fluids can spread the disease (milk, urine, faeces, nasal secretions, foetal fluids, blood and semen).
Diagnosis
There are a number of diagnostic tests available for pestivirus. Samples include blood (serum), skin or hair. They may be performed individually or on pooled samples from numerous animals. We can determine the type of testing based on the aim of your investigation, your production system, herd management, biosecurity measures, cost and herd size.
Recognising a PI calf
Persistently infected calves can often be recognised as stunted, scruffy animals. They have a general ill-thrifty appearance and are susceptible to other infections. Rarely, these animals survive past 2 years of age. If you suspect a PI calf and are concerned about a pestivirus outbreak, please contact our clinic for testing.
What can you do if your herd is infected?
Ultimately the action plan will be determined in consultation with our vets. The options available include;
1. Do nothing and allow the disease to run a natural course
- Can be risky as transmission is unpredictable and often incomplete
2. Use PI calves for auto-vaccination
- Running a PI calf with small groups in yards can increase the rate of transmission
- This should be conducted well before joining to minimise the risk of reproductive side effects of infection
3. Establish a closed herd - Maintain thorough biosecurity and management practices to reduce the risk of introducing pestivirus
- Test all animals to detect and eliminate PI animals
- This option is risky on its own as it generates a naive herd
- Generally it is conducted in conjunction with a vaccination program
4. Implement a herd vaccination scheme
- Complete - all heifers, cows and bulls vaccinated annually
- Partial - only bulls and replacement heifers vaccinated
Conclusion
Pestivirus is a complicated disease process that has the potential to cause severe economic impacts (up to 25% losses) to your herd if it is not managed appropriately. As mention above, there are numerous options for management that can be tailored to suit your management practices. The best way to determine your herd’s pestivirus status is to consult with one of our vets for herd screening. Once the disease prevalence has been established they will be able to assist you in determining the best management protocol for your system.
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