MCF is a significant and frequently fatal disease of deer in New Zealand. Caused by a herpesvirus that is “sheep-associated”, MCF is a common but sporadic disease Occurrence is often on an individual basis and while outbreaks occur, they are rare.
There is a seasonal incidence which peaks in winter. It is more common in the South Island. There are differences in breed susceptibility. Pere David and Sika are the most susceptible followed by Wapiti then red deer.
In the early days of deer farming (1979 to 1985) it was considered the most important disease of farmed deer. Since 1985 there has been a steady decline in the number of diagnosed cases.
It has been recorded in deer under two years old, but it normally affects adult deer particularly red stags or Wapiti bulls.
What are the signs?
It occurs in two forms:
- Acute - depression, inappetence, fever and diarrhoea. It rapidly progresses over the course of 1 or 2 days to severe bloody diarrhoea and death. Often the first sign the farmer sees is finding the animal dead.
- Chronic - presents as a central nervous system disease with ocular and nasal discharges, corneal opacity, crusting around the nose and anus. Chronically affected animals tend to lose weight and succumb in days to a few weeks.
How does it spread?
Caused by a herpesvirus that is “sheep-associated”. Sheep are asymptomatic carriers but when put under pressure tend to shed the virus e.g. late pregnancy and lactation.
It does not spread from deer to deer.
Diagnosis
Clinical signs and histopathology can be used to diagnose the disease. The virus causes a massive vascular incident with vasculitis throughout the body. Gross findings at postmortem examination are usually not significant although sometimes petechial haemorrhages can be seen in various tissues. Histological changes in the brain are considered the best diagnostic indicator. There is a PCR test available for ante-mortem testing on EDTA blood samples.
Treatment and prevention
Contact with sheep at times they are under stress should be avoided.
There is no treatment. Once signs are seen (acute or chronic) the disease is fatal.
