Johne’s Disease – Is it worth worrying about in deer

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What is it?

Johne’s disease is an incurable bacterial disease that affects the intestines of ruminants. It causes the intestinal wall to slowly thicken reducing absorption of nutrients. Animals develop watery diarrhoea and loose condition. Affected animals don’t respond to treatment with drench and antibiotics, there is no cure, and they will almost certainly die.

What does it look like in deer?

Typically, we see Johnes in two distinct forms:

  • Major outbreaks in young deer.

  • Sporadic cases in mature deer

Major outbreaks in weaner and yearling deer

This typically occurs in the first winter and spring in deer as young as 8 months. Up to a quarter of the mob may be affected.

Weaners fail to thrive, develop diarrhoea, and characteristically have a green scour down the hindquarters and hocks. They rapidly loose condition, have a patchy light coat, and may waste away over just a few weeks.

Parasitism and Yersinia can look similar in appearance but will respond to drenching or antibiotic treatment.

Sporadic cases in mixed age deer

This is normally seen as the odd skinny hind with green stained hocks due to a continuous or intermittent scour. I have occasionally seen stags with Johnes in velveting herds.

These hinds will spread infection to the fawns via in utero spread or via the faeces soon after fawning. It is important that hinds with Johnes are culled before fawning kicks off.

Can much be done about Johnes?

The answer is yes – Johne’s carriers can be identified via blood testing and culled.

A Johnes control programme can look as follows:

YEAR 1

  • Blood test all breeding females over 1 year of age prior to fawning, normally this is done in July-Oct. It is important to cull pregnant hinds with visible signs of Johnes or high antibody levels on the blood test before fawning.

  • Blood test all sire stags and velvet stags greater than 1 year of age around button drop (Aug-Sept)

YEAR 2 AND ONWARDS

  • Blood test all pregnant replacement R2 hinds and replacement velvet spikers in July-Oct.

Talk to me if your concerned about Johnes in your deer herd and want to do something about it.