October Vet’s Diary with Dr Matthew Balfour BVM&S MRCVS
Across the business in Northern England and Scotland we’ve had numerous submissions now for total worm count and worm egg count samples for grouse. We’ve also had lots of blood samples come through for louping ill antibody testing.
In terms of the results for both, it’s been very varied. Some birds are practically clear of louping ill and we’re only getting the very odd positive case. Other moors have been up to 50% positive.
What that means is that at least half of those grouse at some point in their lives have been exposed to the louping ill virus and what’s particularly worrying is that we know that louping ill kills over 70% of grouse chicks. So, if we find three grouse chicks that are positive for louping ill antibodies, there are probably another seven that we aren’t finding and testing because they have probably already died. This can go a long way in explaining the reductions of numbers on grouse moors.
Louping ill is spread by ticks and control of the disease relies on reducing tick numbers on the moor using sheep as a tick ‘mop’. There used to be a vaccine which aided in this, however unfortunately it is no longer on the market. Tick control now relies on placing a sheep flock on the moor and using regular acaricide treatments to mop up and kill ticks. Over time this should reduce the tick population and subsequently louping ill levels.
In terms of worm count, an average T.tenius Total Worm Count above 3,000 is considered to be of clinical significance on a moor. On moors that are relatively well controlled, there will be only a handful of worms per bird. Grouse are more likely to be affected by T.tenius worms if they are in poor condition with poor food availability, have concurrent disease issues (eg high tick burden), or are exposed to a high environmental challenges (i.e. high density of birds in the same area, high levels of worm eggs in the ground). However, if medicated grit is administered properly, the grouse have plenty of food available, and disease is being controlled, the worm counts will be reduced.
Cryptosporidiosis, the cause of ‘Bulgy Eye’ in grouse, was first diagnosed around 2010 and we are pleased to report we have only seen a couple of cases of this disease so far this year.
On certain moors, we are seeing Heather Beetle which is disrupting the food supply. It may be geographic and estate specific – we are seeing more of it in the North East of Scotland – but where it is present and is reducing the availability of heather, disease and poor grouse counts are apparent.
With these factors in mind, good moorland management and disease control must be administered for grouse. We would encourage gamekeepers to make sure plenty of feed is available and well distributed for the birds. There also needs to be an adequate supply of grit. The grit needs to be medicated, only used during the closed season, and refreshed regularly.
We would also encourage gamekeepers to continue submitting bids for TWC’s, cocci counts, louping ill testing, and cryptosporidiosis testing in order to take a proactive approach and so issues can be identified at the earliest opportunity. We are then able to provide veterinary advice and recommendations for the health and welfare of the grouse.
Originally written for October’s monthly feature of Countryman’s Weekly – ‘The Vet Diaries’
