A new study uses the British Geological Survey’s geochemical map

to investigate whether minerals in the environment are a factor in

this predominantly fatal neurodegenerative disease of horse

Fordyce, F.M.

Lilly, A.

McGorum, B.C.

Shaw, D.J.

Wylie, C.E.

English

NERC Open Research Archive

Newsletter 72 • Autumn 2011 ecrrMembers’ reportsBritish Geological Survey3EQUINE GRASS SICKNESS was firstrecorded in army horses at Barry Camp,Angus, in the early 1900s after whichoutbreaks were described acrossnortheast Scotland before spreading toEngland and Wales. Great Britaincontinues to have the highest reportedprevalence worldwide, with a highproportion of cases in Scotland.The common clinical signs relate togastrointestinal paralysis and includeabdominal pain, difficulty swallowingand weight loss. The precise causeremains unknown, but there isevidence to suggest that it may be atoxico-infectious form of botulism, withClostridium botulinum producingneurotoxins locally within thegastrointestinal tract. Certain ‘trigger factors’ may alsobe required to induce disease. Theseremain largely unidentified, but there isstrong evidence implicating anenvironmental agent encountered whilegrazing, and low dietary intake ofessential elements has beenpostulated as a risk factor.The Royal (Dick) School ofVeterinary Studies (RDSVS), the BritishGeological Survey (BGS) and theJames Hutton Institute (JHI) havecollaborated to investigate thepotential association betweengeochemical parameters in thesoil/environment and the distribution ofEGS cases in eastern Scotland. Thisinvestigation was conducted as aretrospective case-control study usingdata collected between 01/01/1990 The association between the distribution of cases ofequine grass sickness in Eastern Scotland andenvironmental geochemical parametersWylie C.E.1, Shaw D.J.2, Fordyce F.M.3, Lilly, A.4and McGorum B.C.2(1) Animal Health Trust, Lanwades Park, Kentford,Newmarket, Suffolk CB8 7UU, UK(2) Royal (Dick) School of Veterinary Studies & The Roslin Institute, Easter Bush Veterinary Centre, The University of Edinburgh, Roslin EH25 9RG, UK(3) British Geological Survey, West Mains Road,Edinburgh EH9 3LA, UK(4) James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, UKA pony exhibiting the classical clinicalsigns of equine grass sickness withsevere weight loss, a ‘tucked-up’abdominal appearance, ‘elephant-on-a-tub’ stance and depressionPhoto: Professor Bruce McGorum (RDSVS)and 01/06/2006. A case wasdetermined to be any horse or ponydiagnosed with EGS by a clinician atthe RDSVS. Two time-matchedcontrols were obtained for each case,and a complete spatially referenceddatabase of locations was producedfor 455 cases. This involved 1365animals in total – the largest case-control study of EGS undertaken todate (see map).A range of trace elements, mostwith known biological function, wascollated from two geochemicaldatasets. Interpolated maps (based ona 250 m grid) of fine fraction (< 150µm) first and second order streamsediment total element concentrationswere provided by the BGSGeochemical Baseline Survey of theEnvironment (G-BASE) project, whichis the national geochemical survey ofthe UK. The James Hutton Institute(JHI), formerly, the Macaulay Land UseResearch Institute, also provided mapsof averaged values of a range of traceelements determined by InductivelyCoupled Plasma – Atomic EmissionSpectrometry or Graphite FurnaceAtomic Absorption Spectrometry froma wide range of individual soil profilescollected from throughout Scotland.Statistically significant univariateassociations were found for a numberof geochemical parameters in bothdatasets. For example, lowerconcentrations of chromium, lead andzinc in the BGS stream sedimentdataset (P<0.003) and the JHI soildataset (P<0.001), and higherconcentrations of titanium in the BGSsediment dataset (P<0.003) and JHIsoil dataset (P<0.001) were associatedwith an increased risk of EGS.Further analysis is ongoing toestablish a final multivariable model todetermine which factors remainassociated with EGS occurrence afteraccounting for other variables. It ishoped this study will identifygeochemical parameters in soils thatwarrant further investigation at the levelof the horse-grass-soil relationship.Published by permission of the directorof the British Geological Survey.Map showing the location of the equine grass sickness cases(n=455) and controls (n=910) in eastern Scotland andconcentrations of zinc in the environment based on the BGS G-BASE stream sediment dataset for Scotland. Map source: 2001 Census Output Area Boundaries. Crown copyright 2003, reproduced with the permission of theController of HMSO. Geochemical data © BGS, NERCEquine grass sickness – the geochemical connectionA new study uses the British Geological Survey’s geochemical mapto investigate whether minerals in the environment are a factor in this predominantly fatal neurodegenerative disease of horses 

Equine grass sickness : the geochemical connection

http://nora.nerc.ac.uk/17269/1/ecrr-news72-1_3.pdf

Equine grass sickness : the geochemical connection

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