Abstracts � Vol 30, No 2 (2010) 115

Recent evidence has suggested that exercise decreases insu-lin resistance in obese horses; this laminitis treatment isunique because exercise is prescribed before complete re-covery if certain criteria are met. The success of this systemmay be dependent on owner compliance with diet and ex-ercise recommendations.

CLINICAL RELEVANCEThis treatment method may provide an effective method ofrestoring soundness and normal hoof anatomy in certainpopulations of laminitic horses. In this small population,hoof health was restored without surgical techniques.

CONCLUSIONFurther investigation with more cases is warranted.

Neutrophil Gelatinase-AssociatedLipocalin and MatrixMetalloproteinases in Laminar TissueFrom Horses Subjected to IntestinalObstruction and Treated WithHydrocortisoneLuciane M. Laskoski, MSc, Carlos A.A. Valadao, DVM,Rosemeire O. Vasconcelos, DVM, RafaelResende Faleiros, DVM, Danilo Ferrucci, MSc, JulieteA.F. Silva, MSc, and Dagmar R.S. Machado, DVM,Department of Veterinary Surgery and Medicine(Laskoski, Valadao) and Department of VeterinaryPathology - FCAV- Sao Paulo State University,Jaboticabal, SP 14884-900, Brazil (Vasconcelos);Department of Veterinary Clinics and Surgery, School ofVeterinary – Federal University of Minas Gerais, BeloHorizonte, MG, 30123-970, Brazil (Faleiros);Department of Applied Immunology - University ofCampinas, Campinas, SP 13484-370, Brazil (Ferrucci,Silva, Machado)

TAKE HOME MESSAGEHydrocortisone treatment may be beneficial to reduce therisk of laminitis in horses subjected to intestinal surgery.

INTRODUCTIONLaminitis is a major complication of gastrointestinal dis-eases in horses and its physiopathology is connected withlamellar basement membrane degradation by matrix metal-loproteinases (MMPs) and leukocyte infiltration. The ob-jective was to study laminar MMP-2, MMP-9 and NGALexpression in horses subjected to jejunal obstructiontreated or not with hydrocortisone.

MATERIAL AND METHODSZymography was performed to quantify MMP-2, MMP-9and NGAL in laminar tissue samples obtained from horsesallotted in the control group (CG, n¼ 7); the sham-oper-ated group (SG, n¼ 5, jejunal enterotomy); the non-treated group (NTG, n¼ 5, jejunal obstruction), and thetreated group (TG, n¼ 4, jejunal obstruction and hydro-cortisone4mg/kg, IV). Calprotectin expression was usedto confirm neutrophil laminar presence in obstructedgroups. Data was analyzed by one way ANOVA followedby Tukey post-hoc test (P < 0.05).

RESULTSOverexpression of MMP-2 and MMP-9 occurred in ob-structed groups (NTG and GT) when compared to CGhorses. NGAL/MMP-9 complex expression was increasedin the SG and NTG horses, but no increase was observed inhorses treated with hydrocortisone (TG). Leukocyte pres-ence in obstructed groups was detected by immunohisto-chemistry.

DISCUSSIONAmplifying previous findings that equine intestinal ob-struction can cause lung neutrophil accumulation, ourstudy indicates that jejunal obstruction may produce neu-trophil accumulation and MMP overexpression in equinelaminae and that hydrocortisone can ameliorate laminarinflammation.

CLINICAL RELEVANCEHydrocortisone treatment may ameliorate laminar inflam-mation in horses subjected to intestinal surgery.

CONCLUSIONIntestinal obstruction can induce laminar MMP expressionand inflammation.

Leukocyte Infiltration and the Roleof Interleukin-6 During theDevelopment of Oligofructose InducedLaminitisMichelle B. Visser and Christopher C. Pollitt, AustralianEquine Laminitis Research Unit, School of VeterinaryScience, The University of Queensland, Brisbane,Australia

TAKE HOME MESSAGEThe leukocytic infiltration of carbohydrate induced lamini-tis is preceded by IL-6 expression.

116 Abstracts � Vol 30, No 2 (2010)

INTRODUCTIONIncreased inflammatory cytokine expression (especially IL-6) and infiltration of leukocytes into the lamellar tissue oc-curs during black walnut extract and other inductionmodels of laminitis. We investigated a role for IL-6 duringoligofructose induced laminitis.

MATERIALS AND METHODSLaminitis was induced in normal horses (n¼ 5) by alimen-tary oligofructose dosing. Lamellar biopsies were collectedpost induction. Histological and immunohistochemicalanalysis for calprotectin and real time PCR for IL-6 expres-sion was performed. The effect of recombinant IL-6 onMMP expression and tissue histology in lamellar explantsand equine keratinocyte cultures were analyzed by gelatinzymography.

RESULTSCalprotectin positive monocytes and neutrophils were ob-served 18 hours post dosing, initially perivascular but laterintra-dermal. Lamellar epidermal cell cytoplasm calprotec-tin reactivity occurred between 24 to 48 hours. Signifi-cantly increased IL-6 gene expression occurred at12 hours. Exposure to IL-6 increased pro MMP-9 inlamellar explants but not in equine keratinocytes.

DISCUSSIONThe leukocytic infiltration of oligofructose induced lamini-tis is preceded by IL-6 expression. IL-6 did not activateMMP or cause degradation of the lamellar BM compo-nents in vitro. The outcome of IL-6 signalling in laminitisis unclear.

CLINICAL RELEVANCEPreventing cytokine expression and leukocyte infiltrationduring laminitis development may ameliorate its severity.

CONCLUSIONLeukocyte infiltration may be a reaction to, rather thana cause of, lamellar pathology.

Histopathology of Equine Hoof Wall,Skin and Chestnut in AcuteSpontaneous LaminitisOve Wattle and Elin Hansson, Department of LargeAnimal Clinical Sciences, Faculty of VeterinaryMedicine, University of Agricultural Sciences, Box7018, S-750 07 Uppsala, Sweden

TAKE HOME MESSAGEThe living cells of the lamellae are not the only epidermalcells affected in acute laminitis.

INTRODUCTIONObel (1948) proposed that the pathological changes ob-served in laminitis are a result of a primary disturbance ofthe metabolism and differentiation of the keratinising epi-dermal cells. It is reasonable to believe that other epidermalbasal and supra basal cells than those under the influence ofthe body weight might respond to the possible causativefactor(s) of laminitis.

MATERIALS AND METHODSSkin, chestnut, hoof wall strata externum, medium, andinternum biopsies from 10 horses with spontaneousacute laminitis were taken within 48 hours after first clin-ical signs of lameness and from 9 control horses. H&E,PAS and periodic acid silver methanamine stained sec-tions were blinded before examination under light mi-croscope. A number of characteristics related to acutelaminitis were subjectively scored using a scale rangingfrom 0 to 3: white blood cells in blood vessels, whiteblood cells in tissue, hyperemia, hemorrhage, intra cellu-lar edema, basement membrane detachment, basal cellshape, necrosis, number of suprabasal cell layers and,basal cell chromatin density, number of basophilic kera-tohyalin granules in skin, chestnut and periople, and instratum internum - stretched lamellae. Kruskal-Wallistest on a rounded mean score was used to analyzewhether the distribution of histological scores differedbetween groups.

RESULTSIn horses with laminitis, basal cells had a more cuboidalshape with more rounded cell nuclei and a more coarselymeshed chromatin network in all tissues but the skin.Changes in the basement membrane, such as failure toremain attached to the basal cells, were only noted inthe laminar layer and a decrease in the number of kerato-hyalin granules were only seen in the chestnut andperiople.

DISCUSSION AND CLINICAL RELEVANCEOther epidermal tissues than the laminar layer is affected inacute laminitis. It is the unique mechanical forces imposedon the laminar epithelium that makes the disease moreobvious in the hoof.