Evidence for vascular and enzymatic events in the pathophysiology of acute laminitis: which pathway is responsible for initiation of this process in horses?

Post-mortem Computed Tomographic Angiography in Equine Distal Forelimbs: A Feasibility Study

In-depth understanding of pathophysiological processes occurring in the vasculature of the equine distal limb is of great importance to improve both diagnostic and therapeutic approaches to diseases. To gain further insights, a model allowing high-resolution 3D-visualization of the vasculature is necessary. This pilot study evaluated the feasibility of restoring vascular perfusion in frozen-thawed distal equine cadaver limbs without prior preparation using computer tomographic imaging (CT). Five frozen-thawed, radiographically normal forelimbs were perfused with a lipophilic contrast agent through the median artery and radial vein in three phases (arterial, venous, and arterial-venous combined (AVC) dynamic). For comparison, one additional limb was perfused with a hydrosoluble contrast agent. The CT-studies (16-slice MDCT, 140 kV, 200 mA, 2 mm slice thickness, 1 mm increment, pitch 0.688) were evaluated at 11 specified regions for visualization of the vasculature and presence of artifacts or anatomic variations. The protocol used in this study proved to be feasible and provided good visualization (93.1%) of vasculature with low rates of artifacts. During the different phases, vascular visualization was similar, but while filling defects decreased in the later phases, extravasation worsened in the 2 limbs where it was observed. Subjectively, the best quality of angiographic images was achieved during the AVC dynamic phase. Perfusion with hydrosoluble contrast resulted in significantly lower vascular visualization (74.0%) and higher artifact rates. This study shows that reperfusion of frozen-thawed equine distal limbs with a lipophilic contrast agent allows for high-quality 3D-visualization of the vasculature and may serve as a model for in situ vascular evaluation in the future.

Ergogenic effects of phosphatidylserine alone and combined with branched-chain amino acids in trained rats

Acute phosphatidylserine (PS) or branched-chain amino acids (BCAA) supplements alone may have an adrenocorticotropic hormone, cortisol suppressive effect and increase the testosterone/cortisol ratio, but the associated effect of these supplements during a period of high-intensity physical stress is not yet known. The study investigated the effects of chronic PS supplementation alone and combined with BCAA during high-intensity interval training (HIIT) on training volume tolerance, anabolic-catabolic balance and stress biomarkers in rats. Thirty-three rats were separated into: placebo (PLA, n=11), PS alone (n=11) and combined with BCAA (PSBCAA, n=11). Groups performed swimming sessions of HIIT (5 series × 1 min × 1 min recovery; external load equivalent to 13% of body mass) and nine recovery sessions of moderate-intensity training (30 min at 5% of body mass) alternately. One-way ANOVA was used to compare biochemical variables and two-way ANOVA was calculated to compare training volume. Training volume performed (TVP) was higher in first, fourth, fifth, sixth, and eighth HIIT sessions in the PS group in comparison to PLA (P<0.05). TVP was higher in the fourth session in PSBCAA compared to PLA. There were no differences in TVP during the sessions between PS and BCAA groups. Creatine kinase (CK) was lower in PSBCAA in comparison to PS alone (P=0.03) and PLA (P=0.04) after the experimental period. Testosterone concentration was enhanced in PSBCAA group compared to PLA (P=0.01); testosterone/corticosterone ratio was higher in PSBCAA compared to PS (P=0.05) and PLA (P=0.004) after protocol. PS combined with BCAA increases testosterone concentration and testosterone/corticosterone ratio, demonstrating an enhancement of anabolic state in trained rats.

Pododermal angioarchitecture in the equine hoof wall: A light and scanning electron microscopic study of the wall proper

BACKGROUND

Blood supply is an important factor for the normal function of the equine hoof, but earlier studies present conflicting data on functional characteristics of its angioarchitecture.

OBJECTIVE

Emphasis was laid on demonstration of the microvascularisation in the different hoof wall regions, aiming at assessment of specialised vascular structures, e.g. vascular sphincter mechanisms and arteriovenous anastomoses.

METHODS

The angioarchitecture of the adult pododerma in the equine hoof wall was examined by scanning electron microscopy of micro-corrosion casts assisted by exemplary histological and immuno-histochemical characterisation of the pododermal vasculature.

RESULTS

The microvasculature of the lamellae and terminal papillae in all hoof wall regions was described in detail. Focal dilations and microvascular sphincters were a common feature. In contrast to former investigations, true arteriovenous anastomoses were detected at the base of the primary lamellae and the terminal papillae only, while thoroughfare channels proved a regular element within the microvasculature of the wall proper. Bicuspid venous valves were detected as regular feature. For the first time, the alpha-smooth muscle actin-reactivity of the microvascularisation in the hoof wall was systematically assessed, verifying its specialised vasomotor devices.

CONCLUSIONS

The vasculature of the hoof wall displays specific angio-adaptations to high pressure and tensile load.

Physics of animal health: on the mechano-biology of hoof growth and form

Global inequalities in economic access and agriculture productivity imply that a large number of developing countries rely on working equids for transport/agriculture/mining. Therefore, the understanding of hoof conditions/shape variations affecting equids' ability to work is still a persistent concern. To bridge this gap, using a multi-scale interdisciplinary approach, we provide a bio-physical model predicting the shape of equids' hooves as a function of physical and biological parameters. In particular, we show (i) where the hoof growth stress originates from, (ii) why the hoof growth rate is one order of magnitude higher than the proliferation rate of epithelial cells and (iii) how the soft-to-hard transformation of the epithelium is possible allowing the hoof to fulfil its function as a weight-bearing element. Finally (iv), we demonstrate that the reason for hoof misshaping is linked to the asymmetrical design of equids' feet (shorter quarters/long toe) together with the inability of the biological growth stress to compensate for such an asymmetry. Consequently, the hoof can adopt a dorsal curvature and become 'dished' overtime, which is a function of the animal's mass and the hoof growth rate. This approach allows us to discuss the potential occurrence of this multifaceted pathology in equids.

Misoprostol Inhibits Lipopolysaccharide-Induced Pro-inflammatory Cytokine Production by Equine Leukocytes

Pro-inflammatory cytokines including tumor necrosis factor α (TNFα), IL-1β, IL-6, and IL-8 are potent immune mediators that exacerbate multiple equine diseases such as sepsis and laminitis. Unfortunately, safe and effective cytokine-targeting therapies are lacking in horses; therefore, novel mechanisms of inhibiting cytokine production are critically needed. One potential mechanism for inhibiting cytokine synthesis is elevation of intracellular cyclic AMP (cAMP). In human leukocytes, intracellular cAMP production is induced by activation of E-prostanoid (EP) receptors 2 and 4. These receptors can be targeted by the EP2/4 agonist and prostaglandin E1 analog, misoprostol. Misoprostol is currently used as a gastroprotectant in horses but has not been evaluated as a cytokine-targeting therapeutic. Thus, we hypothesized that misoprostol treatment would inhibit pro-inflammatory cytokine production by lipopolysaccharide (LPS)-stimulated equine leukocytes in an in vitro inflammation model. To test this hypothesis, equine leukocyte-rich plasma (LRP) was collected from 12 healthy adult horses and used to model LPS-mediated inflammatory signaling. LRP was treated with varying concentrations of misoprostol either before (pretreated) or following (posttreated) LPS stimulation. LRP supernatants were assayed for 23 cytokines using an equine-specific multiplex bead immunoassay. Leukocytes were isolated from LRP, and leukocyte mRNA levels of four important cytokines were evaluated via RT-PCR. Statistical differences between treatments were determined using one-way RM ANOVA (Holm-Sidak post hoc testing) or Friedman's RM ANOVA on Ranks (SNK post hoc testing), where appropriate (p < 0.05, n = 3-6 horses). These studies revealed that misoprostol pre- and posttreatment inhibited LPS-induced TNFα and IL-6 protein production in equine leukocytes but had no effect on IL-8 protein. Interestingly, misoprostol pretreatment enhanced IL-1β protein synthesis following 6 h of LPS stimulation, while misoprostol posttreatment inhibited IL-1β protein production after 24 h of LPS stimulation. At the mRNA level, misoprostol pre- and posttreatment inhibited LPS-induced TNFα, IL-1β, and IL-6 mRNA production but did not affect IL-8 mRNA. These results indicate that misoprostol exerts anti-inflammatory effects on equine leukocytes when applied before or after a pro-inflammatory stimulus. However, the effects we observed were cytokine-specific and sometimes differed at the mRNA and protein levels. Further studies are warranted to establish the inhibitory effects of misoprostol on equine cytokine production in vivo.

Elimination in long-distance endurance rides: insights from the analysis of 7,032 starts in 80 to 160 km competitions

In equine long-distance endurance competitions, nearly 40% of the starters are eliminated at a veterinary control. Excessive racing speed, the nature of the race venue and the distance covered have been identified as risk factors for elimination. The objective of the present study was to assess whether speed, venue country and the horse’s age are risk factors for elimination, on the basis of individual electronic timing datasets collected during long-distance endurance competitions. Data were obtained for 7,032 horses entered in 80 to 160 km endurance rides in four countries. For each horse and each competition, the datasets included the distance covered, age, average speed, cardiac recovery time and heart rate measured at Vet gate for each phase of the race, and the outcome of the race (i.e. qualification or elimination). For eliminated horses, the reason and phase of elimination were also recorded. An analysis of variance was used to identify and compare variability factors and differences in recorded variables in qualified vs eliminated horses. In the study population, 39% of the starters were eliminated – mostly due to lameness (64%) or metabolic reasons (15%). The eliminated horses displayed a higher speed and worse recovery during the first phases of the race (P<0.05). The mean speed was higher in events organised in the United Arab Emirates, in 2-star rides and in intermediate/mature horses; these factors were associated with slower cardiac recovery and a greater risk of elimination. Our results confirm that excessive speed is a major risk factor for elimination in endurance rides and further indicate that factors such as the venue country, the event distance and the horse’s age are also involved. With a view to increasing completion rates and reducing fatal injuries in endurance races, preventive measures should take these factors into account.

Does oral prednisolone treatment increase the incidence of acute laminitis?

REASONS FOR PERFORMING STUDY

It is accepted among equine practitioners that glucocorticoid treatment is a risk factor for the development of laminitis. However, there is little published evidence of a link between glucocorticoids and laminitis.

OBJECTIVES

To determine whether horses receiving oral prednisolone are at increased risk of laminitis.

STUDY DESIGN

Retrospective case-control study.

METHODS

Clinical records of horses registered with the ambulatory service at Liphook Equine Hospital between January 2001 and November 2014 were reviewed retrospectively to identify horses that had received treatment with oral prednisolone. For each treated horse, 2 time-matched controls that received veterinary attention but were not treated with prednisolone were selected. Incidence of laminitis was compared between the 2 groups and factors associated with laminitis were assessed using Cox regression analysis.

RESULTS

Of the 416 horses treated with prednisolone, 16 (3.8%) were diagnosed with laminitis subsequent to the initiation of prednisolone treatment with an overall incidence of 2.60 (95% CI 1.49-4.22) cases per 100 horse-years at risk. A total of 7 horses (1.7%) developed laminitis during the course of their treatment and 3 (0.7%) of the horses treated with prednisolone were ultimately subjected to euthanasia as a result of laminitis. A total of 46 (5.7%), of the 814 time-matched control horses were diagnosed with laminitis during the study period with an overall incidence of 3.46 (95% CI 2.54-4.62) cases per 100 horse-years at risk. Of these, 12 (1.5%) were subjected to euthanasia as a result of laminitis. There were no significant differences in the overall laminitis incidence rate (P = 0.8), incidence rate during prednisolone treatment (P = 0.09), or probability of laminitis (P = 0.3) between the 2 groups. Mean survival time was greater in the prednisolone than the control group. Equine metabolic syndrome and increasing age were associated with increased risk of laminitis.

CONCLUSIONS

Administration of oral prednisolone did not increase the risk of laminitis.

Quantitative assessment of the equine hoof using digital radiography and magnetic resonance imaging

REASONS FOR PERFORMING STUDY

Evaluation of laminitis cases relies on radiographic measurements of the equine foot. Reference values have not been established for all layers of the foot.

OBJECTIVES

To establish normal hoof wall and sole measurements using digital radiography (DR) and magnetic resonance imaging (MRI) and to document tissue components present in the dorsal hoof wall and solar layers seen on DR.

STUDY DESIGN

Prospective observational case-control study.

METHODS

Digital radiography and MRI were performed on 50 cadaver front feet from 25 horses subjected to euthanasia for nonlameness-related reasons. Four observers measured hoof wall (dorsal, lateral and medial) and sole thickness (sagittal, lateral and medial) using DR and magnetic resonance images. One observer repeated the measurements 3 times. Inter- and intraobserver correlation was assessed.

RESULTS

Digital radiography and MRI measurements for the normal hoof wall and sole were established. Inter- and intraobserver pairwise Pearson's correlation for DR (r>0.98) and MRI measurements (r>0.99) was excellent. Based on MRI, the less radiopaque layer on DR is comprised of the stratum lamellatum and stratum reticulare.

CONCLUSIONS

Normal DR and MRI measurements for the hoof wall and sole were established. On DR images, the less radiopaque layer of the foot observed corresponds to the critical tissues injured in laminitis, the strata lamellatum and reticulare. These reference measurements may be used by the clinician to detect soft-tissue changes in the laminitic equine foot and provide a foundation for future research determining changes in these measurements in horses with laminitis.

Use of laser capture microdissection for the assessment of equine lamellar basal epithelial cell signalling in the early stages of laminitis

REASONS FOR PERFORMING STUDY

Dysadhesion of laminar basal epithelial cells (LBECs) from the underlying dermis is the central event leading to structural failure in equine laminitis. Although many studies of sepsis-related laminitis have reported multiple events occurring throughout the lamellar tissue, there is minimal information regarding signalling events occurring specifically in LBECs.

OBJECTIVES

To determine signalling events in the LBECs during the early stages of carbohydrate-induced laminitis.

STUDY DESIGN

Experimental study.

METHODS

Eight horses were given an overload of carbohydrate (CHO) consisting of corn starch mixture via nasogastric tube. Prior to administration of CHO, lamellar biopsies were taken from the left forefoot (control [CON]). Biopsies were taken from the left hind foot at the onset of fever (developmental [DEV]) and from the right forefoot at the onset of Obel grade 1 lameness (OG1). Laminar basal epithelial cells were isolated from cryosections using a laser capture microdissection (LCM) microscope. Next generation sequencing (RNA-seq) was used to identify transcripts expressed in the LBECs for each time point and bioinformatic analysis was performed with thresholds for between group comparisons set at a greater than 2-fold change and P value ≤0.05.

RESULTS

Forty genes (22 increased/18 decreased) were significantly different from DEV time vs. CON and 107 genes (57 increased/50 decreased) were significantly different from OG1 time vs. CON. Significant increases in inflammatory genes were present in addition to significantly altered expression of genes related to extracellular matrix composition, stability and turnover.

CONCLUSIONS

Signalling related to inflammatory response and extracellular matrix regulation was strongly represented at the DEV and OG1 times. These results indicate that the LBEC is not only a casualty but also an active participant in lamellar events leading to structural failure of the digital lamellae in equine laminitis.

Equine digital veins are more sensitive to superoxide anions than digital arteries

This work was designed to investigate (i) the effect of superoxide dismutase (SOD) inhibition on endothelial function and (ii) the free radical-induced endothelial dysfunction in equine digital veins (EDVs) and equine digital arteries (EDAs) isolated from healthy horses. EDV and EDA rings were suspended in a 5 ml organ bath containing Krebs solution. After a 60 min equilibration period, EDV and EDA rings were contracted with phenylephrine. Then, cumulative concentration-response curves (CCRCs) to acetylcholine were performed. In both EDVs and EDAs, acetylcholine (1 nM to 10 µM) produced concentration-dependent relaxation. We investigated the influence of SOD inhibition by diethyldithiocarbamate (DETC; 100 µM), a CuZnSOD inhibitor, on EDAs and EDVs relaxant responses to acetylcholine. Acetylcholine -mediated relaxation was impaired by DETC only in EDVs. SOD activity assayed by a xanthine-xanthine oxidase method was higher in EDAs compared with EDVs (P<0.05). CCRCs to acetylcholine established in the presence of pyrogallol (30 µM) or homocysteine (20 µM), two superoxide anions generating systems showed that in both EDVs and EDAs, the acetylcholine-mediated relaxation was significantly impaired by pyrogallol and homocysteine. This impairment was more pronounced in EDVs than in EDAs. Moreover, the pyrogallol-induced impairment of acetylcholine-mediated relaxation was potentiated by DETC to a greater extent in EDVs. We concluded that due to the lower activity of SOD, EDVs are more sensitive to superoxide anions than EDAs. So, any alteration of superoxide anions metabolism is likely to have a more important impact on venous rather than arterial relaxation.

Extracellular ATP signaling in equine digital blood vessels

The functional distribution of ATP-activated P2 receptors is well characterized for many blood vessels, but not in the equine digital vasculature, which is a superficial vascular bed that displays thermoregulatory functions and has been implicated in ischemia-reperfusion injuries of the hoof. Isolated equine digital arteries (EDA) and veins (EDV) were submitted to isometric tension studies, whereby electric field stimulation (EFS) and concentration-response curves to exogenously applied agonists were constructed under low tone conditions. Additionally, immunofluorescent localization of P2X and P2Y receptor subtypes was performed. EFS-induced constriction was abolished by tetrodotoxin (1 μM, n=4). Endothelium denudation did not modify the EFS-induced constriction (n=3). The EFS-induced constriction in EDA was inhibited by phentolamine (67.7±1.8%, n=6; 10 μM), and by the non-selective P2 receptor antagonist suramin (46.2±1.3%, n=6; 10 μM). EFS-induced constriction in EDV was reduced by suramin (48.2±2.4%, n=6; 10 μM), the P2 receptor antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (58.3±4.5%, n=6; 10 μM), and phentolamine (23.2±2.5%, n=6; 10 μM). Exogenous methoxamine and ATP mimicked EFS-induced constriction in EDA and EDV. Immunostaining for P2X1, P2X2 and P2X3, and, for P2X1 and P2X7 receptor subunits were observed in EDA and EDV smooth muscle and adventitia, respectively. ATP and noradrenaline are co-transmitters in sympathetic nerves supplying the equine digital vasculature, noradrenaline being the dominant agonist in EDA, and ATP in EDV. In conclusion, P2X receptors mediate vasoconstriction in EDA and EDV, although different P2X subunits are involved in these vessels. The physiological significance of this finding in relation to thermoregulatory functions and equine laminitis is discussed.

Laminitic pain: parallels with pain states in humans and other species

Laminitis poses a threat to all horses, and is widely considered as being one of the most important diseases of horses and a global equine welfare problem. The effects of laminitis lead to debilitation, development of pronounced digital pain, and great suffering in the afflicted animal. The precise pathophysiological processes that result in laminitic pain are poorly defined, and hence the delivery of effective palliative care is clinically challenging. Knowledge and understanding of pain states in other animal species may further aid the elucidation of equine laminitic pain mechanisms, guide the search for treatable causes of this multifactorial problem, and thereby help achieve enhanced therapeutic and palliative care. However, parallels drawn from pain states in other animals must consider species differences in both anatomy and physiology, and the specific nature of the laminitic disease process.

RT-qPCR comparison of mast cell populations in whole blood from healthy horses and those with laminitis

Inflammatory damage to the digital laminae, a structure responsible for suspension of the distal skeleton within the hoof capsule, results in a painful and often life-threatening disease in horses called laminitis. There can be many diverse causes of laminitis; however, previous work in the horse has suggested that in each case, the inflammation and resulting tissue damage is consistent with the action of mediators released from mast cells (MC), as well as the downstream consequences of their activation. The recent development of molecular genetics tools to characterize cells based on their transcriptional activity makes a new approach for measuring MCs possible. Healthy thoroughbred horses from a variety of age groups were used to assess the amount of variation in KIT (encoding mast cell growth factor receptor) and TPSB2 (encoding mast cell tryptase beta 2) gene expression present in the population and to establish "normal" values. Horses (n=9) with a wider range of body condition scores (3-8), because of a more lax management setting that could predispose them to laminitis, had significantly higher KIT expression in circulating peripheral blood cells than horses under individualized management conditions (n=10) that produced ideal body condition scores (4-6) (mean 2.573-fold, P<0.0005). Likewise, horses affected with acute laminitis (n=11) had elevated expression of TPSB2 (2.760-fold, P=0.0011) relative to control horses (n=15). These data suggest that investigation of MC-related genes KIT and TPSB2 may be effective to assay MC population and activity. More work is needed to refine the diagnostic criteria to better describe at what point MC activation occurs and illustrate the use of gene expression assays in clinical cases of laminitis. Additionally, MC activation is associated with inflammatory disease in several mammalian species and may prove a valuable therapeutic target in the horse.

Acute laminitis: medical and supportive therapy

Acute laminitis is a serious complication of many primary conditions in the horse. This article summarizes the most appropriate approach to management of the horse with acute laminitis, based on current information.

Therapeutic hypothermia (cryotherapy) to prevent and treat acute laminitis

Digital hypothermia successfully reduces the severity of experimentally induced laminitis. Continuous-distal limb cryotherapy may be a useful technique in clinical cases that are at risk of developing laminitis. This article examines the effects of hypothermia on tissue as well as the rationale, and suggested protocols for the usage of distal limb cryotherapy in the prevention and treatment of laminitis.

Comparative study of the properties of tendinocytes derived from three different sites in the equine superficial digital flexor tendon

This aim of this study was to determine the characteristic differences in tendinocytes derived from three sites of the equine superficial digital flexor tendon (SDFT)-proximally the myotendinous junction (MTJ), mid-metacarpal (mM) and osteotendinous junction (OTJ)-in morphology, proliferation, and ability for synthesis of collagen and matrix metalloproteinases (MMPs). Little difference was observed in cell proliferation. Addition of tumor necrosis factor (TNF) alpha to the culture medium resulted in increased collagen synthesis by tendinocytes from all three sites. The amount of collagen synthesized by tendinocytes derived from the mM and OTJ was much larger than that synthesized by untreated tendinocytes. A collagen zymogram revealed that proMMP-13 synthesis was increased towards the distal site. However, TNFalpha treatment resulted in a significant decrease in the amount of proMMP-13 synthesized by tendinocytes from all three sites. On the other hand, a gelatin zymogram showed that the synthesis level of proMMP-9 tended to decrease towards the distal site, but there was little difference between synthesis levels of proMMP-9 before and after TNFalpha treatment. These results indicated that tendinocytes in the same tendon have different characteristics and that these characterisities would reflect the function of tendinocytes in vivo. Also, the isolated tendinocytes provided much information on the characteristics and properties of tendons for the ECM turnover system and on the responsiveness of tendinocytes to complex inflammatory responses in a tendinopathy condition.

Evaluation of activation of protein kinase C during agonist-induced constriction of veins isolated from the laminar dermis of horses

OBJECTIVE

To determine the effects of the protein kinase C (PKC) inhibitor, Ro-31-8220, on agonist-induced constriction of laminar arteries and veins obtained from horses.

SAMPLE POPULATION

Laminar arteries and veins obtained from 8 adult mixed-breed horses.

PROCEDURES

Laminar arteries and veins were isolated and mounted on small vessel myographs for the measurement of isometric tension. Concentration-response curves were then obtained for the vasoconstrictor agonists phenylephrine, 5-hydroxytryptamine, prostaglandin F(2), and endothelin-1. All responses were measured with or without the addition of Ro-31-8220 (3 microM).

RESULTS

Laminar veins were more sensitive to vasoconstrictor agonists than laminar arteries, and incubation of laminar veins with Ro-31-8220 resulted in significantly smaller agonist-induced contractile responses for all agonists tested. In contrast, Ro-31-8220 had no effect on agonist-induced contractile responses of laminar arteries.

CONCLUSIONS AND CLINICAL RELEVANCE

Results of the study were consistent with activation of PKC being confined to agonist-induced contraction of laminar veins isolated from the laminar dermis of horses. Consequently, the possible involvement of PKC in the venoconstriction observed during the development of laminitis is worthy of further investigation.

Countermeasures for pasture-associated laminitis in ponies and horses

Laminitis occurs throughout the world in horses and ponies and has major welfare implications. It is obviously important to be able to recognize and treat the condition in its early stages so that pain and suffering are kept to a minimum. However, ideally it would be preferred to be able to recommend certain interventions/countermeasures that avoid or prevent the condition from occurring in the first place. Because pasture-associated laminitis occurs with grass consumption, one obvious way to avoid the condition is to prevent access to pasture and to feed forage alternatives that are known to be low in rapidly fermentable material. For the majority of horses, total restriction is not always a viable or desired option for financial, welfare, and health reasons. It also may not be necessary for those animals that are not predisposed to laminitis. This review discusses the possible countermeasures that could be considered now and in the future in the following 7 key areas: 1) Identifying animals predisposed to the condition; 2) Limiting development of insulin resistance; 3) Avoiding high intakes of rapidly fermentable material; 4) Preventing/reducing the formation and absorption of the various "triggering factors"; 5) Reducing/preventing oxidative damage; 6) Preventing/reducing matrix metalloproteinase activity; and 7) Preventing changes in blood flow. It is unfortunate that little or no hard data exist at present on effective countermeasures, only mechanistic evidence for avoiding risk factors. However, there is much to gain, and research in this area is urgently required.