Pasture-Associated Laminitis

doi:10.1016/j.cveq.2009.01.004

Veterinary Clinics of North America: Equine Practice

Volume 25, Issue 1, April 2009, Pages 39-50

https://doi.org/10.1016/j.cveq.2009.01.004 Get rights and content

Laminitis is a painful and debilitating condition of horses and ponies that has major economic and welfare implications. Anecdotal observations and the results of survey studies have indicated that most laminitis cases occur in horses and ponies kept at pasture (hence, the term pasture-associated laminitis). Risk for development of pasture-associated laminitis represents a dynamic interaction between animal predisposing factors (an insulin-resistant phenotype commonly termed equine metabolic syndrome) and environmental conditions, particularly the nonstructural carbohydrate (simple sugars, starches, and fructans) content of pasture forage. Countermeasures for avoidance of pasture-associated laminitis involve (1) mitigation of metabolic predisposition (insulin resistance and obesity) in high-risk horses and ponies and (2) dietary and pasture grazing management strategies that minimize exposure to the dietary conditions known to trigger laminitis in susceptible animals.

Section snippets

Epidemiology and risk factors

Anecdotal observations have indicated that pasture-induced laminitis occurs at times of rapid grass growth and the accumulation of certain carbohydrates (fructans, starches, and sugars) in pasture forage (during the spring and early summer and during the fall, particularly after rainfall). Surprisingly, few studies have examined the effect of time of year on the incidence of laminitis. Some reports3, 4, 5 have indicated increased risk during spring and summer, whereas others have failed to

Pathogenesis of pasture laminitis

Pasture-associated laminitis clearly has a nutritional basis, but the exact mechanism(s) that links the consumption of pasture forage to development of laminar failure is not known. In broad terms, the ingestion of pasture forage may trigger laminitis by means of induction of digestive or metabolic disturbances. At certain times of the year, pasture forage is rich in nonstructural carbohydrates (NSCs), including simple sugars, starches, and fructans.²³ Rapid fermentation of these carbohydrates

Countermeasures to pasture laminitis in high-risk animals

From the preceding discussion, it is evident that countermeasures to pasture-associated laminitis must focus on two areas: (1) mitigation of metabolic predispositions (IR and obesity) in high-risk horses and ponies and (2) strategies for limiting intake of NSCs from pasture and other feedstuffs (ie, minimizing exposure to the dietary conditions known to trigger laminitis in these susceptible animals). Horses and ponies with a history of laminitis or physical characteristics suggestive of EMS or

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Changes in the nutrient profile and the load of mycotoxins, phytoestrogens, and pesticides in horse pastures during spring and summer in Austria
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Pastures are used for grazing and the production of conserved roughage in horses. Yet, the nutritional profile of the forage varies from spring to late summer, affecting equine nutrient supply and health. In addition, environmental factors may also favor plant contaminants such as mycotoxins. This study aimed to determine the nutritional profile and contaminant load of selected horse pastures from early spring till late summer. The nutrient composition (main macronutrients, macro elements and trace elements), as well as mycotoxins, metabolites, pesticides, and plant-derived compounds of seven horse pastures were analyzed. Each pasture was sampled three times and the samples were categorized according to the status of the pasture plants: ear emergence, early- till full bloom, and drought-damaged vegetation. Drought-damaged pastures demonstrated a rise in the acid to neutral detergent fiber ratio, calcium, iron, and magnesium but lower potassium contents. Mycotoxins and other contaminants were found in the pastures including 64 fungal compounds (ergot alkaloids (13) and metabolites from Fusarium (21), Aspergillus (2), Penicillium (8), Alternaria (8) and other fungal species (12), one bacterial metabolite (cereulide), twelve plant metabolites (including eight phytoestrogens and three cyanogenic glycosides (linamarin, lotaustralin and prunasin)), 11 nonspecific metabolites and six pesticides. Fusarium metabolites showed the highest concentrations among the fungal metabolites and drought-induced stress increased the contamination levels (range: 123-3873 µg/kg DM). In conclusion, there was a dominant effect of the developmental stages of the plants, botanical composition of the pastures and weather conditions on the nutritional composition and presence of contaminants on pastures.
The Use of Confined Housing in Sand Bedding and Trimming to Manage Phalangeal Rotation and Hoof Malconformation Over a 20-Week Period in Two Laminitic Stallions
2022, Journal of Equine Veterinary Science
Chronic laminitis is a late stage of laminitis in horses characterised by distal phalangeal rotation and foot pain. Various trimming and shoeing methods have been implemented; however, they sometimes aggravate lameness, particularly in laminitic horses with poor hoof quality. Sand bedding confinement has alternatively been employed to relieve foot pain in laminitic horses; however, the impact of long-term confined sand bed accommodation on hoof conditions is unknown. Moreover, the time course of sand bedding housing for managing chronic laminitis has yet to be described. We report the outcome of long-term housing in sand bedding confinement on hoof architectures and the time required for appropriate management of hoof malconformation. Two stallions, diagnosed with bilateral chronic laminitis and showing severe lameness following therapeutic shoeing, were assigned barefoot to confined sand bedding accommodations. Sole depth increased starting at 8 weeks; however, heel depth did not change throughout the housing period. A decrease in hoof angles was detected at 20 weeks of housing. An increase in sole depth/heel depth ratios was strongly correlated with the reduction in hoof angles. Therefore, long-term housing in sand bedding confinement for at least 20 weeks corrected phalangeal rotation and improved hoof conformation in two stallions with bilateral chronic laminitis. Further validation with a larger sample size is needed to determine whether this strategic housing management provides an alternative approach to treating hoof problems in laminitic horses that respond poorly to shoeing management.
“Feeding the Foot”: Nutritional Influences on Equine Hoof Health
2021, Veterinary Clinics of North America - Equine Practice
Effect of Sward Height on Pasture Nonstructural Carbohydrate Concentrations and Blood Glucose/Insulin Profiles in Grazing Horses
2017, Journal of Equine Veterinary Science
Citation Excerpt :
Decreasing the sward height by frequent mowing decreased NSC available for grazing and subsequently decreased the insulin response of horses grazing the pasture. This finding may have implications for developing grazing strategies aimed at decreasing the risk of pasture-associated laminitis [1,5]. For example, mowing pasture during seasons of the year when cool season grass NSC concentrations are highest (e.g., spring and fall) could maintain forage in a “regrowth” phase that consumes stored NSC, thereby decreasing overall NSC concentration.
Six mature stock-type geldings with maintenance only requirements were used in a randomized cross-over design to determine the effect of sward height on pasture plant nonstructural carbohydrate (NSC) concentrations and blood glucose and insulin concentrations. Horses were randomly assigned to one of two tall fescue (Lolium arundinaceum Schreb cv Max-Q, Pennington Seed, Madison, GA) grazing cells (0.37 ha) having two different sward heights for a period of 7 days: (1) short (approximately 15 cm; n = 3) or tall (between 30 and 40 cm; n = 3). After the first 7-day period, treatment groups were reversed by moving horses to ungrazed cells having similar characteristics to those used in the first 7 days, so that all horses receive all treatments resulting in six observations per treatment. Both short and tall grazing cells were mowed to a height of approximately 15 cm 32 days before the experiment starts. The short grazing cells were removed to approximately 15 cm at 11 days before the start of the first 7-day period and again 1 day before the start of each 7-day period. All horses had access to pasture for 10 h/d beginning at 8 AM and ending at 6 PM. Although not at pasture, all horses were individually housed in 3.7 × 12.2 m partially covered pens containing automatic water troughs and a crushed stone surface. Herbage mass (kg DM/ha) was determined by use of a falling plate meter for each pasture to ensure that both groups of horses had adequate dry matter to provide grazing for at least 7 days. On day 7 of each period, jugular venous blood samples were collected from each horse before being turned out to pasture, and then at 2, 4, 6, and 8 hours after turn-out. Pasture samples were also collected from each grazing cell at the same time blood samples were taken. Serum and plasma from blood samples were harvested and analyzed for insulin and glucose concentrations, respectively. Pasture samples were analyzed for water soluble carbohydrate (WSC), ethanol soluble carbohydrate (ESC), and starch. The sum of WSC and starch were used as an estimate of NSC. Area under the curve (AUC) and peak concentration were calculated for both plasma glucose (PPG) and serum insulin (PSI) concentration and were analyzed using analysis of variance for randomized cross-over designs. Pasture WSC, ESC, starch, and NSC concentrations were analyzed using analysis of variance for randomized complete block design. A P value of < .05 was considered significant. Mean pasture plant NSC, WSC, and ESC concentrations were lower (P < .001) in short as compared with tall. Pasture plant starch concentration was not different between treatments. Mean pregrazing plasma glucose concentrations, PPG concentrations, and plasma glucose AUC were not affected by treatment. Mean pregrazing serum insulin concentrations were not affected by treatment. Mean PSI and insulin AUC were greater (P < .01) when horses grazed tall, as compared with short. In conclusion, decreasing the sward height by mowing pasture decreased NSC, WSC, and ESC concentrations and subsequently decreased the postprandial insulin response of horses grazing the pasture. These findings may be important in developing strategies aimed at preventing insulin resistance in grazing horses.
Markers for Predicting Overweight or Obesity of Broodmares
2017, Journal of Equine Veterinary Science
Citation Excerpt :
Insulin resistance in obese horses is known as equine metabolic syndrome [16]. Horses and ponies with equine metabolic syndrome developed laminitis [4,17]. Clinically normal ponies treated with insulin also developed clinical and histological laminitis [18].
Obesity has become of great concern to all equine community from both veterinary and welfare points of view. For estimating obesity markers of brood mares, 17 mares with body conditions were subjected to blood sampling and ultrasound examination to measure rump fat for 6 consecutive weeks. Body length (L), girth (G), and height (H) were measured to estimate body weight (BW), body fat %, body fat mass (BFM) and body mass index (BMI). Mares were classified into three groups according to body condition score (BCS) and rump fat thickness (RF). Overweight mares (O) had BCS >7 and RF >7 mm, moderate (M) had BCS and RF >3 to ≤7, and emaciated (E) had BCS and RF ≤ 3 mm. Glucose, triglycerides, nitric oxide (NO), insulin, insulin-like growth factor-I (IGF-1), leptin, ovarian hormones, and thyroid hormones were measured. Results revealed that BCS, G, L, L × G × H, BW, RF, fat %, and BFM correlated significantly (P < .0001) with body condition. Tetraiodothyronine concentrations of E mares were significantly high (P = .04), but triiodothyronine concentrations tended (P = .07) to be low. Insulin (P = .06) and IGF-1 (P = .07) concentrations tended to be high in O mares. Moderate mares had the highest leptin concentrations (P = .007), but E mares had the lowest P4 concentrations (P = .01). Overweight mares had nonsignificantly high glucose, NO, and triglycerides. In conclusion, back fat and morphometric measurements are the easiest and simple assessment of overweight and obesity. Obese and overweight mares showed slight hyperinsulinemia, hypertriglyceridemia, and hyperglycemia. Hyperleptinemia alone is not indicative of obesity.
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Pasture-Associated Laminitis

Section snippets

Epidemiology and risk factors

Pathogenesis of pasture laminitis

Countermeasures to pasture laminitis in high-risk animals

Vet J

Vet Clin North Am Equine Pract

Prev Vet Med

Am J Med Sci

J Nutr

J Nutr

Vet J

J Nutr

The epidemiology of equine laminitis in the UK

The prevalence of laminitis in one region of the UK

Descriptive epidemiological study of equine laminitis

Equine Vet J

Age, breed, sex and seasonality as risk factors for equine laminitis

Prev Vet Med

Evaluation of genetic and metabolic predispositions and nutritional risk factors for pasture-associated laminitis in ponies

J Am Vet Med Assoc

Insulin tolerance in laminitic ponies

Can J Comp Med

Physical characteristics, blood hormone concentrations, and plasma lipid concentrations in obese horses with insulin resistance

J Am Vet Med Assoc

Prediction of incipient pasture-associated laminitis from hyperinsulinemia, hyperleptinemia and generalized and localized obesity in a cohort of ponies

Equine Vet J

Hypertension and insulin resistance in a mixed-breed population of ponies predisposed to laminitis

Am J Vet Res

Determination of reference range values indicative of glucose metabolism and insulin resistance by use of glucose clamp techniques in horses and ponies

Am J Vet Res