Owner perceptions and experiences with equine necropsy.

In recent years, the number of horses submitted for necropsy has been in decline. This study aimed to identify the perceptions and barriers of equine necropsy through an online survey of horse owners. The data were analyzed by multivariate models for associations and factors that influenced decision making regarding necropsy. The survey yielded 1,366 usable responses. Respondents had higher familiarity with the term "autopsy" compared to "necropsy" (P < 0.001) and showed a greater level of comfort using the terms "body" and "mortality" compared to "carcass" (P < 0.001). Most respondents (82 %) had experienced euthanizing a horse, but few (27 %) were offered a necropsy. Of those offered a necropsy, a majority (81 %) opted to perform one. When asked about their reasons for choosing to have a necropsy performed, recommendations from veterinarians (77.87 OR, 95 % CI: 49.3, 127.5) and already knowing the cause of death (1.85 OR, 95 % CI: 1.2, 30) were positively associated while a benefit to herd health was negatively associated (0.55 OR, 95 % CI: 0.3, 1.0). Owning horses for use as competition animals (1.44 OR, 95 % CI: 0.9, 2.2), the desire for personal closure (1.76 OR, 95 % CI: 1.1, 2.9), and the goals to protect human health (1.29 OR, 95 % CI: 1.0, 1.6) and to improve herd health (1.43 OR, 95 % CI: 1.1, 1.9) were positively associated with a likelihood of choosing to have a necropsy performed or recommending necropsies in the future. This research highlights the need for education of horse owners about the option and benefits of necropsy, and the use of more societally accepted language.

The effect of a limit-fed diet and slow-feed hay nets on morphometric measurements and postprandial metabolite and hormone patterns in adult horses.

Modern horse management systems tend to limit a horse's opportunity to forage, rely on meal feeding, and may contribute to the increase in equine obesity. The use of slow-feed hay nets represents an opportunity to extend foraging time while feeding a restricted diet. The objectives of this study were to determine if limit feeding combined with a slow-feed hay net would affect morphometric measurements and postprandial metabolite and hormone patterns in overweight adult horses. Eight adult Quarter horses (BW 563 kg ± 4.6 kg; BCS 7.2 ± 0.3) were used in a randomized complete block design, with 4 horses assigned to feeding hay off the stall floor (FLOOR) and 4 horses assigned to feeding from a slow-feed hay net (NET). Horses were fed in individual stalls at 1% BW each day, split evenly between 2 meals at 0700 and 1600 h. Body weight, BCS, neck and girth circumference, cresty neck score, and ultrasound measurements of average rump fat, longissimus dorsi (LD) depth, and LD thickness were taken on d 0, 14, and 28. Three 24-h blood samplings were conducted on d 0, 14, and 28 and were analyzed for glucose, insulin, cortisol, and leptin concentrations. Samplings occurred every 30 min for 3 h postfeeding, with hourly samples occurring between feedings. Horses feeding from the FLOOR took less time to consume their hay meal compared with horses feeding from the NET ( < 0.001). All horses lost weight over the 28-d period ( < 0.0001); however, no difference was observed between treatments. There was no difference in BCS, neck and girth circumference, cresty neck score, rump fat, or LD depth between days or treatments ( ≥ 0.25). There was an effect of day on LD thickness in horses feeding from the NET. Longissimus dorsi thickness was lower on d 28 compared with that on d 0 ( = 0.0257). Only time to peak insulin and peak cortisol were affected by treatment ( ≤ 0.037), with horses feeding from the NET having lower values than horses feeding from the FLOOR. Average glucose, insulin, cortisol, and leptin were affected by day ( ≤ 0.0102). Glucose and insulin values increased, whereas cortisol and leptin levels decreased throughout the 28-d study. The use of a slow-feed hay net coupled with a limit-fed diet appears to be an effective method for decreasing BW and maintaining more homeostatic levels of postprandial metabolites and hormones when feeding overweight adult horses.

Estimation of body weight and development of a body weight score for adult equids using morphometric measurements.

Excessive BW has become a major health issue in the equine (Equus caballus) industry. The objectives were to determine if the addition of neck circumference and height improved existing BW estimation equations, to develop an equation for estimation of ideal BW, and to develop a method for assessing the likelihood of being overweight in adult equids. Six hundred and twenty-nine adult horses and ponies who met the following criteria were measured and weighed at 2 horse shows in September 2011 in Minnesota: age ≥ 3 yr, height ≥ 112 cm, and nonpregnant. Personnel assessed BCS on a scale of 1 to 9 and measured wither height at the third thoracic vertebra, body length from the point of shoulder to the point of the buttock, neck and girth circumference, and weight using a portable livestock scale. Individuals were grouped into breed types on the basis of existing knowledge and were confirmed with multivariate ANOVA analysis of morphometric measurements. Equations for estimated and ideal BW were developed using linear regression modeling. For estimated BW, the model was fit using all individuals and all morphometric measurements. For ideal BW, the model was fit using individuals with a BCS of 5; breed type, height, and body length were considered as these measurements are not affected by adiposity. A BW score to assess the likelihood of being overweight was developed by fitting a proportional odds logistic regression model on BCS using the difference between ideal and estimated BW, the neck to height ratio, and the girth to height ratio as predictors; this score was then standardized using the data from individuals with a BCS of 5. Breed types included Arabian, stock, and pony. Mean (± SD) BCS was 5.6 ± 0.9. BW (kg) was estimated by taking [girth (cm)(1.48)6 × length (cm)(0.554) × height (cm)(0.599) × neck (cm)(0.173)]/3,596, 3,606, and 3,441 for Arabians, ponies, and stock horses, respectively (R(2) = 0.92; mean-squared error (MSE) = 22 kg). Ideal BW (kg) was estimated by taking [length (cm) × 2.8] + [height (cm) × 4.2] - 611, 606, and 577 for Arabians, ponies, and stock horses, respectively (R(2) = 0.86; MSE = 24). Equids with a BCS of ≥ 7 had a greater likelihood of being overweight, and the model suggested cutoffs at the 48th and 83rd percentiles for underweight and overweight individuals, respectively. Morphometric measurements were successfully used to develop equid BW-related equations.

Effect of hay steaming on forage nutritive values and dry matter intake by horses.

Management strategies for horses with respiratory disease include soaking hay before feeding. Hay steaming is an alternative to this practice; however, little is known about its impact on forage nutritive values or intake. The objective was to determine the effect of steaming on forage nutritive value and intake by horses. Two alfalfa (Medicago sativa L.)-orchardgrass (Dactylis glomerata L.) mixed hays were evaluated: a low moldy (NM) and moderately moldy (MM) hay. Six mature horses were used in a 10 d crossover design. Three horses were assigned to each hay type and treatments were switched on d 6. Each day, one bale of each hay was sampled (pre- and poststeaming) and steamed for 90 min using a commercial hay steamer. Two flakes of steamed or unsteamed NM or MM hay were weighed and offered simultaneously to each horse in individual hay nets. Horses were allowed access to hay for 2 h, orts were collected, and 2 h DMI was calculated. Six additional bales of NM and MM were used to evaluate the effect of steaming on total suspended particulate (TSP). Flakes of unsteamed or steamed hay were agitated in an electric cement mixer, and TSP were recorded every min for 30 min using a tapered element oscillating microbalance sampler. Paired t tests and PROC MIXED of SAS (SAS Inst. Inc., Cary, NC) were used to compare steamed and unsteamed hay nutritive values, mold concentration, TSP, and 2 h DMI. Steaming increased hay moisture and therefore reduced DM to 77 and 81% for NM and MM, respectively (P < 0.001). In NM and MM hay, steaming reduced P content by 16 and 17%, respectively (P ≤ 0.007). Steaming reduced water-soluble carbohydrates (WSC) and ethanol-soluble carbohydrates (ESC) by 13% (P = 0.001) and 27% (P = 0.003), respectively, for MM but had no effect on NM (P > 0.05). Steaming reduced mold concentrations in both hays by ≥ 91% (P < 0.001). Total suspended particulate of MM hay was reduced by 55% (P = 0.043), but TSP in NM hay was not affected by steaming (P = 0.445). Dry matter intake of NM was increased by steaming; horses ingested 0.64 kg of unsteamed and 2.02 kg of steamed hay (P < 0.001). Dry matter intake of MM was not affected by steaming (P > 0.05). For NM hay, steaming decreased P and mold concentrations and increased DMI of the hay but had no effect on TSP. In MM hay, steaming reduced P, WSC, ESC, mold concentrations, and TSP but did not affect DMI. Steaming represents a strategy for reducing TSP and mold concentrations and increasing DMI in some hays but can result in leaching of essential nutrients.

Seasonal pasture myopathy/atypical myopathy in North America associated with ingestion of hypoglycin A within seeds of the box elder tree.

REASONS FOR PERFORMING STUDY: We hypothesised that seasonal pasture myopathy (SPM), which closely resembles atypical myopathy (AM), was caused by ingestion of a seed-bearing plant abundant in autumn pastures. OBJECTIVES: To identify a common seed-bearing plant among autumn pastures of horses with SPM, and to determine whether the toxic amino acid hypoglycin A was present in the seeds and whether hypoglycin metabolites were present in SPM horse serum or urine. METHODS: Twelve SPM cases, 11 SPM pastures and 23 control farms were visited to identify a plant common to all SPM farms in autumn. A common seed was analysed for amino acid composition (n = 7/7) by GC-MS and its toxic metabolite (n = 4/4) identified in conjugated form in serum [tandem mass spectrometry (MS/MS)] and urine [gas chromatography (GC) MS]. Serum acylcarnitines and urine organic acid profiles (n = 7) were determined for SPM horses. RESULTS: Seeds from box elder trees (Acer negundo) were present on all SPM and 61% of control pastures. Hypoglycin A, known to cause acquired multiple acyl-CoA dehydrogenase deficiency (MADD), was found in box elder seeds. Serum acylcarnitines and urine organic acid profiles in SPM horses were typical for MADD. The hypoglycin A metabolite methylenecyclopropylacetic acid (MCPA), known to be toxic in other species, was found in conjugated form in SPM horse serum and urine. Horses with SPM had longer turn-out, more overgrazed pastures, and less supplemental feeding than control horses. POTENTIAL RELEVANCE: For the first time, SPM has been linked to a toxin in seeds abundant on autumn pastures whose identified metabolite, MCPA, is known to cause acquired MADD, the pathological mechanism behind SPM and AM. Further research is required to determine the lethal dose of hypoglycin A in horses, as well as factors that affect annual seed burden and hypoglycin A content in Acer species in North America and Europe.