Effect of daily floor treatment with sodium bisulfate on the fly population of horse stalls

OBJECTIVE: To determine application rate and effectiveness of sodium bisulfate to decrease the fly population in a horse barn environment. SAMPLE POPULATION: 12 privately owned farms in southeastern Pennsylvania. PROCEDURE: Application rates of sodium bisulfate were approximately 2.3 kg/stall, 1.1 kg/stall, and 0.5 kg/stall. Two or 3 stalls were treated, and 1 or 2 stalls were not treated (control stalls) at each farm. Farm personnel applied sodium bisulfate in treated stalls daily for 7 days. Fly tapes were hung from the same site in treated and control stalls. After 24 hours, the fly tape was removed, flies adhering to the sticky surface were counted and recorded, and a new fly tape was hung. This procedure was repeated daily during each of the testing periods. RESULTS: Following the application of 2.3 kg of sodium bisulfate/stall, the numbers of flies collected on the fly tape were significantly decreased in treated stalls, compared with control stalls during the same time periods on 9 of the 12 farms evaluated. Following the application of 1.1 kg of sodium bisulfate/stall, fly numbers were significantly decreased in treated stalls on 6 of the 9 farms evaluated. Following the application of 0.5 kg of sodium bisulfate/stall, fly numbers were significantly decreased in the treated stalls on 3 of the 4 farms evaluated. CONCLUSIONS AND CLINICAL RELEVANCE: Our findings suggest that sodium bisulfate would be effective for fly control in horse barns.     

Respiratory and environmental effects of recycled phone book paper versus sawdust as bedding for horses

The physiological effect on the equine respiratory tract of recycled phone book paper vs. sawdust bedding was investigated in 12 mares with no clinical signs of respiratory disease. Mares were housed in a 20-stall barn and randomly assigned to one of two treatment groups (Group 1=sawdust; Group 2=phone book paper) for 14 days. After a 14-day turnout, Group 1 was assigned to phone book paper and Group 2 was assigned to sawdust for 14 days using a crossover experimental design. Endoscopic examinations of the upper respiratory tract and trachea along with tracheal washes (TW) were performed on days 0 and 14 of each trial. Cytologic examinations were performed on TW samples. Cell type and laboratory interpretation of TW samples were noted. There was no difference (P>0.05) in cell type between treatment groups within or across trials. Laboratory interpretation indicated no abnormalities in 30 of 48 TW samples. Stall conditions were visually rated and graded daily for drinking water cleanliness, depth of bedding and absorbency, overall cleanliness, ammonia odor, and aerial ammonia levels. The phone book paper bedding was more absorbent (P<0.01), had a cleaner appearance (P<0.01), and had lower aerial ammonia levels (P<0.01) than the sawdust bedding. The phone book paper was effective in controlling aerial ammonia and did not adversely affect the respiratory health of clinically normal horses based on the diagnostic tests performed in this study. Phone book paper did effect the outward appearance of the horses, as horses housed on phone book paper had a dustier outward appearance. In addition, pigment was seen in the TW samples of 12 horses bedded on phone book paper, whereas it was rarely noted in horses bedded on sawdust. Overall, phone book paper appeared to be a viable option for horse bedding when compared to sawdust.     

Effect of a pelleted supplement fed during and after omeprazole treatment on nonglandular gastric ulcer scores and gastric juice pH in horses

Gastric ulcers are common in horses. The purpose of this study was to test the effect of a commercially available supplement, SmartGut^® Ultra pellets (SmGU) on gastric ulcer scores and gastric juice pH after omeprazole treatment in stall‐confined horses. Eight Thoroughbred horses were studied in a 2‐period, 2‐treatment crossover design, where the SmGU (40 g, twice daily) was mixed in grain feed. Horses were stall‐confined and treated with the supplement or control for 6 weeks, consisting of 2 weeks (Days 1–14) omeprazole treatment, 2 weeks (Days 14–28) following discontinuation of omeprazole treatment, one week (Days 28–35) alternating feed deprivation to induce or worsen existing ulcers and a one week (Days 35–42) recovery period. Gastroscopy was performed and gastric juice pH measured on Days 0, 14, 28, 35 and 42. Gastric ulcer lesion number (NGN) and severity (NGS) scores were assigned to each horse by an investigator (F.M.A.) masked to treatment. On Day 0 before treatment, mean NGN and NGS scores and gastric juice pH were not different (P>0.05) between treatment groups. By Day 14, mean NGN and NGS scores decreased (P<0.05) in both treatment groups. By Days 28 and 35, mean NGN score significantly increased in the untreated control horses but not the SmGU‐treated horses. By Day 42, mean NGN and NGS scores were not different in either group and were significantly lower than Day 0. Mean gastric juice pH was higher in both groups on Day 14 as a result of omeprazole treatment when compared with other days. SmartGut^® Ultra supplement added to the feed prevented the worsening of gastric ulcer number 2 weeks after omeprazole treatment, without altering the gastric juice pH. Supplementation with SmGU might aid in protection of the nonglandular stomach from recurrence of ulcers after omeprazole treatment in stall‐confined horses undergoing intermittent feeding.     

Incidence of respiratory disorders during housing in non-weaned Charolais calves in cow-calf farms of Pays de la Loire (Western France)

We assessed the incidence rate of respiratory disorders during the 1999–2000 housing period in non-weaned calves reared in a specific cow–calf farming system in western France, examined its variations according to age of the calf, housing facility and meteorological conditions, and described the different time-distribution patterns of incident cases within the barns. Treatments for respiratory disorders were recorded by the farmers on a specific sheet according a written definition provided. A case “occurred” on a given day if the calf concerned was treated for respiratory disorder on this day but not in the previous 14 days. At the barn level, episodes of respiratory disorder were determined based on the time-distribution of incident cases. An episode started on a given day if at least one case occurred on this day in the barn concerned without any cases occurring in the previous 14 days. Data were suitable for analysis for 6813 calves, in 199 barns, located in 137 farms, where no metaphylactic treatment (mass treatment of ill and not-ill calves at the barn level) was implemented. The incidence rate of respiratory disorders was 1.89 cases per 1000 calf-days at-risk. The proportion of reoccurrent cases was 8.6%. During the 1999–2000 housing period, cases occurred more frequently between 1 November and 20 January. The incidence rate of cases peaked between 14 and 20 days of age and was lower after 105 days of age. Large variation in incidence existed among barns. In one-third of the buildings, no case was observed. A higher incidence of cases was observed in loose-housing yards compared to tied-cow stalls. No clear trend between daily meteorological measurements and daily incidence rate of cases was evidenced. A total of 11 barn-level episodes occurred in 9 tied-cow stalls and 229 barn-level episodes occurred in 120 loose-housing yards. Large variations in the characteristics of episodes (duration, incidence of sick calves) and in their time-distribution existed between barns.     

Detection of Salmonella organisms and assessment of a protocol for removal of contamination in horse stalls at a veterinary teaching hospital

OBJECTIVES: To assess methods of detecting environmental contamination with Salmonella organisms and evaluate a cleaning and disinfection protocol for horse stalls in a veterinary teaching hospital. DESIGN: Original study. SAMPLE POPULATION: 37 horses with diarrhea likely to be caused by Salmonella infection and their stall environments. PROCEDURES: Fecal samples were collected from horses daily during hospitalization; samples were obtained from stall sites after cleaning and application of disinfectants. Fecal and environmental samples were cultured for Salmonella spp and tested via polymerase chain reaction (PCR) assay to detect Salmonella DNA. RESULTS: 1 horse died and 2 were discharged prior to sample collection. Fecal samples from 9 of 34 horses yielded growth of Salmonella organisms on bacteriologic culture, and 23 yielded positive results via PCR assay on > or = 1 occasion. Among environmental samples from 21 stalls, salmonellae were detected at > or = 1 stall site on 6 of 78 occasions, and > or = 1 stall site yielded positive results via PCR assay on 69 of 77 occasions. Salmonella DNA was detected more frequently in samples of stall drains, cracks, and corners. Salmonella spp were cultured from samples of 3 stalls after both initial and second cleaning and disinfection cycles, but no organisms were detected in samples obtained after use of a peroxygen disinfectant. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that stalls in which horses with salmonellosis were housed should only be used to accommodate newly hospitalized horses after samples (collected after 2 cycles of cleaning and disinfection) from drains, cracks, and corners yield negative results on bacteriologic culture.     

Recovery of horses from general anesthesia in a darkened or illuminated recovery stall

ObjectiveTo assess whether recovery from general anesthesia, in an illuminated or a darkened stall, has an effect on time to first movement, time to standing, and recovery score.Study designProspective randomized clinical study.AnimalsTwenty-nine healthy, 2- to 5-year-old horses undergoing surgical correction of dorsal displacement of the soft palate.MethodsEach horse was assigned randomly to recover in either an illuminated (n = 15) or a darkened stall (n = 14). For pre-anesthetic medication, all horses received intravenous (IV) xylazine (0.4 mg kg⁻¹) and butorphanol (0.02 mg kg⁻¹). Anesthesia was induced with midazolam (0.1 mg kg⁻¹) and ketamine (2.2 mg kg⁻¹) IV and maintained on isoflurane in oxygen. Vital parameters, end-tidal CO₂ and isoflurane were recorded at 5-minute intervals. At the conclusion of anesthesia, horses were placed in either an illuminated or a darkened stall and xylazine (0.2 mg kg⁻¹) IV was administered at extubation. Video cameras were used to record the horses while they were allowed to recover undisturbed. Video recordings were later viewed and recoveries were evaluated on a 100-point scale by three graders.ResultsHorses in illuminated and darkened recovery stalls were evaluated on total anesthesia time, minimum alveolar concentration hours of isoflurane, time to first movement, time to standing, and total recovery score. There were no significant differences between the two groups in any of the measured parameters.ConclusionRecovering horses in a darkened versus an illuminated recovery stall may provide no benefit.Clinical relevanceDarkening the recovery stalls for horses recovering from general anesthesia may be unnecessary.     

The Effect of Hay Net Design on Rate of Forage Consumption When Feeding Adult Horses

Modern horse management systems tend to limit a horse's opportunity to forage. The objective of this experiment was to investigate the effect of hay net design on the rate of forage consumption when feeding horses. Eight adult horses were fed in individual stalls in a replicated Latin square design, with two horses per treatment per week. Horses were fed hay off the stall floor (control), or from one of three hay nets: large (15.2 cm openings), medium (4.4 cm openings), and small (3.2 cm openings). Horses had access to hay for two 4-hour periods each day. When horses could not consume all forage from the medium and small hay nets in 4 hours, a second study using a crossover design gave horses an unlimited amount of time to feed from the hay nets. Stopwatches were used to calculate time to consumption and dry matter intake rates (DMIR). Mean time to consumption was 3.1 and 3.4 hours for the control and large hay net, respectively, in study 1, and 5.1 and 6.5 hours for the medium and small hay nets, respectively, in study 2. Mean DMIR during the 4-hour feeding period were 1.5, 1.3, 1.1, and 0.9 kg/hr for the control, large, medium, and small hay nets, respectively; all treatments were different (P < .0001). These results demonstrate that hay nets were effective at decreasing the rate of forage consumption when feeding adult horses. Long-term studies are warranted to determine if horses will adapt to feeding from hay nets.     

Characterization of Influence of Manure Handling System and Feeding on the Level of Ammonia Release Using a Simple Method in Cow Houses

The effects of manure handling system and feeding of dairy cows were studied using a simple method to analyse the level of ammonia release in cow stables. Two ratios based on the balances of ammonia and sensible heat, and ammonia and carbon dioxide, respectively, in animal houses were determined and considered to give characteristic levels of the release of ammonia in relation to the animal density independently of the ventilation rate. This required measurements of ammonia, carbon dioxide and temperature with hand-held instruments in the buildings and in outside air. In total, 34 dairy herds were investigated in the south of Sweden. The results clearly demonstrated higher release of ammonia from free stall barn with liquid manure than from conventional tie stall barn with solid manure. There was a clear effect of the content of crude protein, gram per kg dry matter, in the total feed ration on ammonia release in tie stall barn with liquid manure.     

Relationship of equine housing to large airway inflammation

The pasture, as compared to stall confinement, has been considered a more desirable environment for maintaining the health of the respiratory system in the horse. This conclusion is based on reports which showed that ventilation in most barns was generally poor, and that horses bedded on straw and fed hay were exposed to many forms of respirable debris. In this study, six normal horses were evaluated for evidence of airway mucosal inflammation after being housed on pasture or stabled in a barn for one month. The response of the horses' airways was measured by assigning scores for the degree of tracheal mucosal secretions that were observed by endoscopic visualization. Cytological examination of transtracheal wash secretions was also performed, as well as histologic evaluation of tracheobronchial tissues obtained by a transendoscopic epithelial biopsy technique. Samples were collected at three time points; the initial collection occurred after the horses were housed on pasture for one month. The horses were subsequently moved to a barn for an equal length of time and samples were obtained at the end of this period. The horses were then returned to their original pasture and final sampling was performed after they were housed in this environment for two months. There were no significant changes in any of the parameters evaluated, regardless of the environment in which the horses were maintained. These findings indicate that housing horses in a barn for four weeks does not cause tracheobronchial mucosal inflammation in a manner that could be detected using the methods employed in this study.     

The effect of aerobic exercise after a period of inactivity on bone remodeling and calcium and phosphorus balance in mature horses

An experiment was conducted to determine the effect of aerobic training after a sedentary period on bone remodeling and Ca and P balance and serum concentrations in varying ages of mature horses. Eighteen stock-type geldings were blocked into three age groups (6 to 10, 11 to 15, and 16 and older years of age), within two groups of nine, with horses randomly assigned to one of two exercise treatments, exercised for 112 days (control) or idle for 56 days followed by 56 days of exercise (treated). Blood samples were taken at the beginning of period I and at 14-day intervals thereafter to determine serum concentrations of osteocalcin (OST), Ca, and P. Dorsal-palmar and lateral-medial radiographs were taken of the left third metacarpal bone on days 0, 56, 84, and 112 to monitor changes in bone density. Total fecal and urine collections were taken for 72 hours on days 0, 56, and 112. Mean serum OST concentrations were affected by treatment (P<.02), time (P<.001); and the interactions of treatment and age (P<.003), time and treatment (P<.001), and time, treatment, and age (P<.001). Overall dorsal (DBRAE), palmar (PRBAE), and medial (MRBAE) RBAE means were affected by time (P<.001), as was overall lateral (LRBAE) RBAE mean (P<.005). Overall DBRAE and PRBAE means were lower (P<.04) at day 56, and higher at day 84 (P<.02) and 112 (P<.001) as compared to day 0. Mean serum Ca concentration was affected by treatment (P<.003) and time (P<.001). Mean serum P concentration was affected by the interaction of time and treatment (P<.001). Mean apparent daily Ca balance was affected bythe interaction of time, treatment, and age (P<.03). Mean apparent daily P balance was affected by treatment (P<.02) and time (P<.001). Biochemical and radiographic data from this experiment suggest that bone remodeling as well as Ca and P balance and serum concentrations are affected by age, inactivity, and exercise in mature horses.     

Effect of Betamethasone and Exercise on Equine Carpal Joints With Osteochondral Fragments

Osteochondral fragments were created arthroscopically on the distal aspect of both radial carpal bones in 12 horses. On day 14 after surgery, one middle carpal joint of each horse was injected with 2.5 mL Betavet Soluspan (3.9 mg betamethasone sodium phosphate and 12 mg betamethasone acetate per milliliter) and the contralateral joint was injected with 2.5 mL saline as a control. Intra-articular treatments were repeated on day 35. On day 17, six horses began exercising 5 days per week on a high-speed treadmill. The other six horses were kept in box stalls throughout the study as nonexercised controls. On day 56, all horses were examined clinically and radiographically and then were euthanatized. Samples were obtained for histological, his-tochemical, and biochemical evaluation. Mild lameness was observed in five of the six exercised horses at day 56; four horses were lame in the control limb and one horse was lame in the treated limb. Of the five nonexercised horses evaluated for lameness, two were lame in the control limb, two were lame in the treated limb, and one was lame in both the control and the treated limb. No differences were noted on radiographs or palpation of steroid treated limbs versus control limbs. Firm reattachment of the osteochondral fragment to the radial carpal bone occurred in all but three joints. Gross cartilage damage was not different between steroid-treated joints and joints injected with saline. Histologically, there were no significant detrimental effects of betamethasone with or without exercise, but there was a tendency for more pathological change in treated joints. There was a trend toward decreased glycosaminoglycan staining in steroid treated joints of rested horses, whereas exercised horses had similar glycosaminoglycan staining in treated and control joints. No significant difference in the water content or uronic acid concentration was detected between treated and control joints. Intra-articular betamethasone administration in this carpal chip model was not associated with any significant detrimental effects in either rested or exercised horses.     

Comparison of recoveries from anesthesia of horses placed on a rapidly inflating-deflating air pillow or the floor of a padded stall

OBJECTIVE: To compare recoveries from anesthesia of horses placed on a conventional padded stall floor or on a specially designed air pillow. DESIGN: Prospective study. ANIMALS: 409 horses (> 1 year old) that were anesthetized for surgical procedures during a 37-month period. PROCEDURES: By random allocation, horses were allowed to recover from anesthesia in either a foammat-padded recovery stall or an identical recovery stall equipped with a rapidly inflating-deflating air pillow. All recoveries were videotaped for subsequent analysis by an independent evaluator. Times to first movement, first attempt to attain sternal recumbency, attainment of sternal recumbency, first attempt to stand, and successful standing were recorded. The numbers of attempts before achieving sternal recumbency and standing were counted, and scores for quality of standing and overall recovery were assigned. Recovery-related variables were compared between groups. RESULTS: Compared with horses allowed to recover in a conventional manner, horses that recovered from anesthesia on the air pillow had a significantly longer rest period before attempting to attain sternal recumbency and rise to standing. Once the pillow was deflated, horses were able to stand after significantly fewer attempts and the quality of their standing was significantly better. Between the 2 groups of horses, there was no significant difference in overall recovery quality scores. The air pillow and padded floor systems were equally safe. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that use of a rapidly inflating-deflating air pillow promotes a longer period of recumbency and a better quality of standing after anesthesia in horses.     

Evaluation of exclusive use of ivermectin vs alternation of antiparasitic compounds for control of internal parasites of horses.

A study for about a 30-month period was done to compare strongyle control programs, using per os treatments of ivermectin (IVE) paste exclusively or alternation of 4 antiparasitic paste compounds: IVE, oxfendazole (OFZ), oxibendazole (OBZ), or pyrantel pamoate (PRT). Every 8 weeks, 1 group of horses (barn C; n = 14 to 16) was given IVE paste exclusively, and a second group (barn E; n = 16) was given the 4 antiparasitic pastes on an alternating schedule. Worm eggs and larvae per gram of feces (epg and lpg, respectively) values were determined every 2 weeks during the investigation. This study in grazing horses (mares and fillies), naturally infected with internal parasites, was conducted during the period between Oct 22, 1987 and Feb 8, 1990, with an additional observation on Mar 28, 1990. For barn-C horses, treated exclusively with IVE (200 micrograms/kg of body weight) 14 times, 2-week posttreatment mean strongyle epg and lpg (small strongyle) values were reduced 99 to 100%. Mean strongyle epg and lpg (small strongyle) values for each 2-week sample period remained low (less than 20) throughout the study period, except for 1 moderate transient increase in July 1988. For the entire study period, the aggregate mean strongyle epg value was 12 and the lpg value was 6. Two-week posttreatment mean strongyle epg and lpg (small strongyle) values for barn-E horses, treated alternately with therapeutic (approx) dosage of IVE (200 micrograms/kg; 4 times), OFZ (10 mg/kg; 5 times), OBZ (10 mg/kg; 4 times), or PRT (6.6 mg base/kg; 2 times), varied within and between compounds.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of oral administration of lactulose in healthy horses

Lactulose (1-4-galactosidofructose) was administered to seven healthy, mature horses at a dosage of 333 mg/kg, by mouth, three times daily for 11 days. There was a significant (P<0.05) reduction in the concentration of blood ammonia during the period after first administration, with a mean reduction of 3 umol/L. Although fecal pH tended to increase after the administration of lactulose, the change was not statistically significant (P>0.05). There were no substantial changes in the results of physical examinations during the periods before, during and after administration in six horses. One horse developed signs of laminitis on the sixth day of administration, was removed from the study and responded well to treatment for laminitis.     

Gastric ulcer development in horses in a simulated show or training environment

OBJECTIVE: To determine whether conditions representing activities that are typical in the recreational use of horses, including transport to and from show grounds, stall confinement in unfamiliar surroundings, and light exercise, are associated with increased incidence of gastric ulcers in horses. DESIGN: Randomized controlled study. ANIMALS: 20 client-owned horses. PROCEDURE: Horses had no gastric ulcers as determined by endoscopic examination on study day -1. Ten control horses were maintained on-site with no changes in management variables. Ten horses were transported via trailer for 4 hours on day 0 to another site, placed in individual stalls, fed twice daily, and exercised twice daily for 3 days. On day 4, they were transported back to the original site via trailer for 4 hours. On day 5, endoscopic examinations were performed on all horses to assess gastric mucosa status. RESULTS: Horses that were transported and housed off-site had a significantly higher incidence of hyperkeratosis and reddening of the gastric mucosa than control horses. Two control horses and 7 transported horses developed gastric ulcers by day 5. Ulcer scores of transported horses increased significantly from day -1, whereas ulcer scores in control horses did not change significantly from day -1. CONCLUSIONS AND CLINICAL RELEVANCE: Activities that are typical in recreational use of horses were ulcerogenic, and ulcers in the gastric squamous mucosa can develop under these conditions within 6 days.     

Effects of a rubber-slatted flooring system on cleanliness and foot health in tied dairy cows

Effects on animal cleanliness and foot health of a new rubber-slat system for tied dairy cows, with the ability to drain faeces and urine, were studied in a 2-year controlled quasi-randomised trial in a Swedish university herd. Swedish Red and White cows were kept tied in 42 traditional long-stalls with rubber mats. In total, 82 cows were observed. In 21 stalls, the rearmost 0.74m of the solid stall floor was replaced with nine rubber-coated 53mm wide slats, divided by 29mm slots. The cleanliness was assessed subjectively weekly (year 1) or bi-weekly (year 2) by observations of the hind part of the body. Claw measurements and foot health in hind feet were assessed in connection with hoof trimmings at the beginning, middle and end of the housing period. The foot-health recordings were blinded to flooring. For the analysis of both cleanliness (1781 records, 73 cows) and foot health (240 records, 79 cows), logistic regression was applied, using marginal models and cow observations as repeated measures within each year. The risk of getting dirty on the rubber-slatted floor was significantly lower (odds ratio 0.12 for hind feet when short stall dividers were used, 0.39 for hind legs and 0.38 for thighs and udder), comparing with the solid stall floor. The prevalence of foot diseases in hind feet at trimming was significantly lower on the rubber slats (odds ratio 0.23 for dermatitis, 0.09 for heel horn erosion, and 0.34 for sole ulcer or sole or white line haemorrhage).     

Changes in the third metacarpal bone and frequency of bone injuries in young quarter horses during race training - observations and theoretical considerations

Fifty-three Quarter Horses were put into race-training at 18 mo of age. Changes in the third metacarpal were monitored by radiographic densitometry initially at 83 days prior to the commencement of training and at days 0, 62, 104 and 244 of training. A normal increase in density of the third metacarpal due to growth and mineralization was seen from the first set of radiographs until the horses began training at day 0 (P<.001). Bone density then decreased to day 62 (P<.001), remained low through day 104 before it began to increase to day 244 (P<.005). Differences in the most optically dense portion of each cortex of the third metacarpal were compared in horses completing the study without injury and those sustaining a bone-related injury. Horses experienced fewer injuries when they had greater cortical mass in the lateral (P<.05) and medial (P<.1) aspects of the third metacarpal, relative to the palmar aspect, at the commencement of training.     

环境因素对散养奶牛的繁殖行为和繁殖性能的影响

1991～1994年在洛阳市奶牛场连续观察散养与栓系饲养体制下奶牛的发情表现、发情地点及每日的发情时间分布，统计每月的受胎率和奶牛的产后首次配种时间。结果表明，在散放饲养条件下，奶牛发情明显，发情行为期长；夏、冬季的受胎率低于春、秋季，明显地受温度的影响和五项气象因素的综合作用；五项气象因素对产后首次配种时间的综合影响显著。     

Short-duration exercise and confinement alters bone mineral content and shape in weanling horses

The hypothesis that short-duration exercise may ameliorate the decrease in bone mass observed with confinement was investigated with 18 quarter horses (nine colts and nine fillies) weaned at 4 mo of age and placed into box stalls. After a 5-wk adjustment period, individuals were grouped by age and weight, and then divided randomly into three treatment groups: 1) group housed; 2) confined with no exercise; and 3) confined with exercise. The confined and exercised groups were housed in 3.7 m x 3.7 m box stalls for the 56-d duration of the trial. The exercised group was sprinted 82 m/d, 5 d/wk, in a fenced grass alleyway. The weanlings were led down an alleyway, turned loose in a small pen, and then released and allowed to run back down the alley. The group horses were housed together in a 992-m2 drylot with free access to exercise. On d 0, 28, and 56, dorsopalmar and lateromedial radiographs of the left third metacarpal bone were taken to estimate changes in bone mineral content and cortical widths. Mean values of medial, lateral, and total radiographic bone aluminum equivalence increased over time (P < 0.05), whereas dorsal and palmar radiographic bone aluminum equivalence did not change significantly. Dorsal, medial, and total radiographic bone aluminum equivalence tended (P = 0.09) to differ by a treatment x day interaction, with values increasing over time only in the exercised group. Normalized medial and total radiographic bone aluminum equivalence tended (P < 0.1) to differ (P < 0.01) with treatment, with exercised horses having greater bone aluminum equivalence than confined horses. Dorsopalmar cortical width in exercised horses was greater than on d 56 (treatment x day; P = 0.07). The dorsopalmar medullary cavity decreased in exercised vs. group-housed horses (P = 0.027), whereas dorsal and medial cortical width tended to increase only in the exercised horses (treatment x day; P < 0.01). This study indicated that a short-duration exercise protocol might be effective in improving bone mass and therefore skeletal strength in horses.     

Local airborne particulate concentration is associated with visible tracheal mucus in Thoroughbred racehorses

Reason for performing study: Accumulations of tracheal mucus assessed by endoscopic examination are associated with poor performance in racehorses. The air quality in horses' stalls may contribute to this visible tracheal mucus. Objectives: To determine whether the concentration and number of airborne particulates in stalls are associated with visible accumulations of tracheal mucus and with the number of inflammatory cells in tracheal aspirates. Methods: We studied 107 racehorses from 3 stables, in 3 different months, and measured airborne particulate matter 3 times daily in each of the stalls. On each monthly visit, horse airways were examined endoscopically and assigned a mucus score, and tracheal lavage was performed. Bivariate procedures, general estimating equations and linear mixed models were applied to estimate the association between PM and the presence of accumulations of mucus and number of inflammatory cells. Results: Stable, stall, month and PM were all significantly associated with the presence of accumulations of tracheal mucus, which had an overall prevalence of 67%. The odds of horses having visible accumulation of mucus were increased when horses occupied enclosed stables or stalls with higher particulate concentrations, and when concentrations of larger particles (≤10 µm in diameter) were elevated. Sixty‐eight percent of tracheal wash samples contained more than 20% neutrophils. Increased numbers of neutrophils were associated with the concentration of smaller particles (≤2.5 µm in diameter). Potential relevance: Careful consideration of stable construction and management practices focused on maintaining the lowest possible dust concentrations throughout the day should reduce the prevalence of visible accumulations of tracheal mucus, potentially improving racing performance.