Bacterial culture of septic synovial structures of horses: Does a positive bacterial culture influence prognosis?

Reasons for performing study: The influence of synovial fluid culture on short‐ and long‐term prognosis of cases with septic synovitis requires study. Hypotheses: Horses with a positive bacterial culture from septic synovial fluid are less likely to survive or return to successful athletic function than those with a negative bacterial culture from septic synovial fluid. Methods: Records of mature horses presented to 2 equine referral hospitals for investigation of suspected septic synovitis were examined. Horses (n = 206) were included in the study if synovial fluid was submitted for full laboratory examination, including bacterial culture. A diagnosis of septic synovitis was based on a nucleated cell count >30 × 10⁹ cells/l or >90% neutrophils and other clinical, cytological and bacteriological parameters. Long‐term follow‐up was obtained by telephone questionnaire. Univariate analysis, using the Fisher's exact test, was used for all outcomes. Results: Fourteen (20.9%) of 67 horses with a positive bacterial culture from synovial fluid were subjected to euthanasia because of persistent synovial sepsis compared to 2 (1.44%) of 139 with negative bacterial cultures (P<0.001). Overall survival and successful long‐term return to function in horses with a positive bacterial culture was 50% (24/48 horses) compared to 70.5% (74/105) in culture negative horses (P = 0.01). In horses that survived to be discharged, successful long‐term return to function was not significantly different between culture positive and culture negative groups. Growth of Staphylococcus aureus from synovial fluid did not affect short‐term survival to discharge from the hospital compared to other positive bacterial culture; however, successful long‐term return to function was only 30.4% (4/13) in horses from which S. aureus was cultured compared to 73.9% (17/23) of horses in which other bacteria were cultured (P = 0.015). Conclusions and potential clinical relevance: Horses with a positive bacterial culture from a septic synovitis have a poorer prognosis for survival to discharge from hospital and overall long‐term return to function than horses that yielded no bacterial growth. When S. aureus was cultured, the long‐term prognosis was poorer.     

Pharmacokinetics and local tolerance of cefovecin sodium after intra‐articular administration in horses

Searching for new therapeutic options against septic arthritis in horses, this research was focused on the study of the kinetics and local side effects after the intra‐articular treatment of horses with cefovecin sodium. A single dose (240 mg) of the drug (Convenia^®) was administered into the radiocarpal joint of adult healthy horses (n = 6), and drug concentrations in plasma and synovial fluid were determined by high‐performance liquid chromatography (HPLC). Local tolerance was also studied based on the modification of different joint physiopathological parameters (pH, cellular, and protein concentration in synovial fluid). Although no clinically relevant joint damage was noticed, significant increases in the protein concentrations at 5 min and in the cellular concentration at 30 min after cefovecin administration were observed in the treated radiocarpal joints. The duration of the cefovecin above the minimal inhibitory concentration (MIC) ≤1 μg/mL was 28.80 ± 2.58 h in the radiocarpal joint and 16.00 ± 2.86 h in plasma. The results of this study showed that intra‐articular administration of cefovecin sodium in horses could be considered in the future to manage septic arthritis in horses, as it offers a good pharmacokinetic behavior and good local tolerance.     

Safety and efficacy of subcutaneous alpha-tocopherol in healthy adult horses

Vitamin E is essential for neuromuscular function. The primary treatment, oral supplementation with natural (‘RRR’) α-tocopherol, is not effective in all horses. The objectives of this pilot study were to evaluate the safety and efficacy of a subcutaneously administered RRR-α-tocopherol preparation. Horses were randomly assigned in a cross-over design to initially receive RRR-α-tocopherol (5000 IU/450 kg of 600 IU/mL) subcutaneously (n = 3) or orally (n = 3) or were untreated sentinels (n = 2). Tissue reactions following injection in Phase I of the study necessitated adjustment of the preparation with reduction of the RRR-α-tocopherol concentration to 500 IU/mL in Phase 2. Following an 8-week washout period, horses received the reciprocal treatment route with the new preparation (5000 IU/450 kg of 500 IU/mL). Serum, CSF and muscle α-tocopherol concentrations were determined by high-performance liquid chromatography over a 14-day period during each phase. Serum and CSF α-tocopherol concentrations increased significantly postinjection only when the 500 IU/mL product was administered (P<0.0001). There was no significant difference in the muscle concentration of α-tocopherol following either treatment. All eight horses had marked tissue reaction to subcutaneous injection, regardless of product concentration. Whilst we have demonstrated that this route may be a useful alternative to oral supplementation, the marked tissue reaction makes use of such products limited at this time to only the most refractory of cases.     

Equine duodenal motility,assessed by ultrasonography,as a predictor of reflux and survival following colic surgery

Intestinal dysmotility following equine colic surgery contributes negatively to financial and prognostic outcomes. This study assessed duodenal contractility as a predictor of post-operative reflux and survival to discharge in horses following colic surgery. Duodenal contractility was assessed using daily transabdominal ultrasound examinations in 49 horses for up to 7 days (Day 1 scan performed between 6 and 36 h post-surgery and sequential daily scans performed between 08.00 and 20.00 h) following colic surgery (September 2014–April 2017). The duodenum was visualised ventral to the right kidney, and duodenal contractions were measured over 2 min. The signalment of each horse and surgical findings were noted. Outcomes were defined as horses that refluxed (>5 L/24 h beyond 24 h) or did not reflux post-operatively and those that were survivors or were nonsurvivors. A significant difference in duodenal contractions at Day 1 post-operatively was identified between horses that refluxed (n = 8) and those who did not reflux (n = 32; P = 0.013) but not between those who were nonsurvivors (n = 7) and survivors (n = 32; P = 0.113). Horses in the reflux group had reduced duodenal contractility comparatively. There were no significant differences in duodenal contractions in the sequential days after the Day 1 scan or between duodenal contractions and surgical findings. A significant association was identified between duodenal contractions and survivors (P = 0.039; odds ratio 1.88). The main study limitations were the single centre design with consequent small numbers of horses included. The study did not account for other factors that may contribute to alterations in motility such as drug administration or stages of re-feeding. This preliminary study indicates that Day 1 (6–36 h post-operatively) duodenal contractions may predict reflux (>5 L/24 h beyond 24 h) and that increased duodenal contractions are associated with survival. However, there was no clear distinction or cut-off between groups. Future studies with greater numbers of horses yielding better statistical power are required.     

Atypical myopathy in the South-East of England: Clinicopathological data and outcome in hospitalised horses

This retrospective case series describes clinicopathological data and outcome of hospitalised atypical myopathy (AM) cases in the South-East of England. The study aimed to describe the frequency of metabolic abnormalities (hyperglycaemia, hyperlactataemia, hypertriglyceridaemia) and outcome in AM cases in the South-East of England and test the hypothesis that serum creatine kinase (CK) activity and blood glucose, lactate and triglyceride concentrations are associated with outcome. Medical records (2011–2017) from three referral hospitals were reviewed for cases with a clinical diagnosis of AM. A previously described algorithm was applied and cases were included if a diagnosis of AM was considered highly likely. In cases admitted after 2013 known or possible exposure to sycamore trees was also required for inclusion. Sixty-four animals were included, 44% (28/64) survived. Hyperglycaemia, hyperlactataemia and hypertriglyceridaemia were present in 76%, 89% and 92% of horses on admission, respectively. Survivors had lower blood lactate concentrations (survivors: median 3.5 mmol/L; range 0.5–10.4 mmol/L vs. nonsurvivors: median 7.3 mmol/L; range 2.5–16.5 mmol/L; P = 0.011) and serum CK activities (survivors: median 38,369 U/L; range 7024–570,498 U/L vs. nonsurvivors: median 172,687 U/L; range 2036–570,953 U/L; P = 0.027) on admission when compared to nonsurvivors. Increasing CK activity (P = 0.008) and triglyceride concentrations (P = 0.038) during hospitalisation were associated with nonsurvival. More nonsurvivors required sedation (18/29; 62.1% vs. 4/22; 18.2%; P = 0.002). The prognosis for hospitalised horses with AM is guarded and outcome in this population was associated with admission CK activity and lactate concentrations, and increasing CK activity and triglyceride concentrations and need for sedation during hospitalisation.     

Body weight and range usage affect net energy utilisation in commercial free-range laying hens when evaluated in net energy chambers

Within a given free-range flock, some hens prefer to spend the majority of their time in the shed (stayers), while others frequently access the range (rangers). Laying performance has been associated not only with the development of these sub-populations but also with different body weights (BW). The purpose of this study was to determine if range usage, BW or a combination of both is associated with energy metabolism and as such contribute to improved hen performance. Forty-eight Lohmann Brown hens at 74 wk of age were selected from a commercial free-range farm based on their BW and range usage over a 56-week period. Using a 2 × 2 factorial arrangement, hens were either classified as heavy (mean ± SEM; 2.01 ± 0.02 kg, n = 24) or light (1.68 ± 0.01 kg, n = 24), and also classified as rangers (accessed the range for 84.1% of available days, 242 ± 3.75 d; n = 24) or stayers (accessed the range for 7.17% of available days; 23.4 ± 6.08 d, n = 24). Stayers had significantly higher metabolizable energy (ME) intake per metabolic BW per d (0.852 vs. 0.798 MJ/kg BW^0.75 per d; P = 0.025), higher heat production (0.637 vs. 0.607 MJ/kg BW^0.75 per d; P = 0.005), higher heat increment (0.267 vs. 0.237 MJ/kg BW^0.75 per d; P = 0.005) and retained more nitrogen (1.59 vs. 1.46 g/hen per d; P = 0.023) compared to the rangers. Light hens had significantly higher metabolic energy intake per metabolic BW (0.854 vs. 0.796 MJ/kg BW^0.75 per d; P = 0.018), net energy (NE) intake (0.595 vs. 0.551 MJ/kg BW^0.75 per d; P = 0.032), and retained energy (0.225 vs. 0.181 MJ/kg BW^0.75 per d; P = 0.032), as well as lower heat production (0.936 vs. 1.003 MJ/hen per d; P = 0.002) compared to heavier hens. An interaction was observed across levels of analysis i.e. between light stayers and light rangers. The light rangers had significantly higher NE intake compared to the light stayers (9.77 vs. 9.27 MJ/kg BW^0.75 per d; P = 0.024). In conclusion, light hens were more energy efficient compared to heavy hens. Moreover, light rangers had a more efficient feed utilisation compared to the light stayers.     

Crooked tail carriage in horses: Increased prevalence in lame horses and those with thoracolumbar epaxial muscle tension or sacroiliac joint region pain

The relationship between lameness and crooked tail carriage (CTC) in horses is unclear. The objectives of this study were (i) to determine the association between CTC and lameness; (ii) among lame horses, to determine associations between CTC and lameness diagnosis, saddle slip, thoracolumbar range of motion (ROM), epaxial muscle tension and pain, and sacroiliac joint region (SIJR) pain, and (iii) to determine whether abolition of lameness and SIJR pain by diagnostic anaesthesia modified CTC. In this study, 520 lame and 170 nonlame sports horses were examined for CTC and other characteristics by one clinician (S.J.D.). All horses were evaluated when ridden. Lame horses were also assessed in hand and on the lunge. Crooked tail carriage, its direction, lameness, musculoskeletal and tack-related parameters were recorded as binary variables and analysed using 2 × 2 contingency tables. Sacroiliac joint region pain was diagnosed using local anaesthesia. Standard errors are shown in square brackets. 32.5% of lame horses had CTC, compared with 5.3% of nonlame horses (odds ratio = 8.6 [confidence intervals 4.4, 16.7]; P = 2×10⁻¹²). Of 169 lame horses with CTC, 103 (60.9% [3.8%]) held their tail to the left. There was no association between the side of the predominant lame limb and CTC direction. However, CTC was more common (P = 0.005) in horses with hindlimb lameness (35.7% [2.4%], N = 401) compared with forelimb lameness (21.0% [4.1%], N = 100). Crooked tail carriage was associated with SIJR pain (P = 0.0007) and thoracolumbar epaxial muscle tension (P = 0.0007), but not with saddle slip, reduced thoracolumbar ROM or thoracolumbar epaxial muscle pain. Limitations of the study included the facts that nonlame horses were a convenience sample and lameness assessment, other clinical observations and determination of the presence of CTC were subjective, with potential for bias. Video recordings and photographs are available for verification of tail position. It was concluded that CTC is more prevalent in lame horses than nonlame horses. There is a positive association between CTC and hindlimb lameness, SIJR pain and thoracolumbar epaxial muscle tension.     

Di-tri-octahedral smectite for the prevention of post-operative diarrhea in equids with surgical disease of the large intestine: Results of a randomized clinical trial

The aim of this study was to evaluate the effects of a commercially available di-tri-octahedral (DTO) smectite product on clinical signs and prevalence of post-operative diarrhea in horses with colic associated with disease of the large intestine. Sixty-seven horses with surgical disease of the large intestine were randomly assigned to be treated with DTO smectite (n = 37; 0.5 kg via nasogastric intubation every 24 h for 3 days post-operatively) or a placebo (n = 30). The effect of treatment on fecal scores and clinical and hematological parameters, including heart rate, mucous membrane color, temperature, total white blood cell count, total neutrophil count and total plasma protein values, were determined.Horses treated with DTO smectite had a significant reduction in the prevalence of post-operative diarrhea (10.8%), compared with controls (41.4%). A significant improvement in mucous membrane color was observed 72 h post-operatively in horses receiving treatment, compared with placebo. Administration of DTO smectite to colic patients with disease of the large intestine reduced the occurrence of diarrhea in the early post-operative period.     

Benefits and risks of barefoot harness racing in Standardbred trotters

There is a lack of research on the benefits and risks of shoeing conditions in harness racing. Thus, our objectives were to: (a) investigate whether velocity times (VT; s/km) are affected by racing unshod (N = 76,932 records on 5,247 horses); (b) determine the potential risks of galloping, being penalized, and disqualification when competing unshod (N = 111,755 records on 6,423 horses); and (c) identify additional environmental factors that affect VT and risks. VT was found to be significantly influenced by shoeing condition (e.g., unshod, shod front, shod hind, or fully shod), but also by sex, age, season, track, track condition, start method, start position, distance, and driver‐horse performance level (p < 2e‐16). The risks of galloping and disqualification were significantly influenced by shoeing condition, sex, age, season, track, start method, start position, or driver‐horse performance level (p ≤ .05). Horses racing unshod had 0.7 s/km lower VT than fully shod horses and showed better performance when racing on neutral tracks during the late summer than horses with other shoeing conditions during the same period. However, racing unshod increased the relative risks of galloping and disqualification by 15%–35% in all seasons. Horses shod only on the hind hooves showed better performance than fully shod horses, without higher risks associated with competing unshod.     

Ethylenediaminetetraacetic acid (EDTA) anticoagulant affects the refractometric measurement of total protein concentration in equine synovial fluid

The objectives of this study were to (i) determine the effect of ethylenediaminetetraacetic acid (EDTA) concentration on the refractometric measurement of the total protein (TP) concentration of equine synovial fluid and (ii) assess the effect of time and temperature on the refractometric measurement of TP concentration. Synovial fluid was retrieved aseptically from horses presenting to Liphook Equine Hospital either (a) immediately after euthanasia or (b) from those requiring arthrocentesis as part of their clinical investigation. Samples were aliquoted into commercially available (i) plain tubes (0.5 mL; control) and (ii) EDTA tubes (at different volumes to obtain serial dilutions of EDTA:synovial fluid). TP concentration was measured by two independent observers using a calibrated hand-held refractometer. Samples from a separate group of horses were stored for 24 h at 4°C and 20°C before analysis to assess the effects of time and temperature. Results were compared using repeated measures ANOVA. TP concentration was significantly higher at all EDTA concentrations compared to control samples, with the greatest effect seen with higher concentrations (P<0.0001 for samples with ≥3.17 mg EDTA/mL). Storage time or temperature did not significantly affect TP concentration. Refractometric measurement of small volumes of synovial fluid in commercially available EDTA tubes leads to artificially elevated TP concentrations. Delays in sample analysis and alterations in storage conditions did not significantly affect TP concentration within the parameters studied. The magnitude of overestimation of synovial total protein concentration could result in misclassification of suspect synovial sepsis cases where EDTA tubes are used.     

Antioxidant and haematological biomarkers in different groups of horses supplemented with polyunsaturated oil and vitamin E

Oxidative stress has been correlated with pathologies that impair the performance of athlete horses. The aim of this study was to assess the effects of supplementation with a mixture of polyunsaturated oil and vitamin E on the antioxidant and haematological biomarkers of horses. Horses under maintenance care (n = 6) and horses in training (n = 10) received 100 and 300 ml of the oil mixture respectively. Supplementation was provided for a period of 8 weeks, together with isocaloric inclusion. Blood samples were collected at three time periods (pretest, after 4 weeks and after 8 weeks) to analyse the following: the red blood cell count (RBCc); haemoglobin (Hb); haematocrit (HT); leucocytes; lymphocytes; platelets; the mean corpuscular volume (MCV); the mean corpuscular haemoglobin concentration (MCHC); the standard deviation of the red blood cell distribution width (RDW‐SD); the coefficient of variation of the red blood cell distribution width (RDW‐CV); glutathione peroxidase (GPx); superoxide dismutase (SOD); uric acid (UrAc); total plasma proteins (TPP); and creatine kinase (CK). After the 8 weeks of supplementation, animals under maintenance care exhibited significant increases in SOD, UrAc, the white blood cell count (WBCc), the RDW‐SD and the RDW‐CV (p < 0.05). The animals in training exhibited increases in GPx, SOD and UrAc (p < 0.05). In conclusion, supplementation with polyunsaturated oil and vitamin E increases blood antioxidants among animals under maintenance and in training, with different trends, while contributing to the fight against oxidative stress in each group analysed.     

Nitrogen Retention and Plasma Amino Acid Responses in Mature Geldings Fed Three Dietary Concentrations of Lysine

Six mature Quarter Horse geldings (age, 11.5 ± 4.7 years; body weight [BW], 526 ± 9.2 kg) were used in a replicated 3 × 3 Latin square design to determine the effects of three dietary lysine (Lys) levels on nitrogen (N) retention and plasma amino acid (AA) concentrations. The geldings were fed a basal diet of concentrate and Bermuda grass hay supplemented with synthetic essential amino acids (EAA) to meet estimated requirements for EAA. Geldings were fed one of three dietary treatments: (1) a basal diet deficient in Lys (L−; 0.027 g of Lys•kg⁻¹ BW•d⁻¹); (2) a basal diet supplemented with synthetic Lys to meet National Research Council (NRC; 2007) requirements (L+; 0.036 g of Lys•kg⁻¹ BW•d⁻¹); or (3) a basal diet supplemented at twice the recommended Lys requirement (2 × L; 0.070 g Lys•kg⁻¹ BW•d⁻¹). Horses fed the 2 × L diet had higher N intakes (P = .0056) than horses fed either the L− or L+ diet. However N retention (P = .63) was not different between treatments. Plasma Lys was greater (P < .0001) in 2 × L than L− and L+ diets. Plasma threonine (Thr; P < .01), methionine (Met; P = .03), and total plasma non-EAA (P < .05) concentrations decreased as dietary Lys increased. These results suggest N retention is not a good response criterion for evaluating the AA requirements of mature horses. However, plasma AA data indicated more efficient use of Thr and Met when horses were fed dietary Lys in concentrations greater than the current requirement recommended by the Nutrient Requirements of Horses (National Research Council, 2007).     

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.     

Evaluation of peritoneal fluid pH, glucose concentration, and lactate dehydrogenase activity for detection of septic peritonitis in horses

OBJECTIVE: To determine whether peritoneal fluid pH, glucose concentration, and lactate dehydrogenase activity can be used to differentiate horses with septic peritonitis from those with nonseptic peritonitis. DESIGN: Prospective study. ANIMALS: 46 horses, including 10 healthy horses, 15 horses with septic peritonitis, and 21 horses with nonseptic peritonitis. PROCEDURE: Peritoneal fluid and blood samples were analyzed for pH, glucose concentration, and lactate dehydrogenase activity. Complete blood cell counts were performed, and peritoneal fluid samples were submitted for bacterial culture. RESULTS: Horses with septic peritonitis had significantly lower peritoneal fluid pH and glucose concentrations than horses with nonseptic peritonitis and healthy horses. Compared with other tests, serum-to-peritoneal fluid glucose concentration differences > 50 mg/dl had the highest diagnostic use for detection of septic peritonitis. Peritoneal fluid pH < 7.3, glucose concentration < 30 mg/dl, and fibrinogen concentration > 200 mg/dl were also highly indicative of septic peritonitis. CLINICAL IMPLICATIONS: Peritoneal fluid pH and glucose concentration can be used to assist in the identification of horses with septic peritonitis. These measurements can provide an early indication of sepsis, especially if cytologic evaluation of peritoneal fluid is unavailable or results are equivocal and peritoneal fluid bacterial culture results are pending.     

Application of a Ridden Horse Pain Ethogram to horses competing at 5-star three-day-events: Comparison with performance

A Ridden Horse Pain Ethogram (RHpE) was previously developed to facilitate the detection of musculoskeletal pain. The objectives were to apply the RHpE during warm-up for the dressage phase of two 5* three-day events and to correlate the RHpE scores with subsequent performance. It was hypothesised that there would be a higher rate of failure to complete the cross-country phase in horses which exhibited ≥7 behaviours compared with those showing <7 behaviours. The RHpE, comprising 24 behaviours, was applied for 10–12 min during warm-up. Gait abnormalities in trot and canter were recorded. Dressage penalties, cross-country performance, showjumping penalties and final placings were documented. Horses were categorised as those which completed cross-country, or those which did not complete because of elimination or retirement. RHpE scores (n = 137) ranged from 0 to 9/24 (median 3 [range 0–9] for nonlame horses; median 5 [range 1–9] for horses with gait abnormalities in trot or canter). There was a moderate correlation between dressage penalty scores and the RHpE score (rho = 0.4, P<0.001, Spearman rank). Fifty-nine per cent of horses (n = 10/17) with a RHpE score ≥7 failed to complete cross-country, compared with 33% (n = 39/117) with a score <7. Horses that failed to complete the cross-country phase had higher RHpE scores compared with those that completed (P = 0.04, W = 8.3, Kruskal–Wallis; pairwise comparison Bonferroni, P = 0.06). There was a significant (rho = 0.3) relationship between total RHpE score and final horse placings (n = 80, P<0.01, Spearman rank). Horses with lameness or gait abnormalities in canter had significantly higher RHpE scores (P<0.01, χ² = 35, chi-square test) compared with other horses. There was a strong correlation between the RHpE scores for horses which competed at both events (P<0.001, rho = 0.6, Spearman rank). The RHpE should facilitate earlier identification of horses which may benefit from diagnosis and treatment, resulting in improvement in both performance and equine welfare.     

Effects of detomidine or romifidine during maintenance and recovery from isoflurane anaesthesia in horses

ObjectiveTo evaluate the effects of detomidine or romifidine on cardiovascular function, isoflurane requirements and recovery quality in horses undergoing isoflurane anaesthesia.Study designProspective, randomized, blinded, clinical study.AnimalsA total of 63 healthy horses undergoing elective surgery during general anaesthesia.MethodsHorses were randomly allocated to three groups of 21 animals each. In group R, horses were given romifidine intravenously (IV) for premedication (80 μg kg^–1), maintenance (40 μg kg^–1 hour^–1) and before recovery (20 μg kg^–1). In group D2.5, horses were given detomidine IV for premedication (15 μg kg^–1), maintenance (5 μg kg^–1 hour^–1) and before recovery (2.5 μg kg^–1). In group D5, horses were given the same doses of detomidine IV for premedication and maintenance but 5 μg kg^–1 prior to recovery. Premedication was combined with morphine IV (0.1 mg kg^–1) in all groups. Cardiovascular and blood gas variables, expired fraction of isoflurane (Fe′Iso), dobutamine or ketamine requirements, recovery times, recovery events scores (from sternal to standing position) and visual analogue scale (VAS) were compared between groups using either anova followed by Tukey, Kruskal-Wallis followed by Bonferroni or chi-square tests, as appropriate (p < 0.05).ResultsNo significant differences were observed between groups for Fe′Iso, dobutamine or ketamine requirements and recovery times. Cardiovascular and blood gas measurements remained within physiological ranges for all groups. Group D5 horses had significantly worse scores for balance and coordination (p = 0.002), overall impression (p = 0.021) and final score (p = 0.008) than group R horses and significantly worse mean scores for VAS than the other groups (p = 0.002).Conclusions and clinical relevanceDetomidine or romifidine constant rate infusion provided similar conditions for maintenance of anaesthesia. Higher doses of detomidine at the end of anaesthesia might decrease the recovery quality.     

Evaluation of pleural and peritoneal effusions

Certain diseases cause an increase in the amount of fluid present in the pleural and/or peritoneal cavity (an effusion). Uroperitoneum subsequent to kidney, ureter, bladder, or urethra rupture also can cause an increased amount of fluid in the abdomen. Evaluation of fluid samples often is helpful in identifying the mechanism causing the effusion and, occasionally, results in a specific diagnosis. The TP, TNCC, and general cytologic examination can be performed easily, quickly, and inexpensively in-house. The TP and TNCC are used to classify effusions as transudates, modified transudates, or exudates. Transudates usually are caused by hypoalbuminemia, but also can be caused by leakage of fluid from efferent intestinal lymphatics. Cytology and culture usually are not rewarding in the evaluation of transudates. Modified transudates usually are caused by increased vascular permeability or increased intrahepatic hydrostatic pressure. Cytologic and radiographic examinations often are helpful in evaluating patients with modified transudates, while cultures usually are unrewarding. The exudate class encompasses the inflammatory exudates (septic or nonseptic), neoplastic exudates, and chylous effusions. Inflammatory exudates have a high TP and predominantly contain inflammatory cells. They may be septic or nonseptic. When septic, degeneration neutrophils often, but not always, are found. Cultures often are needed to determine whether sepsis is present, to identify the specific organism, and to determine the best therapy. Neoplastic exudates may contain numerous neoplastic cells. If there is concern that the cells are dysplastic instead of neoplastic, the cytology preparation should be referred to a consultant. Chylous effusions usually contain many small lymphocytes with a variable number of neutrophils and macrophages. In chronic chylous effusions, however, neutrophils and/or macrophages may predominate. Chylous effusions usually are differentiated easily from pseudochylous effusions by cytology. Comparison of fluid and serum triglyceride and cholesterol concentrations can be used to differentiate chylous and pseudochylous effusions when differentiation cannot be accomplished by cytology.     

Effect of dietary cation-anion difference on mineral balance, serum osteocalcin concentration and growth in weanling horses

Sixteen Quarter Horse weanlings were used in a splitplot design experiment to determine the effects of dietary cation-anion difference (DCAD) on mineral metabolism, osteocalcin concentration and variables of growth. Horses were blocked by age and sex and then randomly allotted to two treatment groups (High or Low). Experimental diets with a DCAD of +325 (High, H) and −52 (Low, L) were formed by supplementing diet H with sodium bicarbonate and diet L with calcium chloride. The DCAD was calculated as meq (Na+K)−(Cl+S)/kg of diet DM. The 25-week trial consisted of three 72 h collection periods at 150, 240 and 330 d of age during which a complete urine collection was taken.Multiple fecal grab samples were collected to represent every 2 h post-feeding during each collection period. Venous blood samples were taken for analysis of serum osteocalcin concentration. Weekly measurements were taken to monitor skeletal growth. Representative samples of feed, feces and urine were analyzed for mineral content and apparent mineral balances were calculated by difference. Although osteocalcin concentration did not differ significantly between diets H and L at 150 and 330 d of age, it was higher (P<.05) at d 240 in horses consuming diet H versus diet L. No difference (P>.05) was detected between treatments in any skeletal growth variable measured. Phosphorus balance and digestibility did not differ significantly between treatments across d of age. However, digestibility of P was lower (P<.05) at d 240 and 330 compared to d 150 in both treatments. Horses consuming diet L experienced an increased (P<.05) urinary and a decreased (P<005) fecal excretion of Ca compared to horses consuming diet H. Apparent daily Ca balance was higher (P<.05) in horses consuming diet L than those on diet H at 240 and 330 d of age. Furthermore, Ca digestibility decreased significantly between d 150 and d 240 and 330 in horses consuming diet H. Horses consuming diet L experienced no difference (P>.05) in Ca digestibility across d of age.These findings suggest that horses consuming a low DCAD diet are able to compensate for the increased urinary excretion of Ca by enhancing intestinal Ca absorption and thereby increasing daily CA balance and digestibility.