Luis M. Rubio-Martínez

Clinical use of antimicrobial regional limb perfusion in horses: 174 cases (1999–2009)

OBJECTIVE To describe the clinical use of regional limb perfusion with antimicrobials (A-RLP), complications, and outcome in a large series of patients. DESIGN Retrospective case series. ANIMALS 174 horses. PROCEDURES Medical records of horses treated with A-RLP between 1999 and 2009 were reviewed. Signalment, primary complaint, horse use, etiology, duration of clinical signs, previous treatment, structures involved, concurrent conditions, A-RLP characteristics, additional treatments, complications, and outcome were recorded. At long-term follow-up, 2 outcomes were investigated: survival rate and return to previous use at the same or higher level. Univariate and multivariate logistic regression analyses were conducted. RESULTS Group 1 (96 horses) included septic synovitis. Group 2 (50 horses) included extrasynovial lacerations (23 horses) and fresh, minimally contaminated intrasynovial lacerations without evidence of established synovial infection (27 horses). Group 3 (28 horses) included miscellaneous other conditions. Only minor complications were reported in 12.26% of horses that received IV (n = 155) and 33% of horses that received intraosseous (27) A-RLP. Horses with septic synovitis had a lower survival rate (53.43%) than did horses with lacerations (91.89%). Within group 2, no significant differences in short- or long-term outcomes were found between horses with extrasynovial and fresh, minimally contaminated intrasynovial lacerations. For the horses returning to previous use, 80% of horses with septic synovitis and 72.72% of horses with lacerations were performing at the same or higher level at the time of follow-up. CONCLUSIONS AND CLINICAL RELEVANCE The results of the present study indicated that A-RLP is a safe technique with minimal adverse effects. The IV route presented fewer complications than intraosseous injection. Horses with infection of synovial structures had a lower survival rate than did those with acute, minimally contaminated intrasynovial lacerations. The latter had a similar prognosis for horses with extrasynovial lacerations treated with A-RLP.

Clinical and pharmacokinetic effects of regional or general anaesthesia on intravenous regional limb perfusion with amikacin in horses

REASONS FOR PERFORMING STUDY Antimicrobial i.v. regional limb perfusion (IV-RLP) is clinically performed on anaesthetised or sedated horses with or without regional anaesthesia. To date, no scientific data are available on the clinical and pharmacokinetic effects of these anaesthetic protocols on antimicrobial IV-RLP, which is believed to result in better tourniquet efficiency due to decreased movement. OBJECTIVE To determine the effects of regional or general anaesthesia on the clinical and synovial pharmacokinetic parameters of amikacin administered by IV-RLP to horses. STUDY DESIGN Experimental crossover study. METHODS Eight healthy horses received 4 treatments of amikacin IV-RLP in a randomised, blinded, crossover design: standing sedation without regional anaesthesia (CNT); standing sedation with i.v. regional anaesthesia; standing sedation with perineural regional anaesthesia (PNA); or general anaesthesia. Synovial fluid amikacin concentrations were measured over 24 h and regional pharmacokinetic parameters calculated. Heart and respiratory rates, visual analogue scale of discomfort, number of times the limb was lifted and number of additional sedations administered were recorded. Analysis of variance crossover analysis was applied with significance level at P < 0.05. RESULTS Amikacin concentrations and regional pharmacokinetic parameters did not differ significantly among treatments. Visual analogue scores (mean ± s.d.) were significantly lower with PNA (19 ± 15) vs. i.v. regional anaesthesia (69 ± 36) or CNT (81 ± 13; P < 0.001). Significantly less lifting of the limb (mean ± s.d.) occurred with PNA (20 ± 20) vs. CNT (54 ± 22; P < 0.04). CONCLUSIONS Perineural regional anaesthesia before IV-RLP was most effective in providing comfort to standing, sedated horses without significantly affecting the regional pharmacokinetic parameters of amikacin. High variability of synovial amikacin concentrations was present. The use of general anaesthesia for IV-RLP is not justified based on this study.

Mechanical properties of subchondral bone in the distal aspect of third metacarpal bones from Thoroughbred racehorses

OBJECTIVE To characterize the mechanical properties of subchondral bone (SCB) of the distopalmar aspect of the condyles of the third metacarpal bone (MC3) and their correlations with structural aspects of MC3s in Thoroughbred racehorses. SAMPLE POPULATION 12 pairs of MC3s from Thoroughbred racehorses euthanized for various reasons. PROCEDURES MC3s were collected from horses with mild (n = 6) and with severe (6) SCB changes, as determined by micro-computed tomography (CT). Specimens of SCB plate and trabecular bone were cut from the distopalmar aspect of condyles and sagittal ridge and examined with 3-dimensional micro-CT. Specimens were tested in compression, and elastic modulus, yield stress, yield strain, and toughness were calculated. Apparent and true bone mineral density, bone volume fraction, trabecular thickness, trabecular separation, and connectivity were also calculated. Differences in mechanical properties among various classifications of bone were evaluated. Correlations between structural and mechanical variables were also assessed. RESULTS No differences were detected between left and right forelimbs. Specimens from condyles had higher values for elastic modulus, yield stress, and toughness than did specimens of sagittal ridge. In SCB with severe changes attributable to SCB disease, SCB plate was weaker and trabecular bone was stronger than in SCB with mild changes. Microstructural and mechanical properties were significantly correlated. CONCLUSIONS AND CLINICAL RELEVANCE A marked gradient in mechanical properties of SCB from horses, which could be involved in the pathogenesis of condylar fractures, was detected. Mechanical properties of SCB from the distal aspect of MC3s can be predicted to some extent via micro-CT.

Structural characterization of subchondral bone in the distal aspect of third metacarpal bones from Thoroughbred racehorses via micro–computed tomography

OBJECTIVE To characterize the microstructure of subchondral bone (SCB) plate and trabecular bone (TBB) of the distopalmar aspect of the condyles of third metacarpal bones (MC3s) from Thoroughbred racehorses at 2 different stages of SCB disease via micro-computed tomography (CT). SAMPLE POPULATION 12 pairs of MC3s from Thoroughbred racehorses euthanized for various reasons. PROCEDURES MC3s were collected from horses with mild (n = 6) or severe (6) SCB disease, as determined via micro-CT. Cubic (6 x 6 x 6-cm) specimens of SCB plate and TBB were cut from the palmar aspect of condyles and sagittal ridges and examined with 3-dimensional micro-CT. For each specimen, apparent bone mineral density (aBMD), true BMD (tBMD), bone volume fraction (BVF), trabecular thickness (TBT), trabecular separation (TBS), and connectivity (CN) were calculated. RESULTS Condyles had higher aBMD, tBMD, BVF, and TBT and lower TBS than did the sagittal ridge. In bone specimens with mild SCB changes, SCB plate had higher aBMD, TBT, and CN and lower TBS than did TBB. In bone specimens with severe SCB disease, TBB had higher aBMD and TMD and lower TBS than it did in bone specimens with mild disease, and values were similar to those for SCB plate in bone specimens with severe disease. CONCLUSIONS AND CLINICAL RELEVANCE The microstructure of SCB of the distopalmar aspect of metacarpal condyles of horses varied according to the severity of changes identified via micro-CT. With mild SCB disease, sclerosis existed in the SCB plate of the condyles; with severe disease, sclerosis also invaded condylar TBB.

Effect of repeated through-and-through joint lavage on serum amyloid A in synovial fluid from healthy horses

The objective of this study was to evaluate the effect of through-and-through joint lavage on systemic and synovial serum amyloid A (SAA), total protein, nucleated cell count and percentage of neutrophils in the synovial fluid of six healthy horses. A prospective experimental study was performed where one healthy tarsocrural joint of each horse was randomly assigned to receive repeated through-and-through joint lavage at 0, 48 and 96 h. Synovial fluid and blood samples were collected at 0 (baseline), 24, 48, 72, 96 and 120 h. Systemic and synovial SAA, total protein, nucleated cell count and percentage of neutrophils were measured and compared to baseline. Concentrations of systemic and synovial SAA percentage of neutrophils were not increased from baseline in contrast to total protein and nucleated cell counts (except for nucleated cell count at 96 h). In conclusion, repeated through-and-through joint lavage did not affect synovial SAA concentrations in horses; however, synovial total protein and nucleated cell count values increased. Some of the total protein and nucleated cell count values observed in this study were within the range reported for septic arthritis 24 h after joint lavage. Hence, synovial SAA may be a valuable marker to evaluate the clinical progression of septic joints after through-and-through joint lavage. Clinical studies evaluating synovial fluid SAA concentrations while treating synovial sepsis with through-and-through joint lavage are warranted.

Effect of Arthroscopic Lavage on Systemic and Synovial Fluid Serum Amyloid A in Healthy Horses

OBJECTIVE To evaluate the effect of arthroscopic lavage on systemic serum amyloid A (SAA) and SAA, total protein, nucleated cell count, and percentage of neutrophils in synovial fluid in healthy horses. STUDY DESIGN Prospective experimental study. ANIMALS Healthy adult horses (n = 6). METHODS Middle carpal joints were randomly assigned to 1 of 2 treatments: arthrocentesis (controls) or arthroscopic lavage, with 30 day washout period between treatments. Synovial fluid and blood samples were collected at 0, 24, 48, 72, 96, and 120 hours. Measurements included systemic and synovial fluid SAA, as well as total protein, nucleated cell count, and percentages of neutrophils in synovial fluid. Data were analyzed by median quantile regression and Wilcoxon signed-rank test and significance level set at P < .05. RESULTS Systemic and synovial fluid SAA did not increase from baseline (except systemic SAA at 24 hours for both treatments) and were not significantly different between treatments. Total protein values were significantly increased after arthroscopic lavage (except at 96 hours) but not in controls at all time points. With both treatments, nucleated cell counts significantly increased from baseline values at all time points. Percentages of neutrophils were significantly increased after arthroscopic lavage at all time points, but only at 24 hours in controls. CONCLUSION Total protein, nucleated cell count, and percentage of neutrophils in synovial fluid were significantly increased after arthroscopic lavage; however, synovial fluid SAA was not affected by this procedure. Further research is warranted to validate synovial fluid SAA as a monitoring tool during treatment of septic arthritis.

Prevalence and antimicrobial susceptibility of bacterial isolates from horses with synovial sepsis: A cross-sectional study of 95 cases.

Bacterial culture and antimicrobial susceptibility testing of septic synovial samples allows instigation of targeted antimicrobial therapy; however, bacterial culture takes more than 24 h and has low sensitivity. This study aimed to identify the most frequently cultured bacteria and their antimicrobial susceptibility profile from septic synovial samples in our referral equine hospital, to allow recommendations regarding appropriate initial antimicrobial therapy prior to culture results. Hospital records for all horses with synovial sepsis and a synovial sample submitted to the microbiology laboratory between 2004 and 2013 were retrieved (n= 379 samples). One horse had positive cultures from more than one synovial structure, and two horses had positive cultures obtained from repeat samples. Overall, 114 bacterial isolates were obtained. Gram-positive bacteria were isolated in 75% of cases, of which 22% were haemolytic Staphylococcus spp., and 52% were Staphylococcus aureus including two multidrug-resistant isolates. Gram-negative bacteria were isolated from 25% of cases. Anaerobic Clostridium spp. was isolated in 3% of cases. Of the first line antimicrobials, oxytetracycline and doxycycline were effective against 70-100% of the Gram-positive bacteria and 20-100% of the Gram-negative organisms, whilst trimethoprim-sulphamethoxazole and gentamicin efficacy ranged between 50% and 88% for both Gram-positive and Gram-negative bacteria. Of the equine protected antimicrobials, ceftiofur was effective against 70-90% of all bacterial isolates whilst 80% of isolates were susceptible to enrofloxacin. These results indicate that tetracyclines, trimethoprim-sulphamethoxazole or gentamicin may be suitable first-line antimicrobials for treatment of synovial sepsis cases while awaiting laboratory results, findings which support current recommendations for antimicrobial stewardship in equine medicine.

Laparoscopic Vasectomy in African Elephants (Loxodonta africana)

OBJECTIVE To describe a surgical technique for, and outcome after, laparoscopic vasectomy of free-ranging elephants. STUDY DESIGN Case series. ANIMALS African elephants (Loxodonta africana; n = 14). METHODS Male elephants (12-35 years old) were anesthetized with etorphine and supported in a sling in a modified standing position, and positive pressure ventilated with oxygen. Anesthesia was maintained with IV etorphine. Vasectomy was performed under field conditions by bilateral, open-approach, flank laparoscopy with the abdomen insufflated with filtered ambient air. A 4-cm segment of each ductus deferens was excised. Behavior and incision healing were recorded for 8 months postoperatively. RESULTS Successful bilateral vasectomy (surgical time, 57-125 minutes) was confirmed by histologic examination of excised tissue. Recovery was uneventful without signs of abnormal behavior. Large intestine lacerations (3 elephants; 1 full and 2 partial thickness) were sutured extracorporeally. One elephant found dead at 6 weeks, had no prior abnormal signs. Skin incisions healed without complication. CONCLUSIONS Laparoscopic vasectomy can be performed in African elephants in their natural environment.

Analysis of the subchondral microarchitecture of the distopalmar aspect of the third metacarpal bone in racing Thoroughbreds

OBJECTIVE To determine the anisotropic characteristics of the microarchitecture of the subchondral bone (SCB) plate and trabecular bone (TBB) of the distopalmar aspect of the metacarpal condyles in horses with different stages of SCB disease. SAMPLE POPULATION 12 third metacarpal bone pairs from racing Thoroughbreds euthanized for diverse reasons. PROCEDURES Both metacarpi were collected from horses with SCB changes that were mild (sclerosis and focal radiolucencies; n=6) or severe (multifocal radiolucencies and articular surface defects; 6). Sample blocks of SCB plate and TBB were collected from the distopalmar aspect of both condyles and the sagittal ridge and examined via 3-D micro-computed tomography at 45-?m isotropic voxel resolution. For each sample, the angle between the principal orientation of trabeculae and the sagittal plane and the degree of anisotropy (DA) were calculated from mean intercept length measurements. RESULTS Condylar samples had significantly lower angle (mean, 8.9°; range, 73° to 10.9°) than sagittal ridge samples (mean, 40.7°; range, 33.6° to 49.2°), TBB had significantly higher DA (mean±SE, 1.75±0.04) than SCB plate (1.29±0.04), and mildly diseased TBB had higher DA (1.85±0.06) than severely diseased TBB (1.65±0.06). CONCLUSIONS AND CLINICAL RELEVANCE The highly ordered appearance of trabeculae within the condyles supports the concept that joint loading is primarily transmitted through the condyles and not the sagittal ridge. The sharp changes in the trajectories of the SCB trabeculae at the condylar grooves may be indicative of hypothetical tensile forces at this location contributing to the pathogenesis of condylar fractures.

Elbow joint luxation in a 1‐month‐old foal

This paper reports on luxation of the elbow joint without concomitant fracture in a 1-month-old foal. Conservative treatment, with closed reduction and full-limb bandaging, including caudal and lateral splints, seemed successful initially, however, failed to provide enough stability and luxation recurred, and open reduction and surgical placement of prosthetic collateral ligaments was required. Luxation of the elbow joint should be considered when acute non-weight bearing forelimb lameness occurs associated with pain and swelling in the area of the elbow in young foals. Closed reduction failed to provide sufficient joint stability.