In vitro efficacy of a 0.2% polyhexamethylene biguanide-impregnated gauze dressing against pathogenic bacterial isolates found in horses.

OBJECTIVE: To determine the ability of 0.2% polyhexamethylene biguanide (PHMB)-impregnated gauze to inhibit the growth of bacteria isolated from equine infected sites. STUDY DESIGN: In vitro study. METHODS: Nine bacterial isolates were obtained from cultures submitted from equine patients presenting with penetrating injuries of the hoof (n = 4), septic osteitis (n = 1), synovial sepsis (n = 1), wounds (n = 2), and incisional infection following laparotomy (n = 1). Two standardized strains were also included. A standard inoculum of each isolate was placed on 12 Muller-Hinton agar plates. Squares (2.5 cm × 2.5 cm) of 0.2% PHMB-impregnated (n = 6) and nonimpregnated control gauze (n = 6) were placed on inoculated agar plates. Bacterial growth under each gauze square was assessed after a 24-h incubation period and areas of inhibition were measured to a standardized scale, using image-processing software. Mean ± SD growth inhibition (%) using 0.2% PHMB-impregnated gauze was compared to the nonimpregnated gauze for each isolate using Student's t test (p < .05). RESULTS: The 0.2% PMHB-impregnated gauze inhibited the growth of Staphylococcus spp. (n = 4) by 33%-83.1% and that of Escherichia coli spp. (n = 4) by 6.5%-37%. There was no inhibition of growth of Pseudomonas aeruginosa or either Enterococcus spp. CONCLUSION: The 0.2% PHMB-impregnated dressing tested here inhibited the growth of staphylococcal and E. coli isolates, but the magnitude of inhibition varied between strains. CLINICAL RELEVANCE: These results justify in vivo studies to evaluate the ability of the dressing to reduce the bacterial growth of common equine bacterial pathogens in clinical practice.

Orthopedic Infections-Clinical Applications of Intravenous Regional Limb Perfusion in the Field.

For the equine veterinarian, orthopedic emergencies are a common occurrence in clinical practice, with traumatic wounds of the distal limb and penetrating injuries of the hoof being some of the most common medical conditions to affect horses. Intravenous regional limb perfusion is a technique widely used for the treatment of orthopedic infections in horses. The objectives of this review are to discuss some of the clinical applications for this treatment modality in the field and to review the technique for the practitioner.

Incidence of incisional complications after exploratory celiotomy in equids affected with enterolithiasis.

This study reports the prevalence of and risk factors for incisional complications in equids after ventral midline celiotomy for enterolithiasis. This study covered the years 2008 to 2015 and included 72 equids. Enteroliths were removed from the ascending or descending colon through 1 or more enterotomies. Complications were defined as surgical site infection and/or incisional hernia formation. Follow-up by telephone questionnaire or medical records determined that 10/72 (13.9%) equids experienced complications, with 6/72 (8.3%) developing a surgical site infection and 5/72 (6.9%) a hernia. Seven of ten were presented for chronic abdominal discomfort (> 24 hours), and 8/10 had right dorsal colon and pelvic flexure enterotomies. All equids that developed an incisional hernia and 4 with surgical site infection had enteroliths > 15 cm diameter removed from the right dorsal colon. Antimicrobial powder applied to the ventral midline incision during closure significantly reduced incisional complications. Removal of > 15 cm diameter enteroliths from the right dorsal colon may predispose to postoperative incisional complications.

Incidence des complications incisionnelles après une céliotomie exploratoire chez des équidés atteints d'entérolithiase. Cette étude rapporte la prévalence et les facteurs de risque des complications incisionnelles chez les équidés opérés pour l'entérolithiase en utilisant une celiotomie médiane ventrale de 2008 à 2015. Soixantedouze équidés ont été inclus. Les entérolithes ont été retirés du côlon ascendant ou descendant par ≥ 1 entérotomies. Les complications étaient définies comme une infection du site opératoire et/ou la formation d'une hernie incisionnelle. Le suivi a été obtenu par questionnaire téléphonique ou par dossiers médicaux. Dix des 72 (13,9 %) des équidés ont eu des complications, dont 6/72 (8,3 %) ont développé une infection du site opératoire et 5/72 (6,9 %) une hernie. Sept sur 10 ont été présentés pour un malaise abdominal chronique (> 24 heures) et 8/10 avaient des entérotomies du côlon dorsal droit et de la flexion pelvienne. Tous les équidés ayant développé une hernie incisionnelle et quatre avec une infection du site opératoire avaient des entérolithes > 15 cm de diamètre prélevés du côlon dorsal droit. La poudre antimicrobienne appliquée sur l'incision médiane ventrale lors de la fermeture réduisait significativement les complications incisionnelles. Le retrait d'entolithes de > 15 cm de diamètre du côlon dorsal droit peut prédisposer aux complications incisionnelles postopératoires.(Traduit par les auteurs).

Predictive value of plasma and peritoneal creatine kinase in horses with strangulating intestinal lesions.

OBJECTIVE: To determine the ability of plasma and peritoneal creatine kinase (CK) to predict the presence of a strangulating lesion in horses presented for colic. STUDY DESIGN: Prospective clinical study. ANIMALS: Ten healthy control horses and 61 clinical colic cases. METHODS: Creatine kinase activity was measured in peritoneal fluid and plasma of 10 healthy horses and 61 horses presenting for colic (40 horses with nonstrangulating lesions and 21 horses with strangulating lesions). Information on other blood and peritoneal fluid variables, signalment, results from the physical examination, outcome, requirement for surgery, and lesion location and type were retrieved from the medical records of horses presenting for colic. RESULTS: A peritoneal CK cutoff level of 16 IU/L yielded a sensitivity of 95.2% and a specificity of 84.6% (positive predictive value [PPV] = 76.9% and negative predictive value [NPV] = 97%, respectively) for predicting a strangulating lesion. A peritoneal lactate cutoff level of 3.75 mmol/L yielded a sensitivity of 81% and a specificity of 92% (PPV = 85% and NPV = 90%, respectively) for predicting a strangulating lesion. CONCLUSION: Peritoneal CK concentration was a sensitive indicator of the presence of a strangulating lesion in horses presenting with colic, whereas peritoneal lactate concentration was a more specific indicator. CLINICAL SIGNIFICANCE: Measuring CK in peritoneal fluid may be a useful adjunct to clinical case presentation to accelerate the diagnosis and definitive treatment of horses presenting with strangulating intestinal lesions, thereby improving their outcome.

Catastrophic gastric rupture in a horse secondary to psyllium pharmacobezoars.

A mare was euthanized because of gastric rupture secondary to complete duodenal obstruction by 2 bezoars located in the pylorus and proximal duodenum. Infrared spectroscopy showed that the bezoars were composed of psyllium. The mare had been receiving treatment with a pelleted psyllium product at 4 times the recommended dosage. Veterinarians should be aware that treatment of colic in horses with pelleted psyllium products could be associated with gastric impaction.

Rupture gastrique catastrophique secondaire à des pharmacobézoards de psyllium en boulettes chez un cheval. Une jument a été euthanasiée en raison d'une rupture gastrique secondaire à une obstruction duodénale complète par deux bézoards situés dans le pylore et le duodénum proximal. La spectroscopie infrarouge a montré que les bézoards se composaient de psyllium. La jument avait reçu un traitement composé d'un produit de psyllium en boulettes à quatre fois la dose recommandée. Les vétérinaires devraient être au courant que le traitement des coliques chez les chevaux avec des produits de psyllium en boulettes pourrait être associé à une impaction gastrique.(Traduit par Isabelle Vallières).

Clinical findings and management of 153 horses with large colon sand accumulations.

OBJECTIVE: To determine the influence of radiographic quantification of sand accumulation on the medical versus surgical management of large colon sand accumulations. To compare short- and long-term outcomes and complications associated with medical and surgical management of these horses. STUDY DESIGN: Retrospective. SAMPLE POPULATION: A total of 153 horses. METHODS: Medical records and abdominal radiographs of horses presented for colic between 2004 and 2014 were reviewed. Severity of sand accumulation was quantified by tracing and measuring a region of interest with a commercial software program. Breed, weight, amount of sand, presence of diarrhea at presentation, treatment, and the development of complications were recorded. RESULTS: Records from 153 horses were reviewed. The mean cross-sectional area of sand accumulation was 692.9 cm2 (median = 658.7 cm2 , 84.6-1780.7 cm2 ). Increased accumulation of gas on radiographs and abnormal transrectal examination findings were associated with an increased likelihood of surgery. The most common complication was the development of diarrhea (20.3%) with only 4 (2.6%) horses positive for Salmonella spp. Horses had a favorable prognosis, with 94.8% of horses treated medically and 94.7% of those treated surgically surviving to discharge. CONCLUSION: Increased accumulation of gas on radiographs and transrectal palpation of impaction or intestinal gas distension increase the likelihood of surgery. Both medical and surgical treatments carry a good prognosis. CLINICAL RELEVANCE: The sheer quantity of sand is not a factor when determining surgical intervention. Attention should be paid to the presence of increased gas accumulation on rectal or radiographic examination.

A novel ultrasonographic assisted technique for desmotomy of the palmar/plantar annular ligament in horses.

OBJECTIVES: To describe an ultrasound assisted technique for desmotomy of the palmar/plantar annular ligament (PAL), determine its efficacy and intraoperative complications. STUDY DESIGN: Cadaveric and in vivo study. ANIMALS: Cadaveric limbs (n = 12), adult horses (n = 4), and clinical cases (n = 2). METHODS: Ultrasound assisted desmotomy of the palmar/plantar annular ligament (UAD-PAL) was performed in cadaveric limbs and in standing horses with the operated limb placed in a distal limb splint. The procedure was performed under general anesthesia and was followed by tenoscopic examination in 2 clinical cases. A hook knife was developed for the procedure. Complete transection was assessed by postmortem dissection (10 forelimbs, 10 hindlimbs) and tenoscopic examination (1 forelimb, 1 hindlimb). Thickness of PAL, surgery time, other intraoperative parameters and complications associated with the procedure were recorded. RESULTS: Complete PAL transection was accomplished in 20/22 limbs. No iatrogenic damage to adjacent intrathecal structures was identified in any case. The instrument was correctly positioned on the first attempt in 19/22 cases. The most common intraoperative complication was inadvertent subcutaneous placement of the instrument (n = 2). Significant thickening of the PAL (3 mm) was present in 1/2 limbs in which complete transection was not achieved. CONCLUSIONS: UAD-PAL with the custom-made hook knife was effective at transecting the PAL with minimal intraoperative complications. The procedure can be performed in standing sedated horses. Another method should be considered in horses with thickened PAL.

Use of an Absorbable Urethral Stent for the Management of a Urethral Stricture in a Stallion.

OBJECTIVE: To describe the successful management of a urethral stricture with an absorbable stent in a stallion. STUDY DESIGN: Clinical report. ANIMALS: Stallion with a urethral stricture. RESULTS: A 12-year-old Thoroughbred breeding stallion was evaluated for acute onset of colic. Uroperitoneum because of presumptive urinary bladder rupture, with urethral obstruction by a urethrolith, was diagnosed. The uroperitoneum was treated conservatively. The urethrolith was removed through a perineal urethrotomy. Approximately 15 weeks after urethrolith removal, the stallion presented with a urethral stricture. The stricture was unsuccessfully treated with an indwelling urinary catheter and 4 attempts at balloon dilation. Eight weeks after diagnosis of stricture, an absorbable polydioxanone (20 mm × 80 mm) urethral stent was implanted under percutaneous, ultrasound guidance. Urethroscopy was performed at 70, 155, and 230 days after stent placement and the endoscope passed through the affected site without complication. Urethroscopy at 155 days showed the stent had been reabsorbed. Follow-up 20 months after stent placement reports the stallion was able to void a normal urine stream. CONCLUSIONS: Absorbable urethral stent placement was a feasible treatment for urethral stricture in this stallion.

Sialoendoscopy as a treatment for an obstructed mandibular salivary duct in a horse.

A 14-year-old Quarter Horse was examined for a draining tract of 8 months' duration on the right mandible that was non-responsive to antibiotic therapy and surgical therapy. Further investigation and subsequent treatment with sialoendoscopy and ultrasonography were performed to relieve an obstruction of plant awns in the mandibular salivary duct.

Sialo-endoscopie comme traitement pour un canal salivaire mandibulaire bloqué chez un cheval. Un cheval Quarter Horse âgé de 14 ans a été examiné pour une fistule purulente d'une durée de 8 mois à la mandibule droite qui ne répondait pas à la thérapie antibiotique et à la thérapie chirurgicale. De nouvelles investigations et le traitement subséquent à l'aide de la sialo-endoscopie et de l'échographie ont été réalisés pour éliminer un blocage du canal salivaire mandibulaire par des barbes de plantes.(Traduit par Isabelle Vallières).

Evaluation of 3 handheld portable analyzers for measurement of L-lactate concentrations in blood and peritoneal fluid of horses with colic.

OBJECTIVE: To compare 3 portable handheld analyzers with a bench top blood gas analyzer for measurement of blood and peritoneal fluid L-lactate concentrations in horses admitted with signs of colic. STUDY DESIGN: Prospective clinical study. SAMPLE POPULATION: Blood and peritoneal fluid from horses with colic. METHODS: L-lactate concentrations in heparinized blood and peritoneal fluid were measured serially on 10 occasions to evaluate repeatability of the portable analyzers. Blood and peritoneal fluid L-lactate concentrations were simultaneously evaluated by a bench top and 3 portable analyzers and the results compared by intraclass correlation coefficients and Bland Altman plots. L-Lactate concentrations in a subgroup of peritoneal fluid samples were evaluated by a chromogenic laboratory assay and compared with the bench top and the handheld analyzers. RESULTS: Portable lactate analyzers had good intra-analyzer reliability for peritoneal fluid. Two portable analyzers had poor intra-analyzer reliability for mid concentrations of L-lactate in blood. L-lactate measurements from portable analyzers were closer to the bench top analyzer at low concentrations of L-lactate than at higher concentrations. Compared with the bench top analyzer, the Lactate Pro and Lactate Plus have the highest intraclass correlation coefficient and the smallest bias for peritoneal fluid and blood L-lactate, respectively. The bench top analyzer and the Lactate Pro had the highest level of agreement for peritoneal fluid compared with the chromogenic assay. CONCLUSIONS: Although portable analyzers are alternatives for the measurement of L-lactate concentration in field situations, clinicians need to be aware of the variable results between analyzers, especially when extrapolating means or cutoff values from studies using different lactate analyzers.

Identification, management and outcome of postoperative hemoperitoneum in 23 horses after emergency exploratory celiotomy for gastrointestinal disease.

OBJECTIVE: To investigate postoperative hemoperitoneum in a population of horses that had surgery for colic. STUDY DESIGN: Retrospective case series. ANIMALS: Horses (n = 23). METHODS: Preoperative, intraoperative, and postoperative information was obtained from medical records (1985-2012) of horses with postoperative hemoperitoneum after emergency exploratory celiotomy. Pre-existing hemoperitoneum during surgery and nonsurgical hemoperitoneum were excluded. RESULTS: Of 4520 horses that had emergency exploratory celiotomy for gastrointestinal disease, 23 horses met inclusion criteria; an incidence of 0.5%. Horse signalment approximated the colic population, although Thoroughbreds were significantly overrepresented. Hemoperitoneum was significantly associated with intestinal resection. Postoperative hemoperitoneum was recognized a mean (± SD) of 1.0 ± 0.7 days after surgery and associated with tachycardia, decreasing hematocrit, incisional drainage, or ultrasonographic identification of swirling, echogenic abdominal fluid. Primary treatments included intravenous fluid therapy (n = 23), colloid support (20), blood transfusion (13), and antifibrinolytic agents (11). Fifteen horses (65%) survived to discharge, which was associated with admission lactate and days of hospitalization. CONCLUSIONS: Postoperative hemoperitoneum is a rare complication of exploratory celiotomy in horses that should be considered when there are signs of abdominal discomfort and declining hematocrit in the early postoperative period. Prognosis is guarded because of potential sequelae of septic peritonitis and adhesion formation.

Evaluation of the effect of onlay mesenteric flaps on end-to-end jejunojejunostomy healing in horses.

OBJECTIVE: To evaluate the effect of onlay mesenteric flaps (MFs) with end-to-end jejunojejunostomy on stomal diameter, length of jejunum with reduced stomal diameter, abdominal adhesion formation, and healing. STUDY DESIGN: Experimental study. ANIMALS: Healthy adult horses (n = 6). METHODS: Two hand sewn end-to-end jejunal anastomoses using a 1 layer simple continuous serosubmucosal suture pattern were performed in each horse ∼ 2 and 5 m oral to the ileocecal fold. Using a random design for selection anastomosis location (oral or aboral), 1 anastomosis was covered with 2 adjacent onlay MFs secured with interrupted sutures and cyanoacrylate glue. Two weeks later, adhesion formation, stomal diameter, length of reduced jejunal stomal diameter, and healing were evaluated. RESULTS: Use of onlay MFs decreased stomal diameter (P = .05), increased length of reduced peristomal jejunal diameter (P = .05), surgical time (P = .003), and serosal fibrosis (P = .05). No difference was evident for adhesion formation, and degree of inflammation between techniques. CONCLUSION: End-to-end jejunojejunostomy covered with 2 onlay MFs is not recommended because this technique results in luminal reduction.

Sinusitis associated with nasogastric intubation in 3 horses.

Sinusitis has not been reported as a complication of long-term nasogastric intubation in horses. We describe 3 horses that developed nosocomial sinusitis following abdominal surgery with associated perioperative nasogastric intubation. Sinusitis was suspected by the presence of malodorous discharge and confirmed by percussion, upper airway endoscopy, radiographs (n = 3), and bacterial culture (n = 1).

Sinusite associée à l'intubation naso-gastrique chez 3 chevaux. La sinusite n'a a pas été signalée comme une complication de l'intubation naso-gastrique à long terme chez les chevaux. Nous décrivons 3 chevaux qui ont développé une sinusite nosocomiale après une chirurgie abdominale utilisant une intubation naso-gastrique péri-opératoire connexe. La sinusite a été suspectée en observant la présence d'un écoulement malodorant et confirmée par percussion, endoscopie des voies respiratoires supérieures, radiographies (n = 3) et culture bactérienne (n = 1).(Traduit par Isabelle Vallières).

Increasing tourniquet number has no effect on amikacin concentration within the radiocarpal joint in horses undergoing intravenous regional limb perfusion.

OBJECTIVE: To determine whether IV regional limb perfusion (IVRLP) performed in the cephalic vein with a wide rubber tourniquet (WRT) applied proximal and distal to the carpus results in a higher peak concentration (Cmax) of amikacin in the radiocarpal joint (RCJ), compared with the Cmax for IVRLP using a single WRT proximal to the carpus. ANIMALS: 7 healthy adult horses. PROCEDURES: Horses underwent IVRLP using standing sedation with 2 g of amikacin sulfate diluted to 60 mL by use of saline (0.9% NaCl) solution in the cephalic vein with 2 different tourniquet techniques; proximal WRT (P) and proximal and distal WRT (PD). Synovial fluid was collected from the RCJ at 5, 10, 15, 20, 25, and 30 minutes after IVRLP. Tourniquets were removed after the 30-minute sample was collected. Blood samples from the jugular vein were collected at 5, 10, 15, 20, 25, 29, and 31 minutes after IVRLP. Amikacin concentration was quantified by a fluorescence polarization immunoassay. Median peak concentration (Cmax) of amikacin and time to maximum drug concentration (Tmax) within the RCJ were determined. RESULTS: Median peak concentration in the RCJ was 1331.4 µg/mL with technique P and 683.1 µg/mL with technique PD. Median Tmax occurred at 30 minutes with technique P and 25 minutes with technique PD. No significant (Cmax, P = 0.18; Tmax, P = 0.6) difference in amikacin Cmax or Tmax between techniques was detected. CLINICAL RELEVANCE: Placement of 2 WRTs offers no advantage to a single proximal WRT when performing IVRLP to deliver maximal amikacin concentrations to the RCJ using IVRLP.

Comparison of pH, lactate, and glucose analysis of equine synovial fluid using a portable clinical analyzer with a bench-top blood gas analyzer.

OBJECTIVE: To compare agreement between a portable clinical analyzer and laboratory-based bench-top analyzer for analysis of pH, lactate, and glucose concentrations in synovial fluid. STUDY DESIGN: Prospective experimental study. ANIMALS: Clinically normal horses (n=8); 6 horses euthanatized for reasons unrelated to the study; 11 horses that had synoviocentesis for reasons other than sepsis; 7 horses that had synoviocentesis for evaluation of sepsis; and 2 horses without recorded clinical data. Median age of horses was 8 years (range, 1 day to 24 years). METHODS: Supernatant from each synovial fluid sample was analyzed for pH, lactate, and glucose concentrations using an ABL 705 laboratory-based bench-top analyzer and i-STAT portable clinical analyzer. Bland-Altman plots were constructed and concordance analysis performed to determine bias and agreement between the 2 analyzers. RESULTS: There was acceptable agreement between analyzers for lactate and glucose concentrations, with biases of 0.198 mmol/L and 9 mg/dL and concordance correlation coefficients of 0.97 and 0.96 for lactate and glucose, respectively. The agreement between analyzers for pH was not acceptable, with a bias of -0.057 and concordance correlation coefficient of 0.89. CONCLUSIONS: This study found that the portable clinical analyzer performed similarly to the bench-top blood gas analyzer for evaluation of lactate and glucose concentrations, but not pH, in synovial fluid.

Effects of aerobic and anaerobic fluid collection on biochemical analysis of peritoneal fluid in healthy horses and horses with colic.

OBJECTIVE: To determine whether in healthy horses and those with colic, exposure of peritoneal fluid to room air affects values obtained on biochemical analysis. STUDY DESIGN: Prospective study. ANIMALS: Adult horses with a primary complaint of acute abdominal pain (n=29) and 12 healthy horses. METHODS: Peritoneal fluid was aseptically collected under aerobic and anaerobic conditions. After collection, pH, PCO(2) , PO(2) , HCO(3) (-) , Na(+) , ionized Ca(2+) , K(+) , lactate, and glucose were immediately measured using a commercial blood gas analyzer. Biochemical variables were compared between aerobically and anaerobically obtained samples using a paired t-test. RESULTS: In healthy horses, peritoneal fluid samples collected under anaerobic conditions had higher PCO(2) and ionized Ca(2+) and lower PO(2) , HCO(3) (-) , and pH compared with samples exposed to air. No differences were observed for K(+) , Na(+) , glucose, and lactate. In horses with colic, samples collected anaerobically had higher PCO(2) , ionized Ca(2+) , Na(+) , and glucose and lower PO(2) , HCO(3) (-) , and pH value compared with samples exposed to air. No differences were observed for K(+) and lactate. CONCLUSION: Exposure of peritoneal fluid to room air had a significant effect on pH, PCO(2) , PO(2) , and variables associated or dependent on changes in pH such as HCO(3) (-) and ionized Ca(2+) . Interpretation of biochemical analysis of peritoneal fluid may be influenced by sample collection method.

Peritoneal and plasma D-lactate concentrations in horses with colic.

OBJECTIVE: To evaluate the association between peritoneal fluid and plasma d-lactate concentration with variables used in the diagnosis and prognosis of horses with colic. ANIMALS: Clinically healthy horses (n=6) and 90 horses with colic. STUDY DESIGN: Prospective cross-sectional study. METHODS: D-lactate concentration was determined in peritoneal fluid and plasma of all horses. Information on other blood and peritoneal fluid variables, signalment, results from the physical examination, outcome, need for surgery, lesion location, and type was retrieved from medical records. RESULTS: Peritoneal D-lactate concentration was strongly correlated with plasma D-lactate concentration (r=0.71; P<.001). Peritoneal and plasma D-lactate concentrations were positively correlated with peritoneal (r=0.8; P<.001) and plasma L-lactate (r=0.33; P=.001) concentrations, respectively. Peritoneal D-lactate concentration was negatively correlated with survival to discharge (U=430.5; P<.001). Median peritoneal D-lactate concentration of horses with septic peritonitis (455.2 µmol/L) and horses with gastrointestinal rupture (599.5 µmol/L) were higher compared with horses with nonstrangulating obstructions (77.7 µmol/L). A cut-off concentration of peritoneal D-lactate of 116.6 µmol/L had a sensitivity of 0.813 and a specificity of 0.651 to differentiate between nonstrangulating and strangulating obstructions. CONCLUSIONS: Peritoneal D-lactate concentration may be more useful for identifying horses with strangulating obstructions (high sensitivity, low probability of a false negative) than to ruling out strangulating obstruction (moderate specificity, high probability of a false positive).

Time required to achieve maximum amikacin concentration in the synovial fluid of the tarsocrural joint following administration of the drug by intravenous regional limb perfusion in horses.

OBJECTIVE: To determine the median time to maximum concentration (tmax) of amikacin in the synovial fluid of the tarsocrural joint following IV regional limb perfusion (IVRLP) of the drug in a saphenous vein of horses. ANIMALS: 7 healthy adult horses. PROCEDURES: With each horse sedated and restrained in a standing position, a 10-cm-wide Esmarch tourniquet was applied to a randomly selected hind limb 10 cm proximal to the point of the tarsus. Amikacin sulfate (2 g diluted with saline [0.9% NaCl] solution to a volume of 60 mL) was instilled in the saphenous vein over 3 minutes with a peristaltic pump. Tarsocrural synovial fluid samples were collected at 5, 10, 15, 20, 25, and 30 minutes after completion of IVRLP. The tourniquet was removed after collection of the last sample. Amikacin concentration was quantified by a fluorescence polarization immunoassay. Median maximum amikacin concentration and tmax were determined. RESULTS: 1 horse was excluded from analysis because an insufficient volume of synovial fluid for evaluation was obtained at multiple times. The median maximum synovial fluid amikacin concentration was 450.5 µg/mL (range, 304.7 to 930.7 µg/mL), and median tmax was 25 minutes (range, 20 to 30 minutes). All horses had synovial fluid amikacin concentrations ≥ 160 µg/mL (therapeutic concentration for common equine pathogens) at 20 minutes after IVRLP. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that, in healthy horses, maintaining the tourniquet for 20 minutes after IVRLP of amikacin in a saphenous vein was sufficient to achieve therapeutic concentrations of amikacin in the tarsocrural joint.

Do allogeneic bone marrow derived mesenchymal stem cells diminish the inflammatory response to lipopolysaccharide infusion in horses? A pilot study.

Endotoxemia is a leading cause of morbidity and mortality in the equine industry, with colic being the most common cause of endotoxemia in horses. The objective of this study was to evaluate the safety and potential efficacy of a single dose of allogeneic equine bone marrow derived mesenchymal stem cells (BM-MSCs) in horses after the IV administration of lipopolysaccharide (LPS). Six horses were administered an IV infusion of 30 ng/kg LPS (O55:B5 Escherichia coli) in 500 ml saline over 30 min. Immediately after infusion test horses (n = 3) were administered 100 × 106 allogeneic BM-MSCs diluted in saline IV and control horses (n = 3) were administered saline. Clinicopathological data, pro-inflammatory cytokine measurements and sCD14 concentrations were compared between groups. No adverse reactions were observed in horses administered BM-MSCs intravenously. There were no significant differences between test and control horses with regard to clinicopathological values or pro-inflammatory cytokine production. At no time point did concentrations of sCD14 exceed the reference range in any horse. Results suggest that administration of a single IV dose of freshly cultured MSCs is safe and well-tolerated in horses with induced endotoxemia. Further study to evaluate their efficacy as a potential therapeutic in a larger number of horses with clinical disease is required.

Gene expression of proteolytic systems and growth regulators of skeletal muscle in horses with myopathy associated with pituitary pars intermedia dysfunction.

OBJECTIVE: To investigate gene expression of the major proteolytic systems and growth regulators in skeletal muscle of horses with myopathy associated with pituitary pars intermedia dysfunction (PPID). ANIMALS: 14 horses with PPID-associated myopathy and 7 healthy control horses. PROCEDURES: Horses with PPID and controls were age matched (15 to 28 years old). Muscle biopsy specimens were collected from both groups and processed for RNA and cDNA extraction. Validation of the most stable housekeeping genes for skeletal muscle was performed and used to compare gene expression of the following proteolytic systems: cysteine aspartate protease-dependent systems (caspases), lysosomal-dependent systems (cathepsins), non-lysosomal calcium protease-dependent systems (calpains), and ubiquitin-proteasome-dependent systems (ubiquitins). Gene expression of negative regulators of muscle growth (myostatin and inflammatory cytokines interleukin-1beta, interleukin-6, and tumor necrosis factor-alpha) was also determined. RESULTS: No significant difference between groups was detected in expression of the major proteolytic systems except for m-calpain, which was greater in horses with PPID. No differences in gene expression of myostatin and interleukin-1beta, interleukin-6, and tumor necrosis factor-alpha were detected between groups. CONCLUSIONS AND CLINICAL RELEVANCE: Greater expression of m-calpain may suggest that calpains play an important role in development of muscle atrophy in horses with PPID. However, because posttranslational events may alter protein activation, inactivation, and functions not studied here, other mechanisms of muscle atrophy cannot be excluded.