The purpose of this study was to evaluate the cardiopulmonary effects of anesthetic induction with diazepam/ketamine or xylazine/ketamine with subsequent maintenance of anesthesia using isoflurane in foals undergoing abdominal surgery. Seventeen foals underwent laparotomy at 7–10 days of age and a laparoscopy 7–10 days later. Foals were randomly assigned to receive xylazine (0.8 mg kg−1)/ketamine (2 mg kg−1) (X/K)(n = 9) or diazepam (0.2 mg kg−1)/ketamine (2 mg kg−1) (D/K)(n = 8) for induction of anesthesia for both procedures. In all foals, anesthesia was maintained with isoflurane in oxygen with the inspired concentration adjusted to achieve adequate depth of anesthesia as assessed by an individual blinded to the treatments. IPPV was employed throughout using a tidal volume of 10 mL kg−1 adjusting the frequency to maintain eucapnia (PaCO2 35–45 mm Hg, 4.7–6.0 kPa). Cardiopulmonary variables were measured after induction of anesthesia prior to, during, and following surgery. To compare the measured cardiopulmonary variables between the two anesthetic regimes for both surgical procedures, results were analyzed using a three-way factorial anova for repeated measures (p < 0.05). During anesthesia for laparotomy, mean CI and MAP ranged from 110 to 180 mL kg−1 minute−1 and 57–81 mm Hg, respectively, in the D/K foals and 98–171 mL kg−1 minute−1 and 50–66 mm Hg in the X/K foals. Overall, CI, HR, SAP, DAP, and MAP were significantly higher in foals in the D/K group versus the X/K group during this anesthetic period. During anesthesia for laparoscopy, mean CI and MBP ranged from 85 to 165 mL kg−1 minute−1 and 67–83 mm Hg, respectively, in the D/K group, and 98–171 mL kg−1 minute−1 and 48–67 mm Hg in the X/K group. Only HR, SAP, DAP, and MAP were significantly higher in the D/K group versus X/K group during this latter anesthetic period. There were no significant differences between groups during either surgical procedure for end-tidal isoflurane, PaO2, PaCO2, or pH. In conclusion, anesthesia of foals for laparotomy and laparoscopy with diazepam/ketamine/isoflurane is associated with less hemodynamic depression than with xylazine/ketamine/isoflurane.

Objectives—To describe the outcome after arthroscopic electrosurgical excision of axial osteochondral (OC) fragments of the proximal plantar aspect of the 1st phalanx (P1) in horses.Study Design—Retrospective study.Population—Twenty‐three Standardbred racehorses.Methods—Medical records of Standardbred racehorses that had arthroscopic dissection of axial OC fragments of the proximal plantar aspect of P1 with electrocautery probes were reviewed. Horses were positioned in dorsal recumbency; a 1.5% glycine solution was used to maintain joint distension. The arthroscope portal was in the proximal plantar joint pouch and OC fragments were approached using either an ipsilateral or a contralateral triangulation technique. Dissection of the fibrous attachments was performed using loop and hook electrocautery probes. Follow‐up was obtained by telephone questionnaire of owners or trainers and examination of race summary records.Results—Thirty‐three axial OC fragments were removed from 28 metatarsophalangeal joints (left, 14; right, 14). No major operative or postoperative complications occurred. Seven of 8 (79%) of horses that raced before surgery raced after surgery. Thirty‐six percent (n=4) of horses that had not raced before surgery raced after surgery.Conclusion—Intra‐articular electrosurgery is a safe, easy alternative to conventional excision of axial OC fragments of the proximal plantar aspect of P1.Clinical Relevance—Arthroscopic excision using electrocautery probes is a valid alternate method for removal of axial OC fragments of the proximal plantar aspect of P1. In addition, the dorsal recumbency position facilitates removal of several fragments and multiple joint surgery.

OBJECTIVE:To report tissue gentamicin concentrations after intraosseous (IO) perfusion in standing horses.STUDY DESIGN:In vivo study.ANIMALS OR SAMPLE POPULATION:Twelve horses.METHODS:Sedated horses had a cannulated cortical bone screw inserted into the dorsolateral aspect of the treated metacarpus and a tourniquet applied proximally. Gentamicin (2.2 mg/kg) diluted in sterile saline solution (0.1 mL/kg) was infused through the screw. Two horses were euthanatized at each time interval: 0, 2, 6, 12, 24, and 36 hours. Synovial fluid and bone samples were collected distal to the screw from both forelimbs. Gentamicin concentrations were measured using fluorescence polarization immunoassay.RESULTS:The highest synovial fluid gentamicin concentrations were 385+/-273 microg/mL (mean+/-SD) in the metacarpophalangeal joint, 225+/-205 microg/mL in the proximal interphalangeal joint, 215+/-205 microg/mL in the distal interphalangeal joint, 382+/-195 microg/mL in the digital flexor tendon sheath, and 206+/-161 microg/mL in the navicular bursa. The highest bone concentrations of gentamicin were 55+/-30 microg/g in the distal metacarpus, 34+/-27 microg/g in the proximal, 16+/-15 microg/g in the middle, and 16+/-2.2 microg/g in the distal phalanges, and 27+/-17 microg/g in the proximal and 24+/-11 microg/g in the distal sesamoid bones.CONCLUSION:Standing IO perfusion of gentamicin resulted in local antibiotic concentrations in the synovial structures and bones of the distal aspect of the limb that exceed the reported minimum inhibitory concentration of pathogens commonly implicated in equine orthopedic infections.CLINICAL RELEVANCE:Standing IO perfusion of gentamicin in the distal aspect of the limb should be considered for treatment of orthopedic infections of this region in horses.

Introduction: The success of an orthopaedic implant depends on several factors, such as implant material properties, design and fixation technique as well as bone apposition around the implant. Polyetheretherketone (PEEK) is a composite thermoplastic biomaterial exhibiting biochemical and biomechanical properties suitable for load-bearing orthopaedic implants. Two advantages of carbon fibre reinforced PEEK (CFR PEEK) is its increased biomechanical properties and superior wear resistance. These properties are required for long-term orthopedic implants such as joint prosthesis and spinal cages. However the hydrophobic surface of CFR PEEK implants induces the deposition of a peri-implant fibrous capsule preventing bone apposition which is unfavourable for stable anchorage of implants. Nevertheless this tissue reaction can be avoided by coating PEEK implants with materials known to encourage bone tissue ongrowth such as hydroxyapatite or titanium. Vacuum-plasma sprayed (VPS) titanium coatings have been successfully applied on CFR PEEK implants and it has been suggested that the biological performance of these coating should be investigated in vivo (Ha 1997). The objectives of the present study was to compare the bone apposition on uncoated CFR PEEK screws to VPS Titanium coated CFR PEEK screws by investigating implant torque removal and bone/implant contact area. We hypothesized that VPS titanium coated implants would have an increased torque removal and increased bone implant contact area when compared to uncoated CFR PEEK screws. Materials and Methods: Twenty healthy mature adult female Swiss Alpine Sheep were included in this study. They were part of a larger study investigating bone healing using a tibia critical size defect model. In this model, a 7-hole custom made CFR PEEK plate and a 7 hole LCP were applied on the medial and cranial aspect of the tibia respectively. The CFR PEEK plate was locked with randomly chosen uncoated or VPS titanium coated CFR PEEK screws. Screw treatment was alternated between the two proximal and two distal holes of the CFR PEEK plate (the middle three holes remained empty). The sheep were euthanized 6 months postoperatively. The proximal screws were left in situ for histomorphometric analysis and torque removal measurements were performed on remaining screws using a Mecmesin AFTI torque-screwdriver (Mecmesin, Slinfold, UK), equipped with a 10Nm torque-cell. Data were captured at 100Hz and the peak torque was recorded. Longitudinal sections of screws were fixed, dehydrated and embedded in methyl methacrylate. Sections (200 μm) were then cut, glued onto plastic opaque slides, ground down to a thickness of 80 μm and stained with Giemsa Eosin. Digital measurements of tissue/screw and bone/screw interface were recorded for each screw and percentage bone ongrowth was calculated. Torque removal data and the percentage of bone on growth were compared between uncoated and VPS titanium coated screws using a Student t-test. P < 0.05 was considered significant. Results: Torque measurements: The mean torque removal of the titanium VPS coated screws was significantly greater than that of uncoated screws (4.97 ± 1.54 Nm versus 2.3 ± 0.81 Nm; P< 0.001). None of the uncoated screws failed during torque removal and all the coated screws failed during torque removal. Histology: the VPS titanium coated CF PEEK screws had a significantly higher percentage of bone/screw interface than uncoated CF PEEK screws (50% versus 1%; P<0.001) markedly more bone on growth compared to non coated CF PEEK screws. Discussion: CF PEEK is becoming more frequently used in orthopaedics and traumatology due to its favourable characteristics despite poor bone ongrowth to the implants. Modifying the surface of the implant can expand the indications for CFR PEEK to include situations where good bone ongrowth is required. In this study VPS titanium coating was successful in modifying the surface to improve bone ongrowth.

OBJECTIVE:To establish whether hydroxyapatite (HA) coatings applied to metal total-hip-replacement components increased synovitis in the coxofemoral joint of dogs. Study Design-An in vivo research trial and histologic study.ANIMALS:Twenty-three large, mixed-breed dogs.METHODS:Arthroplasty components were implanted with HA on neither stem nor cup, or with HA applied to either the femoral component or with both stem and cup having HA applied in 23 dogs. Synovial inflammation was scored 3, 6, and 12 months after surgery. Synovial membrane thickness; polyethylene particulate load; fibrin exudate; membrane edema; mitotic index; giant-cell, mononuclear histiocyte, lymphocyte, and polymorph number; and collagen degeneration were scored and statistical analyses performed.RESULTS:Operated-side synovial thickness was greatly increased relative to control. Fibrin deposition, intramembranous edema, and collagen degeneration were similar within each time interval among the various component groups. The majority of inflammatory scores among the groups were unchanged. In this 12-month study, the presence of HA coatings appear not to have a marked impact on the development of synovial inflammation.CONCLUSIONS:HA-coated components do appear to contribute somewhat to the inflammatory load within the periprosthetic environment, but this effect is not marked.CLINICAL RELEVANCE:The major advantage of HA addition to arthroplasty components is enhanced osteoconductivity around metallic surfaces. The slight increase in particulate load seen in the presence of HA coatings may contribute to the development of aseptic loosening of arthroplasty components, but is unlikely to be the major causative factor.

In vivo the effects of intra-articular (IA) corticosteroids on articular cartilage remain controversial. This study was designed to examine this issue using synovial fluid (SF) markers of cartilage metabolism. Paired radiocarpal joints, without clinical or radiographic signs of joint disease, were studied in 10 adult horses. Aseptic arthrocentesis was performed weekly for 13 weeks. IA injections of methylprednisolone acetate (MPA) into the treatment joint and the vehicle into the control joint were performed at weeks 3, 5 and 7. We used radioimmunoassays on SF samples which measure a keratan sulfate epitope (KS) and the 846 epitope on cartilage aggrecan (PG) and the C-propeptide (CPII) of cartilage type II procollagen which is released following synthesis of this molecule. Gel chromatography was performed on selected SF samples to evaluate the sizes of SF PG molecules. The total joint KS and the 846 epitopes were both present on a heterogeneous population of mainly molecules which, from chromotographic analysis, appeared to be mainly fragments of the articular cartilage aggrecan. They were significantly elevated in MPA joints whereas CPII was significantly reduced compared to the control during the treatment period. These results indicate that the repeated use of IA MPA leads to a potentially harmful inhibition of procollagen II synthesis and an increased release of degradation products of the PG aggrecan from articular cartilage.

The etiology and pathophysiology of osteochondrosis remain poorly understood because it is difficult to obtain material from lesions in the early stage of this disease and because there is no satisfactory experimental animal model. We wished to determine whether there are changes in articular cartilage turnover in equine osteochondrosis, which closely resembles the human disease, by assaying cartilage matrix molecules in synovial fluids. We used immunoassays that measure a keratan sulfate epitope and the epitope 846 on the cartilage proteoglycan aggrecan and the C‐propeptide of cartilage type‐II procollagen, which is released following the synthesis of this molecule, to analyse synovial fluids from equine tarsocrural joints with and without osteochondrosis. In young horses with osteochondrosis, there was a significant increase of C‐propeptide of type‐II procollagen accompanied by a decrease in the 846 and keratan sulfate epitopes. The results identify differential alterations in aggrecan and type‐II collagen turnover in the cartilage matrix in young animals with osteochondrosis that may contribute to the pathological degeneration of articular cartilage in this disease.

Summary An 18-month-old 420 kg Standardbred colt was admitted for removal of three type I proximal plantar osteochondral fragments of the proximal phalanx. An electrocautery loop probe was used for the arthroscopic removal of the osteochondral fragments. Distension of the metatarsophalangeal joints was achieved using a 1.5% glycine solution. Under arthroscopic guidance, the soft tissue attachments of the osteochondral fragments were transected with the electrocautery loop probe. Once freed of all soft tissue attachments, the fragments were removed with a Ferris-Smith intervertebral disc rongeur. The electrocautery loop probe permitted an easy, precise and smooth dissection of intra-articular soft-tissue structures. Six weeks after the operation, the colt had returned to training. After eight months, the colt remained sound and was racing. The loop electrocautery probe was used as an alternative to manual sharp instruments in the arthroscopic treatment of Type I proximal plantar osteochondral fragments of the proximal phalanx. An electrocautery loop probe was used in the arthroscopic treatment of type I proximal plantar osteochondral fragments of the proximal hind phalanx in a Standardbred horse. The loop electrocautery probe was used as an alternative to manual sharp instruments.

OBJECTIVE:To develop a technique for arthroscopic excision of apical sesamoid fracture fragments using electrocautery probes.ANIMALS OR SAMPLE POPULATION:A total of 18 Standardbred horses.METHODS:Arthroscopic removal of apical sesamoid fracture fragments using both hook and loop electrocautery probes was performed on 18 Standardbred horses. The fracture fragments were approached using either an ipsilateral (3) or contralateral (15) arthroscopic triangulation technique. Distension of the metacarpo- (metatarso)-phalangeal joints was achieved using a 1.5% glycine solution. Under arthroscopic guidance, both the suspensory and intersesamoidean ligament attachments to the abaxial and the axial margins of the apical fragment were transected using a hook electrocautery probe. Subsequently, the palmar (plantar) soft tissue attachments to the apical fragment were transected with a loop electrocautery probe. Once freed of soft tissue attachments, the apical fragment was removed with Ferris-Smith intervertebral disc rongeur. The arthroscopic portals were closed in a routine manner.RESULTS:Horse ages ranged from 2 to 8 years (median, 2.5 years). Eighteen apical sesamoid fracture fragments were removed from the left (8) and right (8) hind limbs and the left (1) and right (1) forelimbs. Apical fragments occured in 15 lateral and 3 medial proximal sesamoid bones. No major complications occurred during or after surgery. The electrocautery probes permitted an easy and precise dissection of all soft tissue attachments to the apical sesamoid fracture fragments in all horses. Follow-up time was 7 to 44 months (median, 26 months); 10 of 14 horses returned to racing. Seven of nine horses that raced before surgery raced again and three of five that had not raced before surgery, raced afterwards.CONCLUSION:Arthroscopic excision of apical sesamoid fracture fragments can be accomplished arthroscopically using electrocautery probes.CLINICAL RELEVANCE:Arthroscopic electrosurgery is an efficient and safe alternative for intra-articular dissection in horses.

Exploratory laparoscopy of the right dorsal portion of the abdominal cavity was performed on a Standardbred filly because of signs of mild abdominal pain of 7 days' duration. On the basis of clinical examination, diagnosis was suppurative peritonitis, abdominal adhesions in the area of the right ovary, and right displacement and impaction of the pelvic flexure of the ascending colon. During laparoscopy, an abdominal adhesion between the right uterine horn, the cecum, and the pelvic flexure was identified. The abdominal adhesions were either stretched with laparoscopic forceps used as a probe or dissected bluntly with the tips of a pair of 10-mm laparoscopic Kelly forceps. Antibiotics were administered for 21 days after surgery. The horse fully recovered and raced 11 months after the surgery.

Objective —The purposes of this study were to develop a technique of paralumbar fossa laparoscopic ovariectomy using Endoloop ligatures and to avoid a laparotomy incision for ovary removal by using a 33–mm diameter muscle spreader trocar‐cannula unit. Animals or Sample Population —Seven mares. Methods —Bilateral laparoscopic ovariectomy was performed under general anesthesia in two horses and under neuroleptanalgesia and local anesthesia in five standing mares. Ovaries were approached from the ipsilateral paralumbar fossa through two portal sites located in the paralumbar fossa and a third between the 17th and 18th ribs. Insufflation of the abdominal cavity was achieved using an automatic carbon dioxide insufflator. Two Endoloop ligatures were placed on the mesovarium. The cannula, located in the center of the paralumbar fossa, was removed, and a 33‐mm diameter trocar‐cannula unit, with a cone‐shaped muscle spreader extremity, was inserted through the same portal. The mesovarium was transected between the ovary and the ligatures. The ovaries were removed from the abdomen through the 33‐mm diameter cannula. The abdominal wall was closed in a routine manner. Results —No major complications occurred during or after surgery. Conclusion —Paralumbar fossa laparoscopic ovariectomy in mares using Endoloop ligatures and the 33‐mm diameter trocar‐cannula unit was an effective technique for ovariectomy of normal ovaries in this study. Clinical Relevance —Endoloop ligatures provide a viable alternative for laparoscopic ligation of ovarian pedicles in mares.

Eleven foals (nine cadavers and two anesthetized) positioned in dorsal recumbency were examined to describe normal abdominal anatomy viewed by laparoscopy. The foals ages ranged from 1 to 150 days. Insertion sites were selected for a Verres needle, laparoscope and instrument portals to avoid trauma to the umbilical structures. The abdominal cavity was insufflated to a pressure of 10 to 12 mm Hg using an automatic carbon dioxide insufflator. Laparoscopic examination allowed excellent observation of the umbilical structures, the bladder, the genital tract, the inguinal area, the liver and segments of the intestinal tract in all foals. However, the duodenum and ileum were not identified. An embryonic vestige of the yolk stalk (ductus pedunculi vitellini) was identified in six foals. In four foals, this appeared as a fibrous band extending from the umbilicus to the cranial abdominal cavity where it inserted on the small intestine. In two foals only the fibrous umbilical portion of the band was observed.

INTRODUCTION: The use of conventional external fixators (EF) and of the transfixation pin (TP) casts in the treatment of distal limb fractures is often associated with complications in horses. The trickiest is the development of pin loosening, a painful process that exposes the horse to further and frequently fatal pathology like laminitis. The causative mechanism can be found in the considerable bending experienced by conventional pins resulting in pain and critical strains at the inner and outer cortex of a long bone depending on material properties and geometry of the EF components1. A novel pin-sleeve (PS) system