Scientific Presentation Abstracts 2009 American College of Veterinary Surgeons Veterinary Symposium October 8–10, Washington, DC Copyright of these abstracts is retained by the authors unless assigned elsewhere by them. Abstracts are listed in alphabetical order by the presenter’s name (underlined) SAFETY OF HYPERTONIC SALINE SOLUTIONS FOR JOINT LAVAGE IN HEALTHY DAIRY CALVES Damien Achard 1 , David Francoz 1 , Andre´ Desrochers 1 , Christiane Girard 2 , Caroline Piche´ 2 . 1 Sciences Cliniques, Faculte´ de Me´ decine Ve´ te´ rinaire, Universite´ de Montre´ al, Saint Hyacinthe, QC, Canada; 2 Pathologie et Microbiologie, Faculte´ de Me´ decine Ve´ te´ rinaire, Universite´ de Montre´ al, Saint Hyacinthe, QC, Canada The objective of this study was to evaluate clinical, cytological and histo- logical effects of a single joint lavage with 7.2% and 15% hypertonic saline solution (HSS) on tarsocrural joints of healthy calves. Lavage of tarsus of 10 calves were randomly performed with 7.2% HSS, 15% HHS and isotonic saline. Synovial fluid (SF) samples were collected aseptically on Day 1 (before joint lavage), Day 2, 3, 4 and 8 for complete cytological analysis. Physical examination, lameness and swelling were re- corded daily. Calves were euthanized on Day 8 for joint histological analyses. Joints irrigated with HSS were more distended then those irrigated with isotonic saline. Slight to moderate lameness and distension were observed in the 15% HSS group. In the 7.2% HSS group, slight distension that rapidly returned to normal was observed. No lameness was detected. In comparison to isotonic saline group, total protein concentration was significantly increased on Day 2 and 3 for the 7.2% HSS group and on Day 2, 3 and 4 for the 15% HSS group. SF total cell count was significantly decreased in the 7.2% group on Day 3 and in the 15% group on Day 2. Histological analysis indicated no abnormalities of joint cartilage but revealed different levels of synovial mem- brane inflammation. Synovitis was more severe in the HSS 15% group. Inflammation was present in all healthy calves joint but was more severe with HSS. Although the use of a 15% HSS is not recommended, 7.2% HSS could be used safely in infected joints. MECHANICAL EVALUATION OF THE EQUINE LARYNGOPLASTY — SINGLE AND CYCLICAL CYCLE TESTING OF THE ARYTENOID AND CRICOID CARTILAGE USING THREE DIFFERENT SUTURE MATERI- ALS Benjamin J. Ahern, Eric J. Parente. Clinical Studies, University of Penn- sylvania, Kennett Square, PA Laryngoplasty failure in horses has been attributed to cartilage and suture failure. This study hypothesized that the muscular process of the arytenoid would fail in single cycle at a lower load than the cricoid for multiple sutures. Further, that neither the suture nor the cartilage would fail under cyclical loading, and that displacement would be greater in the arytenoids. 36 equine cadaver larynges were dissected, embedded in SmoothCast 300Q s and mounted on an Instront. Single strands of #2 Ethilon s , #5 Ethibond s or #5 Fiberwire s were passed through the cartilages and looped to the actuator arm of the Instron. Samples were tested in single cycle load to failure and cyclic loading (10,000 cycles at 3cycles/sec from 0N to 25N). Data was analyzed with an ANOVA and Student t-tests with a significance of Po0.05. Single cycle arytenoid failure was higher for Ethibond s (241.10  47.67N) than Ethilon s (133.85  27.89N) and Fiberwire s (142.67  32.40N). Cricoid load to failure was higher for Ethibond s (220.39  49.11) and Fiberwire s (205.94  48.17) than for Ethilon s (171.93  21.19N). Ethilon s and Fiberwire s had lower failure in the arytenoid compared to the cricoid. Suture pull through the cartilage was not visibly evident during cyclical testing. Displacement of the Ethibond s in the arytenoid (0.43  0.21 mm) was lower than Ethilon s (0.92  0.41 mm). Fiberwire s (0.83  0.43 mm) was not different to Ethi- lon s . Displacement of the Ethibond s in the cricoid (0.45  0.18 mm) was less than both Ethilon (1.04  0.30 mm) and Fiberwire s (0.97  0.45 mm). PERIPHERAL BLOOD APHERESIS, ADIPOSE AND BONE MARROW AS SOURCES OF PLURIPOTENTIAL STEM CELLS IN HORSES Benjamin J. Ahern 1 , Shawn Terkhorn 2 , Karen V. Jackson 3 , Kurt Hankenson 2 , Nicola Mason 3,4 , Dean Richardson 1 , Thomas P. Schaer 1 . 1 Clinical Studies, University of Pennsylvania, Kennett Square, PA, 2 Animal Biology, University of Pennsylvania, Philadelphia, PA, 3 Department of Pathobiology, University of Pennsylvania, Philadelphia, PA, 4 Clinical Studies, University of Pennsylvania, Philadelphia, PA Mesenchymal stem cells are being used in horses for cell based therapies. Peripheral blood can readily be collected and processed via apheresis. Our hypothesis is that mononuclear cells will be increased and red blood cells decreased in the apheresis product (compared to venous blood), and that apheresis product, fat derived cells, and bone marrow (BM) derived cells are capable of adherence and differentiation (adipogenic, chondrogenic and osteogenic lineages) in vitro. We found apheresis product had 203% higher white cell count than peripheral blood, and red blood cell count was 2.2% of peripheral blood (Po0.001). Adherent cells occurred in apheresis product(0%), adipose(100%), and BM(33%). Both treated fat and BM derived cells underwent adipogenesis and chondrogenesis. BM derived treated cells produced more mineral than control cells and adipose derived treated cells (both Po0.001). Apheresis processing was able to concentrate mononuclear cells and reduce RBC. How- ever, the apheresis product was not able to attach and differentiate in this study. LARGE ANIMAL MODEL FOR THE EVALUATION OF SCREW AUGMENTATION MATERIALS Benjamin J. Ahern 1 , Sandra Bostic 1 , Robert Harten 2 , Thomas P. Schaer 1 . 1 Clinical Studies, University of Pennsylvania, Ken- nett Square, PA, 2 Synthes, Synthes, Paoli, PA Internal stabilization often occurs in the presence of compromised bone quality which may require augmentation with biomaterials. There are no clinically relevant and well-described animal models for evaluation of these biomaterials. This study evaluates a model for this purpose. We hypothesized for this model that bone repair would progress to fracture heal- ing and have evidence of load bearing on the augmented sites. Thirty-eight sheep had a unilateral tibial osteotomy repaired with a 4.5 mm 7 hole locking compression plate. Holes 1–3 and 5–6 were filled with locking screws. Hole #7 (distal) was drilled to either 4.5 mm or 8 mm and augmented with a bio- material (PMMA or bone cement). Radiographic (0,6,12 wks) and physical (daily) examinations were completed prior to euthanasia at 12 weeks. Ex vivo analyses consisted of screw tightness evaluation, gross pathology and micro-CT imaging. Thirty-seven animals completed the study. Radio- graphy demonstrated normal bone remodeling in both groups. More screws were ‘‘tight’’ when augmented with PMMA than bone cement. During dissection there was evidence of contact wear between the plate/head inter- face. Micro-CT revealed increased intracortical porosity of the bone proximal to the augmented screws reflecting weight transference. There was no differ- ence in osteotomy healing between groups. This study reports a model for evaluation of biomaterial augmented hardware in bone repair. Our data is strong evidence that this model is a rigorous evaluation of novel augmentative fracture techniques. E23