P.O. Eric Mueller

Dental Disease in Geriatric Horses

The dental management of geriatric horses can be a rewarding challenge to the practitioner. Owners become dissatisfied when their expectations are unrealistic. Consequently, communication between the owner and the practitioner is essential prior to the start of any dental procedure in a geriatric horse. Owners often expect the practitioner to correct what has been neglected for years. It is critical that the owner understand the possible complications associated with dental procedures and that some procedures (e.g., trephination) may necessitate protracted care. Often, when a tooth has been removed, there is a need for more frequent masticatory examinations to curtail any potential problems (i.e., development of step mouth). The owner needs to be aware of the extra dental maintenance costs that must be included in the upkeep of the horse.

Glycan profiling of a defect in decorin glycosylation in equine systemic proteoglycan accumulation, a potential model of progeroid form of Ehlers-Danlos syndrome

Defects in glycosylation of decorin can result in systemic hereditary disease. A mutation in the galactosyl transferase I gene is the underlying defect of a progeroid form of Ehlers-Danlos syndrome. We have previously described pathological changes in equine systemic proteoglycan accumulation (ESPA, formerly degenerative suspensory ligament desmitis) as consisting of excessive presence of decorin and other proteoglycans in organs and structures with a high content of connective tissue. Using liquid chromatography/mass spectrometry, and one- and two-dimensional immunoblotting we have determined that decorin from ESPA-tendons had a higher molecular weight than decorin from non-affected control tendons. Glycosaminoglycan structure and monosaccharide composition were determined with HPLC analysis of chondroitinase ABC-digested glycosaminoglycans and gas chromatography/mass spectrometry. This analysis revealed an increase in the total content of sulfated disaccharides, particularly due to enhanced sulfation at 6-position of N-acetyl galactosamine (GalNAc) with a subsequent decrease in the ratio of 4-sulfation to 6-sulfation disaccharides in the ESPA decorin. The ESPA-affected decorin also exhibited altered biological activity resulting in (1) diminished binding of TGFbeta1 (and of anti-decorin antibody) to ESPA decorin, and (2) increased expression of TGFbeta1 in ESPA tissues.

Instrumentation and Techniques in Equine Gastrointestinal Surgery

Recent advances in abdominal surgical techniques in the horse have resulted in improved survival rates and reduced postoperative morbidity. The development of abdominal surgical procedures in horses has paralleled the development of safe anesthetic protocols and innovative technological advancements in humans. Irrespective of the species, the application of sound surgical principles is still the foundation of surgical intervention. This article describes recent advances in equine gastrointestinal surgical techniques. The availability and application of innovative intestinal surgical devices and their specific uses in equine gastrointestinal surgery are also described.

Dental embryology, anatomy, development, and aging.

Equine practitioners should be knowledgeable of dental anatomy and development to enhance their skill of age estimation of horses. The permanent teeth of horses are continually undergoing changes in shape and appearance. These changes may be used to suggest a reasonable age range for a horse.

In vitro comparison of a single-layer (continuous Lembert) versus two-layer (simple continuous/Cushing) hand-sewn end-to-end jejunoileal anastomosis in normal equine small intestine.

Objectives To compare in vitro physical and mechanical characteristics of 1-layer and 2-layer end-to-end jejunoileostomy. Study Design In vitro experimental study. Animals Adult horses (n = 6). Methods Harvested equine jejunum and ileum was used to create 1- and 2-layer end-to-end jejunoileostomy specimens. Construction time, bursting pressure, and relative lumen diameter (anastomosis diameter expressed as a percentage of the lumen diameter of adjacent jejunum and ileum) were compared. Construction time and relative lumen diameters were compared using a paired t-test. Bursting pressure for anastomoses and control jejunal segments were compared using a repeated-measure ANOVA. Statistical significance was set at P < .05. Results Mean (±SEM) construct completion times were shorter for 1 layer (21 ± 0.91 minutes) than 2 layers (26.71±1.16 minutes; P = .005). Relative lumen diameters (percentage of jejunal diameter) were larger for 1 layer (77.67 ± 4.46%) than for 2 layers (69.37 ± 2.8%; P = .035). There were no significant differences in bursting pressures between the 2 groups and the control jejunum (P =.155) or relative lumen diameters (percentage of ileal diameter; P =.118). Conclusions One-layer jejunoileostomy can be created in a shorter time and maintain a larger anastomosis luminal diameter without compromising maximum bursting pressure when compared to 2-layer jejunoileostomy.OBJECTIVES To compare in vitro physical and mechanical characteristics of 1-layer and 2-layer end-to-end jejunoileostomy. STUDY DESIGN In vitro experimental study. ANIMALS Adult horses (n = 6). METHODS Harvested equine jejunum and ileum was used to create 1- and 2-layer end-to-end jejunoileostomy specimens. Construction time, bursting pressure, and relative lumen diameter (anastomosis diameter expressed as a percentage of the lumen diameter of adjacent jejunum and ileum) were compared. Construction time and relative lumen diameters were compared using a paired t-test. Bursting pressure for anastomoses and control jejunal segments were compared using a repeated-measure ANOVA. Statistical significance was set at P < .05. RESULTS Mean (± SEM) construct completion times were shorter for 1 layer (21 ± 0.91 minutes) than 2 layers (26.71 ± 1.16 minutes; P = .005). Relative lumen diameters (percentage of jejunal diameter) were larger for 1 layer (77.67 ± 4.46%) than for 2 layers (69.37 ± 2.8%; P = .035). There were no significant differences in bursting pressures between the 2 groups and the control jejunum (P =.155) or relative lumen diameters (percentage of ileal diameter; P =.118). CONCLUSIONS One-layer jejunoileostomy can be created in a shorter time and maintain a larger anastomosis luminal diameter without compromising maximum bursting pressure when compared to 2-layer jejunoileostomy.

Comparison of Tensile Strength and Early Healing of Acute Repeat Celiotomy Through a Ventral Median or a Right Ventral Paramedian Approach

OBJECTIVE To compare tensile strength, failure location, and histologic features after acute repeat celiotomy through a ventral median (RVM) or a right ventral paramedian (RVP) celiotomy in horses. STUDY DESIGN Ex vivo experimental study. ANIMALS Adult horses (N = 18). METHODS Twelve adult horses had original ventral median (OVM) celiotomy. Repeat celiotomy was performed 72 hours postoperatively through the original ventral median (RVM, N = 6) or a RVP (N = 6) celiotomy. Celiotomies were scored daily for edema, drainage, and dehiscence. Fourteen days after repeat celiotomy, horses were euthanatized and abdominal wall containing celiotomy(ies) were collected for biomechanical and histological evaluation. The abdominal wall of control horses (N = 6; no celiotomy) was collected for biomechanical testing. Vital sign variables, incisional edema, and histologic scores were compared using a Wilcoxon signed-rank test. Incisional fibrotic depth and tensile strength per unit length (N/cm) was compared using repeated measures ANOVA. RESULTS RVM and RVP horses had significantly less tensile strength compared to control horses, but no differences were observed between RVM and RVP horses. No differences in healing, inflammation, infection, or necrosis of repeat celiotomies was observed, but RVP horses accumulated more fibrin and hemorrhage within the incision. RVP horses had significantly greater incisional edema scores, but incisional drainage was more frequent in RVM horses. CONCLUSIONS Acute repeat celiotomy through a RVM incision results in similar incisional healing and tensile strength compared with repeat celiotomy through a RVP incision.

Contribution of tumor necrosis factor alpha to endotoxin-induced mucosal dysfunction in the feline jejunum

Tumor necrosis factor α (TNFα) occupies a pivotal role in the development of shock and tissue injury during endotoxemia and septicemia, and may be an important trigger in the pathogenesis of endotoxin-induced intestinal mucosal dysfunction. This study investigated the contribution of TNFα to endotoxin-induced mucosal dysfunction and the efficacy of polyclonal anti-TNFα antibody in preventing endotoxin-induced mucosal dysfunction. To evaluate mucosal dysfunction, jejunal blood-to-lumen clearances of chromium 51-labeled ethylenediaminetetraacetate ([51Cr]-EDTA) were measured in cats administered fetal calf serum (controls), endotoxin, TNFα, or polyclonal anti-TNFα antibody and endotoxin. Serum TNFα activity was determined using a modified in vitro cytotoxicity bioassay using the murine fibrosarcoma cell line, WEHI-164 clone 13. Endotoxin and TNFα induced jejunal mucosal dysfunction as indicated by increases in [51 Cr]-EDTA clearance. Mucosal dysfunction was accompanied by marked increases in serum TNFα activity. Furthermore, pretreatment with polyclonal anti-TNFα antibody prevented endotoxin-induced mucosal dysfunction and markedly reduced the associated increase in serum TNFα activity. The findings of this study suggest that TNFα is an important mediator of endotoxin-induced mucosal epithelial barrier dysfunction.

Ex Vivo Mechanical Evaluation of a Sternal ZipFix® Implant for Prosthetic Laryngoplasty in Horses

OBJECTIVE To evaluate the properties of a ZipFix(®) (ZipFix) implant in equine laryngeal cartilages. STUDY DESIGN Ex vivo biomechanical study. SAMPLE POPULATION Equine arytenoid (n=36) and cricoid cartilages (n=18). METHODS Suture bites were placed in arytenoid or cricoid cartilages using a ZipFix(®) implant or a single strand of USP 5 braided polyester (TiCron™), and arytenoid and cricoid cartilages were separately subjected to single load to failure (25 N preload) or cyclic loading for 1,000 cycles, followed by single load to failure. Load, distraction, and stiffness were recorded. RESULTS Four arytenoid-ZipFix cartilages fractured on implant placement. Under single load, arytenoid-ZipFix (n=9) failed at a greater mean load (359.01 ± 57.98 N) than arytenoid-Ticron (159.11 ± 22.98 N; n=12; P<.001). Arytenoid-ZipFix stiffness (31.32 ± 4.26 N/mm) was significantly greater than arytenoid-Ticron (13.18 ± 2.60 N/mm; P<.001). Cricoid-ZipFix stiffness (20.83 ± 3.37 N/mm) was significantly greater than cricoid-Ticron (13.6 ± 3.82 N/mm; n=6; P=.006). Under cyclic load, arytenoid-ZipFix distraction (2.53 ± 0.63 mm; n=5) was significantly less than arytenoid-Ticron (5.06 ± 1.37 mm; n=6, P=.006). After cyclic load, arytenoid-ZipFix failure load (295.16 ± 54.95 N) was significantly greater than arytenoid-Ticron (127.69 ± 32.67 N; P=.002). Arytenoid-ZipFix stiffness (35.59 ± 1.58 N/mm) was significantly greater than arytenoid-Ticron (24.10 ± 6.85 N/mm; P=.019). CONCLUSION In arytenoid cartilages, the sternal ZipFix(®) implant was significantly stronger and stiffer compared to a single strand of Ticron. During placement of the ZipFix(®) implant, frequent arytenoid cartilage failure occurred before testing, suggesting the implant is not suitable for clinical application.

A profile of morbidity and mortality rounds within resident training programs of the American College of Veterinary Surgeons

OBJECTIVE To describe the structure and role of morbidity and mortality rounds (MMR) in resident training programs of the American College of Veterinary Surgeons (ACVS). STUDY DESIGN Cross-sectional analysis: survey. SAMPLE POPULATION ACVS surgical resident program directors. METHODS Electronic surveys consisting of 27 questions were sent to the directors of 142 ACVS resident programs. RESULTS Forty-five (31.6%) programs completed the survey, including 24 (53.3%) from small animal programs and 21 (46.7%) from large animal programs. Thirty-two (71.1%) programs incorporated regular MMR in their training. The primary goal of these rounds was improvement of patient care (63%) and education (31%). Selection of cases was based on unexpected mortality (80%), unexpected morbidity (77.4%), teaching value (65.7%), and review of medical errors (63%). Twenty-six percent of programs reported conducting formal follow-up for topics discussed during MMR. Ninety-five percent of programs believed that MMR were valuable. CONCLUSION MMR are commonly incorporated in surgical resident training programs. The primary objectives of these rounds are to educate residents, refine hospital medical and operational policies, and to improve patient care. The majority of residency programs view MMR as worthwhile. However, the majority of veterinary residency programs fail to follow up MMR with formal initiatives for improvement and objective outcome assessments for issues identified during MMR.

Does BMP2 play a role in the pathogenesis of equine degenerative suspensory ligament desmitis

ObjectiveHorses afflicted with degenerative suspensory ligament desmitis (DSLD) suffer from progressive leg pain and lameness without history of trauma. DSLD is a systemic disorder caused by abnormal accumulation of proteoglycans in many connective tissues. One proteoglycan found in higher quantities in DSLD is decorin. The accumulated decorin has an abnormally glycosylated glycosaminoglycan chain in DSLD. In addition to acellular accumulations of proteoglycans foci of active fibroblasts/tenoblasts were observed in some tendons and suspensory ligaments (SLs) from DSLD cases We have hypothesized that this represents an early event in DSLD and that production of chondrogenic growth factors, such as BMP2, and/or enzyme participating in glycosylation of glycosaminoglycans is a major factor in initiation and progression of DSLD.ResultsUsing immunohistochemistry we have identified BMP2 in these cellular foci, indicating association with proteoglycan production, but not in other cells in the tendon and SLs. In contrast, very little staining for TGFβ and dermatan sulfate epimerase, an enzyme involved in glycosylation of glycosaminoglycan chains, was observed in these foci and other cells in both control and DSLD-affected tendons and SLs. Our data support our hypothesis that chondrogenic growth factors may be responsible, at least in part for progression of DSLD in horses.