Differential gene expression in skin RNA of horses affected with degenerative suspensory ligament desmitis.

BACKGROUND: Equine degenerative suspensory ligament desmitis (DSLD) is a systemic connective tissue disorder first identified in Peruvian Paso horses but afflicting other horse breeds as well. Inappropriate accumulation of proteoglycans in connective tissues, most prominently in tendons and ligaments, leads to progressive and debilitating lameness and pain. It is largely unknown what drives the overproduction of proteoglycans, but our previous studies suggest involvement of bone morphogenetic protein 2 (BMP2), a member of the transforming growth factor-ß (TGFß) family, impacting synthesis of proteoglycans. To identify potential players in pathogenesis of DSLD a new approach utilizing next generation sequencing was undertaken. METHODS: Next generation sequencing was performed using RNA extracted from skin biopsies of six control Peruvian Pasos and six horses with DSLD (4 Peruvian Pasos and 2 warmbloods). The CuffDiff result sets were validated with algorithms used to run them. This was based on the determined false discovery rates derived from the P values adjusted for multiple testing for any given result. RESULTS: Bioinformatics analysis of transcriptomes revealed differential expression of over 1500 genes, including increased expression of genes for several growth factors (most prominently BMP2, FGF5, CTGF, many members of the EGF family), and mediators of signaling (Fos, Myc, MAPK system), and keratins. Two genes encoding for enzymes involved in synthesis of hyaluronan were also overexpressed. Gene expression was decreased for protein cores of many proteoglycans, several growth factors, most collagens, and many peptides with immune function. CONCLUSIONS: The overexpression of BMP2 correlates well with our previous data. However, the decrease in expression of numerous proteoglycans was unexpected. A mutation in a gene of a less characterized proteoglycan and/or glycosyltransferase with subsequent increased production of hyaluronan and/or a proteoglycan(s) undetected in our study could account for the systemic proteoglycan deposition. Decreased collagen gene expression indicates abnormal connective tissue metabolism. The increased expression of keratin genes and FGF5 supports reports of skin abnormalities in DSLD. Underexpression of immune function genes corresponds with lack of inflammation in DSLD tissues. Finally, though the proteoglycan and/or glycosaminoglycan abundant in DSLD has not been identified, we validated our previous data, including overexpression of BMP2, and systemic nature of DSLD due to disturbed metabolism of the extracellular matrix.

Clinical study evaluating the accuracy of injecting the distal tarsal joints in the horse.

BACKGROUND: Osteoarthritis (OA) of the centrodistal (CD) and tarsometatarsal (TMT) joints is a common cause of lameness in horses. Intra-articular diagnostic anaesthesia and/or therapeutic injection are relied upon to help diagnose and treat many horses with OA of these joints. OBJECTIVES: The objective of this study was to determine the accuracy of arthrocentesis of the CD and TMT joints using a sample population of equine surgeons and surgery residents. STUDY DESIGN: Randomised experimental study. METHODS: Six operators each injected four CD and four TMT joints in 12 sedated horses. The operators were randomly assigned to inject either the left CD and right TMT or the right CD and left TMT on four randomly assigned horses. The joints were injected with a 4 ml solution of contrast medium (2 ml), sterile saline (1.5 ml) and amikacin (0.5 ml). A minimum of two radiographs of each joint was obtained to evaluate the presence of contrast medium within the target joint. RESULTS: The TMT joint was successfully injected in 23/24 joints (96% accuracy). The CD joint was successfully injected in 10/24 joints (42% accuracy). Communication between the TMT and CD joints was visible in 26% of successful TMT injections. Communication between the CD and TMT joints was visible in 20% of successful CD injections. MAIN LIMITATIONS: Despite specific requests to do so, we were unable to standardise the injection technique across all operators. CONCLUSIONS: The accuracy of injecting the TMT and CD joints of sedated horses was 96 and 42%, respectively. The CD joint was frequently missed with contrast medium being placed in the periarticular tissues. These data support the clinical impression of the difficulty of injecting the CD joint and suggests that practitioners should utilise ancillary methods, such as radiographs, to ensure proper needle placement.

Ex vivo comparison of three hand sewn end-to-end anastomoses in normal equine jejunum.

REASONS FOR PERFORMING STUDY: Although single layer techniques are preferred in man and small animals for small intestinal end-to-end anastomoses, double layer techniques are more popular in equine surgery. This study was undertaken to evaluate the ex vivo characteristics of 2 single layer anastomoses in comparison to the traditionally performed double layer anastomosis in equine jejunum. OBJECTIVES: To compare ex vivo: 1) construction time; 2) bursting pressure; and 3) lumen size reduction of 3 suture patterns (double layer simple continuous/Cushing pattern [2C]; single layer Lembert pattern [1L]; and single layer Cushing pattern [1C]) for end-to-end equine jejunojejunostomies. METHODS: End-to-end jejunojejunostomies were constructed using 2C (n = 7), 1L (n = 7) and 1C (n = 7) in harvested equine jejunum and construction times were recorded. Anastomosed and control segments were distended with gas until failure. Intraluminal pressure at failure and mode of failure were recorded. Lumen size reduction was calculated as a percentage decrease from control jejunum. Results were compared using an ANOVA and P<0.05 was considered significant. RESULTS: The 1C anastomoses were faster to construct than the 1L anastomoses, which were faster to construct than the 2C anastomoses. There were no differences in bursting pressures between the different anastomoses and control jejunum. All anastomoses decreased lumen size from control values but there were no differences in lumen reduction between types of anastomoses. CONCLUSIONS: Single layer anastomoses are faster to construct than double layer anastomoses, with the 1C being fastest. Single layer anastomoses are as strong and result in comparable lumen size reduction as traditional 2C anastomoses. POTENTIAL RELEVANCE: As the 1C anastomosis results in less exposed potentially adhesiogenic suture material than the 1L while providing adequate strength and similar luminal size reduction, the 1C may be better for equine small intestine anastomosis and further in vivo studies are warranted.

The effect of uterine torsion on mare and foal survival: a retrospective study, 1985--2005.

REASONS FOR PERFORMING STUDY: Anecdotal speculation suggests that prognosis for survival of mares and foals following correction of uterine torsion has improved over the past 30 years. OBJECTIVES: To determine statistically the outcome of uterine torsion according to duration of clinical signs, stage of gestation, parity, physical examination findings, method of correction, prognosis for survival and reproductive health of the mare, and prospects for the foal within the neonatal period. METHODS: This retrospective study combined cases from 4 equine referral hospitals. RESULTS: The stage of gestation at which uterine torsion occurred was a risk factor for survival of mare and foal. Overall mare survival was 53/63 (84%); when uterine torsion occurred at < 320 days gestation, 36/37 (97%) of mares survived compared to 17/26 (65%) survival rate when uterine torsion occurred at > or = 320 days gestation. Overall foal survival was 54% (29/54). When uterine torsion occurred at < 320 days gestation, 21/29 (72%) foals survived compared to 8/25 (32%) when uterine torsion occurred at > or = 320 days gestation. Thirty mares were discharged from the hospital carrying a viable fetus following uterine torsion correction and 25/30 (83%) of these mares delivered live foals that survived beyond the neonatal period. CONCLUSIONS: Prognosis for survival for mares and foals following uterine torsion is good and improves if torsion occurs < 320 days compared to > or = 320 days gestation. CLINICAL RELEVANCE: Gestational timing of uterine torsion should be considered when advising clients about the prognosis for survival of the mare and foal. The prognosis for a mare delivering a live foal is good if the mare is discharged from the hospital following uterine torsion correction with a viable fetus.

The effect of enrofloxacin on cell proliferation and proteoglycans in horse tendon cells.

Fluoroquinolone antibiotics have been used widely in humans and domestic animals, including horses, because of their broad-spectrum bactericidal activity, and relative safety. The use of fluoroquinolones, however, is not without risk. Tendonitis and spontaneous tendon rupture have been reported in people during or following therapy with fluoroquinolones. We have studied the effects of enrofloxacin, a fluoroquinolone antibiotic used commonly in domestic animals, on tendon cell cultures established from equine superficial digital flexor tendons. Effects on cell proliferation and morphology were studied using cell counting and scanning electron microscopy. Monosaccharide content and composition was determined by gas chromatography-mass spectrometry analysis. Western and Northern blot analyses were utilized to evaluate the synthesis and expression of two proteoglycans, biglycan and decorin. Our data demonstrate that enrofloxacin inhibits cell proliferation, induces morphological changes, decreases total monosacharide content and alters small proteoglycan synthesis at the glycosylation level in equine tendon cell cultures. These effects are more pronounced in juvenile tendon cells than in adult equine tendon cells. We hypothesize that morphological changes and inhibition of cell proliferation are a result of impaired production of biglycan and decorin, proteoglycans involved in fibrillogenesis of collagen, the most important structural component of the tendon of enrofloxacin-treated tendon cells. Our findings suggest that fluoroquinolones should be used with caution in horses, especially in foals.