Castration in the standing horse combining laparoscopic and conventional techniques.

BACKGROUND: Standing laparoscopic castration without orchidectomy has been shown to be a reliable method of castration in animals with abdominal cryptorchidism, but it cannot be recommended as a method of castration in those with inguinal cryptorchidism or normal males. An alternative laparoscopic method for the castration of horses with descended testes was developed. OBJECTIVES: To report the results of laparoscopy-assisted abdominal transection of the spermatic cord and a modified open method in the standing horse for castration of descended testes in unilateral abdominal cryptorchids. STUDY DESIGN: Descriptive case series. METHODS: Fifteen unilateral abdominal cryptorchids were castrated laparoscopically by performing intra-abdominal ligation of both spermatic cords. The spermatic cord of the cryptorchid testis was not transected. After intra-abdominal transection of the spermatic cord of the descended testis, the testis was removed by an open castration technique in the standing horse. Data collected included time taken to perform the surgical procedure, surgical complications and post-operative recovery. RESULTS: Abdominal testes were located on the right side in eight horses and on the left in seven. The surgical procedure was easy to perform and few intra- or post-operative complications were seen. Pulse and respiration rates and rectal temperatures remained within normal limits during the evaluation period in all but one animal, which displayed transient pyrexia. The scrotal and laparoscopic incisional wounds healed well without any signs of swelling or exudate. In one Warmblood, there was prolapse of subcutaneous tissue the day after surgery, which retracted in 3 days. The owners were contacted by telephone at 2-3 months after discharge. Post-operative recovery had been uneventful in all horses. MAIN LIMITATIONS: This study included a small number of cases in which all surgeries were performed by or under the supervision of the same surgeon. Follow-up was limited to telephone reports from owners. CONCLUSIONS: A laparoscopic technique that is combined with an open scrotal incision to remove the descended testis in the standing horse was developed and shown to be a safe and reliable option for the castration of unilateral abdominal cryptorchids.

The role of quantitative electromyography (EMG) in horses suspected of acute and chronic grass sickness.

REASONS FOR PERFORMING THE STUDY: Clinical evidence of motor neuron involvement in equine grass sickness (EGS) has not been reported. HYPOTHESIS: Quantitative electromyography (EMG) analysis can elucidate subtle changes of the lower motor neuron system present in horses with EGS, performed ante mortem. METHODS: Fourteen horses diagnosed clinically with acute, subacute or chronic EGS were examined and quantitative EMG performed. Previously published data on healthy horses and horses with proven lower motor neuron disease (LMND) were used as controls. In 8 horses post mortem examination was performed, and in 7 muscle biopsies of the lateral vastus muscle underwent histopathology and morphometry. RESULTS: Clinical electrophysiological evidence of neuropathy was present in 12 horses. Analysis of data from the first 4 horses resulted in 95% confidence intervals (CI) of nontransformed data for motor unit action potential (MUP) duration in subclavian, triceps and lateral vastus muscle of 11.0-13.7, 14.8-20.3 and 12.2-17.2 msecs, respectively, and for MUP amplitude 291-453, 1026-1892 and 957-1736 microV, respectively. For number of phases the 95% CI was 3.6-4.4, 2.9-3.6 and 2.9-3.4, respectively, and for number of turns 5.0-6.5, 4.3-5.3 and 3.7-4.6, respectively. No changes in duration of insertional activity were measured. Pathological spontaneous activity was observed in all horses. EGS as evidenced by degenerative changes in the autonomic ganglia in combination with minor degenerative changes of the spinal lower motor neurons was observed on post mortem examination in all 8 available autopsies. In muscle biopsies of 4 out of 7 horses changes consistent with slight neurogenic atrophy were found. CONCLUSIONS AND POTENTIAL RELEVANCE: EMG results demonstrated the presence of a neuropathy of skeletal muscles in all horses suspected to have EGS. The combination of clinical and electrophysiological evidence may aid differential diagnosis of neurogenic disease in cases of weight loss and colic.

Study of cartilage and bone layers of the bearing surface of the equine metacarpophalangeal joint relative to different timescales of maturation.

REASONS FOR PERFORMING STUDY: A detailed and comprehensive insight into the normal maturation process of the different tissues that make up functional units of the locomotor system such as joints is necessary to understand the influence of early training on musculoskeletal tissues. OBJECTIVES: To study simultaneously the maturation process in the entire composite structure that makes up the bearing surface of a joint (cartilage, subchondral and trabecular bone) in terms of biochemical changes in the tissues of juvenile horses at 2 differently loaded sites of the metacarpophalangeal joint, compared to a group of mature horses. HYPOTHESIS: In all the structures described above developmental changes may follow a different timescale. METHODS: Age-related changes in biochemical characteristics of the collagen part of the extracellular matrix (hydroxylysine, hydroxyproline, hydroxypyridinum crosslinks) of articular cartilage and of the underlying subchondral and trabecular bone were determined in a group of juvenile horses (n = 13) (Group 1, age 6 months-4 years) and compared to a group of mature horses (n = 30) (Group 2, >4 years). In both bony layers, bone mineral density, ash content and levels of individual minerals were determined. RESULTS: In cartilage, subchondral bone and trabecular bone, virtually all collagen parameters in juvenile horses were already at a similar (stable) level as in mature horses. In both bony layers, bone mineral density, ash- and calcium content were also stable in the mature horses, but continued to increase in the juvenile group. For magnesium there was a decrease in the juvenile animals, followed by a steady state in the mature horses. CONCLUSIONS: In horses age 6 months-4 years, the collagen network of all 3 layers within the joint has already attained a mature biochemical composition, but the mineral composition of both subchondral and trabecular bone continues to develop until approximately age 4 years. POTENTIAL RELEVANCE: The disparity in maturation of the various extracellular matrix components of a joint can be assumed to have consequences for the capacity to sustain load and should hence be taken into account when training or racing young animals.

Gentamicin nephrotoxicity--a comparison of in vitro findings with in vivo experiments in equines.

The aminoglycoside gentamicin is often used in equine practice. Despite its clinical use, concerns remain regarding the potential toxic side-effects, such as nephrotoxicity, in equine patients, particularly after repeated dosing. The aim of the study was to investigate first in vitro the mechanisms contributing to the renal toxicity of gentamicin and to identify sensitive biomarkers indicating proximal tubule damage. To this end, the kidney-derived cell lines LLC-PKI and MDCK were treated with gentamicin at different concentrations. Toxicity was assessed by measuring the release of gamma-glutamyl transferase (GGT), and the production of reactive oxygen species (ROS). Cell viability was measured using Alamar blue (AB) and Neutral red (NR) cytotoxicity assays. Gentamicin exerted a dose-dependent toxicity. Primarily, loss of brush border membrane integrity, indicated by GGT leakage, and an increased ROS production were observed. As GGT was found to be a sensitive marker for gentamicin-induced renal cell injury, in the subsequent in vivo experiments, in which ponies were given gentamicin (3.0 mg/kg bw three times daily and 4.5 mg/kg bw twice daily) for five consecutive days, plasma levels and the urinary excretion of GGT and creatinine were measured and the GGT:creatinine ratio was calculated. Elevated GGT levels in urine following gentamicin therapy were observed, but this enzyme leakage was transient and returned to baseline values after cessation of therapy. It could thus be concluded that even a conservative dose regimen of gentamicin did not result in significant renal toxicity in healthy ponies.

Influence of fluid therapy on gentamicin pharmacokinetics in colic horses.

The aminoglycoside antibiotic gentamicin is commonly used in equine medicine for the prevention and treatment of Gram-negative and staphylococcal bacteria in surgically treated colic patients. The pharmacokinetics of gentamicin in these patients might be altered by the disease status, and/or under the influence of fluid therapy. The purpose of this study was to investigate the effect of intravenous fluid treatment on gentamicin kinetics in colic patients. Colic patients subjected to laparotomy were given fluid infusions according to clinical status. Following gentamicin administration, blood samples were taken for gentamicin analysis at different time points, and the main pharmacokinetic parameters including Vc, Vss, t(1/2) and MRT were calculated. Horses undergoing fluid therapy showed a significantly different t(1/2), clearance and MRT as compared to non-infused patients. However, taking into account the clinical status of the patients receiving fluid support, the data suggest that endotoxaemia, rather than fluid therapy, influence gentamicin pharmacokinetics following laparotomy.

Relationship between synovial fluid levels of glycosaminoglycans, hydroxyproline and general MMP activity and the presence and severity of articular cartilage change on the proximal articular surface of P1.

REASONS FOR PERFORMING STUDY: Osteoarthritis (OA) is one of the most prevalent and disabling chronic conditions affecting horses and leads to degeneration of articular cartilage. Diagnosis is based on clinical signs in combination with radiography, which is relatively insensitive and provides only an indication of accumulated damage. Alternative methods, such as molecular markers, are therefore needed that can quantitatively, reliably and sensitively detect osteoarthritic changes in the joints at an early stage of the disease. If such markers are to be used reliably, it is important to know the relationship between marker concentration and cartilage composition. OBJECTIVES: To study the relationship between cartilage composition, synovial fluid levels of glycosaminoglycans (GAGs), hydroxyproline (Hyp) and general matrix metalloproteinase (MMP) activity, and the presence and severity of articular cartilage damage on the articular surface of P1. METHODS: Synovial fluid (SF) was collected from the metacarpophalangeal joints of 60 mature horses, and levels of GAGs, Hyp and general MMP activity were determined. Further, GAG and denatured collagen content of the articular cartilage were determined at the dorsal articular margin of P1 (site 1) and central cavity (site 2). The presence and severity of cartilage change was quantified using the cartilage degeneration index (CDI), measured at the same 2 sites. Correlations between SF parameters, cartilage composition and degree of cartilage degeneration were sought using correlation analysis. RESULTS: There was no correlation between GAG or Hyp content of SF and the amount of GAGs or denatured collagen, respectively, in cartilage. In joints with moderate to severe cartilage damage, the GAG content of site 1 was significantly lower than in joints with no to minimal cartilage change (P = 0.005) and there was a negative correlation between the amount of denatured collagen and GAG content at site 1 in all joints (r = -039, P = 0.002). Further, in joints with moderate to severe cartilage damage, there was a significant positive correlation between MMP activity in SF and Hyp levels in SF (r = 0.72, P < 0.001) and CDI at sites 1 (r = 0.46, P = 0.03) and 2 (r = 0.43, P = 0.04). CONCLUSIONS: General MMP activity in joints with moderate to severe cartilage damage is related to the severity of those cartilage changes and to Hyp levels in SF. Glycosaminoglycan levels in SF are not directly related to MMP activity, GAG content of articular cartilage or severity of cartilage change. POTENTIAL RELEVANCE: Glycosaminoglycan levels in SF are not helpful for the early detection of cartilage lesions. In damaged joints, Hyp levels may give an indication of the severity of cartilage change as they are strongly related to MMP activity, but do not qualify as markers for the presence or absence of cartilage lesions.

[Inguinal herniation in foals. Literature review and a case report]. / Hernia inguinalis/scrotalis bij veulens. Een literatuuroverzicht en bespreking van een bijzondere casus.

A literature review is given concerning the occurrence, clinical signs and possible treatment of the different types of inguinal herniation in foals. A six-week old filly with a reducible inguinal hernia is described in detail.

[Priapism in the stallion]. / Priapismus bij de hengst.

A review of the literature is given concerning the anatomy and pathophysiology of the equine penis with regard to priapism: a prolonged erection of the penis not associated with sexual arousal. Several treatment options, such as flushing of the corpus cavernosum penis with heparinized saline and the creation of shunt between the corpus cavernosum penis and the corpus spongiosum penis are discussed. Subsequently, a case of priapism in a stallion following the injection of acepromazine, is discussed. The priapism resolved after the corpus cavernosum penis was flushed with the stallion under general anaesthesia.

The use of a polypropylene mesh for treatment of ruptured collateral ligaments of the equine metatarsophalangeal joint: a report of two cases.

The prognosis of ruptured collateral ligaments of the metacarpophalangeal or metatarsophalangeal joint in horses is usually considered to be poor, especially for future athletic performance. The main problem is the development, due to joint instability, of osteoarthritis, which may result in persistent lameness. In this paper a surgical technique is described in which joint stabilisation is realised by using a polypropylene mesh as a substitute for the ruptured ligaments, with the subsequent application of a cast for 7 weeks. The technique was successfully performed in 2 horses with ruptured lateral collateral ligaments of a metatarsophalangeal joint. Fifteen months after surgery both horses resumed exercise. Performance could be classified as fair in one case and good in the other. It is concluded that the preliminary results obtained with this surgical technique to stabilise ruptured collateral ligaments of the fetlock joint are promising.