Fracture of the medial intercondylar eminence of the tibia in horses treated by arthroscopic fragment removal (21 horses).

BACKGROUND: Fractures of the medial intercondylar eminence of the tibia (MICET) are scarcely reported in horses. OBJECTIVES: To report the clinical and diagnostic findings, surgical treatment and outcome in a series of horses presented with MICET fracture and treated with arthroscopic fragment removal. STUDY DESIGN: Multicentre retrospective case series. METHODS: Case records of horses diagnosed with MICET fractures that had undergone surgical treatment were reviewed. Follow-up information was obtained from re-examination visits and/or owners. RESULTS: Twenty-one cases were identified at 9 equine hospitals between 2004 and 2016. A history of trauma and acute onset of lameness was reported in 12 horses. All cases underwent fracture removal via arthroscopy of the medial femorotibial joint. The cranial cruciate ligament was intact in 6 horses and damaged in 15 horses (damage was ≤25% [n = 9], 25-50% [n = 4] or ≥50% [n = 2] of the cross-sectional area). The cranial ligament of the medial meniscus was damaged in 11 horses (≤25% [n = 8], 25-50% [n = 3]). The medial meniscus was damaged in 5 horses and articular cartilage damage was identified in 14 horses (mild [n = 8], moderate [n = 6]). Follow-up information (median 14 months; 4 months-6 years) was available for 20 cases; 2 horses were sound but convalescing; 13 horses were sound and returned to their previous or expected use. Of the 4 horses with the most severe changes to the articular soft tissue structures, 2 remained lame and 2 were subjected to euthanasia because of persistent lameness. MAIN LIMITATIONS: The retrospective, multicentre nature of this study and the limited number of horses are the main limitations. CONCLUSIONS: Fractures of the MICET are commonly associated with a traumatic event. Prompt diagnosis and early arthroscopic removal of the fracture are recommended.

Navigational ultrasound imaging: A novel imaging tool for aiding interventional therapies of equine musculoskeletal injuries.

REASONS FOR PERFORMING STUDY: Navigational ultrasound imaging, also known as fusion imaging, is a novel technology that allows real-time ultrasound imaging to be correlated with a previously acquired computed tomography (CT) or magnetic resonance imaging (MRI) study. It has been used in man to aid interventional therapies and has been shown to be valuable for sampling and assessing lesions diagnosed with MRI or CT that are equivocal on ultrasonography. To date, there are no reports of the use of this modality in veterinary medicine. OBJECTIVES: To assess whether navigational ultrasound imaging can be used to assist commonly performed interventional therapies for the treatment of equine musculoskeletal injuries diagnosed with MRI and determine the appropriateness of regional anatomical landmarks as registration sites. STUDY DESIGN: Retrospective, descriptive clinical study. METHODS: Horses with musculoskeletal injuries of the distal limb diagnosed with MRI scheduled for ultrasound-guided interventional therapies were evaluated (n = 17 horses with a total of 29 lesions). Anatomical landmarks used for image registration for the navigational procedure were documented. Accuracy of lesion location and success of the procedure were assessed subjectively and described using a grading scale. RESULTS: All procedures were accurately registered using regional anatomical landmarks and considered successful based on our criteria. Anatomical landmarks were described for each lesion type. The addition of navigational imaging was considered to greatly aid the procedures in 59% of cases and added information to the remainder of the procedures. The technique was considered to improve the precision of these interventional procedures. CONCLUSIONS: Navigational ultrasound imaging is a complementary imaging modality that can be used for the treatment of equine soft tissue musculoskeletal injuries diagnosed with MRI.

Validation of a photogrammetric technique for computing equine hoof volume.

Assessment of equine foot conformation is often based on linear and angular measurements performed on lateral digital photographs. However, quantification of external foot conformation requires more comprehensive assessments to capture the shape of the entire foot. Volumetric measurements of the hoof capsule represent a summary measure quantifying foot shape. The aim of this study was to develop a method for computation of virtual foot models from digital foot images allowing precise and accurate volumetric measurements. This photogrammetric technique was then assessed for the characterization of foot volume changes associated with foot trimming. Using the technique, three different photographers imaged feet from 18 cadavers at different time points and one analyst processed their images to generate virtual computer models. Volumetric measurements were obtained from these models to determine their precision in the context of 'Photographer', 'Time' and the effect of 'Trimming'. Computed tomographic (CT) imaging was used to assess the accuracy of the photogrammetric method. Pre-trim photogrammetric measurements showed excellent precision and accuracy and the results did not depend on the person acquiring the images. The accuracy of post-trim photogrammetric measurements deteriorated in comparison with the average differences measured by CT imaging (19 cm(3)). Precise volumetric measurements were obtained using the photogrammetric method, but average differences in foot volume after trimming as measured by CT imaging are likely too small to be detected with confidence.

Deep digital flexor tenotomy for treatment of severe laminitis in a cow.

A first-calf Guernsey cow was referred for evaluation of severe udder edema, mastitis, metritis, and ketosis. During the course of treatment, the cow became recumbent and was unable to rise. Intensive treatment resulted in the cow being able to stand for short periods with the aid of a sling. However, severe pressure necrosis of the udder and ongoing mastitis made performance of a complete mastectomy necessary. After surgery, the cow's condition improved, although assistance in standing was still required. Radiography of the distal phalanges revealed severe rotation in the right lateral and left medial digits of the hind limbs. The laminitis was nonresponsive to medical management; therefore, a deep digital flexor tenotomy was performed in the affected claws. The procedure provided almost immediate relief of signs of foot pain and resulted in ability to stand without assistance. Deep digital flexor tenotomy should be considered when treating cows with severe laminitis.

Risk factors for reduced postoperative fecal output in horses: 37 cases (1997-1998).

OBJECTIVE: To determine prevalence and risk factors for development of ileus of the large intestine after surgery in horses, identified by reduced postoperative fecal output (RPFO). DESIGN: Retrospective study. ANIMALS: 37 horses that developed RPFO after undergoing general anesthesia for reasons unrelated to the gastrointestinal tract. PROCEDURE: Fecal output was obtained from medical records as number of defecations per 24-hour period after surgery; RPFO was defined as < or = 3 defecations per 24-hour period after surgery. The reference population included 48 horses that defecated > or = 4 times during the same period. Demographic, clinical, and surgical variables were evaluated for their association with development of RPFO by use of logistic regression analysis. RESULTS: Ten (12%) horses, all of which had RPFO, developed signs of colic after surgery. Horses > or = 5 years old that underwent orthopedic procedures of > 60 minutes' duration and that did not receive phenylbutazone after surgery were at significant risk for developing RPFO. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that after surgery unrelated to the gastrointestinal tract in horses, there is an intermediate clinical phase characterized by reduced fecal output preceding overt signs of colic. Recognition of RPFO may reduce morbidity and mortality of such horses.

Ultrasonographic evaluation of tarsocrural joint cartilage in normal adult horses.

Ultrasonographic examination of the tarsus was performed on four clinically and radiographically normal limbs of adult horses. Particular attention was paid to the articular cartilage surfaces of the trochlear ridges of the talus and the distal intermediate ridge of the tibia. Two separate measurements of articular cartilage thickness were acquired from a longitudinal view at each site. Anatomy was confirmed with post mortem dissection. Ultrasonography was found to be a practical method for imaging the articular cartilage over the trochlear ridges of the talus and distal intermediate ridge of the tibia. The cartilage appeared as a hypoechoic band overlying the hyperechoic subchondral bone. The mean cartilage thickness over the lateral and medial trochlear ridges of the talus and the distal intermediate ridge of the tibia were 0.57 mm, 0.58 mm and 0.7 mm respectively. These measurements may have value for comparison to thickened cartilage and lesions of osteochondrosis and abnormally thinned cartilage of osteoarthritis. Ultrasound examination was not helpful in evaluating the proximal and distal intertarsal and tarsometatarsal joints, the close proximity of the articular surfaces obscured visualization of the articular cartilage.

Diagnosis and surgical treatment of periapical infection of the third mandibular molar in five horses.

Diagnosis and treatment of periapical infection of the third mandibular molar in 5 horses was assessed. In 4 of 5 horses, there was a recent history of dental work performed. Diagnosis required multiple imaging techniques. Radiography revealed evidence of periapical bone lysis or tooth root lysis of the third mandibular molar in 3 of 5 horses. Sonographic examination was effective in identifying abscesses within the masseter muscle and defects of the lateral cortex of the mandible in 4 of 5 horses. Nuclear scintigraphy was diagnostic in 1 of 2 horses examined. All horses were treated by repulsion of the affected tooth. The surgical approach involved elevating the masseter muscle from the caudal portion of the mandible. This approach provided excellent access to the affected tooth with minimal postoperative complications. All incisions healed with good cosmetic results.

Drug disposition and dosage determination of once daily administration of gentamicin sulfate in horses after abdominal surgery.

OBJECTIVE: To evaluate pharmacokinetics of once daily i.v. administration of gentamicin sulfate to adult horses that had abdominal surgery. DESIGN: Prospective study. ANIMALS: 28 adult horses that underwent abdominal surgery for colic. PROCEDURE: 14 horses were treated with each dosage of gentamicin (i.e., 6.6 or 4 mg/kg, i.v., q 24 h) and blood samples were collected for pharmacokinetic analysis. Plasma gentamicin concentrations were measured by use of a fluorescence polarization immunoassay. Pharmacokinetic analysis measured the elimination half-life, volume of distribution, and gentamicin total systemic clearance. Treatment outcome, CBC, and serum creatinine concentrations were recorded. RESULTS: 1 horse in the high-dosage group died. All other horses successfully recovered, and did not develop bacterial infection or have evidence of drug toxicosis resulting in renal injury. Mean pharmacokinetic variables for gentamicin administration at a high or low dosage (i.e., 6.6 or 4 mg/kg, i.v., q 24 h) were half-life of 1.47 and 1.61 hours, volume of distribution of 0.17 and 0.17 L/kg, and systemic clearance of 1.27 and 1.2 ml/kg/min, respectively. Mean serum creatinine concentration was 1.74 and 1.71 for the high and low dosages, respectively, and serum creatinine concentration was not correlated with gentamicin clearance. CONCLUSIONS AND CLINICAL RELEVANCE: Gentamicin administration at a dosage of 4 mg/kg, i.v., every 24 hours, will result in plasma concentrations that are adequate against susceptible bacteria with a minimum inhibitory concentration (MIC) of < or = 2.0 micrograms/ml. Gentamicin administration at a calculated dosage of 6.8 mg/kg, i.v., every 24 hours will result in optimum plasma concentrations against susceptible bacteria with a MIC of < or = 4.0 micrograms/ml.

Endoscopic treatment of suspected infectious intertubercular bursitis in a horse.

A 9-year-old gelding was evaluated because of a 30-day history of mild intermittent left forelimb lameness. The only detectable abnormality was mild atrophy of the musculature of the proximal portion of the left forelimb. The cause of the lameness could not be determined. The horse was discharged from the hospital, but was reexamined 6 weeks later because of worsening of the lameness. At that time, the horse resisted flexion and extension of the left shoulder joint, and results of evaluation of an ultrasound-guided aspirate of fluid from the intertubercular bursa were suggestive of infection. Endoscopic examination of the bicipital bursa revealed synovial hypertrophy, particularly in the distal aspect of the bursa. The bursa was lavaged, and a synovial resector was used to remove inflamed synovium. The horse recovered and was healthy 4 months later. In this horse, endoscopy allowed adequate examination of the intertubercular bursa and was not technically difficult.

Effects of chlorhexidine gluconate and chlorous acid-chlorine dioxide on equine fibroblasts and Staphylococcus aureus.

Equine fibroblasts and Staphylococcus aureus were exposed for 30 minutes to six dilutions of chlorhexidine gluconate, a chlorous acid-chlorine dioxide irrigation solution, a chlorous acid-chlorine dioxide disinfectant, and phosphate buffered saline controls. Cell viability was determined by trypsinizing the cells, staining them with trypan blue, and counting cells that did not take the stain. All fibroblasts were killed when exposed to 1.0% and 0.5% chlorhexidine. The survival rate of fibroblasts increased linearly with decreasing concentrations of chlorhexidine gluconate, with a peak survival of 50% at 0.005% chlorhexidine. The chlorous acid-chlorine dioxide irrigation solution was the least toxic to fibroblasts, with survival rates equivalent to those of controls. The chlorous acid-chlorine dioxide disinfectant was 100% cytotoxic even when diluted 1:1 with phosphate buffered saline. S. aureus growth was inhibited by 1.0% and 0.5% chlorhexidine gluconate; concentrations of 0.05%, 0.01%, and 0.005% did not differ from sterile water controls. The chlorous acid-chlorine dioxide irrigation solution did not inhibit growth of S. aureus in brain-heart infusion broth. The chlorous acid-chlorine dioxide disinfectant inhibited growth of S. aureus.