Comparison of radiography and ultrasonography for the diagnosis of osteochondritis dissecans in the equine femoropatellar joint.

REASONS FOR PERFORMING STUDY: Osteochondritis dissecans (OCD) lesions of the femoropatellar (FP) joint are diagnosed routinely by radiography, but lesions located in the trochlear groove or without accompanying subchondral bone changes can be difficult to visualise. Ultrasonography allows evaluation of articular cartilage and subchondral bone in the FPjoint. OBJECTIVES: To document the radiographic and ultrasonographic appearance of OCD lesions in the equine FP joint, grade ultrasonographic lesions and compare their accuracy in the diagnosis of these lesions. METHODS: The medical records of all horses diagnosed with FP OCD between 1995 and 2006 were assessed. Inclusion criteria included availability of both radiographic and ultrasonographic images. Lesion characteristics were evaluated in each trochlear ridge and trochlear groove. For assessment of the accuracy (sensitivity and specificity) of both imaging techniques in the diagnosis of OCD, only cases with an arthroscopic or necropsy examination were studied. RESULTS: Twenty-one horses were included. OCD lesions were diagnosed by radiography (30/32 joints) and ultrasound (32/32 joints). The lateral trochlear ridge (LTR, 91%) and the medial trochlear ridge (MTR, 17%) were involved on radiography. The localisation on ultrasound examination was similar (97% LTR, 25% MTR). All but one lesion seen on radiography were also detected with ultrasound; 2 LTR and 3 MTR lesions, not seen on radiography were diagnosed by ultrasound and confirmed at arthroscopy or necropsy. The specificity was 100% regardless of the site and imaging procedure except for the distal third of the MTR (94% for ultrasound). The sensitivity varied, depending on lesion site. CONCLUSION: Ultrasonography is a valuable diagnostic tool to diagnose OCD lesions in the FP joint and more sensitive than radiography for lesions affecting the MTR of the distal femur. CLINICAL RELEVANCE: Ultrasound should be considered as a useful adjunct to radiography for diagnosing equine FP OCD, especially in cases of high clinical suspicion but equivocal radiographic findings. Images can be generated immediately when digital radiography is not available, permitting an immediate on-site diagnosis.

Ultrasound-guided periarticular injections of the sacroiliac region in horses: a cadaveric study.

REASON FOR PERFORMING STUDY: The traditional techniques for injection of the sacroiliac (SI) region are based on external landmarks. Because of the depth of the SI joint and pathological modifications, SI injections are sometimes challenging in horses. HYPOTHESIS: An ultrasound-guided techniques would allow placement of the needle without depending on external landmarks. METHODS: Fourteen pelvic specimens were isolated from mature horses. A 20 cm bent spinal needle was positioned with ultrasonographic guidance under both iliac wings aiming for SI joints using 5 approaches: cranial, craniomedial, medial and 2 caudal approaches. The length of needle inserted was recorded and 2 ml of latex injected. The distance from latex to the closest sacral articular margin, the contact between latex and the SI interosseous ligament or the contact with the neurovascular structures emerging from the greater sciatic foramen were recorded at the time of dissection. RESULTS: Latex was identified under the iliac wing in all injections but one. The distance from the latex to the closest sacral articular margin was significantly shorter (P = 0.02) for the 2 caudal approaches compared to the cranial, craniomedial and medial approaches. Contact between latex and the SI interosseous ligament was significantly more frequent (P = 0.01) with the cranial, craniomedial and medial approaches (38/73) compared to the caudal approaches (1/24). Contact between latex and the neurovascular structures was significantly less frequent (P = 0.005) for the cranial and craniomedial approaches (0/47) compared to the medial and caudal approaches (8/60). Four erratic injections were encountered. CONCLUSIONS: Ultrasonographic guidance allowed the needle to engage under the iliac wing without being dependent on external landmarks. The caudal approaches allowed deposition of liquid extremely close to the SI joint although retroperitoneal injections occurred. CLINICAL RELEVANCE: Each approach has advantages/drawbacks that could be favoured for selected purposes, but additional work is required to evaluate them on clinical cases.

Excessive degradation of type II collagen in articular cartilage in equine osteochondrosis.

Articular osteochondrosis (OCD) occurs in both man and animals. The etiology remains to be determined. Studies of OCD lesions in animals may provide clues as to its pathogenesis. The aim of our study was to determine whether there was evidence for increased degradation namely proteoglycan (PG) release and type II collagen cleavage in articular cartilage harvested from OCD lesions. We examined ex vivo explants at post-mortem from equine OCD lesions and macroscopically normal site and age matched cartilage. These were cultured over a 10 day period in serum-free medium. Type II collagen cleavage was measured in articular cartilage and media using an Elisa assay to detect the COL2-3/4C(short) epitope, which is generated on cleavage of the triple helix of type II collagen by collagenases. PG release was measured by a dye-binding assay. Cumulative release of PG and COL2-3/4C(short) and their contents in cartilage at the end of the culture period were determined. In OCD lesions there was a significant increase in type II collagen cleavage by collagenase but no evidence for increase of PG degradation. These findings point to a selective increase in type II collagen cleavage by collagenases, in OCD lesions of the kind observed in osteoarthritis. Further work is needed to determine whether changes represent primary or secondary events in the pathogenesis of OCD.

Variations in urinary gamma glutamyl transferase/urinary creatinine ratio in horses with or without pleuropneumonia treated with gentamicin.

The urinary GGT/urinary creatinine (uGGT/uCR) ratio was measured on Days 1, 3 and 10 in 4 adult, healthy horses; in 6 adult, healthy horses treated with gentamicin at recommended dosages and 9 adult horses treated for pleuropneumonia with gentamicin at recommended dosages. Plasma creatinine and gentamicin trough concentrations were measured on the same days. The uGGT/uCr ratio was higher in the normal horses (mean +/- s.d. 22.85 +/- 13.69) than previously reported normal values (10.5 +/- 6.8) (Adams and McClure 1985). Analysis of variance for repeated measures was used to compare the ratio in the 3 groups while controlling for the effect of time. Sick horses had a significantly higher uGGT/uCr ratio than either of the 2 groups of normal horses. Both groups of horses that were treated with gentamicin had similar percentage increases in uGGT/uCr ratio over the treatment period with the most marked increases found between treatment Days 1 and 3. The increase in uGGT/Cr ratio was predominantly a result of an increase in uGGT activity rather than a decrease in uCr concentration. The increase in uGGT activity and uGGT/uCr ratio occurred without abnormalities in serum creatinine or gentamicin trough concentrations. These findings demonstrate that urine GGT activity and uGGT/uCr ratio should be expected to increase in response to gentamicin therapy at recommended dosages without measurable changes in serum creatinine. This suggests that an elevation of the uGGT/uCr ratio in horses being treated with gentamicin would not necessarily require changes in, or withdrawal of, the gentamicin treatment as long as increases in the plasma creatinine do not exceed 0.3 g/l and gentamicin trough concentrations are < 2 micrograms/l.

Effect of prior lavage on bronchoalveolar lavage fluid cell population of lavaged and unlavaged lung segments in horses.

Bronchoalveolar lavage (BAL) was performed on 16 horses to determine whether it caused local or diffuse inflammation in the lungs. In 7 horses, BAL was performed in both lungs twice, 48 hours apart. Although total cell counts of the BAL samples did not change significantly, there were increased numbers and percentage of neutrophils in the second lavage fluid samples. In 5 horses, BAL was performed in 1 lung and repeated 48 hours later in the same lung and in the corresponding airway in the contralateral lung. The absolute cell count and percentage of neutrophils were significantly (P = < 0.05) increased in the second sample from the lung that was lavaged twice. In 4 horses, BAL was performed in 1 lung and 48 hours later, repeated in an adjacent airway to the first BAL site, and in the corresponding airway in the contralateral lung. Significant differences were not detected in the total or differential cell counts of the BAL fluid recovered at any time, except for an increase in neutrophil percentage in the second sample in the contralateral lung. The increased neutrophil percentage values were within the range of normal for healthy horses. Results of the study suggested that, in horses, BAL induces a localized pulmonary neutrophil influx that persists at least 48 hours and is characterized by a relative and absolute increase in the number of neutrophils in the lavage fluids. and has been shown to be a safe technique with cytologic results that correlate well with histopathologic lesions in horses. Subsequently the technique has been used to collect large numbers of pulmonary cells for study.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of lung site and fluid volume on results of bronchoalveolar lavage fluid analysis in horses.

Bronchoalveolar lavage (BAL) fluid was analyzed in healthy horses, using different lavage fluid volumes and lung sites. The only significant difference in the cellular composition of BAL fluid between the right and left lungs was the mast cell numbers, which were significantly higher in the left lung. Total cell count ranged from 34 to 330 cells/microliter for the right lung and 43 to 330 cells/microliter for the left lung. Percentage of neutrophils ranged from 1 to 7% in the right lung and 1 to 5% in the left lung. The small-volume (50 ml) lavage had a greater percentage of neutrophils and a lesser percentage of mast cells in the large-volume (350 ml) lavage. Statistical difference in the composition of BAL fluid recovered was not detected between the 3 sequential 100-ml lavages and a single 300-ml lavage, except that macrophages were significantly higher in the 3 sequential 100-ml lavages. Values for BAL fluid analysis in healthy horses have varied considerably and this variation is from a failure to adhere to any standard technique for volume of fluid infused.

Bronchoalveolar lavage fluid cytologic findings in horses with pneumonia or pleuropneumonia.

Bronchoalveolar lavage was performed in 22 horses with pneumonia or pleuropneumonia. All horses had clinical evidence of pneumonia or pleuropneumonia on the basis of physical, radiographic, ultrasonographic, tracheobronchial aspirate or post-mortem findings. Results of lavage fluid analysis were normal in 9 horses, equivocal in 3 horses, and abnormal in 10 horses. Abnormal lavage fluid had increased total cell count, increased relative and absolute neutrophil counts, degenerative neutrophils, and decreased relative and absolute macrophage and lymphocyte counts.

Disposition of gentamicin administered intravenously to horses with sepsis.

Plasma concentration of gentamicin was measured 1, 4, and 6 hours after IV administration in 35 hospitalized adult horses on days 1, 3, 5, and 10 of treatment. The mean apparent elimination rate constant beta was 0.53 +/- 0.10 h-1 on day 1 for horses with normal plasma creatinine concentration and 0.41 +/- 0.13 h-1 for horses with abnormally high plasma creatinine concentration. There was no significant difference between beta of the hospitalized horses and of 6 healthy horses treated with gentamicin, but total clearance for the hospitalized horses with normal plasma creatinine concentration was significantly greater than that of the healthy horses and the hospitalized horses with abnormally high plasma creatinine concentration. Gentamicin clearance was significantly correlated with plasma creatinine concentration for healthy horses and hospitalized horses, and beta was significantly correlated with plasma creatinine concentration for hospitalized horses. Twelve of the 35 hospitalized horses required an adjustment in gentamicin dosage. Ten required a reduction, 1 an increase, and 1 a change in dosage and interval with no net change in total daily dose. One horse of 35 (2.9%) developed signs compatible with nephrotoxicosis on day 14 of treatment, despite appropriate gentamicin concentrations on day 10.

Pleuroscopic diagnosis of disseminated hemangiosarcoma in a horse.

A 7-year-old Thoroughbred mare was examined because of persistent bilateral epistaxis and respiratory distress. Evidence of bilateral pleural effusion was found during physical examination, and a large amount of serosanguineous fluid was drained from the right side of the thorax. Cytologic examination and bacteriologic culture of the transtracheal aspirate and pleural fluid did not yield evidence of sepsis. A coagulation profile was unremarkable. Radiographic and echographic changes were seen in the lung parenchyma. Pleuroscopy, with the horse standing, revealed numerous dark nodules on the pleura, diaphragm, and lung surface. On the basis of biopsy and necropsy findings, the histopathologic diagnosis was disseminated hemangiosarcoma.