INTRAARTERIAL INJECTION OF IODINATED CONTRAST MEDIUM FOR CONTRAST ENHANCED COMPUTED TOMOGRAPHY OF THE EQUINE HEAD

Minimizing the volume of contrast administered for contrast‐enhanced computed tomography (CT) of the equine head is desirable for reducing costs and risks of adverse reactions, however evidence‐based studies on the effects of varying volumes on image quality are currently lacking. The objective of the current study was to determine whether low‐volume intraarterial administration of contrast medium would result in an equivalent image quality and tissue attenuation vs. high‐volume intravenous bolus administration. A prospective cross‐over experimental design was used in a sample of six horses. After anesthetic induction, the right carotid artery was exposed surgically and catheterized. Four CT scans of the cranium were performed for each horse: baseline, immediately following intraarterial contrast injection, five‐min postinjection (return to baseline) and a final scan after intravenous contrast administration. Soft tissue attenuation in predetermined regions of interest (ROI); and length, width, and height measurements of the pituitary gland were recorded at each time point. Horses were euthanized and measurements of the pituitary gland were repeated postmortem. No adverse reactions to contrast administration were observed. Intraarterial and intravenous administration of contrast medium resulted in significantly greater soft tissue enhancement of some brain ROI's and the pituitary gland vs. baseline values. Pituitary gland measurements made on postcontrast CT images did not differ from those obtained during postmortem examination. Findings indicated that low‐dose intraarterial administration of contrast material in the equine head resulted in comparable soft tissue enhancement vs. high volume intravenous administration.     

Reliability of ultrasonography compared to radiography in revealing intestinal sand accumulations in horses

In order to investigate the reliability of ultrasonography in revealing intestinal sand accumulations, the cranioventral parts of the abdomen of 32 horses (age 3-20 years) with signs suggestive of gastrointestinal sand were examined radiographically and ultrasonographically. The amount of sand and its localisation, relative to the ventral abdominal wall, were evaluated radiographically and graded (scale 0-4). Motility of the intestine and whether it was lying against the ventral abdominal wall were evaluated ultrasonographically and the findings summed and graded (scale 0-3) to express the likelihood of the presence of sand. The ultrasonographic and radiographic grades were significantly associated. Out of 14 horses with a moderate or large ventral sand accumulation radiographically, 13 (92.9%) had a positive sand finding ultrasonographically. Out of 8 horses with no signs of sand radiographically, 7 were considered negative for sand ultrasonographically. The specificity of ultrasonography in detecting sand accumulations was 87.5% (7/8) and the sensitivity 87.5% (21/24). Small and more dorsally located accumulations were more difficult to detect ultrasonographically. Of the horses with a small or moderate amount of sand relatively ventrally or only a small part of sand close to the ventral abdominal wall, 70% (7/10) were considered suggestive or positive for sand ultrasonographically. The ventral aspect of sand accumulations was hyperechoic, causing varying acoustic shadowing and the intestine had decreased or absent motility. Ultrasonography revealed the length of the accumulations but gave very limited information of their height. Ultrasonography is a practical and reliable method for detecting sand accumulations but it cannot replace radiography.     

Antimicrobial disposition in pulmonary epithelial lining fluid of horses, part II. Doxycycline

Doxycycline concentrations, following two types of oral administration to horses, in pulmonary epithelial lining fluid (PELF) were examined and compared to plasma concentrations. The oral bioavailability was estimated from plasma concentrations achieved after an intravenous study in two horses. Doxycycline (10 mg/kg) was administered either intragastric or as topdressing to nonfasted horses. Blood samples were collected for drug analysis, before and 11 times after administration during 24 h. PELF samples were collected by a tampon device four times after drug administration and analysed for doxycycline concentrations. Another two horses received doxycycline intravenously at a dose of 3 mg/kg and plasma was taken 14 times during a 24- h period. The oral bioavailability of doxycycline was calculated to 17% after intragastric administration and 6% after topdressing administration in nonfasted horses. The degree of penetration of doxycycline into PELF, as described by AUC(PELF) /AUC(plasma) ratios, was 0.87 after intragastric administration. The results indicate that clinically relevant doxycycline concentrations are possible to maintain in PELF after intragastric administration. Furthermore, if bioavailability could be enhanced for per os administration, doxycycline might be a valuable drug for the treatment of lower airway infections in horses.     

Pharmacokinetics and pharmacodynamics of pantoprazole in clinically normal neonatal foals

REASONS FOR PERFORMING STUDY: Proton pump inhibitors (PPIs) are a mainstay of treatment for acid-related ulceration in man and horses. Currently, only an oral preparation of omeprazole is approved for use in horses in the USA. Intravenous administration of a PPI would provide a useful therapeutic alternative for those foals in which oral medication is not feasible. OBJECTIVE: To investigate the pharmacokinetics and pharmacodynamics of pantoprazole following i.v. or intragastric administration in healthy neonatal foals. METHODS: Seven healthy foals age 6-12 days at the start of the study were evaluated. Treatments included no drug administration, i.v. pantoprazole (1.5 mg/kg bwt) and intragastric pantoprazole (1.5 mg/kg bwt). Intragastric pH was recorded for 24 h after drug administration for pharmacodynamic evaluation. Plasma pantoprazole concentrations were measured using high-performance liquid chromatography. RESULTS: Plasma concentrations of pantoprazole were detectable at the 5 min sampling point following i.v. or intragastric administration. Bioavailability of intragastric-administered pantoprazole was 41%. Baseline mean hourly pH was 1.5-6.1. There was a statistically significant increase in mean hourly pH relative to untreated foals 2-24 h after i.v. or intragastric pantoprazole administration. CONCLUSIONS: Based on these data, i.v. or intragastric administration of pantoprazole results in a significant, prolonged increase in intragastric pH. POTENTIAL RELEVANCE: The i.v. formulation of pantoprazole may provide a clinically useful alternative means of acid suppression in foals unable to tolerate enteral administration of a PPI, such as those with pyloric outflow obstruction.     

EFFECT OF PERINEURAL ANESTHESIA ON THE ULTRASONOGRAPHIC APPEARANCE OF EQUINE PALMAR METACARPAL STRUCTURES

The purpose of this study was to describe ultrasonographic changes of the equine palmar metacarpal area attributed to the infiltration of local anesthetic solution and to determine whether these changes were noted immediately or at 24 h. The palmar metacarpal region of one forelimb in each of six horses was examined ultrasonographically with a 10-MHz linear array transducer and a 7.5-MHz curvilinear transducer. Transverse and longitudinal images were recorded at 5-cm intervals distal to the accessory carpal bone. High and low palmar and palmar metacarpal nerve blocks were performed with a 2% mepivacaine hydrochloride solution. Ultrasonographic examinations similar to the initial examination then were performed immediately, 1 h and 24 h postinjection. Cross-sectional area and mean pixel value were determined for the superficial and deep digital flexor tendons, the accessory ligament of the deep digital flexor tendon, the suspensory ligament, and the suspensory branches at each level and time period. Subjective ultrasonographic changes also were noted. No significant difference was noted in the cross-sectional area or mean pixel value of any structure at any level or time period compared to baseline. Subjective changes in the tendons and ligaments were not noted. There was mild hypoechoic swelling of the surrounding soft tissues and gas in the region of the injections. Gas could interfere with the evaluation of the origin of the suspensory ligament and the proximal portion of the accessory ligament of the deep digital flexor tendon within the first hour but was not detectable ultrasonographically at 24 h. Based on these findings, if gas interferes with an ultrasonographic examination performed temporally close to perineural anesthesia, a repeat examination at 24 h is recommended.     

Furosemide administration onehour before bone scintigraphy examination in horses does not improve the image quality or reduce the radiation dose rate

This prospective, cross‐sectional, pilot study aimed to investigate the effects of furosemide as a diuretic on the image quality of bone scintigraphy performed using ^99mTc‐HDP and to investigate the impact of furosemide on the radiation dose rate. Thirty‐one horses undergoing bone scintigraphy were included. The horses were divided into the control (n = 14) and furosemide group (n = 17), which received 1 mg/kg furosemide intravenously 1 h post ^99mTc‐HDP administration. The image quality was assessed subjectively and semi‐quantitatively. The bone‐to‐soft tissue (B:S) ratio was calculated from the counts per pixel of regions of interest (ROI) positioned over the left radial diaphysis (bone ROI) and its caudal soft tissue area (soft tissue ROI). The radiation rate dose (μSv/h) of both groups was measured at 0, 3, 6, 12, 18, and 24 h post ^99mTc‐HDP administration at a distance of 0, 30, and 100 cm from the head, kidney, and pelvis. The results showed no significant differences in the B:S ratio or the radiation dose rate observed between the groups. However, the radiation dose rate decreased by 56% at 3 h post ^99mTc‐HDP administration and keeping a distance of 30 cm reduced the radiation dose rate by 65%. Administering furosemide does not improve the image quality or reduce the radiation dose rate. The authors recommend commencing with bone scintigraphy 3 h post ^99mTc‐HDP administration and keeping at least a distance of 30 cm from the horse to reduce the staff radiation dose.     

RADIOGRAPHIC ANATOMY AND BARIUM SULFATE CONTRAST TRANSIT TIME OF THE GASTROINTESTINAL TRACT OF BEARDED DRAGONS (Pogona vitticeps)

The positive contrast gastrointestinal study is a common non‐invasive diagnostic technique that does not require anesthesia and enables good visualization of the digestive tract. Radiographic anatomy and reference intervals for gastrointestinal contrast transit time in inland bearded dragons (Pogona vitticeps) were established using seven animals administered 15 ml/kg of a 35% w/v suspension of barium by esophageal gavage. Dorso‐ventral and lateral radiographic views were performed at 0, 15, 30 min, 1, 2, 4, 6, 8, 12 h, and then every 12 h up to 96 h after barium administration. Gastric emptying was complete at a median time of 10 h (range 4–24 h). Median jejunum and small intestinal emptying times were 1 h (range 30 min–2 h) and 29 h (range 24–48 h), respectively. Median transit time for cecum was 10 h (range 8–12 h). Median time for contrast to reach the colon was 31 h (range 12–72 h) after administration. Results were compared to those obtained in other reptilian species. This technique appeared safe in fasted bearded dragons and would be clinically applicable in other lizard species.     

Association between cribbing and entrapment of the small intestine in the epiploic foramen in horses: 68 cases (1991-2002)

OBJECTIVE: To determine whether there was an association between a history of cribbing and epiploic foramen entrapment (EFE) of the small intestine in horses. DESIGN: Retrospective study. ANIMALS: 68 horses examined at the University of Illinois or the University of Liverpool veterinary teaching hospitals. PROCEDURE: For horses examined at the University of Illinois that underwent surgery because of strangulating small intestine lesions, information about cribbing was obtained through telephone calls with owners. For horses examined at the University of Liverpool that underwent surgery for colic for any reason, information about cribbing was obtained through a preoperative questionnaire. RESULTS: 13 of 19 (68%) horses with EFE examined at the University of Illinois had a history of cribbing, compared with only 2 of 34 (6%) horses with other strangulating small intestine lesions (odds ratio, 34.7; 95% confidence interval, 6.2 to 194.6). Similarly, 24 of 49 (49%) horses with EFE examined at the University of Liverpool had a history of cribbing, compared with 72 of 687 (10.5%) horses with colic caused by other lesions (odds ratio, 8.2; 95% confidence interval, 4.5 to 15.1). CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that there may be an association between cribbing and EFE in horses, with horses with a history of cribbing more likely to have EFE than horses without such a history.     

Radiographic anatomy and barium sulfate contrast study of the gastrointestinal tract of eastern box turtles (Terrapene carolina carolina)

Gastrointestinal disorders are an important cause of morbidity in box turtles (Terrapene carolina Carolina), however published information is currently lacking on the normal radiographic anatomy, transit, and emptying times of the gastrointestinal tract. A total of 15 healthy box turtles were recruited for this prospective, anatomic, reference interval study. Three‐view radiographic series (vertical beam dorsoventral, horizontal beam latero‐lateral, and horizontal beam rostrocaudal views) were acquired prior to contrast administration, and following contrast administration at 0, 20, 40, 60, and 90 min, 2, 4, 8, 12, and 24 h post administration, and every 24 h thereafter until all contrast was eliminated (15 mL/kg barium sulfate diluted to 30% weight per volume was administered via orogastric gavage). Vertical beam dorsoventral and horizontal beam latero‐lateral views were of excellent quality to identify gastrointestinal structures. The horizontal beam rostrocaudal view immediately postcontrast administration provided gastric and pyloric identification but had lesser diagnostic use at later time points due to anatomical superimposition. The gastrointestinal tract was composed of a tubular stomach, a pyloric sphincter near midline, a duodenum with a cranial flexure in the right cranial coelomic cavity, small intestines within the right coelom, a small cecal bulb, and a transverse and descending colon. Contrast media entered the large intestine by 24 h in all turtles, and a pyloro‐colic indentation was noted at the proximal descending colon. The large intestinal emptying was highly variable due to the interindividual variability of contrast sequestration within the cecal bulb. Findings from the current study serve as a reference on the gastrointestinal anatomy, transit, and emptying times in healthy eastern box turtles; and introduce a novel, horizontal beam, rostrocaudal view for gastrointestinal contrast studies in chelonians.     

Effect of GastroGard and three compounded oral omeprazole preparations on 24 h intragastric pH in gastrically cannulated mature horses

REASONS FOR PERFORMING STUDY: Ulceration of the squamous gastric mucosa is commonly associated with intensive training programmes in horses, but only one compound ('Gastrogard') has been subjected to controlled scrutiny as to therapeutic efficacy. OBJECTIVES: To compare the gastric acid inhibitory efficacy of one manufactured ('GastroGard') and 3 generic pharmacy-compounded preparations of the proton pump inhibitor omeprazole (OME) in the mature horse. HYPOTHESIS: All OME preparations tested would induce a clinically acceptable effect. METHODS: Six healthy mature gastrically cannulated horses of various breeds, 3 mares and 3 geldings, were used. Each product was administered per os once daily (0730 h) at an equivalent dose of 4 mg OME/kg bwt, in a randomised complete repeated measures design for sequence of individual preparation treatment per horse. There was a minimum of 14 days between treatment regimens. A portable unit that recorded pH continuously was attached to a recording electrode fixed within the gastric lumen via the gastric cannula. Three 24 h recordings were made one day before and during Days 2 and 7 after commencement of a 7 day treatment with each of the 4 individual preparations. The horses were fed as usual throughout the study. RESULTS: Only the GastroGard and one other preparation induced a significant increase over baseline in mean percentage of time that the pH was > 4.0 and mean median intragastric pH, during the first 14 and 12 h post treatment respectively, for both Days 2 and 7 post treatment. Both these products had a vehicle pH > 8.0, in contrast to the 2 less effective products, where the vehicle pH was < 6.0. CONCLUSIONS: OME at 4 mg/kg per os s.i.d. can effectively maintain intragastric pH at an accepted anti-ulcerogenic level for at least 12 h post administration in mature horses. In contrast to GastroGard, it should not be expected that all compounded preparations of OME are equally effective in achieving this performance. It appears that vehicle pH might play an important part in determining preparation efficacy. POTENTIAL RELEVANCE: Optimal timing for daily dosing of athletic horses with an effective OME preparation, in order to suppress gastric squamous ulceration, might be 4-8 h prior to a training session.     

Pharmacokinetics and bioavailability of theophylline in horses

The pharmacokinetics and bioavailability of theophylline in horses were investigated following both intravenous and intragastric administration of aminophylline solutions at doses corresponding to 15 and 10 mg/kg theophylline base. A rapid distributive phase with a half-life of approximately 15-30 min was followed by a slower elimination half-life averaging 15-17 h. The apparent volume of distribution averaged 850-900 ml/kg. Theophylline, administered as aminophylline solution, was both rapidly and completely absorbed from the equine digestive tract. Based on the bioavailability and disposition kinetics of theophylline, an intragastric dosage regimen for aminophylline consisting of the administration of 5 mg/kg at 12 h intervals would be expected to maintain plasma theophylline concentrations within the therapeutic range.     

Small intestinal segmental volvulus in horses after gastroscopy: Four cases (2011–2012)

Gastroscopy is the most common technique used in veterinary medicine to evaluate the stomach in horses and to date, no complications have been described associated with the procedure. This paper reports 4 cases developing a nonstrangulating segmental volvulus of the small intestine after gastroscopy at 3 referral institutions over a 2 year period. After performing diagnostic gastroscopy, all horses developed acute and severe clinical signs of colic unresponsive to medical management. Time range between gastroscopy and onset of colic signs varied from 10 min to 3 h. An exploratory laparotomy revealed a nonstrangulating segmental volvulus of the small intestine that was manually corrected without need for resection in all horses. In all cases, affected small intestine was severely gas distended. Three of those horses survived to discharge and were alive at follow‐up. One horse was subjected to euthanasia 2 days after surgery due to diffuse intestinal lymphoma.     

Effects of mosapride, a 5-hydroxytryptamine 4 receptor agonist, on electrical activity of the small intestine and cecum in horses

OBJECTIVE: To examine the effects of various doses of mosapride, a 5-hydroxytryptamine 4 receptor agonist, on motility of the small intestine and cecum in horses by use of electrical activity and to determine the dose that provides the optimal response. ANIMAL: 6 healthy adult Thoroughbreds. PROCEDURE: Electrical activity of the small intestine and cecum was recorded before and after mosapride administration by use of an electrogastrograph. Mosapride (0.5, 1, 1.5, and 2 mg/kg) was dissolved in 200 mL of water and administered orally to horses through a nasogastric tube. Three hours after drug administration, mean amplitude of electrical activity calculated for a period of 30 minutes was expressed as the percentage of the mean amplitude of electrical activity for a period of 30 minutes before drug administration. RESULTS: Mosapride administered orally increased the percentage of the mean amplitude of electrical activity in the small intestine and cecum in a dose-dependent manner. Mean +/- SD values differed significantly for 1, 1.5, and 2 mg/kg (127.0 +/- 12.5%, 137.7 +/- 22.2%, and 151.1 +/- 24.0%, respectively) in the small intestine and for 1.5 and 2 mg/kg (130.1 +/- 34.5% and 151.6 +/- 45.2%, respectively) in the cecum. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis of results of this study clearly documents that mosapride promotes motility in the small intestine and cecum of horses and that the optimal orally administered dosage is 1.5 to 2 mg/kg. Therefore, mosapride may be useful for treatment of horses with gastrointestinal tract dysfunction.     

PILOT STUDY TO ASSESS MEAL PROGRESSION THROUGH THE GASTROINTESTINAL TRACT OF HABITUATED DOGS DETERMINED BY FLUOROSCOPIC IMAGING WITHOUT SEDATION OR PHYSICAL RESTRAINT

A limiting factor of radiographic contrast studies is the requirement for restraint of the animal in order to reduce movement artifacts. To demonstrate that gastrointestinal transit can be analyzed by a barium meal in nonsedated and unrestrained dogs, a pilot study of six adult Labrador retriever dogs was undertaken. Study subjects were selected by convenience sampling from an available population of Labrador dogs and were trained to stand motionless during radiographic fluoroscopy. Following a meal containing 7% w/w powdered barium sulfate, radiographic images were generated using a digital fluoroscope C‐arm, at intervals of 5, 15, and 30 min, and at 1, 2, 3, 4, 5, 6, 7, and 8 h. A qualitative assessment of fill density using a 5‐point scale was made for the stomach, small intestine, and ascending, transverse, and descending regions of the colon at each timepoint. Gastric emptying half‐time occurred between 1 and 2 h postmeal. Mean fill density of the small intestine increased from 15 min postmeal and reached a peak at 3 h postmeal. Mean fill density of the proximal large intestine mirrored that of the small intestine. The distal large intestine remained empty for the first 2 h postmeal, then increased between hours 2 and 5 postmeal, and was subsequently at maximum fill density from hour 6 postmeal onwards. Fluoroscopic observation of a barium contrast meal provided an effective indication of the amount and progression of ingested food through the various regions of the gastrointestinal tract in habituated, fully conscious dogs.     

Diseases of the liver

The ability to image the liver in horses can add valuable diagnostic information or aid in guided biopsy procedures. Anytime the size, shape, position, and texture of the liver can be determined, additional information about the horse's condition is gained. Conditions such as cholelithiasis, neoplasia, fibrosis can be detected ultrasonographically.     

DIAGNOSTIC SENSITIVITY OF BONE SCINTIGRAPHY FOR EQUINE STIFLE DISORDERS

Disorders of the stifle are a common cause of lameness in horses yet the accuracy of scintigraphy for diagnosis of stifle conditions is controversial. The aim of retrospective cross‐sectional study was to determine the diagnostic sensitivity (Se) of bone scintigraphy in detecting stifle disease and to determine if two orthogonal scintigraphic images improve diagnostic Se. Horses that underwent scintigraphic examination during a two‐year period were included. Horses were divided into two groups: group 1 (N = 23) had lameness that was localized to the stifle by intra‐articular analgesia and group 2 (N = 182) had lameness that was localized to a different location. Scintigraphic studies (one image or two images) were independently and retrospectively analyzed by two radiologists (R1 and R2). Sensitivity, specificity (Sp) and predictive values (PV), and were calculated for each type of study (one image or two images) and for each radiologist (R1 or R2). The Se to detect stifle disorders varied between radiologists (29.2% and 20.8%). The Sp was 84.5% and 88.3%. When two images were evaluated a decrease in the positive PV for both readers occurred. The Cohen kappa coefficient (κ) between readers was poor when one image (0.084) or two images (0.117) were evaluated. Findings from this study indicated that bone‐phase nuclear scintigraphy is reasonably specific but highly insensitive for detecting lameness originating from the stifle in a diverse population of both normal and affected horses. The addition of a caudal scintigraphic image acquisition did not improve diagnostic sensitivity.     

ULTRASONOGRAPHIC DIAGNOSIS OF COXOFEMORAL SUBLUXATION IN HORSES

The clinical and ultrasonographic features of seven horses with coxofemoral subluxation are presented. Affected horses included five adult geldings (11–20 years), one large pony (6 years) and a 3-month-old filly. All were lame at the walk except for the pony with grade 3/5 lameness. Lameness was acute in all horses, but three horses progressed after initial improvement. Crepitus, muscle atrophy, and pelvic asymmetry were inconsistent findings. Ultrasonographic diagnosis of subluxation required dynamic visualization of femoral head displacement from the acetabulum while placing weight on the affected limb and subsequent replacement into its normal position upon limb resting. Acetabular rim fractures and joint effusion were visible regardless of weight bearing status in six horses each. No fractures were identified in the pony; the only patient with a good outcome. Six horses had a poor outcome with severe chronic lameness, four of which were euthanized. Postmortem ventrodorsal radiographs obtained in two horses confirmed subluxation only on extended limb projections, but not on hip-flexed projections. Acetabular rim fractures were not visible radiographically in either horse but were confirmed at necropsy. Subluxation was due to an elongated but intact ligament of the head of the femur in both horses. Osteoarthrosis was evident ultrasonographically, radiographically, and at necropsy. Dynamic ultrasonography was readily performed in the standing horse and produced diagnostic images with a low frequency curvilinear transducer. The apparent poor prognosis for horses with subluxation and acetabular fracture illustrate the importance of this imaging technique to identify affected horses.     

SCINTIGRAPHIC ASSESSMENT OF THE METACARPOPHALANGEAL AND METATARSOPHALANGEAL JOINTS OF HORSES WITH JOINT PAIN

Our aims were to evaluate the pattern of radiopharmaceutical uptake in horses with lameness related to the metacarpophalangeal and/or metatarsophalangeal joint and compare the results with similar information from sound horses. It was hypothesized that there would be a difference in radiopharmaceutical uptake between the lame and contralateral limb in unilaterally lame horses and that there would be a difference between lame and sound horses. Nuclear scintigraphic images of 43 horses with forelimb lameness and 30 horses with hindlimb lameness were evaluated. In all horses lameness was improved by intraarticular analgesia of the joint, or by perineural analgesia of the palmar/plantar (at the junction of the proximal 3/4 and the distal 1/4 of the metacarpal/metatarsal regions) and palmar/plantar metacarpal/metatarsal nerves. All images were assessed subjectively and a quantitative image analysis was performed by drawing a vertical line profile through the center of each joint in the lateral images and using region of interest analysis in both lateral and dorsal/plantar images. Ratios of radiopharmaceutical uptake were compared for each region between lame and contralateral limbs in unilaterally lame horses and between lame and control horses. There was a significant difference in the ratio of radiopharmaceutical uptake in the proximal aspect of the proximal phalanx between lame and nonlame forelimbs in unilaterally lame horses and in both lame and contralateral limbs of lame horses compared with control horses for the regions of the distal aspect of the third metacarpal/metatarsal bone and the proximal sesamoid bones. However, the profile analysis was of limited clinical value.     

COMPARISON OF THORACIC ULTRASONOGRAPHY AND RADIOGRAPHY FOR THE DETECTION OF INDUCED SMALL VOLUME PNEUMOTHORAX IN THE HORSE

Small volume pneumothorax can be challenging to diagnose in horses. The current standard method for diagnosis is standing thoracic radiography. We hypothesized that thoracic ultrasonography would be more sensitive. Objectives of this prospective, experimental study were to describe a thoracic ultrasound method for detection of small volume pneumothorax in horses and to compare results of radiography and ultrasound in a sample of horses with induced small volume pneumothorax. Six mature healthy horses were recruited for this study. For each horse, five 50 ml air boluses were sequentially introduced via a teat cannula into the pleural space. Lateral thoracic radiographs and standardized ultrasound (2D and M‐mode) examinations of both hemithoraces were performed following administration of each 50 ml air bolus. Radiographs and ultrasound images/videos were analyzed for detection of pneumothorax by four independent investigators who were unaware of treatment status. Sensitivity, specificity, positive predictive values, negative predictive values, and agreement among investigators (Kappa test, κ) were calculated for radiography, 2D and M‐mode ultrasound. Comparisons were made using a chi‐squared exact test with significance set at P < 0.05. Two‐dimensional (84%) and M‐mode (80%) ultrasound were more sensitive than radiography (48%) for pneumothorax detection (P = 0.02 and P = 0.04, respectively). Specificity and positive predictive values were similar for all three imaging modalities (P = 1). Agreement between investigators for pneumothorax detection was excellent for 2D ultrasound (κ = 1), very good for M‐mode ultrasound (κ = 0.87), and good for radiography (κ = 0.79). Findings from this experimental study supported the use of thoracic ultrasonography as a diagnostic method for detecting pneumothorax in horses.