Biomedical subjects

A J Ruggles

Publications and source records attributed to A J Ruggles.

At least 19 recordsLinked to original sources

PubMed2007

Racing performance after arthroscopic removal of apical sesamoid fracture fragments in Thoroughbred horses age < 2 years: 151 cases (1989--2002).

REASONS FOR PERFORMING STUDY: Studies on arthroscopic removal of apical proximal sesamoid fracture fragments in Thoroughbred (TB) horses age > or = 2 years have reported a high success rate. However, there are no reports documenting the racing prognosis of TB horses that undergo such surgery as weanlings or yearlings. OBJECTIVES: To describe the incidence of apical proximal sesamoid fractures in immature TB horses, age < 2 years and determine probability and quality of racing performance after arthroscopic removal of such fractures in 151 TB weanlings and yearlings. METHODS: The medical records of TB horses age < 2 years that underwent arthroscopic surgery for removal of apical proximal sesamoid fracture fragments were reviewed. Follow-up information was obtained from race records. Student's t tests were used to compare performance variables of operated racehorses to that of their maternal siblings. RESULTS: Ninety-two percent (139/151) of fractures occurred in the hindlimbs and 8% (11/151) in the forelimbs (fracture of both fore- and hindlimb, n = 1). Horses with forelimb fractures had a greatly reduced probability of racing (55%) compared to those with hindlimb fractures (86%). Overall, 84% of the horses raced post operatively and had performance records similar to that of their maternal siblings, 78% (787/1006) of which raced. CONCLUSIONS: Arthroscopic removal of apical proximal sesamoid fracture fragments in TB weanlings and yearlings carries an excellent prognosis for racing in horses with hindlimb fractures and a reduced prognosis in those with forelimb fractures. Medial fractures of the forelimb carry the worst prognosis. POTENTIAL RELEVANCE: The determination of prognosis increases knowledge on apical sesamoid bone fractures and potential for arthroscopic restoration of the ability to race; and enables the value of yearlings for subsequent sale to be established.

Age Factors↗

PubMed2006

Racing performance after arthroscopic removal of apical sesamoid fracture fragments in Thoroughbred horses age > or = 2 years: 84 cases (1989-2002).

REASONS FOR PERFORMING STUDY: Studies have shown that surgical removal of apical fracture fragments in Standardbred racehorses carries the best prognosis for return to racing performance, but there are no reports involving mature Thoroughbred (TB) racehorses. OBJECTIVES: To describe the incidence of apical proximal sesamoid fractures in TB racehorses and determine probability and quality of racing performance after arthroscopic removal of such fractures in TB racehorses age > or = 2 years. METHODS: Medical records and pre- and post operative race records of TB racehorses age > or = 2 years that underwent arthroscopic surgery for removal of apical proximal sesamoid fracture fragments were reviewed. RESULTS: Sixty-four percent of fractures occurred in the hindlimbs and 36% in the forelimbs. Horses with forelimb fractures had a reduced probability of return to racing (67%) compared to those with hindlimb fractures (83%), but the majority (77%) of treated horses recovered to return to race post operatively. Horses with medial forelimb fractures raced at only a 47% rate; those with suspensory desmitis at 63%. Unlike Standardbreds, there was no difference in probability of racing post operatively between horses that had, and had not, raced preoperatively. CONCLUSIONS: Data show that arthroscopic removal of apical proximal sesamoid fracture fragments is successful at restoring ability to race in skeletally mature TB horses without evidence of severe suspensory ligament damage. Prognosis for return to racing is excellent (83%) in horses with hindlimb fractures and good (67%) in those with forelimb fractures. Medial fractures of the forelimb have the worst prognosis. POTENTIAL RELEVANCE: The determination of prognosis for differing sites in TB racehorses should increase knowledge of apical proximal sesamoid bone fractures and improve communication from veterinarian to owner, and trainer, on the potential for arthroscopic restoration of the ability to race.

Age Factors↗

PubMed2000

Long-term outcome of horses with a slab fracture of the central or third tarsal bone treated conservatively: 25 cases (1976-1993).

OBJECTIVE: To determine clinical features of horses with a slab fracture of the central or third tarsal bone and to report outcome of horses in which treatment did not include surgery. DESIGN: Retrospective study. ANIMALS: 25 horses (14 Standardbreds, 6 Thoroughbreds, 5 Quarter Horses). PROCEDURE: Medical records of horses with a slab fracture of the central (n = 9) or third (16) tarsal bone were reviewed. Only horses for which treatment consisted of confinement to a stall were included in this study. Clinical features and radiographic findings were recorded and summarized. Outcome was determined for racing breeds by obtaining official lifetime race results. Outcome for Quarter Horses was determined by phone survey of the owners. RESULTS: 16 (64%) horses had a successful outcome. Ten of 14 (71%) Standardbreds and 2 of 6 Thoroughbreds returned to racing and started at least 5 races after injury. Four of 5 Quarter Horses for which follow-up information was available successfully returned to their previous activity. Sex, age, limb affected, or gait was not associated with final outcome. Percentage of racehorses with central tarsal bone fractures that had a successful outcome (2/7) was significantly less than percentage with third tarsal bone fractures that did (10/13). CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that enforced rest without surgical fixation can be an effective therapeutic option for horses with a slab fracture of the central or third tarsal bone, even if athletic function is expected.

Animals↗

PubMed1999

Apical fracture of the proximal sesamoid bone in standardbred horses: 43 cases (1990-1996).

OBJECTIVE: To determine whether fracture fragment dimensions, suspensory ligament damage, and racing status at the time of injury were associated with outcome in Standardbred horses with apical fracture of the proximal sesamoid bone. DESIGN: Retrospective study. ANIMALS: 43 Standardbred racehorses. PROCEDURE: Medical records, racing records, and radiographs were reviewed, and ultrasonographic findings were scored. Measurements of the fractured portion of the proximal sesamoid bone were made. RESULTS: Seventy-four percent (32/43) of horses were pacers, and 26% (11/43) were trotters. Statistical differences between trotters and pacers regarding ability to start, number of starts, or amount of money earned after injury were not detected. Females earned significantly more money per start after injury than males. Eighty-six percent (37/43) of fractures involved hind limbs and 14% (6/43) involved forelimbs. Horses with forelimb injuries earned less money per start. Severity of suspensory ligament damage did not affect postinjury racing performance. A higher proportion of horses that had raced before injury returned to racing after surgery than horses that had not raced before injury, although a significant difference between these groups was not detected. Eighty-eight percent of horses that raced before injury raced after injury. Fifty-six percent of horses that did not race before injury raced after injury. Fracture fragment dimensions did not affect outcome. CLINICAL IMPLICATIONS: Dimensions of the apical fracture fragment of the proximal sesamoid bone in Standardbred horses and degree of suspensory ligament damage did not affect outcome. Prognosis for return to racing soundness is good in horses that had raced before injury and fair in horses that had not raced before injury.

Animals↗

PubMed1997

Biochemical, histochemical, and immunohistochemical characterization of distal tibial osteochondrosis in horses.

OBJECTIVE: To compare the biochemical, histochemical, and immunohistochemical profiles of articular cartilage from horses with naturally acquired distal tibial osteochondrosis (OC) with cartilage from a similar location in clinically normal horses. ANIMALS: 9 affected horses (group 1, 16 OC lesions) and 4 control horses (group 2, 8 normal osteochondral specimens). PROCEDURE: OC specimens were collected during arthroscopic removal of the fragment, and control specimens were collected by aseptic osteotomy. Uronic acid, total protein, total glycosaminoglycan (GAG), chondroitin sulfate (CS), and keratan sulfate (KS) contents were determined. Histomorphologic, histochemical, and immunohistochemical examinations were performed on specimens after snap freezing at -80 C and cryosectioning. Monoclonal antibodies (MAB) 3B3 and 5D4 were applied for location of epitopes of CS and KS, respectively. RESULTS: OC lesions had significantly lower quantity of uronic acid, total GAG, and CS, compared with normal cartilage. OC cartilage had significantly less intense staining with toluidine blue, along with irregular cellularity and tidemark characteristics, compared with normal cartilage. Monoclonal antibodies 3B3 and 5D4 stained OC cartilage, whereas MAB 5D4 did not stain control cartilage. Additionally, MAB 3B3 and 5D4 stained the fibrous tissue that was found firmly attached to the OC lesion located between the parent distal portion of the tibia and OC fragment. CONCLUSION: OC cartilage lesions of the distal intermediate ridge of the tibia in horses are biochemically, histochemically, and immunohistochemically distinct from normal cartilage from the same location. Results may reflect the inability of the chondrocyte of the developing joint to alter matrix components that would allow proper maturation and differentiation into bone.

Animals↗

PubMed1996

Tibial stress fractures in racing standardbreds: 13 cases (1989-1993).

OBJECTIVE: To determine clinical signs, radiographic and scintigraphic findings, and performance outcome of racing Standardbreds with tibial stress fractures. DESIGN: Retrospective case series. ANIMALS: 13 racing Standardbreds with tibial stress fractures. PROCEDURE: Information concerning clinical signs, diagnostic evaluation, and recommendations was obtained by review of the medical records. Performance information before and after diagnosis of the fracture was collected from racing records, and follow-up information was obtained from the owners or trainers by use of a telephone questionnaire. RESULTS: Horses with tibial stress fractures were moderately lame, and diagnosis was made by nuclear scintigraphy and radiography. Fractures were more likely to occur in 2-year-old horses than in older horses. The fracture location was unique for Standardbreds; 11 of 13 developed stress fractures in the mid-diaphysis of the tibia, whereas fractures in Thoroughbreds are usually in the proximal caudal or caudolateral cortex. Fractures occurred in young horses that had raced or were in advanced race training. All horses were treated with rest alone, and 10 of 13 horses raced after injury. The horses that raced after injury were able to return to a level of performance that was equal to or better than the level raced before injury. 8 of 10 horses established a lifetime-best winning time after injury. CLINICAL IMPLICATIONS: Tibial stress fractures are a cause of lameness in young racing Standardbreds. Diagnosis is aided by nuclear scintigraphy. The prognosis for return to previous level of performance after a tibial stress fracture is good.

Age Factors↗

PubMed1996

Plasma, urine, and synovial fluid disposition of methylprednisolone acetate and isoflupredone acetate after intra-articular administration in horses.

OBJECTIVE--To document plasma, urine, and synovial fluid disposition of 2 common intra-articularly administered steroid preparations, methylprednisolone acetate (MPA) and isoflupredone acetate (IPA). DESIGN--Descriptive investigation. SAMPLE POPULATION--100 mg of MPA or 4 mg of IPA was administered to 2 groups of 4 healthy sound radiographically normal female horses. PROCEDURE--Blood samples were collected at time 0 (before) and 2, 4, 6, 8, 10, 12, 24, 36, 48, 72, and 96 hours after administration of the designated steroid. Complete urine collection for measurement of designated steroid was accomplished by use of occluding 28-F balloon catheters. Synovial fluid samples were aseptically aspirated from the injected and contralateral uninjected tarsocrural joint at time 0 and 8, 24, 48, 240, and 672 hours after administration of the designated steroid. All samples were screened by ELISA to detect parent drug or metabolite equivalent, with a sensitivity of 2.5 ng/ml for MPA and 0.1 ng/ml for IPA. If drug was detected by ELISA in the plasma or synovial fluid, the samples were further quantified and specified, using HPLC with a lower limit of quantification (10 ng/ml). RESULTS--Between 2 and 12 hours after administration, plasma contained < 10 ng of MPA or IPA/ml (parent drug or metabolite equivalent), as intermittently detected by ELISA. Parent drug or metabolite equivalent was detected in the urine for 24 and 72 hours after injection of IPA and MPA, respectively. Synovial fluid from the contralateral joint contained no detectable MPA or IPA at any sample collection time. Median half-life for MPA, as detected by HPLC, was 10.3 hours (range, 6.1 to 10.6) in the synovial space. Median half-life for methylprednisolone, as detected by HPLC, was 10.4 (range, 9.9 to 32.1) hours. CONCLUSIONS--Both steroids appeared to be rapidly hydrolyzed to their respective ester forms, as detected by HPLC. The ELISA appeared to be a useful screening tool for detection of corticosteroids in this variety of body fluids.

Animals↗

PubMed1995

Fracture of the distal sesamoid bone in horses: 17 cases (1982-1992).

Medical records of 17 horses in which a distal sesamoid bone fracture was diagnosed between 1982 and 1992 were reviewed. There were 8 Standardbreds, 6 Quarter Horses, 2 Thoroughbreds, and 1 Arabian. Mean age was 4.7 years. A forelimb was affected in 15 horses, and a hind limb was affected in 2. All horses were lame, and most were grade III/V lame at the trot. In all horses, the diagnosis was confirmed by means of radiography. Five horses were treated with stall rest alone; 5 underwent neurectomy; 4 were treated with stall rest and corrective shoeing; and 1 was treated with stall rest and external coaptation. The other 2 horses were euthanatized. Two Quarter Horses, 1 treated with stall rest and corrective shoeing and the other treated with stall rest and external coaptation, returned to use as halter horses, and 2 Standardbreds treated with stall rest alone returned to racing, but at a lower level than they had raced prior to injury. One horse that underwent neurectomy could be used for pleasure riding. Long-term rest may be important in achieving a successful outcome. Pleasure horses would appear to have a better prognosis for return to use after a distal sesamoid bone fracture than do performance horses.

Animals↗

PubMed1993

Disseminated Halicephalobus deletrix infection in a horse.

A 13-year-old Quarter Horse gelding was referred for evaluation of a draining tract and fracture of the right hemimandible of 4 weeks' duration. Two days prior to admission, the horse had developed pigmenturia. Radiography of the mandible revealed a fracture of the vertical ramus of the right hemimandible, loss of the right lower second premolar, and osteomyelitis involving an extensive portion of the hemimandible. Ultrasonography of the left kidney revealed loss of normal renal architecture. Histologic examination of tissue obtained from the right hemimandible revealed granulomatous osteomyelitis and multiple metazoan parasites identified as Halicephalobus deletrix. The horse was treated with antimicrobial and deworming agents, and the mandible was surgically debrided. The horse became atactic 8 days after surgery and was euthanatized. Necropsy identified parasitic migration in the right hemimandible, kidneys, and CNS.

Animals↗

PubMed1993

Changes in fluid composition on the serosal surface of jejunum and small colon subjected to venous strangulation obstruction in ponies.

In 6 anesthetized ponies, 3 segments of jejunum and 3 segments of small colon were isolated from the peritoneal cavity in plastic bags filled with Hanks' balanced salt solution. One jejunal and 1 small colon segment were subjected to venous strangulation obstruction for 3 hours (VSO-3), venous strangulation obstruction for 6 hours (VSO-6), or a 6-hour sham procedure to control for changes induced by isolation in a plastic bag. Additional segments of jejunum and colon that were not placed in bags served as controls for histologic examination and collagenase measurements. Samples of fluid surrounding the intestine were obtained for chemical analyses, nucleated cell count, aerobic and anaerobic bacteriologic culture, and measurement of collagenase activity. Full-thickness tissue samples were obtained for histologic examination and measurement of collagenase content. Bacteria did not cross the intestinal wall after 3 and 6 hours of VSO, despite severe mucosal lesions in these segments. At 6 hours, PO2 was significantly less and PCO2 was significantly (P < 0.05) greater in the fluid surrounding the VSO-6 jejunal segments, compared with the sham jejunal segments. The pH was significantly (P < 0.05) less in fluid surrounding VSO-6 small colon segments, compared with the sham colon segments at 6 hours. For jejunum and small colon, phosphate and lactate concentrations were significantly (P < 0.05) greater in VSO-6 fluid than in the corresponding sham fluids at 6 hours. Fibrin formed around all VSO segments, although fibrinogen was not detected in the surrounding fluid, indicating possible rapid conversion of fibrinogen to fibrin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Ocular lymphangiosarcoma in a cow.

Ocular lymphangiosarcoma was diagnosed in a Holstein cow with a progressively enlarging limbal mass. The cow was treated by exenteration. The cow survived for 2 years without clinical signs of recurrence. Lymphangiosarcoma is a vascular neoplasm that rarely has been reported in domestic animals. In other species, it has a high rate of metastasis and is associated with poor long-term survival.

Animals↗

PubMed1992

Intraluminal hemorrhage from small intestinal ulceration in two cows.

Two adult Holstein cows were admitted with signs of acute gastrointestinal hemorrhage. Abomasal ulceration was diagnosed tentatively in both cows, but was later ruled out in 1 cow that had an abomasotomy performed through a right paramedian approach. Both cows failed to respond to treatment of blood loss and hypovolemic shock and became recumbent; one cow died and the other was euthanatized. Post-mortem examination determined the source of hemorrhage in both cows to be ulcerated small intestine with severe intraluminal hemorrhage. The cause of ulceration was undetermined. Small intestinal hemorrhage should be considered in cattle with signs of acute gastrointestinal hemorrhage.

Animals↗

PubMed1991

Medical and surgical management of small-colon impaction in horses: 28 cases (1984-1989).

Medical records of 28 horses with impaction of the small colon were reviewed; 20 horses were admitted during the winter months. Diagnosis of small-colon impaction was made in 21 horses by rectal examination, and in 7 horses at exploratory celiotomy. Ten horses were treated medically, and 18 were treated surgically. Horses that were treated surgically were more likely to have abdominal distention than were those that responded to medical treatment (P less than 0.025). Signs of greater degree of abdominal pain and higher heart rate were seen in horses treated surgically, but these values were not significantly different from values in medically treated horses. Duration of hospitalization was less in horses treated medically (P less than 0.025). Long-term survival was higher for horses treated medically (P less than 0.025). All horses treated medically and 7 of the horses treated surgically were alive at follow-up evaluation, at least 1 year after discharge. Fever and diarrhea were common complications after surgery. Four horses were fecal culture-positive for Salmonella sp after surgery. Early and aggressive medical management of horses with impaction of the small colon is recommended.

Animals↗

PubMed1985

Increased ovulation rate of adult ewes treated with anti-bovine LH antiserum during the normal breeding season.

Adult Suffolk ewes (n = 14) were treated on d 10 of the estrous cycle with anti-bovine luteinizing hormone (LH) antiserum. Control ewes (n = 10) were treated with normal horse serum. Estrous behavior and the number of corpora lutea and ovarian follicles were examined at the subsequent estrous cycle. Daily plasma concentrations of progesterone (P4), follicle stimulating hormone (FSH) and estradiol were determined before and after treatment. Ewes treated with antiserum had a higher (P less than .05) ovulation rate (2.7 +/- .2) than did controls (2.1 +/- .1). No differences were found in the numbers of large (greater than 5 mm) or small (less than 5 mm) follicles between treatment groups. Estrus was delayed (P less than .025) approximately .6 d/in ewes treated with antisera. Immunoreactive FSH increased (P less than .05) within 1 d after treatment and remained higher than the controls for 5 d. Peak estradiol concentrations occurred on d 17 for treated ewes compared with peak concentrations on d 15 or 16 for control ewes. The P4 concentrations were generally less (P less than .025) in treated ewes throughout the luteal phase of the treatment cycle. These data demonstrate that ovulation rate is increased in ewes treated with LH antiserum. The marked increase in plasma FSH suggests a possible mechanism whereby ovulation rate is enhanced.

Animals↗

PubMed1985

A seven-day synchronization method for ewes using medroxyprogesterone acetate (MAP) and prostaglandin F2 alpha.

Estrous cycles of adult (n = 27), farm-flock, Suffolk ewes and Polypay range ewes (n = 224) were controlled with medroxyprogesterone acetate (MAP)-impregnated vaginal pessaries inserted (d 0) for 7 d in combination with prostaglandin F2 alpha (PGF2 alpha) injected on d 6. Descriptive criteria of the effects of this treatment regimen on endocrine characteristics of the estrous cycle were evaluated in the experiment with farm-flock ewes. The efficacy of this synchronization regimen on reproductive performance of range-bred ewes was tested in a second trial. Suffolk ewes bred at the second observed estrus after treatment to provide comparisons of cycle length between treated and control ewes. Polypay ewes were exposed to fertile rams at the controlled estrus. Eighty-nine percent of Suffolk ewes were in estrus within 3 d after pessary removal. All nonsynchronized Suffolk ewes (n = 24) were in estrus over a 21-d period. Estrous cycle lengths of treated ewes averaged 16.8 +/- .2 d. Plasma progesterone concentrations were similar for treated and control ewes during the luteal phase of the estrous cycle. Ninety-one percent of the range-bred, controlled ewes lambed. Sixty-two percent of these ewes lambed within 150 d after exposure to fertile rams compared with only 17% of nonsynchronized ewes (P less than .05). Lambing percentage was similar by 167 d for treated (87%) or control (88%) ewes. Lambs per ewe exposed averaged 1.68 and 1.80 for treated and nonsynchronized groups, respectively. These data indicate the effectiveness of this 7-d treatment method for control of the estrous cycle of ewes during the normal breeding season. Results further show that this treatment scheme has practical application for range breeding of ewes.

Animals↗

PubMedDate not supplied

Biodegradable drug delivery systems for gentamicin release and treatment of synovial membrane infection.

OBJECTIVE: This study investigated two biodegradable drug delivery systems (BDDS) for elution of gentamicin and elimination of synovial membrane infection. STUDY DESIGN: The effect of BDDS on control and infected synovial explants was determined. ANIMALS OR SAMPLE POPULATION: Synovial explants from four adult equine cadavers. METHODS: First, BDDS were placed in phosphate buffered saline for 14 days. Eluent was tested for gentamicin concentration (G) and bioactivity. Second, synovial explants were divided into four groups (n = 14/group): Group 1 (control); Group 2 (infected control) 405 cfu Staphylococcus aureus added at 6 hours; Group 3 (antibiotic BDDS [Ab-BDDS]) Ab-BDDS added at 24 hours; Group 4 (infected Ab-BDDS) 405 cfu S. aureus added at 6 hours, Ab-BDDS added at 24 hours. Both types of Ab-BDDS were used (n = 7/type/group). Explants were incubated in standard medium for 4 days. Medium was cultured and analyzed for (G) and hyaluronic acid concentration (HA). Explants were analyzed for viability and morphologic changes. RESULTS: The Ab-BDDS released >500 microg/mL of active gentamicin for 10 days. In Group 3, infection was eliminated within 24 hours, but histologic scores did not return to normal. Viability was significantly reduced by infection, but if eliminated, viability tended to return to normal. In Group 3, the Ab-BDDS had no significant effect on viability or (HA). Histopathologic scores were significantly higher for infected synovium. Infection, even if treated, significantly reduced (HA). CONCLUSIONS: Both Ab-BDDS eliminated infection within 24 hours. However, synovial morphology, viability and function did not return to normal. CLINICAL RELEVANCE: The Ab-BDDS may be useful for treatment of synovial membrane infection.

Absorbable Implants↗

PubMedDate not supplied

In vitro biomechanical properties of 2 compression fixation methods for midbody proximal sesamoid bone fractures in horses.

OBJECTIVE: To evaluate 2 methods of midbody proximal sesamoid bone repair--fixation by a screw placed in lag fashion and circumferential wire fixation--by comparing yield load and the adjacent soft-tissue strain during monotonic loading. STUDY DESIGN: Experimental study. SAMPLE POPULATION: 10 paired equine cadaver forelimbs from race-trained horses. METHODS: A transverse midbody osteotomy of the medial proximal sesamoid bone (PSB) was created. The osteotomy was repaired with a 4.5-mm cortex bone screw placed in lag fashion or a 1.25-mm circumferential wire. The limbs were instrumented with differential variable reluctance transducers placed in the suspensory apparatus and distal sesamoidean ligaments. The limbs were tested in axial compression in a single cycle until failure. RESULTS: The cortex bone screw repairs had a mean yield load of 2,908.2 N; 1 limb did not fail when tested to 5,000 N. All circumferential wire repairs failed with a mean yield load of 3,406.3 N. There was no statistical difference in mean yield load between the 2 repair methods. The maximum strain generated in the soft tissues attached to the proximal sesamoid bones was not significantly different between repair groups. CONCLUSIONS: All repaired limbs were able to withstand loads equal to those reportedly applied to the suspensory apparatus in vivo during walking. CLINICAL RELEVANCE: Each repair technique should have adequate yield strength for repair of midbody fractures of the PSB immediately after surgery.

Animals↗

PubMedDate not supplied

Endoscopic examination of normal paranasal sinuses in horses.

The frontal, caudal maxillary, and rostral maxillary sinuses of 10 equine cadavers were examined endoscopically, and the findings were confirmed by sinusotomy. Similar endoscopic examinations were performed in five conscious, adult horses by using sedation and local anesthesia. Useful portals of entry for the arthroscope in adult horses were: for the frontal sinus, 60% of the distance in a lateral direction from midline to the medial canthus and 0.5 cm caudal to the medial canthus; for the caudal maxillary sinus, 2 cm rostral and 2 cm ventral to the medial canthus; and for the rostral maxillary sinus, 50% of the distance from the rostral end of the facial crest to the level of the medial canthus and 1 cm ventral to a line joining the infraorbital foramen and the medial canthus. The frontal sinus portal was most useful for examination of the frontal and caudal maxillary sinuses. The caudal maxillary sinus portal was most useful for examining the sphenopalatine sinus. Structures in the frontal and caudal maxillary sinuses could be approached surgically by viewing them through the frontal sinus portal and guiding an instrument to them through the caudal maxillary sinus portal. Tooth root identification was reliable for the second and third upper molars in animals older than 5 years, but was more difficult for the rostral teeth and in younger animals. Endoscopy was not difficult to perform and was well tolerated in standing, sedated horses. The only complication of this procedure was mild, local subcutaneous emphysema that resolved spontaneously within 14 days.

Anesthesia, Local↗