Exercising upper respiratory videoendoscopic evaluation of 100 nonracing performance horses with abnormal respiratory noise and/or poor performance.

REASONS FOR PERFORMING STUDY: Although well documented in racehorses, there is paucity in the literature regarding the prevalence of dynamic upper airway abnormalities in nonracing performance horses. OBJECTIVE: To describe upper airway function of nonracing performance horses with abnormal respiratory noise and/or poor performance via exercising upper airway videoendoscopy. METHODS: Medical records of nonracing performance horses admitted for exercising evaluation with a chief complaint of abnormal respiratory noise and/or poor performance were reviewed. All horses had video recordings of resting and exercising upper airway endoscopy. Relationships between horse demographics, resting endoscopic findings, treadmill intensity and implementation of head and neck flexion during exercise with exercising endoscopic findings were examined. RESULTS: Dynamic upper airway obstructions were observed in 72% of examinations. Head and neck flexion was necessary to obtain a diagnosis in 21 horses. Pharyngeal wall collapse was the most prevalent upper airway abnormality, observed in 31% of the examinations. Complex abnormalities were noted in 27% of the examinations. Resting laryngeal dysfunction was significantly associated with dynamic arytenoid collapse and the odds of detecting intermittent dorsal displacement of the soft palate (DDSP) during exercise in horses with resting DDSP was only 7.7%. Exercising endoscopic observations were different from the resting observations in 54% of examinations. CONCLUSIONS: Dynamic upper airway obstructions were common in nonracing performance horses with respiratory noise and/or poor performance. Resting endoscopy was only helpful in determining exercising abnormalities with recurrent laryngeal neuropathy. POTENTIAL RELEVANCE: This study emphasises the importance of exercising endoscopic evaluation in nonracing performance horses with abnormal respiratory noise and/or poor performance for accurate assessment of dynamic upper airway function.

Scapulohumeral osteochondrosis. A retrospective study of 32 horses.

OBJECTIVES: To review the outcome of equine shoulder osteochondrosis (OC) with surgical or conservative treatment. METHODS: Retrospective study of 32 horses, less than two years of age, with scapulohumeral joint (SHJ) OC. The lesion severity was graded based on measurements taken from lateromedial radiographs. Follow-up information was obtained from racing records or telephone conversations with owners. Successful outcome was defined as the ability of the horse to perform its intended use. RESULTS: Sixteen of 32 horses were affected bilaterally (48 joints). Eleven of 16 horses with bilateral OC underwent arthroscopic surgery; five had bilateral arthroscopy, six had unilateral arthroscopy of the most severely affected joint. Eight of 16 horses with unilateral OC underwent arthroscopy. The overall outcome was 'poor'. Only 15.4% (4/26) of potential race horses started a race, whereas 67% (4/6) non-racehorses were 'sound' for the intended use. Statistical analysis evaluating the effect of breed on outcome showed a statistically significant difference. There were no significant interactions between outcome and gender, affected limb, unilateral versus bilateral involvement, treatment or severity of the radiographic lesion. However, radiographic lesion severity on the humerus and glenoid showed significant positive correlation. CLINICAL SIGNIFICANCE: The overall poor prognosis for shoulder OC in young horses appears to be, in part, dependent on breed and intended use. There was not any difference in outcome between surgically and conservatively treated horses.

Correlations between exercising arterial blood gas values, tracheal wash findings and upper respiratory tract abnormalities in horses presented for poor performance.

REASONS FOR PERFORMING STUDY: There are limited data on the correlations between arterial blood gas (ABG) values, tracheal wash (TW) cytology and upper respiratory tract (URT) abnormalities. OBJECTIVES: To identify horses with abnormal exercising ABG, and compare the proportions of horses with abnormal ABG and TW cytology, mucus or URT dysfunction with those with normal ABG results and abnormal TW cytology, mucus or URT dysfunction. METHODS: Medical records of 813 horses presenting to the treadmill facility that had a complete treadmill examination, including ABG analysis, TW and URT endoscopy were selected. Diagnoses, ABG results, TW cytology and URT endoscopy were compared. RESULTS: Two hundred and eleven horses met the study criteria of a complete treadmill examination and could have ABG evaluated. There were no significant differences in the age distribution of horses having normal and abnormal ABG or upper respiratory tract (URT) examinations. There was a significantly higher percentage of geldings with abnormal ABG analysis. In the horses with abnormal URT examinations, there were no differences in the proportion of horses having mucus vs. no mucus. However, in the horses with normal URT, there were a higher percentage of horses with visible mucus in the group with abnormal ABG analysis. The majority of horses had abnormal TW cytology and evidence of prior EIPH, with no differences in proportions between the groups. CONCLUSIONS: Because such a large percentage of horses had evidence of inflammation and/or evidence of prior EIPH on TW cytology, it was not possible to determine the effect of these findings on gas exchange. Mucus was present in a larger percentage of cases with abnormal ABG analysis and normal URT examinations, suggesting that the presence of mucus may affect gas exchange. Standardbreds may be more likely to have abnormal gas exchange than Thoroughbreds. A larger number of horses is needed to determine the significance of these findings. POTENTIAL RELEVANCE: Abnormal TW cytology and endoscopic visualised mucus may contribute to impairment of gas exchange, but they do not specifically predict abnormal ABG analysis.

Dynamic pharyngeal collapse in racehorses.

REASON FOR PERFORMING STUDY: Dynamic pharyngeal collapse (PC) is a condition seen in racehorses that can be career-ending. OBJECTIVES: To characterise and grade PC and describe the effects of PC on athletic performance. METHODS: Medical records were reviewed for 828 horses, of which 49 (6%) records were identified as horses with a primary diagnosis of PC. Tapes of video-endoscopy of the pharynx during exercise were reviewed. Each video recording was assigned a grade (0-4) reflecting the degree of PC and a classification for severity of upper airway obstruction. Earnings per race prior to diagnosis of PC were compared to earnings per race after diagnosis of PC for all horses, as well as performance index (PI). Available exercising arterial blood gases were reviewed for horses with PC. RESULTS: There were 35 (80%) Thoroughbreds (TB), and 9 (20%) Standardbreds (STD). 32 (73%) had a history of making an upper respiratory noise. 4 (9%) grade 1 PC, 8 (18%) grade 2 PC, 26 (59%) grade 3 PC, and 6 (14%) grade 4 PC. Seven (16%) horses were classified as mild PC, 18 (41%) as low-moderate PC, 14 (32%) as high-moderate PC, and 5 (11%) as severe PC. Of 30 horses 11 had abnormally decreased PaO2 and 8 horses had abnormally elevated PaCO2. A significant decrease was found in earnings per race prediagnosis when compared to post diagnosis earnings per race in horses > or =4 years of age (P = 0.003). A significant decrease was also observed for earnings per race prediagnosis when compared to post diagnosis earnings per race in horses with grade 3 PC (P = 0.03) No significant differences were observed in PI before or after diagnosis of PC. CONCLUSIONS: There was a trend for PC to be observed in more TB than STD, and more males than females compared to the general hospital population. Horses with PC significant had decreases in arterial oxygenation. Racing records after a diagnosis of PC in all horses > or = 4 years of age suggesting that older horses have a guarded prognosis for continued success. POTENTIAL RELEVANCE: This study provides a classification system for dynamic pharyngeal collapse and suggests that older racehorses (> or = 4 years of age) diagnosed with PC and all horses with grade 3 PC have a poor prognosis for return to previous level of performance.

Conservative management of 17 horses with nonarticular fractures of the tibial tuberosity.

REASONS FOR PERFORMING STUDY: Fractures of the tibial tuberosity (FTT) are caused by direct trauma, and are the second most commonly reported injury in event horses with stifle trauma. Conservative management of horses with FTT has been advocated, but results and prognosis for this method of therapy are unknown. OBJECTIVES: To report and review the findings of a retrospective study of 17 horses admitted to a veterinary teaching hospital from 1986-2001 with nonarticular FTT that received conservative management. METHODS: Subject details, aetiology of the accident, limb affected, degree of lameness at time of admission, size and degree of displacement of the fracture fragment, complications such as comminution of the fracture fragment or damage to soft tissue structures within the affected stifle, and treatment recommendations were obtained from medical records. Owners and trainers were contacted regarding the horse's return to athletic use. The follow-up period consisted of 11-154 months. RESULTS: Two horses were reportedly sound, but unable to return to competition for unrelated reasons. Of the horses that completed the rehabilitation period, 12/15 (80%) returned to athletic use at the same level as before the injury. Three horses were diagnosed with damage to soft tissue supporting structures of the affected stifle and could not return to their former level of competition. CONCLUSIONS: Concurrent soft tissue damage, diagnosed at the time of the initial injury, was statistically significant in precluding horses from returning to athletic careers. All other variables were found to have no effect upon outcome. POTENTIAL CLINICAL RELEVANCE: This retrospective study suggests that the conservative management of nonarticular FTT is a viable treatment modality in managing athletic equine patients presenting with these fractures.

EIPH: postrace endoscopic evaluation of Standardbreds and Thoroughbreds.

The incidence and severity of exercise-induced pulmonary haemorrhage (EIPH) in the 2 most commonly raced horse breeds, Thoroughbreds (TB) and Standardbreds (STD), were studied, with particular interest in the possible influence of frusemide (F) and/or the breed (or running gait) on EIPH. The appearance of blood within the trachea was semi-quantified using a published 5-point system, with zero assigned when no blood was observed, and numbers 1-4 assigned with increasing amounts of blood. Considering each endoscopic examination as a separate event, approximately 75% of the postrace endoscopic examinations had blood-scores of 1, 2, 3, or 4, regardless of breed or F administration. For horses examined twice, the chances of finding blood-scores of 1 or greater in either of the examinations increased to approximately 95%. All horses examined 3 or more times had endoscopic blood-scores of 1 or greater following one or more races, again, irrespective of the breed or F administration. Mean +/- s.e. 'blood scores' were 1.5 +/- 0.1 and 1.8 +/- 0.2 for TB, and 1.4 +/- 0.2 and 1.2 +/- 0.1 for STD racing with and without prerace F, respectively. Therefore, there was no apparent effect of breed (or possibly racing gait) on EIPH, and no differences in the incidence or severity of EIPH were observed between horses with or without prerace frusemide administration.

Dynamic upper airway changes and arterial blood gas parameters during treadmill exercise.

The primary goal was to investigate the relationship between dynamic upper airway abnormalities and arterial blood gas tensions during exercise. Horses that completed a high-speed treadmill examination consisting of upper-airway videoendoscopy, blood gas evaluation and electrocardiogams and, postexercise, echocardiograms and tracheal washes, were included. An age-matched group of fit, healthy Thoroughbreds, trained to run on a high-speed treadmill, served as controls for blood gas values at specific exercise speeds. One hundred and nineteen horses completed the treadmill examination. Sixty (50%) were Thoroughbreds (TB), 51 (43%) Standardbreds (STD) and 8 (7%) other breeds. Mean +/- s.d. age TB 3.8 +/- 2.2 years and STD 4.0 +/- 1.7 years, with no gender predilection. Fifty-four horses (45%) had abnormal upper respiratory tract (URT) abnormalities alone or in combination with abnormalities in another body system. Thirty-eight (70%) were TB, 14 (26%) were STD and 2 (4%) were other breeds. Of these, 24 (45%) had exercising PaO2 values significantly lower than those observed in healthy TB. Nineteen (35%) horses also had significantly elevated exercising PaCO2. Only 14 (12%) horses had abnormal clinical findings in the URT alone, and of these, only 3 (21%) had an abnormally low PaO2 and/or elevated PaCO2. Multiple URT abnormalities were more commonly associated with abnormal exercising blood gases than were single disorders, but pharyngeal collapse (PC) was much more commonly associated with abnormal values if only one disorder was detected. Fifty-five percent (n = 65) of all cases admitted had no evidence of URT disease. Twenty-two (35%) were TB and 37 (57%) were STD. Twenty (31%) of these had abnormally low PaO2 and 14 (22%) had elevated PaCO2 values. Seventy percent (14) of the horses with abnormal PaO2 were STD, while almost 80% (11) of the horses with elevated PaCO2 were STD. These data suggest that dynamic URT dysfunction can adversely affect gas exchange during exercise. While multiple abnormalities were more commonly associated with gas exchange problems than were single disorders, pharyngeal collapse, either alone or in combination with other URT problems, was the disorder most frequently associated with blood gas abnormalities. Additionally, URT disease was more commonly seen in TB, and the proportion of URT diagnoses in horses with abnormal blood gases reflected this percentage, while STD without URT disease had a much higher incidence of abnormal blood gases than did TB without URT abnormalities.

Spontaneous and precipitated withdrawal with a synthetic cannabinoid, WIN 55212-2.

Physical dependence on the synthetic cannabinoid-receptor agonist R(+)-[2,3-dihydro-5-methyl-3-[(morpholinyl)methyl]pyrrolo[1,2,3-de]-1,4-benzoxazinyl]-(1-naphthalenyl) methanone mesylate (WIN 55212-2) was demonstrated in rats by the use of a chronic continuous infusion. Spontaneous withdrawal, of moderate intensity, was shown for the first time with this class of drugs of abuse. Behavioral withdrawal signs were also elicited after challenge with (N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide.HCl (SR141716A), a specific CB(1) cannabinoid-receptor antagonist. In both instances, the high-dose regimen (4, 8, 16 and 16 mg/kg/day, i.p. on days 1-4, respectively) was sufficient to evoke a typical withdrawal syndrome quantified by the signs wet-dog shakes and facial rubs. These results are discussed relative to those obtained with Delta(9)-tetrahydrocannabinol and anandamide. With Delta(9)-tetrahydrocannabinol, precipitated but not spontaneous or abrupt withdrawal was observed, and this was ascribed to pharmacokinetic properties. Anandamide, which showed little, if any, physical dependence potential, behaved atypically. Possible implications regarding pharmacotherapeutic and human abuse issues are discussed.

Clinical experiences with axial deviation of the aryepiglottic folds in 52 racehorses.

OBJECTIVE: To describe the clinical findings in 52 racehorses with axial deviation of the aryepiglottic folds (ADAF) and to report outcome in 33 of these horses after either rest or transendoscopic laser excision of aryepiglottic fold tissue. STUDY DESIGN: Retrospective study. ANIMAL OR SAMPLE POPULATION: Racehorses admitted for high-speed treadmill (HST) evaluation of poor performance. METHODS: Medical records and videotapes of resting and exercising videoendoscopic examinations were reviewed. Racing performance records and owner or trainer interviews, at least 1 year after HST examination, were used to compare results after either surgical management or rest in 33 horses with ADAF and no other upper-airway abnormalities. RESULTS: ADAF occurred in 6% of horses evaluated for poor performance. No breed or gender predisposition existed, but horses with ADAF were younger than the overall population evaluated on the HST. Of 52 horses with ADAF, 19 horses had at least one other upper-airway abnormality. There was no apparent association between ADAF and other causes of dynamic upper-respiratory obstruction. Surgical correction was successfully performed in standing or anesthetized horses without complications. When ADAF was the only upper-airway obstruction, 75% of horses that had surgery and 50% of rested horses had objective improvement in performance. Owners and trainers also perceived greater improvement in performance in horses that had surgery. CONCLUSIONS: Whereas surgical management of ADAF is recommended, clinical experience indicated that it is not required to resolve ADAF in all horses. However, owners and trainers of horses that had surgery were more satisfied with outcome than those with horses managed conservatively. CLINICAL RELEVANCE: Diagnosis of ADAF can only be made by videoendoscopic evaluation during high-speed exercise. Transendoscopic laser excision of the collapsing portion of the aryepiglottic folds can be performed safely in standing horses and results in resolution of airway obstruction and rapid return to training.

Causes of poor performance of horses during training, racing, or showing: 348 cases (1992-1996).

OBJECTIVE: To determine results for horses undergoing a high-speed treadmill examination, including videoendoscopy of the pharynx and larynx before and during exercise, echocardiography before and after exercise, and electrocardiography before, during, and after exercise, because of poor performance. DESIGN: Retrospective study. ANIMALS: 348 horses. RESULTS: A definitive diagnosis was obtained for 256 (73.5%) horses. One hundred forty-eight horses had dynamic obstruction of the airway during exercise, 33 had clinically important cardiac arrhythmias alone, 22 had a combination of dynamic airway obstruction and clinically important cardiac arrhythmias, 19 had poor cardiac fractional shortening immediately after exercise, 10 had exertional rhabdomyolyis, 15 had clinically apparent lameness, and 9 had other disorders. Thirty-nine of the horses with dynamic obstruction of the airway during exercise had multiple airway abnormalities. Fifty-three horses also had subclinical myopathy CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that a complete evaluation, including a high-speed treadmill examination, should be conducted in horses with poor performance, regardless or whether horses do or do not have a history of abnormal respiratory noises and particularly if the horses have grade-II or -III left laryngeal hemiplegia.

Physical examination of horses with back pain.

The diagnosis of back pain is often a diagnosis of exclusion of other problems in the face of poor performance. It requires careful observation, thought, an open mind, and experience. The signs of back pain can be extremely variable and range from subtle to obvious. Obvious forelimb or hind limb lameness is not usually a sign of back pain. The most common differential diagnosis may be back pain secondary to degenerative joint disease of the hocks, fetlocks, or stifle. These diseases can mimic signs of back pain including lack of impulsion, shortening of the stride length, and change in the stride character similar to those seen with back pair.

Cytologic examination of specimens obtained by means of tracheal washes performed before and after high-speed treadmill exercise in horses with a history of poor performance.

OBJECTIVE: To evaluate results of cytologic examination of specimens obtained by means of tracheal washes (TW) in 42 horses with a history of poor performance. DESIGN: Cross-sectional case series. ANIMALS: 42 horses with a history of poor performance. PROCEDURE: A TW was performed via endoscopy before and after horses exercised on a high-speed treadmill, and specimens were evaluated microscopically and graded. RESULTS: Ten (24%) horses were considered to be clinically normal before and after exercise. Pulmonary hemorrhage was diagnosed in 8 (19%) horses. One horse had evidence of exercise-induced pulmonary hemorrhage (EIPH) before exercise and pulmonary hemorrhage and allergic or inflammatory airway disease (IAD) after exercise. Five (12%) horses had IAD, and 1 had IAD and pulmonary hemorrhage after exercise. Seven (17%) horses had evidence of EIPH and IAD in both specimens. Four (10%) horses with EIPH had an increase in the proportion of hemosiderophages in the specimen obtained after exercise. Specimens obtained before exercise in 6 (14%) horses were not representative of the respiratory tract and could not be compared with specimens obtained after exercise. CLINICAL IMPLICATIONS: Interpretation of TW specimens obtained before and after exercise differed for only 5 of 36 (14%) horses. Specimens obtained after exercise were more likely to reveal airway disease. All specimens obtained after exercise adequately represented the respiratory tract, whereas 6 specimens obtained before exercise did not. Specimens obtained after exercise contained more airway secretions and had less cytologic evidence of pharyngeal contamination. Therefore, we recommend that TW samples be obtained after exercise in horses.

Cecocolic and cecocecal intussusception in horses: 30 cases (1976-1996).

OBJECTIVE: To determine the prognosis in horses with cecocolic or cecocecal intussusception. DESIGN: Retrospective study. ANIMALS: 30 horses with cecocolic intussusception or cecocecal intussusception. PROCEDURE: Information on history, physical examination findings, and laboratory values was summarized from the medical records. Laboratory data included results of hematologic examination, serum biochemical analysis, and peritoneal fluid color, total nucleated cell count, and total protein concentration. A one-year follow-up via the telephone was used to determine long-term survival. RESULTS: Horses ranged from 7 months to 30 years old, but 63% were < or = 3 years. Standardbred horses were significantly overrepresented. Twenty-six horses had acute-to-subacute disease, and 4 had a chronic wasting disease. Cecal intussusceptions were suspected on the basis of finding a mass on abdominal palpation per rectum (14 of 24 horses) and positive ultrasonographic findings (2 of 3 horses). Thirteen horses with colic for > 1 day had scant, soft feces. Six horses died or were euthanatized without undergoing surgery, and 24 were treated surgically. Six of the latter horses were euthanatized during surgery because of peritonitis, rupture of the cecum, and irreducible intussusception. All 4 horses with a chronic disease were euthanatized because of irreversible changes in the cecum. Of the 18 horses allowed to recover from surgery, 15 survived long-term. Surgical treatments were reduction, with or without partial typhlectomy (6 horses), partial typhlectomy through a colotomy and reduction (6), reduction through a colotomy and partial typhlectomy (3), partial typhlectomy for a cecocecal intussusception (1) and an ileocolostomy (2). CLINICAL IMPLICATIONS: Cecal intussusception has a good prognosis with surgical correction without delay. Reduction through colotomy has a high success rate. Bypass by ileocolostomy should be used as a last resort.

Videoendoscopic assessment of dynamic laryngeal function during exercise in horses with grade-III left laryngeal hemiparesis at rest: 26 cases (1992-1995).

OBJECTIVE: To evaluate laryngeal function by means of videoendoscopy during high-speed treadmill exercise in racehorses with grade-III left laryngeal hemiparesis at rest and to determine outcome of treatment. DESIGN: Retrospective study. ANIMALS: 26 racehorses. PROCEDURE: Videoendoscopy of the larynx was performed while horses were at rest and exercising on a treadmill. Horses were classified as having grade-IIIA, -IIIB, or -IIIC laryngeal hemiparesis on the basis of the degree of arytenoid cartilage abduction maintained during exercise. Postoperative racing performance was determined by evaluating race records and conducting telephone surveys. RESULTS: 20 (77%) horses had grade-IIIC laryngeal hemiparesis (i.e., severe dynamic laryngeal collapse during exercise). Eighteen underwent surgery, and racing performance was improved in 9. Five (19%) horses had grade-IIIB laryngeal hemiparesis (i.e., left arytenoid cartilage and vocal fold were maintained in an incompletely abducted position during exercise). Four underwent surgery, and racing performance was improved in 1. One (4%) horse had grade-IIIA laryngeal hemiparesis (i.e., full abduction of arytenoid cartilage during exercise); surgery was not performed. CLINICAL IMPLICATIONS: Videoendoscopy is useful in determining dynamic laryngeal function in racehorses with grade-III laryngeal hemiparesis at rest.

Transendoscopic contact neodymium:yttrium aluminum garnet laser treatment of tympany of the auditory tube diverticulum in two foals.

Tympany of the auditory tube diverticulum was treated in 2 Standardbred foals by fenestrating the median septum, using an endoscopically placed Nd:YAG laser. Recurrence in 1 foal was treated by enlarging the fenestration, using a modified Whitehouse approach, and the pharyngeal opening of the auditory tube. Use of the Nd:YAG laser eliminates the risk of inadvertent cranial nerve damage associated with incisions into the auditory tube diverticulum. The procedure can be performed with the horse sedated or anesthetized. Clinical signs can recur in the fenestration heals closed or if the condition is bilateral rather than unilateral.

Dorsomedial articular fracture of the proximal aspect of the third metacarpal bone in standardbred racehorses: seven cases (1978-1990).

Seven Standardbred horses, all pacers, with a mean age of 2.9 years (range, 2 to 4 years), had dorsomedial articular fracture of the proximal aspect of the third metacarpal bone. Fracture caused acute, unilateral, severe lameness after training or racing. Lameness was abolished by midcarpal joint anesthesia in 4 horses. Six horses had a palpable bony swelling, which caused signs of pain. Radiography revealed a nondisplaced, articular, oblique fracture extending distad toward the dorsomedial cortex for a mean distance of 28 mm (range, 15 to 40 mm). In all horses, chronic periosteal proliferative changes, seen near the distal aspect of the fracture, corresponded to palpable bony exostoses and were associated with the medial attachment of the extensor carpi radialis tendon. In 1 horse, internal fixation followed by a 6-month rest resulted in a successful outcome. All other horses were given 3 months' rest without surgery and were not lame. Five horses raced successfully and lowered the lifetime race records, 1 horse was sound and trained successfully, but died of colic, and 1 horse was not lame in early training.

Ejaculatory failure associated with aortic-iliac thrombosis in two stallions.

Two mature breeding stallions were evaluated because of specific ejaculatory dysfunction, and each was found to have aortic-iliac thrombosis occluding 60 to 70% of the aortic lumen. In each case, the stallion had strong libido, normal mounting, and vigorous initial thrusting. With continued exertion, thrusting became weak and dismount was awkward. Treatment aimed at maximizing sexual arousal before mounting and reducing hind limb pain and exertion during breeding allowed these stallions to continue breeding. A program of gradually increasing daily exercise also was associated with improved breeding performance during subsequent breeding seasons. In cases of specific ejaculatory dysfunction, aortic-iliac disease should be included among the differential diagnoses.

Closed suction drainage in the treatment of infectious arthritis of the equine tarsocrural joint.

Infectious arthritis of the tarsocrural joint was treated in 13 horses with closed suction drainage through a flat, fenestrated, latex (Jackson-Pratt) drain, broad-spectrum antimicrobial agents, nonsteroidal anti-inflammatory drugs, and bandage immobilization. In 11 horses, arthroscopic lavage and debridement were also performed. Ingress drains were placed for lavage in six horses. Ten horses returned to their previous level of competition or were sound. One horse raced but had lameness of the affected tarsocrural joint and dropped in racing class; one horse was euthanatized because of laminitis in the supporting limb; and one horse was lame, but useful as a breeding animal. Closed suction drainage appeared to be a useful treatment in horses with infectious arthritis. Although arthroscopy was not necessary, it facilitated fibrin removal, lavage, and partial synovectomy. Because of the development of Pseudomonas superinfection in one horse, the use of simultaneous ingress catheters was not recommended.