Treatment with continuous intrasynovial antimicrobial infusion for septic synovitis in horses: 31 cases (2000-2003)

OBJECTIVE-To determine clinical findings, complications, and outcome of septic synovitis in which continuous intrasynovial antimicrobial infusion (CIAI) was used for local antimicrobial delivery in horses. DESIGN-Retrospective case series. Animals-22 adult horses and 9 foals (horses<1 year of age). PROCEDURES-Records of horses with septic synovitis that had CIAI during treatment were reviewed. The association between clinical variables and whether horses performed their intended use following treatment was determined. RESULTS-42 synovial cavities were treated via CIAI. Twenty-nine cases were chronic (>7 days) in nature, 15 had been refractory to standard treatments, and 13 synovial infections had associated osteomyelitis. Mean duration from infection to initiation of CIAI was 19.7 days, and mean duration of CIAI was 6.1 days. Temporary discharge from the catheter site at the time of removal was evident in 8 horses. Dysfunction of the infusion system occurred in 2 horses and was corrected during the course of treatment. No long-term complications were reported. Thirty-nine (93%) synovial infections in 29 (94%) horses were resolved. Twenty adult horses and 8 foals were discharged from the hospital, and 19 of 24 horses with long-term follow-up performed their intended use. CONCLUSIONS AND CLINICAL RELEVANCE-CIAI was a useful adjunctive treatment for septic synovitis and allowed intrasynovial antimicrobial delivery into a variety of synovial cavities.     

Heel bulb lacerations in horses: 101 cases (1988-1994)

OBJECTIVE: To determine clinical history, structures involved, treatment, and outcome of lacerations of the heel bulb and proximal phalangeal region (pastern) in horses. DESIGN: Retrospective study. ANIMALS: 101 horses. PROCEDURES: Medical records of horses with lacerations of the heel bulb and pastern were reviewed, and follow-up information was obtained. RESULTS: 75 horses were Quarter Horses. Most horses were not treated with antimicrobial drugs prior to referral. Mean +/- SD time from injury to referral was 24 +/- 45 hours (range, 1 to 168 hours). Lacerations were most frequently caused by contact with wire or metal objects. In 17 horses, lacerations involved synovial structures; the distal interphalangeal joint was most commonly affected. One horse was euthanatized after initial examination. Wound treatment consisted of cleansing, lavage, debridement, lavage of affected synovial structures, suturing of fresh wounds, and application of a foot bandage or cast. Fifty-six horses were treated with systemically administered antimicrobial drugs. Follow-up information was collected for 61 horses. Fifty-one horses returned to their intended use and had no further complications; 10 horses had complications associated with the wound, and of those horses, 5 were euthanatized and 1 horse died from an unrelated cause. Horses with lacerations that involved synovial structures had worse outcomes than horses with lacerations that did not involve synovial structures. CONCLUSIONS AND CLINICAL RELEVANCE: Horses that sustain heel bulb lacerations can successfully return to their intended use. Involvement of the distal interphalangeal joint is associated with poor prognosis.     

Septic arthritis in 15 standardbred racehorses after intra-articular injection.

Case histories, results of synovial fluid analyses, treatment regimens and outcome are described for 15 adult Standardbred horses with confirmed post-injection septic arthritis. Joint sepsis followed injection of corticosteroids, hyaluronic acid, polysulphated glycosaminoglycan, or local anaesthetic. The median interval from injection to appearance of clinical signs was 2.5 days, and median interval from injection to referral was 9 days. The median initial synovial leucocyte count on admission was 57 x 10(9)/litre, but there was a wide range of values (18-258 x 10(9)/litre). The median synovial neutrophil percentage was 95% (77-99%). All bacterial isolates were Gram-positive cocci, 86% of which were staphylococci. All treated horses (12/15) initially received broad-spectrum parenteral antibiotic therapy, and the articulations of all horses except one were lavaged, either with non-surgical through-and-through techniques only (N = 3), or surgically with arthrotomy (N = 1) or arthroscopy (N = 7). The owners of all treated horses were contacted and racing records were consulted. Eleven of 12 horses returned to racing. Outcome was judged as either satisfactory (3/12) if the horse had returned to racing levels similar to or better than before treatment, or unsatisfactory (9/12) if the horse had poorer performance or could not return to racing. The 3 horses with satisfactory follow-up had been treated with arthroscopy and post-surgical closed suction drainage. The results of bacterial cultures suggest that the initial antimicrobial agents used should be effective against penicillin-resistant staphylococci.     

Long-term management of sabulous cystitis in five horses

Five horses with sabulous cystitis were managed for up to three years. They were treated by emptying the bladder through a urinary catheter and saline lavage with cytoscopic guidance to remove residual sabulous material. The cystitis was treated with antimicrobial and anti-inflammatory medications, and bethanechol chloride was also administered. Frequent catheterisation and emptying of the bladder was an alternative to regular cystoscopic examination with saline lavage but it resulted in the development of a urethral stricture in one case. Four of the horses returned to work and one was retired owing to persistent incontinence.     

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.     

Septic Arthritis of the Distal Interphalangeal Joint in 12 Horses

The medical records of 12 horses with septic arthritis of a distal interphalangeal joint were reviewed to determine clinical features and response to treatment. Sepsis was caused by trauma or an injection that resulted in an open or contaminated distal interphalangeal joint. All horses were severely lame. Treatment included broad-spectrum parenterally administered antimicrobial drugs (ten horses), percutaneous through-and-through joint lavage (eight horses), indwelling drains (three horses), immobilization of the limb in a cast (three horses), intraarticular injection of sodium hyaluronate (one horse), intraarticular injection of antimicrobial drugs (five horses), curettage of the distal phalanx (one horse), and cancellous bone grafting to promote fusion (one horse). Five horses were euthanatized. Ankylosis of the affected joint developed in five horses, four of which are pasture sound. Two horses treated medically are sound although one underwent subsequent palmar digital neurectomy for treatment of navicular syndrome.     

Endoscopic surgery in the treatment of contaminated and infected synovial cavities

REASONS FOR PERFORMING STUDY: Contamination and infection of synovial cavities are a common occurrence in clinical practice and, if inadequately treated, may have career or life threatening consequences for affected horses. HYPOTHESIS: The objectives in treating contamination and infection of joints, tendon sheaths and bursae are most effectively met by endoscopic surgery. METHODS: Over a 6 year period, cases of synovial contamination and infection admitted to a referral clinic were evaluated and treated endoscopically. The horses received local and systemic antimicrobial drugs with minimal nonsteroidal anti-inflammatory medication but no other medical or surgical treatment. All arthroscope and instrument portals and, whenever possible, all traumatic wounds were closed. Diagnostic information, endoscopic observations and results of treatment were evaluated retrospectively. RESULTS: A total of 140 affected animals were referred and 121 cases were treated endoscopically. These involved 70 joints, 29 tendon sheaths, 10 bursae and in 12 cases a combination of synovial cavities. The most common aetiologies were open wounds (n = 54) and self-sealing punctures (n = 41). Foreign material was identified endoscopically in 41 but predicted prior to surgery in only 6 cases. Osteochondral lesions were evident at surgery in 51 and recognised before surgery in 25 cases; 32 horses had intrathecal tendon or ligament defects. Follow-up information was obtained for 118 animals; 106 (90%) survived and 96 (81%) returned to their preoperative level of performance. The presence of osteitis/osteomyelitis, other osteochondral lesions and marked deposits of pannus were associated with nonsurvival. For those animals which survived, non-Thoroughbred horses, a combination of synovial structure involvement and regional i.v. antimicrobial administration were associated with reduced post operative performance. Marked pannus, regional i.v. antimicrobial administration and duration of systemic antimicrobial administration were associated with a group combining nonsurviving animals and those with reduced post operative performance. CONCLUSIONS: Endoscopic surgery makes a valuable contribution to the management of synovial contamination and infection. POTENTIAL RELEVANCE: The information obtained from and therapeutic options offered by endoscopy justify its early use in cases of synovial contamination and infection.     

Pericarditis in horses: six cases (1982-1986)

Records of 6 horses with pericarditis were reviewed. Septic pericarditis was suspected in all horses, based on historic and clinical findings. In horses 1, 2, and 4, cytologic examination of the pericardial effusion revealed acute inflammation with severe neutrophil degeneration. In horses 3 and 5, cytologic examination of pericardial fluid revealed subacute inflammation with degenerated neutrophils, and in horse 6, chronic active inflammation, with well preserved neutrophils. In horses 1 and 3, bacteria were identified on cytologic examination of pericardial fluid. Results of microbiologic cultures of pericardial fluid were positive in horse 3. All horses were treated with broad-spectrum antibiotics. An indwelling pericardial catheter was used to lavage and directly administer antibiotics into the pericardial sac. Horses 1, 4, 5, and 6 survived, horse 2 died of unrelated causes, and horse 3 was euthanatized at the owner's request. Surviving horses returned to athletic performance.     

Metacarpophalangeal Joint Synovial Pad Fibrotic Proliferation in 63 Horses

Medical records, radiographs, and sonograms of 63 horses with metacarpophalangeal joint synovial pad proliferation were examined retrospectively. All horses had lameness, joint effusion, or both signs associated with one or both metacarpophalangeal joints. Bony remodeling and concavity of the distodorsal aspect of the third metacarpal bone (Mc3) just proximal to the metacarpal condyles was identified by radiography in 71 joints (93%); 24 joints (32%) had radiographic evidence of a chip fracture located at the proximal dorsal aspect of the proximal phalanx. Fifty-four joints (71%) were examined by ultrasound. The mean ± SD sagittal thickness of the synovial pad was 11.3 ± 2.8 mm. Seventy-nine percent of the horses had single joint involvement with equal distribution between the right and left forelimbs. Sixty-eight joints in 55 horses were treated by arthroscopic surgery. Sixty joints (88%) had debridement of chondral or osteochondral fragmentation from the dorsal surface of Mc3 beneath the synovial pad and 30 joints (44%) had a bone chip fracture removed from the medial or lateral proximal dorsal eminence of the proximal phalanx. Complete or partial excision of both medial and lateral synovial pads was completed in 42 joints. Only the medial synovial pad was excised or trimmed in 21 joints, and 5 joints had only the lateral pad removed. Eight joints in eight horses were treated by stall rest, administration of intra-articular medication and systemic nonsteroidal anti-inflammatory drugs. Follow-up information was obtained for 50 horses treated surgically and for eight horses treated medically. Forty-three (86%) that had surgery returned to racing; 34 (68%) raced at an equivalent or better level than before surgery. Three (38%) of the medically treated horses returned to racing; only one horse raced better than the preinjury level. Horses that returned to racing at a similar or equal level of performance were significantly younger in age than horses returning at a lower level or not racing (P≤.05). Overall, horses with synovial pad proliferation treated by arthroscopic surgery had a good prognosis for return to racing at a level equal or better than before injury.     

Open drainage, intra-articular and systemic antibiotics in the treatment of septic arthritis/tenosynovitis in horses.

Open drainage was used to treat 26 horses with persistent or severe septic arthritis/tenosynovitis. Infected synovial structures were drained through a small (3 cm) arthrotomy incision that was left open and protected by a sterile bandage. Joint lavage was performed in all 26 horses. In addition to systemic antibiotics, 23 of these horses were also treated with intra-articular antibiotics; amikacin (17 horses), gentamycin (2 horses), cefazolin (2 horses), and 2 horses were injected at different times with gentamycin and amikacin. The infection was eliminated from the involved synovial structures in 25 of 26 horses; 24 survived and were released from the hospital. The arthrotomy incisions healed by granulation in 16 horses; in 9 horses the arthrotomy incision was sutured closed once the infection was eliminated. Seventeen horses returned to soundness and resumed athletic function. Open drainage was an effective method of achieving chronic drainage from a joint or tendon sheath. It is indicated in horses that have established intra-synovial infections or in horses that do not respond to joint lavage through needles.     

Septic tenosynovitis in horses: 25 cases (1983-1989).

The medical records of 25 horses with septic tenosynovitis treated over 7 years (1983 to 1989) were reviewed to determine clinical features of the disease and response to treatment. The median age of horses with septic tenosynovitis was 5 years (range, 1 month to 21 years). Fourteen fore limbs and 11 hind limbs were affected. Sepsis was located in the sheath of the digital flexor tendons of 22 horses. Sepsis was located in the sheath of the extensor carpi radialis tendon (1 horse), sheath of the long digital extensor tendon (1 horse), or sheath of the common digital extensor tendon (1 horse) in the remaining horses. Nine horses received only medical treatment, using a combination of broad-spectrum parenterally administered antimicrobial drugs (8 of 9 horses), nonsteroidal anti-inflammatory drugs (8 of 9 horses), or irrigation of the wound (4 of 9 horses). Fourteen horses were treated surgically with either transection of the palmar/plantar annular ligament of the metacarpo/metatarsophalangeal joint (5 of 14 horses), lavage of the sheath after insertion of drains into the sheath (7 of 14 horses), or both (2 of 14 horses). All horses treated surgically were concurrently treated parenterally with broad-spectrum antimicrobial drugs and nonsteroidal anti-inflammatory drugs. Two horses with septic tenosynovitis were not treated and were euthanatized at the owners' request. Five horses were euthanatized before discharge from the hospital. Two horses (both treated medically) were lost to follow-up. Follow-up information was obtained for 18 horses, 6 to 55 months after discharge from the hospital.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of Four Antimicrobial Lavage Solutions on the Tarsocrural Joint of Horses

Three concentrations of povidone-iodine (0.1% w/v, 0.2% w/v, 0.5% w/v) and one concentration of chlorhexidine (0.5% w/v) were selected as antimicrobial joint lavage solutions. Through-and-through joint lavage was performed with one of these antimicrobial solutions on a tarsocrural joint of 12 horses. The contralateral tarsocrural joints (control limbs) were lavaged with a balanced electrolyte solution (BES). The effect of the lavage solution on the joints was evaluated with respect to lameness, foot flight pattern, soreness to joint palpation, articular and periarticular enlargement, and synovial fluid composition on Day 1,4, and 8 postlavage. On Day 8 postlavage, all horses were euthanized and the tarsocrural joints were examined.
All solutions induced a synovitis. Based on clinical assessment, synovial fluid protein levels, color, clarity, mucin clot forming ability, gross appearance of the joint at necropsy, and synovial membrane histologic evaluation, a similar, mild, transient, synovitis was induced by the BES and 0.1% povidone-iodine (PI) solution. The 0.2% PI solution induced a more prolonged neutrophilic response and poorer mucin clot forming ability in the synovial fluid as compared to the BES.
The 0.5% PI and 0.5% chlorhexidine solutions produced severe lameness, soreness to joint palpation, and limb enlargement. The elevated synovial fluid total protein content persisted significantly longer (p < 0.05) than the corresponding control (BES) solution. Histologic evaluation of the synovial membrane confirmed the presence of a moderate to severe neutrophilic synovitis in these treatment groups.     

Synovial fluid and plasma concentrations of ceftiofur after regional intravenous perfusion in the horse

OBJECTIVE: To determine radiocarpal (RC) joint synovial fluid and plasma ceftiofur concentrations after regional intravenous perfusion (RIP) and systemic intravenous (IV) administration. STUDY DESIGN: Experimental cross-over study. ANIMALS: Five normal adult horses. METHODS: One RC joint was randomly selected for RIP and the contralateral RC joint was sampled to determine intrasynovial ceftiofur concentrations after IV administration. Wash-out between IV and RIP was > or = 14 days. After surgical introduction of an intraarticular catheter, ceftiofur (2 g) was administered under general anesthesia either IV or by RIP after tourniquet application. Plasma and synovial fluid were collected over 24 hours. Samples were analyzed using high-performance liquid chromatography with ultraviolet detection and the results were statistically analyzed using a linear mixed effect model. RESULTS: Mean synovial fluid ceftiofur concentrations were consistently higher after RIP than after IV administration and were > 1 mug/mL (minimal inhibitory concentration [MIC] for common pathogens) for >24 hours. Mean synovial fluid peak concentration of ceftiofur after RIP and IV administration was 392.7+/-103.29 microg/mL at 0.5 hours postinjection (HPI) and 2.72+/-0.31 mug/mL at 1 HPI, respectively. Large variations in synovial fluid and plasma ceftiofur concentrations were observed between horses regardless of administration technique. RIP did not cause adverse effects. CONCLUSIONS: Under the present experimental conditions RIP with ceftiofur (2 g) induced significantly higher intraarticular antibiotic concentrations in the RC joint in comparison with IV administration. Moreover, after RIP, synovial fluid ceftiofur concentrations remain above the MIC for common pathogens (1 microg/mL) for > 24 hours. No adverse effects from the technique or the antibiotic were observed. CLINICAL RELEVANCE: RIP with high doses of ceftiofur may be a beneficial adjunctive therapy when treating equine synovial infections which are caused by cephalosporin susceptible microorganisms.     

Tenoscopic examination and proximal annular ligament desmotomy for treatment of equine "complex" digital sheath tenosynovitis

OBJECTIVE: To determine the outcome of horses with "complex" digital tenosynovitis treated by tenoscopic proximal annular ligament desmotomy and resection of synovial masses or adhesions, or both, within the digital sheath. STUDY DESIGN: Retrospective evaluation. ANIMALS OR SAMPLE POPULATION: Twenty-five horses with a clinical and ultrasonographic diagnosis of palmar or plantar proximal annular ligament constriction and ultrasonographic evidence of synovial masses or adhesions within the digital tendon sheath. METHODS: Each horse had tenoscopic surgery for annular ligament desmotomy combined with adhesiolysis and/or synovial mass resection. Mean follow-up time was 3.4 years. Spearman's rank correlation was used to assess the relationship between functional outcome or cosmetic results and preoperative variables including duration of clinical signs, digital sheath synovial fluid total protein concentration and nucleated cell count, thickness of the palmar or plantar proximal annular ligament (PAL), severity of adhesions, severity of synovial masses, degree of synovial distention, or limb affected. RESULTS: A total of 18 (72%) horses returned to athletic soundness, 4 were improved but not sound, and 3 were not improved. Cosmetic outcome was normal in 10 horses, improved but not normal in 12, and not improved in 3 horses. Cosmetic and functional outcome were significantly adversely affected by the duration of clinical signs and the severity of synovial masses. CONCLUSIONS: With appropriate tenoscopic surgical attention, horses with complex tenosynovitis syndrome characterized by synovial masses, adhesions, or both adhesions and masses, and PAL constriction, have a good prognosis for return to athletic soundness. CLINICAL RELEVANCE: Horses with PAL constriction and additional digital tendon sheath pathology such as adhesions and synovial masses have a 72% chance of returning to sound athletic performance, however 60% of horses retain some degree of cosmetic blemish in the affected limb. There is an inverse relationship between the duration of clinical signs and outcome, and therefore, prompt surgical attention is advised.     

Arthroscopic laser extirpation of metacarpophalangeal synovial pad proliferation in eleven horses

A new surgical technique for treatment of chronic metacarpophalangeal synovial pad proliferation in the horse and the findings and long-term follow-up from 11 clinical cases are described. The medical records of all equine lameness cases attributed to metacarpophalangeal synovial pad proliferation admitted to the College of Veterinary Medicine at Cornell University (1991-1996) were reviewed and all those treated surgically by laser extirpation were included in this study. Retrieved data included subject details, preoperative lameness, ultrasonography, radiography and synovial fluid evaluations and lesion histopathology. Lesions were ablated using a CO2 or a Nd:YAG laser intra-articularly with arthroscopic guidance. Long-term follow-up was provided by telephone conversation with owners or trainers. All horses had fetlock joint effusion and were lame at presentation. Mean synovial pad thickness measured ultrasonographically was 9.0 mm (range 6-15 mm). Seven horses (64%) had radiographic evidence of remodelling of the dorsal cortex of distal McIII and 3 horses (27%) had concurrent dorsal proximal P1 fractures. No postoperative complications were noted. All 11 horses returned to training within 90 days of surgery without recurrence of the lesion(s). Laser extirpation of metacarpophalangeal synovial pad proliferation using arthroscopic guidance provided a rapid, safe and efficient method for surgical removal of such lesions without complications or recurrence. This surgical technique provides a suitable alternative to more conventional treatments for chronic metacarpophalangeal synovial pad proliferation in horses, particularly for removal of very large, fibrotic masses.     

Evaluation of immune complexes and collagen type-specific antibodies in sera and synovial fluids of horses with secondary osteoarthritis

Thirty-one horses with secondary osteoarthritis as a sequel of trauma (chip fractures) or osteochondritis dissecans were screened for immune complexes (IC) and anticollagen antibodies. Eighty-two percent of horses with joint disease had circulating C1q-binding IC; 77% of those horses had IC in synovial fluids of affected joints. Although only a few horses had anticollagen type-II antibodies, anticollagen type-I antibodies were found in sera of 25% of the horses and in 41% of their synovial fluids. This correlated well with the clinical data and suggested that antibodies might have been elicited by antigens derived from detached intra-articular osteochondral fragments. Immunologic reactivity is a new concept in equine secondary osteoarthritis and might be involved in the mechanisms of chronic inflammation and progressive collagen destruction in degenerative joint disease.     

Impingement of the dorsal spinous processes in two hundred and fifteen horses: case selection, surgical technique and results

The surgical treatment of impingement of dorsal spinous processes (DSPs) at 2 equine veterinary hospitals following a similar diagnostic and surgical protocol is described with special reference to the diagnosis and case selection. The diagnosis was made from clinical examination and results of radiography and diagnostic analgesia of the affected sites. Scintigraphy was also used as an aid to diagnosis at one hospital. Surgical treatment was generally recommended when conservative treatment, which included 3-9 months rest, intralesional corticosteroids and physiotherapy, had failed. The DSPs were approached through a midline incision in the skin and supraspinous ligament. They were resected using an oscillating saw. Postoperatively, horses were returned to lungeing work after 2 weeks and riding commenced at 3 months, in most cases, and by 6 months in all successful cases. From one to 6 DSPs between thoracic vertebra (T) 11 and lumbar vertebra (L) 3 were resected in individual horses. T15, 16 and 17 were the spines most commonly treated. Long-term follow-up information was obtained in 209 horses. Seventy-two percent of these horses returned to full work and a further 9% improved sufficiently to be used for some athletic work.     

Effects of 0.05% Chlorhexidine Lavage on the Tarsocrural Joints of Horses

In six horses, a 0.05% solution of chlorhexidine diacetate was used to lavage one tarsocrural joint; the contralateral control joint was lavaged with lactated Ringer's solution. Horses were evaluated daily for lameness. Synovial fluid samples were collected on days 1, 4, and 8 for determination of protein concentration, total and differential leukocyte counts, and mucin clot formation. After death on day 8, synovium and osteochondral samples were collected from the tarsocrural joints for examination of morphology and proteoglycan staining. Lavage with chlorhexidine solution caused lameness that was reduced but still evident at day 8. Synovial protein concentration was significantly increased by chlorhexidine lavage; the greatest increase occurred on day 1. Joint lavage increased synovial leukocyte counts on day 1, primarily by increasing polymorphonuclear (PMN) cell counts. Although total synovial leukocyte counts returned to normal by day 4, PMN cell counts remained elevated through day 8; PMN cell counts for chlorhexidine-lavaged joints were typically twice that of control joints. Chlorhexidine lavage caused synovial ulceration, inflammation, and abundant fibrin accumulation. Consistent differences in proteoglycan staining were not detected between control and chlorhexidine-lavaged joints. Joint lavage with 0.05% chlorhexidine diacetate, the lowest known bactericidal concentration, is not recommended for equine joints.     

Factors associated with prognosis for survival and athletic use in foals with septic arthritis: 93 cases (1987-1994).

OBJECTIVE: To identify factors affecting the prognosis for survival and athletic use in foals with septic arthritis. DESIGN: Retrospective study. ANIMALS: 93 foals with septic arthritis. PROCEDURE: Medical records were reviewed to obtain clinical findings, laboratory test results, radiographic findings, treatment method, and outcome. Race records for Thoroughbreds and Standardbreds were evaluated to determine whether foals subsequently raced and whether they raced successfully. RESULTS: 43 foals had 1 affected joint, 44 foals had multiple affected joints, and number of affected joints was not recorded for 6 foals. The femoropatellar and tarsocrural joints were most commonly affected. Osteomyelitis or degenerative joint disease were detected in 59% (46/78) of foals. Failure of passive transfer, pneumonia, and enteritis were common. Foals were treated with lavage, lavage and intra-articular administration of antibiotics, lavage and arthroscopic debridement with or without partial synovectomy, or lavage and arthrotomy to debride infected bone and systemic administration of antibiotics. Seventy-three foals survived to be discharged from hospital, and approximately a third raced. Isolation of Salmonella spp from synovial fluid was associated with an unfavorable prognosis for survival and multisystem disease was associated with an unfavorable prognosis for survival and ability to race; other variables were not significantly associated with survival and ability to race. CONCLUSIONS AND CLINICAL RELEVANCE: With treatment, the prognosis for survival of foals with septic arthritis was favorable, whereas prognosis for ability to race was unfavorable. Multisystem disease, isolation of Salmonella spp from synovial fluid, involvement of multiple joints, and synovial fluid neutrophil count > or = 95% at admission may be of prognostic value.