Pneumothorax in horses: 40 cases (1980-1997)

OBJECTIVE: To characterize pneumothorax in horses and to describe clinical signs, diagnostic testing, and clinical outcome of horses with pneumothorax. DESIGN: Retrospective study. ANIMALS: 40 horses. PROCEDURE: Medical records of horses with pneumothorax were reviewed to obtain information on signalment, history, clinical signs, diagnostic testing, treatment, and clinical outcome. RESULTS: Horses developed pneumothorax secondary to pleuropneumonia (17 horses), open wounds of the thorax (9), closed trauma to the thorax (7), surgery on the upper portion of the respiratory tract (3), and surgery involving the thoracic cavity (1); 3 horses had pneumothorax of unknown cause. Clinical signs included tachypnea, dyspnea, cyanosis, lack of lung sounds on auscultation of the dorsal aspect of the thorax, fever, tachycardia, signs of depression or anxiousness, and cough. Radiography and ultrasonography were useful to definitively diagnose pneumothorax. Pneumothorax was bilateral in 47.5% (19/40) and unilateral in 42.5% (17/40) of horses; designation of unilateral versus bilateral was not recorded in the remaining 4 horses. Horses with pneumothorax secondary to pleuropneumonia more commonly had unilateral pneumothorax (64.7% for unilateral vs 29.4% for bilateral; not specified for 1 horse). Horses with pneumothorax secondary to pleuropneumonia were less likely to survive than horses with pneumothorax secondary to other causes (35.3 vs 69.6% survived, respectively). CONCLUSIONS AND CLINICAL RELEVANCE: Pleuropneumonia is an important cause of pneumothorax in horses. Classic clinical signs of pneumothorax may not be evident. Radiography, ultrasonography, or both may be required for diagnosis. Prognosis for survival is better for horses with pneumothorax not associated with pleuropneumonia.     

Desmitis of the medial tarsal collateral ligament in 7 horses

Severe lameness, tarsocrural joint effusion and medially focused peritarsal swelling combined with focal pain on palpation are clinical signs suggestive of acute injury to the medial tarsal collateral ligament. Diagnosis can be made on physical examination and ultrasonographic findings; however, magnetic resonance imaging may provide more information especially with subtle injury. Acute exacerbation of the injury during the prolonged convalescence is common. The prognosis for medial tarsal collateral ligament desmitis appears good for survival but fair for return to previous levels of performance and requires prolonged periods of rest and a controlled exercise programme.     

Pulmonary aspergillosis in horses: 29 cases (1974-1997)

OBJECTIVE: To analyze medical records and identify factors that veterinarians can use to prevent pulmonary aspergillosis in horses or that would enable them to diagnose it as early as possible. DESIGN: Retrospective study. ANIMALS: 29 horses. PROCEDURE: Medical records were reviewed for horses with pulmonary aspergillosis diagnosed on the basis of characteristic postmortem findings. Information on history, clinical signs, disease progression, and postmortem findings was obtained. RESULTS: 25 of 29 (86.2%) horses had primary (n = 20) or secondary (5) disease compatible with loss of integrity of the gastrointestinal (GI) tract. The remaining 4 horses had a non-GI tract disorder; only 1 of these 4 had clinical signs associated with the respiratory tract (i.e., pleuropneumonia). Although 22 (75.9%) horses had various signs of respiratory tract disorders, an antemortem diagnosis of Aspergillus pneumonia was made in only 1 horse and was suspected in only 1 other. Fungal organisms were seen histologically in tissues other than the lung in 12 (41.4%) horses. CLINICAL IMPLICATIONS: Horses with enteritis, colitis, typhlitis, or other diseases of the GI tract that result in mucosal compromise, and horses with clinical signs of respiratory tract disease, particularly if the horse's condition is unresponsive to treatment with antimicrobial agents; should be considered at high risk of having pulmonary aspergillosis. Immunosuppression from debilitating disease may also predispose horses to aspergillosis. Because invasive pulmonary aspergillosis can be difficult to diagnose, clinicians should be aware of clinical and epidemiologic settings in which this disease would develop.     

Desmitis of the accessory ligament of the deep digital flexor tendon: 27 cases (1986-1990).

Desmitis of the accessory ligament of the deep digital flexor tendon (ALDDFT) was diagnosed in 27 horses between September 1986 and December 1990. The first observed clinical sign in four horses was localised swelling in the proximal metacarpus. Twenty horses became lame suddenly during a work period and most developed swelling within 24 h of exercise. The injury was confirmed by ultrasonographic examination. Ten of 13 horses with uncomplicated desmitis of the ALDDFT resumed full work, within three to nine months of the onset of clinical signs, without recurrence of clinical signs in the period of follow-up (nine months to four years). Three horses presented with concurrent acute desmitis of the ALDDFT and superficial digital flexor (SDF) tendonitis and two horses had a history of SDF tendonitis; none of these resumed full work.     

Outcome of desmoplasty and fasciotomy for desmitis involving the origin of the suspensory ligament in horses: 27 cases (1995-2004)

OBJECTIVE: To determine outcome of percutaneous ultrasound-guided desmoplasty with simultaneous fasciotomy for proximal suspensory desmitis (ie, desmitis of the origin of the suspensory ligament) in horses that have not responded to stall rest. DESIGN: Retrospective case series. ANIMALS: 27 horses. PROCEDURES: Medical records of horses with proximal suspensory desmitis treated by means of desmoplasty with fasciotomy were reviewed. Follow-up information was obtained through telephone conversations with owners and trainers of the horses or by examination of horses at the hospital. RESULTS: 23 of the 27 (85%) horses, including 3 of 4 horses with forelimb lesions and 20 of 23 horses with hind limb lesions, were able to return to full work after surgery and rehabilitation. All horses had ultrasonographic evidence of healing of suspensory ligament lesions. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that desmoplasty with fasciotomy is a viable treatment option in horses with proximal suspensory desmitis that have not responded to stall rest.     

Quadrilateral suspensory and straight sesamoidean ligament calcifying desmopathy in an Arabian mare

A 5‐year‐old Arabian mare was referred for the investigation of recent behavioural change, generalised stiffness, and owner‐reported polyuria and polydipsia. Clinical examination revealed severe pain associated with palpation along the entire length of the suspensory ligament (SL) and palmar soft tissues of the pastern regions of both forelimbs. Radiographs of the distal forelimbs demonstrated marked radiopaque striations within the straight sesamoidean ligaments (SSLs), and less severe but similar changes in the regions of the SL branches. Ultrasonography of both distal forelimbs revealed multifocal, hyperechoic lesions within the SSLs. The SL bodies and branches were enlarged and had mixed echogenicity on ultrasound scan. The horse was subjected to euthanasia at the owner's request and submitted for post‐mortem examination. Relevant gross findings were restricted to the SLs and SSLs of all four limbs, all of which contained severe mineralisation and irregularly arranged fibres. Histological examination revealed severe, multifocal to coalescing, dystrophic mineralisation with cartilaginous and osseous metaplasia, which suggested a primary calcifying desmopathy affecting all four SLs and SSLs. Clinical findings in the case reported here were similar to that of degenerative suspensory ligament desmitis previously reported by many authors, but diagnostic imaging and histopathological findings were significantly different.     

Postoperative infection with Actinobacillus spp in horses: 10 cases (1995-2000)

OBJECTIVE: To determine features of postoperative wound infection caused by Actinobacillus spp in horses undergoing clean, elective surgery and to evaluate bacterial susceptibility profiles of bacteria isolated. DESIGN: Retrospective study. ANIMALS: 10 horses. PROCEDURE: Data were retrieved from medical records and the microbiology laboratory database. RESULTS: 1,604 horses underwent clean, elective surgical procedures during the study period. Of these, 23 (1.43%) had postoperative wound infections, and Actinobacillus spp was isolated from 10 of these 23 (43%). Surgical procedures in these 10 horses included laryngoplasty with ventriculocordectomy (n = 3), arthroscopy (3), desmotomy of the accessory ligament of the superficial digital flexor tendon (2), removal of laryngoplasty prostheses (1), and hygroma resection (1). Seven horses survived, and 3 were euthanatized. All 10 Actinobacillus isolates were resistant to penicillin, and 6 were resistant to trimethoprim-sulfamethoxazole. All isolates were susceptible to ceftiofur and gentamicin. During the 5-year period of the study, Actinobacillus organisms were isolated from 35 of 513 (6.8%) samples from the general hospital population submitted for bacterial culture and antimicrobial susceptibility testing. CONCLUSIONS AND CLINICAL RELEVANCE: During the study period, Actinobacillus spp was isolated from a higher than expected percentage of horses that developed postoperative wound infections after clean, elective surgery. Susceptibility profiles for these isolates were different from typical susceptibility profiles for Actinobacillus isolates, suggesting that a pattern of resistance may be emerging.     

Desmitis of the distal digital annular ligament in seven horses: MRI diagnosis and surgical treatment

Objective— (1) To describe the clinical signs and abnormalities observed on magnetic resonance imaging (MRI) in 7 horses with desmitis of the distal digital annular ligament (DDAL); (2) to describe the normal magnetic resonance (MR) appearance and thickness of the DDAL in health; and (3) to describe a tenoscopic surgical technique for treating horses with desmitis of the DDAL.
Study Design— Retrospective study.
Animals— Horses (n=7) with desmitis of the DDAL.
Methods— MR examinations of 20 sound horses were reviewed to determine the normal appearance of the DDAL. Dimensions obtained from these images were compared with MR findings from 7 horses with DDAL desmitis. Desmitis of the DDAL was treated by tenoscopic surgery and outcome assessed.
Results— Horses with DDAL desmitis had lameness (grade 2–3 out of 5) that improved after a palmar digital nerve block. The affected DDAL was enlarged and had an abnormal signal on MR images of the feet. After tenoscopy and DDAL transection, 5 horses returned to athletic performance, including 2 horses that failed to respond to medical treatment and rest before surgery.
Conclusion— Primary desmitis of the DDAL is a cause of lameness in horses. Transection of the DDAL allowed 5 horses with this injury to return to athletic performance.
Clinical Relevance— DDAL desmitis should be included in the differential diagnoses of horses with lameness that improves after a palmar digital nerve block but have no abnormalities observed on radiographs of the feet. Tenoscopic surgical transection of the DDAL is an effective treatment for some horses.     

Empyema of the guttural pouch (auditory tube diverticulum) in horses: 91 cases (1977-1997)

OBJECTIVE: To identify features of guttural pouch (auditory tube diverticulum) empyema in horses and compare findings of uncomplicated guttural pouch empyema with guttural pouch empyema complicated by chondroids. DESIGN: Retrospective study. ANIMALS: 91 horses with guttural pouch empyema. PROCEDURE: Medical records of horses with guttural pouch empyema were reviewed. RESULTS: The most common owner complaint and abnormal finding was persistent nasal discharge. Chondroids were detected in 21% (19/91) of affected horses. Streptococcus equi was isolated from the guttural pouch in 14 of 44 horses; for Streptococcus spp, in vitro resistance to sulfadimethoxine and trimethoprim-sulfamethoxazole was detected. Retropharyngeal swelling and pharyngeal narrowing were significantly more prevalent in horses with chondroids, compared with horses with uncomplicated empyema. Ninety-three percent of affected horses were discharged from the hospital; at time of discharge, 66% had complete resolution of disease, 19% had improvement without resolution, and 15% did not have improvement. CONCLUSIONS AND CLINICAL RELEVANCE: Horses with persistent nasal discharge should be examined endoscopically for guttural pouch empyema. Treatment with lavage offers a good prognosis for resolution of uncomplicated guttural pouch empyema. Aggressive treatment with lavage and endoscopic snare removal of chondroids offers a good prognosis and may make surgical intervention unnecessary.     

Risk factors for reduced postoperative fecal output in horses: 37 cases (1997-1998)

OBJECTIVE: To determine prevalence and risk factors for development of ileus of the large intestine after surgery in horses, identified by reduced postoperative fecal output (RPFO). DESIGN: Retrospective study. ANIMALS: 37 horses that developed RPFO after undergoing general anesthesia for reasons unrelated to the gastrointestinal tract. PROCEDURE: Fecal output was obtained from medical records as number of defecations per 24-hour period after surgery; RPFO was defined as < or = 3 defecations per 24-hour period after surgery. The reference population included 48 horses that defecated > or = 4 times during the same period. Demographic, clinical, and surgical variables were evaluated for their association with development of RPFO by use of logistic regression analysis. RESULTS: Ten (12%) horses, all of which had RPFO, developed signs of colic after surgery. Horses > or = 5 years old that underwent orthopedic procedures of > 60 minutes' duration and that did not receive phenylbutazone after surgery were at significant risk for developing RPFO. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that after surgery unrelated to the gastrointestinal tract in horses, there is an intermediate clinical phase characterized by reduced fecal output preceding overt signs of colic. Recognition of RPFO may reduce morbidity and mortality of such horses.     

Survival rates for horses undergoing stapled small intestinal anastomosis: 84 cases (1988-1997)

OBJECTIVE: To determine whether location and type of small intestinal anastomosis and other variables were associated with short- and long-term survival rates in horses undergoing stapled small intestinal anastomosis. DESIGN: Retrospective study. ANIMALS: 84 horses that underwent small intestinal anastomosis. PROCEDURE: Medical records from 1988 to 1997 were examined for horses that underwent stapled small intestinal anastomosis. Horses were allotted into 4 groups: jejunojejunostomy (n = 27), jejunoileostomy (11), jejunoileocecostomy with small intestinal resection (20), and jejunoileocecostomy without small intestinal resection (26). Survival rates and other variables were determined. RESULTS: Horses that underwent jejunoileocecostomy without resection had a significantly higher survival rate at all intervals than did horses in the other 3 groups. At 180 and 365 days after surgery, horses that underwent jejunojejunostomy had a significantly lower survival rate than those that underwent jejunoileocecostomy with intestinal resection. Horses that underwent jejunoileocecostomy with intestinal resection had a significantly higher survival rate at 1 year, compared with the combined jejunojejunostomy and jejunoileostomy groups. Preoperative heart rate was inversely associated with survival rate. Overall survival rates at discharge and 1 year were 81 and 56%, respectively. For horses that underwent small intestinal resection, survival rates at discharge and 1 year were 65 and 47%, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Horses that underwent anastomosis of the small intestine to the cecum without resection had the highest survival rate, compared with horses that required intestinal resection. In some instances, resection and anastomosis involving the cecum had better prognosis than resections involving 2 segments of the small intestine.     

Mesenteric rents as a source of small intestinal strangulation in horses: 15 cases (1990-1997)

OBJECTIVE: To describe the clinical findings in horses with small intestinal strangulation through mesenteric rents, and to determine the recurrence and survival rates after surgery. DESIGN: Retrospective study. ANIMALS: 15 horses with small intestinal obstruction via a mesenteric rent. PROCEDURE: Medical records of horses with obstruction of the small intestine via a mesenteric rent between January 1990 and December 1997 were reviewed. The signalment, history, initial physical examination findings, results of abdominocentesis, and clinical laboratory values were recorded. Surgical findings, including location of the mesenteric rent and surgical procedure performed, were recorded. Short- and long-term survival rates were calculated. RESULTS: Most mesenteric rents were located in the mesentery of the small intestine (13 horses). Two horses had multiple mesenteric defects. Seven horses were euthanatized at surgery because of an inability to reduce the entrapped intestine (3 horses), uncontrollable hemorrhage (2), inability to close the rent (1), and the amount of compromised intestine involved (1). Seven horses required intestinal resection and anastomosis. The median length of intestine resected was 2.6 m (range, 0.6 to 4.5 m). The mesenteric rents created during resection were not closed in 2 horses. One of these 2 horses subsequently developed a strangulating obstruction through the open rent. Seven of 15 horses in our study were discharged from the hospital (i.e., short-term survival rate of 47% [7/15]). Long-term follow-up information was available for 5 of the 7 horses (follow-up duration of 5 months to 9 years), of which 2 died as a result of colic, and 1 horse was euthanatized because of severe arthritis (i.e., long-term survival rate of 40% [2/5]). CONCLUSIONS AND CLINICAL RELEVANCE: Inability to reduce the intestinal obstruction, severe hemorrhage from the mesentery, and the length of intestine involved are the main factors that decrease survival rates in horses with small intestinal strangulation caused by mesenteric rents.     

Risk factors for development of acute laminitis in horses during hospitalization: 73 cases (1997-2004)

OBJECTIVE: To identify risk factors for development of acute laminitis in horses during hospitalization for illness or injury. DESIGN: Retrospective case-control study. ANIMALS: 73 horses that developed laminitis (case horses) and 146 horses that did not develop laminitis (control horses) during hospitalization. PROCEDURES: Case and control horses were matched in a 2:1 ratio by the date on which each horse was evaluated. Potential risk factors investigated included age, breed, and sex; highest and lowest values recorded during hospitalization for fibrinogen concentration, WBC count, PCV, and total solids concentration; and comorbid disease states, including pneumonia, endotoxemia, diarrhea, medically treated colic, surgically treated colic, pituitary adenoma, retained placenta or metritis, forelimb lameness, hind limb lameness, acute renal failure, and vascular abnormalities. A univariate screening of all potential risk factors was performed to determine which variables should be selected for further analysis. All factors found to be associated with development of laminitis were included in a multivariate conditional logistic regression model. RESULTS: Development of laminitis was marginally associated with lowest and highest fibrinogen concentrations, highest PCV, and lowest total solids concentration and significantly associated with pneumonia, endotoxemia, diarrhea, abdominal surgery for colic, and vascular abnormalities. In the multivariate analysis, only endotoxemia was significantly associated with laminitis. CONCLUSIONS AND CLINICAL RELEVANCE: Endotoxemia is an important risk factor for development of acute laminitis in horses during hospitalization for medical or surgical conditions. Early recognition of endotoxemia, or the potential for it to develop in certain disease states, and initiation of treatment directed at endotoxemia or its consequences may help prevent laminitis in horses during hospitalization.     

Desmitis of the fetlock annular ligament in the horse

Desmitis of the fetlock annular ligament was diagnosed in 30 horses during a period of eight years. Most of the horses had been lame for a prolonged period and had chronically distended digital flexor tendon sheaths. Air tendograms demonstrated thickened palmar or plantar annular ligaments. In 25 horses the ligament was cut longitudinally; of these, 16 horses returned to full work without any difficulty and one became sound after a second operation. Follow up time varied from three months to seven-and-a-half years. None of the five untreated horses returned to work.     

Medical treatment of cholangiohepatitis and cholelithiasis in mature horses: 9 cases (1991-1998)

The medical approach to treatment of cholangiohepatitis and cholelithiasis in 9 horses is described. Seven horses were treated successfully and returned to normal use, with a minimum follow-up period of 12 months. Long-term antimicrobial therapy was believed to be critical in those cases that survived, with a median treatment duration of 51 days (range 17-124 days). Treatment failure was associated with severe periportal and bridging hepatic fibrosis from biopsy material obtained at admission in 2 horses, one of whom also presented with hyperammonaemic hepatic encephalopathy. Transabdominal ultrasound was used diagnostically in each case to obtain hepatic biopsy material for histopathology and bacterial culture, to evaluate hepatic size and echogenicity and to identify and monitor the dissolution of hepatoliths. Histologically, all horses had evidence of suppurative cholangiohepatitis with varying degrees of periportal and bridging fibrosis. Discrete hyperechoic calculi were identified in 4 cases, but all horses had ultrasonographic evidence of biliary obstruction with numerous dilated bile ducts. Aerobic and anaerobic cultures of liver biopsy material were negative from 7 horses, but 2 different species of Escherichia coli were obtained from one horse, and Bacteroides vulgatus and Escherichia coli were isolated from another. In all 7 horses that survived, clinical recovery was seen before normalisation of biochemical indices of hepatobiliary function including gammaglutamyl transaminopeptidase (GGT), alkaline phosphatase (AP), bile acids and serum bilirubin. Serum GGT levels were monitored extensively as a marker of hepatobiliary disease and actually increased during the initial period of clinical improvement in horses that recovered. Supportive medical therapy with i.v. fluids was also a critical part of the therapy of several cases in this report, both acutely and in the management of chronic cases that deteriorated clinically during treatment. Previous therapeutic failures may well be related to treatment periods of inadequate duration, and the authors recommend that antimicrobial therapy should be continued until GGT values are normal.     

Osteochondral fragments involving the dorsomedial aspect of the proximal interphalangeal joint in young horses: 6 cases (1997-2006)

OBJECTIVE: To determine clinical and diagnostic imaging findings in young horses with osteochondral fragments involving the dorsomedial aspect of the proximal interphalangeal (PIP) joint. DESIGN: Retrospective case series. ANIMALS: 6 horses. PROCEDURES: Medical records were reviewed. Follow-up information was obtained through telephone conversations with owners or trainers or by examining race records. RESULTS: Horses were between 1 and 4 years old. Three had bilateral osteochondral fragments in the forelimbs (n = 2 horses) or hind limbs (1). Radiographically, all but 1 fragment seemed to originate from the dorsomedial aspect of the distal end of the first phalanx. Fragment size ranged from 6 x 9 mm to 11 x 21 mm. Three horses had lameness referable to the region of the affected joint; the other 3 horses did not have clinical signs referable to affected PIP joints. Two horses were euthanized shortly after diagnosis at the owners' request because of concerns that the horses would be unsuited for their intended athletic use. Two of the 3 horses in which fragments were incidental findings were able to race successfully, although 1 received intra-articular corticosteroid treatments; the third was retired because of unrelated orthopedic problems. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that osteochondral fragments involving the dorsomedial aspect of the PIP joint may be an incidental finding in young horses. Given the absence of clinical signs in 5 of 9 affected joints and the fact that 3 of 6 horses were affected bilaterally, a developmental origin of the fragments was suspected.     

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.     

Cholelithiasis in horses: ten cases (1982-1986)

Ten horses with clinical signs consistent with cholelithiasis were evaluated. Fever, icterus, mild intermittent colic, and weight loss were reported. Clinical laboratory abnormalities included leukocytosis, hyper-proteinemia, and hyperfibrinogenemia. Gamma glutamyltransferase and liver isoenzyme of lactate dehydrogenase activities also were high. Choleliths were observed via ultrasonography of the liver in 5 of the 8 horses evaluated, and increased echogenicity of the hepatic parenchyma and dilated bile ducts were observed in all horses. Seven horses were treated medically, 5 of which died or were euthanatized. Three horses were treated surgically, of which only 1 survived. Cholelith composition varied, but cholesterol, calcium bilirubinate, and mixed bile pigments were most commonly observed.