Pathological changes in the navicular bone and associated structures of the horse.

Navicular bones from 74 horses were examined at necropsy. Animals ranged in age from eight months to 30 years. Eight horses had a clinical history of navicular disease. Degenerative lesions in the fibrocartilaginous surface of the navicular bone and of the surface of the deep flexor tendons were age related changes not necessarily related to lameness. These lesions were more extensive in horses with a history of navicular disease, and were often accompanied by adhesions and subchondral cavitation of the fibrocartilaginous surface of the navicular bone. Osteophytes, present in 12 of the 74 horses, appeared to be age-related and were uncommon in horses with a history of navicular disease. Nutrient foramina on the distal border of the navicular bone were highly variable in size and shape; in horses with a history of navicular disease they often had a small external opening that became larger as it penetrated the bone. Occlusive vascular disease (arteriosclerosis) was found in sound horses and in horses with a history of navicular disease. Thrombosis of arteries or ischemic necrosis of bone was not identified in any case.     

Surgical Treatment of Colic Results in 181 Horses

A retrospective study was performed of 181 horses that underwent an exploratory celiotomy because of acute abdominal disease. Forty-four horses died or were euthanized during surgery. Of the 137 horses that recovered from anesthesia, 72 died of associated diseases or complications, 86 were discharged from the hospital of which 60 survived at least 7 months. Horses with disorders affecting the small intestine had a significantly lower survival rate. Causes of death early in the postoperative period included long bone fracture, shock, ileus, gastric rupture, and peritonitis. After discharge from the hospital, deaths were attributed to colic of unknown cause, malabsorption syndrome, adhesive small bowel obstruction, small and large intestinal volvulus, perforated bowel, and laminitis. Of the 60 horses that were alive at the time of survey, 93.3% had returned to their previous use. A second occurrence of the initial acute abdominal disease was not documented in any horse.     

The Effect of Hay Net Design on Rate of Forage Consumption When Feeding Adult Horses

Modern horse management systems tend to limit a horse's opportunity to forage. The objective of this experiment was to investigate the effect of hay net design on the rate of forage consumption when feeding horses. Eight adult horses were fed in individual stalls in a replicated Latin square design, with two horses per treatment per week. Horses were fed hay off the stall floor (control), or from one of three hay nets: large (15.2 cm openings), medium (4.4 cm openings), and small (3.2 cm openings). Horses had access to hay for two 4-hour periods each day. When horses could not consume all forage from the medium and small hay nets in 4 hours, a second study using a crossover design gave horses an unlimited amount of time to feed from the hay nets. Stopwatches were used to calculate time to consumption and dry matter intake rates (DMIR). Mean time to consumption was 3.1 and 3.4 hours for the control and large hay net, respectively, in study 1, and 5.1 and 6.5 hours for the medium and small hay nets, respectively, in study 2. Mean DMIR during the 4-hour feeding period were 1.5, 1.3, 1.1, and 0.9 kg/hr for the control, large, medium, and small hay nets, respectively; all treatments were different (P < .0001). These results demonstrate that hay nets were effective at decreasing the rate of forage consumption when feeding adult horses. Long-term studies are warranted to determine if horses will adapt to feeding from hay nets.     

Preliminary study on the effects of pergolide on left ventricular function in the horses with pituitary pars intermedia dysfunction

BackgroundPituitary pars intermedia dysfunction (PPID), a neurodegenerative disease leading to reduced dopamine production, is a common disease in aged horses. The treatment is based on administration of the dopamine agonist pergolide. This drug has been related to valvular fibrosis in humans, but the cardiovascular effect of this drug has not yet been investigated in horses.ObjectivesTo determine whether pergolide induces valvular disease in horses or affects the cardiac function.MethodsStandard, tissue Doppler (TDE) and two-dimensional speckle tracking (STE) echocardiography were performed in horses with diagnosed PPID based on adrenocorticotropic hormone dosage. Measurements taken in horses treated with pergolide were compared with those from untreated horses with nonparametric t-tests. Furthermore, measurements from follow-up examinations performed at least three months after the initial exam were compared with a Wilcoxon signed rank test for repeated measurements in each group.ResultsTwenty-three horses were included. None of the 12 horses under treatment developed valvular regurgitation. Furthermore, no differences in the measurements of the left ventricular systolic or diastolic function could be seen between the group of horses with treatment and those without treatment. Measurements taken in the follow-up exam did not differ compared to those taken in the initial exam in both groups.ConclusionsNo changes of the left ventricular function assessed by TDE and STE could be shown in a small population of horses with confirmed PPID. Treatment with pergolide did not affect the ventricular function nor induce valvular disease.     

Detection of apoptotic cells in intestines from horses with and without gastrointestinal tract disease

OBJECTIVE: To identify apoptosis in equine intestines and determine whether apoptosis is associated with gastrointestinal tract disease or a specific tissue layer of intestine. ANIMALS: 38 horses that underwent surgery or were euthanatized for small or large intestine obstruction, strangulation, or distension and 9 control horses euthanatized for reasons other than gastrointestinal tract disease or systemic disease. PROCEDURE: Specimens were collected at surgery from intestine involved in the primary lesion and distant to the primary lesion site or at necropsy from several sites including the primary lesion site. Histologic tissue sections were stained with H&E, and apoptosis was detected by use of the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling technique. The number of apoptotic cells per hpf was counted in the mucosa, circular muscle, longitudinal muscle, and serosa. RESULTS: Apoptotic nuclei were seen in all layers of intestine. An increased number of apoptotic cells was found in the circular muscle of the intestine from horses with simple obstruction, compared with strangulating obstruction or healthy intestine. Intestine distant from a primary strangulating lesion had higher numbers of apoptotic cells than did intestine distant from a simple obstructive lesion or intestine taken at the site of a strangulating or simple obstructive lesion. CONCLUSIONS AND CLINICAL RELEVANCE: Intestine from horses with obstructing or strangulating lesions in the small intestine and large colon had high numbers of apoptotic cells possibly because of ischemic cell injury and subsequent inflammation. Whether substantial apoptosis affects intestinal function is not yet known.     

Pulmonary dysfunction and skeletal muscle changes in horses with RAO

BACKGROUND: Chronic pulmonary diseases (recurrent airway obstruction [RAO]) have been reported to alter skeletal muscle cells in humans. The purpose of this study was to evaluate a potential relationship between pulmonary and muscle variables in horses with a clinical diagnosis of RAO. Muscle biopsies from healthy horses and from horses with RAO were investigated and the relationship between the severity of lung disease and the degree of muscular changes was determined. HYPOTHESIS: We hypothesized that chronic pulmonary disease can lead to changes of the skeletal muscle in horses. ANIMALS: Fifteen healthy horses (control) and 50 horses with RAO were examined. METHODS: In a prospective clinical trial, a complete lung examination was performed in all horses. In all horses, muscle enzyme activity at rest and after exercise and muscle biopsies from the M. gluteus medius were examined. RESULTS: None of the horses had clinical or histologic signs of primary or neurogenic myopathies. According to the clinical, endoscopic, and radiographic findings and with a scoring system, the horses with RAO were grouped according to the severity of pulmonary findings (15 horses mild, 24 horses moderate, 11 horses severe RAO). Pathologic changes of the skeletal muscle (fiber atrophy or fiber hypertrophy, myofibrillar degeneration, hyperplasia of mitochondria, and ragged-red-like fibers) were identified in most horses with RAO but in only a few individual control horses. In addition, a marked depletion of muscle glycogen storage was evident in the RAO horses but not in the control group. Other pathologic changes of skeletal muscle such as centralized nuclei and regenerating fibers were rare, but were more frequent in horses with lung diseases than in the control group. The degree of muscle cell changes was also graded with a scoring system and correlated with the severity of pulmonary disease (r= 0.55). CONCLUSION: Chronic pulmonary disease in horses is associated with structural changes in skeletal muscle. CLINICAL IMPORTANCE: Because chronic pulmonary disease may affect muscles, early and effective therapy may prevent these changes. This finding could be of clinical importance but requires further studies.     

Chronic small airway disease in the horse: immunohistochemical evaluation of lungs with mild, moderate and severe lesions

The peroxidase anti-peroxidase technique was used to demonstrate free and intracellular immunoglobulin (Ig) within the lungs of 23 horses with chronic small airway disease. Histologically, all the horses had chronic bronchiolitis; however, the lesions varied in degree from mild in eight horses, to moderate in nine horses and severe in six horses. Lungs from three horses which had no gross or histopathological lesions were used as controls. In comparison with control horses, horses with mild chronic bronchiolitis had increased numbers of Ig A-containing and non-immunoglobulin staining cells around the vasculature and bronchioles. As the severity of the lesions increased so did the number of IgA-, IgG(Fc)- and in several cases non-immunoglobulin staining cells around the vasculature, bronchioles and in the alveolar septa. In severely affected horses, large amounts of free IgG(Fc) were observed interstitially and in alveoli. In areas of mucosal epithelial hyperplasia and metaplasia large amounts of free IgA and IgG(Fc) were sometimes observed interepithelially in a pattern which differed from that in control horses.     

Fibrin/fibrinogen in lungs and respiratory secretions of horses with chronic pulmonary disease

The concentration of soluble fibrinogen derivatives (SFD) and protease and procoagulant activities were determined in cell-free supernatants of equine respiratory secretions obtained from horses with chronic pulmonary disease. The concentration of neutrophils was estimated from direct smears of the secretions. Lung specimens and smears of the secretions were evaluated for the presence of fibrin or fibrinogen by use of immunohistochemical methods. Thirty-five of 80 specimens tested contained SFD. Respiratory secretions from horses with moderate or severe chronic pulmonary disease contained SFD more frequently than did secretions from mildly affected horses (P less than 0.05). Respiratory secretions with vast numbers of neutrophils had significantly (P less than 0.05) higher SFD concentrations than respiratory secretions with fewer neutrophils. Protease and procoagulant activities in respiratory secretion specimens were positively correlated with neutrophil content, clinical diagnosis, and SFD concentration. Immunohistochemically, macrophages that stained for fibrin or fibrinogen were observed in direct smears of respiratory secretions from horses with moderate and severe chronic small airway disease, but not in smears from mildly affected horses. Fibrin or fibrinogen was detected in a few thickened alveolar septa from 10 horses with moderate or severe chronic small airway disease, but not in lungs from horses with mild or no evidence of chronic small airway disease. Fibrin or fibrinogen was detected in alveolar septa, granulomas, and on alveolar macrophages in lungs of all horses with chronic granulomatous and chronic bronchointerstitial pneumonia. The presence of SFD in equine respiratory secretions may be an indicator of pulmonary inflammation.     

Haematological measurements as an aid to early diagnosis and prognosis of respiratory viral infections in thoroughbred horses

In late November 1988 large numbers of thoroughbred horses in training in Hong Kong developed a transient pyrexia with, in some cases, the clinical signs of viral respiratory disease. Serial blood samples for haematological examination were taken from 10 of the horses which were stabled in six different blocks. They had developed a high temperature within three days of each other and subsequently seroconverted to equine herpes virus 1 (EHV1). The absolute monocyte count was more than 0.5 x 10(9)/litre in all 10 within the first five days, and nine of them had a high neutrophil/lymphocyte ratio on the first day, which then decreased and reversed within four or five days. Five of the horses had a high plasma viscosity, and a large difference between the viscosity of plasma and serum which in three of them returned to normal within 10 days. In the two and a half months after the initial infection six of nine of the horses, including the five which had a large difference between the viscosity of plasma and serum, developed visible mucopus by endoscopic examination. These haematological and endoscopic changes can be used to detect horses in the acute stages of EHV1 infection and monitor the progress of the disease, before it can be confirmed by isolation of the virus and, or, serology.     

Effect of Omentectomy on Adhesion Formation in Horses

Objective —To determine if omentectomy would decrease the frequency of postoperative intraabdominal adhesions. Study Design —Retrospective study. Animals or Sample Population—44 horses that had either two ventral median celiotomies or a ventral median celiotomy and a necropsy more than 4 days later; 19 of these horses had their omentum removed at the initial surgery. Methods —Data retrieved from the records included location and type of intraabdominal adhesions; location of the surgical lesion; relationship of adhesions to the surgical lesion; surgical procedures; duration of initial surgery; time interval between procedures; age, gender, and breed of the horse; and clinical outcome. Fisher's exact test was used to evaluate the association between categorical explanatory and outcome variables. The effect of potential risk factors on the incidence rate of adhesion formation was estimated using a proportional hazards regression model. Results —Of 25 horses in the nonomentectomy group, 15 (60%) had postoperative adhesions that resulted in the need for a second surgical intervention, whereas of 19 horses that had omentectomy initially, only 4 (21%) had postoperative adhesions that required a second procedure. Rate of adhesion formation was higher in horses that did not have omentectomy initially (incidence ratio rate [IRR], 0.46; 90% confidence interval [CI], 0.18 to 1.19). At initial surgery, 24 horses had a small intestinal lesion, and 20 horses had a large intestinal lesion. Fifteen horses (63%) with small intestinal lesions subsequently developed adhesions compared with four horses (20%) with an initial large intestinal lesion (P= .006). At the second procedure, small intestine lesions were identified in 32 horses and large intestine lesions in 12 horses (1 horse had both small and large intestine lesions), and 1 horse had a gastric lesion. Adhesions were identified as the cause of colic signs in 19 (61%) horses with small intestinal lesions and in none of the horses with large intestine lesions. The frequency of adhesion development leading to colic associated with only the small intestine at the second surgery or necropsy was significantly greater (P= .001) than the frequency only in the large intestine. Conclusions —Omentectomy reduced the rate of postoperative adhesion formation. Adhesions are more likely to occur after small intestinal surgery and if they do occur likely involve the small intestine. Clinical Relevance —Omentectomy is a safe procedure and should be considered prophylactically for reduction of adhesion formation after abdominal surgery in horses.     

Sudden death attributable to exercise-induced pulmonary hemorrhage in racehorses: nine cases (1981-1983)

Pathologic changes are described in 11 horses that died during racing or training; 9 died of acute pulmonary hemorrhage (exercise-induced pulmonary hemorrhage), 1 died of exsanguination, and 1 died of CNS trauma. Cardiac lesions were not found in any horse. Severe engorgement of pulmonary vessels, with hemorrhage into alveoli, airways, interstitium, and subpleural tissues, was observed in all 9 horses that died of exercise-induced pulmonary hemorrhage. Infiltration of eosinophils and/or lymphocytes around vessels and airways was seen in 6 horses. Focally extensive fibrosis was observed in the pleura and interstitium of 6 horses, and collections of siderophages were seen in the fibrous tissue and in the airways. Focal occlusion of bronchioles with inspissated mucus, such as that associated with small airway disease, was found in 4 horses. Underlying respiratory tract lesions, particularly those associated with small airway disease or bronchiolitis, may have a role in fatal pulmonary hemorrhage.     

Transmission studies of Hendra virus (equine morbilli-virus) in fruit bats, horses and cats

Objective To determine the infectivity and transmissibility of Hendra virus (HeV). Design A disease transmission study using fruit bats, horses and cats. Procedure Eight grey-headed fruit bats (Pteropus poliocephalus) were inoculated and housed in contact with three uninfected bats and two uninfected horses. In a second exper iment, four horses were inoculated by subcutaneous injection and intranasal inoculation and housed in contact with three uninfected horses and six uninfected cats. In a third experi ment, 12 cats were inoculated and housed in contact with three uninfected horses. Two surviving horses were inoculated at the conclusion of the third experiment: the first orally and the second by nasal swabbing. All animals were necropsied and examined by gross and microscopic pathological methods, immunoperoxidase to detect viral antigen in formalin-fixed tissues, virus isolation was attempted on tissues and SNT and ELISA methods were used to detect HeV-specific antibody. Results Clinical disease was not observed in the fruit bats, although six of eight inoculated bats developed antibody against HeV, and two of six developed vascular lesions which contained viral antigen. The in-contact bats and horses did not seroconvert. Three of four horses that were inoculated devel oped acute disease, but in-contact horses and cats were not infected. In the third experiment, one of three in-contact horses contracted disease. At the time of necropsy, high titres of HeV were detected in the kidneys of six acutely infected horses, in the urine of four horses and the mouth of two, but not in the nasal cavities or tracheas. Conclusions Grey-headed fruit bats seroconvert and develop subclinical disease when inoculated with HeV. Horses can be infected by oronasal routes and can excrete HeV in urine and saliva. It is possible to transmit HeV from cats to horses. Transmission from P poliocephalus t o horses could not be proven and neither could transmission from horses to horses or horses to cats. Under the experimental conditions of the study the virus is not highly contagious.     

Comparison of bronchoalveolar lavage and respiratory secretion cytology in horses with histologically diagnosed pulmonary disease

Equine bronchoalveolar lavage (BAL) fluid collected from 70 horses and respiratory secretions (RS) obtained from 61 of these horses were evaluated cytologically and grouped according to the histological diagnosis of the lungs from which they were obtained. The histological categories included: normal lung (8 horses); pulmonary eosinophilic infiltration (9 horses); interstitial pneumonia (5 horses); pulmonary hemorrhage (5 horses); and mild (12 horses), moderate (7 horses) and severe (24 horses) chronic small airway disease. In horses with pulmonary disease, all BAL samples and all but one RS sample differed cytologically to those obtained from normal horses; however, the type and severity of the pulmonary disease could not always be determined using either BAL or RS cytology. There was a positive association between the percentage of neutrophils in BAL and the neutrophil scores in RS specimens; there was no positive association between other cell types.     

Arthroscopic Surgery for the Treatment of Osteochondrosis in the Equine Shoulder Joint

Osteochondritis dissecans (OCD) and subchondral cyst-like lesions in 13 shoulders of 11 horses were treated arthroscopically by curettage and lavage. Lameness decreased in all 11 horses. Nine horses were sound, five of them athletically sound, after 5 to 20 months. Complications included the development of subchondral cyst-like lesions and signs of degenerative joint disease. Arthroscopic surgery of the equine shoulder can be done through two portals, one for the arthroscope and one for an instrument. A few hand instruments such as a probe, Ferris-Smith rongeurs, and small, large, and right-angled curettes are needed to debride most lesions. Motorized equipment can expedite the process.     

Pedunculated lipomas as a cause of intestinal obstruction in horses: 17 cases (1983-1990).

The medical records of 17 horses that were evaluated and treated because of colic caused by pedunculated lipomas between 1983 and 1990 were reviewed. The mean age of the horses was 16.6 +/- 3.9 years (range, 10 to 26 years), which was significantly greater than that of the population of horses evaluated because of colic (control population) during the same period. There were significantly more geldings (76.5%), compared with the control population. Nasogastric reflux ranged from 1 to 16 L in 8 horses and was not obtained in 9 horses. Abdominal palpation per rectum revealed small intestinal distention in 13 horses, displaced large colon in 7 horses, and large colon impaction in 2 horses. Peritoneal fluid was abnormal in 11 of 12 horses from which it was obtained successfully. One horse was euthanatized after unsuccessful medical treatment. Surgery was performed in 16 horses. Lipomas were blindly resected in 5 horses or exteriorized and resected in 6 horses. The method used to resect the lipoma was not recorded in 5 horses. The ileum and/or jejunum was strangulated in 15 horses, the small colon was strangulated in 1 horse, and the jejunum was obstructed in 1 horse. The length of intestine resected ranged from 0.15 to 7.2 m. Fourteen horses survived surgery, of which 11 were discharged from the hospital (short-term survival rate of 78.6%). Excluding 2 horses lost to follow-up evaluation, 6 of 12 horses that survived surgery were alive 2 to 56 months following surgery (long-term survival rate of 50%), and 9 of 15 horses died or were euthanatized (fatality rate of 60%).     

Ultrastructural findings in horses with chronic obstructive pulmonary disease (COPD). I: Alterations of the larger conducting airways

Extensive light and electron microscope studies of the conducting airways were carried out in 28 horses with varying degrees of clinically manifested chronic obstructive pulmonary disease (COPD) and in 8 horses with normal lungs. The principal ultrastructural changes were found in the ciliated cells. There was focal loss of ciliated cells, which were replaced by undifferentiated cells in a largely hyperplastic epithelium, and some horses, independent of the degree of severity of the disease, showed various types of ciliary malformation. The finding of dilated intercellular clefts and accumulations of mast cells was interpreted as morphological evidence of non-specific mucosal hyperreactivity. Interstitial cells with intracytoplasmal crystal inclusions, the cause of which is not clear, were seen in many horses. Comparison between the clinical diagnosis and the morphological findings showed partial correlation. The ciliary loss, the appearance of peribronchial inflammatory processes and the occurrence of intracytoplasmic crystalline inclusions showed a positive correlation. In 12 of 28 cases, the severity of clinical diagnosis agreed with the degree of the morphological findings. The changes in the conducting airways were interpreted pathogenetically as reactive processes to changes in the small airways in the course of equine COPD.     

Extension large colon resection in 12 horses

Extensive resection (50-75%) of the large colon was performed in 12 horses. Indications for resection were: loss of viability due to large colon volvulus (seven), thromboembolic episode (three), impairment of flow of ingesta due to adhesions (one), or congenital abnormalities (one). The time required to correct the primary cause of abdominal pain and complete the resection ranged from 2.5 to 4.75 hours. Three horses had severe musculoskeletal problems postoperatively and were euthanized in the recovery stall. Four other horses were euthanized early in the postoperative period because of: further large colon infarction (two), ileus (one), or small intestinal problems (one). Five horses survived with no apparent nutritional or metabolic problems during two to three weeks of hospitalization. Clinical data were obtained from these horses from nine months to eighteen months postoperatively and revealed no clinical or clinicopathological abnormalities in four of them; the fifth horse exhibited diarrhea and weight loss four months postoperatively but responded to diet change.     

Analysis of Sodium Carboxymethylcellulose Administration and Related Factors Associated with Postoperative Colic and Survival in Horses with Small Intestinal Disease

Objective— To analyze the effect of the intraoperative use of sodium carboxymethylcellulose (CBMC) and related perioperative factors on postoperative colic and survival in horses that had abdominal surgery for colic.
Study Design— Retrospective study.
Animals— Horses (n=203) that had surgery for small intestinal disease; 33 horses had intraoperative administration of CBMC.
Methods— Information was obtained from medical records for 170 horses that had surgery for colic before use of CBMC and 33 horses that had intraoperative CBMC. Kaplan–Meier survival curves were used to estimate median survival time and a Cox proportional hazards model was used to estimate the hazard ratio for the effect of CBMC and other perioperative variables on survival.
Results— Seventy-five percent of horses administered CBMC survived to 180 days, whereas 75% of untreated horses survived 8 days (median survival time=18 days). Horses not administered CBMC were twice as likely to die compared with horses administered CBMC. Horses that had postoperative ileus (POI) were 1.4 times more likely to die than horses without ileus. Similarly, horses with signs of colic after surgery were 1.3 times more likely to die than horses without postoperative signs of colic.
Conclusions— CBMC administration is seemingly protective against death and prolongs survival when used intraoperatively in horses with small intestine disease, particularly horses with postoperative colic or POI. Both POI and colic increased risk of death after surgery.
Clinical Relevance— Intraoperative administration of CBMC in horses that have surgery for small intestinal disease may improve survival, possibly by reducing early adhesion formation.     

Effect of standing tarsal angle on joint kinematics and kinetics

REASONS FOR PERFORMING STUDY: The tarsal joint is a frequent site of lameness, but little objective information is available regarding the effects of tarsal conformation on joint movements or forces. OBJECTIVE: To compare tarsal kinematics and kinetics in horses with large, intermediate and small tarsal angles. METHODS: Sagittal plane standing angle of the right tarsal joint was measured in 16 horses as they stood squarely with the hind hooves vertically beneath the hip joint. Tarsal angles were classified as small (< 155.5 degrees), intermediate (155.5-165.5 degrees) or large (> 165.5 degrees). Reflective markers, attached over the centres of joint rotation, were tracked during stance as the horses trotted across a force plate at a standardised speed. Joint angles and ground reaction forces were combined with morphometric data to calculate net joint moments and net joint powers across the tarsus using inverse dynamics. RESULTS: In all horses, the tarsus flexed during the impact phase and extended in late stance. Tarsal angles were stratified according to standing tarsal angle throughout stance. Horses with large standing angles showed less flexion and less energy absorption at the tarsus during the impact phase than those with intermediate or small angles and generated less vertical impulse than horses with small standing angles. Net extensor moment at the tarsus during stance was lower for horses with large standing angles. CONCLUSIONS: In horses with large tarsal angles, less concussion was absorbed during the impact phase, which may be a factor in the development of degenerative joint disease; and the smaller vertical impulse and extensor moment later in stance may limit propulsive ability. However, the smaller net joint moment may reduce the risk of plantar ligament desmitis. CLINICAL SIGNIFICANCE: The effects of conformation on kinematics and kinetics of the tarsal joint may influence both performance and soundness.     

ULTRASONOGRAPHIC FINDINGS IN 13 HORSES WITH LYMPHOMA

Ultrasonography and radiography are commonly used for staging of lymphoma in horses, however there is little published information on imaging characteristics for horses with confirmed disease. The purpose of this retrospective, case series study was to describe ultrasonographic and radiographic findings for a group of horses with a confirmed diagnosis of lymphoma. A total of 13 horses were sampled. Lymphadenopathy (8/13), peritoneal effusion (6/13), splenic (6/13), and hepatic (5/13) lesions were the most frequently identified. The predominant splenic and hepatic ultrasonographic lesions were hypoechoic nodules, organomegaly, and changes in echogenicity. Digestive tract lesions were detected in three horses and these included focal thickening and decreased echogenicity of the small (2/13) and large intestinal (2/13) wall. Thoracic lesions were predominantly pleural effusion (4/13), lymphadenopathy (4/13), and lung parenchymal changes (3/13). Enlarged lymph nodes were detected radiographically (4/13) and/or ultrasonographically (2/13) in the thorax and ultrasonographically in the abdomen (7/13) and in the caudal cervical region (4/13). Findings supported the use of abdominal and thoracic ultrasonography for lymphoma staging in horses. Ultrasound landmarks for localizing cecal and caudal deep cervical lymph nodes were also provided.