Lymphoma in horses is a type of cancer that originates in the lymphoid tissues, which are part of the immune system. It involves the uncontrolled proliferation of lymphocytes, a type of white blood cell. Lymphoma can affect various organs and systems in horses, including the lymph nodes, spleen, liver, gastrointestinal tract, and skin. Clinical signs may vary depending on the location and extent of the disease, and may include weight loss, lethargy, swelling of lymph nodes, and abnormal blood work. Diagnosis often involves a combination of clinical examination, imaging, and biopsy. This page compiles peer-reviewed research studies and scholarly articles that explore the pathogenesis, diagnosis, treatment options, and prognosis of lymphoma in equine patients.
Nyack B, Padmore CL, Dunn D, Kufuor-Mensan E, Mobini S.A 10-year-old Tennessee Walker gelding, with a history of progressive weight loss, intermittent colic and lethargy, had a slight fever, tachycardia, tachypnea, pallor, ascites and marked ventral edema. Blood analyses revealed anemia, leukocytosis, neutrophilia with a left shift, lymphopenia, monocytosis, hypoproteinemia and a slightly increased SDH level. Abdominocentesis produced red-orange fluid with many RBC and an increased fibrinogen content. Rectal palpation revealed a large mass in the left caudal abdominal quadrant. The animal died shortly after resection of the mass. The histopatholog...
Nyack B, Padmore CL, Dunn D, Kufuor-Mensan E, Mobini S.A 10-year-old Tennessee Walker gelding, with a history of progressive weight loss, intermittent colic and lethargy, had a slight fever, tachycardia, tachypnea, pallor, ascites and marked ventral edema. Blood analyses revealed anemia, leukocytosis, neutrophilia with a left shift, lymphopenia, monocytosis, hypoproteinemia and a slightly increased SDH level. Abdominocentesis produced red-orange fluid with many RBC and an increased fibrinogen content. Rectal palpation revealed a large mass in the left caudal abdominal quadrant. The animal died shortly after resection of the mass. The histopatholog...
Reef VB, Dyson SS, Beech J.Three horses with equine lymphosarcoma were examined because of clinical signs including chronic weight loss, respiratory distress, peripheral edema, and chronic colic. Clinicopathologic findings included evidence of an immune-mediated hemolytic anemia. Immune-mediated thrombocytopenia also was diagnosed in 1 of the horses and suspected in another. One horse died in spite of treatment, 1 died 5 hours after surgical removal of a tumor encircling the jejunum, and 1 was euthanatized because of deteriorating condition. Necropsy of each horse revealed extensive neoplastic infiltration of peripheral...
Perryman LE, Wyatt CR.Equine lymphocytes incubated with Con A and isolated on discontinuous BSA density gradients suppressed mixed lymphocyte reactions in a cell dose- and Con A dose-dependent manner. Suppressor lymphocytes were radiosensitive, even after the initial Con A incubation phase was completed. Suppressor activity was consistently demonstrated using peripheral blood mononuclear leukocytes from normal horses, but was absent in thymus cells and variably present in lymph node cells. Suppressor lymphocytes were present in horses with selective IgM deficiency, and within neoplastic lymph nodes from a horse wit...
Perryman LE, Wyatt CR, Magnuson NS.Neoplastic lymphocytes from a horse with lymphosarcoma and IgM deficiency were analyzed for ability to grow in culture; surface and cytoplasmic IgM; functional activity in blastogenesis, cytoxicity, and suppressor assays; and activities of six enzymes involved in purine and pyrimidine metabolism. The cells lacked surface and cytoplasmic IgM. They had elevated activity of adenosine deaminase and reduced activity of purine nucleoside phosphorylase. Neoplastic cells were nonresponsive in blastogenesis assay and did not kill allogeneic lymphocyte target cells or YAC-1 targets in a lectin-dependent...
Bastianello SS.A survey was carried out on the neoplasms of horses, donkeys and mules which are recorded in the registration files of the Section of Pathology of the Veterinary Research Institute, Onderstepoort, in the Republic of South Africa, over a 40-year period from 1935 to 1974. A total of 378 tumours are recorded, 339 of which were in horses, 32 in mules and 7 in donkeys. Sarcoids (38%), squamous cell carcinomas (23,5%), fibromas (8,2%), melanomas (8,0%), papillomas (4,5%), fibrosarcomas (3,4%) and lymphosarcomas (3,0%) accounted for 88,6% of the total. Of the 58 sarcoids for which the site or origin ...
van den Hoven R, Franken P.This paper describes the clinical and laboratory findings in 16 horses suffering from lymphosarcoma and the autopsy results in 13 of these cases which were examined at the Large Animal Medicine Clinic, State University of Utrecht, from 1969 to 1981. The cases were classified into four groups, designated multicentric, alimentary, thymic and cutaneous forms, according to the situation of the tumours.
Madewell BR, Carlson GP, MacLachlan NJ, Feldman BF.A 17-year-old Arabian gelding was presented because of CNS depression and weight loss. Physical examination revealed generalized lymphadenopathy, pitting edema, and ascites. The diagnosis of lymphosarcoma with leukemic manifestations was based on cytologic and histopathologic examination of lymph node biopsy samples and a peripheral leukocyte count of 98,300/microliters, 94% of which were mature lymphocytes. These circulating lymphocytes lacked B-lymphocyte markers and did not respond to mitogenic stimulation, indicating functional incompetence. Though ultrastructural findings were equivocal, ...
Dixon JB, Jenkins P, Allan D.Culture of murine lymph node cells together with living protoscolices of Echinococcus granulosus is described. The presence of the parasite induced potent blastic transformation in lymphocytes of unimmunized mice as indicated by tritiated thymidine incorporation. The response was markedly reduced by killing the parasite immediately prior to culture. No blastogenic activity was detectable in supernatants from living parasites cultured alone. Protoscolices from artificially infected syngeneic mice were effective stimuli, as were protoscolices from naturally infected horse and sheep. Stimulation ...
Dietz HH.Diagnostic tests in horses showing signs of gastrointestinal diseases are reviewed. The use of rectal exploration is emphasized, and paracentesis as a diagnostic aid is mentioned. Special attention is given to the absorption tests as they are easy to conduct and give a relative measure of the absorptive capability of the intestinal epithelium. Glucose, D(+)-xylose and carbohydrate digestion-absorption tests are compared, and the D(+)-xylose absorption test is preferred because of the univocal curve of absorption (see Figure 1 and 2). The absorption curve in a horse suffering from alimentary ly...
Franken P, van den Hoven R, Sasse HH, Koeman JP, Goedegebuure SD.The case of a three-year-old mare is reported, in which clinical examination revealed the presence of haemorrhagic diathesis as a result of disseminated intravascular coagulation. The animal also showed severe lameness which was due to involvement of the long bones. The diagnosis was only established after death.
Sheahan BJ, Atkins GJ, Russell RJ, O'Connor JP.Two aged mares with histiolymphocytic lymphosarcoma had multiple rapidly proliferating tumours in the subcutis. Consistent haematological changes were absent. One mare had lymph node involvement but no neoplastic lesions in the viscera. Microbiological examination of tumour tissue showed coryneform bacteria; there was no evidence of C-type or lytic viruses or of reverse transcriptase. Prominent intramitochondrial crystalline inclusions were in histiocytic tumour cells.
Rutgers HC, Stibbe S, van den Ingh TS, Breukink HJ.The case of a 16-year-old mare with multiple dermal lymphosarcoma of the histiolymphocytic type is described. Leukaemic changes were not found to be present in the superficial and internal lymph nodes or in the visceral organs.
Roumillat LF, Feorino PM, Lukert PD.Infection of a human lymphoblastoid cell line (Jijoye line derived from a Burkitt lymphoma which contains Epstein-Barr virus) with equine herpesvirus 1, maintained and observed for 53 days, was characterized by the continuous production of infectious extracellular and intracellular virus. Maximum virus production correlated with active cell multiplication. Less than 15% of the cells possessed viral capsid antigen at any one time. Five percent of the cells in the Jijoye line possess Epstein-Barr viral capsid antigen; 80% of the Epstein-Barr viral caspid-containing cells also contained equine he...
Cockerell GL, MacCoy DM.This report provides a general overview of the pathobiology of neoplasia, and an update on the clinicopathological manifestations of lymphosarcoma, mastocytoma, histiocytoma, melanoma, sarcoid and circumanal gland tumors in domestic animals. Neoplasia represents a continuum of events from reversible hyperplasia to irreversible and pathological changes in tissue growth patterns. In some instances the causes of this disease process have been identified, but the etiology of the majority of naturally occurring neoplasms remain unknown. Surgical excision is the preferred treatment for tumors, but i...
Smith BP.Pleural effusion in 37 horses, including 15 acutely affected and 22 chronically affected, was found to be due to a variety of causes, including lymphocarcoma, pulmonary granulomas, coccidioidomycosis, equine infectious anemia, pulmonary abscesses, chronic pneumonia, and primary septic pleural effusion. Age, breed, or sex predilection was not found. Horses with chronic disease had weight loss, increased respiratory rate, dull respiratory sounds in the ventral portion of the thorax, and varying degrees of anorexia. Many horses were anemic. Those acutely affected had respiratory distress or signs...
Roberts MC, Pinsent PJ.Three horses suffering from malabsorption were shown to have alimentary lymphosarcoma predominantly affecting the small intestine and the associated lymph nodes. The diffuse cellular infiltration in two of the case produced marked changes in the villous architecture reducing the available mucosal surface area, and, with lowered or barely detectable disaccharidase activities, contributed to the impairment of digestive-absorptive processes. One of the horses maintained a voracious appetite and was not diarrhoeic, but failed to gain weight, indicating differences in the production and utilisation...
Hawkins KL.Bilateral salpingitis, hydrosalpinx and oophoritis were diagnosed in a mare with concurrent lymphosarcoma. Salpingitis, hydrosalpinx and oophoritis are rare in the mare (1,2,3,5,8,9,11-13). Bilateral salpingitis is an important cause of infertility in all species and is most often due to ascending infection (3-5,10,11). The source of salpingitis in this mare probably was ascending infection from the uterus after parturition. The apparent infertility of the mare was attributed to debilitation from the lymphosarcoma and multiplicity of genital pathoses.
Perry LR, Butler AJ, John E, Martinson S, Buote M, Foote K, Burton S, Stoughton WB.Two equine patients presented separately with severe abdominal distention, colic, lethargy, and decreased appetite. An ante-mortem diagnosis of lymphoma was reached in each case based on peritoneal fluid cytology. Due to a poor prognosis, the horses were humanely euthanized. Post-mortem examination with histology and immunohistochemistry confirmed both cases as lymphoma: alimentary B-cell lymphoma of the distal jejunum and cecum in one case, and T-cell lymphoma of the cecum in the second case. Both cases exhibited extensive metastasis with peritoneal and pleural serosae covered in small nodule...
Rutgers HC, Stibbe S, van den Ingh TS, Breukink HJ.The case of a 16-year-old mare with multiple dermal lymphosarcoma of the histiolymphocytic type is described. Leukaemic changes were not found to be present in the superficial and internal lymph nodes or in the visceral organs.
Lotstra RJ, van den Broek J, Power T, Marr CM, Wijnberg ID.Atrial fibrillation is a common equine arrhythmia. Quinidine alone, or with digoxin are common treatments. Studies on outcome in Warmblood populations in which duration of the AF is often unknown are limited. Objective: To identify the factors that are associated with the success of full treatment cardioversion with oral medication, and establish whether there are differences in these factors between institutions. Methods: Retrospective case series using patient records of Equine University Clinic of Utrecht University and Rossdales Equine Hospital, Newmarket. Methods: Forty-nine horses treate...
Hattori K, Matsuda N, Murakami T, Ito E, Ugawa Y.A 62-year-old man with acute paraplegia was transferred to our hospital. He had flaccid paraplegia and multiple cranial nerve palsies, such as mydriasis of the left pupil, abduction palsy of the left eye, hoarseness and dysphagia, but no meningeal irritation signs. MRI of the spinal canal showed swellings of the conus medullaris and the cauda equine, and also contrast enhancement of the spinal meninges. The cerebrospinal fluid (CSF) showed pleocytosis and protein increment. The lymph node was swollen in his right axilla. The biopsy specimen from the right axillary lymph node revealed metastasi...
Hilbe M, Meier D, Feige K.This article describes an eleven year old mare with apathy, fever, enlarged mandibular lymph nodes, skin lesions on the upper lip and edematous, grey-red mucous membranes in the nose, mouth and vulva. Histopathology revealed infiltrates with atypical lymphocytes forming Pautrier's microabscesses. The neoplastic cells had large, often indented nuclei. Immunohistology showed that some cells were CD3-positive (Pan T-cell-marker). The diagnosis of cutaneous epitheliotropic malignant lymphoma (Mycosis fungoides) was made. The etiology in the horse is unknown.
East LM, Savage CJ.Neoplasia of the equine gastrointestinal tract and abdominal organs occurs predominantly in geriatric horses, although lymphoma and hepatocellular carcinoma and a few other neoplasms can be found in young horses. This article discusses diagnostics that can be used in weight-loss situations, suspicious of neoplasia, as well as tumors themselves including clinical signs, diagnostic tools, histopathologic appearance, and management.
Jaeschke G, Rudolph R.Clinicopathological aspects of equine leukosis are discussed in a review. Among various other findings, only hypercalcaemia accompanied by paraneoplastic syndrome in the course of equine leukosis, increased values of alkaline phosphatase as usual in tumorous diseases, and hypalbuminaemia and hypergammaglobulinaemia in mesentric and intestinal forms of equine leukosis seem to have some diagnostic and pathogenetic significance. Changed values of further parameters are more or less non-specific concomitant signs, indicating that other organs or organ systems have been affected. However, in case o...
Montgomery JB, Duckett WM, Bourque AC.A 6-year-old mare was presented for evaluation of dysuria and pollakiuria. A pelvic mass, which caused obstruction of urinary outflow, was identified. Evidence of renal failure was also present. Due to poor prognosis the mare was euthanized. A postmortem examination revealed a pelvic lymphoma that surrounded and compressed the urethra. Lymphome pelvien comme cause de compression urétrale chez une jument. Une jument âgée de 6 ans est présentée pour évaluation de dysurie et de pollakiurie. Une masse pelvienne qui causait l’obstruction de l’écoulement d’urine a été identifiée. Des...
Scott DW, Walton DK, Smith CA, Lewis RM.Indirect immunofluorescence testing for pemphigus-like antibodies was performed on 79 horses: 28 horses with various nonpemphigus dermatologic diseases, 21 horses with various nondermatologic diseases, and 30 normal horses. Pemphigus-like antibodies were detected in 6 horses: 3 normal horses with titers of 1:40, 2 horses with dermatophilosis at titers of 1:10 and 1:80, and 1 horse with lymphosarcoma at a titer of 1:320. It was concluded that equine pemphigus-like antibodies are a potential source of misinterpretation and misdiagnosis in indirect immunofluorescence testing. Direct immunofluores...
Franken P, van den Hoven R, Sasse HH, Koeman JP, Goedegebuure SD.The case of a three-year-old mare is reported, in which clinical examination revealed the presence of haemorrhagic diathesis as a result of disseminated intravascular coagulation. The animal also showed severe lameness which was due to involvement of the long bones. The diagnosis was only established after death.
Lubczyk B, Nothelfer HB.A case of generalized equine leucosis is presented. The most important clinical signs were cachexia, loss of condition, fever, tachycardia, subcutaneous tumors and severe lameness accompanied by edema of the right thoracic limb. Hematology showed anemia and neutrophilia; clinical biochemistry indicated hypalbuminemia, hyperphosphatemia and hyperfibrinogenemia. Necropsy revealed multiple tumors throughout the body which mainly originated from lymph nodes. Histopathologically the tumors consisted of two cell-types: a. uniform lymphocytoid cells with a highly infiltrative growth pattern; b. heter...
Townsend KS, Johnson PJ, Kuroki K.Primary squamous cell carcinoma of the head and neck occurs in the skin or squamous epithelial lining tissues of the oral cavity, pharynx, larynx, and sinonasal tract. Although it is a common tumor in horses, distant metastatic spread to the lung is rare. This report describes a case of metastatic pulmonary squamous cell carcinoma in a 23-year-old Morgan gelding. The clinical signs displayed by this gelding in some ways mimicked the typical presentation of equine multinodular pulmonary fibrosis or thoracic lymphoma. The postmortem diagnosis in this case was head and neck squamous cell carcinom...
Jaeschke G, Rudolph R.The literature contains about 500 cases of equine leucosis, though the reports are deposited in a great number of journals and vary considerably concerning particular topics. During the last years there has been a remarkable increase of publications about this syndrome in the equine. The clinical leucosis key recommended by us has been confirmed in principle considering the latest literature. In about 70 individual symptoms which can be clinically observed in equine with leucosis 11 can be considered as main symptoms because of their frequency; they are again classified in primary (lymph node ...
Barton CK, Hughes KL, Cowan C, Nout-Lomas YS, Nelson BB.A 21-year-old Quarter Horse mare presented with a chronic, progressively worsening left pelvic limb lameness of 3 weeks duration. The initial examination identified a consistent lameness at a walk. Neurological examination showed sensory and gait abnormalities consistent with left femoral nerve dysfunction. The horse minimally advanced the leg cranially and had a shortened stride length at the walk. During the stance phase, the heels of the left hind foot did not contact the ground and the horse quickly took weight off of the limb. Diagnostic imaging (ultrasound and nuclear scintigraphy) exami...
Kofler J, Kübber-Heiss A, Schilcher F.Clinical, ultrasonographic and pathological findings of a cutaneous, multilocular T-cell lymphosarcoma (malignant lymphoma) in a 13-year-old, brown Austrian warmblood mare are reported. The horse was under clinical observation, and the tumours were sonographically monitored over an 8 month period, revealing worsening of body condition, weight loss, lameness of the left hindlimb and a slight increase in the tumours size. Most of the tumours were covered by normal skin, one showed ulceration. Ultrasonography of the tumours allowed accurate anatomical localization in relation to the adjoining tis...
Potter K, Anez D.A 17-year-old Quarter Horse mare was examined to determine the cause of a vulvar mass. Differential diagnoses for the swollen, ulcerated tissue included hypersensitivity reaction to insect stings or bites and cutaneous neoplasia. During the next 4 months, the mass enlarged involving the skin of the perineum and ventral aspect of the abdomen with secondary dependent edema of both hind limbs. Histologic examination of biopsy and necropsy specimens revealed changes consistent with a diagnosis of mycosis fungoides (cutaneous T-cell lymphoma). Diagnostic features included invasion of neoplastic lym...
Oikawa M, Ohishi H, Katayama Y, Kushiro A, Yoshikawa H, Yoshikawa T.A mass developed in the mandibular gingiva of a thoroughbred racehorse. When the horse could no longer eat unassisted, it was killed and immediately autopsied. Macroscopically, the mandible exhibited extensive osteolysis, with only a small amount of bone remaining around the tooth roots. The cut surface of the mass around the mandible consisted of neoplastic medullary tissue, in which osteogenesis was observed. The medullary tissue was composed of pleomorphic medium-sized to large cells, interlaced by collagen bundles. These cells had large, pale, round or ovoid, sometimes cleaved nuclei, with...
Drbalova J, Musilova P, Kubickova S, Sebestova H, Vahala J, Rubes J.The T cell receptor (TCR) genes (TRA, TRB, TRD and TRG) reside in 3 different chromosomal regions. During the maturation of T lymphocytes, the TCR genes are rearranged by site-specific recombination, a process that also predisposes T cells to aberrant rearrangements. Illegitimate recombination between the TCR genes occurs at a low level in healthy individuals, but this frequency may correlate with the risk of lymphoma. The aim of this work was to investigate interlocus recombination in equids. Illegitimate rearrangements were studied in peripheral blood lymphocytes by FISH with painting and BA...
Torrent A, Kilcoyne I, Johnson A, Affolter VK, Berryhill E, Aleman M.This report describes an unusual presentation of multicentric B-cell lymphoma with central and peripheral nerve involvement in a horse that was presented with acute onset, severe, multiple limb lameness, and muscle atrophy. This case highlights the importance of including neoplasia in the differential list in horses presenting for severe limb lameness associated with muscle atrophy, muscle fasciculations, and weakness. Présentation atypique d’un lymphome à cellules B multisystémique chez un cheval. Ce rapport décrit la présentation inhabituelle d’un lymphome à cellules B multicentriq...
Finley MR, Rebhun WC, Dee A, Langsetmo I.An 8-year-old castrated male Paint Horse was referred because of generalized pruritus, alopecia, and intermittent fever. Results of gross evaluation of the skin and microscopic evaluation of skin scrapings were inconclusive. Histologic examination of skin biopsy specimens revealed vasculitis. The horse had persistent hypercalcemia; therefore, lymphosarcoma was considered a possibility. Ultrasonography revealed hypoechoic nodules within the parenchyma of the spleen and liver. Results of microscopic evaluation of an aspirate from a splenic nodule were suggestive of lymphosarcoma. The condition o...
Hermeyer K, Seehusen F, Gehlen H, Peters M, Wohlsein P.Cutaneous malignant lymphomas are rare in horses and comprise predominantly T-cell-rich B-cell lymphomas. They are characterized by multiple tumour nodules affecting predominantly female horses with a survival rate of months to years. At the final stage, metastases to regional lymph nodes occur, whereas widespread organ involvement is rarely reported. In this case report, a cutaneous T-cell-rich B-cell lymphoma in a 7-year-old standardbred gelding with metastases is described. Clinically, multiple cutaneous and subcutaneous nodules, enlarged superficial lymph nodes, rapid weight loss, and vent...
Lawn K.During training, a 6-year-old standardbred gelding collapsed, exhibiting severe epistaxis and agonal breathing and was euthanized. The horse had a recent history of poor performance, lethargy, and unilateral eyelid swelling with serous ocular discharge. Postmortem and histopathologic examination findings revealed thoracic lymphosarcoma and concurrent exercise-induced pulmonary hemorrhage. Résumé — Mort subite d’un cheval de course de race standardbred causée par un lymphome thoracique. En cours d’entraînement, un standardbred hongre âgé de 6 ans s’est effondré, présentant des s...
Marqués FJ, Hehenberger E, Dickinson R, Wojnarowicz C, Lohmann K.A 9-year-old, 1494-lb (679-kg) Quarter horse gelding in good body condition was admitted to the Veterinary Teaching Hospital, Western College of Veterinary Medicine (WCVM), University of Saskatchewan, for evaluation and treatment of acute respiratory distress. On a trail ride 26 days before presentation, the gelding had been exposed to a horse with clinical signs of an upper respiratory tract infection. The gelding performed well on the trail ride but, 4 days later, developed a mild swelling in the retropharyngeal area and a slight bilateral mucoid nasal discharge. The gelding was examined at ...
Janvier V, Evrard L, Cerri S, Gougnard A, Busoni V.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 ...
Perryman LE, Wyatt CR, Magnuson NS.Neoplastic lymphocytes from a horse with lymphosarcoma and IgM deficiency were analyzed for ability to grow in culture; surface and cytoplasmic IgM; functional activity in blastogenesis, cytoxicity, and suppressor assays; and activities of six enzymes involved in purine and pyrimidine metabolism. The cells lacked surface and cytoplasmic IgM. They had elevated activity of adenosine deaminase and reduced activity of purine nucleoside phosphorylase. Neoplastic cells were nonresponsive in blastogenesis assay and did not kill allogeneic lymphocyte target cells or YAC-1 targets in a lectin-dependent...
