Lymphonodi mesenterici
The mesenteric lymph nodes include the cranial mesenteric nodes (draining the small intestine and large colon), caudal mesenteric nodes (draining the small colon and rectum), and cecal nodes. They filter lymph from the gastrointestinal tract and contain abundant lymphoid tissue. They are the primary immunological surveillance system for the gut. Enlargement can occur with infection or neoplasia.
These nodes are not directly accessible but can be assessed by rectal palpation of the mesenteric root, transabdominal ultrasound, and abdominocentesis. Markedly enlarged nodes palpable per rectum can suggest lymphosarcoma or metastatic (bastard) strangles. Normal mesenteric nodes are not individually palpable. Peritoneal fluid analysis may show neoplastic lymphocytes or inflammatory cells depending on the disease.
## Overview Bastard strangles, also called metastatic strangles, is a serious complication of infection with Streptococcus equi equi (the bacterium that causes classic strangles). In ordinary strangl
## Overview Alimentary lymphosarcoma (also called alimentary lymphoma) is a malignant neoplasm of lymphocytes that primarily affects the gastrointestinal tract. It is the most common intestinal tumor
## Overview The abdominal form of Rhodococcus equi infection in foals involves abscessation of mesenteric lymph nodes and ulcerative enterocolitis, in addition to or instead of the classic lung absce
Chronic granulomatous inflammation of the intestinal wall and mesenteric lymph nodes. May be associated with Mycobacterium avium subsp. paratuberculosis (though true Johne's disease is very rare in ho
Unexplained weight loss, fever, or abdominal discomfort with other systemic signs should be evaluated. The veterinarian may assess the mesenteric root during a rectal examination.
## Overview Bastard strangles, also called metastatic strangles, is a serious complication of infection with Streptococcus equi equi (the bacterium that causes classic strangles). In ordinary strangles the bacteria stay in the lymph nodes of the head and neck and form abscesses there. In bastard strangles the bacteria spread through the blood or lymphatics and form abscesses in distant sites such as the abdomen, thorax, or other lymph nodes. This form raises the risk of death substantially compared with uncomplicated strangles. ## Causes The primary cause is infection with Streptococcus equi equi. Metastatic spread occurs when the bacteria escape the regional lymph nodes. Factors that may increase the chance of metastasis include severe or prolonged infection, incomplete immunity, and possibly certain bacterial strains, although the evidence is limited on host or bacterial predictors. ## Diagnosis Horses with bastard strangles often show non-specific signs such as intermittent fever, weight loss, colic, or respiratory difficulty rather than the classic swollen head lymph nodes. Ultrasound or radiography can locate internal abscesses. Culture or polymerase chain reaction testing of abscess material or nasal washes confirms the organism. Bloodwork commonly shows chronic inflammation. ## Treatment Unlike many uncomplicated strangles cases, bastard strangles usually requires prolonged antimicrobial therapy (commonly procaine penicillin) plus intensive supportive care. Drainage of accessible abscesses and treatment of secondary problems such as colic or pneumonia are important. Isolation and biosecurity measures remain essential because the horse can still shed bacteria. ## Recovery and Prognosis Prognosis is guarded to poor. Mortality rises markedly once metastatic abscesses develop. Survivors may need weeks to months of treatment and can have lasting organ damage. Some horses become long-term carriers in the guttural pouches even after clinical recovery. ## Prevention Prompt isolation of new or febrile horses, good hygiene, and appropriate use of vaccination where indicated reduce the incidence of strangles outbreaks and therefore the chance of metastatic disease. Early veterinary attention to classic strangles cases may limit spread within the body. Signs include: intermittent fever; chronic weight loss; colic or abdominal pain; respiratory difficulty; depression; internal abscesses on imaging
## Overview Alimentary lymphosarcoma (also called alimentary lymphoma) is a malignant neoplasm of lymphocytes that primarily affects the gastrointestinal tract. It is the most common intestinal tumor in horses and tends to occur in middle-aged to older animals. Lesions may be focal, segmental, or diffuse within the intestinal wall, most often involving the small intestine. Clinical signs result from malabsorption, protein-losing enteropathy, partial obstruction, or secondary complications such as ulceration or perforation. ## Causes The cause is unknown. No consistent viral or environmental trigger has been identified in horses. The disease may arise de novo in gut-associated lymphoid tissue or represent a component of multicentric lymphoma. ## Diagnosis Chronic weight loss, intermittent colic, diarrhea, or hypoalbuminemia raise suspicion. Rectal examination may reveal thickened intestine or enlarged mesenteric lymph nodes. Abdominal ultrasound often shows thickened intestinal walls or masses. Peritoneal fluid cytology or intestinal biopsy (via laparoscopy or exploratory surgery) provides definitive diagnosis. Differentiation from inflammatory bowel disease can be challenging without histopathology. ## Treatment There is no curative treatment. Corticosteroids (prednisolone or dexamethasone) may produce temporary improvement in appetite and clinical signs, particularly with T-cell forms. Surgical resection is occasionally possible for solitary, accessible masses without regional metastasis, but most cases are multifocal or diffuse. Supportive care addresses secondary complications. ## Recovery and Prognosis Prognosis is poor to grave. Survival is typically measured in weeks to a few months after diagnosis, although occasional horses experience longer temporary remissions with corticosteroid therapy. Euthanasia is often elected when quality of life declines. ## Prevention No preventive measures are known. Signs include: chronic weight loss; intermittent colic; diarrhea or soft feces; ventral edema; poor appetite; thickened intestine or masses on rectal or ultrasound examination
## Overview The abdominal form of Rhodococcus equi infection in foals involves abscessation of mesenteric lymph nodes and ulcerative enterocolitis, in addition to or instead of the classic lung abscesses. Foals 1 to 6 months old show chronic diarrhea, weight loss, a pot-bellied appearance, and abdominal lymphadenopathy on ultrasound. Concurrent pneumonia is common. The prognosis is less favorable than for pulmonary disease alone. ## Causes Rhodococcus equi. ## Diagnosis Ultrasound of the abdomen and thorax, and culture or polymerase chain reaction. ## Treatment Prolonged combination antibiotic therapy (often a macrolide plus rifampin). Supportive care. Response is variable. ## Recovery and Prognosis Guarded. Abdominal involvement worsens the outlook compared with lung-only disease. ## Prevention Farm-specific management and early screening on endemic farms. Signs include: chronic diarrhea in foals; weight loss; pot-bellied appearance; abdominal lymphadenopathy on ultrasound; often concurrent pneumonia
Chronic granulomatous inflammation of the intestinal wall and mesenteric lymph nodes. May be associated with Mycobacterium avium subsp. paratuberculosis (though true Johne's disease is very rare in horses) or idiopathic granulomatous enteritis. Signs include: Chronic weight loss; diarrhea; hypoproteinemia; thickened intestinal wall and enlarged mesenteric lymph nodes; poor response to treatment
These nodes are not directly accessible but can be assessed by rectal palpation of the mesenteric root, transabdominal ultrasound, and abdominocentesis. Markedly enlarged nodes palpable per rectum can suggest lymphosarcoma or metastatic (bastard) strangles. Normal mesenteric nodes are not individually palpable. Peritoneal fluid analysis may show neoplastic lymphocytes or inflammatory cells depending on the disease.
Unexplained weight loss, fever, or abdominal discomfort with other systemic signs should be evaluated. The veterinarian may assess the mesenteric root during a rectal examination.
See the Mesenteric Lymph Nodes on our interactive 3D horse model. Open 3D Model