Lymphonodi mandibulares
The submandibular (mandibular) lymph nodes are a group of 2-5 nodes located in the intermandibular space, between the rami of the mandible, embedded in loose connective tissue and the mandibular salivary gland. They are the sentinel lymph nodes for the oral cavity, rostral nasal passages, lower lip, and chin. Afferent lymph drains from the teeth, gums, tongue, floor of the mouth, and nasal vestibule. Efferent lymph drains to the retropharyngeal lymph nodes. These nodes are the most clinically important palpable lymph nodes in routine equine examination.
Enlargement is common with dental disease, oral infections, strangles, and other upper respiratory or oral conditions. They are routinely palpated during physical examination. Persistent enlargement, pain, or asymmetry warrants further investigation.
Strangles is a highly contagious upper respiratory infection caused by the bacterium *Streptococcus equi* subsp. *equi*. It is one of the most commonly diagnosed infectious diseases of horses worldwid
Non-strangles bacterial abscessation, commonly from Streptococcus equi subsp. zooepidemicus, Corynebacterium pseudotuberculosis (pigeon fever), or other opportunistic organisms entering through mucosa
## Overview Multicentric lymphosarcoma is the most common form of lymphoma in adult horses. Malignant lymphocytes involve multiple lymph-node groups and often internal organs. Signs include generaliz
Swollen nodes under the jaw, especially with fever or nasal discharge, should be evaluated. They are easy to palpate and are part of a normal physical exam.
Strangles is a highly contagious upper respiratory infection caused by the bacterium *Streptococcus equi* subsp. *equi*. It is one of the most commonly diagnosed infectious diseases of horses worldwide and is characterized by fever, nasal discharge, and abscessation of the submandibular and retropharyngeal lymph nodes. "Bastard strangles" refers to metastatic spread of abscesses to other parts of the body. ## What it is *Streptococcus equi* infects the upper respiratory tract and local lymph nodes, causing marked inflammation and abscess formation. The bacteria are highly contagious and spread through direct contact, shared equipment, or aerosolized droplets. After infection, some horses become carriers and can shed the organism intermittently for months or years without showing signs. The disease is most common in young horses but can affect horses of any age. Outbreaks can occur in any setting where horses are in close contact. ## Signs and symptoms - Fever (often 39.5 to 41 degrees C / 103 to 106 degrees F) - Mucopurulent nasal discharge - Painful, swollen submandibular and retropharyngeal lymph nodes that eventually abscess and rupture - Dysphagia (difficulty swallowing) and extended head and neck posture - Depression, anorexia, and lethargy - In bastard strangles: abscesses in unusual locations (lungs, abdomen, brain, or other organs) causing more serious systemic illness ## Causes and risk factors Strangles is caused by *Streptococcus equi* subsp. *equi*. Risk factors include young age, stress, overcrowding, poor ventilation, and introduction of new horses to a group. Horses that have recovered from strangles can become asymptomatic carriers and serve as a source of infection for others. ## How it is diagnosed Diagnosis is based on clinical signs and confirmed by culture or PCR testing of nasal swabs, pus from abscesses, or guttural pouch lavage. Serology (blood tests) can help identify exposure or carrier status. In outbreaks, identifying carrier horses is important for controlling spread. ## Treatment and management Treatment depends on the stage and severity. Many cases are managed supportively with rest, soft feed, and pain relief while the lymph nodes abscess and drain. Antibiotics are sometimes used in early cases or in severe systemic illness but can prolong the carrier state if used inappropriately. In bastard strangles, aggressive antibiotic and supportive therapy is required. Strict biosecurity measures, including isolation of affected horses and disinfection of equipment, are essential to control outbreaks. ## When to call the vet Contact your veterinarian immediately if your horse develops fever, nasal discharge, or swollen lymph nodes. Strangles is highly contagious, and early diagnosis and isolation help limit spread within a barn or facility. ## Prevention Prevention relies on good biosecurity practices: quarantining new horses, avoiding shared equipment and water sources during outbreaks, and maintaining good stable hygiene. Vaccines are available but provide incomplete protection. Regular screening for carriers in endemic areas can help reduce outbreaks. ## Frequently asked questions **How long is a horse contagious with strangles?** Horses can shed the bacteria for weeks to months after clinical signs resolve. Some become long-term carriers. **Can strangles be fatal?** Most cases are not fatal, but bastard strangles (metastatic abscesses) and complications such as airway obstruction or pneumonia can be life-threatening. **Should antibiotics always be used for strangles?** Not always. Many uncomplicated cases resolve with supportive care. Antibiotics are often reserved for severe cases or to treat complications. This information is for educational purposes only. Always consult with a licensed veterinarian for diagnosis and treatment of your horse. Signs include: Fever (often 39.5 to 41 degrees C / 103 to 106 degrees F); mucopurulent nasal discharge; painful, swollen submandibular and retropharyngeal lymph nodes that eventually abscess and rupture; dysphagia (difficulty swallowing) and extended head and neck posture; depression, anorexia, and lethargy; in bastard strangles: abscesses in unusual locations causing more serious systemic illness
Non-strangles bacterial abscessation, commonly from Streptococcus equi subsp. zooepidemicus, Corynebacterium pseudotuberculosis (pigeon fever), or other opportunistic organisms entering through mucosal abrasions. Signs include: Firm to fluctuant swelling in intermandibular space; pain on palpation; fever; nasal discharge; may rupture and drain
## Overview Multicentric lymphosarcoma is the most common form of lymphoma in adult horses. Malignant lymphocytes involve multiple lymph-node groups and often internal organs. Signs include generalized lymph-node enlargement, weight loss, ventral edema, intermittent fever, anemia, and elevated globulins. ## Causes Neoplastic proliferation of lymphocytes. No specific cause is identified. ## Diagnosis Enlarged nodes on examination, cytology or biopsy showing a monomorphic lymphoid population, and staging with ultrasound or radiographs. ## Treatment Corticosteroids may produce temporary improvement. Chemotherapy protocols exist but responses are usually short-lived. Most care is palliative. ## Recovery and Prognosis Poor. Survival is typically weeks to a few months after diagnosis. ## Prevention None. Signs include: generalized peripheral lymphadenopathy; weight loss; ventral edema; intermittent fever; anemia; hyperglobulinemia
Enlargement is common with dental disease, oral infections, strangles, and other upper respiratory or oral conditions. They are routinely palpated during physical examination. Persistent enlargement, pain, or asymmetry warrants further investigation.
Swollen nodes under the jaw, especially with fever or nasal discharge, should be evaluated. They are easy to palpate and are part of a normal physical exam.
See the Submandibular Lymph Nodes on our interactive 3D horse model. Open 3D Model