Horse Care: Understanding Strangles in Horses

Understanding Strangles in Horses: A Complete Care Guide

Strangles is a highly contagious bacterial infection that affects horses of all ages, though it is most commonly seen in younger animals. The disease is caused by the gram-positive bacterium Streptococcus equi equi, which primarily affects the upper respiratory tract and lymph nodes of infected horses. This condition is comparable to strep throat in humans, but the manifestations in horses are often more dramatic, with infected animals developing large abscessed lymph nodes and high fevers. Understanding strangles is essential for any horse owner, as early recognition and proper management can significantly impact the outcome and prevent spread to other animals on the property.

What Causes Strangles?

Strangles is transmitted from horse to horse through respiratory secretions, making it one of the most contagious diseases affecting equines. The bacterium Streptococcus equi equi enters the body through the respiratory tract and establishes infection in the lymph nodes of the head and neck region. The disease gets its name from the characteristic swelling and abscessation of the submandibular lymph nodes, which can restrict the airway and make swallowing difficult. While the infection typically remains localized to the upper respiratory tract, complications can occasionally arise that affect other body systems.

Recognizing the Symptoms of Strangles

Horse owners should be vigilant about observing their animals for early signs of strangles. The initial symptom is typically a fever, which appears within 24 to 48 hours of infection. Within this same timeframe, infected horses will develop characteristic clinical signs that help veterinarians confirm the diagnosis.

Primary Clinical Signs

The most common symptoms of strangles include:

• Mucoid to mucopurulent nasal discharge from one or both nostrils
• Depression and lethargy
• Submandibular lymphadenopathy (swelling of lymph nodes under the jaw)
• Abscessation of the lymph nodes, which may rupture and drain purulent material
• Difficulty swallowing
• Reduced appetite
• Inspiratory respiratory noise or difficulty breathing
• Extended head and neck posture

Complications and Severe Manifestations

In some cases, the infection can spread beyond the initial lymph node involvement. When pus accumulates within the guttural pouches—air-filled spaces within the head that drain through the nasal passages—a condition called empyema develops. This leads to persistent nasal discharge from the affected side. In severe cases, horses may experience inability to chew and swallow properly, which can result in feed and water flowing from the nostrils, a condition known as choke.

How is Strangles Diagnosed?

Accurate diagnosis is crucial for confirming strangles and implementing appropriate management protocols. Veterinarians use several diagnostic methods to confirm the presence of Streptococcus equi equi infection. Diagnosis relies on culture or polymerase chain reaction (PCR) testing of abscess material or washes collected from the guttural pouch or nasopharynx. In complicated cases, an endoscopy of the upper respiratory tract may be required to visualize the extent of infection and identify the location of abscesses. Ultrasound and radiographic imaging can also help identify the location and extent of lymph node involvement.

Treatment Approaches for Strangles

The treatment strategy for strangles depends on the severity of clinical signs and whether complications are present. Understanding the appropriate treatment approach is essential for optimizing recovery while preventing unnecessary complications.

Supportive Care as Primary Treatment

For uncomplicated cases of strangles, supportive care is the mainstay of treatment. Most horses with strangles will resolve with only supportive care that includes anti-inflammatory medications and pain relievers. This conservative approach is recommended because horses treated without antibiotics have a higher likelihood of developing long-term immunity to the disease. Approximately 75% of horses that recover from strangles without antibiotic treatment mount a sufficient immune response to develop immunity that lasts 1 to 2 years.

Supportive treatment should include:

• Provision of a warm, dry, and dust-free environment
• Palatable, easy-to-eat feed such as wet, sloppy food from the floor
• Warm compresses applied to sites of lymphadenopathy to facilitate maturation and drainage of abscesses
• Judicious administration of nonsteroidal anti-inflammatory drugs (NSAIDs) to decrease pain and fever and to improve appetite
• Close monitoring of pain management and adequate consumption of food and water
• Facilitated drainage of mature abscesses to speed recovery

When Antibiotics Are Necessary

Contrary to common assumptions, antibiotics are not routinely recommended for strangles. In fact, antibiotics may actually prolong the duration of disease in uncomplicated cases and are therefore contraindicated in horses with mild to moderate clinical signs. However, antimicrobial treatment becomes necessary in specific situations. Antibiotics are indicated in cases with dyspnea (difficulty breathing), dysphagia (difficulty swallowing), prolonged high fever, severe lethargy or anorexia, and complicated manifestations of the disease such as metastatic strangles, purpura hemorrhagica, or myositis.

When antibiotics are deemed necessary, procaine penicillin is the antimicrobial of choice, typically administered at a dose of 22,000 IU/kg intramuscularly every 12 hours. Antibiotics may also be used during a strangles outbreak on a farm, as early identification of horses with fever and subsequent antibiotic treatment can prevent them from developing clinical strangles.

Managing Persistent Infections

Approximately 10% of horses affected in a strangles outbreak experience a failure of guttural pouch drainage and develop a persistent infection that can lead to recurrent cases of disease. Farms with recurring cases of strangles should be investigated for asymptomatic carriers through endoscopic examination of all horses on the property. Endoscopic examination of the guttural pouches of a carrier horse often reveals concretions of Streptococcus equi pus called chondroids. Once the carrier horse is identified, veterinarians may prescribe a treatment plan that includes chondroid removal and guttural pouch flushing to prevent further outbreaks.

Prevention and Vaccination Strategies

Prevention is always preferable to treatment when dealing with infectious diseases like strangles. Several strategies can help reduce the incidence and spread of this highly contagious disease within equine populations.

Quarantine Protocols

Reducing the exposure of resident or in-contact horses to Streptococcus equi is an effective method of controlling strangles. Quarantining new animals for three weeks and screening for the disease prior to or following arrival is an essential tool for disease prevention. Monitoring body temperature while horses are in quarantine on arrival or following their return from equestrian events provides an early indication of rising temperatures that precede other clinical signs. These quarantine measures are also effective at reducing the risk of incursions of equine influenza virus and equine herpesvirus 1.

Biosecurity Measures During Outbreaks

If an outbreak of strangles occurs on a farm, implementing a comprehensive biosecurity control program is vital:

• Isolation of horses with temperatures of 38.5°C (101.3°F) or above from other horses without clinical signs
• Separation can be as simple as an area of a paddock separated by a double layer of electric fence to eliminate nose-to-nose contact and sharing of drinking water
• Cessation of movement on or off the yard until all cases and other exposed horses have recovered
• Rigorous environmental cleaning and disinfection of shared equipment
• Dedicated care personnel and equipment for affected horses

Vaccination Options

Vaccination is one method for prevention and control of infection with Streptococcus equi, though vaccination cannot guarantee disease prevention. Two main types of vaccines are available. A live attenuated vaccine is administered by submucosal injection into the upper lip, and a multicomponent fusion protein vaccine is administered via intramuscular injection. Both vaccines are indicated to reduce the severity of clinical signs and the formation of abscesses in the lymph nodes following exposure to the bacterium.

With strangles vaccination, the outcome will most likely be a reduction in the severity of disease in the majority of horses infected after vaccination rather than complete prevention. Available vaccines can be administered by intramuscular and intranasal routes, with the intranasal vaccination resulting in the best local immunity. Improper administration of the vaccination can result in poor protection against infection and complications at the injection site; therefore, administration by a veterinarian is recommended.

In studies where foals were deliberately exposed to Streptococcus equi, there was a 74% reduction in the number of foals that developed strangles. Vaccination is only recommended in healthy horses with no fever or nasal discharge. A critical consideration is that vaccination of horses recently exposed to strangles (those with high antibody levels) may result in purpura hemorrhagica, a serious condition caused by an overactive immune response that can result in limb swelling, head swelling, and small hemorrhages on the gums.

Recovery and Long-Term Immunity

Most horses recover completely from strangles with appropriate care and management. Once recovered from an active infection, approximately 75% of horses develop immunity that lasts 1 to 2 years. This natural immunity provides protection against reinfection during this period, though immunity can wane over time. Horses that recover without antibiotic treatment are more likely to develop robust, long-lasting immunity compared to those treated with antibiotics during the acute phase.

Frequently Asked Questions About Strangles

Q: How contagious is strangles?

A: Strangles is highly contagious and spreads rapidly through respiratory secretions. Infected horses should be immediately isolated from other horses to prevent transmission. The disease spreads through nasal discharge, shared water and feed buckets, and nose-to-nose contact.

Q: Can humans catch strangles?

A: No, strangles is a disease that affects horses and is not transmissible to humans. However, humans can carry the bacteria on their hands, clothing, and equipment, potentially transmitting it between horses.

Q: How long does it take for a horse to recover from strangles?

A: Recovery time varies depending on the severity of infection and the individual horse’s immune response. Most horses show improvement within 2 to 3 weeks with proper supportive care, though some cases may take longer.

Q: Should I give my horse antibiotics if diagnosed with strangles?

A: This decision should be made by your veterinarian. Uncomplicated cases typically recover well without antibiotics, and horses treated without antibiotics are more likely to develop long-term immunity. Antibiotics are reserved for complicated cases or those with severe clinical signs.

Q: What is purpura hemorrhagica?

A: Purpura hemorrhagica is a serious immune-mediated condition that can occur when vaccinating horses that have recently been exposed to strangles. It results from an overactive immune response and causes swelling of the limbs and head along with small hemorrhages on the gums.

Q: How can I prevent strangles on my farm?

A: Prevention strategies include quarantining new horses for three weeks, monitoring temperatures during quarantine, implementing strict biosecurity measures, proper vaccination with veterinary guidance, and maintaining good hygiene practices with shared equipment.

Q: Are there permanent effects from strangles?

A: Most horses recover completely from strangles without permanent effects. However, in rare cases where persistent infection develops in the guttural pouches, recurrent disease may occur if not properly treated with guttural pouch drainage and flushing.

Working With Your Veterinarian

Early detection and veterinary consultation are essential when strangles is suspected. Your veterinarian can confirm the diagnosis, determine the appropriate treatment approach based on the severity of clinical signs, monitor recovery progress, and provide guidance on quarantine and biosecurity measures. Regular communication with your veterinarian throughout the infection and recovery period ensures the best possible outcome for your horse and helps prevent transmission to other animals.

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Sneha TeteBeauty & Lifestyle Writer

 

Sneha is a relationships and lifestyle writer with a strong foundation in applied linguistics and certified training in relationship coaching. She brings over five years of writing experience to fluffyaffair,  crafting thoughtful, research-driven content that empowers readers to build healthier relationships, boost emotional well-being, and embrace holistic living.

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