Guttural Pouch Infections in Horses: Signs, Treatment and When It Is an Emergency

By Dr Duncan Houston

Guttural pouch disease is one of those equine problems that can look minor until it suddenly becomes very serious. A horse may only have a one-sided nasal discharge, a mild cough, or intermittent bloody discharge, but the guttural pouches sit beside major arteries and important cranial nerves. That anatomy is exactly why some guttural pouch infections can become life-threatening.

The two big categories owners need to understand are bacterial guttural pouch empyema and guttural pouch mycosis. Empyema usually means pus in the guttural pouch, often linked to strangles or other upper respiratory infection. Mycosis is a fungal infection, and it is the scary one because it can erode into major arteries and cause sudden, severe bleeding.

This article explains what the guttural pouches are, which signs matter most, when bloody nasal discharge is an emergency, how vets diagnose guttural pouch infections, and how treatment differs between bacterial and fungal disease.

Quick Answer

Guttural pouch infections in horses can be bacterial or fungal. Bacterial guttural pouch empyema usually causes pus, nasal discharge, fever, throatlatch swelling, or chronic strangles carrier problems, and often needs endoscopy, culture or PCR testing, repeated flushing, and sometimes removal of firm pus balls called chondroids. Guttural pouch mycosis is more dangerous because fungal plaques can grow over major arteries and cause sudden, potentially fatal nosebleeds, so any unexplained bloody nasal discharge should be treated as an emergency. (Merck Veterinary Manual)

What Is the Guttural Pouch?

The guttural pouches are air-filled extensions of the Eustachian tubes found in horses and a few related species. There is one guttural pouch on each side, located near the throatlatch below the ear. Their exact function is still not fully understood, although proposed roles include pressure equalisation, vocal resonance, warming air, and possibly cooling blood flowing toward the brain during exercise. (American College of Veterinary Surgeons)

The clinically important part is what runs along the guttural pouch walls. Major arteries, including the internal carotid, external carotid and maxillary arteries, pass close to or within the walls of the pouch. Important cranial nerves involved in swallowing, upper airway function and facial movement also run through this region. (American College of Veterinary Surgeons)

That is why guttural pouch disease is not just a “nasal discharge problem.” It can become a bleeding problem, a swallowing problem, an airway problem, or an infectious disease control problem.

The Two Main Guttural Pouch Infections

The two main infectious conditions owners should know are:

These are very different problems. Bacterial empyema is often treatable with repeated flushing and targeted therapy. Mycosis is often treated as a surgical emergency because the next nosebleed can be fatal.

Guttural Pouch Empyema

Guttural pouch empyema means pus has accumulated inside one or both guttural pouches. It commonly develops after an upper respiratory bacterial infection, especially Streptococcus species, including strangles. A retropharyngeal lymph node abscess can rupture and drain into the guttural pouch, leaving infected material trapped inside. (Merck Veterinary Manual)

Signs may include:

• Thick white, yellow, or green nasal discharge

• One-sided nasal discharge

• Fever

• Depression

• Reduced appetite

• Painful swelling near the throatlatch or parotid area

• Enlarged lymph nodes

• Stiff head carriage

• Noisy breathing

• Difficulty swallowing in severe cases

The discharge can come and go because it may drain intermittently from the guttural pouch into the throat and nose. That is why some horses seem to improve, then start discharging again.

Chondroids: Why Some Horses Become Chronic Carriers

If pus sits in the guttural pouch for long enough, it can dry out and form firm balls called chondroids. These chondroids can trap bacteria and allow a horse to look outwardly healthy while still shedding infectious organisms, especially after strangles. (AAEP)

This is one of the reasons strangles control can be so frustrating. The horse may no longer look sick, but the guttural pouch can still harbour infectious material.

For strangles clearance, guttural pouch endoscopy and lavage PCR are important tools. Cornell’s diagnostic guidance notes that endoscopic examination and washes of both guttural pouches should be performed in horses with positive PCR or culture, and that repeated negative guttural pouch washes may be needed to confirm negative status. (Cornell Vet College)

In plain English: a horse can look recovered and still be part of the outbreak problem. Sneaky little biological chaos machine.

Guttural Pouch Mycosis

Guttural pouch mycosis is a fungal infection of the guttural pouch. It is uncommon, but it is one of the most dangerous guttural pouch diseases because fungal plaques often develop over major arteries. Aspergillus is the most commonly identified fungus. (Merck Veterinary Manual)

The major danger is that the fungal plaque can erode through the wall of an artery. When that happens, the horse can have sudden severe epistaxis, which means bleeding from the nose. Smaller nosebleeds may occur before a fatal bleed, but sometimes the first obvious bleed is already catastrophic. (American College of Veterinary Surgeons)

Signs of guttural pouch mycosis may include:

• Bright red blood from one or both nostrils

• Recurrent mild nosebleeds

• Sudden severe nasal bleeding

• Difficulty swallowing

• Dropping feed

• Coughing while eating

• Feed or fluid coming from the nose

• Noisy breathing

• Facial asymmetry

• Horner’s syndrome signs, such as drooping eyelid or constricted pupil

• Abnormal head posture

• Pain near the throatlatch

The most important owner rule is simple: any unexplained nosebleed in a horse should be taken seriously, and recurrent or moderate to severe bleeding is an emergency.

Why Guttural Pouch Mycosis Is So Dangerous

The fungal plaque does not need to be huge to be dangerous. ACVS notes that fungal plaques can vary in size, and plaque size does not necessarily match disease severity. The issue is where the plaque sits and whether it has damaged a blood vessel or nerve. (American College of Veterinary Surgeons)

Merck Veterinary Manual describes guttural pouch mycosis as life-threatening and reports fatal haemorrhage in almost half of cases. The most common sign is spontaneous severe epistaxis caused by fungal erosion into the internal carotid artery or branches of the external carotid artery, and repeated bleeds can occur before a fatal episode. (Merck Veterinary Manual)

The other major concern is nerve damage. If the fungus affects cranial nerves, the horse may have dysphagia, which means difficulty swallowing. Dysphagia is a poor prognostic sign and may require intensive supportive care even after the bleeding risk is controlled. (Merck Veterinary Manual)

How Worried Should You Be?

Low Risk

This is lower concern if the horse has mild clear nasal discharge, no fever, normal appetite, normal breathing, no throatlatch swelling, and no blood.

What to do: monitor closely, reduce dust exposure, and arrange a vet check if the discharge persists, becomes thick, becomes one-sided, or the horse develops fever or cough.

Moderate Risk

This is more concerning if the horse has thick nasal discharge, mild fever, throatlatch swelling, cough, recent strangles exposure, or discharge that keeps returning.

What to do: call your vet. Guttural pouch empyema, strangles, sinus disease, dental disease and lower airway infection may need to be ruled out.

High Risk

This is high concern if the horse has one-sided thick discharge, suspected strangles, difficulty swallowing, noisy breathing, facial nerve signs, recurrent nasal discharge after apparent recovery, or known chondroids.

What to do: the horse needs veterinary assessment, likely endoscopy, and testing such as culture or PCR where infection control matters.

Critical

This is an emergency if there is any moderate to severe nosebleed, repeated nosebleeds, sudden bright red blood from the nose, difficulty breathing, severe swallowing difficulty, collapse, weakness, pale gums, or distress.

What to do: call a vet urgently. Do not exercise, transport, or delay while waiting to see if the bleeding returns.

When Is This an Emergency?

Call a vet immediately if your horse has:

• Sudden bleeding from one or both nostrils

• Recurrent nosebleeds, even if each one is small

• Bright red blood from the nose

• Heavy or continuous nasal bleeding

• Pale gums, weakness, sweating, collapse, or shock

• Difficulty swallowing

• Feed or water coming from the nose

• Severe noisy breathing

• Struggling to breathe

• Facial paralysis or sudden facial asymmetry

• Fever with throatlatch swelling

• Suspected strangles with worsening breathing

• Thick discharge plus depression or reduced appetite

ACVS states that any episode of blood from one or both nostrils should be considered an emergency because smaller bleeds can precede a fatal haemorrhage in guttural pouch mycosis. (American College of Veterinary Surgeons)

If your horse is actively bleeding, keep them calm, avoid excitement, and wait for veterinary direction. Do not force exercise. Do not put the horse on a trailer unless your vet specifically advises it, because stress and movement can worsen bleeding.

What Else Can Look Like Guttural Pouch Disease?

Not every nasal discharge or nosebleed comes from the guttural pouch.

Important rule-outs include:

• Strangles

• Viral respiratory infection

• Bacterial pneumonia

• Sinus infection

• Tooth root infection

• Ethmoid haematoma

• Trauma to the nose or head

• Exercise-induced pulmonary haemorrhage

• Foreign body in the nasal passage

• Nasal or sinus mass

• Guttural pouch tympany

• Temporohyoid osteoarthropathy

• Hyoid apparatus disease

• Facial nerve injury

• Choke

• Upper airway obstruction

• Coagulation disorder

The pattern matters. One-sided thick discharge may point toward sinus, dental or guttural pouch disease. Bright red spontaneous nosebleeding raises guttural pouch mycosis much higher on the concern list. Difficulty swallowing or feed coming from the nose suggests cranial nerve or pharyngeal dysfunction, and guttural pouch disease is one important rule-out.

How Vets Diagnose Guttural Pouch Infections

Endoscopy

Endoscopy is the main diagnostic tool. A flexible camera is passed through the nasal passage and into the guttural pouch openings, allowing the vet to directly inspect the pouches. It can show pus, chondroids, fungal plaques, blood clots, retropharyngeal abscess drainage, and whether one or both pouches are affected. Merck and AAEP both describe endoscopic examination of the guttural pouches as central to diagnosis. (Merck Veterinary Manual)

For guttural pouch mycosis, ACVS describes endoscopy as the gold standard because it allows direct visualisation of the fungal plaques, which often appear as white, tan, black or membrane-like material over blood vessels. (American College of Veterinary Surgeons)

Culture and PCR

If bacterial infection or strangles is suspected, samples from guttural pouch fluid can be submitted for culture and PCR. Merck notes that culture or PCR of purulent material can identify Streptococcus equi or other bacterial infection, while AAEP highlights culture and PCR testing from guttural pouch fluid when ruling out strangles shedding. (Merck Veterinary Manual)

PCR can detect bacterial DNA, so timing and interpretation matter. Cornell notes that PCR may detect DNA from live, dead, or vaccine-origin bacteria, which means results need clinical context. (Cornell Vet College)

Radiographs

Radiographs can show fluid lines or chondroid material in the guttural pouch and may identify an associated retropharyngeal mass, but endoscopy is usually more definitive. (Merck Veterinary Manual)

CT or Advanced Imaging

CT may be useful in complicated cases, especially where surgery is being planned, where there is concern about hyoid disease, masses, deep abscesses, or complex anatomy. It is not needed for every case, but it can help when endoscopy and radiographs do not answer the full question.

Treatment for Guttural Pouch Empyema

Treatment depends on the amount of pus, whether chondroids are present, whether strangles is involved, and whether the horse is systemically unwell.

Treatment may include:

• Repeated guttural pouch lavage

• Culture or PCR-guided antibiotic decisions

• Direct medication into the guttural pouch in selected cases

• Supportive care for fever, pain or dehydration

• NSAIDs when appropriate

• Isolation and biosecurity if strangles is suspected

• Endoscopic removal of small chondroids

• Surgical drainage for large chondroid burdens or unresolved abscesses

Merck states that systemic antimicrobial therapy alone rarely resolves guttural pouch empyema and that repeated lavage is necessary. Chondroid material can act as a chronic infection source, and larger accumulations may require surgical drainage. (Merck Veterinary Manual)

AAEP notes that prognosis for empyema is generally good with medical treatment, often involving daily lavage and antibiotic therapy, although surgery may be needed for large chondroids. (AAEP)

The owner takeaway is simple: antibiotics alone are often not enough if pus or chondroids are physically trapped in the pouch. The material needs to come out.

Treatment for Guttural Pouch Mycosis

Guttural pouch mycosis is managed very differently from bacterial empyema.

The main treatment goal is to prevent fatal bleeding by blocking blood flow through the affected artery segment. This may be done with:

• Balloon catheter occlusion

• Transarterial coil embolisation

• Vascular plug embolisation

• Surgical ligation in selected situations

• Supportive care, including fluids or blood transfusion if severe blood loss has occurred

ACVS describes balloon catheter occlusion and transarterial coil or plug embolisation as surgical options used to stop blood flow through affected arteries. Once the blood supply to the fungal plaque is removed, the fungal lesion often regresses. (American College of Veterinary Surgeons)

Medical antifungal treatment alone can be slow and unreliable. ACVS notes that topical antifungal therapy may take months and still leaves the horse at risk of fatal bleeding while the fungal plaque remains active, so medical treatment alone is not usually recommended for many cases. (American College of Veterinary Surgeons)

K-State’s equine surgery guidance also describes emergency care such as intravenous fluids and blood transfusion when severe haemorrhage occurs, with arterial occlusion needed to stop the bleeding risk. (Veterinary Health Center)

This is why a nosebleed from guttural pouch mycosis is not a “try some medication and monitor” situation. It is often a referral-level surgical problem.

Aftercare and Prognosis

Empyema

Many horses with guttural pouch empyema recover well if the infected material is cleared, the underlying infection is managed, and carrier status is addressed. The prognosis is better when there is no airway obstruction, no large chondroid burden, no severe nerve involvement, and biosecurity is handled properly. (AAEP)

Mycosis

For guttural pouch mycosis, prognosis depends heavily on whether the horse survives the bleeding episode and whether nerve damage is already present. ACVS notes that horses treated quickly after a significant nosebleed often have a good prognosis if bleeding is the only sign, but recovery is more complicated when dysphagia or upper airway dysfunction is present. Nerve recovery can take months and may be incomplete. (American College of Veterinary Surgeons)

The brutal truth is this: the first bleed might not be the last, and the next bleed might be fatal. Early diagnosis and referral can be life-saving.

What Should You Do Right Now?

If your horse has thick nasal discharge, suspected guttural pouch infection, or a recent respiratory infection:

1. Do not assume it is just a cold.

2. Take the horse’s temperature.

3. Note whether discharge is one-sided or both-sided.

4. Look for throatlatch swelling.

5. Watch for difficulty swallowing, coughing while eating, or feed from the nose.

6. Keep the horse separated if strangles is possible.

7. Do not transport a horse with suspected contagious respiratory infection unless your vet advises it.

8. Call your vet for examination and possible endoscopy.

9. Ask whether culture or PCR testing is needed.

10. Follow biosecurity instructions until infectious disease is ruled out.

If your horse has bloody nasal discharge:

1. Treat it as urgent.

2. Keep the horse calm and still.

3. Do not exercise the horse.

4. Do not scope or flush anything yourself, obviously.

5. Call your vet immediately.

6. Be ready for referral if guttural pouch mycosis is suspected.

AAEP specifically advises that horses with suspected respiratory infection should not be transported until examined by a veterinarian, and notes that some Streptococcus equi infections may be reportable depending on location. (AAEP)

Common Mistakes Owners Make

Ignoring Mild Recurrent Nosebleeds

A small bleed can precede a fatal bleed in guttural pouch mycosis. Recurrent epistaxis should never be brushed off.

Treating Empyema With Antibiotics Alone

If pus or chondroids are trapped in the pouch, systemic antibiotics alone may not resolve the problem. Repeated lavage or removal of chondroids may be needed. (Merck Veterinary Manual)

Missing Strangles Carrier Status

A horse can look healthy but continue shedding Streptococcus equi from guttural pouch chondroids. This can restart outbreaks and annoy absolutely everyone on the property.

Transporting a Suspected Infectious Horse

Moving a horse with suspected strangles or contagious respiratory disease can spread infection to other facilities. Call your vet first. (AAEP)

Waiting Too Long With Dysphagia

Difficulty swallowing can indicate cranial nerve involvement. It also increases the risk of aspiration pneumonia, dehydration and poor outcome.

Assuming Nasal Discharge Is Always Sinus Disease

Sinus and dental problems are common, but guttural pouch disease is an important rule-out, especially with one-sided discharge, strangles history, dysphagia, or blood.

Can Guttural Pouch Infections Be Prevented?

Not every guttural pouch problem can be prevented, especially guttural pouch mycosis, where the exact cause is still not fully understood. But some risks can be reduced.

Practical prevention and control steps include:

• Isolate horses with suspected strangles or contagious respiratory disease.

• Use appropriate culture or PCR testing in outbreak situations.

• Follow veterinary clearance protocols after strangles.

• Investigate chronic nasal discharge early.

• Do not ignore throatlatch swelling or recurrent fever.

• Maintain good biosecurity for new arrivals.

• Avoid sharing contaminated equipment between horses.

• Clean and disinfect high-contact surfaces during respiratory outbreaks.

• Keep recovered strangles horses under veterinary guidance until carrier risk is addressed.

• Investigate any unexplained nosebleed promptly.

For bacterial empyema, prevention is largely about good infectious disease control. For mycosis, prevention is much harder, so early recognition is the real life-saver.

Will My Horse Be Okay?

Many horses with guttural pouch empyema recover well with proper flushing, testing, and treatment. The prognosis is usually good when the horse is diagnosed early and large chondroids or airway obstruction are not present. (AAEP)

Guttural pouch mycosis is more serious. The prognosis is better when the horse is treated before catastrophic blood loss and before major nerve dysfunction develops. If the horse already has severe dysphagia, facial nerve signs, upper airway dysfunction, or repeated haemorrhage, the prognosis is more guarded. (Merck Veterinary Manual)

The key decision point is simple: pus from the nose needs a vet check, and blood from the nose needs urgent attention.

FAQs

What are the signs of a guttural pouch infection in horses?

Signs can include thick nasal discharge, fever, depression, throatlatch swelling, painful swallowing, noisy breathing, difficulty eating, facial nerve changes, and in fungal cases, bloody nasal discharge. Empyema often causes pus, while mycosis often presents with nosebleeds or nerve signs. (Merck Veterinary Manual)

Is a nosebleed in a horse always an emergency?

Not every nosebleed has the same cause, but unexplained, recurrent, moderate or severe bleeding should be treated as urgent. Guttural pouch mycosis can cause smaller bleeds before a fatal haemorrhage, so it should be ruled out quickly. (American College of Veterinary Surgeons)

How do vets diagnose guttural pouch disease?

Endoscopy is the key test because it allows direct inspection of the guttural pouches. Vets may also use radiographs, culture, PCR testing, cytology, or advanced imaging depending on whether empyema, strangles, mycosis, chondroids, or another condition is suspected. (Merck Veterinary Manual)

Can guttural pouch empyema make a horse a strangles carrier?

Yes. Chronic pus or chondroids in the guttural pouch can harbour Streptococcus equi and allow an apparently healthy horse to shed bacteria. Endoscopy and guttural pouch lavage PCR or culture are important in identifying carrier horses. (AAEP)

Can guttural pouch mycosis be treated with antifungals alone?

Medical treatment with topical or systemic antifungals can be slow and variable, and the horse remains at risk of sudden fatal bleeding while the plaque is active. Many cases require surgical or interventional occlusion of the affected artery to reduce haemorrhage risk. (American College of Veterinary Surgeons)

Final Thoughts

Guttural pouch infections are uncommon compared with routine respiratory disease, but they matter because the guttural pouches sit beside structures horses cannot afford to damage: major arteries, swallowing nerves, airway nerves and facial nerves.

Bacterial empyema is usually a problem of trapped pus, strangles complications, chronic discharge and carrier risk. It often needs endoscopy, flushing, testing and sometimes chondroid removal. Mycosis is different. It is a fungal disease that can erode into an artery and cause sudden fatal bleeding.

The main takeaway is simple: thick discharge should be investigated, chronic post-strangles horses may need guttural pouch testing, and bloody nasal discharge is never something to casually watch from the gate.

Early endoscopy can turn a mystery discharge into a treatment plan. In the case of guttural pouch mycosis, it can save the horse’s life.

If your horse has chronic nasal discharge, suspected strangles carrier status, difficulty swallowing, noisy breathing, or any unexplained nosebleed, ASK A VET™ can help you understand what signs to monitor and what questions to ask your treating vet before the next diagnostic or treatment step.