Sinusitis in Sheep: Nasal Discharge, Facial Swelling and Treatment

Quick Answer
  • Sinusitis in sheep is inflammation or infection of the sinuses, often linked to nasal bot larvae, secondary bacterial infection, trauma, foreign material, or less commonly tumors.
  • Common signs include one-sided or two-sided nasal discharge, sneezing, reduced airflow from a nostril, noisy breathing, and facial swelling over the sinuses.
  • See your vet promptly if discharge is thick, foul-smelling, bloody, lasts more than a few days, or if your sheep is off feed, feverish, or struggling to breathe.
  • Treatment depends on the cause and may include antiparasitic medication, antibiotics chosen by your vet, anti-inflammatory care, drainage, or surgery in severe cases.
Estimated cost: $75–$1,200

What Is Sinusitis in Sheep?

Sinusitis in sheep means inflammation of the sinuses, the air-filled spaces connected to the nasal passages inside the skull. When these spaces become irritated, blocked, or infected, mucus and inflammatory material can build up. That can lead to nasal discharge, sneezing, reduced airflow through one or both nostrils, and sometimes visible swelling of the face.

In sheep, sinus problems are not always a straightforward "sinus infection." They can develop after irritation from nasal bot larvae (Oestrus ovis), from secondary bacterial infection, after trauma, or alongside other upper airway problems. In some cases, dead or trapped larvae in the sinuses can contribute to septic sinusitis.

Because several conditions can look similar at first, including foreign bodies, nasal tumors, tooth-root disease, and severe upper respiratory irritation, a farm call or clinic exam matters. Your vet can help sort out whether this is a mild upper airway issue, a true sinus problem, or a more serious condition affecting breathing or the bones of the face.

Symptoms of Sinusitis in Sheep

  • Nasal discharge from one nostril
  • Nasal discharge from both nostrils
  • Clear, mucoid, or thick mucopurulent discharge
  • Sneezing or repeated snorting
  • Reduced airflow through one nostril
  • Noisy breathing or mild respiratory distress
  • Facial swelling or facial asymmetry
  • Blood-tinged discharge
  • Off feed, weight loss, or poor condition
  • Open-mouth breathing or marked breathing effort

Mild cases may start with sneezing and a clear or cloudy nasal discharge. As inflammation worsens, discharge can become thicker, more persistent, and sometimes foul-smelling or blood-tinged. Sheep with more advanced disease may have reduced airflow from one nostril, cough from drainage, or show swelling over the face or sinus area.

See your vet immediately if your sheep has open-mouth breathing, severe breathing noise, rapid decline, obvious facial deformity, fever, or stops eating. A one-sided discharge that keeps coming back also deserves a closer workup, because chronic unilateral signs can point to a trapped foreign body, dental disease, a sinus abscess, or a mass rather than a routine irritation.

What Causes Sinusitis in Sheep?

Sinusitis in sheep usually develops when normal drainage from the nasal passages and sinuses is disrupted. One important sheep-specific cause is nasal bot infestation. Oestrus ovis larvae live in the nasal passages and sinuses, causing irritation, sneezing, and discharge. If larvae die and cannot escape, they may calcify or contribute to septic sinusitis.

Secondary bacterial infection can follow irritation, trauma, or blockage. Dust, poor ventilation, smoke exposure, and crowded housing can also irritate the upper airway and make infection more likely. In individual sheep, foreign material in the nose, facial trauma, or extension of infection from nearby tissues may also be involved.

Less common but important look-alikes include enzootic nasal tumors, polyps, and other masses that can cause chronic discharge, reduced airflow, exophthalmos, or facial deformity as they enlarge. That is why persistent or one-sided signs should not be assumed to be a routine sinus problem. Your vet may need to rule out several causes before deciding on the most appropriate care plan.

How Is Sinusitis in Sheep Diagnosed?

Your vet will start with a full history and physical exam, including how long the discharge has been present, whether it is one-sided or two-sided, whether the sheep is eating normally, and whether there is any facial swelling or breathing difficulty. The character of the discharge matters too. Clear discharge suggests a different set of causes than thick pus, blood, or a foul odor.

In many field cases, your vet can make a working diagnosis from the exam and flock history. If the problem is chronic, severe, or not responding to treatment, additional testing may be recommended. This can include skull radiographs to look for fluid, bone changes, dental involvement, or masses. In referral settings, endoscopy, advanced imaging, or sampling for culture may be used.

Diagnosis is also about ruling out other causes of nasal discharge. Your vet may consider nasal bots, foreign bodies, tooth-root disease, trauma, abscesses, and tumors. If there is facial deformity, poor airflow, or repeated relapse, a more detailed workup becomes especially important before choosing treatment.

Treatment Options for Sinusitis in Sheep

Spectrum of Care means you have options. Here are treatment tiers at different price points.

Budget-Conscious Care

$75–$180
Best for: Mild early cases, flock situations where nasal bot exposure is likely, or sheep that are stable and still eating well.
  • Farm-call or basic exam
  • Temperature check and airway assessment
  • Targeted antiparasitic treatment if nasal bots are strongly suspected, such as ivermectin when appropriate for the animal and production status
  • Supportive care recommendations, including cleaner air, lower dust exposure, and close monitoring of appetite and breathing
Expected outcome: Often fair to good when signs are mild and the underlying cause is uncomplicated irritation or nasal bot infestation.
Consider: This approach may not identify deeper infection, abscessation, dental disease, or a mass. If signs persist, recur, or worsen, more diagnostics are usually needed.
Most Common

Recommended Standard Treatment

$180–$450
Best for: Most sheep with persistent discharge, facial swelling, reduced airflow, or suspected secondary bacterial infection.
  • Complete veterinary exam
  • Anti-inflammatory treatment and prescription medications selected by your vet
  • Antibiotic therapy when bacterial sinusitis is suspected or confirmed
  • Follow-up exam to assess airflow, discharge, and response to treatment
  • Basic imaging or sample collection in selected cases
Expected outcome: Good in many uncomplicated cases when the cause is identified early and treatment is matched to the likely source of inflammation or infection.
Consider: Higher cost range than conservative care, and some sheep still need imaging, drainage, or referral if there is chronic blockage, bone involvement, or a mass.

Advanced / Critical Care

$600–$1,200
Best for: Severe, chronic, relapsing, or one-sided cases; sheep with facial deformity; poor response to initial treatment; or concern for abscess, foreign body, dental disease, or tumor.
  • Skull radiographs or referral imaging
  • Endoscopic evaluation or sampling where available
  • Culture and sensitivity testing in complicated infections
  • Surgical drainage, sinus trephination, or debridement when indicated by your vet
  • Hospitalization and intensive monitoring for severe respiratory distress or advanced facial swelling
Expected outcome: Variable. Many infectious or obstructive cases improve with definitive treatment, but prognosis is more guarded if there is extensive bone damage, a tumor, or prolonged breathing compromise.
Consider: This tier offers the most information and intervention, but it requires more handling, referral access in some areas, and a higher cost range.

Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.

Questions to Ask Your Vet About Sinusitis in Sheep

Bring these questions to your vet appointment to get the most out of your visit.

  1. You can ask your vet whether this looks more like sinusitis, nasal bot infestation, a foreign body, or another upper airway problem.
  2. You can ask your vet if the discharge pattern matters, especially if it is one-sided, bloody, foul-smelling, or keeps returning.
  3. You can ask your vet whether antiparasitic treatment is appropriate for this sheep and whether meat or milk withdrawal times apply.
  4. You can ask your vet if antibiotics are likely to help in this case or if more diagnostics should come first.
  5. You can ask your vet whether skull radiographs, endoscopy, or culture would change the treatment plan.
  6. You can ask your vet what signs mean the sheep needs urgent recheck, such as worsening swelling, open-mouth breathing, or going off feed.
  7. You can ask your vet whether other sheep in the flock are at risk and if group-level parasite control or management changes are recommended.

How to Prevent Sinusitis in Sheep

Prevention starts with reducing irritation and improving airflow. Keep housing as dry, clean, and well ventilated as possible. Limit dust from bedding, hay, and feed when you can, and pay attention to smoke or poor air quality events because respiratory irritation can make upper airway disease worse.

Good parasite control also matters. In regions where sheep nasal bots are common, your vet may recommend a flock plan that includes strategic antiparasitic treatment and seasonal monitoring. Because treatment timing can vary by climate, management system, and local parasite pressure, it is best to build that plan with your vet rather than guessing.

Watch for chronic one-sided nasal discharge, repeated sneezing, or facial asymmetry and act early. Prompt evaluation can prevent a mild problem from becoming a deeper infection or a chronic sinus issue. Quarantine and observe newly introduced animals when practical, and keep records on recurring respiratory signs so your vet can spot flock-level patterns.

Find a Vet Near You