Septic Bursitis in Horses: Infected Bursa, Swelling, and Urgent Care
- See your vet immediately. Septic bursitis is an infection inside or around a bursa, and it can spread to nearby tendon, bone, or other synovial structures.
- Common warning signs include painful swelling, heat, drainage from a wound, lameness, fever, and swelling over the hock, shoulder, poll, or withers.
- Many cases start after trauma or a puncture wound, even when the skin opening looks small.
- Diagnosis often involves a physical exam, ultrasound, radiographs, and sampling bursal fluid or wound discharge for cytology and culture.
- Early lavage, drainage, bandaging, and targeted antibiotics usually give the best chance for recovery and future soundness.
What Is Septic Bursitis in Horses?
Septic bursitis is an infection of a bursa, which is a small fluid-filled sac that helps reduce friction between skin, tendon, ligament, and bone. In horses, bursae near pressure points and high-motion areas can become infected after trauma, a puncture wound, or spread from a nearby infected wound. Common sites include the calcaneal bursa near the hock, the bicipital bursa at the shoulder, and the bursae around the poll and withers.
This is more than a simple swelling. Once bacteria enter a bursa, inflammation and infected fluid can build quickly. That can cause pain, marked swelling, drainage, and lameness. In more serious cases, infection can extend into nearby tendon, bone, or other synovial structures, which makes treatment more involved and can affect long-term soundness.
Some horse people know infected bursae at the poll or withers by older names like poll evil or fistulous withers. Those terms describe location and appearance, but the urgent issue is the same: an infected synovial structure needs prompt veterinary care.
Symptoms of Septic Bursitis in Horses
- Sudden or progressive soft swelling over the hock, shoulder, poll, withers, or another pressure point
- Heat, pain, or marked sensitivity when the area is touched
- A wound, puncture, scab, or draining tract over the swelling
- Thick yellow, white, bloody, or foul-smelling discharge
- Lameness ranging from mild stiffness to severe non-weight-bearing pain
- Reduced range of motion or reluctance to flex the limb or lower the head
- Fever, dullness, reduced appetite, or other signs of systemic illness
- Swelling that returns quickly after being cleaned or bandaged
See your vet immediately if your horse has swelling over a bursa plus a wound, drainage, fever, or lameness. A tiny skin opening can hide a much deeper infection. Horses with infection near the hock, heel, shoulder, poll, or withers can worsen quickly, especially if bacteria have entered a synovial space. If your horse is painful, lame, depressed, or the area is actively draining, treat it as an emergency.
What Causes Septic Bursitis in Horses?
The most common cause is trauma that allows bacteria to enter the bursa. That may be a puncture wound, kick, scrape, wire cut, pressure sore, or another injury over a thinly covered area. The opening in the skin may look minor, but deeper structures can still be contaminated. This is especially important around the hock and heel, where penetrating wounds can involve the calcaneal bursa.
Some cases develop from repeated pressure or blunt trauma that first causes noninfectious bursitis, then becomes infected later if the skin breaks down. Poorly healing wounds, contaminated bandages, or delayed treatment can increase the risk. Infections around the poll and withers have historically been linked with conditions such as brucellosis, though that is uncommon in the United States.
Less often, infection may spread from nearby tissues or occur after a procedure involving a synovial structure. Your vet will also think about whether nearby tendon sheath, joint, or bone could be involved, because that changes both treatment planning and prognosis.
How Is Septic Bursitis in Horses Diagnosed?
Your vet usually starts with an urgent physical exam, wound assessment, and lameness evaluation. Location matters. Swelling over the point of the hock, shoulder, poll, or withers raises concern for bursal involvement, especially when there is heat, pain, or drainage. Because septic bursitis can look similar to a superficial abscess or cellulitis early on, deeper evaluation is often needed.
Diagnostics commonly include ultrasound to assess fluid pockets, soft tissue damage, and wound depth, plus radiographs to look for gas, foreign material, bone involvement, or chronic changes. If it is safe and appropriate, your vet may collect bursal fluid or discharge for cytology and bacterial culture. Bloodwork may help assess inflammation and overall health, particularly in horses with fever or more widespread illness.
In referral or surgical cases, advanced imaging, contrast studies, or bursoscopy may be recommended. These tests help confirm whether the infection is limited to the bursa or has spread to nearby tendon, bone, or another synovial structure. That distinction strongly affects treatment options, expected recovery time, and cost range.
Treatment Options for Septic Bursitis in Horses
Spectrum of Care means you have options. Here are treatment tiers at different price points.
Budget-Conscious Care
- Urgent farm or haul-in exam
- Sedation as needed for safe wound evaluation
- Basic wound clipping, cleaning, and bandaging
- Pain control and anti-inflammatory medication selected by your vet
- Systemic antibiotics chosen by your vet, often started before culture results if infection is strongly suspected
- Limited diagnostics such as basic ultrasound or a small set of radiographs when available
- Close recheck plan and strict stall or movement restriction as directed
Recommended Standard Treatment
- Urgent exam and full lameness/wound assessment
- Ultrasound and radiographs to define the affected bursa and check for foreign body or bone changes
- Sampling for cytology and bacterial culture when feasible
- More aggressive lavage, drainage, and repeated bandage care
- Systemic antibiotics adjusted to culture results when available
- Hospitalization or frequent rechecks for monitoring, bandage changes, and pain management
- Referral consultation if the wound appears to communicate with a synovial structure
Advanced / Critical Care
- Referral hospital care and advanced imaging as indicated
- Bursoscopy or surgical exploration with lavage and debridement
- Removal of foreign material or infected tissue when present
- Intensive IV medications, regional therapy, or repeated lavage procedures as directed by your vet
- Hospitalization for several days to a week or longer depending on response
- Management of complications such as osteomyelitis, tendon injury, or involvement of adjacent synovial structures
- Structured rehabilitation and follow-up imaging
Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.
Questions to Ask Your Vet About Septic Bursitis in Horses
Bring these questions to your vet appointment to get the most out of your visit.
- Do you think this swelling communicates with a bursa, tendon sheath, or joint?
- What diagnostics are most useful today: ultrasound, radiographs, fluid sampling, or referral imaging?
- Is there evidence of foreign material, dead tissue, or bone involvement?
- Which treatment options fit my horse's case right now: conservative care, hospital-based lavage, or surgery?
- What is the expected cost range for the next 24 to 72 hours, and what could increase that range?
- What signs at home would mean the infection is worsening or spreading?
- How often will bandages need to be changed, and what activity restriction is safest?
- What is the realistic outlook for comfort, healing time, and return to work in this specific location?
How to Prevent Septic Bursitis in Horses
Prevention starts with reducing trauma and treating wounds early. Check your horse daily for cuts, swelling, heat, or sore spots over the hocks, shoulders, poll, withers, and heels. Small punctures in these areas deserve extra attention because they can reach deeper structures. Clean fresh wounds as directed by your vet, keep bandages clean and dry, and avoid delaying an exam when swelling or drainage develops.
Good stable and pasture management also matters. Remove sharp wire, broken boards, exposed nails, and other hazards. Improve bedding and stall design if your horse rubs, lies on hard surfaces, or repeatedly bumps pressure points. Tack fit should be reviewed if your horse develops recurrent sores over the withers or shoulder region.
If your horse has a wound near a synovial structure, early veterinary assessment is the safest path. Prompt imaging and treatment can sometimes prevent a contaminated bursa from becoming a deep, established infection. For poll or withers swellings that recur or drain, your vet may also discuss testing for less common infectious causes based on your horse's history and region.