Necrotic Vaginitis in Horses and Donkeys After Foaling: Signs, Treatment, and Recovery

By Dr Duncan Houston

A mare can deliver a live foal and still have significant internal trauma.

That is why some of the most important post-foaling problems are missed in the first 12 to 24 hours. The delivery is over, the foal is nursing, and everyone relaxes. But inside the birth canal, bruised or devitalised tissue may already be progressing toward necrosis.

Necrotic vaginitis is one of the more serious postpartum injuries seen in mares, and it deserves more attention than it often gets. It is especially important in maiden mares, difficult foalings, miniature horses, and donkeys, where tissue trauma and swelling can be more severe and healing complications more likely.

The goal is not just to treat infection. It is to identify tissue damage early, protect healing tissue, prevent adhesions, and preserve future reproductive function.

Quick Answer

Necrotic vaginitis is tissue death in the vaginal lining after foaling trauma. It is most likely after difficult births, first foalings, and in miniature horses or donkeys. Early vaginal examination, prompt treatment, and careful follow-up are critical because delayed care can lead to infection, painful healing, adhesions, and long-term reproductive damage.

What Is Necrotic Vaginitis?

Necrotic vaginitis is damage to the vaginal lining severe enough that tissue loses its blood supply and begins to die.

This usually starts with:

• bruising

• compression

• tearing

• swelling after foaling trauma

If that tissue becomes devitalised, it can progress from inflammation to necrosis, sloughing, infection, and scarring.

This is not the same as mild postpartum soreness. Mild trauma is common. Necrotic vaginitis is a more serious injury with real long-term consequences if it is missed.

Why It Happens After Foaling

The vaginal tissues are stretched and compressed during birth. That alone can cause mild trauma, especially in larger foals or prolonged deliveries.

Risk rises sharply when there is:

• dystocia or difficult foaling

• prolonged second stage labour

• assisted extraction or obstetrical manipulation

• first-time foaling

• narrow pelvic conformation

• small maternal size relative to foal size

Horses at higher risk

• maiden mares

• miniature mares

• donkeys

• mares with difficult or assisted deliveries

Clinical insight

The most dangerous cases are not always the most dramatic at the time of foaling. Some mares look only mildly uncomfortable early on, while significant tissue injury is already developing.

Why Miniature Horses and Donkeys Need Special Attention

Miniatures and donkeys are overrepresented in these cases for practical reasons.

They often have:

• less room for delivery

• more soft tissue compression

• greater risk of local swelling and tearing

• higher risk of adhesions during healing

In smaller patients, even modest trauma can cause major narrowing, tissue damage, and scar formation. That is why a problem that begins as bruising can become a breeding or future foaling issue if follow-up is poor.

What Does Necrotic Vaginitis Look Like Early?

Early signs are often nonspecific, which is why owners and breeders can miss it.

You may see:

• lethargy

• reduced appetite

• discomfort around the tailhead or vulva

• frequent attempts to urinate

• dribbling urine

• straining

• reluctance to move

• tail swishing or signs of hindquarter pain

Some mares are simply quieter than expected after foaling. Others appear sore when urinating or when the hindquarters are handled.

Decision checkpoint

If a mare seems more painful, dull, or irritated than expected after foaling, especially after a difficult delivery, that should not be dismissed as routine postpartum soreness.

When Should You Suspect Significant Birth Canal Trauma?

Suspicion should be high if:

• the foaling was difficult

• traction or internal manipulation was needed

• the mare is a maiden

• the mare is a miniature or donkey

• there is urinary dribbling

• the mare remains depressed beyond the immediate post-foaling period

• there is visible vulvar swelling, bruising, or discharge

The key question is not whether the foal was delivered successfully. The key question is what the birth canal looks like afterward.

How Vets Confirm the Diagnosis

A proper post-foaling reproductive examination is what changes this from guesswork to real medicine.

Vaginal Examination

A speculum exam is the most important next step when trauma is suspected.

This allows visual assessment of:

• bruising

• swelling

• tearing

• tissue colour

• early sloughing

• involvement near the urethral opening

What tissue colour can mean

• red, inflamed, or bruised tissue suggests early trauma and inflammation

• dark purple, blue, grey, or black tissue raises concern for devitalisation and necrosis

This exam should be done gently and carefully. In some cases, sedation and pain control may be needed.

Additional Examination

Depending on the case, a veterinarian may also perform:

• rectal examination

• transrectal ultrasound

• transabdominal evaluation

• assessment for deeper tears or associated reproductive trauma

Clinical insight

The real value of early examination is not just diagnosis. It is catching tissue before it progresses from bruised to necrotic.

The 12 to 24 Hour Window Matters

This is one of those postpartum problems where timing changes the outcome.

A mare examined early may have:

• bruising

• swelling

• localised trauma
  that can be managed before tissue breakdown progresses.

A mare examined late may already have:

• necrotic tissue

• secondary infection

• painful sloughing

• adhesion formation

Practical rule

Any mare with a difficult foaling should be assessed within 12 to 24 hours. In miniatures and donkeys, that recommendation becomes even more important.

Severity Framework: How Worried Should You Be?

Mild

• mild bruising

• normal appetite

• no urinary issues

• minimal discomfort

What it usually means:
Superficial trauma only

What to do:
Monitor closely and follow veterinary guidance. Recheck if signs progress.

Moderate

• visible bruising or swelling on vaginal exam

• reduced appetite

• discomfort when urinating

• mild depression

What it usually means:
Significant tissue injury with risk of progression

What to do:
Veterinary treatment and follow-up are warranted. This should not be left to watch-and-wait alone.

Severe

• dark, devitalised, or necrotic tissue

• foul discharge

• marked pain

• persistent urinary signs

• worsening demeanour

What it usually means:
Established necrotic vaginitis with high risk of infection and scarring

What to do:
Prompt treatment is required, with ongoing reassessment.

High Risk for Future Fertility Problems

• miniatures

• donkeys

• extensive trauma

• delayed treatment

• adhesion formation

What it usually means:
The injury may heal, but not necessarily heal well unless managed properly.

When Is This an Emergency?

Treat this as urgent if a postpartum mare has:

• marked depression

• fever

• refusal to eat

• significant straining

• foul-smelling discharge

• severe vulvar or hindquarter pain

• worsening swelling

• signs of systemic illness

• inability to urinate normally

These signs raise concern not just for necrotic vaginitis, but for broader postpartum complications including deeper trauma, infection, or urinary tract involvement.

Treatment of Necrotic Vaginitis

Treatment depends on severity, but the principles are consistent.

The goals are to:

• control bacterial contamination

• reduce inflammation

• protect damaged tissue

• support healing

• prevent adhesions

• preserve future reproductive function

1. Control Infection

Systemic antibiotics are often used where there is significant tissue damage, contamination, or developing infection.

The exact drug choice depends on:

• severity

• contamination risk

• tissue appearance

• systemic signs

• veterinary judgement

This is not a condition where random antibiotic use is helpful. Drug choice and duration should be based on the case in front of you.

2. Reduce Inflammation and Support Healing

Topical therapy may be used to protect tissue and reduce inflammation. In suitable cases, a veterinarian may apply an antibiotic and anti-inflammatory preparation directly to the damaged vaginal lining.

The purpose is not cosmetic. It is functional:

• limit secondary infection

• reduce pain and irritation

• improve tissue recovery

• reduce the risk of opposing surfaces sticking together during healing

3. Prevent Adhesions

This is one of the biggest long-term concerns, especially in miniature mares.

When inflamed, raw tissue surfaces heal against each other, fibrous adhesions can form. These adhesions may:

• narrow the vaginal canal

• interfere with breeding

• complicate future foaling

• create chronic reproductive problems

This is why follow-up and repeated reassessment matter. The treatment plan is not finished once medication starts.

4. Recheck Healing Progress

These mares need monitoring until healing is clearly progressing in the right direction.

That may include:

• repeat vaginal examinations

• reassessment of tissue colour and integrity

• checking for discharge, pain, and adhesion formation

• reviewing appetite, demeanour, and urination

Clinical insight

The biggest mistake is assuming improvement on the outside means healing is complete on the inside.

What Should You Do Right Now If You Suspect It?

If a mare has foaled recently and you are concerned about trauma:

1. Do not assume postpartum soreness is normal if signs are persistent or worsening.

2. Check whether the mare is eating, bright, and urinating normally.

3. Note any urinary dribbling, straining, discharge, or hindquarter pain.

4. Arrange a veterinary examination promptly, especially after a difficult birth.

5. Do not attempt internal treatment yourself unless directly instructed by your veterinarian.

Time-based guidance

If the mare is dull, off feed, or painful in the first 12 to 24 hours after foaling, do not wait several days to see if it settles.

Common Mistakes Owners Make

Waiting because the foal is fine

A healthy foal does not rule out serious maternal trauma.

Assuming all postpartum discomfort is normal

Some soreness is expected. Persistent pain, depression, or urinary signs are not.

Skipping the post-foaling exam after a difficult delivery

This is how early traumatic lesions get missed.

Focusing only on infection

The problem is not just bacteria. It is tissue injury, tissue viability, and healing pattern.

Underestimating adhesion risk in miniatures

This is one of the most important long-term reproductive concerns in these patients.

Can It Affect Future Fertility?

Yes, it can.

If damage is severe or healing is poor, mares may develop:

• scar tissue

• adhesions

• narrowing of the vaginal canal

• breeding difficulties

• increased risk in future foalings

This is why early treatment is not just about comfort. It is about reproductive preservation.

Practical takeaway

The earlier significant trauma is identified, the better the chance of healing without permanent functional damage.

Prevention: What Reduces the Risk?

Not every case can be prevented, but risk can be reduced by:

• good foaling supervision

• early recognition of dystocia

• prompt veterinary assistance during difficult births

• routine postpartum examination after assisted foaling

• low threshold for internal examination in miniatures and donkeys

Prevention here is really about early detection and good obstetrical management.

Frequently Asked Questions

Is necrotic vaginitis the same as a simple vaginal tear?

No. A tear may be present with or without necrosis. Necrotic vaginitis specifically refers to tissue death after trauma.

Can a mare look normal at first and still have serious trauma?

Yes. Some mares show only subtle signs early on.

Why do urinary signs happen?

Trauma often affects tissue near the urethral opening, causing pain, irritation, swelling, and altered urination.

Are miniature mares at higher risk?

Yes. They are at greater risk of trauma and adhesion-related complications.

Will this always affect future breeding?

No. Many mares recover well if the injury is identified and managed early.

Final Thoughts

Necrotic vaginitis is one of those postpartum complications that can be easy to miss and difficult to fix once delayed.

The important point is simple: a successful foaling does not guarantee an undamaged mare.

If there has been trauma, the job is not done when the foal is born. The next step is making sure the mare heals properly, without infection, adhesions, or long-term reproductive consequences.

That is why early examination matters so much.

If there is any doubt about how a mare is recovering after foaling, especially after a difficult delivery or in a miniature or donkey, ASK A VET™ can help guide the next steps and clarify when urgent examination is needed.