Presented by Dr. Robert Hunter
Also known as: Dryland Distemper, Ulcerative Lymphangitis, Caseous Lymphadenitis, Equine Acne, Pigeon Breast
Etiologic Agent: Bacteria, Corynebacterium pseudotuberculosis
Mode of Infection:
- Through skin or mucous membranes
- Skin abrasions
- Biting insects (flies, gnats)
Seasonality:
- July through January
- External abscesses mostly Sept, Oct, Nov
- Repeat/Internal abscesses mostly Nov, Dec, Jan
- Recurrence/Internal abscessation usually within 3-6 months
Symptoms and Clinical Signs:
- External abscesses: chest, sheath, udder, ventral abdomen, side of face, neck, shoulder, hip
- Lameness
- Rupture with drainage or just oozing of serum (thick, caseous, white pus; non-odorous)
- +/- fever and +/- anorexia (loss of appetite)
- listless
- Internal abscesses = fever, lethargy, anorexia, weight loss, abdominal pain, abortion, increased heart rate, increased respiratory rate (30% fatal, 100% fatal if not treated)
Diagnosis:
- Clinical signs
- Bacterial culture of pus
- Ultrasound
- Serum titers ≥ 512
- PCR genetic testing
- Basic blood work
Treatment:
- Lance/flush abscesses whenever possible
- Hot packs, poultice
- Antibiotics +/- (internal abscesses require long-term)
- Anti-inflammatories
- Immune Stimulants
Prevention:
- No vaccine!
- Fly control
- General environmental cleanliness
- Varying levels of immunity:
- No infection
- Lymph node abscesses
- Multiple abscesses
- Internal abscesses
Endemic in certain areas – new horses, young horses, aged horses, and immune compromised horses are at the greatest risk.
Contagion:
- Not contagious in the typical ways
- Does not transfer horse to horse
- Fly bites occur in summer & may take weeks/months to show clinical symptoms
- May show up all of a sudden – swelling, pain, etc.
