Understanding Equine Strangles
Christina L. Garloff, DVM
Equine Veterinary Associates, Inc.
History
First reported in 1251Highly contagious
Young horses most commonly affected
Recurrence at farm commonMost commonly diagnosed contagious disease worldwideCause
Bacterial infection with Streptococcus equi subspecies equi (S. equi)
Location Usually affects the upper airway and lymph nodes of the head & neck,
but can be seen in other portions of the body
Clinical Signs Common:
Fever (> 101.5°F) Anorexia, depression, difficulty swallowing Nasal discharge Enlarged submandibular lymph nodes Purulent nasal discharge
Less common Enlarged retropharyngeal lymph nodes
Guttural pouch infection-Empyema Enlarged lymph nodes on other portions of the head
Complications Most recover without complication Infection in other parts of the body
Metastatic infection or Bastard Strangles Strangulation of airway
Tracheostomy Immune mediated disease
Purpura Hemorrhagica Muscle disease Decreased milk production in mares
Transmission
Nasal/abscess discharge from infected horse Days to weeks
Nasal discharge from asymptomatic carrier Months to years
Contaminated environment Water-over 1 month, ground/bedding variable
Contaminated equipment &/or handlers Buckets, feed tubs, grooming equipment, stall cleaning supplies, tack, clothing, other
animals
Diagnosis
Clinical signs highly suggestive Culture of discharge PCR nasal swab
Start shedding a few days after fever onset Intermittent for several weeks
4-50% of horses on recurrent farms are carriers Months to years
Blood titer-rise in levels when infected
Treatment Antibiotic therapy remains controversial
Needed for complicated cases Anti-inflammatories for pain/fever Hot pack affected area
+/- drawing agent (Ichthammol, etc.) Surgically lance when mature
Soft feed if throat is sore Isolation from other horses!!
Outbreak Management Horse movement in and out of stable should stop Monitor temperatures twice daily Isolate at first sign of fever
Contagious 1-2 days after fever begins
Outbreak Management
Create three separate groups Clean horses with no exposure
Separate area & separate caretakers & equipment Daily care should be first
Exposed horses Infected horses
Outbreak Management Infected horses
Use protective clothing Care for last Use dedicated equipment Thoroughly disinfect equipment
between horses Thoroughly disinfect hands and
shoes between horses Disinfect water buckets daily Waste from infected horses should
be isolated & disposed of separately Rest exposed turn-outs/arenas
minimum of 4 weeks Three consecutive negative PCR
swabs (at least one week apart) for each horse before returning to general population
Vaccination Does not guarantee disease prevention
Intramuscular route High rate of vaccine reactions Approx 60% effective
Intranasal route Current recommended vaccine Initial 2 doses, 2-3 weeks apart-protected 1 month after second
dose, annual booster
Not recommended during an outbreak Recovered horses often develop immunity for 1 year
or more
Preventative Measures Require current health certificates for all new horses Obtain Strangles history/require negative PCR test before allowing on property
Consider vaccination requirement before arrival Quarantine new horses for a minimum of 3 weeks before allowing in general population
Monitor temp daily Each horse should have a dedicated water bucket that is disinfected regularly Minimize exposure to other horses/supplies at shows Pastured horses should be grouped by age & risk level
Questions?
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