1. Understanding Equine StranglesChristina L. Garloff, DVMEquine Veterinary Associates, Inc.
2. HistoryFirst reported in 1251Highly contagious Young horses most commonly affectedRecurrence at farm commonMost commonly diagnosed contagious disease worldwideCause 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
3. 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
4. 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
5. 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, otheranimals
6. 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
7. 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!!
8. 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
9. 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
10. Outbreak Management Infected horses Use protective clothing Care for last Use dedicated equipment Thoroughly disinfect equipmentbetween horses Thoroughly disinfect hands andshoes between horses Disinfect water buckets daily Waste from infected horses shouldbe isolated & disposed of separately Rest exposed turn-outs/arenasminimum of 4 weeks Three consecutive negative PCRswabs (at least one week apart) foreach horse before returning togeneral population
11. 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 aftersecond dose, annual booster Not recommended during an outbreak Recovered horses often develop immunity for 1 yearor more
12. 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