Revised:  07/09/2008

Memo for March 31, 2005













New Jersey Department of Agriculture, Division of Animal Health



To: Small and Large Animal Practitioners

From: State Veterinarian Nancy E. Halpern, DVM

Date: March 31, 2005

Re: Streptococcus equi (Strangles)


     In the past couple of months, a small number of Streptococcus equi (aka Strangles) cases have been identified within the thoroughbred racing community of southern Florida and Kentucky. Isolation, quarantine, treatment, and preventative measures have been implemented within these facilities. In response to these cases, several racing facilities have imposed restriction upon entrance. The New Jersey Department of Agriculture (NJDA) would like to remind everyone that Streptococcus equi is a ubiquitous organism that frequently occurs during the show and racing seasons. While the NJDA does not feel these cases warrant bans predicated on the horse’s origination, the following recommendations should be implemented to prevent and control disease outbreaks:

  • Horses exhibiting clinical signs S. equi infection should not be permitted entry onto the premises.
  • Horses having been exposed to other horses with S. equi infection within the past 6 weeks should have a negative culture or PCR from a nasal swab or wash in the past 2 weeks time prior to entry on the premises.
  • Horse’s rectal temperature should be normal prior to entry.
  • Isolate newly introduced animals for two weeks and observe for signs of strangles or other diseases.
  • Immediately quarantine affected or suspect cases.
  • Practice good biosecurity techniques.

     Strangles is a highly contagious disease caused by the bacterium Streptococcus equi that is found throughout the United States. Transmission of the bacteria from horse to horse usually involves direct face-to-face contact or exposure of horses to contaminated feed, water, hands, leads, halters, veterinary instruments, grooming tools and twitches. The disease can also be acquired from exposure to a contaminated environment as long as the organism remains viable. However, a dry environment quickly kills the bacteria.


     Strangles is characterized by sudden onset of fever, loss of appetite, painful swallowing, drooling, swellings associated with the throat region, below the jaw, and the base of the ear, nasal discharge, cough and abscess formation. Horses usually develop fevers 3-14 days after exposure and nasal shedding 2-3 days after the onset of pyrexia. Nasal shedding can persist for up to 2-3 weeks, making isolation of horses with fevers a potential key to limiting the spread of the disease on a farm. A recovered horse may be a potential source of infection for at least 6 weeks after its clinical signs of strangles have resolved. Subclinical S. equi carriers remain a potential long-term source for susceptible horses as well as the reason for new outbreaks.


     Although the clinical diagnosis of Strangles is fairly straightforward, a definitive diagnosis is imperative for surveillance, quarantine measures, and the control of the disease. The Division of Animal Health Laboratory will culture for strangles at no charge. Sample submission is extremely important in culturing S. equi. Satisfactory specimens include nasopharyngeal culture, trans-tracheal wash, pus from an abscess, nasal discharge or nasal flushes. Swabs are of value in transporting the material to the lab. However, Streptococcus is easily dried out during shipment, making it advisable to place swabs in a non-nutritional transport media (Amies, Amies with charcoal, or Stuarts’s) and ship them rapidly. Laboratory identification will take between 48 and 72 hours, while confirmatory tests require an additional 24 hours.


     For further information, please consult the American College of Veterinary Internal Medicine’s Consensus Statement at


     If you have any further questions or concerns do not hesitate to contact the New Jersey Department of Agriculture at (609) 292-3965.


Website: New Jersey Department of Agriculture, Division of Animal Health






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