Parrott Equine Associates, LLC.

General Recommendations for the Management of Streptococcus Equi var. Equi (Strangles) Outbreak:

Definition: Streptococcus equi is the etiologic agent for the upper respiratory disease commonly referred to as Strangles. Less commonly, the bacteria may affect lymph nodes in the thorax and/or abdomen, causing a syndrome known as metastatic Strangles. Comprehensive information is available in the ACVIM Consensus statement, �Streptococcus equi Infections in Horses: Guidelines for Treatment, Control and Prevention of Strangles�, Corrine R. Sweeney, John F. Timoney, J. Richard Newton, and Melissa T. Hines, J Vet Intern Med 2005;19:123-134.
Click here for link to ACVIM document:

Clinical Signs: The horse may exhibit the following:

Fever, usually preceding other clinical signs by 24-48 hours
Lymphadenopathy +/- abscessation (retropharyngeal and submandibular lymph nodes most commonly involved)
Mucopurulent nasal discharge
Pharyngitis
Dysphagia (Difficulty Swallowing)
Upper airway stridor (Noise)
Clinical signs are age related, with older horses typically exhibiting milder signs of shorter duration.

Incubation: 3-14 days shorter interval reflects exposure to larger bacterial challenge

Transmission: Transmission may occur by direct or indirect horse contact.

Direct: horse-to-horse contact
Indirect: fomites (eg: person-to-horse contact and horse drinking/eating from contaminated common source)

Diagnostic Testing:

PCR	In combination with culture is test of choice determine the status of exposed and recovered animals More sensitive than culture to small amounts of bacterial DNA but does not differentiate live bacteria from dead False negative: PCR can be inhibited in presence of large amounts of mucopurulent debris
Bacterial culture	Diagnostic test of choice for clinically affected horses. Samples collected early in the course of clinical disease may yield negative results on culture. If signs are consistent with Strep equi infection, repeat testing at weekly intervals. If several animals are affected, submit single samples from as many animals as possible.
Sample collection:	Nasopharyngeal wash and nasopharyngeal swab

Shedding Time of Organism Past Resolution of Clinical Signs: Typically, 2-3 weeks post-recovery but intermittent shedding may occur for months to years when bacteria persists in guttural pouches or paranasal sinuses. Endoscopic examination and sampling (for culture and PCR) of the guttural pouches is warranted in detection of persistent infection. Absent of diagnostic testing to detect chronic shedders, horses should be considered infective for up to 6 weeks post -infection.

Specific Control and Treatment Measures: Reports of environmental viability vary widely.

Aggressive cleaning and disinfection, with special attention to the cleaning and disinfection of water containers, feeders, fences, stall walls and trailers, is indicated.
It is recommended that pastures and paddocks be rested at least 30 days.
Strict isolation of affected animals from healthy ones.

Guidelines for Monitoring Disease: Disease surveillance

Recording rectal temperatures twice daily with segregation and initiation of testing on any horse developing fever > 102.5o F (39o C) or clinical signs.

Clinically normal horses housed within the primary perimeter may be permitted segregated exercise periods outside the perimeter. Precautions should be taken, and may include:

Exercise scheduled after general population�s exercise.
Direct horse-to-horse contact is to be avoided
Prompt post-contact use of hand sanitizer by individuals having contact with horses during exercise

Release of Animals: To minimize the risk that recovered horses may pose, 3 consecutive weekly PCR and culture by nasopharyngeal wash are recommended. Should one of these tests result in a positive, it is advisable that further diagnostic investigation be performed to locate the focus of persistent infection. Treatment, with subsequent retesting, is appropriate. For animals having been housed within the secondary perimeter: Release testing is unnecessary in clinically normal horses having no history of exposure, and having had normal rectal temperature for 21 days.

Biosecurity Management for Receipt of Animals: Requirements for accepting animals are determined after identifying �acceptable level of risk� for the recipient facility. Given the mobility of populations involved in showing/racing/competition, exposure risk cannot be completely eliminated. The following options may be considered:

For horses having been housed within primary perimeter:
3 consecutive weekly nasopharyngeal lavage samples tested by PCR and culture with negative results

Single negative PCR/culture is of little value as a stand-alone indicator of risk, and must be evaluated in the context of exposure history.

Paraphrased from AAEP 2008 Guidelines