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Published Date: 2013-05-21 11:23:08
Subject: PRO/AH/EDR> Strangles, equine - Australia: (02): (NS, AC)
Archive Number: 20130521.1727081

STRANGLES, EQUINE - AUSTRALIA (02): (NEW SOUTH WALES, AUSTRALIAN CAPITAL TERRITORY)
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Date: Mon 20 May 2013
Source: Cowra Guardian [edited]
http://www.cowraguardian.com.au/story/1511311/horse-owners-on-alert-after-disease-outbreak/?cs=591


An outbreak of the contagious disease 'strangles' has affected horses throughout areas of NSW [New South Wales] and the ACT [Australian Capital Territory] recently. Strangles is a contagious bacterial disease in horses that affects the upper respiratory system and lymph nodes of the head, making eating and drinking very painful.

The Nationals Member for Burrinjuck and Minister for Primary Industries, Katrina Hodgkinson is urging local horse owners to ensure their horses' immunisations are up to date.

"Strangles can be distressing for the animal and particularly young horse owners so making sure your vaccinations are up-to-date is a simple measure that can prevent or lessen the impact of this disease," she said.

Veterinary nurse Danielle Tysoe from Cowra Veterinary Centre said while there haven't been any reported cases in the Cowra region as of yet she would encourage all horse owners, particularly those with competition horses and broodmares to vaccinate against the disease.

"People in this area are generally very good at vaccinating, particularly those with competition horses who have interaction with other horses at shows and camp drafts," she said.

"Competition horses can be vaccinated against strangles every 6 months and breeding mares should also be done every 6 months.

"Ms Tysoe said young horses can be vaccinated against strangles from 3 months of age with 3 doses, 2 weeks apart. Jenny Bryant, mother of local dressage and eventing [horse trials] competitor Megan Bryant said a competition in Canberra was recently cancelled due to concern over the outbreak. With Megan competing at top level, Mrs Bryant said the health of their horses is paramount. "They're all vaccinated against strangles as foals," she said. "With the amount of contact they have with each other, you just can't not vaccinate.

"Signs of strangles include a fever, swollen lymph nodes in the head and throat area, a watery nasal discharge, which in some cases is accompanied by a cough.

Strangles is a notifiable disease and any cases or suspected cases must be reported to a vet or the Department of Primary Industries.

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[Strangles is an infectious, contagious disease of Equidae characterized by abscesses in the lymphoid tissue of the upper respiratory tract. The causative organism, _Streptococcus equi equi_, is highly host-adapted and generally produces clinical disease only in horses, donkeys, and mules. It is a Gram positive, capsulated-hemolytic Lancefield group C streptococcus, which is an obligate parasite and a primary pathogen.

_S. equi equi_ is highly contagious and produces high morbidity and low mortality in susceptible populations. Transmission occurs via fomites and direct contact with infectious exudates. Carrier animals are important for maintenance of the bacteria between epizootics and initiation of outbreaks on premises previously free of disease. Survival of the organism in the environment is dependent on temperature and humidity; it is susceptible to desiccation, extreme heat, and exposure to sunlight, and must be protected within mucoid secretions to survive. Under ideal environmental circumstances, the organism can survive 7-9 weeks outside the host. Paddocks and barn facilities used by infected horses should be regarded as contaminated for about 2 months after resolution of an outbreak.

The incubation period of strangles is 3-14 days, and the 1st sign of infection is a fever of 103-106 deg F [39.4-41.1 deg C]. Within 24-48 hours of the initial fever spike, the horse will exhibit signs typical of strangles, including mucoid to mucopurulent nasal discharge, depression, and submandibular lymphadenopathy. Horses with retropharyngeal lymph node involvement will have difficulty swallowing, inspiratory respiratory noise (compression of the dorsal pharyngeal wall), and extended head and neck. Older animals with residual immunity may develop an atypical or catarrhal form of the disease with mucoid nasal discharge, cough, and mild fever. Metastatic strangles ("bastard strangles") is characterized by abscesses in other lymph nodes of the body, particularly in the abdomen and, less frequently, the thorax.

The environment for clinically ill horses should be warm, dry, and dust-free. Warm compresses are applied to sites of lymphadenopathy to facilitate maturation of abscesses. Facilitated drainage of mature abscesses will speed recovery. Ruptured abscesses should be flushed with diluted (3-5 percent) povidone-iodine solution for several days until discharge ceases. NSAID [non-steroidal anti-inflammatory drugs] can be administered judiciously to reduce pain and fever and improve appetite in horses with fulminant clinical disease. The affected horses are quite uncomfortable.

Antimicrobial therapy is controversial. Most authors agree that initiation of antibiotic therapy after abscess formation may provide temporary clinical improvement in fever and depression but ultimately prolongs the course of disease by delaying maturation of abscesses. Antibiotic therapy is indicated in cases with dyspnea, dysphagia, prolonged high fever, and severe lethargy/anorexia [loss of appetite]. Administration of penicillin during the early stage of infection (up to 24 hours after onset of fever) will usually abort abscess formation. The disadvantage of early antimicrobial treatment is failure to mount a protective immune response, rendering horses highly susceptible to infection after cessation of therapy. If antimicrobial therapy is indicated, procaine penicillin (22 000 IU/kg, intramuscular injection, twice a day) is the antibiotic of choice. Sharing of halters and brushes that may contact the fluid from draining abscesses can spread the disease to other horses. Those affiliated with the government veterinary office are quite conscious of biosecurity and are able to assist the track veterinarian and the owners with proper methods to avoid spreading the disease.

Portions of this comment were extracted from http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/121309.htm&word=strangles.

New South Wales and Australian Capital Territory may be seen on the maps below
- Mod.TG

A HealthMap/ProMED-mail map can be accessed at: http://healthmap.org/r/1oP3, http://healthmap.org/r/5Zdr.]

See Also

Strangles, equine - Australia (AC, NS) 20130509.1700512
2012
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Strangles, equine - UK: (Scotland) 20130413.1643643
Strangles, equine - Chile: (BI) 20120606.1157584
Strangles, equine - USA (NY) 20120324.1079901
2011
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Strangles, equine - USA: (MI) 20110911.2764
Strangles, equine - UK (02): (Scotland) 20110806.2371
Strangles, equine - UK: (Guernsey) 20110303.0693
Strangles, equine - Canada: (PE) 20110213.0489
2010
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Equine strangles - Australia (02): (NS) 20100606.1881
Equine strangles - Australia: (QL) 20100428.1361
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