Strangles

We receive a lot of advice calls about strangles, particularly when there is an outbreak. There’s a lot of misinformation out there about this disease, adding to what is already very stressful for horse owners.

With this in mind we’ve put together a ‘Strangles Snapshot’, which covers essential background to the disease, management of affected horses and testing, in an easily accessible format. We hope you’ll find it useful, whether your horse has been affected or even just to know what to do if it is in your area.

Strangles snapshot (PDF 0.97MB)

Please don’t hesitate to get in touch directly or ask one of the team if you see them out and about. We can provide hard copy versions of these information sheets for your notice boards – just let us know and we’ll get them out to you.

Strangles background

Cause:

The bacterium Streptococcus equi.

Signs:

• Fever.
• Loss of appetite.
• Depression.
• Marked ‘snotty’ nasal discharge (the most common sign).
• Lymph node swelling and abscesses predominantly of the head and neck.
• NOT ALL HORSES SHOW ALL (OR ANY) of these signs.

Transmission:

• DIRECT (close contact with infected horse).
• INDIRECT (housing, water and feed buckets, tack and equipment, groom, instructor, farrier, vet or even other pets.

Reduce your risk:

Away from home

• Use your own buckets, water and feed.
• Do not allow other horses to share buckets.
• Avoid nose to nose contact with other horses.
• Wash your hands between horses when handling other horses.
• Disinfect your boots and outer clothing after each show.

At home

• Separate grooming kits, numnahs, rugs, tack and buckets for each horse.

Moving between yards

• Simple hygiene measures: wash hands, disinfect boots, changing outer clothing between yards.

New horses

• Three week isolation period (time for signs to develop before mixing with others).
• Consider blood test on arrival and at end of three weeks to identify previously infected and potentially infectious horses quickly and easily.
• Keep written records of horses entering and leaving premises.
• Even with perfect precautions, a horse may still become infected – some horses are carriers with no external signs of infection and can infect other horses.

Management

What to do if you suspect strangles. Without delay:

Isolate:

• ISOLATE the horse and any direct contacts (particularly nose-to-nose contact).
• ISOLATE indirect contacts (shared water and/or feed buckets, tack, handlers).
• ISOLATE away from other horses with which they have not had any contact.
• DO NOT allow other animals to enter the infected horse’s stable or to access its feed or water.

Call your veterinary surgeon:

• Call your vet for advice on management, sampling and lab strategies – is S. equi the likely cause of the signs?
• Take multiple samples from multiple horses or on multiple occasions from the same horse to confirm or exclude strangles.
• S. equi can be difficult to confirm and your vet will be able to advise.

If diagnosis is confirmed:

• Agree isolation and handling procedures and implement IMMEDIATELY.
• All horses to remain on the premises to protect other yards.
• Consider colour-coded groups:
  • RED – presumed infected: SIGNS of strangles (not ALL cases show ALL clinical signs);
  • AMBER – direct or indirect contact with infected horses: AT RISK but NO SIGNS;
  • GREEN – detached from RED and AMBER groups, NO KNOWN direct or indirect contact and NO SIGNS.
• Colour code equipment to prevent mixing and have dierent personnel look after each colour-coded group. If separate personnel not possible, personnel to move from lowest risk to highest risk, ie GREEN to AMBER to RED and NOT BACK AGAIN.
• No horses in or out of yard.
• Implement highest possible standards of hygiene.
• Monitor all horses in the yard: young, old and immunocompromised horses most susceptible.
• Check temperature of all horses daily – isolate any with increase in temperature (moved to RED group) to be seen by vet.
• Notify neighbouring premises with horses – they should monitor their horses the same way and seek vet advice.

Testing

Release from isolation:

No presumed affected horse in the RED group to be released from isolation or removed from vet supervision until:

• Negative guttural pouch wash
  OR
• Three consecutive negative weekly nasopharyngeal swabs

Nasal swabs are less effective, so endoscopically-guided guttural pouch wash is preferred.

In horses with clinical signs this testing cannot be started until three weeks after last signs.

Samples will be tested by BOTH culture and PCR (Polymerase Chain Reaction) to maximize sensitivity and to avoid positive horses testing negative.

Yard not to re-open normally until after all horses are confirmed uninfected.

Animals testing positive for S. equi remain isolated until they are negative – this may require treatment for persistent infection of the guttural pouches.

Carriers:

Screen horses in the AMBER and GREEN groups by blood test a minimum of 10 days after last exposure to identify carriers – if left untreated they could trigger subsequent outbreaks.

Positive blood tests should prompt isolation and investigation by guttural pouch wash or nasopharyngeal swabs. As above, washes are preferred.

Carriers identified need to remain in isolation until negative, which may require treatment appropriate for persistent infection of the guttural pouches. This involves removing chondroids (chunks of pus from abscesses in the guttural pouch) and antibiotics, followed by guttural pouch wash to confirm infection-free status.