Animal health brief

STRANGLES

IN THIS NEW SERIES, WE’RE GOING TO COVER SOME COMMON DISEASES THAT AFFECT THE EQUINE POPULATION; HOW TO SPOT THEM, MEASURES TO PROTECT HORSES, AND HOW TO PREVENT TRANSMISSION. IN PART ONE, WE LOOK AT STRANGLES – A HIGHLY CONTAGIOUS UPPER RESPIRATORY TRACT INFECTION, WHICH AS ITS NAME SUGGESTS CAN RESULT IN COMPRESSION OF THE HORSE’S THROAT.

Streptococcus equi subspecies equi is responsible for strangles. The bacteria often infect lymph nodes around the jaw, causing swelling and di culty breathing.

Whilst fatalities are rare, strangles can still be painful and debilitating. It’s one of the most challenging equine infectious diseases to manage.

WHAT ARE THE SIGNS?

Vary from mild e.g. slight nasal discharge to these more typical signs: • Depression • Loss of appetite/ di culty eating • Raised temperature • Cough • Nasal discharge, often thick and yellow • Swollen lymph nodes around throat • Drainage of pus from lymph nodes around jaw Incubation is between three and 14 days and most recover within six weeks. Roughly 10% remain carriers and can still transmit the disease.

COMPLICATIONS

Occasionally, abscesses will develop within other organs. This is known as ‘bastard strangles’ and can be fatal. Another rare and potentially fatal complication is ‘purpura haemorrhagica’ which causes bleeding from the capillaries and fl uid accumulation in and around the limbs and head.

DIAGNOSIS

Strangles can be diagnosed on clinical signs alone but often vets will take a nasopharyngeal swab for confi rmation. lood samples may be taken to identify not only infected horses but also carriers. Another method is guttural pouch endoscopy. Your vet will advise the most appropriate method.

TREATMENT

Supportive care involving anti-infl ammatories to lower temperature. Feeding sloppy food from the fl oor makes it easier for infected horses to swallow and encourages abscesses to drain. Hot compresses help them to rupture. Occasionally, vets use antibiotics. It’s imperative to isolate the infected horse.

Treatment for carriers involves removal of dried pus from guttural pouches via endoscopy and the use of topical antibiotics within the pouches.

HOW CAN IT BE PREVENTED?

Strangles is endemic within the UK and relatively common. Outbreaks cause disruption and economic problems. It’s highly contagious and spreads via direct contact or indirectly through equipment, shared drinking water and clothing. The bacteria can survive for up to four weeks. • Ensure the yard isn’t overcrowded. • Avoid sharing tack or equipment from horses of unknown health. • At shows/away from the yard, avoid contact with horses of unknown health. Take your own buckets, water and equipment. • Ensure new arrivals are kept apart from others (at least 10 metres) for at least two weeks. • Consult your vet for advice on a strangles vaccination policy for the yard. Some yards insist horses are tested before arrival to identify carriers.

MANAGEMENT DURING AN OUTBREAK

1. Isolate the affected horse at least 10 metres (ideally 25) away from others, with own equipment and water source. Handlers mustn’t move between the infected horse and others. 2. Seek advice from the vet about management, treatment and testing. 3. Lock down yard to prevent horses entering or leaving. 4. Divide horses into groups which mustn’t mix: a. Red – clinical signs and raised temperature. b. Amber – horses which were in contact with horses from red group, even if indirect. c. Green – no known contact with either of above. 5. Healthy horses – monitor temperature twice daily. 6. Foot dips and separate clothing/equipment should be available for each group. 7. Notify all owners. 8. No horse should leave the red area until three consecutive negative nasopharyngeal swabs or a single negative guttural pouch wash is taken. 9. Green and amber groups tested to ascertain infection or carrier status. ■