Once infected your horse will appear depressed, dull, and will stop eating.

Symptoms can include:

• A sudden high temperature, typically the temperature rises to 41°C
• Inflammation of the lymph nodes
• Nasal catarrh and often coughing
• After a few days the lymph nodes around the throat swell, forming abscesses
• Your horse will have difficulty breathing and swallowing (hence the name strangles)

If left untreated the lymph node abscesses will usually burst and drain but in extreme cases the abscess can become so large they can crush the windpipe and result in strangulation of the horse.

A nasal discharge appears and is initially clear but then becomes purulent (thick with signs of pus), after the abscesses have ruptured in the nasal passages.

Abscesses that rupture shed highly infective pus into the environment, which can infect other horses.

The main and often fatal complications of strangles are:

Bastard strangles :

Which describes the spread of infection to unusual sites within the body other than the lymph nodes draining the throat. For example; abdominal or lung lymph nodes may develop abscesses and rupture, sometimes weeks or longer after the infection seems to have resolved. A brain abscess may rupture causing sudden death or a retropharyngeal lymph node abscess may burst in the throat and the pus will be inhaled into the lung.

Purpura haemorrhagica :

Is an immune-mediated acute inflammation of peripheral blood vessels that occurs within 4 weeks of strangles, and while the animal is convalescing. It results from the formation of immune complexes between the horses antibodies and bacterial components. These immune complexes become trapped in capillaries where they cause inflammation, visible in the mucous membranes as pinpoint haemorrhages. These haemorrhages lead to a widespread severe edema of the head, limbs, and other parts of the body. Purpura can also be a complication of routine vaccination

Minor, non-fatal complications include:

Post strangles myocarditis -
(inflammation of heart muscle), which may follow strangles in a small proportion of horses. An electrocardiogram (ECG) can determine that a horse can return to heavy work or to training after an episode of strangles.

Purulent cellulitis -
(inflammation of the subcutaneous tissue), which is an unusual occurrence where infection spreads locally in the subcutaneous tissue to the head.

Laryngeal hemiplegia -
involves paralysis of the throat muscles. It is commonly referred to as roaring. The condition may follow abscessation of cervical lymph nodes. (see pic at right).

Anaemia -
(low red blood cell count), during the convalescent period because of immune-mediated lysis of red blood cells.

Guttural pouch empyaema -
(filled with pus), which may be concurrent with classic strangles, or follow in the immediate convalescent period. The twio guttural pouches are large mucous sacs; each is a ventral diverticulum of the Eustachian tube. They are present only in Equidae and are situated between the base of the cranium dorsally and the pharynx ventrally. They open into the nasal pharynx and each has a capacity of about 300 mL.

Persistent infection in the guttural pouch may lead to inspissation (drying) of pus and, in some cases, the formation of a solid, stone-like, concretion called a chondroid. Animals that have persistent infection of the guttural pouches become the carriers, the major source of infection to spark outbreaks in susceptible horses with which they mix.

Apart from the problem of long-term guttural pouch carriers, recovered horses may shed Strep equi from their nose and in their saliva for up to 6 weeks following infection. Therefore, all horses that have had strangles should be isolated from susceptible animals for 6 weeks following infection.