Equine asthma is likely the most common cause of nasal discharge and cough in horses that are otherwise well. Diagnosis can be made with bronchoalveolar lavage. Antimicrobial therapy is not indicated.
Viral Respiratory Infections
These appear common in young horses, especially those in large groups. Horses can have nasal discharge ranging from mucoid to purulent, with or without a cough, but are otherwise well. Physical examination should be performed. Animals are afebrile and lung auscultation is unremarkable. Antimicrobial therapy is not indicated. Most recover without antimicrobial therapy in 7-10 days.
The strangles guidelines are based on the ACVIM consensus statement on Streptococcus equi Infection in Horses
|Stage of disease||Antimicrobial therapy|
Early clinical signs
– No abscessation
Antimicrobials may be curative and prevent focal abscessation however treated animals are likely to remain susceptible to reinfection.
Penicillin G 3-5 days
|Lymph node abscessation||Antimicrobials contraindicated unless dyspnoea is present due to upper airway obstruction. If abscesses have burst no antimicrobials required.|
|Complications – Metastatic spread||Long term penicillin therapy and abscess drainage if possible|
|Complications – Carriers of infection in guttural pouches||
Repeated lavage and removal of chondroids endoscopically
Topical benzylpenicillin as gel (see below)
Systemic penicillin G (IM or IV)
To make benzylpenicillin gel:
Weigh 2g gelatin and add to 40ml sterile water. Microwave or heat to dissolve gelatin. Cool to 45-50°C.
Add 10ml sterile water to 10,000,000 units sodium benzyl penicillin G. Mix penicillin solution with cooled gelatin.
Place in syringes and refrigerate overnight to set.
A sample of fluid from the sinus should be obtained to confirm the diagnosis. Culture is not usually required.
Consider underlying disease (dental or equine Cushing’s) especially if recurs.
Sinus lavage alone may be sufficient and is almost always required for successful outcome (minimally invasive technique in the field can be used).
Systemic antimicrobials when:
- Recurrent disease
- Systemically unwell
In these cases, penicillin or trimethoprim / sulphonamide is first line therapy.
Transtracheal wash, or endoscopic tracheal wash with a triple guarded catheter, should be performed for cytological evaluation. Culture and susceptibility testing should be performed in all cases. Culture of bronchoalveolar lavage specimens is never appropriate as these samples are contaminated by the upper airway.
Should be based on culture and susceptibility results. Empirical therapy with penicillin & gentamicin should be initiated pending results. Metronidazole should be added if anaerobes are suspected (foul smell to tracheal fluid).