Respiratory Disease: When Antibiotics Aren't Needed
I'm trying not to sound like a broken record when it comes to antibiotics, but it's a very important topic so you'll see many posts on the subject. When you consider that antibiotic-associated diarrhea is a potentially life-threatening problem in horses, and that antibiotic-resistant bacteria are becoming more common in general, it should be obvious that we need to limit the use antibiotics to when they are actually needed, and potentially effective. Horses with respiratory disease are commonly treated with antibiotics. However, as discussed in a previous post ("Snotty-Nosed Horses: What To Do?"), there are many causes of respiratory disease in horses, and most of them are not bacterial.
A common cause of nasal discharge and coughing in horses is inflammatory airway disease (IAD, which is somewhat similar to asthma in people). This condition is different from heaves, which typically occurs in older horses and causes more severe clinical signs. However, horses with IAD may cough and/or have clear nasal discharge. They may also have decreased athletic performance. They do no have a fever, decreased appetite or other signs associated with an infection. However, antibiotics are (unfortunately) commonly used to "treat" these horses, which makes very little sense. A few years ago a study was done looking at antibiotic treatment history (i.e. prior to diagnosis) in 55 horses diagnosed with non-septic inflammatory airway disease at the Ontario Veterinary College. Here are the highlights:
- 69% of horses were given an antibiotic for treatment of their respiratory disease. 52% received more than one antibiotic, and 19% received 3 different antibiotics.
- Horses were treated with antibiotics for extended periods of time, with an average of 9.9 days.
- No testing was performed to detect bacterial infection in any horse prior to treatment.
- 21% of the horses that received antibiotics did not have any abnormal clinical signs beyond poor performance - not even nasal discharge.
- Horses with a history of coughing were more likely to have received an antibiotic, but cough is a very non-specific clinical sign that does not necessarily indicate an infection, let alone a bacterial infection.
Antibiotics are important drugs, but we overuse them (in people and in animals). We need to be careful with when and how we use to ensure they have the maximum beneficial effect and to reduce the risks of side effects or increasing bacterial resistance.
More information on inflammatory airway disease is available in the consensus statement on IAD in horses from the American College of Veterinary Internal Medicine (ACVIM).
