Equine influenza and other respiratory viruses (e.g., rhinopneumonitis, rhinovirus) as well as bacterial infections can affect horses at any time of year. Horses that live in large barns, travel or attend events with other horses are at greater risk for these infections. Many horses that contract a viral or bacterial infection will not display overt clinical signs, but these horses can be carriers and can then infect immunocompromised horses.1 

Viral respiratory infections such as equine herpesvirus infection, equine influenza and equine viral arteritis are very common in horses. Clinical manifestations of these infections are similar and can include:

• Pyrexia

• Nasal discharge

• Submandibular lymphadenopathy

• Anorexia

• Cough

Secondary bacterial respiratory infections are often initiated by viral disease,2 since viral respiratory infections can impair respiratory defense mechanisms. In horses, the most common organisms associated with pneumonia are opportunistic bacteria originating from the resident microflora of the upper respiratory tract.1 Secondary bacterial disease may result in mucosal bacterial infections (e.g., rhinitis, tracheitis). Streptococcus equi zooepidemicus is the most common opportunistic pathogen of the equine lung, although Actinobacillus equuli, Bordetella bronchiseptica, Escherichia coli, Pasteurella spp, and Pseudomonas aeruginosa are also frequently isolated.2S. equi equi, the causative agent of strangles is a primary bacterial pathogen of the upper respiratory tract and is capable of mucosal invasion without existing disease. Rhodococcus equi is a primary pathogen of the lower respiratory tract of foals and has been reported in adult horses with a compromised immune system.

Noninfectious respiratory conditions are common, performance-limiting occurrences that affect horses. Inflammatory airway disease is characterized by excessive tracheal mucus, airway hyperreactivity, and poor exercise performance. It is thought that viral respiratory infection (EHV-2), allergies and environmental factors may play a role in these conditions.1

Bromhexine for Horses

Bromhexine (bromhexine hydrochloride) is a mucolytic that is used in the treatment of respiratory disorders associated with excessive mucus.3 Bromhexine is a derivative of the Adhatoda vasica plant, which is used in some countries for the treatment of various respiratory conditions.4 Bromhexine has been found to enhance the secretion of various mucus components by modifying the physicochemical characteristics of mucus. These changes, in turn, increase mucociliary clearance and reduce cough.

Bromhexine supports the body's natural mechanisms for clearing mucus from the respiratory tract. It is secretolytic, increasing the production of serous mucus in the respiratory tract, which makes the phlegm thinner and less viscous.3,4 This allows the cilia in the respiratory tract to more easily transport phlegm out of the lungs.

Where to buy Bromhexine 

Bromhexine is available in the U.S. through pharmaceutical manufacturers and through veterinary custom compounding companies. BROMHEXINE 18 MG/ML, ORAL SUSPENSION 500ML by NexGen Pharmaceuticals is indicated for the treatment of cough in horses resulting from both infections and noninfectious causes.

Please consult your veterinarian prior to beginning any treatment regimen.

FOR RX ONLY: A valid prescription from a licensed veterinarian is required for dispensing this medication.

1aaep.org.

2Merck Veterinary Manual.

3Pearce, H.G.; Wyburn, R.S.; Goulden, B.E. (1979) Clinical use of Bisolvon (bromhexine) in some respiratory diseases of the horse. New Zealand Veterinary Journal (1978) 26 (1/2) pp. 28-30.

4Zanasi, A., Mazzolini, M. & Kantar, A. A reappraisal of the mucoactive activity and clinical efficacy of bromhexine. Multidiscip Respir Med 12, 7 (2017).