The first topic covered during the Respiratory Diseases Table Topic at the 2011 American Association of Equine Practitioners annual convention, held Nov. 18-22 in San Antonio, Texas, was management of horses with pleuropneumonia, which is an infection of the lungs and pleural space (area around the lungs). In a majority of the cases there is an accumulation of fluid in the pleural space. Veterinarians diagnose this conditions using ultrasound, and findings include an accumulation of fluid in the pleural space and evidence of consolidation or abscessation of the lungs. The initial approach to managing these cases entails aggressive antimicrobial treatment in addition to supportive care. The most common antibiotic choice is a broad-spectrum antibiotic(s) (coverage for both Gram positive and Gram negative bacteria). This would include antibiotics such as the combination of penicillin and gentamicin or chloramphenicol. Most veterinarians also treat with metronidazole in case an anaerobic bacterium is present. Once bacterial culture results are available, treatment is usually modified.

Veterinarians often perform thoracocentesis, which a procedure to remove excessive fluid from the pleural space. It is best to perform this procedure when a large volume of pleural fluid is present or when the horse is having respiratory difficulties due to the fluid accumulation. Sometimes the excessive fluid will return and the procedure will have to be repeated or tubes will be left in place to allow for constant drainage. Occasionally cases will benefit from lavage of the pleural space with saline or saline with antibiotics or anti-inflammatory agents. The prognosis for horses with pleuropneumonia is fair to good and, as with any disease, the more complications the worse the prognosis. Possible complications include laminitis, thrombophlebitis (blood vessel wall inflammation), diarrhea, infection at the site of thoracocentesis, and endotoxemia.

Veterinarians in attendance also discussed equine multinodular pulmonary fibrosis (EMPF). This disease is a type of interstitial pneumonia that has been associated with equine herpesvirus 5. The horse can present with fever, cough, nasal discharge, or respiratory distress. Often the horse is treated for bacterial pneumonia but does not appear to improve. Ultrasound and radiographs will reveal nodular lesions. Treatment includes antibiotics (for pneumonia) and anti-inflammatory agents such as banamine or corticosteroids. Veterinarians might also administer antiviral medications, such as acyclovir or valacyclovir. The prognosis for a majority of the cases is poor.

The final table topic discussion was on management and treatment of horses with lower airway inflammation, which can manifest as inflammatory airway disease (IAD) or heaves/restrictive airway disease (or COPD). Horses with inflammatory airway disease present with exercise intolerance, poor performance or coughing when worked; whereas horses with restrictive airway disease present with an increased respiratory effort. Management of each case is different but the most important factor is maintaining the horse in an appropriate environment including avoiding dusty bedding (straw), maximizing turnout, stalling horses away from bedding/hay, minimizing activities that create dust (sweeping or blowing the aisle), and soaking hay (or limiting amount of hay) to reduce possible allergen load. Additional treatments include inhalation therapy and systemic corticosteroids. With appropriate management these cases can resume an athletic career.

This Table Topic was moderated by Bonnie Barr, VMD, Dipl. ACVIM, of Rood & Riddle Equine Hospital in Lexington, Ky., and Keith Chaffin, DVM, MS, Dipl. ACVIM, a professor of medicine at Texas A&M University's School of Veterinary Medicine in College Station.

About the Author

Bonnie Barr, VMD, Dipl. ACVIM

Bonnie Bar, VMD, Dipl. ACVIM, is a shareholder at Rood & Riddle Equine Hospital, in Lexington, Kentucky.

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