Editor's note: This article is part of TheHorse.com's ongoing coverage of topics presented at the 2012 American College of Veterinary Internal Medicine Forum, held May 30 - June 2 in New Orleans, La.
There are several methods by which to treat equine pleuropneumonia (pleuritits) and associated pleural abscesses, but when all else fails surgical options might be required. At a recent veterinary conference, one researcher discussed a procedure called thoracotomy (an incision into the pleural space of the chest) for treating recurrent pleural abscesses.
At the 2012 American College of Veterinary Internal Medicine Forum, held May 30-June 2 in New Orleans, La., Keith Chaffin, DVM, MS, Dipl. ACVIM, a professor of equine internal medicine at the Texas A&M University College of Veterinary Medicine, discussed indications for thoracotomies and the outcomes of several thoracotomy procedures.
Background: Pleuropneumonia and Pleural Abscesses
Pleuropneumonia--inflammation both within the lung and within the pleural cavity--is a relatively common disorder in horses that often results in thoracic abscesses, Chaffin explained. Pleuropneumonia risk factors include:
- Long-distance transportation;
- Intense exercise;
- Viral infections;
- Upper airway dysfunction;
- Recent general anesthesia;
- Choke; and
- Aspiration.
Chaffin said clinical signs of disease development include:
- Fever;
- Lethargy;
- Anorexia;
- Cough;
- Increased heart and/or respiratory rate;
- Nasal discharge;
- Exercise intolerance;
- Bad breath;
- Sternal edema (fluid swelling on the chest area);
- Pleurodynia (pain in the chest lining); and
- Weight loss.
Pleuropneumonia treatment, Chaffin said, depends on a number of factors associated with the disease. Commonly employed treatment modalities include:
- Antimicrobial and/or anti-inflammatory drug administration;
- Pleural drainage;
- Pleural lavage;
- Intra-pleural antimicrobial agents;
- Rest;
- Intravenous fluids; and
- Supportive care.
In the event horses fail to respond to these less invasive options, surgical intervention becomes plausible, he said.
Surgical Intervention
"In horses with recurrent pleural abscesses (resulting from pleuropneumonia) that are refractory to medical therapy, surgical intervention is needed to facilitate manual debridement and lavage of the abscess cavity," Chaffin said. In these cases, veterinarians typically perform a thoracotomy, he said.
"In my experience, proper case selection is critical for a successful outcome," Chaffin said. A good candidate for a thoracotomy, he said, is one that doesn't respond to medical treatment and has "significant amounts of dead lung material and pus within a compartment of the pleural space." Horses should also be in a stable systemic condition prior to undergoing surgery.
During a thoracotomy the veterinarian makes a surgical incision into the thoracic wall to gain access to affected areas of the body. Chaffin said there are several different approaches to performing a thoracotomy, and the attending surgeon or veterinarian will select the appropriate procedure for each individual patient.
He explained that one common procedure is called a standing intercostal myectomy, where an incision is made between the ribs. The other common procedure, he said, is a partial rib resection, where a portion of a rib is removed to allow improved access to the thoracic abscess. Regardless of the procedure selected, the goal is to evacuate adverse material from the abscess and to provide adequate lavage (flushing) to promote complete healing of the abscess, he explained.
Several studies have evaluated the outcome of thoracotomies, Chaffin said. "In previous reports of small numbers of cases, clinical improvement has been reported in most cases," he said. Each case's prognosis depends on disease severity and the adequacy of the procedure for accomplishing the goals.
Another study evaluated outcomes of 16 horses that underwent thoracotomy. Fourteen survived to discharge from the hospital, and 46% of the survivors returned to their previous level of work.
Chaffin said that potential complications include pneumothorax (air in the chest cavity), cellulitis, draining tracts, and recurrence of the thoracic abscess. In most cases, the healing time is two to three months.
Take-Home Message
While many horses recover from pleuropneumonia with medical therapy alone, others will require a thoracotomy to provide complete healing. Understanding the indications for thoracotomy, the different surgical techniques, potential complications, and prognosis can help ease the decision making process if your veterinarian recommends surgery for your horse.
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.