Pleuropneumonia can require intensive and expensive treatment. Once it develops–and the horse is accumulating fluids between his lungs and his chest wall–the fluids will need to be drained via tubes inserted through the rib cage. This procedure is likely to be repeated multiple times over the course of the illness.
And it may difficult to drain the fluid. “The inflamed pleural membrane forms fibrin, a type of stringy tissue that can trap bacteria and also make it hard to remove the fluid in the chest,” says Virginia Buechner-Maxwell, DVM, DACVIM, of the Virginia– Maryland Regional College of Veterinary Medicine in Blacksburg, Virginia. “It becomes a cobweb of fibrous material between the lung and chest wall, like a honeycomb of tissue. This is a very serious condition.”
In these cases, the veterinarian may suggest a thoracoscopy: “We put a scope into the pleural cavity the same way that a laparoscopy is done into the abdomen. The scope goes into the chest cavity, in between the ribs,” says Amy Johnson, DVM, DACVIM, of the University of Pennsylvania. “With the scope we can possibly see what we are doing as we try to drain the pleural cavity.”
The thoracoscopy may also be used to drain fluid from another potential complication: abscesses. “As time goes on the horse may develop necrotizing pneumonia, in which parts of the lung tissue die, or he may develop abscesses within the pleural cavity or within the lung,” Johnson says. “Since those abscesses become walled off very quickly, they can be really hard to treat. Once the infection is walled off, it’s harder for antibiotics to penetrate into the infected area.”
In this situation, the horse may need to continue with antibiotic treatment for many months, or if the area is surgically accessible the veterinarian may do surgical procedures to either drain the abscess or reduce its size. Some abscesses that are mainly fluid can also be drained without surgery. “We can put a tube into the abscess and drain most of the pus out of the middle of it,” Johnson says.
The most severe cases might require a thoracotomy, a surgical incision through the chest wall. “Sometimes the surgeon will reach a hand in through the ribs to try to scoop out as much of the purulent debris as possible,” Johnson says. “In some cases, in order to access the infected area, the surgeon has to do a rib resection, which involves removing part of a rib. This allows the surgeon to get to the site and drain an abscess or an infected area within the chest cavity.”
Even with treatment this extensive, the prognosis can be good. “We are able to save a lot of these horses, even if they do need rib resections or surgical procedures to drain abscesses. We aren’t able to save all of them, but the horse has a fair chance of survival,” says Johnson. “The cost, however, can be high—tens of thousands—
MANAGEMENT: When a horse develops pleuropneumonia, the fluids that accumulate between his lungs and the chest wall must be drained.
by the time you pay for the months of antibiotics required, the repeated chest tubes and drainage, and the surgical procedure. Most owners don’t have the ability to pursue this extensive treatment.”
But, Johnson adds, “Most cases, if detected relatively early, can be managed just with antibiotics, plus or minus chest tubes, without doing the more invasive thoracoscopy or a thoracotomy and rib resection.”