Fibrinous Pleural Effusion in Horses with Pleuropneumonia

Fibrinous Pleural Effusion in Horses with Pleuropneumonia

Researchers identified several significant associations between fibrinous pleural effusion and a poor prognosis.

Photo: Erica Larson, News Editor

Fibrous pleural effusion is a common and often detrimental development associated with pleuropneumonia—pneumonia complicated by the development of pleurisy (inflammation of the thin, transparent membrane covering the lungs and lining the chest cavity). In horses with fibrinous pleural effusion, fibrin—a sticky protein—accumulates in the already fluid-filled area around the lungs, hindering the healing process.

“A big part of treating pleuropneumonia is to remove the fluid, which removes a lot of pro-inflammatory proteins and bacteria in addition to relieving the pressure collapsing the lungs,” explained lead researcher Joy Tomlinson, DVM, Dipl. ACVIM, now a clinical fellow at the Cornell University College of Veterinary Medicine, in Ithaca, New York. “If there is a lot of fibrin in the fluid, it can create many pockets, which prevent (veterinarians from) draining all the fluid through one tube. The fibrin can also prevent antibiotics from moving through the fluid and killing the bacteria.”

In humans, researchers have determined that fibrinous pleural effusion is associated with decreased efficacy of pleural fluid drainage and increased risk of medical treatment failure, but similar associations have not been established in horses, the researchers said.

So, Tomlinson and colleagues at the University of Pennsylvania School of Veterinary Medicine’s New Bolton Center, in Kennett Square, set out to take a closer look at fibrinous pleural effusion in horses and its association with an increased risk of complications and/or death.

In their retrospective study, the team analyzed 10 years’ worth of data from 74 horses diagnosed with lung disease and treated at the university’s veterinary medical center. The researchers determined that 63 horses were considered fibrinous either at or after admission to the clinic. They also identified several significant associations between fibrinous pleural effusion and a poor prognosis:

  • Of the 63 fibrinous horses, 42 developed further complications such as pleural abscess, laminitis, or colic during hospitalization;
  • None of the nonfibrinous horses required surgical intervention (a thoracotomy, which is an incision into pleural space to remove diseased lung or drain pleural abscess); and
  • All nonfibrinous horses survived to discharge, while only 69% of fibrinous horses survived. The team noted that some of the fibrinous horses were euthanized due to a poor prognosis.

Since most horses with pleuropnemonia do develop fibrinous pleural effusion, the team recommends that veterinarians pursue fibrinolytic treatment to improve survival rates for affected horses. This is a novel treatment using a medication “that breaks up fibrin directly in the pleural space where it can immediately act on fibrin present there,” said Tomlinson.

The study, “The Association of Fibrinous Pleural Effusion with Survival and Complications in Horses with Pleuropneumonia,” was published in the Journal of Internal Veterinary Medicine

About the Author

Casie Bazay, NBCAAM

Casie Bazay holds a bachelor of science degree in education from Oklahoma State University. She taught middle school for ten years, but now is a nationally certified equine acupressure practitioner and freelance writer. She has owned Quarter Horses nearly her entire life and has participated in a variety of horse events including Western and English pleasure, trail riding, and speed events. She was a competitive barrel racer for many years and hopes to pursue the sport again soon.

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