Pleural Effusion in Dogs and Cats
World Small Animal Veterinary Association World Congress Proceedings, 2005
Helio Autran de Morais, DVM, PhD, ACVIM
Internal Medicine and Cardiology, University of Wisconsin, Madison

Pleural effusion is a common cause of dyspnea in dogs and cats. It is classically an expiratory or mixed dyspnea with absence of normal lung sounds ventrally. In some animals a "fluid line" can be detected, where lung sounds are absent ventral to an imaginary horizontal line and increased dorsal to the line. Clinical sings are more severe with larger volumes of fluids and when fluid accumulates acutely. Clinical approach is based on chest radiographs and thoracocentesis. Radiographs confirm the presence of fluid and subjectively access the amount, as well as potential causes (e.g., heart failure, neoplasia), whereas thoracocentesis provides a sample for analysis. Severely dyspneic patients should be taped before radiographs are obtained. Removal of even small amounts of fluid may substantially decrease the animal's ventilatory effort. Fluid inside the pleural cavity can be classified as transudate (protein < 2.5 g/dl, cells < 1,500/µl), modified transudate (protein: 2.5-4.0 g/dl, cells 1,000-7,000/µl, mostly mesothelial cells and macrophages), exudates (protein > 3 g/dl, cells > 7,000/µl, mostly degenerate neutrophils), chyle (protein variable, cells < 10,000/µl, mostly lymphocytes) or blood (protein, cells and PCV similar to peripheral blood). Cats with FIP can have a fluid with elevated protein (> 5 g/dl), but not very cellular (< 10,000/µl).

Pure transudate is more likely caused by hypoalbuminemia, but it may also occur in patients with bilateral heart failure or neoplastic effusions, although the latter two are usually present a modified transudate. A modified transudate can also occur in patients with effusions secondary to vasculitis, diaphragmatic hernia and lung lobe torsion. Exudate is found in patients with pyothorax, cats with FIP or in some cases of vasculitis. Multiple organisms are often cultured in patients with bacterial pyothorax. In cats, obligate anaerobes or Pasteurella spp. are most common, whereas in dogs obligate anaerobes or Actinomyces and Nocardia spp are frequently cultured. Chylothorax is observed when there is interference with lymphatic drainage or from increased lymphatic flow. Heart failure should be considered as a differential in patients with chylothorax, particularly in cats.

Therapy of pleural effusion consists of maintaining the chest free of fluids and addressing the underlying disease. Some patients may require placement of a chest tube. Antibiotics and pleural lavage are necessary in patients with pyothorax. Surgery may be needed if there is a foreign body or a lung abscess. Chylothorax can be managed medically by feeding a low-fat diet, performing needle thoracentesis as needed, and using a benzopyrene such as Rutin. Surgery is indicated in patients that do not respond to medical therapy.

Speaker Information
(click the speaker's name to view other papers and abstracts submitted by this speaker)

Helio Autran de Morais, DVM, PhD, ACVIM
Brazil


MAIN : Respiratory Disease : Pleural Effusion
Powered By VIN

Friendly Reminder to Our Colleagues: Use of VIN content is limited to personal reference by VIN members. No portion of any VIN content may be copied or distributed without the expressed written permission of VIN.

Clinicians are reminded that you are ultimately responsible for the care of your patients. Any content that concerns treatment of your cases should be deemed recommendations by colleagues for you to consider in your case management decisions. Dosages should be confirmed prior to dispensing medications unfamiliar to you. To better understand the origins and logic behind these policies, and to discuss them with your colleagues, click here.

Images posted by VIN community members and displayed via VIN should not be considered of diagnostic quality and the ultimate interpretation of the images lies with the attending clinician. Suggestions, discussions and interpretation related to posted images are only that -- suggestions and recommendations which may be based upon less than diagnostic quality information.

CONTACT US

777 W. Covell Blvd., Davis, CA 95616

vingram@vin.com

PHONE

  • Toll Free: 800-700-4636
  • From UK: 01-45-222-6154
  • From anywhere: (1)-530-756-4881
  • From Australia: 02-6145-2357
SAID=27