Risk factors, prognostic indicators, and outcome of pyothorax in cats: 80 cases (1986-1999)

J Am Vet Med Assoc. 2002 Sep 15;221(6):819-24. doi: 10.2460/javma.2002.221.819.


Objective: To identify risk factors associated with development of pyothorax in cats, assess survival rates for cats that are treated, determine prognostic indicators, and determine recurrence rates.

Design: Retrospective study.

Animals: 80 cats with pyothorax and 212 control cats.

Procedure: History; month of evaluation; physical examination findings; results of hematologic, serum biochemical, and retrovirus testing; radiographic findings; outcome; recurrence rate; and necropsy findings were recorded. For control cats, age, sex, breed, indoor versus outdoor status, vaccination history, and single- versus multi-cat household status were recorded.

Results: Cats from multi-cat households were 3.8 times as likely (95% confidence interval, 1.9 to 8.2) to develop pyothorax, compared with cats from single-cat households. Indoor or outdoor status was not a risk factor. Cats with pyothorax were significantly younger (mean, 3.83 +/- 3.43 years) than controls (mean, 5.62 +/- 5.27 years). Nonsurvivors had significantly lower heart rates than survivors. Hypersalivation was significantly more common in nonsurvivors (11/39; 26.8%) than survivors (1/39; 3%). Overall, 48.8% (39/80) of cats survived. When cats that were euthanatized without treatment were excluded from analyses, the survival rate was 66.1% (39/59). Pyothorax recurred in 1 of 17 cats for which follow-up information was obtained.

Conclusions and clinical relevance: Cats with pyothorax that received treatment had a fair to good prognosis, with low recurrence rates in survivors. Hypersalivation and low heart rate were associated with worse clinical outcome. Cats with pyothorax were likely to come from multi-cat households.

MeSH terms

  • Age Factors
  • Animals
  • Anti-Bacterial Agents / therapeutic use*
  • Cat Diseases / microbiology
  • Cat Diseases / mortality
  • Cat Diseases / therapy*
  • Cats
  • Drainage / veterinary
  • Empyema, Pleural / microbiology
  • Empyema, Pleural / mortality
  • Empyema, Pleural / therapy
  • Empyema, Pleural / veterinary*
  • Female
  • Heart Rate
  • Male
  • Prognosis
  • Recurrence
  • Retrospective Studies
  • Risk Factors
  • Sialorrhea / complications
  • Sialorrhea / veterinary
  • Survival Analysis
  • Treatment Outcome


  • Anti-Bacterial Agents