Pulmonary Congestion and Edema
Engorgement of the pulmonary vascular bed and subsequent increase in the amount of blood in the lung parenchyma is called pulmonary congestion, which later on leads to the escape of fluid into the interstitial space and alveoli, referred as pulmonary edema.
- Primary congestion is due to inhalation of toxic fumes and smoke, anaphylactic shock, hypostatic congestion of lungs (prolonged recumbency due to downer cow syndrome, milk fever, fracture of long bone).
- Secondary congestion occurs due to CHF.
Pulmonary edema can occur due to acute anaphylaxis,pneumonic pasteurellosis, gram negative sepsis in pigs, CHF, inhalation of toxic gases and fumes, the pulmonary form of African horse sickness, and baker’s syndrome in foals.
Pathogenesis
Reduced effective alveolar space,reduced vital capacity of the lungs, and impaired oxygenation of the blood are the hallmarks of pulmonary congestion and edema; the end effect is anoxic hypoxia.
Clinical Signs
Increased depth of respiration to the point of extreme dyspnea, open-mouth breathing, a typical stance with front legs spread wide apart and abducted elbows, and the presence of crackles on auscultation over the lower parts of the lungs are characteristics of this respiratory disease.
Diagnosis
- The diagnosis of pulmonary congestion and edema can be made based on clinical findings.
- lab investigation suggestive of bacterial isolation from nasal swabs, eosinophilia on a haematological examination.
Treatment
- Epinephrine in anaphylactic shock
- Antihistamines like chlorpheniramine maleate and promethazine
- Diuretics like frusemide at 1-2 mg/kg body weight IM.
- Acetylsalicylic acid is more effective than antihistamines in providing symptomatic relief.
- Corticosteroids like hydrocortisone at 1 mg/kg body weight have beneficial effects as anti-inflammatory agents.
