Endoscopy Brief: Identifying the cause of acute cough and respiratory distress in a toy poodle - Veterinary Medicine
  • SEARCH:
Medicine Center
DVM Veterinary Medicine Featuring Information from:

ADVERTISEMENT

Endoscopy Brief: Identifying the cause of acute cough and respiratory distress in a toy poodle

The final diagnosis was bacterial pneumonia and lung lobe consolidation caused by E. cloacae. The relationship between the lobar pneumonia and the bronchial collapse is unclear. The pneumonia may have been secondary to primary bronchial collapse and a resulting decrease in mucocilliary clearance; however, primary lower airway disease can cause secondary lower airway collapse due to alterations in intrathoracic pressures. Chronic bronchitis can predispose a patient to both pneumonia and lower airway collapse, but this dog's history and radiographic evidence did not support this scenario. Because the patient was lost to follow-up, the cause of the bronchial collapse could not be pursued.

DISCUSSION

Differential diagnoses in dogs with coughing and respiratory difficulty are many. Some of the more common differential diagnoses in older, small-breed dogs include cardiogenic causes (e.g. mitral insufficiency with left atrial enlargement and pressure on the left mainstem bronchus, cardiogenic pulmonary edema, heartworms) and airway or parenchymal causes (e.g. collapsing trachea, infectious tracheobronchitis, chronic bronchitis, neoplasia, pneumonia, pulmonary thrombosis).

Dogs with bronchopneumonia often present with signs of lower respiratory disease such as coughing (more common in dogs than cats), exercise intolerance, respiratory distress, and nasal discharge. However, the only identifiable clinical signs may be subtle—depression, weight loss, and decreased appetite may be all that are present. Increased lung sounds may be heard over the affected lung fields (dependent lung fields are usually more severely affected). Fever may or may not be present.1

A complete blood count may show a stress leukogram or a neutrophilic leukocytosis with or without a left shift. The classic inflammatory leukogram may not be present.1 Thoracic radiographs may show an interstitial pattern early in the disease process or an alveolar pattern as the disease progresses. Diagnostic confirmation of bacterial pneumonia is based on results of bacterial culture and antimicrobial sensitivity testing of lower airway and alveolar secretions obtained by tracheal wash or bronchoalveolar lavage. Common pathogens isolated from the lower respiratory tract include Escherichia coli, Pasteurella species, Klebsiella pneumoniae, Bordetella bronchiseptica, Pseudomonas aeruginosa, and Staphylococcus and Streptococcus species.2 Species belonging to the Enterobacteriaceae family have also been commonly reported.3 Anaerobic cultures should also be performed, and Mycoplasma species cultures should be considered, especially in young dogs and cats.1

In cases of bacterial pneumonia, a predisposing abnormality often exists. Examples of such abnormalities include decreased clearance of inhaled debris from the airways, such as that which occurs in patients with chronic bronchitis, tracheal or bronchial collapse, bronchiectasis, or ciliary dyskinesia. Immunosuppression (caused by drugs, malnutrition, stress, endocrinopathies, viral infections), aspiration, inhaled foreign bodies, neoplasia, fungal disease, and pulmonary parasites can also predispose an animal to bacterial pneumonia.2 Indwelling intravenous, arterial, and urinary catheters can increase the risk of bacterial pneumonia.1 Most cases of bacterial pneumonia result from bacterial entry through the airways.1 This route of infection most commonly affects the dependent airways, assuming a cranioventral pattern.1 Bacterial pneumonia of a hematogenous origin often presents as a caudal or diffuse pattern with increased interstitial involvement.1

The treatment of bacterial pneumonia consists primarily of supportive care and appropriate antibiotic therapy. Significantly more patients respond to antibiotics based on results of bacterial culture and antimicrobial sensitivity testing than on empirical therapy.4 Reasonable initial antibiotic choices pending the results of sensitivity testing include cephalexin, trimethoprim-sulfadiazine, chloramphenicol, or amoxicillin trihydrate-clavulanate potassium. If the infection is life-threatening, as with concurrent sepsis, intravenous treatment with broad-spectrum antibiotics is indicated. Aerosol administration of antibiotics by nebulization can be used in addition to systemic therapy.1

Use intravenous fluids to maintain adequate hydration of the airways and to facilitate mucociliary clearance. It is important to note that diuretics counteract airway hydration, so they should not be used. Airway humidification with a nebulizer or vaporizer for 15 to 20 minutes, three to four times a day, also aids mucociliary clearance, as does frequent coupage. Supplemental oxygen may be needed in patients with low oxygen partial pressure.5 The use of bronchodilators is controversial, and corticosteroids and cough suppressants should be avoided.1


ADVERTISEMENT

Source: VETERINARY MEDICINE,
Click here