Bacterial Bronchopneumonia in Dogs

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Bronchopneumonia is an inflammation of the lungs and the bronchi, which are the larger air passages conveying air to and within the lungs. Bronchopneumonia is usually related to a bacterial infection and may be caused by many different kinds.

Bacterial pneumonia is an important cause of illness and death in dogs, especially in hospitalized animals. The route of infection is typically inhalation, and bacteria that is spread by blood is less common and can be very difficult to treat.

Pneumonia can occur in dogs and cats, but is more common in dogs. Sporting dogs, hounds, working dogs and mixed breed dogs over 25 pounds may be predisposed. Most affected pets are under one year of age. However, the age range varies from two months to 15 years.

Prompt recognition and treatment of bronchopneumonia is important.

What to Watch For

  • Rapid breathing (tachypnea)
  • Respiratory distress
  • Productive cough
  • Fever
  • Depression
  • Mucopurulent nasal exudates (fluids)
  • Anorexia
  • Listlessness

    Diagnosis

    Diagnostic tests are needed to recognize bronchopneumonia and exclude other diseases. Your veterinarian should perform a complete medical history and physical examination, including careful auscultation of the heart and lungs. Lung sounds are often abnormal with a "crackle" upon auscultation when your dog takes a deep breath.

    Medical history may include questions regarding your pet's previous illness or illnesses, therapy and response to therapy, appetite, weight loss, activity or exercise intolerance, cough and environmental exposure to dusts, smoke and vapors. Other tests may include:

  • Chest X-rays
  • Complete blood count (CBC)
  • Airway cytology
  • Culture (tracheal wash cytology and culture and sensitivity)

    Other tests may include:

  • Heartworm test
  • Bronchoscopy

    • Bronchopneumonia in dogs is usually related to a bacterial infection.

    • Bronchoscopy is a procedure consisting of placing a small flexible fiberoptic tube into the airway. Dogs are under anesthesia for this procedure.

    Treatment

    Pneumonia causes difficulty breathing and can be a severe and progressive condition. Severely ill pets may require hospitalization with oxygen, intravenous fluids, antibiotics and supportive care. Mildly affected pets that are well hydrated and eating properly may be treated as outpatients, but would require frequent follow-ups to monitor the progression of the infection. Treatments for bronchopneumonia may include one or more of the following:

  • Antibiotics for at least three weeks or longer pending clinical results and radiographs

  • Humidified oxygen for animals that have trouble breathing

  • Plenty of fluids and warmth

  • Airway humidification to assist in expectoration of secretions

  • Percussion of the thorax (coupage) to help loosen and remove secretions

    Some treatment may not be of help and are rarely used. These include:

  • Expectorants like guaifenesin

  • Bronchodilator therapy, although it may reverse irritative bronchoconstriction and strengthen respiratory muscle effort in dyspneic animals.

  • Cough suppressants

    Home Care and Prevention

    Keep your pet warm, dry and indoors, if possible, and encourage him to eat and drink. Avoid cough suppressants.

    Follow-up with your veterinarian for examinations, laboratory tests and radiographs. Administer any veterinary-prescribed antibiotics.

    Do not over-exercise your pet; allow only what your pet can tolerate. Do not allow your pet to get short of breath during exercise/activity. Use a harness instead of a collar; this is less restricting to the neck, and will allow your pet to breathe easier.

    There aren't any specific recommendations for prevention of pneumonia other than eliminating the predisposing causes. If your pet is exposed to smoke, dusts, fumes, barns or crop dust, these should be eliminated. Provide routine vaccinations as recommended by your veterinarian and vaccinate dogs for kennel cough (Bordetella bronchiseptica) if boarding or if there is much exposure to other dogs.

  • It is essential to consider the underlying risk factors and predispositions for pneumonia. This can help eliminate the cause and prevent its reoccurrence. Underlying risk factors may include:

  • Contagious upper respiratory infection

  • Pre-existent lung disease (bronchitis, lungworms, systemic mycoses, lung contusion, heartworm disease, smoke inhalation, thromboembolic disease)

  • A collapsed or airless state of the lung (pulmonary atelectasis)

  • Vomiting or difficulty swallowing associated with inhalation aspiration (inhalation) of pharyngeal or gastric fluid or contents

  • Oro-nasal sources of infection (sinusitis, dental disease)

  • Immunosuppression caused by a virus or disease

  • Immunosuppressive drug therapy (glucocorticoids, chemotherapy)

  • Abnormal respiratory defense mechanisms (Cushing's disease, chronic bronchitis, ciliary dyskinesia, neutrophil dysfunction syndromes)

  • Bronchial foreign body

  • Foreign body aspiration pneumonia from food or mineral oil, for example

  • Debilitation- and hospitalization-related infection (nosocomial)

  • Indwelling intravenous catheter sepsis (hematogenous spread)

  • Contaminated endotracheal tube, tracheostomy tube or bronchoscope

  • Aspiration (inhalation) of liquid foreign material during diagnostic or therapeutic procedures (barium sulfate, medications, mineral oil)

  • History of thoracic surgery or atelectasis

    Other medical problems can lead to symptoms similar to those encountered in bronchopneumonia. Organisms that can cause bronchopneumonia may include:

  • Viruses
  • Rickettsia
  • Bacteria
  • Mycoplasma spp.
  • Fungi
  • Protozoa
  • Nematodes/trematode

    Diseases that can appear similar to those with bronchopneumonia include:

  • Acute bronchitis
  • Aspiration (inhaling)
  • Bronchial foreign body
  • Chronic bronchitis
  • Congestive heart failure (pulmonary edema)
  • Electrical cord shock (non-cardiogenic pulmonary edema)
  • Heartworm disease
  • Infectious tracheobronchitis
  • Inflammatory lung disease (noninfectious)
  • Infection within the chest cavity (pyothorax)
  • Viral pneumonia (canine distemper virus, canine adenovirus)
  • Rickettsia pneumonia (ehrlichiosis or Rocky Mountain spotted fever)
  • Protozoal pneumonia (toxoplasmosis)
  • Parasitic pneumonia (capillariasis, paragonimiasis, aelurostrongylus, dirofilariasis)
  • Fungal pneumonia (histoplasmosis, Blastomycosis, coccidiomycosis)
  • Pulmonary abscess (pus in the lungs)
  • Pulmonary embolism (sudden artery blockage in the lungs)
  • Pulmonary fibrosis (development of fibrous tissue in the lungs)
  • Pulmonary hemorrhage (e.g. anticoagulant rodenticide)
  • Pulmonary neoplasia (cancer)
  • Respiratory parasites
  • Rhinitis (nasal inflammation due to fungus or bacteria)
  • Sinusitis/pharyngitis
  • Tonsillitis

  • Diagnosis In-depth

    Veterinary care should include diagnostic tests and subsequent treatment recommendations. Diagnostic tests are needed to recognize bronchopneumonia and exclude other diseases.

    A complete medical history and thorough physical examination should be performed by your veterinarian. Clinical signs, radiography and a hemogram are usually sufficient to make a presumptive diagnosis of bacteria pneumonia. Airway cytology and culture can confirm the diagnosis.

  • Radiography (chest x-rays) can often check for increased lung density (lung consolidation). Lung changes may differ with bacterial versus fungal, viral or parasitic infections.

  • A complete blood count (CBC) may indicate signs of infection with an elevated white blood cell count and an increased number of immature cells (increased band count). The magnitude of change is not consistently related to the extent of infection. Overwhelming bacterial pneumonia may cause a low neutrophil cell count.

  • A tracheal wash is a procedure in which a fluid sample from the trachea is analyzed. This test is also called a trans-tracheal wash (TTW). Fluid samples can be obtained by placing a small needle into the trachea in a lightly sedated patient. Transtracheal or endotracheal aspiration cytology determines infection based on the examination of the cells present. Bronchoalveolar lavage is a test in which fluid samples of the bronchus and alveolar (lung tissue) is obtained.

    Further diagnostic testing may be needed to diagnosis a concurrent condition or eliminate other causes of similar symptoms (such as heart disease). These tests may include:

  • Bronchoscopy, which consists of placing a small flexible fiberoptic tube into the airway. This test may establish the diagnosis and rule out other diseases such as inflammatory disease, lungworms, fungal infections and neoplasia.

  • Biochemistry tests (serum blood tests) may be recommended to determine general health and check for secondary conditions.

  • Checking arterial blood gases is a method to determine oxygen levels. This sensitive test verifies the presence of significant lung disease. Many veterinary hospitals do not have the equipment to run this test but blood can be analyzed easily at a local human hospital.

  • Blood cultures may be useful to determine bacteria levels present in the blood.

  • Fine needle lung aspiration, using a fine needle or instrument to evacuate fluid or tissue by suction

  • Fecal (stool) examination may be necessary to evaluate for evidence of parasites and aid in diagnosis of lungworms

  • Conditions that are predisposed to bronchopneumonia may be evident from the history, physical and neurological examinations or may require additional studies such as a barium swallow to identify swallowing disorders and bronchoscopy to identify a bronchial foreign body. Caution: further aspiration may worsen pneumonia

    Treatment In-depth

    Treatment of bronchopneumonia is usually individualized based on the severity of your pet's condition, the cause, secondary diseases or conditions and other factors that must be analyzed by your veterinarian.

    Pneumonia can be a severe and progressive condition that causes difficulty breathing. Severely ill pets with a fever, not eating, lethargic and/or difficulty breathing may require hospitalization with oxygen, intravenous fluids and antibiotics and supportive care.

    Mildly affected pets that are well hydrated and eating properly may be treated as an outpatient with frequent follow-ups to monitor the progression of the infection.

    Treatment of bronchopneumonia may include the following:

  • Keep your pet well hydrated and warm. Fluid therapy is often required to prevent dehydration, which can cause thickening of respiratory secretions.

  • Coupage (clapping on the chest to mobilize/loosen secretions) is recommended 4 to 6 times daily. Once the patient feels better, brief walks (followed by coupage) help to mobilize tracheobronchial secretions.

  • Airway humidification may assist in expectoration (productive coughing) of secretions.

  • Expectorants like guaifenesin are of uncertain value and are not typically prescribed.

  • Bronchodilator therapy is not of proven effectiveness but may reverse irritative bronchoconstriction and strengthen respiratory muscle effort in pets having difficulty breathing.

  • Antibiotics should be prescribed for at least three weeks; duration of therapy may be longer pending clinical results and radiographs. Antibiotic choice should be based on culture and sensitivity (obtained by transtracheal washing) or on likelihood of empiric success and with consideration of current or prior antibiotic therapy. Antibiotics recommended may include cephalexin(Keflex®; Keflin®; Kefzol®), sulfadiazine-trimethoprim (Bactrim®; Septra®), enrofloxacin (Baytril®), amoxicillin-clavulanic acid (Clavamox®), tetracycline (mature dogs), chloramphenicol or cefadroxil. In life-threatening blood contamination (sepsis), the combination of intravenous cephalothin or ampicillin plus enrofloxacin should be considered. Newer generation cephalosporins (e.g. moxalactam) are very expensive and usually reserved for resistant infections.

  • Bronchodilator drugs include xanthine derivatives and beta adrenergic (sympathomimetic) agonists. Bronchodilators also may increase the vigor of contraction of the respiratory muscles, which may be useful in dogs with dyspnea. Theophylline and its various salts are most commonly chosen. Some dogs cannot tolerate the adverse effects of xanthines, which include anxiety, restlessness, tachycardia (abnormally rapid heart rate), polyuria (frequent urination) and emesis (vomiting).

  • Cough suppressants are inadvisable.

  • Humidified oxygen should be administered to dyspneic, severely cyanotic or hypoxemia pets.

  • Management of bacterial pyothorax (pus in the cavity around the lungs) requires thoracostomy tube drainage and antibiotics. Since anaerobic organisms are commonly involved in pyothorax, treatment with alone or in combination with sulfadiazine-trimethoprim or clindamycin is recommended.

  • Encourage appetite with good quality food.

    Optimal treatment for your pet requires a combination of home and professional veterinary care. Follow-up can be critical and may include the following:

  • Administer any prescribed veterinary medications as directed and be certain to contact your veterinarian if you are experiencing problems treating your pet.

  • Follow-up radiographs should be obtained to ensure resolution of infection. Areas of lung consolidation may take 2 to 6 weeks to become totally clear. Failure of steady clinical and radiographic improvement indicates a need to re-evaluate the patient and to consider a tracheal wash or bronchoscopy with bronchial fluid aspiration to determine cell analysis and bacteria causing the infection.

  • Recurrent pneumonia also is common, particularly in those animals with persistence of predisposing factors, like swallowing disorders, anticancer therapy, ciliary dyskinesis and acquired or congenital immune deficiencies. Your veterinarian may refer you to a specialist if the diagnosis is in doubt.

  • Infrequently, an unresponsive or refractory single lobe infection requires surgical lobectomy for resolution of the problem.

  • Manage predisposing causes and continue antibiotics as discussed above.

  • Your veterinarian may suggest referral for resistant cases.

  • Repeat culture and sensitivity, as needed.

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