Dyspnea (Trouble Breathing) in Dogs


A detailed list of potential causes of dyspnea include:

Mechanical Disorders Causing Airway Obstruction

  • Obstructed nostrils or nasal cavity
  • Pharyngeal (throat) disorder, such as post-nasal drip, overlong soft palate, pharyngeal polyps (cysts)
  • Hair, hairballs or foreign bodies
  • Laryngeal (voice box) diseases, including paralysis; granuloma, polyp or tumor; trauma; edema (abnormal accumulation of fluid in tissues)
  • Aspiration of liquid or solid into the lungs
  • Tracheal (windpipe) diseases. Collapse or hypoplasia (incomplete development of trachea), foreign body, trauma/hematoma (blood clot), compression from thyroid mass lesion
  • Primary bronchial collapse (collapse of airways)
  • Bronchial compression from hilar lymphadenopathy
  • Bronchial foreign body
  • Trauma to the bronchopulmonary tree

    Non-infectious Inflammatory Causes

  • Bronchitis. Idiopathic (occurring without known cause), allergic
  • Bronchiectasis, which is chronic dilatation of the bronchi and bronchioles with secondary infection
  • Pulmonary granulomatosis, which is a collection of tumor-like masses in the lungs
  • Pulmonary infiltrates (foreign bodies in the lungs) with eosinophilia (collection of specific white blood cells in the blood)
  • Inhalation of noxious gases or smoke
  • Alveolitis (inflammation of the walls of the alveoli in the lungs) leading to pulmonary fibrosis
  • Infectious Causes of Respiratory or Thoracic Disease

    • Viral, including infectious tracheobronchitis, viral pneumonia
    • Rickettsial infections, which is a type of parasite
    • Bacterial infections, including pharyngitis (infection of the voice box), tonsillitis (infection of the tonsils), bronchitis (infection of the breathing tubes/airways), pneumonia, lung abscess (growth, cysts and tumors)
    • Mycoplasma pneumonia
    • Toxoplasmosis, which is a contagious disease caused by a parasite
    • Systemic mycosis, which is any disease caused by fungi, including histoplasmosis, blastomycosis and coccidioidomycosis
    • Osleri osleri, including nematodes and traveling parasites
    • Lungworms
    • Larval migrans, which is migration of parasites through the lung
    • Dirofilariasis, which is infection with heartworms


    Other Causes to Trouble Breathing in Dogs

    • Bronchopulmonary dysplasia, which is abnormal development of adult cells
    • Acidosis
    • Anemia, hypoxemia or hemoglobin abnormality
    • Neurologic (brain, spinal cord) lesions that alter ventilation
    • Neuromuscular weakness or disease
    • Rupture or paralysis of the diaphragm, including diaphragmatic hernia
    • Flail chest or rib fractures
    • Severe ascites or abdominal space occupying lesion
    • Drugs, such as steroids that may cause panting, phenobarbital, preservatives in injectables

    Lung Disorders

    • Pneumonia
    • Pulmonary edema from electrocution, airway obstruction, seizures, smoke inhalation, aspiration of gastric contents into the lungs, pulmonary embolism (the sudden blocking of an artery by a clot or foreign material), heartworm thrombus, drug reaction, uremia (an excess of waste products in the blood when the kidneys are not working properly) and DIC (disseminated intravascular coagulation)
    • Pulmonary hemorrhage (heavy bleeding into the lung) from trauma; rodenticide coagulopathy, which is a disorder of blood coagulation due to ingestion of rodent poison; DIC; disseminated pulmonary neoplasia (tumor)
    • Pulmonary fibrosis (scarring of lung tissue)

    Tumors and Mass Lesions

    • Nasal tumor
    • Pharyngeal/tonsillar tumor or polyps
    • Laryngeal tumor or polyp
    • Chondromatous hematoma of the trachea
    • Tracheal adenocarcinoma (cancer)
    • Lymphoma (cancer of lymphoid tissue) in the respiratory tree, lung, mediastinum or lymphatics
    • Thymoma (disease or cancer of the thymus)
    • Primary lung tumors (carcinomas)
    • Metastatic (pertaining to the transfer of disease from one organ or part to another not directly related to it) lung tumors
    • Cardiac or heartbase tumors

    Cardiac and Vascular Diseases

    • Left bronchial compression from left atrial dilatation
    • Left-sided congestive heart failure (pulmonary edema and/or pleural effusion)
    • Heartworm disease (canine)
    • Pericardial disease (disease of the sac enclosing the heart and the roots of the great vessels)
    • Heartbase tumors
    • Pulmonary thromboembolism (blood clot in the lungs)
    • Air embolism (e.g. with IV lines or urinary negative contrast studies)

    Diseases of the Mediastinum and of the Pleural Space

    • Mediastinal mass, which is a mass in the tissues and organs separating the two lungs, including lymphoma, thymoma and teratoma
    • Thymic hemorrhage
    • Hilar lymphadenopathy (disease of the lymph nodes) with bronchial compression. These include mycosis (any disease caused by fungi), granulomatous lung diseases, lymphoma and other neoplasms.
    • Pleural effusion caused by:

      – Congestive heart failure (CHF)
      – Hydrothorax (fluid in the pleural cavity that encases the lungs and thoracic cavity)
      Chylothorax (milky fluid in the chest)
      – Hemothorax (collection of blood in the chest)
      Pyothorax (accumulation of pus in the chest)
      Pneumothorax (entry of air into the chest)
      – Metastatic neoplasia (tumor)
      – Pleuropneumonia (pneumonia accompanied by inflammation of the pleura)
      – Pulmonary embolism
      – Diffuse lymphatic dysplasia
      – Protein losing enteropathy (disease of the intestine)
      – Idiopathic pleuritis
      – Idiopathic pleural effusion

    A complete medical history and physical examination should be performed by your veterinarian. These diagnostic tests depend on the duration of signs, presence of other abnormalities, and what is found on the physical examination. They may include:

    • Complete medical history and physical examination with emphasis on stethoscope examination (auscultation) of the heart and lungs. Identification of abnormal heart sounds such as heart murmurs or irregular heart rhythms (arrhythmia) is extremely important. During physical examination, your veterinarian will pay particular attention to your pet’s breathing, the character of his/her heart and lung sounds, and mucous membrane color. Care must be taken not to stress your dog during the examination. Your dog should also be evaluated for weight loss and any concurrent disease.


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