Cyanosis in Dogs

Cyanosis (Blue Coloration) in Dogs

By: Dr. Arnold Plotnick

Section: Information In-depth


Causes

Causes of peripheral cyanosis include:

  • Anything that would cause central cyanosis, with resultant bluish coloration in all peripheral tissues.

  • Hypothermia. The low body temperature constricts the vessels in the skin.

  • Thromboembolism, or a blood clot

  • Application of a tourniquet (accidental, deliberate or malicious)

  • Shock (inadequate blood flow to the tissues)

    Causes of central cyanosis would include:

    Heart Causes

  • Congenital heart disease

  • Tetralogy of Fallot, which is a genetic defect involving four abnormalities of the heart and great vessels

  • Atrial septal defect (the proverbial "hole in the heart"), with subsequent right-to-left shunting

  • Ventricular septal defect ("hole in the heart") with subsequent right-to-left shunting

  • Reversed patent ductus arteriosus (this congenital defect does not initially cause cyanosis.
    Only if it goes undetected or untreated so that blood flow in the heart reverses, can changes occur that lead to cyanosis)

    Lung Causes

  • Hypoventilation (inability to breathe properly)

  • Pleural effusion (blood, pus, lymphatic fluid, cancer-induced fluid, etc. that gathers in the chest cavity and prevents the lungs from expanding properly)

  • Pneumothorax

  • Respiratory muscle failure

  • Muscle disorder (like a diaphragmatic hernia)

  • Neurologic disease

  • Anesthetic overdose

  • Airway obstruction

  • Laryngeal paralysis

  • Tumor, abscess, granuloma, foreign body obstructing a large airway

  • Inadequate oxygen due to improperly administered anesthesia

  • Ventilation-perfusion mismatch (improper blood supply to the lung, combined with improper lung function, or both)

  • Pulmonary thromboembolism (blood clot in the lungs)

  • Infiltration of the lung tissue with fluid (edema)

  • Inflammatory cells (infection, inflammation)

  • Cancer cells

  • Acute respiratory distress syndrome (ARDS)

  • Pulmonary fibrosis (pulmonary scar tissue)

    Other Causes

    Abnormal hemoglobin (methemoglobin) can result in cyanosis due to chemicals that render the hemoglobin nonfunctional.

  • Nitrates

  • Nitrites

  • Acetaminophen (Tylenol®)

  • Methylene blue

  • Cetacaine

  • Topical benzocaine

     
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