Horse Side Vet Guide ®

Equine Health Resource

Rapid Breathing, Flaring Nostrils at Rest (Not after Exercise)

Code Red - Call Your Vet Immediately, Even Outside Business Hours

Code Red - Call Your Vet Immediately, Even Outside Business Hours

    Breathing rate is regulated by the brainstem, which responds to the levels of CO2 and Oxygen present in the blood. Rapid breathing is the body’s attempt to increase gas exchange in the lungs, it is also a response to overheating, stress and pain.

    Rapid breathing that is not associated with recent exercise is commonly seen in horses suffering from severe disease processes including heaves Recurrent Airway Obstruction (RAO), allergic reaction (anaphylaxis), exhaustion or heat stroke. Horses in end-stage shock that is caused by any number of severe illnesses or injuries (major blood loss, pain, metabolic problems, or heart failure) may breathe or pant heavily.


    Horses exhibiting this sign may be experiencing a life-threatening crisis. Keep the horse quiet and calm and contact your vet immediately. Perform the Whole Horse Exam, paying particular attention rectal temperature, and to the presence or absence of excessive respiratory noise. this may give a clue as to whether there is an upper airway obstruction. Assess the horse’s gum color, which reflect tissue oxygenation status. Are they bluish, pink or red? Regardless, this is a veterinary emergency.


    Your vet uses history and physical exam findings to try to determine what is responsible for the rapid breathing.

    Identify or Rule-Out Possible CausesDIAGNOSES

    Recurrent Airway Obstruction, RAO
    Pneumonia, Pleuropneumonia & Pleuritis, Generally
    Foal Pneumonia, Rhodococcus equi
    Acute Systemic Disease, Generally
    Acute Respiratory Distress Syndrome, ARDS
    Ruptured Uterine Artery, Post-Partum Hemorrhage
    Fracture of Base of Skull & Brain Case
    Red Maple Leaf Toxicosis
    Equine Piroplasmosis, EP
    Atrial Fibrillation
    Rodenticide Toxicity, Generally
    Smoke Inhalation, Pneumonitis
    Respiratory Conditions, Generally
    Conditions Affecting Red Blood Cells, Generally
    Equine Infectious Anemia, EIA
    Clostridial Muscle & Fascia Infection (Myonecrosis)
    Anhidrosis, Dry Coat Syndrome
    Duodenitis-Proximal Jejunitis, DPJ
    Neonatal Isoerythrolysis in Newborn Foal
    Anemia, Generally
    Autoimmune Hemolytic Anemia
    Pulmonary Edema
    Cyanide Toxicity from Plants
    Enteritis, Acute
    Fractured or Broken Ribs (in Adult)
    Summer Pasture-Associated Obstructive Pulmonary Disease, SPAOPD
    Kidney Failure, Acute Renal Failure
    Pharyngeal Sub-Epiglottic Cyst
    Pneumothorax & Pneumomediastinum
    Monensin Toxicity
    Black Walnut Shavings Toxicity
    Colic, Sand Accumulation or Impaction
    Congestive Heart Failure, CHF
    Colic, Undiagnosed Conditions Causing
    Iron Deficiency, Caused by Anemia Caused
    Poisoning by Cardiotoxic Plants, Generally
    Nitrate Toxicity From Plants or Fertilizer
    African Horse Sickness, AHS
    Johnson or Sudan Grass Toxicity
    Jimsonweed Toxicity
    Foal or Newborn, Combined Immunodeficiency, CID
    Clotting Factor Deficiency, Coagulation Problem
    Hypocalcemic Tetany
    Oleander Toxicity
    Nasal Septum Deviation, Abnormalities
    Larkspur, Monkshood Toxicity

    POSSIBLE TREATMENTS or TherapiesTo Lessen or Resolve the Sign

    Author: Doug Thal DVM Dipl. ABVP


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