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Tag: Laryngeal Paralysis

  • Rat bait’s sneaky trick: bleeding into the dorsal tracheal membrane

    Rat bait’s sneaky trick: bleeding into the dorsal tracheal membrane

    Most of us are familiar with anticoagulant rodenticide toxicosis and the range of clinical signs it can present with, but there is one potentially fatal manifestation of coagulation pathology that is perhaps not as widely known…

    Dogs with severe clotting problems will occasionally bleed into the dorsal tracheal membrane. This causes collapse of the thoracic trachea and can lead to severe respiratory distress.

    Presenting signs

    These cases can present with none of the other signs of bleeding normally associated with coagulopathies, so rat bait poisoning may not come to mind as a differential diagnosis if you are not aware of this syndrome.

    The typical case will present as an otherwise healthy dog that develops acute respiratory problems. Early signs can be as mild as a persistent cough, but it can quickly escalate into a life-threatening respiratory crisis.

    Severe cases will have an obvious stridor on both inspiration and expiration, cyanotic mucous membranes, and patients may be very distressed.

    It will look very much like:

    • a dog that is choking from a tracheal foreign body
    • an old dog with tracheal collapse
    • the end stages of laryngeal paralysis – except the stridor will come from much lower in the respiratory tract than it does in laryngeal paralysis

    So, what do you do?

    On initial presentation you would approach it as any respiratory distress case: oxygen, oxygen, oxygen, calm and stress-free handling, and light sedation (butorphanol, for example).

    bleeding_dorsal-tracheal-membrane

    Once it is safe to do so, you should take chest rads to look for what you’ll probably suspect is a tracheal foreign body, and you’ll get an image like the one above (although it may not be this severe). Then you’ll remember this article, have an “aha!” moment and run a clotting profile (but if it’s as bad as this case, you’ll obviously first save the animal’s life by passing an ET tube).

    Once a clotting problem is confirmed you’ll need to stop the bleeding with standard therapy for anticoagulant rodenticide toxicity: plasma and vitamin K.

    Severe cases

    In a severe case you may need to keep the dog intubated for several hours, until the clotting times have normalised, before cautiously attempting to extubate.

    If the patient is unable to stay well oxygenated without an ET tube (mucous membrane colour, pulse oximetry, blood gas), consider placing a long oxygen catheter past the narrowing – either via a tracheostomy or a nasal O2 catheter.

    If these cases are quickly recognised for what they are, and an open airway can be maintained, the prognosis should be good. These are potentially very satisfying cases with great potential for you to be a total hero.

  • Laryngeal paralysis

    Laryngeal paralysis

    This patient was brought to us for exercise intolerance, breathing difficulty and loud airway sounds.

    The patient has laryngeal paralysis. This is where the muscles controlling the arytenoids cartilages do not work and leads to failure of opening of the arytenoids during inspiration.

    Most commonly seen in middle-aged large breed dogs, it can occur acutely, but more often it is a chronic problem exacerbated by heat or stress. The cause is often unknown, but it can be caused by trauma or lesion to the cervical region or some kind of neuropathy, such as myasthenia gravis or tick paralysis. Diagnosis is based on visualisation of the arytenoid cartilages failing to abduct during inspiration under light anaesthesia.

    Treatment

    The management of the acute presentations include oxygen and sedation (butorphanol) to improve airway dynamics – with or without active cooling triggered by heat and with or without anti-inflammatories (dexamethasone) to reduce swelling secondary to airway turbulence.

    Patients in severe respiratory distress, anaesthesia and intubation may be required for a short period. Long-term management involves either surgery, such as laryngeal tieback, or conservative management strategies that involve weight loss, avoiding exercise and being kept in a cool environment.