Page 30 - BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery, 2nd Edition

Chapter 2 · Emergency management of respiratory distress

supportive, with oxygen supplementation and diuretics Aspiration pneumonia
(furosemide 2–4 mg/kg i.v. q6–8h). Animals with upper air- Aspiration pneumonia is a relatively common cause of
VetBooks.ir affected by pulmonary oedema than those with seizures or respiratory distress in animals that are vomiting and recum-
way obstruction or head trauma tend to be more severely
bent. This is primarily diagnosed based on the radio -
those that have been electrocuted. Some animals require
graphic appearance of interstitial/alveolar infiltrates in the
positive pressure ventilation and synthetic colloid support
because of the severity of the pulmonary oedema and cranioventral and right middle lung lobe areas, as well as
tracheal wash cytology and culture. Treatment includes
the massive loss of high-protein fluid into the lungs; these oxygen supplementation, nebulization and coupage, main-
animals have a poor prognosis and usually die. Most tenance of hydration, broad-spectrum antibiotics (ideally
animals with neurogenic pulmonary oedema have either
based on culture and sensitivity testing) and mild exercise
substantially improved or have died from respiratory com- (walking) if possible. In addition, diagnostics and therapy
promise within 48 hours of the inciting event.
should also be directed at the underlying cause of the
vomiting or regurgitation.
Haemorrhage
Spontaneous pulmonary haemorrhage is most commonly Pulmonary contusion
due to intoxication with a rodenticide anticoagulant or to
thrombocytopenia. Supportive care, with oxygen supple- Pulmonary contusions vary from mild to severe, causing
mild to severe respiratory distress. Increased lower airway
mentation and specific treatment of the underlying cause,
is the only option available to treat this problem. Infection sounds and/or crackles are often heard on auscultation.
Some dogs with severe contusions will have a soft cough
with Angiostrongylus vasorum should be also be consid-
ered in dogs with haemoptysis and respiratory distress. at presentation and some may show haemoptysis. Pul-
monary contusions tend to worsen over the first 12 hours.
In addition, radiographic signs will lag behind clinical signs
Pulmonary thromboembolism
by several hours. Treatment for pulmonary contusions is
PTE can result in relatively mild to extreme respiratory primarily supportive, with oxygen supplementation and
distress. It is often associated with diseases such as hyper- judicious fluid therapy (only if resuscitation with fluids for
adrenocorticism, immune-mediated haemolytic anaemia, other problems is necessary, e.g. hypovolaemia). Res-
protein-losing nephropathy or chronic high-dose cortico- piratory signs tend to start improving after about 36–48
steroid administration. Ante-mortem definitive diagnosis hours in most cases.
can usually only be achieved by pulmonary angio graphy or
contrast computed tomography, tools that are not readily Smoke inhalation
accessible to most veterinary surgeons (veter inarians) in
practice. Therefore, the diagnosis is most commonly Smoke inhalation is a relatively rare problem. In large
arrived at using the medical history, recognition of concur- cities, smoke inhalation tends to occur in the colder
rent diseases or drug therapies that are commonly asso- months of the year, when the majority of house fires occur.
ciated with PTE, a history of sudden onset of respiratory Affected animals present with a wide range of physio-
abnormalities, and thoracic radiography. Radiographs vary logical compromise. Most have only minor respiratory
from almost normal to showing a patchy interstitial or alve- signs or ocular irritation but some may have severe respir-
olar pattern and/or mild pleural effusion. PTE should be atory and neurological compromise that can result in
considered in dogs with severe respiratory distress (not death. Respiratory signs occur as a result of swelling of
due to upper airway disease) that have normal-appearing the upper airways from direct heat injury, as well as
thoracic radiographs. Treatment for PTE is primarily sup- bronchoconstriction and pulmonary inflammation due to
portive, with oxygen supplementation, heparin therapy and chemical and particulate irritation of the lower airways and
specific therapy for the associated cause. Thrombolytic alveoli. Radiographic changes seen in dogs and cats with
therapy can be used but the authors have had limited expe- smoke inhalation vary, and include bronchiolar, interstitial
rience with this treatment. and alveolar patterns. Rarely, a collapsed lung lobe may
occur as result of bronchial obstruction from mucosal
Feline asthma swelling, sloughing and debris. Treatment for smoke
inhalation is primarily supportive, with oxygen supplemen-
Feline asthma is an airway hypersensitivity condition in tation, bronchodilators and maintenance of hydration
cats that results in bronchoconstriction, pulmonary air (whilst avoiding overhydration), with nebulization and
trapping and increased respiratory secretions. The coupage if the lower airways are found to be affected.
degree of respiratory distress can be mild to life-threat-
ening. Many owners describe their cat as retching or
coughing, and some incorrectly think that their cat is Acute respiratory distress syndrome
vomiting. Most cats have a prolonged expiratory phase ARDS is recognized in dogs and cats. It is an inflammatory
with end-expir atory wheezes heard on auscultation. condition of the lungs, resulting in severe respiratory com -
Rarely, a cat will present with a ‘barrel’ chest secondary promise with hypoxaemia and decreased pulmonary
to severe airway trapping. In this instance, airway sounds compliance. It is characterized clinically by bilateral pulmo-
cannot be auscultated because the animal is moving so nary infiltrates (on thoracic radiography) and hypoxaemia
little air. Emergency therapy for cats with asthma and with normal heart function. Therefore, clinically, any of the
respiratory distress includes oxygen supplementation, non-cardiogenic pulmonary conditions could be classified
corticosteroids (dexamethasone sodium phosphate as ARDS, but there are also certain histological character-
0.2 mg/kg i.v. or i.m.) and terbutaline (0.01 mg/kg i.m. or istics that are recognized. ARDS can be an end-stage pro-
s.c.). The authors have also used inhaled corticosteroids cess secondary to almost any inflammatory condition within
and bronchodilators in some cats. Improvement in res- the lungs or any inflammatory condition remote from the
piratory rate and effort is usually noted within 30–60 lungs, such as pancreatitis, sepsis and trauma. Treatment
minutes after terbutaline injection or inhalation therapy. is primarily supportive whilt the associated cause is treated.

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