SMALL ANIMAL MEDICINE
FELINE
Aspiration Pneumonia
Dr Vanessa McClure BVSc
(Hons), MMedVet (Med)
[email protected]
Aspiration pneumonia (AP) is a common diagnosis
in canine patients but rarely seen in feline patients. It
occurs when a patient inhales oral and/or stomach
fluid into the respiratory tract. This process can vary
from a mild inflammatory response to a more severe
disease, depending on the composition and volume
of the aspirate. Low pH and high volume aspirates, as
well as the presence of food particles in the aspirates,
intensifies the severity of the inflammatory response.
Aspiration first results in a sterile pneumonitis,
where the damage to the airways and pulmonary
parenchyma is a direct result of the aspirated fluid.
This tissue damage triggers an inflammatory response,
resulting in necrosis of type I alveolar cells, bronchiolar
constriction, pulmonary haemorrhage, increased
mucus production, alterations in mucociliary action
and increased vascular permeability, causing oedema,
and finally alveolar collapse and atelectasis.
The injury to the epithelium in turn, enhances bacterial
adhesion, and the decrease in the mucociliary activity,
along with the airway collapse causes entrapment
of bacteria and subsequently infection, resulting in
aspiration pneumonia. The inflammatory response
in the affected lung lobe(s) can continue to progress
and cause inflammation and oedema in other
lung lobes which were not initially affected, further
compromising lung function. Most affected patients
do recover with supportive medical management, but
the mortality rates can be up to 25% in severe cases.
Diagnosis
It is difficult to make a definitive diagnosis of aspiration
pneumonia due to a lack of specific underlying
features and the fact that the aspiration events are
seldom witnessed (<1% of the time). A presumptive
diagnosis is usually based on a combination of history
(which may include a predisposing condition/event),
physical examination findings, clinical signs, and
radiographic findings.
Fig 1b
Fig 1 a: Lateral radiograph showing typical presentation of aspiration
pheumonia.
Fig 1 b: DV Thoracic view showing opacification
of the right middle lung lobe.
Issue 05 | NOVEMBER 2018 | 17