Aspiration pneumonia in dogs is a serious condition that requires veterinary attention and several days of intensive care. How do dogs get this condition in the first place?
Normally, food, fluids or vomit is prevented from being aspirated into the dog's lungs through natural defensive mechanisms.
However, there are certain medical conditions that can cause loss of protective reflexes.
Following is some information about aspiration pneumonia in dogs, causes, symptoms and treatment by veterinarian Dr. Ivana Crnec.
Aspiration Pneumonia in Dogs
Pulmonary aspiration is defined as inhalation of fluid and/or foreign material into the dog's airway.
The inhalation results in inflammation of the dog's airways and pulmonary tissues, known as aspiration pneumonitis.
Aspiration pneumonia, also known as inhalation pneumonia, on the other hand, refers to a bacterial infection of the pulmonary tissue that develops secondary to aspiration.
Aspiration pneumonia may develop simultaneously with aspiration pneumonitis if the aspirated fluid/particles were contaminated with bacteria. The term aspiration pneumonia in canine patients, refers to both aspiration pneumonitis and true aspiration pneumonia.
Aspiration pneumonia is therefore a severe and acute condition in which a dog's lungs become inflamed due to inhalation of foreign matter.
The aspirated content usually comes from vomit or stomach regurgitation, but may also include the forced administration of food, drugs or mineral oil. In some cases, dogs may develop aspiration pneumonia after surgery or hospitalization.
Causes of Aspiration Pneumonia in Dogs
There are several predisposing conditions for aspiration pneumonia. As mentioned, normally, dogs are prevented from aspirating foreign objects into their lungs by natural mechanisms.
Conditions that impair such mechanisms predisposes dogs to aspiration pneumonia.
Predisposing factors include localized disorders affecting the dog's ability to swallow such as neuromuscular disorders like myasthenia gravis, problems associated with the esophagus (megaesophagus, laryngeal paralysis, esophageal obstruction), cleft palates in puppies, large volumes of food/fluid in the stomach (obesity, overfeeding, pregnancy, gastrointestinal blockage, foreign body).
Aspiration pneumonia may also occur in cases where there is impaired consciousness as seen in dogs with a history of certain heavy traumas (head injuries), dogs suffering from seizures, metabolic abnormalities (severe hypokalemia, hypomagnesemia), severe debilitation, dogs undergoing surgery (heavy sedation and general anesthesia) when the swallow reflex is diminished.
Certain procedures that involve the administration of food, medications or certain compounds (like barium) through gastric feeding tubes may cause what's known as iatrogenic aspiration (medically-induced).
Dogs at Risk
Due to their conformation, certain dog breeds are predisposed to aspiration pneumonia, while other breeds are predisposed to diseases that increase the risk of aspiration.
All brachycephalic breeds (dog breeds with smooshed noses) are at high risk of aspiration pneumonia.
Their anatomy and secondary physiologic changes result in chronic upper airway obstruction. The obstruction leads to increased negative pressure in the thoracic cavity, thus increasing the risks of vomiting and regurgitation.
The brachycephalic group of dogs includes several breeds, such as: Affenpinscher, Boston terrier, boxer, bulldog, bullmastiff, Cavalier King Charles spaniel, pug, Pekingese, Tibetan spaniel, Japanese chin and Shih Tzu.
Symptoms of Aspiration Pneumonia in Dogs
Aspiration pneumonia in dogs progresses in 3 stages.
The first stage develops immediately after aspiration and results directly from the damage the inhaled content causes.
The first stage includes damage of the pulmonary tissue, inflammation and necrosis.
The second stage begins 4-6 hours after the aspiration, lasts for 12-48 hours and is characterized by the body’s response to inflammation.
The third stage involves bacterial colonization of the airways and pulmonary tissue.
Common signs that indicate aspiration pneumonia include rapid breathing or difficulties breathing, stretching of the neck, noisy or wet breathing, runny nose, fast heart rate, coughing or wheezing, loss of appetite, lethargy, fever, blue colored gums and collapse.
At the Vet's Office
Unfortunately most of the signs associated with aspiration pneumonia are non-specific.
Regardless, the vet will need the dog’s complete history. After questioning the owner the vet will start his diagnostics by performing a thorough physical examination.
The physical examination must include auscultation of the lungs (using a stethoscope to listen for abnormal lung sounds).
Then additional tests need to be performed.
Those tests include chest x-ray (to see the condition of the lungs), abdominal x-ray (to look for the reason for vomiting/regurgitation), blood analyzes (to check if the leukocytes’ levels are increased due to inflammation), pulse oximetry (to measure the oxygen levels in the blood or lungs)
Based on these tests, the vet may set a preliminary diagnosis. Definitive diagnosis of aspiration pneumonia is based on cytology and bacterial culture of pulmonary fluid.
Aspiration pneumonia is a life-threatening condition that requires aggressive approach, several days of intensive care and few weeks of at-home treatment, as well as regular check-ups.
The treatment includes oxygen therapy, intravenously administered fluids, intravenously administered antibiotics, anti-vomiting medications, bronchodilators or lung expanders and cage rest.
When the dog is stable and capable of breathing without support it can be sent at home. At home, the dog should be given oral antibiotics for up to 3 to 5 weeks.
During this period, the dog needs control chest x-rays at least once a week. The antibiotic therapy should end one week after the abnormal x-ray patterns have dissolved.
The prognosis depends on the severity of the condition or the extent of the pneumonia as well as on the early diagnosis and treatment. Sadly even with early and appropriate treatment, dogs suffering from aspiration pneumonia have poor prognosis.
Dog Aspiration Pneumonia Costs
Due to hospitalization and intensive care, treating canine patients with aspiration pneumonia is significantly expensive.
The exact cost depends on the underlying cause that induced the condition.
Simpler cases of aspiration pneumonia in dogs may cost between $200 and $400.
However, the total cost cannot be estimated without knowing the cause. Some causes or risk factors require surgical measures which significantly increase the expenses.
Preventing aspiration pneumonia is much easier (and less costly!) than treating it. Proper prevention involves identifying patients at risk and taking appropriate steps to protect these patients by decreasing the corresponding risk factor.
Since most of the aspiration pneumonia cases occur after anesthesia when the dog frequently vomits, veterinarians recommend fasting prior to surgery. For owners that administer oral medications at home, it is important to find balance between the speed of administering and the dog’s ability to swallow.
- Kogan DA, Johnson LR, Sturges BK, et al. Etiology and clinical outcome in dogs with aspiration pneumonia: 88 cases (2004-2006). J Am Vet Med Assoc2008;233(11):1748-1755.