Pneumonia in Pets

Pneumonia is an inflammation of the lungs. It is rare in cats
and less common in dogs than in people. There are many types of
pneumonia, with bacterial and fungal infections being the most
common.

The dog’s lungs are not very susceptible to primary bacterial
pneumonia, but prior lung damage predisposes them to secondary
invasion by bacteria. The canine distemper virus causes severe
damage to the cells lining the respiratory tract of dogs, making
the lungs more susceptible to bacterial infection and pneumonia.

A common type of pneumonia is aspiration pneumonia, which occurs
when dogs vomit and inhale that material into their lungs.
Aspiration may occur when animals vomit after surgery because
anesthetic drugs depress the swallowing reflexes.

Aspiration pneumonia may be caused by a condition called
megaesophagus. In megaesophagus, there is abnormal movement of
the esophagus (the tube that connects the mouth with the
stomach), allowing food to accumulate instead of moving into the
stomach. This pool of food and saliva is constantly regurgitated
into the mouth and some of the material goes down the trachea
into the lungs. Some diseases of the nerves that control
swallowing can also allow entry of food into the lungs. The
inhaled food contains bacteria and sometimes stomach acid that
cause inflammation.

Dogs with pneumonia are usually brought to the veterinarian
because of coughing, loss of appetite, depression, and
difficulty breathing. They often have a fever. Lung sounds heard
with a stethoscope are increased because of the abnormal pus and
fluid in the airways.

The effort required to breathe gives an indication of the
severity of the lung infection.

Identification of the cause of the pneumonia is necessary for
optimal treatment. Chest radiographs (x-rays) are required for
accurate diagnosis of pneumonia. Fungal pneumonias have a
typical pattern of inflammation that helps differentiate them
from bacterial pneumonia. In megaesophagus, there is an enlarged
esophagus and the lung inflammation occurs in the lower part of
the lungs. Diagnosis of bacterial pneumonia secondary to
distemper is difficult. Additional tests for distemper should be
done in dogs whose vaccinations are not current. Bacterial
pneumonia can also be secondary to tumors and foreign bodies,
such as pieces of grass.

A complete blood count is helpful in assessing the severity of
the lung inflammation and identifying secondary diseases.
Obtaining pus and fluid from the airways is important in
identifying the organism causing the problem. The type of
bacteria and its antibiotic sensitivity determine the antibiotic
needed. People can cough up a sputum sample for testing, but
dogs are not as cooperative.

A procedure known as a percutaneous (going through the skin)
tracheal washing is an effective and relatively safe way to
obtain material from the trachea and bronchi. A local anesthetic
in the skin allows painless passage of a small tube through the
skin of the neck into the trachea or windpipe. Fluid is injected
through the tube to dilute the thick material in the airways,
which can be sucked into a syringe. During the 2 to 3 days
required for the bacterial test to be completed, an antibiotic
likely to be effective may be started. This antibiotic may need
to be changed when the culture results are obtained.

Antibiotics or antifungal drugs are the mainstay of bacterial
and fungal pneumonia treatment, respectively. Dogs with severe
respiratory difficulties may require oxygen treatment to improve
their breathing. Nebulization of a fine water mist can help keep
the airway moist, loosen thick mucus, and help the lungs remove
debris through coughing.

The outcome of pneumonia in dogs depends on the cause of the
pneumonia and the severity of the infection. There must be
enough lung capacity to maintain an adequate oxygen supply to
the body for at least 2 to 3 days until the antibiotics can
begin to work.

Primary pneumonias without underlying disease are usually
treated successfully. The prognosis for aspiration pneumonia
depends on the ability to correct the cause of the vomiting and
on the severity of the pneumonia. Pneumonias secondary to
distemper or similar viral diseases have a guarded prognosis. At
least half of dogs with distemper develop seizures because of
the effects of the virus on the brain.

The above is general veterinary information. Do not begin
any course of treatment without consulting your regular
veterinarian. All animals should be examined at least once every
12 months.