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Pneumonia

Most people have heard the term pneumonia and know it is a lung infection of some sort. In fact, pneumonia is not a very specific term and essentially means “lung inflammation of some sort.” Pneumonia is separate from bronchitis, which means “inflamed airways of the lung,” but these two conditions commonly go together to created what is called bronchopneumonia. Pneumonia is an inflammation in deep lung tissues where oxygen is absorbed into the body and waste gases are removed. It has potential to be life-threatening regardless of its cause. Usually there is an infection at the root but not necessarily.

Pneumonia is commonly classified by its original cause:

-Fungal Pneumonia (caused by a fungus, typically Coccidioidomycosis immitis, Cryptococcus neoformans or other fungi that are particularly difficult to treat).

– Viral Pneumonia (usually the result of canine distemper virus infection or a complicated feline upper respiratory infection) .

-Parasitic Pneumonia (from lungworms directly or from the migration of other worms through the lung.)

– Bacterial Pneumonia (often secondary to severe kennel cough particularly in young puppies that have been shipped long distances, aspiration as from megaesophagus, or secondary to either of the above causes.)

– Allergic Pneumonia (the result of extreme infiltration of the lung by inflammatory cells in the absence of In most cases of pneumonia there is a bacterial component. This means that no matter what started the pneumonia, bacteria have joined in adding their own special pus, fever, and potential for disaster; in most cases, management of the bacteria is vital. This article centers on the management of bacterial pneumonia.

When to Suspect Pneumonia

The diagnosis of pneumonia hinges on the chest radiograph but knowing when to take chest radiographs can be tricky. The veterinarian must put together findings from the history, physical examination, and possibly response to initial therapies to decide if radiographs should be checked.
Coughing puppies from the pet store or shelter may have a simple kennel cough (a minor bronchitis) but they are high risk for distemper infection.

Coughing dogs or cats with a fever, listlessness, or appetite loss should definitely be radiographed for pneumonia; though many patients with pneumonia will not have fevers and some will still be deceptively active.

Coughing dogs with a history of megaesophagus or with a history of symptoms typical of megaesophagus should be radiographed for pneumonia.

Kittens with severe upper respiratory infections who do not respond to the usual management should be radiographed for pneumonia.

Coughing is hallmark symptom, though certainly not all coughing pets (or even most coughing pets) have pneumonia. Bacterial pneumonia does not just happen; it is virtually always caused by something else, so some kind of diagnostics will likely be needed to determine what led to the bacterial pneumonia if it is not readily apparent.

Treatment

The pneumonia patient may be in one of three states:

Stable (in other words, eating well and active despite a nasty cough. These patients can often be treated at home.)
Unstable (poor appetite, inactive, in need of hospitalization.)
Critical (unable to get enough oxygen into their systems. These patients require oxygen therapy and possibly 24 hour care.)

The goal is to get the patient stable enough for home treatment as several weeks are needed to fully clear pneumonia. When the patient is eating well, he or she may be discharged with oral antibiotics, a regimen of physical therapy, and a schedule for re-check radiographs (usually weekly).

The hospitalized patient has the following needs:

Intravenous fluid therapy

Coughing may be annoying but it is therapeutic and, when it comes to pneumonia, we want to encourage it, not suppress it. Coughing brings up the pus, mucus, and inflammatory cell products that make our patient sick. If the secretions of the lung are allowed to dry up, the patient will never be able to cough them up. For this reason, IV fluids must be maintained to keep our patient hydrated and keep the respiratory secretions wet.

Antibiotic therapy

Antibiotics are given to kill the bacteria, but which antibiotics should be chosen? We need something that will penetrate into the pus and mucus (which many antibiotics cannot do). Often a four quadrant approach is used that covers bacteria classified as Gram negative and Gram positive as well as those classified as aerobic and anaerobic. This typically involves two antibiotics used in combination to synergize one another.

Alternatively, the lungs may be cultured via a procedure called a tracheal wash. This process involves light sedation which the patient must be stable enough to withstand. Sample fluid from deep in the lung can be retrieved for culture. A culture identifies the organism and provides a list of antibiotics that can kill it.

If the patient is sick enough for hospitalization, antibiotics are typically given as injections so as to maximize absorption into the body.

Nebulization

This technique is becoming more and more available to small hospitals. It involves a piece of equipment called a nebulizer, which creates a mist of fine saline droplets. These droplets are far smaller than those produced by commercial vaporizers that many people have in their homes. The droplet size determines how far into the respiratory tract the moisture can be inhaled. Vaporizer droplets are typically halted in the nasal passages and throat while nebulized droplets can travel all the way into the lung. Nebulized saline may carry antibiotics with it thus providing an additional source of moisture and antibiotic for the sick lung.

Physical Therapy

A technique called coupage is helpful at mobilizing respiratory secretions. The therapist’s hand is cupped and gently but rapidly taps the patient’s chest wall repeatedly. This loosens some of the deeper secretions and helps them move into airways. Material in the airway generates coughing which removes these materials from the body. Coupage should be performed at least four times daily and should be continued at home as long as the patient has a cough.

Light exercise is also helpful in mobilizing the respiratory secretions. The patient should not be over-exerted as he/she does not have normal lung capacity but one can use one’s judgment as to what level of exercise is tolerated by the patient.

Oxygen Therapy

In most cases, oxygen therapy is not necessary but when a pneumonia patient simply cannot move enough air, there is no substitute for oxygen. Room air is 20% oxygen. An oxygen cage typically is set to deliver 40% oxygen (higher percentages over long term are actually toxic to lung cells), and special oxygen-delivery hoods are also popular. A patient who requires this level of support is extremely sick.

Home Care

Once the patient has a good appetite, he or she may be discharged for home care. The following tips are recommended as long as the patient is coughing:

Do not allow prolonged exposure to extreme cold or wet weather. Keep your pet primarily indoors.
Consider use of a vaporizer for 15 to 20 minute intervals a couple of times daily. If you do not have a vaporizer, leave the pet in the bathroom with the shower on to create a misty vapor.
Perform coupage at least 4 times daily and allow light exercise to promote the cough.
Do not try to suppress the cough with over-the-counter cough suppressants. We want the infected material in the chest to be coughed up.
Use the antibiotics as directed. Expect several weeks to be required.
Know what you should return for re-check radiographs.

 

From: THE PET HEALTH LIBRARY (http://www.veterinarypartners.com)
By Wendy C. Brooks, DVM, DipABVP

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