By Dr. Becker
Not long ago I did a video about aspiration pneumonia, also called inhalation pneumonia, which can result when an animal, more commonly a dog, inhales solid or liquid foreign material into the lungs, creating an inflammatory condition that results in a lung infection.
This week I’d like to discuss two other types of pneumonia in pets, bacterial pneumonia and fungal pneumonia.
Bacterial pneumonia is inflammation characterized by cells and fluid that accumulate in the lungs, airways, and alveoli. The cause, as you might expect, is pathogenic bacteria. The condition is more often seen in dogs than cats and is more prevalent in sporting dogs, hounds, and large mixed-breed dogs.
No single type of pathogen is responsible for bacterial pneumonia, though there are some organisms more frequently seen than others in both dogs and cats. In dogs, Bordetella bronchiseptica and Streptococcus zooepidemicus are usually the culprits.
In cats, it’s Bordetella bronchiseptica, Pasteurella, and Moraxella that are more commonly cultured. But other organisms, including anaerobic bacteria, can also cause infection.
Conditions that seem to predispose some pets to bacterial pneumonia include a preexisting viral infection, problems swallowing, regurgitation, and metabolic disorders.
Symptoms of bacterial pneumonia include cough, fever, breathing difficulties ─ including rapid breathing ─ loss of appetite, weight loss, lethargy, a nasal discharge, dehydration, and exercise intolerance.
When your vet listens to your pet’s lungs with a stethoscope, he may hear abnormal breathing sounds known as crackles (which are short, snapping sounds), as well as some whistling or maybe even wheezing.
If your vet suspects bacterial pneumonia, he may perform a transtracheal wash to obtain material from the lining of the trachea for analysis, including cytology and a culture and sensitivity test. X-rays of the chest and lungs may also be ordered along with a blood test to check for systemic infection.
Antibiotic therapy will be needed in confirmed cases of bacterial pneumonia. The proper medication can be selected from the results of the bacterial cultures. If there are other symptoms like loss of appetite, those will also need to be addressed.
Pets in respiratory distress may need oxygen therapy. IV fluids are also sometimes ordered to either treat or prevent dehydration.
While he recovers, your pet will need plenty of rest. Exercise should be limited to physiotherapy and activities to help clear the lungs and airways.
Even though your pet will need lots of rest, you must ensure she doesn’t lie in one position too long to allow fluid buildup on one side of the lungs or the other. You should encourage her to change positions often while she’s resting.
During the recovery period, I recommend supportive therapies, including antioxidants -- specifically vitamin C and N-acetylcysteine -- as well as lung-specific nutraceuticals.
Many pets have a full recovery from bacterial pneumonia when treated appropriately and promptly. Most deaths from pneumonia result from secondary complications, including hypoxemia (severely low levels of oxygen in the blood) and sepsis, which occurs when a localized lung infection spreads throughout the body.
Fungal pneumonia is a whole different beast. This lung infection is a result of a deep fungal infection, sometimes called a mycotic infection. The inflammation caused by this type of infection can develop in the interstitial tissues, the lymphatic vessels, or in the peribronchial tissues of the lungs.
Like bacterial pneumonia, fungal pneumonia is more commonly seen in dogs than cats. Some breeds are more susceptible than others. For example, the German Shepherd. Male dogs are two to four times more likely to acquire this type of pneumonia than female dogs.
There are several types of fungi that can cause lung fungal infections, including Blastomyces, Histoplasma, and Aspergillus. Exposure to infection-causing fungi can happen through contact with soil that’s rich in organic matter, bird droppings, or feces.
The method of contraction depends on the type of fungus. For example, some fungi enter the body through inhalation via the mouth and others enter through the nasal cavity.
Symptoms of fungal pneumonia include loss of appetite, weight loss, fever, runny eyes or a runny nose, coughing, difficulty breathing, eye problems, and sometimes lameness. Your vet may also hear abnormal lung sounds during an examination, but oddly, often a fungal infection will first present as an eye or skin problem.
The only way to definitively diagnose fungal pneumonia is to analyze the fluid collected on a transtracheal wash. If there are skin lesions present, performing a fine needle aspirate, lumpectomy, or biopsy of an enlarged lymph node can also yield the diagnosis of fungal infection. Other tests your vet may want to run include a urinalysis, X-rays of the chest and lungs, a fungal PCR assay, and an abdominal ultrasound.
Sadly, many dogs and an even greater percentage of cats are unresponsive to fungal pneumonia medication. In addition, treatment is very expensive and can last for two to six months or sometimes longer. The exact treatment depends on the type of fungus that has caused the infection.
Because fungal pneumonia can develop from dogs sniffing around in the wrong place at the wrong time and inhaling a whopping dose of fungi from the environment, discouraging dogs from digging at organic debris can help reduce the risk of acquiring fungal infections.