Lung and airway inflammation that result in respiratory distress is called pneumonia. This condition usually causes a drop in the oxygen levels in the blood. Viral and bacterial infections, parasitic infestations and the accidental entry of foreign bodies into the airways are the main causes of pneumonia in dogs. Lower respiratory tract infections in dogs, particularly canine distemper, canine influenza, adenovirus type 1 and type 2 infections make them susceptible to pneumonia because of the damage they cause to the respiratory tract.
When parasites enter the bronchi, the resulting irritation may cause pneumonia in dogs. Fungal infections also can result in this condition. Occasionally, tuberculous pneumonia occurs in dogs. Any injury inflicted on the mucous lining of the bronchi by sharp objects, or irritant substances inhaled, can be the cause of pneumonia. The dog may aspirate its own vomit, as well as food or medicines, leading to pneumonia and other bacterial infections. This often happens when the dog is force fed food or medicines or when it has persistent vomiting due to some other illness. Administration of barium or oil as part of medical procedures may accidentally lead to the aspiration of the same.
The typical symptoms of pneumonia are deep cough and difficulty in breathing. The dog may lack appetite and become lethargic. A blue tint to the mucous membrane due to oxygen deficiency in the blood is another indication. This is more obvious when the dog has to exert more, as at the time of exercise. Breathing is often labored, with a typical blowing of the lips. Slight to moderate rise in body temperature is often observed. Pneumonia may lead to pleurisy or secondary infections.
Pneumonia is diagnosed from the symptoms and the recent medical history of the dog. The veterinarian may look for typical signs of pneumonia while examining the dog’s chest, and may pick up the sound of wheezing. An x-ray of the chest may show a significant increase in the density of the lungs due to the accumulation of phlegm. Washing of the airways may provide a fluid sample for testing in the lab. If it contains any evidence of a bacterial infection, a cultural analysis and drug sensitivity test may be conducted to determine the suitable drug therapy. Viral pneumonia is usually characterized by high fever.
When the dog is diagnosed with pneumonia, it is advisable to keep it in a warm environment. Dry air is more suitable too. If oxygen deficiency is observed, the dog may be provided with supplemental oxygen. Antibiotic therapy is started immediately, without waiting for the test results. However, when the culture and sensitivity test results come, the drugs best suited for treating the specific organism can be selected. X-rays and other tests are repeated periodically to assess the progress of the treatment. They can help the veterinarian detect any complications due to secondary infections too.
As the name indicates, this type of pneumonia results when liquid or solid materials are aspirated into the lungs and the airways. The type or material and its distribution within the lungs determine the severity of the pneumonia. Medicines in the liquid form have a high probability of being aspirated, especially when they are force fed to the animal. Breathing in the vomit may introduce not only foreign material into the lungs but also bacteria that can cause infections, complicating the condition. Any difficulty in swallowing due to abnormalities in the mouth and esophagus, faulty swallowing mechanism or congestion in the food pipe due to diseases may increase the chances of aspiration while the dog eats or drinks. Anesthetized animals have a high risk of aspirating stomach contents as well as saliva during and after surgical procedures.
The usual symptoms include fever, difficulty in breathing, rapid breathing and high heart rate. A blue tint to the mucous membrane indicates oxygen deficiency in the blood. Bronchial spasms and green or brown colored nasal discharge may be present. It may be accompanied by a sickly sweet smell in the breath which intensifies with the progression of the disease. If the dog is known to have inhaled any substance, it may help the veterinarian in diagnosing aspiration pneumonia. Sometimes, the dog may cough up part of the material aspirated. Nasal discharge also may contain these substances.
Aspiration pneumonia is treated in the same way as other types of the disease, but it is often very difficult to remedy the condition. Even with the best of treatments, fatality rate is very high. Even the dogs that recover from the disease may have abscesses in the lungs. Precautions to prevent the animal from aspirating saliva or stomach contents during investigative procedures and surgeries are usually taken by the veterinarian. When it is reported that the dog has inhaled a substance, the vet may immediately start antibiotic therapy as a pre-emptive measure to avoid the development of pneumonia.
Fungal infections affecting the lungs may result in fungal pneumonia which is otherwise referred to as mycotic pneumonia. Some of the fungi causing this type of pneumonia in dogs and other domestic animals are Histoplasma capsulatum, Cryptococcus neoformans, Coccidioides immitis and Blastomyces dermatitidis, besides several species of Aspergillus.
Fungal infections are more common in dogs with a weakened immune system, but occasionally they may affect healthy individuals too. The infections result from the fungal spores that get inhaled by the animals. It may be carried to different parts of the body by the blood or by the lymphatic fluid. Soil is the main source fungal spores. Animal to animal transmission is rare.
Mycotic pneumonia does not appear suddenly. The disease develops slowly, and the symptoms begin to appear after a long time. The initial symptom is a short, productive cough, usually accompanied by a nasal discharge of thick mucus. Other symptoms of pneumonia such as respiratory distress, weight loss and lethargy may follow with the progress of the disease. In early stages, harsh respiratory sounds may be detected by the veterinarian on examining the dog, but when the disease is advanced, the sounds may be suppressed or become almost undetectable. Intermittent fever is common. Enlargement of the lymph nodes may compress the airways, further aggravating the breathing difficulty.
Fungal pneumonia is suspected if the dog that has been having the respiratory disease for a prolonged period before it starts displaying typical symptoms of pneumonia. Since antibiotics are not effective against fungi, pneumonia that does not respond to antibiotic therapy may indicate a fungal disease. X-ray of the chest and lab tests of blood as well as the fluid extracted from the airway may help in confirming fungal pneumonia.
Fungal pneumonia can be treated with anti-fungal medications, but the treatment may have to be continued for extended periods. Even after the symptoms of pneumonia subside, the drugs may have to be given for a few more months. The effectiveness of the treatment depends on the diligent observance of the veterinarian’s advice.