Pneumonia is most probably the common disease of respiratory system in dog beside Kennel Cough.To know about pneumonia we have to understand some basics about respiratory system.
What is we understand by respiratory system?
The respiratory system is one where oxygen is exchanged with carbon dioxide in the body. In general , this system is divided into two parts. The upper respiratory tract which consist of nose, nasal sinus, throat and trachea(wind pipe) while the lower respiratory tract consist of small airways(bronchi and bronchioles) and the alveoli ( the small air sac where oxygen exchange occurs)
What is Pneumonia?
In simple terms, Pneumonia is inflammation of lungs and air ways. Inflammation (from Latin : niflamatis is part of complex biological response of body tissue to harmful stimuli, such as pathogen, damaged cell or irritant and is a protective response involving cells, blood vessel, and molecular mediator. Pneumonia causes difficulty in breathing and deficiency of oxygen in body. These symptoms disappear with proper treatment but if not treated timely it could lead to serious complication like hypoxemia and sepsis.
What causes Pneumonia?
There are many possible causes of pneumonia in dogs. The most common one is viral infection of lower respiratory tract. Few example of these viruses are canine distemper virus, adenovirus type 1 and 2 , canine influenza virus and Para influenza virus. These viruses damage the airway which make the dog more susceptible to development of pneumonia .Beside the viral attack make the secondary bacterial infection more likely.
Similarly another common causes of most pneumonia in dog is bacterial infection caused by Bordetella bronchiseptica, Escherichia coli, Pseudomonas aerugenosa, Pasteurella multocida and Mycoplasma species to name a few. B. bronchisepeptica is highly contagious and may spread to other dog easily and rapidly causing Kennel cough especially in young and old dogs, or dogs with compromised immune system. However most other bacterial pneumonia are not particularly contagious to other dogs.
In other cases irritant like tobacco smoke, smog, or other inhalant pollutant may be the underlying cause that predisposed the dogs to bacterial infection. Tuberculosis pneumonia is also sometime seen in dogs though the cases are very rare.
Fungal pneumonia (also called mycotic pneumonia) in which there is fungal infection in lung leading to development of pneumonia .Major fungal pneumonia are caused by Aspergillus species, Candida species, Histoplasma capsulatum etc. Infection is caused by inhalation of spores.
Besides the above mentioned causes there is one important cause of pneumonia called Aspiratory pneumonia. It is seen in dogs who has persistent vomiting, abnormal movement of esophagus (food pipe) , improperly administration of medicine or force feeding where the content is accidently enter into trachea of dog.
What are signs of Pneumonia in dogs?
Signs are generally appears in respiratory system.
Some of the major sign are
In aspiratory pneumonia beside above symptoms, dog may also exhibit sign of difficult swolling bluish skin and frequent regurgitation.
How diagnosis is made?
The vet will perform through physical examination of the dogs body along with listening (auscultation) the lung with stethoscope .Beside this he will take a through history from client and runs a appropriate test. The vet will generally hear wheezing (breathing with a whistling or rattling sound in chest) within the lungs. It is heard most clearly when dog exhaled but in severe cases it can be heard when exhaled. It is caused by narrowed airway or inflammation.
In the later stages of Pneumonia the increased density of lung caused by inflammation can be seen in X-ray. Analysis of fluid used to wash the airway is also valuable to diagnose bacterial infection. A viral infection generally results in an increased body temperature.
A tentative diagnosis of fungal pneumonia can be made if the animal has long term respiratory disease and exhibit typical sign such as short moist cough (characteristic sign) and thick discharge from nose. In fungal pneumonia, the dog doesn’t respond to antibiotic therapy. However for definitive diagnosis the vet require identification of fungus using appropriate laboratory test like fungal culture, X-ray and blood test.
For the diagnosis of aspiratory pneumonia, inhalation of foreign substance or fluid/ food is a important clue to diagnose the disease.
What are the treatment options?
For bacterial pneumonia antibiotic treatment is generally started after determining the result of culture and sensitivity test. From the bacterial culture the vet will able to determine which particular bacteria species causes the infection and sensitivity test which antibiotic will be best to combat the infection. Since it takes time to get result for culture and sensitivity so in general the vet may begin the treatment with broad spectrum antibiotic like amoxicillin or doxycycline,while awaiting the test result. Once the result arrives, the vet change the antibiotic for better recovery. The animal needs to be reexamined regularly/frequently and periodic X-ray of chest should be taken in order to see the improvement of disease or reoccurrence. The X-ray also reveals if there is underlying disease or to detect any possible complication. So periodic X- ray is very important.
In the case of aspiratory pneumonia, the vet will attempt to remove the foreign material from lung that is causing the problem. They can do this through suction or other means. In some cases there is necessary for hospitalization. Oxygen therapy is necessary as well as beneficial in case of serious problem. Dehydrated dog are put on intravenous fluid to correct the dehydration and electrolyte imbalance.Additional treatment such as bronchodilator such as theophylline , Salbutamol and nebulization may be necessary. Bronchodilator are type of medication thacle in lungs and widening the airway(bronchi) .In nebulization, a nebulizer which is a piece of medical equipment which turns liquid medicine into very fine mist so that the dog can inhale it through mask or mouthpiece.
Antifungal drugs are used to treat fungal pneumonia. Extended drug theray which can be needed for several months even after signs have been resolved is generally necessary as relapses are likely.
Animal with pneumonia benefit from warm, dry environment. Rest is also a key important factor for the recovery. Other cases of pneumonia are treated based on causes..In some cases, veterinarian may need to remove damaged tissue surgically.
Even after the discharged from hospital regular follow up visit to vet is necessary for his valuable checkup and guidance.
Dr. Pratik Man Pradhan
Mount Everest Kennel Club