Since the symptoms of asthma in dogs are relatively general, it's very important for a veterinarian to follow certain procedures to positively diagnose a dog for asthma. There are many other medical conditions that may produce similar symptoms, and a mis-diagnosis could cause further aggravation of an existing medical condition, if mis-treated.
Asthma is most commonly classified as a symptom of an allergic reaction, and the cause of a dog's asthmatic reaction will also need to be identified (though this is often done by pet owners, after the veterinary diagnosis).
This is a standard part of a veterinary diagnosis. A veterinarian will examine a dog's heart, listen to their breathing, examine the mouth, and probably take their temperature. While these may seem like very basic procedures, they are all important in helping a veterinarian to diagnose a dog's condition.
In most cases, dogs with asthma will have one or several symptoms that gave enough reason for a dog owner to bring their dog in for a veterinary check-up. A veterinarian may also take a dog's health history at this time, as well as any changes in diet, location, or habits of the dog being examined. All of these factors will enable a veterinarian to use deductive reasoning, and make it much easier to form a positive diagnosis.
Because many of the symptoms of asthma in dogs could possibly be indicative of several other medical conditions, a veterinarian may have to first eliminate the possibility of these conditions. Other conditions that may mimic asthmatic symptoms include: leukemia, lungworm, respiratory infection, heart disease and canine heartworm. Depending on a dog's specific symptoms, a veterinarian may first run tests for other similar conditions before forming a positive diagnosis for asthma in a dog. This is very important, since a mis-diagnosis could possibly be dangerous to a dog's health.
If a veterinarian suspects that a dog is being affected by asthma, it may be necessary to attempt to diagnose the medical condition by attempting to use anti-asthma medications on a dog. If a dog is being affected by asthma, administration of an anti-asthma medication will display noticeable improvements in a dog's asthma symptoms.
If a dog does not respond to anti-asthma medications, however, this is not necessarily cause for a veterinarian to rule out asthma. In some cases, a dog may need to cycle through several anti-asthma medications before displaying visible improvements.