By Dr. Stacy Matthews Branch, DVM
You may hear a whistle-like sound from your dog and think perhaps it is just a snore, but you see that your dog isn’t asleep. Then you realize that the sound is in rhythm with her breathing. This can be a concerning sound, often prompting a visit to the veterinary clinic. This sound is referred to as a wheeze, a high-pitch whistle sound that occurs when breathing in and/or out. Recognizing a wheeze and having a better understanding of the common causes of wheezing can help you to know when to be concerned and what to expect when a veterinary visit is necessary.
What does wheezing sound like?
Wheezing is a high-pitched sound that has a whistle or squeaky quality at the moment of inspiration (breathing in) or expiration (breathing out). The sound is caused by air being forced through airways that have narrowed. It’s often easier to hear wheezing when a dog exhales because the airways tend to narrow more during this phase of breathing. Dog wheezing may occur with other signs of an airway problem, such as at the end of a cough or when sneezing. Some dogs, or even humans, produce wheezing sounds only when snoring. However, when it happens continuously during wakefulness, there is an underlying biological change that may need attention.
Common causes of dog wheezing
Keep in mind that wheezing occurs due to air being forced through a narrower airway. Any part of the airway from the nasal cavity to the lungs can be affected. There are many diverse changes that can cause narrowing of an airway, including inflammation, a foreign body blockage, or spasms in the bronchi. Inflammation is the most common cause seen in dogs visiting veterinary clinics because of wheezing. Common causes of inflammation along the respiratory tract are allergies and asthma. Bronchitis is another common cause of wheezing in dogs and may occur due to both the affects of inflammation (tissue swelling) and spasms that may occur, leading to further narrowing of the bronchial airways. Obstructions such as foreign bodies (e.g. blades of grass) or fluids due to an underlying illness are often associated with wheezing in dogs. Below are some specific causes related to the broad categories described.
Allergies
Many dogs react to allergens (substances responsible for allergic reactions) all year or during certain times of the year. These allergens may be household dust particles, cigarette smoke (1), outdoor irritants such as pollen or insect secretions. While some dogs respond to allergens with skin changes, the respiratory tract is affected in others. When exposed to an allergen affecting a dog’s respiratory tract, they can begin to wheeze. When the airways are exposed to an allergen, they swell or contract as a means to prevent further entry of the substances. In dogs with allergic reactions, these biological responses go too far and result in respiratory signs of distress. If you believe your dogs is experiencing environmental allergies, consider Native Pet’s Allergy Chews, which help target itchy skin and aid in long-term immune support.
Infections
Respiratory infections are notorious for causing noticeable respiratory signs, including wheezing. The upper respiratory disease canine infectious tracheobronchitis, commonly known as kennel cough, is a disease caused by the bacteria Bordetella bronchiseptica. It is very infectious and can quickly spread to other dogs in close contacts, such as in kennels, shelters, and boarding facilities. It is not uncommon for a dog with kennel cough to wheeze along with a honking cough. This condition sometimes resolves without treatment, but it can be approached with the use of effective antibiotics. Fortunately, there is a vaccine to help prevent a dog from contracting kennel cough.
Other species of bacteria such as Streptococcus, Mycoplasma, and Pateurella species can also lead to respiratory infections or lead to more serious conditions of the lungs such as pneumonia. When the lungs are affected, a wheeze can be heard by the veterinarian when listening to the chest with a stethoscope, even if it is not well heard otherwise. Pneumonia is an example of when tiny lung structures called air sacs are obstructed due to fluid or pus accumulation, making it very hard for the animal to get enough oxygen. The dog has labored breathing and may have a wheeze when trying to breathe in enough air. Viral infections can also affect the respiratory tract and lead to wheezing. Canine influenza and parainfluenza viruses are examples, and vaccination against these is available. Dogs can also experience fungal infections of the lungs, but this occurs primarily with dogs who have compromised immune systems.
Parasites
Parasites can also obstruct the airways of dogs and lead to wheezing and other signs such as sneezing, coughing, hacking, and labored breathing. Dogs can become infected with lungworms when coming in contact with contaminated stool or saliva or hosts such as slugs or snails. Wheezing can be a sign in dogs with advanced stages of heartworm disease. Adult heartworms can obstruct blood flow to the lungs leading to wheezing.
Although not commonly seen, infection with a form of nasal mite can also be a source of wheezing in dogs. Nasal mites affect the nasal cavity or sinuses and can cause wheezing, head shaking, and rubbing the face against objects and furniture. An infested dog may also have a significant amount of nasal discharge, nasal bleeding (epistaxis), coughing, and sneezing, including reverse sneezing. Due to the discomfort and pain, an infested dog may stop eating well, then weight loss ensues. When nasal mites are suspected by the veterinarian, the nasal discharge is analyzed, revealing the presence of mites.
Foreign Bodies
Sometimes a piece of a foreign object is the culprit for a dog’s wheezing. There have been cases of a single blade of grass causing a dog to show very concerning respiratory distress. Other times, it’s a piece of food lodged in the trachea (windpipe) after eating too fast or eating non-food items that get stuck in the airway. Foreign bodies obstructing the airway constitute medical emergencies and must be addressed immediately.
Heart Disease
Many pet parents have taken their dogs to the veterinary clinic due to wheezing or other respiratory signs without ever thinking that a heart problem is the cause. Some of these dogs also have heart murmurs. By the time a dog begins wheezing due to an underlying heart issue (such as cardiomyopathy), the heart disease has progressed passed the initial stages. Pet parents can become quite confused if they have a dog with a collapsing trachea and believe that it is the only reason for the wheezing. When the sign gets worse or other signs such as coughing develop, they can be surprised when x-rays show an enlarged heart or lung congestion. When respiratory signs progress, this can signal that clinical diagnostics are needed to determine if heart disease is the cause.
Breed-related breathing difficulty
We have furry friends among us who are born with the burden of a level of labored breathing. Pugs and French Bulldogs are perfect examples. These and other dogs that are brachycephalic (short skull, flat face) can present with brachycephalic obstructive airway syndrome (BOAS) (2). Along with ever-present increased breathing effort, wheezing may be one of the manifestations of this syndrome. The shortened skull and face of dog breeds with BOAS are associated with a longer and thicker soft palate, narrowed nares, and laryngeal collapse, all of which lead to various breathing difficulties, including wheezing.
What to do for your wheezing dog
There are some measures that you can take at home to help alleviate dog wheezing. A good start is to eliminate or reduce exposure to allergens whenever possible. Those who smoke can avoid smoking inside the home or near their dog. Otherwise, it may take some investigative effort to find what your dog is allergic to. Using humidifiers to relieve dry airways or an air purifier to help reduce household allergens may also be a great help. Ensuring that your dog’s immune system is healthy with proper nutrition and immune-supporting supplements can help modulate the body’s immune response to allergens. Keeping up with vaccination schedules and providing heartworm and other parasite preventives are another means to help prevent conditions that can compromise your dog’s respiratory health.
When environmental modifications do not relieve the wheezing, or if other signs develop or progress, a visit to the veterinarian is beneficial so that a diagnosis can be achieved and an appropriate treatment plan can be implemented. In addition to getting historical medical information from you about your dog, the veterinarian will decide the best diagnostic strategy, which may include blood work and x-rays of the chest. Although not listed as a common cause of wheezing, lung cancer can also be ruled out via chest x-rays or ultrasound. An endoscopic exam or microscopic examination of nasal discharge can also help determine if nasal or lung parasites are the source of your dog’s breathing troubles (3). Any videos you can share of the wheezing or other respiratory sounds are very valuable because the sounds often don’t occur while the dog is with the veterinary staff.
The treatment for wheezing depends on the cause(s). Antibiotics for bacterial infections, anti-parasitic agents for lungworms or mites, imiticide treatment protocol to address heartworms, or heart medications for dogs whose respiratory signs are due to heart disease are some of the medical interventions available. In the case of allergies, treatments can take the form of antihistamines, short-term corticosteroids, or other treatments aimed at reducing inflammation of the airways. Providing immune support supplements can also be of benefit as the only intervention or part of a multi-modal treatment approach. Being armed with information to help guide you in recognizing wheezing and understanding the range of causes can help you to get the quickest and best care for you fur baby.
To read more about your dog’s health and wellness needs, visit the Native Pet blog.
References
- Rosati T, Burkitt JM, Watson KD, Jandrey KE, Osborne LG, Sinnott DM, Epstein SE. Obstructive Tracheal Necrosis in a Dog Secondary to Smoke Inhalation Injury-Case Report. Front Vet Sci. 2020 Jul 21;7:409.
- Krainer D, Dupré G. Brachycephalic Obstructive Airway Syndrome. Vet Clin North Am Small Anim Pract. 2022 May;52(3):749-780.
- Loewen JM, Bach JF. Performing an upper airway examination in dogs. J Vet Emerg Crit Care (San Antonio). 2022 Jan;32(S1):16-21.
