Dog Asthma (Allergic Bronchitis)

Introduction

Asthma is a condition marked by recurrent attacks of difficulty breathing (dyspnea). Asthmatic dogs typically display wheezing and shortness of breath. They also have spasms and constriction of the large upper airways. In dogs, asthma is usually referred to as allergic bronchitis. It is a rather common condition in our domestic dogs.

Causes & Prevention

Causes of Asthma (Allergic Bronchitis)in Dogs
Asthma in dogs is typically caused by an allergic reaction to something in the environment – called an allergen – which is usually, but not always, inhaled. The allergen itself can be virtually anything. Common inciting causes of canine allergic bronchitis include chemicals, cigarette or fireplace smoke, air pollution (smog, smoke from wildfires or crop burning), carpet cleaners or other household cleaning products, perfumes (including those in deodorant or hair spray), room fresheners, fertilizers, home remodeling products, paint, landscaping materials, pesticides, pollen, grasses, weeds or other shrubbery and animal dander (new pets, kennel or veterinary visits), among other things. Often, the precise asthmatic trigger is never identified.

Preventing Asthma (Allergic Bronchitis) in Dogs
Canine allergic bronchitis can only be prevented by identifying and removing the inciting allergens from the dog's environment, or by otherwise preventing contact by the dog with those allergens. If that cannot be accomplished, certain medications are available to help manage the symptoms of asthma, although medication will not actually "prevent" the condition.

Special Notes
Fortunately, allergic bronchitis in dogs is uncommon. Because the signs of asthma mimic those associated with other conditions, such as heartworm disease and other lung infections or disorders, diagnosis of asthma is only made after extensive assessment to rule out other potential causes of the clinical signs. The prognosis for dogs with asthma is good to excellent if the inciting allergen can be identified and avoided. Long-term symptomatic treatment will be necessary in most other cases to enable affected dogs to lead relatively normal lives. If the condition becomes chronic, it will be progressive but rarely life-threatening and, with consistent medical management, those dogs should also enjoy a very good quality of life, with a normal life expectancy.

Symptoms & Signs

Introduction
Asthma is basically a term for difficulty breathing (called "dyspnea"). It usually includes wheezing and shortness of breath due to spasms and constriction of the large upper airways (the trachea and bronchi). Dogs, like people, can develop asthma, although in dogs the disorder typically is referred to as allergic bronchitis. In dogs, this condition is almost always caused by an allergic reaction to something in the environment, which in turn causes an inflammatory response in the upper airways. Most of the time, the allergen is something that the dog inhales. Long-standing allergic bronchitis can damage the tissues lining the respiratory tract, causing the more permanent changes associated with chronic bronchitis. The symptoms of so-called "asthma attacks" can vary widely from occasional breathing problems to severe dyspnea that approaches suffocation. By the time the condition is this severe, it usually has become chronic and irreversible. In very grave cases, the dog may resort to open-mouth breathing, and its gums and other mucous membranes may turn a purplish-blue from oxygen deprivation. When the consequences of asthma become this severe, the dog needs immediate emergency veterinary care to survive.

Symptoms of Allergic Bronchitis in Dogs
Canine allergic bronchitis tends to affect young to middle-aged dogs, although older animals occasionally are affected as well. The hallmark of allergic bronchitis is a chronic, dry hacking cough, which can come on slowly or suddenly. Other common signs include:

Respiratory distress (difficulty breathing, shortness of breath, wheezing, dyspnea)
Open-mouth breathing
Cough (dry, hacking)
Pale mucous membranes (blue-ish gums)
Lethargy
Exercise intolerance
Lack of appetite
Weight loss
Asthma is much less common in dogs than in cats; feline asthma is a well-documented disorder. The observable signs of asthma in dogs can range from mild to severe. Often, the exact asthmatic trigger is never identified. Some dogs become lethargic, stop eating and lose weight due to the discomfort caused by the condition. By the time this happens, the condition usually has progressed to chronic bronchitis, which is progressive and irreversible. In very severe cases, a dog may resort to open-mouth breathing and its gums and other mucus membranes may turn a purplish-blue from oxygen deprivation. When the consequences of allergic bronchitis become this severe, the dog needs immediate emergency veterinary care. Fortunately, allergic bronchitis in dogs is uncommon and normally can be effectively treated with medication. If your dog show signs of difficulty breathing accompanied by a dry, raspy cough, take him to your veterinarian as soon as possible.

Dogs At Increased Risk
Chronic allergic bronchitis, or asthma, is most common in older, small breed dogs of either gender, although large breed dogs should not be overlooked. Dogs exposed to particular environmental allergens are at an increased risk of developing this disorder; those allergens include cigarette or cigar smoke, wood burning stoves, fireplaces, carpet or floor cleaners and deodorizers and air fresheners.

Diagnosis & Tests

Introduction
The signs of allergic bronchitis, which typically include a dry, hacking cough, wheezing and shortness of breath, can be very frightening for dog owners and for their dogs. Fortunately, veterinarians have a number of tools to help diagnose this condition so that effective treatment can begin.

How Allergic Bronchitis in Dogs is Diagnosed
There is no single test that will conclusively confirm whether a dog has allergic bronchitis or some other type of respiratory disorder. A diagnosis of canine "asthma" is made based upon a number of things, including the dog's presenting clinical signs, a thorough physical examination and history and ruling out other conditions that could cause or contribute to the symptoms. It can greatly help your veterinarian if you write down all the signs you notice in your dog and bring that list with you to your dog's appointment. Include exactly what you notice about your dog that you think is abnormal, such as coughing, choking, gasping, wheezing, or whatever. Also document what it sounded like (dry cough, wet cough, wheezing, etc.), the frequency of the signs, how long they lasted and anything else you can recall about your dog's abnormal behavior that caused you concern.

After discussing these signs, your veterinarian will perform a physical examination – including careful auscultation of your dog's lungs using a stethoscope - and probably will take radiographs (x-rays) of your dog's chest as well. With bronchitis, the chest films may show evidence of inflammatory lung damage, infection or scarring of lung tissue, or they may appear normal. Other tests that may help eliminate or confirm causes of acute or chronic coughing include transtracheal wash, bronchoalveolar lavage, bronchoscopy with specimen collection, heartworm and fecal tests for internal parasites, echocardiography to assess the heart and comprehensive blood and urine evaluation to assess systemic health and organ function. Sometimes, a positive response to medical treatment helps confirm a diagnosis of canine allergic bronchitis when other tests prove unhelpful. Fortunately, most dogs with this condition can be treated successfully.

Special Notes
Canine asthma, or allergic bronchitis, is not easy to diagnose. However, there are a number of medications that your veterinarian can discuss with you that can be quite effective in managing this condition.

Treatment Options

Introduction
Although canine allergic bronchitis (also called "asthma") is uncommon in dogs, when it does happen it can be quite distressing to owners and to the affected animal. Fortunately, a number of treatment options are available to help manage and minimize the consequences of this disorder. The goals of treating allergic bronchitis are to identify and remove the inciting allergens from the dog's environment if at all possible; they are usually something that the dog has inhaled. If that cannot be accomplished, a number of different medications are available to treat the condition symptomatically. Once the disorder becomes chronic, complete resolution of the cough is almost never possible. In those cases, the therapeutic goal becomes reduction of the frequency and severity of the cough so that the dog is more comfortable.

Treatment Options
Once allergic bronchitis is suspected, the treating veterinarian will try to identify the underlying cause of the allergy attack so that it can be removed from the dog's environment. Owners may be asked to keep an "allergy diary," which records when a dog has an asthmatic attack, the severity of the attack, how long the attack lasted and what potential inhaled allergens the dog was exposed to at that time. The dog's doctor may carefully question the owner about any possibly relevant changes in the household environment, such as use of new kitty litter, cigarette or fireplace smoke, carpet cleaners or other household items containing perfumes such as deodorant or hair spray, room fresheners, fertilizers, home remodeling products, painting, landscaping, pesticide use, new pets and similar items. Unfortunately, even a detailed owner diary and a thorough veterinary interview may not reveal the precise allergen(s) involved. If it does, the owner can take steps to remove those allergens from their dog's immediate environment.

Dogs with allergic bronchitis should be treated aggressively in order to minimize long-term airway inflammation and resulting chronic bronchial damage. The most common treatment protocol is administration of glucocorticoids and bronchodilators to help reduce the number and severity of allergic attacks. Metered-dose inhalers designed to fit a dog's muzzle are increasingly available to administer bronchodilators and anti-inflammatory medication. In cases of secondary infection, antibiotics that penetrate airway secretions may be recommended as well; incorporation of antibiotic therapy should follow evaluation and culture of airway samples. Finally, cough suppressants are available for prolonged or exhausting non-productive coughs, although they are used cautiously because coughs are a useful and normal mechanism for clearing airway secretions.

Prognosis
The prognosis for dogs with allergic bronchitis is good to excellent with prompt diagnosis and treatment – especially if the inciting inhaled allergen can be identified and removed from the dog's environment. Long-term treatment will be necessary in most other cases to control clinical signs and permit affected dogs to lead relatively normal, high-quality lives. If the condition becomes chronic, it will be progressive but rarely life-threatening and, with medical management and attentive owners, those dogs too should enjoy an excellent quality of life with a normal life expectancy.