Infectious Tracheobronchitis (Kennel Cough) in Dogs

Overview of Kennel Cough in Dogs

You might think your dog has something stuck in his throat. The cough associated with acute infectious tracheobronchitis, (ITB) or kennel cough, is a high-pitched, honk-like cough, sometimes followed by retching.

Kennel cough is a highly contagious inflammation of the trachea (windpipe) and bronchial tree caused by a contagious virus (adenovirus, parainfluenza virus, canine distemper virus) or bacterium (Bordetella bronchiseptica). The disease is associated most often with dogs housed in a high-density population or boarding kennel. The infectious agents can be transmitted through the air or by contact with contaminated surfaces. Puppies and younger dogs are at greatest risk, but even old dogs can acquire kennel cough.

The incubation period from the time the dog first contracts the infection to the time that symptoms develop is typically between 3 to 10 days, and the symptoms can last for days to weeks. A mild to moderate cough without other symptoms is usually self-limiting; however, occasional cases become lingering and cause chronic bronchitis.

What to Watch For

Kennel cough causes a variety of symptoms that can vary in severity.

• Signs of upper respiratory problems such as conjunctivitis (irritated eyes), rhinitis (runny nose) or sneezing may be observed.
• Cough. The classic symptoms are bouts of a loud, honking cough that worsen with activity or excitement and can persist for minutes. The dog will often act as if something is stuck in the throat and retch or vomit up fluid after coughing. If secondary bacterial pneumonia develops, the dog often shows signs of illness such as loss of appetite, depression, or fever.
• Loss of appetite
• Depression
• Fever
• Difficult breathing

Any of these signs should prompt a visit to see your veterinarian in order to be certain pneumonia has not set in.

Diagnosis of Infectious Tracheobronchitis in Dogs

Complete medical history will usually reveal recent exposure to a kennel or other dogs. Windpipe sensitivity is present in most cases. Diagnostic tests are needed to recognize kennel cough and exclude other diseases. These tests may include:

• A chest X-ray may be recommended to determine if pneumonia is present.
• Routine laboratory blood tests-a complete blood count (CBC) or blood chemistry panel is not necessary unless your pet is showing signs of generalized illness, fever or loss of appetite.
• A fecal flotation should be done to exclude intestinal parasites.
• If signs of eye involvement are observed, the cornea of the eye should be examined carefully.

Treatment of Infectious Tracheobronchitis in Dogs

Therapy is controversial because the disease is usually self-limiting (like a human cold) and, if a viral infection is suspected, antibiotics can’t kill the virus. This is especially true in mild, uncomplicated cases where treatment is supportive-not unlike that given to a person with a bad cold. Treatments for kennel cough may include one or more of the following:

• Cough suppressants are appropriate for some pets with kennel cough. Your veterinarian can discuss the pros and cons of this treatment. Injections or pills (butorphanol) are often used, but occasionally, a stronger medicine is needed (codeine-related) to break the cough cycle. Don’t use over-the-counter human medicine without first speaking to your veterinarian.
• Antibiotics are used in some patients, especially if Bordetella infection or secondary bacterial infection is likely.
• If the symptoms do not improve or should they become chronic, a careful re-evaluation including blood tests and a chest X-ray is indicated.

Home Care

• Deworming of puppies is appropriate if they have not recently received such treatments.
• Limit exercise and enforce periods of rest; don’t exercise or play with your dog. Activity often initiates periods of loud, uncomfortable coughing.
• Encourage adequate fluid intake to maintain hydration. Provide soft food if dry food irritates the throat.
• If your dog normally wears a restraint collar, remove it or replace it with a harness to decrease airway irritation.
• Avoid environmental stresses including house dust, vapors, chemical fumes and tobacco smoke.
• To mobilize secretions and reduce coughing, provide humidified air (e.g. a vaporizer in the dog’s room or in a steamy bathroom for one or two hours).

Preventative Care

Vaccinations provide very good protection against ITB in most dogs. However, like all vaccinations, protection is not 100 percent and some dogs will contract ITB despite vaccination.

In-depth Information Kennel Cough in Dogs

Canine Infectious Tracheobronchitis (ITB), also known as the kennel cough complex, refers to a group of acute contagious infectious respiratory diseases in dogs, which can cause inflammation of the larynx, trachea, bronchi and lung. The condition is especially common in unvaccinated, young dogs.

• Acute tracheobronchitis indicates an inflammatory reaction in the airways. This inflammation usually causes variable increases in tracheobronchial secretions (mucus and “sputum”) and a cough.
• If respiratory clearance mechanisms or immunity are insufficient, pneumonia may develop from the primary infection or from secondary bacterial invaders. Some viruses and bacteria have a predilection for the nasal cavity and membranes of the eye (the conjunctiva), leading to signs of an upper respiratory infection similar to a human cold.
• Common infectious agents responsible for tracheobronchitis in the dog include: Bordetella bronchiseptica (a bacterium); canine parainfluenza virus; canine adenoviruse-2; canine reovirus (a minor cause); and canine herpesvirus (infrequent to rare cause). Bordetella bronchiseptica is the most common bacterial and canine parainfluenza virus is the most common viral isolate noted in dogs with canine infectious tracheobronchitis (ITB).
• Canine distemper virus can mimic these signs and lead to widespread organ disease.

In addition to infectious (contagious) causes of tracheobronchitis, other conditions of the upper and lower airways may cause signs similar to those of infectious tracheobronchial infection. Your veterinarian may need to perform tests to rule out some of these other conditions. This is particularly true if initial treatment of the condition does not lead to an appropriate response. The list of potential causes of these symptoms is very long. They include:

• Pharyngitis (tonsillitis)
• Oral infections with seeding of the tracheobronchial tree
• Laryngeal swelling
• Intestinal parasites (worms)undergoing lung migration
• Fungal infections of the lung
• Pneumonia
• Aspiration pneumonia
• Respiratory tract parasites
• Tracheal collapse
• Allergic bronchitis or chronic bronchitis
• Foreign body inhalation (something really is stuck in the throat)
• Heart disease
• Lung or windpipe tumor or cancer
• Trauma to the trachea (windpipe)

Veterinary care should include diagnostic tests and subsequent treatment recommendations.

In-depth Information on Diagnosis

Diagnostic tests are needed to recognize ITB, and exclude other diseases. Often the diagnosis is made from the history of exposure and the typical clinical signs. If, however, the condition does not improve within 3 to 7 days, additional tests will be needed. If the patient shows “constitutional signs”-such as lethargy, fever, productive cough, cloudy nasal discharge-it is often recommended to obtain basic diagnostic tests to ensure that pneumonia has not developed. Tests may include:

• A complete medical history and physical history.
• A chest X-ray may be requested to screen for infections or anemia.
• Routine laboratory blood tests should be done. A blood chemistry panel is only important if your pet is older, has previously identified diseases or is showing signs of generalized illness, fever or loss of appetite.
• A fecal flotation should be done to exclude intestinal parasites in all puppies unless they have been previously subjected to a regular deworming program.

Additional diagnostic tests may be recommended on an individual pet basis, including:

• If signs of eye involvement are observed, the cornea of the eye should be examined carefully. This should also include tests that can detect a corneal ulcer (especially if the eye seems painful).
• Thoracic X-rays (or repeated films) may be needed to follow the progress of disease.
• A tracheoscopy and bronchoscopy should be done if a foreign body is suspected from history and review of radiographs (x-rays) or if there is a poor response to treatment.
• A culture and cytology of bronchial fluid should be taken. This is especially important if there is a suspicion of a resistant bacteria or a severe pneumonia is present. The procedure is called a “tracheal wash” and can be done under a local anesthetic (placing a needle through the windpipe and flushing in fluid) or by briefly anesthetizing the dog to obtain fluid from the lung. This is then examined under a microscope and cultured for bacteria.
• Fungal tests may be indicated based on results of radiographs in areas endemic for fungal infections such as histoplasmosis and blastomycosis.

In-depth Information on Treatment

Treatments for ITB may include one or more of the following:

• Because antibiotics can’t kill the viruses that are usually responsible for kennel cough, don’t expect your veterinarian to automatically prescribe them. Antibiotics are more likely to be used if Bordetella bacterial infection or secondary bacterial infection is suspected; however, there is no “quick test” for this infection.
• The mild, uncomplicated patient may be given no medication or only a mild cough suppressant.
• Cough suppressants are appropriate when the cough is frequent and debilitating and there is no evidence of pneumonia. An initial injection of butorphanol may help break the cough cycle. Oral administered pills are also available. Stronger medicine codeine-related such as hydrocodone sold as Hycodan or Tussinex) may be needed to break the cough cycle in severe cases. Over-the-counter medicines such as Robitussin should only be used after speaking to your veterinarian.
• In cases of lingering kennel cough, a tracheal washing should be done to culture any offending bacteria. If Bordetella bronchiseptica is found, a powerful antibiotic may be needed (as many routine drugs such as amoxicillin won’t usually kill this bacterium). Some of these can only be given by injection. Some powerful and commonly used oral antibiotics (enrofloxacin (Baytril®) or other fluoroquinolone antibiotics) should not be used in rapidly growing puppies. Occasionally, an antibiotic such as gentamicin may be nebulized (“vaporized”) in the veterinary hospital.
• Very rarely, a brief course of an anti-inflammatory medicine may be needed to quiet a severe cough due to tracheobronchitis; however, these drugs can decrease resistance to secondary bacteria thereby promoting pneumonia.

Follow-up Care for Dogs with Infectious Tracheobronchitis

Optimal treatment for your dog requires a combination of home and professional veterinary care. Follow-up can be critical, especially if your dog does not rapidly improve.

• Administer prescribed veterinary medication as directed and be certain to alert your veterinarian if you are experiencing problems treating your dog.
• Follow up chest X-rays may be required.
• Remember, vaccination can be performed routinely against canine parainfluenza virus, canine adenovirus type 2 and canine distemper virus. Such vaccinations help to prevent infectious tracheobronchitis. A vaccine against Bordetella bronchiseptica may also be administered. This is especially helpful in pets frequently exposed to other dogs.