Ron Hines DVM PhD 4/29/06

Kennel cough is a stubborn bronchitis that is characterized by a dry harsh cough that occurs with activity or excitement. The bacteria responsible for this condition is usually Bordetella bronchiseptica. Bordetella is a gram-negative bacteria that is often found in the upper airways, nose and throat. It does not always cause disease. It produces kennel cough during periods of stress or when it is combined with other infectious agents such as canine adenovirus, parainfluenza virus or mycoplasma. Bordetella is a tough organism which survives many weeks in a damp environment or water.

Dynamics Of Infection
The normal respiratory tract is lined with fine hairs called cilia which are coated with a thin film of mucous. The cilia undergo constant wave action to carry debris and bacteria out through the mouth. This apparatus is called the mucociliary escalator. The operation of this apparatus can be damaged by the stress of boarding, shipping and crowding as well as dusty or smoky environment and cold temperature. Bordetella is a particularly adept organism in getting around the ciliary/mucous protective barrier and clinging to the lining of the lungs. Aiding in causing the disease is the fact that virus often simultaneously invade the dog.

When dogs develop kennel cough, their owners often tell me that they think something is caught in the dog’s throat. This cough is usually associated with recent time spent at a kennel, dog show or grooming parlor. Transmission is from animal to animal by direct contact or coughed aerosols. Incubation time is 2-8 days. It usually resolves within two weeks with or without treatment. It can be stubborn and persist much longer in toy breeds and dogs with narrowed tracheas (windpipe). Some dogs have a nasal discharge or runny nose.

Recovered dogs can shed the organism for 3-4 months. Bordetella also attacks the respiratory tract of cats, guinea pigs, rabbits, rodents, ferrets and pigs. Although humans are said to be susceptible to bordetella, I have never seen this disease spread to pet owners although the organism of Whooping Cough, Bordetella pertussis is a close relative.

The type and frequency of coughing varies from dog to dog. In a few highly susceptible dogs, bordetella combines with other bacteria to cause bronchopneumonia, which can lead to death.

Diagnosis
Kennel cough can be confused with early distemper, allergies, the collapsing trachea of toy breeds and the migration of hookworms and roundworms through the lungs. We usually diagnose the disease by ruling out these other condition. We also based the diagnosis on its occurrence shortly after exposure to other dogs. Throat swabs from affected dogs do not always grow the organism. X-rays of the lungs of these dogs may show mild signs of pulmonary damage, hyperinflation, collapse of lung air spaces (atelectasis), and consolidation of lobes of the lung.

Treatment
Most cases of kennel cough resolve over two weeks without treatment. In some stressed animals, and young puppies, however, the disease progresses to pneumonia. These dogs need treatment.

Warmth, low stress, good nutrition and antibiotics all speed recovery from severe kennel cough. Two antibiotics that are excellent for treating kennel cough are ammoxicillin/clavulanic acid (Augmentin, Clavamox at 6-12mg/pound twice a day) or trimethoprim/
sulfadiazine or sulfamethoxazole(Bacterim, Septra 15mg/pound once a day). I have treated stubborn cases successfully with Biaxin (clarithromycin 2.5mg/pound twice a day).

Symptomatic relief can be gained by nebulization of compounds that dilate the lungs (ipratropium, Atrovent) and that loosen and break up mucous (guaifenesin and Mucomyst or N-acetylcystine). Three to five milileters of 20% Mucomyst are diluted with an equal volume of water or saline and nebulized three times a day.

Steam showers are also helpful in relieving congestion. Some stubborn cases respond to low doses of corticosteroids such as prednisone (0.12-0 .25mg/pound) twice a day.

Prevention
Two vaccine types are available to prevent kennel cough, injectable and intranasal.
The most effective vaccine is administered intra-nasally. One effective brand is Fort Dodge Bronchi-Shield III which contains, in addition to Bordetella, modified live viruses of the Type 2 Parainfluenza and adenovirus. Intranasal vaccines are quite effective in producing local immunity in the respiratory tract but they may cause a transient cough 3-4 days after vaccination. Puppies can be vaccinated intra-nasally as early as two weeks of age. Revaccination is recommended every 6 months. The vaccine should not be given to pregnant dogs or dogs on antibiotic treatment. The advantage is that immunity is stimulated in the nose and sinuses, right at the site where natural infection would enter.
It takes four days after intranasal vaccination to generate a solid immunity to the disease.

Vaccines that are injected subcutaneously or intramuscularly are somewhat less effective. I use them on occasion on dogs that will not let me approach their muzzle without biting me. It is important that at least two doses be given after the dog is four months of age and annually thereafter. Vaccinated dogs may still develop the disease but it will be less severe.

Although injectable vaccines only contain Bordetella bronchiseptica, yearly vaccinations often contain parainfluenza and Adenovirus type 2 components.
Neither vaccine is effective in dogs that are already incubating the disease or who are exposed to kennel cough organisms before immunity can be stimulated (4-8 days).

Intranasal vaccination may be given as early as 2 weeks of age and immunity generally lasts 10-12 months. (Usually this vaccine is boosted annually.) The advantage here is that the local immunity is stimulated, right at the site where the natural infection would be trying to take hold.
It takes 4 days to generate a solid immune response after intranasal vaccination so it is best if vaccination is given at least 4 days prior to the exposure. Some dogs will have some sneezing or nasal discharge in the week following intranasal vaccination. As a general rule, nasal vaccination provides faster immunity than injectable vaccination.

Adenovirus type 2, Parainfluenza, and canine distemper, can all become members of the “Kennel Cough Complex”. The standard DHLPP vaccine, the basic vaccine for dogs, protects them against these agents.

Terms Of Use

Consult With Dr. Hines

More Articles

Home