Kennel cough

Definition

Kennel cough is a dry hacking cough in canines, analogous with a chest cold in humans. Dog owners often describe the cough as sounding like the dog is trying to remove something stuck in its throat. It is usually not a dangerous condition except under special circumstances. The cough is caused by the respiratory lining becoming inflamed by infection. With removal of the infection, the lining rapidly heals and the cough is eliminated.

Dogs infected with kennel cough may have it activated by exercise or abnormal activity. Some dogs may cough every few minutes all day long.

How infection occurs

Dogs are similar to humans in that the respiratory system has built in protective mechanisms. In dogs, tiny cilia line the respiratory system which coupled with mucous trap irritants including environmental pollutants and infectious agents. Usually the trapped materials are transported upward toward the mouth where it can be expelled or swallowed. The mechanism for this process is called the mucociliary escalator. The system can be compromised by exposure to certain conditions such as

• crowded conditions
• shipping stress
• exposure to dust
• exposure to cigarette smoke
• infectious agents
• cold temperatures along with the concomitant low humidity
• poor ventilation

When this escalator is compromised it becomes a relatively simple matter for invaders to take advantage of the situation. Chief among these are the bacteria Bordatella bronchiseptica. Bordatella have the ability to bind directly to the cilia and render them inoperative for up to 3 hours. Bordatella also secretes a substance which disables the immune cells which are normally responsible for attacking and destroying invading bacteria.

Bordatella is not usually the sole culprit in cases of kennel cough, but are found with at least one of the following:

• reovirus
• adenovirus
• parainfluenza virus
• distemper virus

The combination of Bordatella with the above infective agents make kennel cough a complex of various illnesses instead of an illness by a single organism.

Dogs get infected when they are in an environment with many other dogs, the area has poor circulation, and high humidity. The concentration of dogs raises the chance of there being an infected animal. The infected animal expels the bacteria with its respiration. Poor circulation allows for concentrations of infective bodies in the air supply, and high humidity fosters the reproduction of infectious agents. Most dogs who exhibit the hacking cough after being in close proximity with other dogs at a boarding kennel, grooming parlor, veterinary clinic or hospital, dog show, obedience class, or park are usually infected with some form of kennel cough.

Incubation period

Bordatella is present not just in dogs, but is also found in guinea pigs, rabbits, pigs, and cats. It is not contagious to humans though it is related to Bordatella pertussis, the bacterial agent responsible for Whooping Cough in humans. Bordatella is a moderately infective agent, depending on stress levels, exposure to other pathogenic agents, and vaccination levels.

The incubation period is from 2-14 days after exposure.

Treatment

Treatment can be through administration of antibiotics to kill the infective agent, use of cough suppressants to alleviate cough and promote natural healing of damaged airways, or a combination of both.

Doctor, is it serious?

Young puppies, especially ones stressed by shipping conditions, are prime subjects for severe cases of kennel cough, which may progress into pneumonia if untreated. Other severe cases which involve infection with distemper also are prone to severe complications if left untreated.

Vaccination

There are two methods of vaccination available. Injection via hypodermic may be safer in aggressive dogs who may bite if their face area is approached. This method offers protection when 2 vaccinations are administered after 4 months of age, with an annual booster required. Protection may not keep dogs from becoming infected, but does restrict severity of symptoms. The second method is via intranasal drops. Dogs can be treated as young as 2 weeks of age. Drops are placed in the dogs nasal passages which are then aspirated into the nasal complex. This method stimulates local immunity in the area where infection usually occurs. Dogs may experience nasal discharge and sneezing as side effects of this method. Nasal vaccination provides faster immunity than hypodermic vaccination. Usually it takes 4 days after intranasal vaccination for full immunity to develop. Plan on administering any vaccination long enough before potential exposure for the animal to develop immunity.

Additional information

In dogs who already are infected with kennel cough, vacinnation has no value. Kennel cough is usually a condition which will run its course and is then overcome by the dog's own immune system. Vaccination is useful as a preventive measure, helping the animal to fend off the infection before it finds a foothold.

Sources:
http://www.marvistavet.com/html/body_kennel_cough.html
http://www.thepetcenter.com/gen/kenc.html