Article: Dealing with Kennel Cough

I have had the great joy of having my whole yard come down with kennel cough on two separate occasions. Once about ten years ago, when a customer brought a dog to the yard with this affliction, and a few winters after that when my yard was merged together with another fancier�s dogs. Each instance resulted in two whole yardsful of hacking hounds. What a joy that was! It was as if we were housing a colony of seals. Thus I have had my share of experience with this bugger, and I have also tried various remedies to deal with it. So, what then is �kennel cough?�

Description:
Canine Kennel Cough is a term usually assumed to be a gram-negative bacteria called Bordatella bronchiseptica. The symptoms can range from nothing more than a mild annoyance for a dog ... to something that could ultimately prove to be his demise, should it advance from an upper respiratory ailment into a lower respiratory pneumonia. There is a lot of conflicting information as to �what to do� for kennel cough, treatment-wise, and that is probably because there are actually dozens of different microbes that can potentially cause a �kennel cough,� not just Bordatella bronchiseptica.

Besides Bordatella, among the many other bacteria (as well as viruses) that could potentially cause a kennel cough would be Parainfluenza, Canine Herpes virus, Canine Adenovirus 1 and 2, Streptococcus pnuemonia, Pasteurella multocida, other Streptococci, several Staphylococci, Pseudomonas, Coliform bacteria - and even Mycoplasma infections. What is odd is that normally many of these organisms reside in your dog�s nasal passages, upper trachea, and even in the lungs WITHOUT causing clinical signs.

Infections by these organisms occur when respiratory defense mechanisms are compromised by another infection or some other way in which the dog�s normal defenses become weakened. Such an occurrence, when one assault is made on the system, which triggers another assault, is called a �secondary infection,� and secondary bacterial infections oftentimes complicate the management of primary viral (or other) infections. This is also why sometimes, even when treated with antibiotics, �kennel cough� persists: because the dog is actually being hit on two fronts.

The technical term for �kennel cough� is Tracheobronchitis, which is basically an acute or chronic inflammation of the trachea and bronchial airways; again the condition may be primary or secondary depending on the agent. �Acute� means sudden and severe; �chronic� means longstanding, but (usually) not as severe. Whether acute or chronic, Tracheobronchitis may extend from the bronchioles to the lung parenchyma. The acute form usually hits and then passes. The chronic form can slowly debilitate a dog and eventually lead to pneumonia. It is important, therefore, to make sure a symptomatic dog is treated. Kennel cough can often be triggered in middle-aged and older dogs right after sudden changes in the weather or other environmental stresses.

Symptoms:
Coughing and hacking are the outstanding signs. These are most severe after rest, for instance when a dog wakes up in the morning, or after a change of environment. A hacking cough, and/or mucous discharging from the nostrils, are both tell-tale. At the beginning of exercise you will also see (and hear) these symptoms. Ironically, the respiratory sounds are often essentially normal. In advanced cases, sonorous rales can be heard, and the body temperature will increase. The acute stage of bronchitis passes in 2-3 days; the cough, however, may persist for 2-3 wk. and will usually resolve on its own. Unfortunately, severe bronchitis and pneumonia are difficult to differentiate; the former often extends into the lung parenchyma and results in pneumonia. This is why it is important to act when the first signs become evident.

Diagnosis:
Bronchial washing (tracheal wash) is perhaps the best diagnostic aid to demonstrate which causative agents are causing the condition. Probably the single easiest way to determine if a hacking cough is Bordatella bronchiseptica or not is whether the whole yard gets it or not. Typically if you have Bordatella, your whole yard comes down with it. If that didn't happen, a given dog's cough is likely caused by some other problem/pathogen.

Treatment:
Broad-spectrum antimicrobial therapy is not necessarily needed. While antibiotics may be indicated for treatment of more severe cases, typically persistent, productive coughing is best controlled by expectorants or similar antitussives that contain codeine. If conservative medical management is unsuccessful, radiographs should be taken of the chest and cervical trachea, and a laboratory database evaluated to eliminate other possible problems. I highly recommend a tracheal wash for cytology and culture sensitivity, in any non-responsive case, to identify the exact bacterial cause so as to determine appropriate choice of antibiotics.

For a particularly severe case, placing the dog in a crate in a warm room, and initiating a vaporizer, are ideal to expedite recovery. Adding a ml or two of tea tree oil is extremely therapeutic and can be curative. It is important to continue therapy at least 3 consecutive days beyond apparent cure, as these kinds of pathogens may continue to reside in the respiratory tract though the symptoms have cleared. When stressed, incompletely-treated animals may relapse; they can also act as a source of infection for others. Poor management practices (e.g., overcrowding) are often associated with poor hygienic and environmental conditions, and the resultant stress increases both the incidence and severity of kennel cough. Conditions that favor the spread of infections often occur in kennels, pet shops, boarding facilities, and animal shelters. Because most of us keep our dogs fairly close together, and because we tend to feed them by �walking on down the line� through all of their chain spaces, such a situation is ripe for kennel cough to spread, once any given individual introduces Bordatella to the yard.

Although the majority of kennel cough infections are generally mild, self-limiting outbreaks that don�t require much attention, again it can possibly progress to fatal bronchopneumonia in puppies or to chronic bronchitis in debilitated adult or aged dogs. Bordetella should be suspected whenever the characteristic cough suddenly develops 3-10 days after exposure (average time = 6 days). If other dogs on the yard start coughing within the week of the first individual exhibiting symptoms, you know what you have. Usually severity diminishes during the first 5 days, but the disease can persists for another 10-20 days. (it should be noted that tracheal trauma may produce a similar but generally less severe syndrome. Meaning a dog hitting the end of his chain may �cough� like he has Bordetella, but the way to tell whether or not it's Bordetella or not is whether the other dogs on the yard are symptomatic or not.

A dog may shed the Bordetella organism for 3-4 months after apparent recovery from the disease. Therefore, once you get it on the yard, it is best to immunize the yard on a yearly basis from that point forward, and begin pups as soon as is possible.

Additional Notes on Treatment:
Preferably, affected dogs should NOT be hospitalized because the disease is highly contagious (and also self-limiting). Appropriate management practices, including good nutrition, hygiene, and nursing care, as well as correction of predisposing environmental factors, hasten recovery. Typically, productive coughing should be encouraged, not discouraged. However, in severe cases of non-productive coughing, cough suppressants containing codeine derivatives, such as hydrocodone (0.25 mg/kg body wt, every 6-12 hr, PO) or butorphanol (0.05-0.1 mg/kg, every 6-12 hr, PO or SC).

Antibiotics are usually NOT needed, again except in severe chronic cases. If needed, the antibiotics of choice include cephalosporins, chloramphenicol, and tetracycline. These tend to be preferable because they reach effective concentrations in the tracheobronchial mucosa. Clavamox (12.5-25 mg/kg body weight) by mouth every 12 hours for 14 days is also effective. Trimethoprim-sulphonamide combinations at 15mg/kg body weight by mouth every 12 hours for 14 days have oftentimes worked when nothing else will.

--> Ideally, which antibiotic to use should be selected by culture and sensitivity tests of specimens collected by tracheal wash or bronchoscopy. Antibiotics given PO (by mouth) or IM (intramuscularly) may not significantly reduce the numbers of B. bronchiseptica in the distal trachea or major bronchi.

Thus, in severely affected dogs that are not responsive to parenteral antibiotics, kanamycin sulfate (250 mg) or gentamicin sulfate (50 mg) diluted in 3 mL of saline may be administered by aerosolization b.i.d. for 3 days. Aerosolization treatment should be preceded by administration of bronchodilators. Endotracheal injection of antibiotics (eg, gentamicin) is a possible alternative to aerosolization. Corticosteroids may help alleviate clinical signs but should be used concurrently with an antibacterial agent; cortico-steroids should not be given severely ill, coughing dogs.

Prevention After The Fact:
When the risk of B. bronchiseptica infection is considered to be significant (which is on any yard where there has been an outbreak), it is advisable to vaccinate any new dogs/pups as a routine afterward. When considering choices for vaccination, the use of a live, avirulent, intra-nasal vaccine is preferable to injectible products containing inactivated bacteria or bacterial extracts. A combination of an avirulent B. bronchiseptica and a modified live parainfluenza vaccine is available for intranasal use. One inoculation is administered (intra-nasally) to puppies at 3 wk old, which should be enough to do the trick.

Jack