Here’s more on ‘kennel cough’ – the disease that makes pets suffer and the pet parents disturbed. Infectious tracheobronchitis of dogs, in general terms, is referred as ‘kennel cough’. The disease is highly contagious and commonly affects pups and adult dogs, mostly when they come in contact with diseased animals. The dog shelters, boarding kennels, veterinary hospitals and dog shows are the most vulnerable areas wherein the dogs get in close contact with the sufferers leading to spread of the disease. However, it is also possible for dogs to pick up infection from normal, day to day contacts with other dogs such as meeting on the street or in the park.
Canine infectious-tracheobronchitis is usually a mild and self-limiting disease that may occasionally lead to highly fatal bronchopneumonia or chronic bronchitis in young puppies and immunologically compromised adult dogs. The causative pathogens are many which include both viruses and bacteria. However, the main culprits include Bordetella bronchiseptica, a gram-negative rod shaped bacteria and Canine parainfluenza virus belonging to the paramyxoviridae family of RNA viruses. Other viruses that play primary role include Canine adenovirus 2 (CAV2), Canine distemper virus, Canine reovirus and Canine herpes virus to a limited extent. The external factors that make the dogs susceptible to the disease are stress, improper ventilation, extreme temperatures and high humidity.
Disease and symptoms
The delicate hair-like structure in the bronchio-tracheial tract of dogs, termed as cilia, plays major role in removing the irritants from entering the body and causing infection or inflammation. During infection, the invading pathogen damages the cilia and actually causes removal from the tract; thereby, causing loss of natural protective mechanism of dogs for eliminating irritants causing inflammation of upper airways. The susceptible dogs show clinical symptoms after four to six days following the exposure to infection. The typical symptoms include a chronic intermittent, harsh and dry honking cough that resembles to bone-stuck in the throat. Mostly, body temperature and WBC counts remain normal. Sometimes there is a nasal or eye discharge and some dogs, may however show elevated temperature and loss of appetite. The symptoms are aggravated on excitement, or applying gentle pressure at neck region.
The disease is generally diagnosed based on clinical symptoms with a history of recent exposure or contact with infected animals or environment – often during a visit to dog shows, pet clinics or shelters. Isolation of causative pathogen is the confirmatory diagnosis, but generally time consuming and not economical. If it is uncomplicated with other agents, the disease will last around 10 days. However, after the clinical signs subside, the animal will continue to shed the bacteria for 6 to 14 weeks and can therefore still spread the disease to other susceptible animals during this period. Hence, the infected dog needs to be isolated and avoided from mixing with others as the disease is highly contagious and spreads to healthy ones those are not protected.
Appropriate management practices like good nutrition, proper hygienic conditions and nursing care will hasten recovery of the sick animal. To reduce the suffering of animal, cough suppressants containing codeine derivatives are recommended. Corticosteroids might be used in some cases to reduce severity of cough and make dog more comfortable. Antibiotics are generally not required in mild cases, however in more severe cases like running fever, or showing signs of pneumonia, products containing cephalosporins and tetracyclines are preferred. In some non-responders, administration of antibiotics diluted in saline by aerosolisation (applied as aerosols) is preferred, along with bronchodilators for direct action at the tracheobronchial region. However, use of steroids or cough suppressants is not recommended in these cases, in order to avoid the risk of immunosuppression and to clear extra fluid or mucous in pneumonic patients.
Avoiding exposure to infective environment, especially during young age, like dog shows, shelters, and pet clinics will reduce the chance of infection. However, it is not practically feasible to prevent contact with other dogs during the routine walks either in parks or street. Hence, vaccination is the best way of protection from kennel cough. Further, proper immunisation of the pups using either 5-way or 7-way vaccines containing Canine distemper, Canine adeno virus and Canine parainfluenza will provide sufficient immunity against these pathogens causing kennel cough. However, these vaccines do not contain Bordetella bronchiseptica, the major bacterial pathogen responsible for kennel cough. There are vaccines available against Bordetella bronchiseptica, either single or in combination with Canine parainfluenza virus. They are presented as both live and inactivated vaccines and used as injectable or intranasal applications. Use of inactivated vaccines is generally not preferred, as they cannot be applied at a very young age due to interference of maternal antibodies. Further, a booster vaccination is required in such cases for better immunity. These vaccines given by parental route can also cause severe local reactions in some cases. In contrast, modified live vaccines, applied through intranasal route will induce local immunity leading to rapid onset and solid protection within a few days of vaccination. Further, these vaccines can be administered at a very young age as there will be no maternal antibody interference and hence no need for any booster application.
(The authors Dr K Ananda Rao and Col (Dr) Virendra Kumar belong to MSD Animal Health.)