Kennel cough is a common, highly contagious respiratory illness in dogs, leading to public concern about human infection. This concern stems from the fact that the primary bacterial agent responsible for canine infection is capable of infecting humans, although such cases are exceedingly rare. For the vast majority of healthy people, contracting a clinically significant illness from a dog with kennel cough is not a realistic danger. Understanding the causative agent and specific treatment protocols is important for the few who may be at risk.
Understanding Kennel Cough
Kennel cough is the common term for Canine Infectious Respiratory Disease Complex (CIRDC), a highly contagious upper respiratory tract infection in dogs. The most commonly cited bacterial cause is Bordetella bronchiseptica, a bacterium closely related to the one that causes whooping cough in people. Dogs contract the illness by inhaling airborne droplets expelled when an infected animal coughs or sneezes, or by touching contaminated surfaces. The infection causes inflammation in the dog’s trachea and bronchi, leading to the condition’s signature symptom: a harsh, dry, hacking cough that often sounds like the dog has something stuck in its throat. While the infection is usually self-limiting in dogs, it can lead to more severe conditions like pneumonia, particularly in puppies or older dogs.
The Risk of Transmission to Humans
Concern over human infection focuses almost exclusively on the bacterium Bordetella bronchiseptica, as the other viral and bacterial agents involved in CIRDC do not typically infect humans. This bacterium is zoonotic, meaning it can jump from animals to humans, but the frequency of this occurring is extremely uncommon. For healthy individuals, the risk of developing a serious infection from B. bronchiseptica is negligible. Documented human cases almost always involve people whose immune defenses are significantly weakened. High-risk individuals include those with HIV, transplant recipients, or people with chronic lung diseases, who should minimize close contact with sick animals.
Symptoms and Diagnosis
If a human becomes infected with Bordetella bronchiseptica, the clinical presentation often manifests as a respiratory illness. Symptoms can range from a persistent, dry, hacking cough to more concerning signs like fever, difficulty breathing, and pulmonary infiltrates. The infection can progress to bronchitis or pneumonia, especially in patients with compromised immunity or underlying lung disease. Diagnosing this specific infection is challenging because symptoms mimic common respiratory illnesses, such as community-acquired pneumonia or even pertussis (whooping cough). Confirmation requires specific laboratory testing, often involving isolation of the bacterium from respiratory samples like sputum or through bronchoalveolar lavage (BAL). A detailed history of close animal contact is important for guiding the diagnostic process.
Medical Treatment Protocols
Treatment for confirmed Bordetella bronchiseptica infection requires a medical professional and is based on targeted antibiotic therapy and supportive care. Unlike its relative, Bordetella pertussis, which is typically treated with macrolides, B. bronchiseptica often shows resistance to this class. Physicians therefore select different agents, such as tetracyclines (doxycycline) or fluoroquinolones, to effectively eradicate the bacteria. In severe or complicated cases, especially those involving pneumonia or systemic infection, more potent antibiotics like carbapenems may be necessary. The typical course lasts two to four weeks, or longer in immunocompromised patients, alongside supportive measures like rest, adequate hydration, and medications to control excessive coughing.