Updated September 25, 2026. Fact-checked against veterinary sources; review by a licensed veterinarian is in progress. See our editorial policy.
Quick answer: Puppies are more vulnerable to respiratory infections because their immune systems are still developing and their vaccine series may not be complete. Kennel cough is common and often mild, but puppies can develop pneumonia quickly, and canine distemper, which starts with respiratory signs, is serious. A puppy with a cough plus lethargy, poor appetite, fever, or breathing changes needs a vet promptly.
Common infections
- Kennel cough complex: Bordetella, parainfluenza, and other viruses
- Canine distemper: eye and nose discharge, cough, fever, and later vomiting, diarrhea, and neurological signs in unvaccinated puppies
- Canine influenza
- Pneumonia, which can develop after other infections
Warning signs
- Lethargy or not eating
- Fever
- Fast or labored breathing
- Thick discharge from eyes or nose
- Vomiting or diarrhea with a cough
- Twitching or seizures
Prevention
- Complete the puppy vaccine series, including distemper
- Ask about Bordetella and influenza vaccines if your puppy will be around other dogs
- Avoid dog parks and unknown dogs until vaccines are complete
- Choose puppy classes that require vaccinations and keep clean facilities
What to avoid
- Human cold medicines
- Waiting when a puppy stops eating
Sources
- Merck Veterinary Manual: Canine infectious respiratory disease complex
- Lappin MR, et al. Antimicrobial use guidelines for treatment of respiratory tract disease in dogs and cats: ISCAID. J Vet Intern Med. 2017
- Merck Veterinary Manual: Canine distemper
- Ellis JA, et al. 2022 AAHA Canine Vaccination Guidelines. J Am Anim Hosp Assoc. 2022
This article is for general education and is not a substitute for care from your own veterinarian. Learn about The Pet Vet and our editorial policy.