What is the most likely diagnosis for a puppy presenting with respiratory signs and nodules in the trachea?

The presence of respiratory signs and nodules in the trachea of a puppy suggests a diagnosis of Oslerus osleri infection. Oslerus osleri, also known as the "canine lungworm," is a parasitic infection caused by a nematode that typically infects dogs, particularly younger animals. The infection leads to the formation of nodules in the trachea, which can result in coughing, respiratory distress, and other respiratory signs.

This disease is particularly relevant in puppies as their immune systems are still developing, making them more susceptible to infections. The characteristic tracheal nodules observed in conjunction with respiratory symptoms strongly support the diagnosis of an infection with Oslerus osleri, as this is one of the most recognized presentations of this parasite.

Other potential respiratory issues such as canine distemper, infectious tracheobronchitis (kennel cough), or heartworm disease generally present with different clinical features. Canine distemper may involve gastrointestinal and neurological symptoms alongside respiratory signs, while kennel cough is more likely to cause a cough without the specific nodular lesions in the trachea. Heartworm disease primarily affects older dogs and involves a different set of signs related to heart function rather than nodular growths in