Please choose the correct ending to complete the given sentence: Pets and Animals: [header] How to diagnose a collapsing trachea in chihuahuas [title] Look for a honking, dry cough. [step] The main sign of a collapsing trachea is a honking, dry type of cough. The cough may sound like a goose honking.

Ending1: [substeps] A chihuahua might cough up black phlegm on his teeth. This might be accompanied by a rattling sound in the throat area. Ending2: This type of cough will make it hard to breathe properly, especially if the dog is having trouble breathing through its mouth. It might also block the lungs for oxygen. Ending3: The cough may be accompanied by other symptoms such as a hearty hacking, and might also be voiced in a hard and grating whisper. [substeps] Your chihuahua may also develop a big " ba-unk " in its throat, which is a kind of meow-like noise that accompanies a dog. Ending4: A coughing episode is most likely to be triggered by pulling on a collar or when the dog pants heavily. [substeps] The cough may happen when you pick up your dog.

Answer format: ending1/ending2/ending3/ending4