Species: Dog

Age: 12

Sex/Neuter status: Neutered

Breed: Catahoula X

Body weight: 90lbs (this is on the high end for his main breed, but whatever he is mixed with is bigger, so he's about 5-10 lbs overweight)

History: Ear infections and allergy issues, intolerance to wheat/soy, kennel cough @ 2 years old, recent (Feb.1st) endoscopy to remove sewing needles he ate from the trash. Blood work from endoscopy showed normal thyroid levels and normal blood sugar levels.

Clinical signs: Infrequent hacking cough. Started about two months ago and would notice him hack a few times then make a retching sound (like when he had kennel cough), maybe once a week. No change in eating, pooping, peeing, drinking or energy levels. No phlegm or mucus present. Cough has verrrry slowly increased in frequency since. Within the last two weeks has become more frequent (2-5 times x day), and one cough produced phlegm. Energy level is a bit lower (not dramatically so), eating/drinking/peeing/pooping still normal.

Duration: 2 mos.

Your general location: Seattle, WA

As stated above, my dog had a hacking cough that I would only notice two times a week or so. This started roughly two months ago. Because it was infrequent and he had no mucus/runny nose/phlegm and was otherwise normal I thought it might be allergies (he's never had an allergy that made him cough before, and we've lived in the same region for 11 years). Within the last two weeks its become more frequent. I took him to the vet, where they listened to his heart and lungs and the vet said he has no immediate signs of a heart issue, and that he didn't hear fluid buildup in his lungs. They asked if I wanted to test for kennel cough and I said no, as based on his symptoms and the duration of the cough it didn't seem likely. I check his gums twice a day for dehydration or lack of oxygen and they're always a healthy pink color.

My question is if anybody has any idea why he'd have this long term of a cough and if a chest x-ray would be helpful for diagnosis. I don't live in a region where heart worm is prevalent (we barely get mosquitos, and even then only in July/August), the vets initial once over didn't seem to suggest other heart issues and I'm worried he may have a lung issue (cancer?) not related to an infection.

Thank you.