Long-term Gasping, no other symptoms

[Rhiannon_In_Nature]

My mother has a chicken that has had issues with gasping for about a year now. The chicken is four years old I think this year. Last year we believe she got stung by a wasp she ate, because she suddenly started breathing with her mouth open and occasionally shaking her head and making a high-pitched squawk. The hen did slow a bit eating as well. Mom checked her over and there was no rattling, wheezing, or discharge. We suspect wasp sting because there was a nest close to her run and it happened so suddenly. I cannot remember if my mother observed any swelling in the chicken's neck at the time it began. Her poop was normal, crop felt normal, and she continued to lay eggs.

Over a few weeks the gasping improved and her eating returned to normal. Since then, the hen acts normally unless she is stressed, it is warm out, or she eats a piece of grass. Then she starts gasping almost every breath, shakes her head, and occasionally does the high-pitched squawk. We have never been able to see anything in her throat and I do not feel anything unusual in her neck. More recently, she had not started laying yet this spring, but today I found two eggs which I float tested and were good, so likely laid recently. Still no wheezing, rattling, whistling, or discharge.

With how long this has been going on, we are fairly certain it isn't gapeworm or an infectious disease. After a year we assume either of those would have killed her by now. This hen lives on her own, but within sight of a small flock, and none of the hens in that flock show the same symptoms. Our best guess is maybe she has scar tissue from the sting. Has anyone seen anything like this? Any thoughts on the cause? I have added two videos to show what the hen does.

 

[TSA]

What all do you feed her?

 

[Rhiannon_In_Nature]

She eats Purina Layena Pellets, cracked corn, and dried mealworms as a treat. She also gets a small amount of fruit and veggie table scraps. I think it would be interesting to reduce the food particle size to see if that may be aggravating the problem.

 

[Rhiannon_In_Nature]

Let hen out this evening now that it isn't as hot, and no gasping at all, just quietly pecked around and followed me. So heat definitely contributes, though I don't think it's the only trigger.

 

[Wyorp Rock]

Since then, the hen acts normally unless she is stressed, it is warm out, or she eats a piece of grass. Then she starts gasping almost every breath, shakes her head, and occasionally does the high-pitched squawk.

The high pitched squawk is a cough like she trying to clear something.
Interesting she is fine unless stressed, hot or eats grass. It could be that she is having a relapse of respiratory infection, but it would be hard to know.

Since eating grass triggers it, I would eliminate access to grass. Being hot, well that's harder control, but a fan to help circulate air may help with that. Stress can be from many things, but if you can reduce that see if that helps too.

Lastly, offer her a wet mash of feed, eliminate the scratch and give a little egg, fish or meat as a treat - something "softer" - see if any of these things makes a difference. Check her crop first thing to see if it's emptying overnight as well.