Gapeworm/Respiratory Infection?

So one of my Cayugas got sick. I kept hearing a strange whistling quack at night but I couldn't figure out who it was until Thursday I went out early and noticed my cayuga girl kind of gasping for air. At first I thought she was trying to lay an egg but actually she was gasping for air. I brought her in the house and started her on antibiotics because I thought she had an upper respiratory infection. After doing some research online I thought perhaps she might has gapeworm, so I started her on ivermectin wormer. I did do a swab of her trachea but found no evidence of worms since she was still wheezing and gasping for air it seemed more like an upper respiratory infection. She also stopped eating and drinking so I had to force feed her water and the antibiotics but I didn't start feeding her food until just yesterday . I was hoping that she would recover and start eating on her own but she's so skinny I didn't want to wait too long. She's been on Amoxicillin antibiotics for 3 days and it seems like she's doing better. She stopped open mouth breathing and gasping for air although she still isn't eating so I have to force feed her. I'm not quite sure how much to feed her so I've been making sure she gets at least one cup of water and half a cup of food a day for now.

Since her breathing is easier my real question is if she has gapeworm do I need to treat the whole duck flock? No one else is showing signs of any breathing issues and while I have one duck that seems a little underweight the rest seem to be normal weight and acting normally. The sick duck is not laying any eggs which is to be expected since she is ill but I believe the majority of the flock is still laying normally. Is gapewrm a contagious worm that all of the ducks will get it or do I just treat them if they come down with symptoms? Is gapeworm a contagious worm that all of the duck will get it or do I just treat them if they come down with something? I keep reading that gapeworm is rare in chickens but there's not much out there on ducks.

Oooh, rough. Glad you are being proactive.

There is a thread, Team Tube Feeding, https://www.backyardchickens.com/t/805728/go-team-tube-feeding/60

Storey's Guide recommends only treating for internal parasites if there is a known infestation.

It also notes that with gapeworm there is often vigorous head-shaking.

Here is my thread on something similar and tube feeding. https://www.backyardchickens.com/t/1011195/fecal-testing

I went ahead and wormed and since safe guard is a really safe wormer I would go ahead and do it if you suspect gape worms. How are you force feeding her? If she isn't eating then I would tube feed since it's easy and much safer than force feeding.

I sorry I should have said tube feeding. I use a syringe and aquarium tubing. By force feeding just meant getting food into her without her consent.

She's had some head shaking but not a lot. She's breathing much better this morning and doesn't sound like Darth Vader anymore. Hopefully she starts eating on her own.

Well my little Cayuga passed away last night. Poor dandelion.

So sad.

So sorry any chance you can get a necropsy done to know exactly what happened?