Kit on death's door... e.cuniculi or cocci?

[Naelin]

Hello!
I have a beautiful litter of 8 kits from my best doe, 3 weeks old. All growing fluffy and wonderful, until yesterday we noticed that one looked lethargic and was thin.
We tried getting her under mum, but she has zero appetite.
We feared heat stroke (it was 39°c/102°f outside, but around 29°c/85°f where we were shelving them) and cooled her down with no change. She could walk yesterday but can't today.
After searching any posts here that talk about it I assume it's either e.cuni or cocci, and I will be giving all of the adults some spring onions or garlic, but I have no idea what I can do to prevent it on the other 7 healthy kits, especially not knowing which one it is.

Symptoms:
-No appetite
-Lethargic
-Thin, no bloating.
-Perfectly clean butt, no stuck poop
-Neck and head position is normal
-...Except she often curls up to rest, head pointing to her belly, but upright.
-Stiff back legs and poking front legs to the front, cannot walk. When attempting to walk, her face is on the floor and her back legs are up. Yesterday she was only slightly dragging her back feet.
-Eyes look perfectly normal, no cataracts or white spots.

She's being kept separate from the others now. We know we have cocci going around on the house, but I am not sure if toltrazuril is safe for the nursing does' kits. How could I treat the kits for this and/or e.cuni?

 

[Naelin]

Now she has added some random bursts of noisy breathing, with random cries that sound like a "Weh", kind of like some frog's calls. She doesn't take water fed with a syringe and has trouble keeping her head up.

 

[Alaska Satin]

Now she has added some random bursts of noisy breathing, with random cries that sound like a "Weh", kind of like some frog's calls. She doesn't take water fed with a syringe and has trouble keeping her head up.

That sounds like a dying bunny. I always give any animal that is trying to live a chance to do so, but she sounds like she's given up. If it was me, I would put her down, as I have never had a gasping bunny in those straits recover.

I think you're going to have a hard time figuring this one out. Doesn't sounds like coccidiosis, which always seems to involve some sort of diarrhea or other GI upset. It certainly could be E. cuniculi but the only way to be sure is to do a culture. If the others do not seem to be suffering, it could be a nest box injury, a poor immune system that didn't defend her when the others' did, or just something else wrong with her.

 

[Naelin]

Thanks Alaska!
The kit died shortly after that last message. I wrote this mostly worrying about the rest of the kits assuming some infectious disease.

All of her organs look normal to the best of my knowledge (which is not much) save for a quite pale heart with very dark, blood-shot auricles.
I found one or two pictures of hearts that looked like that, but also one of those were on a website with a report that detailed that as a sign of heart attack.
I also found some blood in the chest cavity, but I am not sure if that happened due to cutting the digestive system away or if she actually had some rupture on an artery.
(ATTACHED BELOW ARE PICTURES OF THE HEART)

EDITED TO ADD: Some folk at the Rabbits Inside Out group figured out she seemed to have GI stasis as well as this hemorrage and said the latter may have been caused by the first. I've stashed some gas drops now.