Thavriol stops, maintaining a relaxed posture, though he is poised and ready for action.  He tries to figure out what the growl means or if he recognizes it.

Nature 10

Thavriol's not certain what the growl means though most growls at least carry some implication of warning.

Perigord holds the lantern high and strides into the cave, a treat in the other hand.

"If any can understand me, we're here in peace! ...Free food for the wolves?"

Persuasion: 9

Animal Handling: 7

Beyond the bright light cast from your lantern, you see fur and movement and something moves snarling and gurgling deeper into the cave.

"We are merely here to ascertain your condition. if you are sick, we can try to cure your ailment and discover the cause."

9 animal handling

5 Medicine

11 Nature

15 persuasion

((That at normal speaking volume, or you shouting after the retreating form?))

(normal volume. any louder and we'll scare them.)

Scurrying, then silence greets you.

"Well we found them." Nolla says with a frown at the hill and the cave. She watches two of her companions move up to the cave, but hangs back a bit herself. "What now?" She asks the others.

"Lemme give something a try," Thavriol says. Raising his voice slightly, he says, "Perigord, come on out.  I wanna try somethin'."

Assuming he does, Thavriol moves past him into the cave, taking the food and moving as non-threateningly as possible.  He goes in about 10 feet, being careful where he steps, then he uses his Divine Sense.  Assuming he picks up nothing, he moves in cautiously a little more then says, in Common, Elvish, and Undercommon, "We don't want to fight, but we do need to know what you want and if we can help.  Please talk to us.  We brought you food."  To prove his lack of hostility, the paladin sits down, though he does ready himself to surge to his feet at a moment's notice.

Persuasion 8, if the food gives him advantage, use this roll 15

ooc: Divine Sense As an action, you can detect good and evil. Until the end of your next turn, you can sense anything affected by the hallow spell or know the location of any celestial, fiend, undead within 60 ft. that is not behind total cover. You can use this feature 5 times per long rest.

Perigord backs off a bit and hands off the treat. 

"You can see better than I here, you take point and I'll move back with the lantern. Could be the light that's holding us back here."

((Nothing pops the Divine Sense, what's your Animal Handling, Thav?))

Thavriol Animal Handling 6, if food = Advantage 20

As Thavriol moves into the cave and takes a non-threatening position in the dark, he call out in a calming voice, Peri's treat on the cave floor before him. Eventually he sees a snout poke around the corner and regard him warily. The creature you see in the dark looks to be a wolf, but much of the fur is gone, fallen or singed in splotches, the bare skin looking irritated. 

It gives a faint gurgling whine before stepping forward haltingly. 

((Even with the treat, it won't be willing to come within touching range, so would only approach if you placed the treat outside your reach.))

If so, the wolf limps carefully forward, casting the occasional glance past Thavriol to the others waiting outside the cave, before gingerly extending its head before snapping up the treat with a wet slurp and wheeling back into the cave. There is a pool of viscous, gel-like saliva where the treat once was.

"I hope you be enjoyin' the treat, me friend," Thavriol says in a soothing voice.  "We have move, if you want."  Then he leans over to examine the saliva, being careful not to touch it.

After studying it for a moment, he calls softly, "Nolla, come help me figure this stuff out.  The poor thing is sick.  Come slowly, don't touch your weapons, and crouch.  It's safe."

After she arrives (assuming she does), either Thavriol helps her with a Nature check or will get her help on Medicine  check.

If the latter, here it is Medicine 18

Thavriol looks at it, but it's a bit hard to tell what would be the cause of saliva that viscous. It doesn't seem natural to him, nor the result of any medical condition that comes to mind.

((It is about the consistency of Crystal Gravy.))

Nolla moves into the cave, a bit hesitantly, but soon she is kneeling inside, examining the slobber. "That does not appear something nature-made." She says with a frown. "Hopefully it is not something we can catch, or else we might just have put ourselves in the same boiling pot as those wolves..."

"What could have done this?"

19 investigation

22 nature

((Is Peri the only source of light?))

I believe so, the others have darkvision.