Is my cat's behaviour normal?

Question

Over the past few months, I've been trying to figure out the differences between the two black cats I had for about 5 months. They are about 8 months old and they come from the same litter.

Luna, the much smaller one is a bit quieter than Chilli, the one my inquiry is about. Luna meows when she needs to unlike Chilli, and overall behaves like all of our past cats.

Chilli however, caught my attention through doing things like;

• Rapidly opening her mouth - imagine a dog catching a treat mid-air - only to close it, with no real reason. She does that around 5 times in half an hour, if nothing in the living room happens and every house member is minding their own business.
• When I pet her on the head, she gets so 'excited' that she opens her mouth. Sometimes, she even keeps her mouth open for the next two minutes, even when I had already stopped petting her.
• Unlike Luna, Chilli frequently makes a journey to the kitchen and often gets caught eating some of the leftovers from the plates in the sink. We often eat spaghetti and once Chilli sees that we are finished with the plate, she excitedly jumps up and licks the sauce leftovers until there's none left. (We do not eat Spaghetti with any kind of meat)
• She never rubs herself against any of the house members, or her sister, or the furniture, nor even the walls. Not from what I have seen at least. Luna however does it very often.

Aside from these actions, Chilli behaves just like our past cats. The question is, should I be worried? Or is this normal for her to be like this, considering every cat can be different?

Answer 1

Eating leftovers could be entirely normal. One of my cats likes graham crackers, if she can get them; my previous cat liked broccoli. If she's eating a commercial cat food (and is actually eating a reasonable amount of it), it is unlikely that there's a trace element shortage that she's trying to compensate for, but the way to be sure is to have a vet do tests.

The open mouth is odd, and I do think it calls for a vet visit.

Remember, cats really don't like showing that they are sick or in pain, so "normal behavior otherwise" isn't always good evidence.

Answer 2

Everything seems to be normal even eating left overs.Except opening her mouth.

I had a male cat, Arsalan. He used to eat every thing we ate, e.g. chocolate (later I found out it's not good for them), banana, pomegranate, apple, pasta, noodles, bread (yeast is not good for them), bhajji, kebabs, anything with massala or spicy (giving this rarely is OK but not very often), etc. He disliked plain cooked meat, but he liked it with a bit of salt and more flavour.

But keeping the mouth open is not a good sign. She might have upper respiratory disease, which is very common in cats, It's better to visit the vet. If treated early, it has a lot more chances to be cured. Also, check if it's panting, and drinking more water than usual. Pull her skin from in between her shoulder blade. If it takes longer than usual to reach its original state, she might be dehydrated.