Hi, I was wondering if anyone knows what would be safe on a 25 year old cat for fleas. She does have some health issues and is currently under weight. We're working on getting her back up to a healthy weight for eating well. I don't know how much she weighs exactly as my scale's broken. She is hard to hold/ handle at all and can't be bathed. We were using frontline while she was healthier. Now we're worried that the frontline will cause harm to her with her being under weight and in okay but not great health at the time. I also know that fleas won't help her condition which is why I want to get rid of them asap but safely.