Our elderly Chihuahua has been fighting congestive heart failure for 3 years and doing very well. He had blood work a few months ago and everything was good. But recently he has been going down hill. He cant eat out of his bowl, so I hold the food in my hand for him to eat. He sleeps a lot, is wobbley when he walks, of course all signs of his old age etc. BUT we found that on the right side of his neck, there is a "line" of swollen glands or lumph nodes.. and they have atleast doubled in size in the last week. We have decided to put him down, he is also blind and deaf... but my husband wants to know what this may be? thanks