Cavaliers are not supposed to have curly coats; so consider a straight or slightly wavy coat to be a bonus.
Also coats are very much determined by genes. I have seen small puppies that have far more coat than either of my two boys have ever had. They also have very, very slow growing coats and never went through a big shed of their puppy coat, just a slow and gradual replacement. At over 2 and a half, jaspar still has only just had most of his body turn to adult coat hair and his longer feathering is still puppy coat feathering. People tend to think they've been shorn as their coats are so tight and smooth, but I have never (and would never!
) trim them. By contrast, Lily, who is younger than the boys, is like a mammoth with so much heavy coat that she looks a couple of pounds heavier than she actually is. As her coat is not in the best condition I may have her trimmed just so that the new growth will be healthy. I think her shagginess is partly that she has her puppy coat still, as well. If she blows that coat it will be like a black shag carpet around my home!! :shock:
Ears grow slowly and gradually on all cavaliers.
Black hair tends to be longer and fuller than any other colour and dogs with black tend to have a fuller coat but not always.
A spay or neuter shouldn't affect a dog's coat as much as either genes or being overweight or fed a mediocre diet will. Leo and Jaspar have not gone fluffy or curly as a result of their neuter over a year ago. Lily already has a cottony curly coat and is only being spayed right now (as I type!). She was also very fat, and fed a poor diet, until now. So there's lots of variation. Her coat has improved greatly just from two months of major weight loss, a good diet, regular brushing and fish oils, etc.