I have a grey, tiger-striped tabby, who is now over ten years old. In the last couple years, she has occasionally grown a large clump of fur on her back that solidifies to the point where it needs to be cut off. When this happens, I enlist the help of a groomer to remove it.
I'm curious what causes this clump, and if there's any way for me to prevent it from happening in the future?
These are generally called Mats. They are particularly a problem with long haired cats, but short haired cats can get them too. They are more susceptible to them in the spring and fall when they are shedding their seasonal coats. Also, overweight cats might get them in parts they can't easily reach to groom (i.e. their back).
Prevention is quite simple, just brush your cat regularly and they are unlikely to occur. The main goal is to facilitate shedding. I'd recommend a strong wire brush (often called a cat rake) for this, for example something like:
The reason for this sort of brush is that it gets into their undercoat where mats generally develop. So when brushing your cat with this you want to be fairly aggressive (which they tend to like). The other advantages of regular brushing are that your cat will most likely love it, they will shed less (if your cat is indoors), santization (brushing out dirt / cat litter) and it will help prevent hairballs as well.
As far as what causes them I am not entirely sure, but I think it is probably similar to "Why do cords always end up getting tangled?"
As well as regular brushing which was excellent from Kyle if things are out of control for a start I've also found that very carefully cutting about a quarter of the clump off at a time with a pair of sharp scissors does the trick as well followed by brushing alternating between each over a few days.
It depends on the temperament of the cat and of course make sure not to go too close to the skin with the scissors. Just start a little at a time until they get used to it. Once my partner's cat had a bad case of fur clumps and I thought I'd try moistening with a little water first, but that actually made it harder to remove the main portion so I'd recommend just slowly doing it while the fur is dry.
It is pretty common for cats to get stiff with age. This can make them unable to properly clean hard to reach spots on the back and by the tail. The extra grease and grime acts as a trap to cause the mat.
A way to help clean the cat is to purchase some vet approved cleaning towelettes to get the grease off before it causes another mat.
