There's no vaccine for a cat like Louis, who guards his territory
Louis chases off any cat that visits his garden, but he came off worse recently
Like many cats, Louis is territorial. He sees himself as the king of his local jungle, which in his case means Anne's back garden.
If any other cats dare to come close to the garden, he angrily sees them off, chasing them while yowling loudly.
Anne saw one occasion where another cat was just sitting on the boundary wall of her garden. Louis jumped up and grabbed the other cat by the scruff of the neck.
The two cats tumbled to the ground, then Louis chased the intruder, seeing him off the property.
He's an assertive cat, seeing it as his duty to look after his own patch.
The only cat that he tolerates is a small female, called Kitty, who belongs to an immediate neighbour. Louis has known her since she was a kitten, and he seems to like her, even letting her eat from his food bowl.
In recent weeks, Anne has seen Louis facing up to two other cats: a large black cat and a big ginger one.
The other cats were bigger than Louis, but he stood his ground while they miaowed and hissed loudly at each other.
Eventually, Louis won the staring contest with each of the intruders, and they ran off, with him chasing them.
Last weekend, Anne noticed that Louis wasn't behaving normally.
Normally he spends all day outside, but he started to stay indoors, only going out for a few minutes.
He was nervous when going out of the kitchen door into the garden, looking around cautiously as if afraid of something.
He was behaving differently in other ways too.
He spent most of his time sleeping, which was unlike him.
When he refused to eat his dinner that evening, she knew that there must be something more serious going on.
She picked him up to check him, and he yowled loudly, as if he was sore. Then she found a lump on his chest wall, on the inside of his left front leg, and she realised that he had to go to the vet.
When I examined him, I could tell at once what had happened.
He had a high temperature, indicating that he was dealing with some sort of infection.
And when I looked at the swollen area, I could see that it was painful, red and sore-looking, and a discharge had started to come out of it.
The lump that Anne had found was an abscess which had been caused by a cat bite.
Louis must have come off worst in a fight with one of the bigger cats, being bitten badly on his side.
The area was bruised and reddish-purple, and there was a dirty yellow discharge oozing from it.
I had to give Louis a short anaesthetic so that I could lance the abscess and clean it up.
I flushed it out with mild salty water to remove as much infection as possible.
Louis is on a course of antibiotics and pain relief, and I'll have to check him again in a few days to make sure that he's healing properly.
I'm sure he'll make a good recovery, and there are just two remaining problems.
First, cats that are bitten risk becoming infected with Feline Immunodeficiency Virus, the cat equivalent of HIV.
There's no vaccine against this, and the only way to prevent it is to stop cats from fighting.
Second, Louis is very likely to get into a fight again: there's no cure for cat territorial behaviour.
Anne is just going to have to hope that Louis continues to be top cat, and that the intruder cats keep running away from him.
Louis is a neutered male cat: if he had not been castrated, he would be even more territorial. Neutering cuts cat aggression by over 80pc.
If you have a cat that gets into fights, neutering is the most effective answer. Louis may be a bossy cat, but if he had not been neutered, he'd be far, far worse.
Cat bites are a common injury in territorial cats
Sometimes bites heal naturally but they often need antibiotics
If an abscess forms, surgical drainage is needed