Almost 30 pairs of green eyes are fixed on me, watching my every move. The stench of cat urine in the kitchen makes my eyes water and my stomach turn. Black cats crawl over the sink, across the cooker, in and out of food cupboards.

But RSPCA inspector Laura Glover, seems unfazed as she chats amicably to the cats' owner. This, she explains later, is all part of the job.

After spending a day with Laura and her colleague, Garry Palmer, I'm left in no doubt about some of the desperate states in which people, and their animals, live. The Stockton house, one of about ten calls we made during the day, was home to almost 100 cats.

The owners had started off with just three cats and let the population increase. After a tip-off, Laura visited the small detached house to find black cats covering almost every square metre, and managed to talk the couple into handing some over to the RSPCA.

"They are in remarkably good condition and well-looked after," she says. "The couple obviously love their cats, but it is physically impossible to look after that many animals."

We lift 20 scratching and spitting cats, some almost wild, into boxes and put them into the animal ambulance which will take them to the RSPCA centre at Great Ayton, near Middlesbrough. The cats are being taken to the centre as and when spaces become available.

Sadly, the North-East has an appalling record when it comes to animal cruelty. Figures released last month showed that more than 6,000 complaints were investigated in Cleveland, Durham and North Yorkshire last year, with 7,000 animal collections. There were around 170 convictions and 330 rescues. The North-East, combined with Yorkshire, consistently tops the animal cruelty league of shame.

But both Garry and Laura say it can be frustrating work trying to get a conviction. "We have to get a vet to stand up in court and say 'this animal has suffered'," says Garry. "That isn't always as easy as it sounds, but I believe the Government is looking at changing some of the legislation, which we would welcome."

The RSPCA wants the Government to introduce a duty of care, which would require animal owners to provide adequate food, water, shelter, veterinary treatment and space.

Every day, thousands of complaints about animal cruelty from members of the public are fielded by a central telephone exchange, and are then passed on to the inspectors. Garry says he can make 15 or 20 house calls in one day.

And the job is not without its dangers. On one visit to a North-East home to investigate a cruelty complaint, the owner pulled out a flick knife and threatened Garry and Laura. Garry managed to wrestle the knife from him.

Laura says: "It is unusual for it to happen, but sometimes people are so angry they just flip. They are usually more bothered about the fact that somebody has reported them to us, and they want to know who it is."

We visit a Darlington house where the RSPCA have received reports of a neglected dog. The owner is not in, but a neighbour, who wants to remain anonymous, tells Garry he has heard the dog in distress, as if it is being kicked or punched. Garry will make regular checks on the animal to monitor the problem.

Later, Laura is called to a visiting circus, where a member of the public has complained that an elephant has an injured ear. Laura admits she is not in favour of circuses, but her job demands she goes in with an open mind.

The circus owner is friendly, and is keen to show us all of his animals. An Indian elephant, now retired, is in a part of the field surrounded by an electric fence. We approach it cautiously, and Laura just has time to check its ear, which turns out to be slightly withered with age rather than any injury, before the elephant starts moving along the field again. Laura's nerve gives way and she makes a quick exit.

The circus owner is keen to show us his horses, mainly stallions, who appear to be well looked after. In almost every town he visits, he faces protests from animal rights campaigners, but the RSPCA has no complaints today about his animals being mistreated.

Afterwards, Laura admits she was a little wary of the elephant. "I don't have phobias, but large animals make me nervous," she says. "But it's all part of the job and you get used to it."

Also part of the job is checking that animals are not living in squalor. "Some animals, in particular cats, are very clean animals and it distresses them if they are living in dirty conditions," says Laura. In some homes the inspectors visit, animals wallow in their own faeces.

Laura says one of the most distressing cases was where a woman had left her dog to starve to death in her kitchen. "She just left it there to die, without food or water," she says. "There was evidence that she had visited the animal a few days before it died, so she must have known what sort of a state it was in. I found that really shocking."

Other calls that day include a visit to a home owner in the Darlington area. Garry and a local policeman had asked the man to clear up his house, and to prevent vermin, because it was too squalid for his three cats.

The house is stuffy and unventilated. Cat fur seems to lodge itself in the back of my throat and I start to wonder when the owner last opened his windows. There is rubbish strewn across the floor. Strangely, Garry and the policeman are delighted, and congratulate the owner on his mammoth clean-up.

"If you thought that was bad, you should have seen it before he cleared up," Garry says to me afterwards. "You would be amazed it's as tidy as it is."

One shocking case the inspectors dealt with earlier this year was that of a dog named Ben who was one of four emaciated dogs found living in filth in the kitchen of a house in Hartlepool. Thanks to the RSPCA inspectors, he was rescued and now lives with a family in Durham.

"It's a worthwhile job when we can see happy endings," says Laura. "There's a temptation to adopt every animal you rescue, but you have to be careful. One RSPCA inspector in another part of the country adopted so many pets she was sacked because she wasn't looking after them all properly.

"It can be heartbreaking seeing animals in distress, but apart from that it is the best job you could wish for."