The RSPCA has said its rehoming centres are at breaking point.
The charity states that this is because the number of animals coming into its care is outpacing the number being adopted.
As a result, the number of animals in private boarding has surged, costing the charity around £500,000 a month.
The RSPCA, which is celebrating its 200th anniversary this year, said that the cost of living crisis has created an "animal welfare crisis".
There are currently more than 1,400 animals in private boarding, including 63 in Devon.
It cost £2.1 million for the charity to care for animals in private boarding in the first quarter of this year.
Almost £1.2 million of this was spent on kennelling dogs.
Karen Colman, head of animal logistics and welfare oversight at the RSPCA, said: "As we celebrate our 200th birthday this year, it’s incredible to see how far animal welfare has come since our founding in 1824.
"But the sad reality is that there’s still so much to do, and we’re currently facing an animal welfare crisis.
"Cruelty is on the rise at a time when our rescue and rehoming centres are at breaking point with the number of animals coming in versus the number being rehomed."
Little Valley Animal Centre in Exeter, run by the RSPCA’s Devon branch, is currently caring for 119 animals and has more waiting to come in.
Dr Samantha Gaines, head of the RSPCA companion animals team, said: "Sadly we’re seeing more animals coming into our care and more pet owners turning to us for help because of the increasing costs of owning a pet, including the cost of food and vet bills.
"The cost of living has also led to a reduction in the number of people who are willing to take on an animal as they try to save money, and a recent RSPCA survey found 72 per cent of people were not planning to get a new pet."
The numbers from the survey were from the national waiting list and didn’t include the individual waiting lists at their local branches.
The RSPCA has a policy of not putting healthy, rehomeable animals to sleep.
Euthanasia is only carried out, on the advice of a vet, to prevent further physical or mental suffering.
The charity makes every effort to find homes for the animals in its care, regardless of the time it takes.
However, this means that animals are staying for longer and spaces are opening up less frequently.
The RSPCA is now appealing to families who feel they can commit to the cost and responsibility of a pet to consider adopting a rescue animal instead of buying from a breeder or pet shop.
Ms Colman said: "We have hundreds of animals in our care with so much love to give, they just need a chance."
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