Now, a New York-based app is hoping to make matching these animals with potential owners much easier – using a model similar to dating site Tinder.
Animal lovers can browse the profiles of pets, swiping left and right through pictures, save their favourites, and contact the shelters directly.
Called AllPaws, the listings on the free app predominantly come from shelters across the US and Canada, although a number are made by individuals.
There are more than 200,000 pets listed at any one time, and this includes birds, rabbits, cats and dogs, as well as horses, ‘small and furry’ animals, reptiles, and even pigs.
Users browse profiles, or search based on type of animal, breed and shelters within a certain location.
Other filters include the age and size of the pet, whether it’s been vaccinated and neutered, and its compatibility with other animals.
These animals can then be stored as favourites, or shared with other users on Twitter, Facebook and through email.
Once a user finds an animal they’re interested in adopting, they message the shelter directly, for free, through the app to arrange a viewing.
‘AllPaws.com is already responsible for thousands of adoptions, and there is no doubt in our mind that adding an iPhone app for pet adoption will help more pets get adopted’, explained the developers.
‘The AllPaws iPhone app also features the ability to share pets, increasing the likelihood of animals finding a home.’
The free service is only currently available in the US and Canada, and on iOS.
App founder Darrell Lerner told MailOnline that an Android app is in the pipeline, and his team is looking to expand the service outside of the US, but he couldn't provide timings.
'Android is something we'd like to build for as soon as possible given the overwhelming reception the iPhone app has received,' said Mr Lerner.