While social media may often be more chore than reward for humans, it's changed the lives of thousands of animals.

As the internet has definitively proven, a photo of a kitten or a puppy is irresistible, and animal rescue organisations are using Facebook, Twitter and Instagram to exploit our addiction for good.

According to Claire Garth of the Sydney Dogs and Cats Home, the average time an animal spends in their shelter is currently just 10 days -- something she attributes in part to the centre's use of platforms like Instagram.

"Social media helps to spread the word of animals needing homes, you see a dog you like, you tag a friend, they encourage you to come visit and before you know it we're waving goodbye to another happy adopter," she explained in an email.

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The group Every Greyhound could never have existed without social media, its head Angela Russell pointed out. Launching a Twitter account in 2012, they exist solely to promote greyhounds as family pets and to highlight dogs available for adoption.

Rescue operations are rarely cash-rich. Social media has played a role in getting the message of adoption out minus the steep advertising costs, Garth added.

The Sydney Dogs and Cats Home's Facebook and Instagram accounts give followers a behind the scenes glimpse, encouraging them to donate or volunteer, as well as adopt. It's also been integral for specific campaigns, such as finding the shelter a new location.

"Our community is a huge force in the work we do," she said.

What works best on shelter social media?

Unfortunately, not all animals are equal on social media.

Lisa Wright, general manager of Maggie's Rescue, a rescue operation in Sydney's inner west, told Mashable Australia in an email that images of cats tended to raise less funds than those of dogs.

Telling the animal's story in the right way also matters for the organisation, which has fielded adoption queries through Instagram. "We do find that keeping the message positive as opposed to the sad stories gets pets adopted," she explained.

"Some of our pets with special needs, for example, Kenny, who is a blind dog, is getting attention for how resilient he is and how clever he is adapting to the world."

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Russell agreed. For Every Greyhound, social media is about encouraging people to see the dog as part of their household. "A photo of a dog looking miserable and huddled in a cage doesn’t prompt people to imagine that dog being part of their home and their family and their life," she said.

Ultimately, it's all about the photo and many groups are increasingly focused on capturing an appealing image of their pets.

According to Garth, Facebook is still their most popular account, but Instagram is fast catching up. That might be thanks to their use of professional photography, donated by John Dowling from Sydney Pet Photography, which aims to give each critter 15 minutes of fame.

"The plain white backdrop allows the animal to really steal the spotlight," she added. Some adoptees have even gone on to become their own social media stars, not limited to Albus "Fluffbottom" Greybeard.

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Facebook lets the shelters tell longer stories about their pets' histories, but some feel their posts can get lost thanks to the vagaries of Facebook's timeline algorithm. They can't hire full-time professional social media managers, after all.

"Sometimes I personally pay to promote the page, and we always get a good response to that, but we don't use the charity's money for that," Russell added.

Every Greyhound is also able to have more of a voice on Twitter. "We had a very silly hashtag take off and trend in Eastern Australia over the weekend, #olympicsforgreyhounds, and that just wouldn't work on Facebook," she said.

Getting political about animals

While many adoption organisations are not always outspoken about animal rights issues, some have used their platform to highlight political debates that effect them.

Most recently, the New South Wales government proposed a ban on greyhound racing following a series of news reports detailing allegations of abuse and live baiting. If the legislation successfully passes, it will be organisations like Maggie's Rescue left to deal with re-homing the retired racers.

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While Russell said Every Greyhound doesn't comment on racing, it does sometimes draw attention to the reality of re-homing.

"We definitely shared news of the NSW greyhound ban -- and with many ex-racing greys already in our shelter, it was a great chance to further highlight that these animals can make the most wonderful pets," Garth added.

Wright said the group's social media accounts does have to handle trolls at times, but they are relatively rare. Bad comments and unfair ratings really do matter, she added, as Maggie's Rescue relies on the public to keep afloat.

Apart from blocking the occasional malcontent, being on social media has paid off for the shelter and its creatures.

"It has revolutionised the way we rescue," Wright said. "Dogs and cats in shelters were to a large degree invisible before social media."