Now, animals are getting in on the campaign action, with pet owners posting photos of their cats and dogs for or against a Brexit on social media.
The most popular pet-related hashtag, #CatsAgainstBrexit, seemingly began when Scottish academic Lilian Edwards tweeted this cute photo of her cat who is "sad because #Brexit," The Guardian reports.
My cat is sad because #Brexit. If you agree RT w your cat. #CatsAgainstBrexit.
Come on guys, viral time!!! pic.twitter.com/NHH5lBMpZq
- Lilian Edwards (@lilianedwards) June 18, 2016
After Edwards' tweet, other pet owners started posting their own anti-Brexit cat photos and videos:
We're voting in. Are you sure? In. Or out? Definitely in. In, okay. Don't shut the door. #CatsAgainstBrexit #fickle pic.twitter.com/QdrybuHj1q
- GFDavies (@gailfdavies) June 21, 2016
Benni relaxed about foreigners in his garden and thinking diversity should be celebrated #CatsAgainstBrexit pic.twitter.com/O7uZFFyitH
- Jane Thomas (@janekeighley) June 20, 2016
Rocket say this is not a black and white situation and you shouldn't take things lying down #CatsAgainstBrexit pic.twitter.com/sfDyCbosVB
- Tamsin Davies (@DaviesTamsin) June 21, 2016
My cat has just seen the Brexit campaign #CatsAgainstBrexit pic.twitter.com/DGqz2leoBX
- Caylum (@CaylumMatson) June 21, 2016
Mr Fluffles has just heard that if we leave the EU tuna migration might stop.#CatsAgainstBrexit pic.twitter.com/hrC2F3POx3
- Geoff Duke (@GeoffDuke2) June 21, 2016
#CatsAgainstBrexit
Because workers rights are protected by remaining inside the #eu pic.twitter.com/o42kWK9Jmq
- April PrestIN (@OldmoatLibDem) June 20, 2016
Please stay.. #CatsAgainstBrexit pic.twitter.com/OWkEEzQjXu
- Ermintrude (@Ermintrude2) June 21, 2016
Dog owners also joined in the pro-EU fun, using the somewhat less-catchy hashtag #Mutts4Remain.
My sisters dog Maddie gets upset when that ranting Farage is on the tv. #Mutts4Remain #CatsAgainstBrexit pic.twitter.com/ZWyVG5womp
- simon bayley (@simonbayley) June 20, 2016
Disco loves his annual French holiday! Not impressed abt #Brexit. Voting #Mutts4Remain pic.twitter.com/zVEV8deFRX
- Welna B (@anlew) June 21, 2016
#Scotties say #BetterTogether #Mutts4Remain were once expats living in France #petsagainstbrexit pic.twitter.com/ffIXzv7owL
- angela billows (@abillows) June 21, 2016
Some pet owners and parents have tried to start their own variations on the trend with photos of rabbits and even babies who aren't happy about the idea of a Brexit.
@iVoteStay Einar is bored with #Brexit. #CatsAgainstBrexit #Mutts4Remain even #BabiesWantToStay too. pic.twitter.com/30BY7ko2xU
- Anna Barbara Welian (@Ouzaru84) June 21, 2016
Inspired by #CatsAgainstBrexit and #Mutts4Remain, Cornelius has formed #Rabbits4Remain.#StrongerIn #Solidarity pic.twitter.com/8trRMlBTCP
- #VoteRymain! (@Ry1n_B) June 21, 2016
Even leave campaigners, like Tory MEP Daniel Hannan, hopped on the trend to express their opinions:
I asked @RealGrumpyCat what she thought of #CatsAgainstBrexit. She wasn't impressed. pic.twitter.com/Gb4Sj2UGr5
- Daniel Hannan (@DanHannanMEP) June 20, 2016