However, the picture has alarmed animal welfare experts, and not just because of the United top the pooch has been forced into.
The dog, a Can Corso from Russia, has clearly had its ears cropped, according to campaigners, an illegal practice in the UK and Ireland.
Marcus Rashford shared picture of his new dog, Saint, on Instagram on Tuesday morning
Under Section 5 of the Animal Welfare Act 2006, it is illegal to allow a prohibited procedure to be carried out on a protected animal.
However, there are several countries where the process is still legal and there is no wrongdoing in bringing a dog into the country which has been cropped or docked elsewhere.
An RSPCA spokesperson said: ‘The RSPCA is opposed to ear cropping, a process where ears are removed or surgically altered, often for the purposes of appearance.
‘Ear cropping is painful, wholly unnecessary and illegal to carry out in England and Wales. It does not benefit the dog in any way and can be detrimental to their health, behaviour and welfare. We do not believe animals should be mutilated for cosmetic purposes.
Rashford watched from the stands as Manchester United lost to Newcastle on Sunday
Rashford last played for United in the 2-0 win over Huddersfield on February 3
‘Unfortunately, we suspect that ear cropping does take place within England and Wales — although it’s illegal under Section 5 of the Animal Welfare Act 2006 — while some dogs are imported from abroad with cropped ears.
‘We would urge people not to buy a dog with cropped ears as it will have undergone this very painful process.’
Rashford, who sat out United’s 1-0 defeat by Newcastle on Sunday, bought his pup from Chaperone K9, a family run business in Leicestershire that specialise in providing personal and family protection dogs.
Company director Richard Douglas confirmed his company do not crop dogs in the UK, adding: ‘The RSPCA should no better than anyone that there are no companies in the UK that promote or carry out cropping or docking.
‘There are countries where it is still a legal process and dogs can come in from America, and Russia or Hungary. People can buy them in from abroad.’
Saint is the latest dog to join the United family, following the arrivals of Atom and Humber with Alexis Sanchez’s move to Old Trafford.
Rashford has been approached for comment.
Alexis Sanchez’s dogs Atom (R) and Humber (L) are also new members of the United dog clan