Dozens of dog clinics are opening that are not staffed by licensed vets, warns new research.

An investigation has discovered that many canine fertility clinics are carrying out banned procedures performed by amateurs creating cross-breeds that may not be able to survive, writes Joe Morgan.

The research found at least 37 clinics in operation in the UK which are not run by vets or do not have a vet on site despite that many are offering veterinary services, such as taking bloods and performing Caesarean sections.

Two clinics have advertised canine surgical artificial insemination (AI), a banned procedure.

This increase has happened at the same time as the number of puppies born using artificial insemination has dramatically increased.

Kennel Club figures show there were more AI births in the past three years than there were between 1998 and 2015 - a trend linked to the rise in the popularity of brachycephalic breeds - dogs with short noses and flat faces such as Pugs, Shih Tzus, and Chihuahuas.

Many of the clinics discovered were mobile businesses with rudimentary websites, offering vet services for dogs at cheap prices.

Some of these clinics appeared to advocate 'self-whelping' - whereby the bitch is not taken to the vet in order to give birth, even where this might be advisable - as well as raw feeding.

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Madeleine Campbell, a specialist in animal welfare from the Royal Veterinary College, said: "Artificial insemination is, of itself, ethically permissible in many situations.

"Indeed, it can sometimes have positive welfare effects, for example by removing the need to transport animals over long distances or internationally to breed, or through helping to maintain genetic diversity by facilitating crosses between animals who are geographically remote from each other.

"However, if artificial insemination is being used to achieve pregnancies in animals which for heritable anatomical reasons are not capable of either breeding or giving birth naturally, then that has negative welfare implications and is of ethical concern.

"Furthermore, if the investigations imply that non-vets may be undertaking acts of veterinary surgery such as Caesarean sections, then that is obviously worrying, and would be illegal.

"Concerns about non-vets undertaking acts of veterinary surgery should be reported to trading standards and the police."

The findings were published in the journal Vet Record.