French police are hunting the perpetrators of a series of savage animal mutilations across the country in recent weeks.

Investigators have advised the owners of horses and donkeys to be particularly vigilant after more than a dozen attacks left animals dead or severely injured.

Officers say they are mystified by the motives for the mutilations and are looking into whether they are linked to satanic rituals or an online challenge.

In one recent incident, the owner of an animal refuge in Burgundy was taken to hospital with a knife wound after confronting two men who had broken into the property and slashed two ponies and a horse.

In many attacks the animals are found with ears, eyes, muzzles or other body parts removed or with severe injuries to their genitals.

The Ranch de L’Espoir (Ranch of Hope), a refuge for about 100 abandoned, mistreated and rescued animals in the Burgundy village of Villefranche-Saint-Phal, was broken into on Monday at about midnight.

Nicolas Demajean, the ranch’s president, said he was woken by the panicked squealing of two pigs. He got up and confronted one of the intruders with his walking stick, and was slashed along his left forearm with a knife.

“I didn’t think about being afraid at the time, I was just worried about the animals, but I’m on edge now,” he said. “I set one of our dogs on them but they ran off. We found they’d cut two of the ponies and a horse. One of the ponies had several knife cuts, one of them 50cm long on the right side. The other was less seriously cut but is extremely traumatised.”

Demajean added: “I don’t know why, but they came here to kill, that’s for sure. It seems to be some kind of ritual. This is a really quiet village. We never for one minute imagined it would happen here.”

The refuge relies mostly on public donations and paying visitors, and its income has been hit by the coronavirus lockdown. “Now we have to find the money to pay the vet’s bills and try to install better security and cameras to protect the animals,” Demajean said.

Since the beginning of the year at least 15 similar attacks have been reported across France. Police are struggling to connect the incidents.

In one case this month, an 18-month-old foal was found dead in its enclosure at a riding school in eastern France. It had been stabbed in the heart and body parts had been removed.

In another incident, a horse was stunned and had its eye gouged out and a piece of leg bone removed. The animal later died.

A national police spokesperson said: “We don’t understand what is behind this. Is it a satanic right, some macabre trophy hunt or an internet challenge? We just don’t know. It’s very traumatising.”

A Paris police spokesperson said there were similar attacks in France, Belgium and Germany between 2014 and 2016.

British police reported cases of what became known as “horse ripping” in the early 2000s.