Dead cows with their rear legs bound and ear tags removed have been washing ashore in Denmark and Sweden since the New Year.

Yesterday afternoon the third cow washed ashore in Denmark near the town of Skælskør on the island of Zealand.

"Its back legs were tied with nylon string and the stomach was cut open but it looked relatively fresh and the person who reported it said it wasn't there the day before," Niels Johansen from the Slagelse fire and rescue service told TV2 East.

READ MORE: Testicle-chomping fish found in Øresund

Missing ear tags
The other two cows were found on beaches on Lolland and Zealand, while eight have washed ashore on Sweden's south coast according to the tabloid BT.

While some of the cows in Sweden have had their ears removed, the cows in Denmark had their ears intact but no identifying earmarks – removing the earmarks would hide the identity of the cows' owner.

According to BT, Swedish police are treating the incidents as a crime against environment law, but so far no motive has been found.

Pushed overboard
"It's a very strange […] we have never seen anything like this before [and] what we can only imagine is that the animals have fallen in the ocean from a ship," Skåne Police spokesperson Ewa-Gun Westford told Swedish newspaper Sydsvenskan, adding that it was likely that the cows were pushed overboard.

Despite efforts to hide the cows' identity, Swedish police say they have found a piece of ear with a number on it that could make them traceable. According to the Swedish agricultural agency, the ear tags are not the kind used in the EU.

Sydsvenskan reports that Russia – which has a port in the Baltic Sea – imports a large quantity of beef from Brazil, Uruguay, Australia, Paraguay, the US, Mexico and Argentina.