West Cornwall Police are investigating what they describe as a "worrying" increase in criminal damage to farms across the region.
Attacks started in 2008 and over recent weeks have increased "dramatically".
They usually involve the sawing of panels or dismantling and removing gates and fences, and cutting or creating holes in the water troughs, the police said.
As a result of these crimes, cattle and ponies have been either left without a water supply or are escaping onto roads.
Grazing on the moorland has been ongoing for many years and some of the fences and gates that have been damaged have been in place for 15 to 20 years.
Sergeant Cara Trott, neighbourhood team leader for the area said: "Police are investigating these incidents and anyone caught will be prosecuted for criminal damage.
"Whatever the motive, these incidents are criminal and are also extremely dangerous.
"Cattle and ponies getting onto the winding roads where people are not expecting them could result in someone getting killed.
"One of these farms has been attacked at least fifteen times since September alone.
"I would urge anyone carrying out these offences to stop before someone is seriously injured. We will do everything we can to find out who is responsible so that these farming families can live without the fear of continually being victimised."
Anyone who has any information or has witnessed any of these incidents, can contact Devon and Cornwall Police on the non-emergency number 101 or Crimestoppers anonymously on 0800 555111 quoting crime reference AP/13/56
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article