Dog walkers have been warned to be cautious as an extremely toxic substance has been discovered on a field.

Several cattle boluses have been found on Hyde Hill, between Bothenhampton and Walditch, and contain a substance called Monensin which can be extremely toxic, if eaten, to dogs and horses.

In November, a dog died after eating parts of discarded cattle bolus in the same area, when several of the items - used to control metabolic disease in some cattle - were found hidden in grass.

A dog walker, who wished to remain anonymous, claims to have found several more in the past few weeks.

The dog walker said: “Within a five-minute period, and in one single field, I picked up around seven boluses - some intact and some ruptured. All were very close to a footpath popular with walkers. Dogs could easily pick them up in their mouths. Small children could also gather them up and involuntarily ingest the toxin from their fingers. We regularly walked on these hills with our children and the boluses could be mistaken for plastic toys. I feel certain that our son would have picked them up as a young child.

“Given that one dog has already died as a result of these boluses, I find it hard to believe that they are still so prolific in an area frequented by dog walkers and the general public. There are no warning signs and therefore no indication that toxins are present.”

The walker reported the incident to police and West Dorset District Council’s environmental health department, both of which are working with the land owner to solve the issue.

Cllr Alan Thacker, WDDC spokesman for community safety and access, said: “We are aware of the cattle boluses found in the field.

“The land owner has permission from the Environment Agency to spread abattoir waste over their land which may have caused the distribution of boluses.

“We are working with the land owner, Environment Agency and other partners to ensure these are removed and disposed of in the correct manner.

“We recommend dog walkers avoid this field or walk their dog on a lead until the boluses are cleared.”

Dorset Police confirmed they received a report shortly before 6pm on Tuesday, April 3 from a member of the public in Bothenhampton on the discovery of seven cattle boluses containing potentially toxic substances.

The matter was referred to the fire service so its hazardous materials experts could deal with the incident and give appropriate advice. There was no further police involvement.