A guide dog has been left “nervous about going out” after it was attacked by a smaller dog while on a walk with its owner.

Hertfordshire Constabulary is investigating the incident, which occurred in Cassiobury Park between 6.30am and 7am on Monday, December 7.

The victim, who is blind, was walking his two Labrador Retrievers in the park when they were attacked by a smaller dog.

One of the dogs is a guide dog, the force said.

The victim’s dogs were uninjured, but he says it caused the guide dog to be "nervous about going out".

This has in turn has made it difficult for him to get around since the incident, police say.

Officers are now appealing for information following the attack.

PC Maisie Shadbolt, who is investigating, said: “We know some time has passed since the incident but we have made a number of enquiries since it occurred, and we now have reason to believe the small dog was possibly a grey-coloured terrier type called Stanley.

“I am appealing to those who regularly walk their dogs in Cassiobury Park to think about whether they know a dog matching this description and if so, to contact me as soon as possible.

“We are also still keen to speak to anyone who was in the park at the time of the incident and witnessed the attack, or remembers anything else of significance.”

Information can be reported by calling 101 quoting reference 41/102290/20.