The break-in occurred between 10am on Wednesday, January 3 and 12.15am on Thursday, January 4.
Offenders gained access to the boat, which was moored near Cow Roast marina, between Berkhamsted and Tring, and stole two Chihuahuas from inside.
One of the dogs is black and white with short hair and the other is blonde with long hair.
Detective Constable Chris Phillips, from the Dacorum Local Crime Unit, said: “The owner is extremely upset and is keen to be reunited with the dogs as soon as possible.
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"I would ask anyone who thinks they may have come across these dogs to please contact police. I would also like to hear from anyone who may have witnessed any suspicious activity around the boat between the times stated.”
Anyone with information is asked to contact DC Phillips via on the non-emergency number 101 or email [email protected] quoting crime reference D1/18/108. You can also report information online at https://www.herts.police.uk/Report
Alternatively, you can contact the independent crime-fighting charity Crimestoppers anonymously on 0800 555 111 or through their Anonymous Online Form at www.crimestoppers-uk.org. No personal details are taken, information cannot be traced or recorded and you will never need to go to court.