A New York couple is suing their dog-sitter, claiming she won't give back their champion Samoyed named Polar Mist You Gotta Believe and had the animal neutered, ruining his value.

Cecile and Victor Stanton, of Jericho, N.Y., filed a lawsuit against Beverly Jeffries of Pasadena, Calif., on June 26 in the Superior Court of Los Angeles County, Calif., claiming she refuses to return their dog. In a contract between the two parties signed in February and included in the lawsuit, the Stantons agreed to give temporary physical custody of the AKC-registered Grand Champion to Jeffries while they retained ownership.

The Stantons bought the dog, which answers to the name Justin, in 2006, according to a certificate issued by the American Kennel Club. When the Stantons asked for Justin to be returned in May, Jeffries refused, the suit states.

In their lawsuit the Stantons maintain that Jeffries neutered Justin without their permission in April. The dog, a stud used for breeding, is worth an estimated $250,000, according to the suit.

In the lawsuit the Stantons estimate that they have lost $100,000 in breeding value, now that the dog has been neutered.

The Stantons are suing Jeffries for $350,000, citing breach of contract, promissory fraud, and intentional infliction of severe emotional distress.

It is unclear if Jeffries has an attorney. She could not be reached for comment.

The Stantons and their attorney did not return ABC News' request for comment.