The Prince George's County police department's canine unit is enforcing a decades-old policy requiring squad members to build four-foot-high fences around the kennels of police dogs kept at their homes. If they don't, the officers could face expulsion from the canine squad--and the police union is challenging the policy.

The police union president said that under the union's contract with the department, the police department is responsible for providing equipment for officers in specialized units--including the fence.

In recent weeks, officials in the special operations division--which the 23-officer canine unit is part of--inspected the homes of canine officers to see whether they were complying with regulations. Six officers did not have the required fence, officials said.

The inspections occurred as the canine unit has come under close scrutiny by the media and the U.S. Justice Department.

The Washington Post has reported that there are at least 13 pending civil suits alleging excessive force by canine unit officers, and the FBI is investigating whether the squad engages in a pattern of excessive force. County Executive Wayne K. Curry (D) and Police Chief John S. Farrell last month announced changes in the training and supervision of the canine unit.

Canine officers are assigned police dogs, which they train with and care for at their homes.

Most of the dogs are German shepherds, and some are the similar but slightly smaller Belgian Malinois breed.

The police department provides canine officers with a kennel, a concrete slab, and a small fence that encloses the kennel, officials said.

However, a longstanding policy requires that canine officers, at their own expense, build four-foot-tall fences around the yards they keep their dogs in, for the protection of the public and the canine, said Capt. Steve Long, of the special operations division.

Such a fence would protect members of the public from wandering too close to the animals and from being bitten accidentally and also would protect the dogs from people who may have a grudge against the police and may try to feed the canines poisoned food, Long said.

Recognizing that some officers live in rural areas with yards that are measured in acres, the police department has adjusted the fence requirement, Long said.

The new standard requires that the fence be four feet tall and at least four feet away from the kennel, Long said. Estimates for erecting such a fence begin at about $700, Long said.

John A. "Rodney" Bartlett, the police union president, said the union recently filed a grievance with the county's Office of Labor. Bartlett said the police department's contract with the police union requires that the county pay for equipment officers may need, such as bulletproof vests. The fence comes under that requirement and should be paid for by the county, Bartlett said.

Bartlett said he plans to meet with police officials soon to try to reach a settlement of the dispute, hoping to avoid an arbitration hearing.