When Lorraine Fields of Alexandria noticed recently that her two-year-old black Labrador retriever Maria was having trouble seeing, she did what many concerned pet owners would do.

She loaded the dog and here two young children into the family car and drove to a nearby clinic where a verterinarian diagnosed bacterial conjuctivitis and bathed Maria's eyes.

The examination and treatment, valued at $12 to $15 by several veterinarians, didn't cost the Fields family a cent.

As the wife of a Navy lieutenant commander, Fields is one of an estimated 500,o00 Washington area residents who qualify for a little-know but controversial benefit: no-cost or low-cost care for their pets at military-run veterinary clinics. More than 1,200 pets were treated at the five local military veterinary clinics last month.

This year alone, American taxpayers will spend an estimated $57 million to pay the salaries of 667 Army and Air Force veterinarians and the 2,000 enlisted personnel who serve as their assistants. Although the other military services do not have veterinary corps, their members are entitled to used Army and Air Force services.

"The Department of Defense is probably the only organization in the world which provides pet care as a fringe benefit," said Rep. Les Aspin (D-Wis), a frequent military critic and member of the House Armed Services Committee.Aspin recently attacked the clinics as "just one of many little freebies hidden in the Defense budget."

The military defends the services it provides to pet owners as part of its public health mission. Humans, the military point out, can contract diseases from pets.

"Pets provide a stabilizing influence and we certainly don't want to discourage our Gis from having pets," declared Col. George H. Wyckoff Jr., chief clinic veterinarian at the Walter Reed Army Medical Center here. "But our GIs have to be healthy because at any moment they may be asked to go to Nicaragua or Egypt."

The Veterinary Corps is a legacy of the days of the cavalry when military veterinarian were needed to care for many thousands of horse and mules. Today, its function has changed and veterinarians inspect food sold in commissaries and packaged for combat rations, and care for the 2,000 government-owned horses and guard dogs. Some do research at various installations, including Watler Reed.

In the name of public health, military veterinarians also are authorized to perform a wide variety of medical procedures for pets of the nation's estimated 8 million to 12 million active duty and retired military personnel and their families.

A recent study showed that military veterinarians spend about 20 percent of their time caring for pets and in disease control.

The study also says veterinarians spend half their time on administrative tasks associated with running the clinics and supervising inspections.

Clinic operations and veterinary treatment available vary somewhat around the nation, but officials say that military families like the Fields who took their dog to the Ft. Belvoir clinic -- are charged only for the cost of drugs and materials used in treating their pets.

While civilian vets may impose a 100- to 300-percent markup for drugs and treatment, military vets charge nothing for their services because their salaries and the buildings in which they work are subsidized by taxpayers. Drugs and materials are subject to only a 10- to 25-percent markup in the military clinics. That money is used to replace these items and to run the clinics.

Local civilian and military veterinarians say that this results in savings like these:

At Fort Belvior, heartworm treatments for dogs cost $20; civilian veterinarians commonly charge $80 to $120.

Charges of $12 for an office visit and at least $5 to board an animal overnight after treatment are common, according to several civilian veterinarians. In military clinics, office visits are free and the boarding charge is $1.

Combined rabies and distemper shots for dogs cost $7 at military clinics. Local veterinarians report charges ranging from$18 to $24.

If the Army wants its vets to inoculate the general's poodle, fine, let them," said Congressman Aspin, "but let the general pay the going rate. There no reason why the pet owner in uniform should get a $10 service for $1."

Veterinary Corps officials vehemently dspute Aspin's statements. "We are not in the business to be a convenience or a fringe benefit," said Col. Wycoff of the Walter Reed clinic.

"Most of the people whose pets we treat are not generals but [low- and middle ranking ] enlisted personnel," said Wyckoff, pointing to the clinics' public health function.

According to Wyckoff, military veterinarians are empowered to treat and prevent diseases in pets that can be contracted by humans, such as common skin and parasitic infections as well as rabies and distemper, for which inoculations are provided. Veterinarians can also perform emergency surgery on pets to prevent or relieve pain.

"The services we provide," Wyckoff said, "are all directly related to public health."

"You can justify anything that way," said Rep. Joseph Addabbo (D-N.Y.), chairman of the defense subcommittee of the House Appropriations, Committee. Later this month Addobbo said, that subcommittee will recommend merging the two veterinary corps as well as reducing the staff by 40 percent.

The subcommittee is expected to base its action largely on a recent 200-page study by Maximus Inc., a McLean consulting firm hired by the Defense Department to study the corps.

The report, submitted to the subcommittee last spring, says that:

In World War I there were 400 government-owned animals for each military veterinarian. Today that ratio is four to one.

In 1977 the Defense Department spent twice as much money to operate pet clinics as it spent on food inspections and care of government-owned animals combined.

Enlisted technicians perform most food inspections. Veterinarians are called only when unusual problems occur and involve only one percent of food inspected.

Although there are 150 animalborne diseases that may be transmitted to humans, "the incidence and prevalence of these disease indicate that they are under control," In 1977, for example, there was one reported rabies death in the U.S.

Military officials say that if the cuts recommended by the subcommittee are approved by Congress, they may force reductions in the services provided by the five Washington area clinics.

In addition to Fort Belvoir and Walter Reed, these clinics are located at Andrews Air Force Base in Prince George's County, Fort Myer in Arlington and Quantico Marine Base in Prince William County.

The possible cuts anger some military pet owners who see them as an "erosion of benefits."

"It's just another thing that's being taken away from us, another benefit that's being eroded," said Judy Kowal of Alexandria, whose husband is an Army staff sergeant. "We used to have total vet care, but when I called Fort Myer recently to have my dog and cat spayed, they said they were discounting the service."

In the last five years, according to Pentagon officials, there have been 17 studies of the veterinary corps, which has been the subject of a bitter fight within the Defense Department itself.

In 1975 and again in 1978, the Defense Audit Service recommended that Military personnel in most areas be required to take their pets to civilian veterinarians for routine treatments.

Last year a recommendation by two assistant secretaries of defense to drastically cut the corps was reversed by Defense Secretary Harold Brown following what one Pentagon official called "a lobbying blitz" by veterinary officers and sympathetic Congressmen. CAPTION: Picture, Lorraine Fields (right) and her daughter, Sara, look on as a military doctor examines their dog, Maria. By Larry Morris - The Washington Post.