Following a month's training off the New England coast, Sea Dog sailed for Pearl Harbor to join Submarine Squadron (SubRon) 28 and prepare for her first war patrol.

A week later, she moved north into the Tokara Gunto and, on 22 October, while between the islands of Suwanosejima and Nakanoshima (Kagoshima), she sighted a convoy making eight to nine knots and zigging every five minutes.

The next 34 days were spent on station patrolling a trapezium-shaped area with Luzon, Hainan, Hong Kong and Formosa as the corners.

On 3 January 1945, Sea Dog interrupted her hunting to repair her port reduction gear, without which she was limited to single shaft operations.

Further maneuvers for a stern tube attack were frustrated when the converted escort presented a zero angle on the bow and opened fire with her forward gun, estimated to be a three-inch.

Arriving on 5 February, Sea Dog's main engines were overhauled; the 40 millimeter gun was installed in a high position forward; and ST radar equipment was added.

Assigned to patrol immediately south of the home islands, she spent 29 days in the area, with most of that time taken up in providing lifeguard services for aircraft strikes.

The next day, lifeguard duty took her on a high speed run south to the Osumi Islands, where sea planes picked up the downed pilots as she arrived.

Sea Dog remained off the Kyūshū coast for another day; then moved north to lifeguard duty south of Sagami Wan.

On arrival, Sea Dog reconnoitered the approaches to western Honshū ports to locate minefields; then took up station off the east coast of Sado Island.

Twenty-three minutes later, she made her second contact; and, at 2044, she fired three torpedoes at another merchant ship, the Shoyo Maru.

On 10 June, she closed Oga Hanto, and that night she patrolled northwest of Kisakata and northeast of Tobishima, Minato Island.

Forty-three seconds later, the torpedo hit; and the target, cargo ship Kofuku Maru, broke in two, up-ending both the bow and the stern.

That night, she took up station to the north of Nyudozaki and, at 0635 on 12 June, sighted a small convoy as it rounded that headland and continued northward, through relatively shallow waters, toward Henashi Zaki.

Leaks in the face mask of the shallow water diving outfit, however, proved impossible to repair; and, soon after 0130 on 14 June, the submarine got underway.

That night, she moved northward again, and, at 0510 on 15 June, she sighted a passenger/cargo ship standing south past the northern end of Oga Hanto.

On 17 June, Sea Dog rotated areas with Spadefish and Crevalle and headed north to hunt along the Hokkaidō coast between Bakkai and Kamui Misaki.

Two days later, she sighted three merchantmen moving northward along the coast and attacked, firing two torpedoes at the lead ship and three at the second.

For the next three and one-half months, Sea Dog operated out of Subic Bay and, on 12 January 1946, set a course for the West Coast, arriving at San Francisco, California, on 2 February.

Overhaul at Mare Island followed; and, in June, she returned to Pearl Harbor to prepare for her second postwar deployment to the Far East.

In August and early September, she provided antisubmarine training services to Seventh Fleet units in the Tsingtao area; and, at the end of the latter month, she returned to Pearl Harbor.

Through 1947, Sea Dog remained in the eastern Pacific, conducting training operations in the Hawaiian Islands and off the coasts of Washington, British Columbia, and California.

In mid-January 1948, she again deployed to the western Pacific Ocean, where, after a visit to Australia, she again joined TG 71.2, the 7th Fleet's antisubmarine warfare training group at Tsingtao.

Departing Pearl Harbor in mid-June, she arrived at Norfolk in early July and commenced training services necessitated by the outbreak of the Korean War.

In July 1952, Sea Dog was reassigned to SubRon 12 at Key West, Florida, whence she continued to provide training services.

On 7 November 1952, while conducting exercises with Airship Squadron 2 off Jacksonville, Florida, she intercepted a distress signal from a damaged U.S. Navy blimp, K-119, commanded by then-Lieutenant G. Robert Keiser, USN, and proceeded at flank speed to the last reported position to pick up Keiser and 2 other survivors, the co-pilot and navigator, for further transfer to the rescue and salvage ship USS Escape (ARS-6).

Arriving early in December, she proceeded to the Portsmouth Naval Shipyard in Maine for overhaul in January 1956; and, in May, she returned to New London, where she was decommissioned on 27 June.