A search-and-rescue (SAR) dog is a dog trained to respond to crime scenes, accidents, missing persons events, as well as natural or man-made disasters. These dogs detect human scent, which is a distinct odor of skin flakes and water and oil secretions unique to each person and have been known to find people under water, snow, and collapsed buildings, as well as remains buried underground. SAR dogs are a non-invasive aid in the location of humans, alive or deceased.

Cadaver dogs are working search-and-rescue dogs, specially trained to locate decomposition scent, specific to human decomposition. Also known as Human Remains Detection Dogs (HRDDs), cadaver dogs are employed in forensic contexts to sniff and locate human remains, which can include those that are buried, concealed, or older, as well as body parts, skeletal remains, and soil contaminated with decomposition fluid. Differently to other types of tracking dogs that use scents on the ground or specific items, cadaver dogs are trained to locate both ground and airborne scents, and notify of the area where the scent concentration is highest.

In Croatia, such dogs have been used to find burial sites almost 3000 years old. More recently, HRDD's have been used in Canada and the United States to locate unmarked graves of Indigenous children around former residential school sites. Law enforcement, medical examiners and anthropologists often work closely with cadaver dogs and their handlers, to coordinate searches and evidence and/or body recovery.

As early as the 17th century, St. Bernard dogs were used by monks at the St. Bernard Hospice in the Swiss Alps, to search for and rescue injured or lost travelers, or find their remains. However, official search and rescue dogs were not first documented for use until WW1, when military trained dogs were used to locate injured soldiers. During WW2, these dogs were used by the British armed forces to locate people buried under rubble.

The history of cadaver dogs is more recent. In 1808, an untrained dog alerted to the shed of a murder suspect, which led to the discovery of the remains of 2 missing women. However, the first use of a dog trained exclusively for cadaver searches in forensic casework was not until 1974 by the New York State Police, when they investigated a homicide in Oneida county, which involved multiple victims buried in a large forested area. From there, training programs were developed, and now specialty cadaver dogs are trained and maintained by police organizations, as well as numerous volunteer search dogs teams.

Common dog breeds used for search-and-rescue work include German Shepherds, Labrador Retriever, Border Collies and Golden Retriever. Most often, purebred dogs are chosen, as it allows a clearer understanding of their potential working abilities, and possible genetic problems. Individual dogs are selected for behaviors related to successful field work, which can include, but is not limited to:

Physical characteristics, such as coat and stamina, are also taken into consideration when selecting the appropriate dog for the job.

Many training methods used in SAR training are based on the methods developed to train military dogs during WW1 and WW2. Training of a search dog usually begins when the dog is still a puppy. Training begins with "scent games" when a puppy is 10–12 weeks old. "Hide and seek" activities are introduced as the dog ages, to simulate people lost in disasters. Most SAR dogs, regardless of their task, will spend around 12–18 months in training, for 20 or more hours a week. Some US states require certification before deployment.