All dogs may go to heaven, but one biotech startup is looking to keep labradors and other bigger canines on Earth longer.

A drug to extend the lifespan of large dogs — who live about half as long as smaller breeds — could be on the market in coming years, according to Loyal, a San Francisco biotech company developing longevity treatments for canines. 

The Food and Drug Administration Center for Veterinary Medicine has found a reasonable expectation of effectiveness for the drug, codenamed LOY-001, Loyal announced Tuesday in a news release, a big step toward its full approval. The development is "a first for any longevity drug, and is a big step towards accelerating the path for canines, and ultimately humans," stated Vinod Khosla, founder of Khosla Ventures, an investor in Loyal. 

Designed to reduce levels of a growth-promoting hormone thought to shave years off the lives of large and giant-breed dogs, the drug would be administered by a veterinarian every three to six months and is expected to be available in 2026, pending FDA approval of the company's manufacturing and safety data, Loyal stated. 

The FDA did not immediately respond to a request for comment. 

According to the American Kennel Club, Great Danes and Newfoundlands typically live seven to eight years, while smaller dogs — think Chihuahuas and Miniature Poodles — live an average of 20 years.

The inverse relationship between the size of a dog and the animal's expected lifespan is not natural, but the result of breeding dogs to herd, protect and be good companions, according to Brennen McKenzie, Loyal's director of veterinary medicine and a practicing veterinarian. "We see the short lifespan of big dogs not as inevitable, but as a genetically-associated disease caused by historical artificial selection, and therefore amendable to targeting and treatment with a drug," McKenzie said in the Loyal release.

Historical selective breeding is among the causes of genetically-associated diseases, such as cancer in Golden Retrievers, hip dysplasia in German Shepherds and canine brachycephalic syndrome in Bulldogs, the company noted. 

Loyal is not alone in looking for ways to extend the life of man's best friend.

Affiliated with the University of Washington, the Dog Aging Project is conducting a canine clinical trial of rapamycin, a drug that has shown promise in increasing the lifespan and delaying age-related disorders in mice. 

Kate Gibson

Kate Gibson is a reporter for CBS MoneyWatch in New York.