Bacon, a cream-colored retriever mix, took a behavior test recently at an animal shelter here. He flunked.
Bounding into the evaluation room, Bacon seemed like an affable goofball, ready for adoption. But as he gulped down food, Dr. Sara Bennett, a veterinary behaviorist, stuck a fake plastic hand attached to a pole into his bowl and tugged it away. Instantly, Bacon lunged at the hand, chomping down on it hard.
Shelters have used this exercise and others for some 20 years to assess whether a dog is safe enough to be placed with a family. For dogs, the results can mean life or death.
“If you failed aggression testing, you did not pass go,” said Mary Martin, the new director of Maricopa County animal shelter in Phoenix, which takes in 34,000 dogs annually. Between January and June 2016, 536 dogs were euthanized for behavior, most because of test results.
But now researchers, including some developers of the tests, are concluding that they are unreliable predictors of whether a dog will be aggressive in a home. Shelters are wrestling with whether to abandon behavior testing altogether in their work to match dogs with adopters and determine which may be too dangerous to be released.
In January, Ms. Martin stopped the testing. By late June, only 31 dogs had been euthanized for aggression, based on owner reports and staff observations.
“The tests are artificial and contrived,” said Dr. Gary J. Patronek, an adjunct professor at the veterinary medicine school at Tufts, who roiled the shelter world last summerwhen he published an analysis concluding that the tests have no more positive predictive value for aggression than a coin toss.
“During the most stressful time of a dog’s life, you’re exposing it to deliberate attempts to provoke a reaction,” Dr. Patronek said. “And then the dog does something it wouldn’t do in a family situation. So you euthanize it?”
The debate over how dogs should be evaluated arrives as efforts to generally improve outcomes for shelter animals are on an upswing. According to the American Society for the Prevention of Cruelty to Animals, annual adoption rates have risen nearly 20 percent since 2011 — a period during which owning a “rescue dog” acquired something of a righteous hipness. Euthanasia rates are down, although the A.S.P.C.A. said 670,000 dogs are put to death each year. Some veterinary schools even offer shelter-medicine specializations.
Shelters are helped by a burgeoning network of rescue groups. They shuttle dogs from high-kill shelters, usually in the South and Southern California, often to foster homes and adopters in the Northeast and Northwest, where spaying and neutering campaigns have reduced puppy availability.
It is impossible to know how many euthanized dogs scored false positives on behavior testing. Though rare, false negatives also can occur and have proved tragic. In December, workers at Animal Care Centers of New York City saw nothing remarkable on a standard behavior test of a dog named Blue, but noted that he had been surrendered for biting a child. A rescue group retrieved him. Blue eventually wound up in a retraining center in Virginia. On May 31, he was finally adopted; hours later, he attacked and killed a 90-year-old woman.
Some high-volume shelters cannot afford time for evaluations, much less daily walks for dogs; others have begun de-emphasizing their significance. Even Emily Weiss, the A.S.P.C.A. researcher whose behavior assessment is one of the best-known, has stepped away from food-bowl tests, saying that 2016 research showed that programs that omit them “do not experience an increase in bites in the shelter or in adoptive homes.”
Still, Jennifer Abrams, head of the behavior and enrichment staff at Animal Care Centers of New York City, which sees 8,900 dogs a year, said that anxious adopters needed assurances. “People want to know what they’re getting — that a dog won’t bite, yell and scream at other dogs on a leash,” she said.
But predicting an animal’s behavior belies the nature of dogs, Ms. Abrams said: “A dog’s behavior is based on stimuli in the moment.” Ms. Abrams’s team conducts assessments, considering them snapshots, while gathering information throughout the animal’s stay.
In the surge to modernize shelters, tests were an attempt to standardize measurements of a dog’s behavior. But evaluations often became culling tools. With overcrowding a severe problem and euthanasia the starkest solution, shelter workers saw testing as an objective way to make heartbreaking decisions. Testing seemed to offer shelters both a shield from liability and a cloak of moral responsibility.
“We thought we had the magic bullet,” said Aimee Sadler, a shelter consultant. “‘Let’s let Lassie live and let Cujo go.’ From a human perspective, what a relief.”
The 10- to 20-minute tests, developed by behaviorists and tweaked by practitioners, ask two basic questions: Will the dog attack humans? What about other dogs?
Evaluators may observe the dog react to a large doll (a toddler surrogate); a hooded human, shaking a cane; an unfamiliar leashed dog or a plush toy dog.
But these tests have never been rigorously validated.
Dr. Bennett’s 2012 study of 67 pet dogs, which compared results of two behavior tests with owners’ own reporting, found that in the areas of aggression and fearfulness, the tests showed high percentages of false positives and false negatives. A 2015 study of dog-on-dog aggression testing showed that shelter dogs responded more aggressively to a fake dog than a real one.
Janis Bradley of the National Canine Research Council, co-author with Dr. Patronek of the analysis published last fall, suggested that shelters should instead devote limited resources to “observing the many interactions that happen between dogs and people in the daily routine of the shelter.”
But Kelley Bollen, a behaviorist and shelter consultant in Northampton, Mass., maintained that a careful evaluation can identify potentially problematic behaviors. Much depends on the assessor’s skill, she added.
In fact, no qualifications exist for administering evaluations. Interpreting dogs, with their diverse dialects and complex body language — wiggling butts, lip-licking, semaphoric ears and tails — often becomes subjective.
Indianapolis Animal Care Services, which admitted 8,380 dogs to its municipal shelter in 2016, is often overcrowded and understaffed, yet faces intense scrutiny to save dogs while protecting the public. Last year it euthanized 718 dogs for behavior, based on testing and employee interactions. The agency consulted Dr. Bennett, a shelter specialist, to better manage that difficult balance.
Even as she demonstrated assessments for staff members, Dr. Bennett noted another factor that renders results suspect: the unquantifiable impact of shelter life on dogs.
Dogs thrive on routine and social interaction. The transition to a shelter can be traumatizing, with its cacophony of howls and barking, smells and isolating steel cages. A dog afflicted with kennel stress can swiftly deteriorate: spinning; pacing; jumping like a pogo stick; drooling; and showing a loss of appetite. It may charge barriers, appearing aggressive.
Conversely, some dogs shut down in self-protective, submissive mode, masking what may even be aggressive behavior that only emerges in a safe setting, like a home.
Little dogs can become more snippy. But no matter what evaluations may show, they always seem to get a pass. “I’ll warn, ‘He nips and snarls,’” recounted Laura Waddell, a seasoned trainer who does volunteer evaluations for Liberty Humane Society in Jersey City, N.J. “And I get back: ‘I don’t care! I’m in love!’”
One way to reduce kennel stress, Ms. Sadler, the shelter consultant, said, is through programs like hers, Dogs Playing for Life, which matches dogs for outside playgroups. Shelter directors say it is a more revealing and humane way to evaluate behavior. The approach is used at many large shelters, including in New York City, Phoenix and Los Angeles.
The most disputed of the assessments is the food test. Research has shown that shelter dogs who guard their food bowls, as Bacon did, do not necessarily do so at home.
The exercise purports to evaluate “resource guarding” — how viciously a dog will protect a possession, such as food, toys, people. Common-sense owners wouldn’t grab a dog’s food while it is eating. But shelters worry about children.
Dr. Bennett suggested that Bacon’s bite of the fake hand didn’t necessitate a draconian outcome. With counseling, she said, a household without youngsters would be fine.
The shelter workers dearly wanted to save Bacon. But they were so overwhelmed that they did not have the capability to match him appropriately and counsel new owners.
So Bacon remained at the shelter for several weeks, waiting. Finally, Linda’s Camp K9, an Indiana pet-boarding business that also rescues dogs, took him on. He settled right down and recently was adopted. Linda Candler, the director, placed him in a home without young children, teaching the owners how to feed him so he wouldn’t be set up to fail.
“His potential made him stand out,” Ms. Candler said. “Bacon is amazing.”