Nov. 26, 2008 -- Laura Heffron and her 10-year-old dog Tessie enjoy two half-hour walks daily. But one day in June, as they headed out the door, Tessie collapsed. Heffron headed straight for the emergency room, where X-rays showed that Tessie had arthritis in her back left knee.
Heffron knew what Tessie was in for. Heffron had been diagnosed with arthritis in both feet only five months earlier.
"Our X-rays were almost the same," Heffron said, recalling the stark black and white image of joints surrounded by a fuzzy gauze, a hallmark of arthritis.
With one in five adult dogs and 27 million Americans affected by arthritis, according to the Arthritis Foundation, the chances that a person and their longtime pet will both develop the disease are high. Going through arthritis together can be painful, but care -- and commiseration -- can help both pet and owner develop a deeper bond.
"We all slow down as we get older, and a dog is no different," said Dr. Randy Boudrieau, a professor of orthopedic surgery at the Cummings School of Veterinary Medicine at Tufts University.
Arthritis in dogs parallels the progression of arthritis in humans as the cartilage cushioning at the joints wears down, causing inflammation, stiffness and pain.
The most common problem area for dogs is the hips. Other common places for dogs to get arthritis include the knees, elbows, and the spine.
But knowing the course a pet's life is due to take can be an unwelcome realization.
Doug Van Treek, 45, from Chicagoland, Ill., was diagnosed with arthritis at age 10. Growing up, he was not allowed to play contact sports and had to manage his disease with medications.
Age reduced his activity, which included playing and exercising with his two golden retrievers, Taz, 13, and Wrigley, 11. Taz already has arthritis and Wrigley is in the first stages of the disease.
"It's difficult to see your dog go through it just like I did," Van Treek said.
Managing one's own pain and physical limitations alone can be challenging, even without the added burden of managing a pet's symptoms. It can be difficult to watch a dog change its behavior to accommodate its deteriorating body.
"It's sad. I remember her running up the hill to the house and now I see her walking very slowly," said Gail Kershner Riggs, 70, a research specialist at the University of Arizona's Arthritis Center, who has had arthritis since she was about 5 years old. "It really breaks your heart."
But even when a dog does begin to change its behavior to accommodate stiffer joints or pain, behaviors that can include difficulty sitting or standing, less interest in play, or preferring soft surfaces to lie on, an owner may not attribute such changes to arthritis until after a veterinarian's diagnosis, and even then it can come as a shock.
"I don't know that many people talk about [arthritis]," Boudrieau said. "Most clients are oblivious to whether their dogs have problems or not because the dogs don't complain."
Realizing that a loved pet will have to battle the same disease an owner will "can be pretty demoralizing," said Dr. I. Martin Levy, an orthopedic surgeon at Montefiore Medical Center in New York, who also participates in canine agility competitions. "But it can be used as a mechanism for both to recover."
Reducing body weight and moderate exercise are the best ways for people and dogs to manage arthritis.
"One of the best activities that I can think of is walking," said Dr. Joseph Guettler, an orthopedic surgeon at William Beaumont Hospital in Michigan. "I would encourage people who have a pet to walk and exercise with that pet."
Having a dog can be an added encouragement to move and exercise because it needs to be done even when someone may be feeling tired, achy and unmotivated. For most people, losing about 10 pounds can make a significant difference in their health and comfort.
"Dogs suffer from the same things humans do," Levy said, citing television and not enough exercise as common culprits of ill health. "It's a mirror image of us. I think our dogs reflect our society."
Medications and surgery to repair arthritic bones and joints can be options that help a dog's mobility and comfort.
But dogs rarely get idiopathic or very severe forms of arthritis, such as rheumatoid arthritis, like humans do, and which are difficult to treat. Overall, arthritis is not unbearably debilitating for a dog.
"Most dogs can tolerate a fair amount of discomfort," Boudrieau said, which has benefits and drawbacks. While their high pain threshold means they may not experience much pain, they are also less able to self-regulate their activity to prevent getting hurt.
"The dog's not going to know when to quit, he's having fun," Boudrieau said. "Essentially, they [owners] have to become their dog's conscience."
Owners may also cater to their dogs in other ways.
Riggs has customized her house for her 14-year-old Jack Russell, Peggy Sue, with steps for her to climb up to her favorite couch and a belly sling to lift her into the van.
"She, as I, both benefit from regular massage," Riggs said. "I give Peggy hers. Unfortunately, she cannot reciprocate."
Exercising together, making sure they are comfortable, even taking medications at the same time help arthritic owners and their dogs.
While seeing a favorite pet suffer can be painful for an owner, going through a disease, like arthritis, together can forge a sense of camaraderie and create a deeper kinship between dog and owner.
"It's made the bond so much more strong," Heffron said. "No matter where I go, she is there."