We love to play fetch and explore the outdoors with our dogs. But for many pets, physical activity can be uncomfortable or even painful over time. This is often because of arthritis, a degenerative joint disease.

Arthritis affects 1 in 4 pet dogs in the United States. This surprising statistic indicates that many of our dogs may be experiencing the pain of arthritis without us even knowing it. How can you tell whether your dog has arthritis? Keeping reading for the 4 major signs of arthritis in dogs. And remember: If you think your dog has arthritis or they appear to be in pain, be sure to take them to a veterinarian. It’s helpful to identify arthritis in dogs, but treatment should always be left to the professionals.

1. Hesitation moving

When getting out of bed or walking up the stairs becomes difficult for your dog, it’s likely something’s not right. According to the American College of Veterinary Surgeons, hesitation moving is a major symptom of arthritis in dogs. It’s important to watch for initial hesitation to move, as well as difficulty getting up or climbing stairs.

2. Limping

Once your dog is up and moving, limping or a strained gait is another symptom of arthritis. What is the reason for this? South African scientists explain that osteoarthritis is the most common type of arthritis in canines and that this disease is characterized by the degeneration of cartilage. Cartilage is made of naturally-occurring substances like glucosamine and chondroitin, which can be supplemented in your pet’s diet to combat degeneration.

The occurrence of cartilage degeneration can often make walking more difficult. If your dog is limping, hopping, or exhibiting other strained walking behaviors, it’s possible they have osteoarthritis.

3. Irritability

According to Dr. Natalie Waggener from the South Boston Animal Hospital, dogs handle pain much like humans do. In other words, they can get a little grumpy when their body hurts. If your pooch is snapping more than usual—especially when touched near the hips or other joints—they may be suffering from arthritis pain.

4. Thin legs

Veterinarians explain that muscle atrophy is another major symptom of arthritis in dogs. Muscle atrophy is the decrease of muscle tissue in the body—particularly, the legs. If you notice your dog’s legs looking thinner than normal, it’s a good idea to get them checked for arthritis.

Arthritis in dogs is overwhelmingly common…but that doesn’t mean your pooch needs to suffer. Visiting a vet to start managing pain is an important first step.

Before your dog develops arthritis, however, there are several ways to reduce his risk of disease. To begin, research that obesity can be a major cause of arthritis in dogs. Scientists suggest that dietary strategies can be a successful approach to weight loss in dogs, such as feeding pets lean food and treats.