Please choose the correct ending to complete the given sentence: Pets and Animals: [header] How to treat heart failure in dogs [title] Restrict the amount of exercise your dog gets each day. [step] When a dog has a weak heart, exercise can add extra pressure to his condition. Heart failure can lead to difficulty with blood circulation, meaning that your dog's vital organs do not get enough oxygen.

Ending1: Limit how much exercise your dog gets each day. [substeps] For example, if you only take your dog for walks every day, it will be a good time to plan walks with your dog to tire it out and build it up again. Ending2: If your dog has heart failure, he should not be allowed to exercise heavily, though he can still wander around the yard. Forgo taking him on walks for peaceful hours petting him or letting him lounge. Ending3: If this becomes a problem for your dog, restrict the amount of activity your dog can do each day. [substeps] For example, if your dog weighs 50 pounds, try not to exercise this much each day. Ending4: Limit the amount of exercise your dog gets each day and avoid the following : [substeps] Walking. Your dog should walk around for several minutes every day.

Answer format: ending1/ending2/ending3/ending4