There's no way around it: Putting down a pet is one of the most difficult decisions a pet parent can make. When is it time to put your dog or cat down? As you can probably guess, there's no completely right or wrong answer. The right time will depend on multiple factors, such as your pet's quality of life, your quality of life and whether your pet has a certain health condition or ailment.
When to Put a Dog or Cat Down: Things to Consider
Though the decision is always a sad one, in some situations, putting down a pet can be the most humane choice. Remember that your veterinarian is your best resource for non-judgmental and expert advice. If you're facing the question of when to put down a dog or when is it time to put your cat down, consult your vet. Below are just some things to consider when facing this difficult decision.
Terminal Disease
One of the most obvious reasons to consider humane euthanasia is when a pet has a terminal disease, such as heart failure, cancer or another incurable condition. It's important to talk to your veterinarian about how they will manage the disease — in some cases a specialist may be necessary. Make sure to ask your veterinarian tough questions like such as whether or not the management of the disease compromises your pet's quality of life, even if it does extend it. In these cases, when your pet's health will continue to decline, helping them pass peacefully can be the last gift that you give your beloved pet.
Uncontrolled Pain or Loss of Mobility
Many pets, especially large dogs, can develop osteoarthritis — a progressive, painful degeneration of their joints. This condition can make it difficult and painful to walk, run, get up and down, jump and climb stairs. This disease can be especially distressing because dogs with osteoarthritis can be otherwise healthy in body and mind. Sometimes pet parents will wait longer to let go of their pets in these cases because it is hard to know just how much pain their pet is in.
If your pet is dealing with pain or loss of mobility that's no longer responding to treatment, talk to your vet. There might be other options or it may be time to discuss end-of-life care.

Untreatable Aggression or Behavioral Disease
Sometimes, despite pet parents' best efforts, dogs and cats can develop behavioral problems that put them, other pets and/or people in danger. Your vet may recommend humane euthanasia for safety and human health reasons. Behavioral issues in themselves are never a reason to euthanize a pet, but in cases where they cannot be corrected despite all your efforts to help, and they pose a threat to other pets or people, your veterinarian or a veterinary behaviorist is the best person to consult at this time. These cases are often especially emotionally difficult.