Almost never for the injury itself: a torn cruciate is painful and disabling but it is treatable, and even without surgery many dogs reach a livable result with strict management. Euthanasia enters the honest conversation only when a cruciate rupture lands on top of other serious problems, severe arthritis everywhere, major illness, extreme age, or when every treatment pathway is genuinely beyond a family's means and rehoming is not realistic.
If the money is the blocker, read the options before deciding: lateral suture surgery in the right dog costs a fraction of TPLO, structured conservative management costs mostly discipline, and payment plans and charity clinics exist. A $250 independent opinion on which cheaper pathway is legitimate for your dog is a very small spend against this decision.
If you are at this page because a vet has genuinely recommended euthanasia over a knee injury alone, in an otherwise healthy dog, get a second opinion before you act on it. That recommendation is unusual enough to deserve one.
Many can, especially smaller and lighter dogs. Conservative management means strict rest for weeks, weight loss if the dog is carrying extra, anti-inflammatory pain relief and a gradual, controlled return to lead walking, ideally with a physio plan. The knee stabilises with scar tissue rather than a repair, so arthritis is likely to follow and the result is less reliable in big, active dogs. It is a legitimate pathway, not a failure, and we cover it in detail in can a dog live with a torn cruciate.
Usually a lateral suture (extracapsular repair) at an experienced general practice. It suits smaller and calmer dogs best and costs well under a TPLO. Beyond that, ask the clinic about payment plans, check whether a veterinary teaching hospital or charity clinic operates near you, and read when you cannot afford surgery. Which cheaper option is honest for your dog depends on its size, age and activity, which is exactly what a written second opinion settles.
Age alone is rarely the deciding factor; the dog's other health problems are. A twelve year old with a sound heart, kidneys and a single bad knee is a reasonable surgical candidate. A dog with severe arthritis in every joint, a serious illness or a short expected lifespan is a different conversation, and that is where the euthanasia question becomes legitimate. If you are unsure which description fits your dog, send what your vet said and quoted and a surgeon will tell you plainly.
Send what your vet said and quoted. A veterinary surgeon reads it and comes back to you with what they can do and what it would cost, before you pay anything. A written second opinion is from $250.
Send the case, hear back from a surgeon with what they can do and what it costs, and only pay if you go ahead.