Both Hips at Once, or One at a Time? What the Bilateral Series Show for Hip Replacement, Pelvic Osteotomy and FHO, and Why 'We'll See' Is Usually the Real Plan

If both hips are bad, the operation decides the schedule more than the surgeon does. Hip replacement is done one side at a time almost everywhere, with the second side decided after the first has healed, and at one teaching hospital four dogs in five never need it. Pelvic osteotomy is the opposite: the largest series did both hips in one 95-minute session and the dogs walked by day four. FHO sits in between: both at once has been done in a 15-dog series with owners reporting pain-free dogs, and it has no implant to protect, but a large dog with two fresh cuts and no good leg is a recovery the household has to be ready for. The rest of this page is what each series actually measured, why the "how many need the second hip" numbers disagree, and the one finding that should change how you read your own surgeon's "we'll see."

The sentence you were probably sent home with was "we'll do the worse side first and see how he does." It sounded like good news, and it is, but the part you heard was "he may not need the other one," and whether that is true depends on which surgeon's number you were given. One teaching hospital puts it at 80%. One private hip replacement practice says most dogs with pain on both sides get both done. Both are telling the truth about the dogs they counted. Reading the two against each other is the most useful thing on this page, because it tells you what "we'll see" is actually waiting to see.

What the three schedules are, and the third one nobody names#

Two bad hips give a surgeon three schedules, not two. Single-session means both hips under one anaesthetic. Staged means one hip now and the other some weeks or months later. The third option is the one that is rarely written on the estimate but is where most staged plans end: one and done, where the second hip is never operated because the dog is comfortable enough on the first. It is a legitimate outcome, not a failure, and it is the reason the "we'll see" is honest. But it is only honest if somebody actually looks, on a date, at something measured. We come back to that.

Which schedule you are offered depends far more on the operation than on your dog, so the three operations are taken one at a time.

Hip replacement: one side at a time, and the number that decides the second#

Total hip replacement is the operation with the clearest convention and the least evidence for it. We could not find a canine series of both hips replaced in one session, and the 1,852-dog multi-centre registry, the largest published, reports that 523 dogs (28%) had bilateral replacements; its abstract, which is what we read, does not say whether any were done in one session.^[1] The hospital pages say why in plain words. Iowa State's hip replacement service: "Only one hip is operated at first, usually the clinically most effected side," and "the decision to operate the second side is made after recovery from the first."^[2] The one practice we found that states an interval says the surgeries "are almost always staged about 6 weeks to several months apart," with the most painful hip first.^[3] The American College of Veterinary Surgeons' hip dysplasia page, read the same day, says nothing about bilateral scheduling at all.^[4]

So the question for a hip replacement owner is not "both at once or not." It is "will he need the second one," and here the sources appear to disagree by more than a factor of two.

The disagreement is in the denominators, not the dogs. The Austin page says "the majority of dogs" with hip dysplasia "are affected in both hips, although one hip is typically worse clinically,"^[5] so "20% of dogs with bilateral arthritis need both" is a statement about a wide group. "Over half of dogs painful on both sides" is a statement about a much narrower one, the dogs already limping on both. The registry and the 1,105-dog series count every dog that ever had a replacement; in the registry that includes the 15% operated for something other than dysplasia or arthritis, such as a fracture or a luxation, so their 25 to 28% sits between the two. Read together, they say something more useful than any one of them: if your dog's second hip is arthritic on film, the odds favour never operating it; if it is already painful, the odds favour operating it eventually. The film is not the decision. The pain is.

dogorthopedic.com

The same owner, twice#

The 2011 paper that produced the 25% figure was not written to answer that question. It was written to measure the delay, and it found something this site has been trying to say for a long time. In 833 dogs with one hip replaced, the authors measured how long the dog had been lame before surgery. Then, in 272 dogs that went on to have the second hip replaced, they compared that first delay to the gap between the two surgeries. The interval between the surgeries was significantly shorter than the time the owner had waited before the first.^[6]

Same dog. Same disease. Same owner, same surgeon. The paper measured the difference and does not explain it, and there are two honest explanations that it cannot separate. The dog-side one is that the second hip was already painful when the first was operated, so there was less to wait for. The owner-side one is that the owner had now watched what the operation gives back. We think the second is a large part of it, and we say that as our reading rather than the paper's finding. The same owner waited less the second time, and the only new information she had was what a fixed hip looks like. That is the whole argument for reading before you have to.

“Because your dog can't tell you how much pain he or she is in.”

The same paper found the delay before the first surgery got longer between 1992 and 2009, which its authors put down to better medical management and changing recommendations.^[6] Better drugs make waiting more comfortable. They do not make it free.

What a second replacement risks#

A second hip replacement is a second exposure to the same complication rate. In the registry, surgeons reported complications in 8.5% of replacements and owners in 23% of the ones they were asked about, with only moderate agreement between the two, and no association between complications and weight, age, sex or breed.^[1] Whichever figure you believe, it applies per hip. Nobody has measured whether a dog's second replacement carries a higher or lower rate than the first, so we do not say it does either way.

You will find a large human literature arguing that doing both hips under one anaesthetic is safer and cheaper: a 2022 meta-analysis of about 104,000 patients found fewer overall complications, less blood loss, shorter stays and lower total cost with simultaneous surgery, at the price of more pulmonary embolism and periprosthetic fracture.^[7] It is worth knowing that this evidence exists, and worth knowing that none of it is about dogs, who do not lie in a hospital bed for a week and cannot be told to use a walking frame. It is not a reason to ask your surgeon to do both.

Pelvic osteotomy: the operation where both at once is routine#

Everything above inverts for the growing dog whose hips are loose but not yet arthritic, the candidate for a double or triple pelvic osteotomy. Here both sides in one session is not an outlier; it is the largest series. Ninety-five dogs, mean age 10.8 months and mean weight 35 kg, had triple pelvic osteotomy on both hips under one anaesthetic. Mean surgical time for both sides was 95 minutes. All but one dog walked unaided by the fourth day, mean hospital stay was 7.5 days, iliac bone healing took a mean of eight weeks, and 19 dogs had complications, all of them minor; seven of 1,520 screws loosened and no plate did.^[8] The developers of the double pelvic osteotomy also report bilateral cases in their first series, 53 joints in 34 dogs, and write that morbidity "after unilateral and bilateral DPO was lower than after TPO."^[9] Whether those bilateral cases were done in one session is not in the abstract, which is what we could read, so we do not say.

The reason the schedule flips is the disease clock. A pelvic osteotomy only works before arthritis starts, and the ACVS puts the candidate at "ideally less than 8–10 months old";^[4] we cover the candidate criteria in DPO or TPO for the puppy who missed the JPS window. Staging a second hip six weeks later in a nine-month-old puppy spends the window. Both at once is not bravado. It is the calendar.

The one complication that belongs specifically to bilateral pelvic osteotomy is worth knowing by name, because it has been blamed on single-session surgery and the case reports do not support that. Rotating both sides of the pelvis can narrow the pelvic canal enough to press on the urethra. It has been reported in two dogs after single-session bilateral TPO,^[10] in an eight-month-old Golden Retriever after single-session bilateral TPO,^[11] and in a five-month-old Labrador after staged bilateral TPO.^[12] Two of the three call it rare; all three needed surgery to fix. The risk is in rotating both halves of the pelvis, whenever you do it. If your puppy strains to urinate after either side is done, that is a same-day call, not a wait-and-see.

FHO: both at once has been done, and what "done" means#

The femoral head and neck ostectomy removes the ball and the neck and puts nothing back; the dog builds a fibrous false joint, and our FHO recovery timeline covers what that looks like week by week. Because there is no implant to protect and no cut bone that has to unite, some surgeons will do both hips in one session, and there is one canine series of exactly that: 15 dogs with severe bilateral dysplasia, surveyed six to 48 months later. By owner report, all had normal activity levels and were pain free, and satisfaction was high. The authors' own framing of when it is the right choice is worth quoting: "especially when other surgical options were not indicated or were cost prohibitive."^[13] It is the budget answer to two bad hips, and the series says the budget answer works, as judged by the people paying for it.

Two cautions belong next to that. First, it is 15 dogs and a questionnaire; the only perioperative series of single-session bilateral FHO with actual complication counts that we could find is in cats, 39 of them, discharged within 48 hours with one major and five minor complications.^[14] A cat is not a dog, and a four-kilogram cat is not a 40-kilogram dog. Second, owner satisfaction and measured function are different instruments. In the Munich FHO follow-up, 132 dogs and 51 cats were operated, and 81 of those animals (44%) were re-examined an average of four years later; among the animals re-examined, the functional result was rated good in 38%, satisfactory in 20% and poor in 42%, yet 96% of owners were satisfied. Gait analysis in 17 of the re-examined animals showed the operation relieved pain at the cost of functional deficits in small and large dogs alike, deficits not visible at speed.^[15] A knowledge summary that went looking for a direct comparison of pain after replacement versus after bilateral FHO in large young dogs found none, rated the evidence weak, and could not say which is better at reducing long-term pain.^[16] "All the owners were happy" is true and it is not the same sentence as "the dogs walked normally."

He had both hips done and now seems hurt again#

This is one of the questions that brought people to this site, in almost exactly those words, and it deserves a straight answer rather than a timeline. After a bilateral FHO there is nothing to break in the way a plate or a stem breaks. A dog who was improving and has a bad few days in the first weeks has almost always done a soft-tissue thing: a slip on a hard floor, a stair taken too fast, a play session nobody sanctioned, muscle that is being asked to do a job it has not rebuilt for. The right response is a short reduction in activity and then back to the plan, because with an FHO the plan is movement; rest is what makes the false joint stiff. Our FHO recovery page explains why crate rest is the wrong instinct for this operation specifically.

What should not be filed under setback: a dog who had started using both legs and stops using one, a dog who cries when the leg is extended behind him, or a large dog who is still plainly painful months out. There is a documented reason for the last of these. A CT study of four large dogs with poor long-term FHO outcomes, each operated at a different clinic, found extensive remodelling, "unacceptable bone-on-bone contact" between what was left of the neck and the socket, and in one case too much bone removed; one dog had a revision cut and did not improve.^[17] Four dogs is a case series, not a rate. But it means that "he had the operation, so the pain must be something else" is not a safe assumption in a big dog, and the question to ask is whether films or a CT of the cut would change anything. With both hips done, there is no un-operated side to blame, which makes the answer easier to get.

dogorthopedic.com

The one canine comparison that exists is in a different joint#

We looked for a study that put single-session, staged and unilateral surgery side by side in dogs' hips and found none. The one that exists is in knees. Ninety-three dogs with bilateral medial patellar luxation had either unilateral surgery (65), staged bilateral (16) or single-session bilateral (11). Complications occurred in 24% of stifles and 9% needed revision, and there was no significant association between the timing of surgery and the complication rate; the authors concluded single-session surgery is feasible in dogs under 10 kg.^[18] That is a small-dog knee study with 11 dogs in the group that matters, and it does not transfer to a 40 kg hip. We include it because it is the honest size of the canine evidence on the timing question: one study, wrong joint, not significant.

What one session costs and what two sessions cost#

Nobody has measured, for dogs, whether one long anaesthetic is safer than two shorter ones. What exists is the base rate. In the largest prospective study of anaesthetic death in dogs, about 98,000 anaesthetics across 117 practices, the risk of anaesthetic-related death within 48 hours was 0.17% overall and 0.05%, about 1 in 1,850, in healthy dogs.^[19] Two surgeries is that exposure twice. One surgery is that exposure once, for longer. Nothing in the canine hip literature tells you which is the smaller number, and we will not pretend the human data does. That is a question for the anaesthetist at the practice that will do the work, and "what is your plan for a 95-minute bilateral in a dog this size" is a reasonable thing to ask them.

On money, the pattern is the same as for every hip operation on this site: no teaching hospital publishes a fee, and the blog ranges cite nothing, so we repeat none of them. What you can control is the estimate. Ask that it states in writing whether it covers one hip or both, one session or two, and what the second session costs if it is staged, and, if both are being done at once, how the one anaesthetic and one hospital stay are priced against two. Our list of questions for the orthopedic consult has the rest.

The cost the literature never measures is the one the household pays. A staged plan is two recoveries, each with a good leg to lean on. A single-session plan is one recovery with none. That is a different job at 6am.

dogorthopedic.com

What the house needs for a no-good-leg recovery#

For the first week or two after a single-session bilateral, whether osteotomy or FHO, the dog cannot be asked to favour one leg because there is none to favour. The free answer comes first: a rolled bath towel under the belly, held from above, gets a medium dog out to the garden and back on night one and costs nothing. It fails in the ways it always fails: it slides forward on a dog with a deep chest, it needs both of your hands, and it does not clear a male dog's anatomy, which at 6am matters more than it sounds. If the towel is failing, the reason to buy a sling for this recovery rather than any other is a feature nobody explains on the box: a belly sling lifts the pelvis, not a leg. It does not choose a side. In a staged recovery, the "good" hip you are protecting the operated leg with is the other painful hip, and a sling that unloads the pelvis unloads both. In a single-session recovery it is the only support that does not ask the dog to decide which leg to give you.

The downsides stand. It is rear-end only, the chest harness the maker recommends for older dogs is not in the box, and the return window is 10 clean days, which is shorter than either recovery; buy it before surgery day if you are going to buy it, not on night one. It also hides the thing you are watching: a slung dog's gait is your arm's gait, so take it off for the sixty seconds you film him each week. For a staged replacement that will run six months or more from first cut to second recovery, the sling page's own rule sends you to the Help 'Em Up harness instead, and we would rather you bought it direct. One caution that is not ours to settle: a dog with a new hip replacement has luxation precautions that vary by implant and surgeon. Ask before you put anything under his belly, and ask specifically about lifting the rear.

The third outcome, and the date that keeps it honest#

Most staged hip replacement plans end as one hip, and at one hospital's count that is the right ending four times in five. The failure is not stopping at one. The failure is stopping at one without anyone deciding to. "We'll see how he does" is a plan only if it has three parts: a date, a measurement, and a person. The date is the recheck after the first hip has healed, which most surgeons already set. The measurement is the un-operated hip on the day, not the memory of it: can he sit square, does he rise without a shuffle, does the leg extend behind him without a reaction, and has the muscle over that hip kept up with the operated side. Our page on telling whether a limp is actually improving explains why the memory version of that is worthless and the measured version is not. The person is you, because the surgeon will see the dog for twenty minutes and you will see him get off the floor every morning.

If he is comfortable on the day, you have joined the 80%, and the plan is to keep measuring at intervals rather than to stop. If he is not, you are where the 2011 paper found 272 owners: deciding a second time, faster, with one thing you did not have the first time, which is a clear memory of what the operation gave back. Use that.

What to do this week#

• Ask which schedule you were actually offered, and why. For a replacement, the answer will be staged, and the useful follow-up is "what would make you operate the second side, and when will we look." For a pelvic osteotomy, the answer is probably both at once, and the useful follow-up is the surgeon's own bilateral complication experience, because the published series are one centre each.
• Get the estimate to say one hip or two, one session or two, and what the second costs. A quote that does not say is not a quote.
• If your dog has had a bilateral FHO and has gone backwards: a bad few days in the first weeks is soft tissue; scale back briefly and resume. A leg that was in use and is not, or a large dog painful months later, is a call for films of the cut, not for patience. The four-dog CT study is small, but it is the documented reason not to assume the operation settled the question.
• Set the review date for the other hip now, in the calendar, with what you will measure written beside it. The plan that ends at one hip should end there by decision, on a day, and not because nobody looked.
• If the house is about to do a no-good-leg recovery, decide tonight who lifts, with what, and whether the towel is enough for your dog's size. The sling, if you buy it, is bought before the surgery, not after the first night on the kitchen floor.

Two bad hips do not double the decision. They add one: when. The literature is thinner on that than on almost anything else about the hip, and this page has said so wherever it is true. What the literature does say clearly is that the same owners, facing the same decision a second time, waited less. Two hundred and seventy-two of them. The paper does not say why. We have told you what we think.

Sources#

1. Allaith S, Tucker LJ, Innes JF, Arthurs G, Vezzoni A, Morrison S, Onyett J, Stork CK, Witte P, Denny H, Pettitt R, Moores AP, Maddox T, Comerford EJ. "Outcomes and complications reported from a multiuser canine hip replacement registry over a 10-year period." Veterinary Surgery. 2023;52(2):196-208. doi:10.1111/vsu.13885 — 1,852 dogs; 1,329 (72%) unilateral and 523 (28%) bilateral; 2,375 replacements; 85% dysplasia/osteoarthritis; surgeon-reported complications 201/2,375 (8.5%), owner-reported 107/461 (23%), weighted kappa 0.44; no association with weight, age, sex or breed. Abstract read via Europe PMC 29 September 2026.
2. Iowa State University, Lloyd Veterinary Medical Center. "Total Hip Replacement." vetmed.iastate.edu — read 29 September 2026: "Only one hip is operated at first, usually the clinically most effected side"; "Eighty percent of the patients with arthritis in both hips only require one side be operated upon to return them to a satisfactory and comfortable life"; "The decision to operate the second side is made after recovery from the first."
3. Global Veterinary Specialists (William D. Liska). "Hip Dysplasia." globalvetspecialists.org — read 29 September 2026: "The most painful hip is the first to receive a THR if both hips are arthritic and painful and causing lameness"; "Both hips are replaced in over 50% of the dogs that are painful on both sides, but the surgeries are almost always staged about 6 weeks to several months apart."
4. American College of Veterinary Surgeons. "Canine Hip Dysplasia." acvs.org — read 29 September 2026: DPO/TPO "is another option for immature dogs (ideally less than 8–10 months old)." The page describes JPS, DPO/TPO, THR and FHO individually and contains no statement on bilateral, single-session or staged surgery. Verified absent.
5. Austin Veterinary Emergency & Specialty. "What Dog Owners Should Know About Total Hip Replacement." austinvets.com — read 29 September 2026: the majority of dogs with hip dysplasia "are affected in both hips, although one hip is typically worse clinically"; "Usually, these dogs' quality of life can be significantly improved by replacing only the more damaged hip"; "Only about 20 percent of dogs require both hips replaced, and the decision to operate on the second side is typically made after recovery from the first procedure."
6. Lockwood AA, Liska WD. "Duration of clinical signs prior to total hip replacement in dogs." JAVMA. 2011;238(7):905-908. doi:10.2460/javma.238.7.905 — 833 unilateral (334 in 1992–2000, 499 in 2001–2009) and 272 staged bilateral dogs; duration of signs before surgery increased significantly between the two periods; in bilateral dogs, "the interval between surgeries was shorter than the duration of clinical signs before the first THR." Abstract read via Europe PMC 29 September 2026; the mean durations are in the full text, which we did not access, and are not quoted here.
7. Ramezani A, Ghaseminejad Raeini A, Sharafi A, Sheikhvatan M, Mortazavi SMJ, Shafiei SH. "Simultaneous versus staged bilateral total hip arthroplasty: a systematic review and meta-analysis." Journal of Orthopaedic Surgery and Research. 2022;17:392. doi:10.1186/s13018-022-03281-4 — human patients: 29,551 simultaneous vs 74,600 staged; fewer DVT and systemic, local and pulmonary complications, lower blood loss, stay and cost with simultaneous surgery; more pulmonary embolism and periprosthetic fracture. Cited to show the human evidence exists; not applied to dogs.
8. Borostyankoi F, Rooks RL, Kobluk CN, Reed AL, Littledike ET. "Results of single-session bilateral triple pelvic osteotomy with an eight-hole iliac bone plate in dogs: 95 cases (1996-1999)." JAVMA. 2003;222(1):54-59. doi:10.2460/javma.2003.222.54 — mean age 10.8 months, mean weight 35.2 kg, mean surgical time 95 minutes, all but one dog walking unaided by day 4, mean hospitalization 7.5 days, mean iliac healing 8 weeks, 7 of 1,520 screws loosened, no plates, 19 dogs with complications, all minor.
9. Vezzoni A, Boiocchi S, Vezzoni L, Vanelli AB, Bronzo V. "Double pelvic osteotomy for the treatment of hip dysplasia in young dogs." Veterinary and Comparative Orthopaedics and Traumatology. 2010;23(6):444-452. doi:10.3415/VCOT-10-03-0034 — 53 joints in 34 dogs aged 4.5 to 9 months; "the morbidity after unilateral and bilateral DPO was lower than after TPO because elimination of the ischiatic osteotomy allowed for increased stability of the pelvis." Abstract read via Europe PMC 29 September 2026; the abstract does not state whether bilateral cases were done in one session.
10. Papadopoulos G, Tommasini Degna M. "Two cases of dysuria as a complication of single-session bilateral triple pelvic osteotomy." Journal of Small Animal Practice. 2006;47(12):741-743. doi:10.1111/j.1748-5827.2006.00112.x — urethral compression from pelvic canal narrowing in both dogs; relieved by external fixation distracting the acetabular fragments.
11. Kang K, Jang M, Choi KU, Kweon OK, Choi M, Yoon J. "Antegrade and retrograde CT urethrography with virtual urethroscopy in a dog with urethral narrowing after bilateral triple pelvic osteotomy." Veterinary Radiology & Ultrasound. 2021;62(5):E48-E53. doi:10.1111/vru.12799 — 8-month-old castrated male Golden Retriever unable to urinate without catheterisation after single-session bilateral TPO; urethra narrowed near the pubic remnants; normal after corrective surgery.
12. Dudley RM, Wilkens BE. "Urethral obstruction as a complication of staged bilateral triple pelvic osteotomy." Journal of the American Animal Hospital Association. 2004;40(2):162-164. doi:10.5326/0400162 — 5-month-old neutered male Labrador Retriever; medical therapy failed; surgical correction required.
13. Rawson EA, Aronsohn MG, Burk RL. "Simultaneous bilateral femoral head and neck ostectomy for the treatment of canine hip dysplasia." Journal of the American Animal Hospital Association. 2005;41(3):166-170. doi:10.5326/0410166 — 15 dogs, severe bilateral dysplasia; owner survey 6 to 48 months after surgery; all dogs reported to have normal activity and to be pain free; "especially when other surgical options were not indicated or were cost prohibitive." Abstract only.
14. Brasali H, Stewart S, Amato NS. "Clinical perioperative outcomes in 39 cats after single session bilateral femoral head and neck excision." Journal of Feline Medicine and Surgery. 2024;26(9). doi:10.1177/1098612X241275890 — all cats discharged within 48 hours; one major and five minor complications; all but one returned to normal activity. Cats, cited as the only perioperative series of the procedure.
15. Off W, Matis U. "Excision arthroplasty of the hip joint in dogs and cats. Clinical, radiographic, and gait analysis findings from the Department of Surgery, Veterinary Faculty of the Ludwig-Maximilians-University of Munich, Germany." Veterinary and Comparative Orthopaedics and Traumatology. 2010;23(5):297-305 (English translation of the 1997 Tierärztliche Praxis paper). doi:10.1055/s-0037-1617478 — 132 dogs and 51 cats, 1978–1989; 81 (44%) re-examined at a mean of four years, 17 with gait analysis; functional result good 38%, satisfactory 20%, poor 42%; 96% of owners satisfied.
16. Rehnblom E, Gordon-Evans WJ. "Are dogs with hip dysplasia in less pain after total hip replacement than femoral head ostectomy?" Veterinary Evidence. 2022;7(1). doi:10.18849/ve.v7i1.388 — knowledge summary; 12 papers appraised; strength of evidence weak; no study directly comparing pain after THR and bilateral FHO in large juvenile dogs.
17. Ober C, Pestean C, Bel L, Taulescu M, Milgram J, Todor A, Ungur R, Leșu M, Oana L. "Use of clinical and computed tomography findings to assess long-term unsatisfactory outcome after femoral head and neck ostectomy in four large breed dogs." Acta Veterinaria Scandinavica. 2018;60:28. doi:10.1186/s13028-018-0382-8 — hip pain, atrophy, reduced range of motion and chronic lameness; CT showed extensive remodelling, "unacceptable bone-on-bone contact" and, in one case, excessive removal with bone lysis; one revision, no improvement.
18. Fullagar BA, Rajala-Schultz P, Hettlich BF. "Comparison of complication rates of unilateral, staged bilateral, and single-session bilateral surgery for the treatment of bilateral medial patellar luxation in dogs." Canadian Veterinary Journal. 2017;58(1):39-44. Europe PMC MED/28042153 — 93 dogs, 119 stifles; 65 unilateral, 16 staged bilateral, 11 single-session bilateral; complications 28/119 (24%), revision 11 (9%), reluxation 7/119 (6%); no significant association between timing and complications.
19. Brodbelt DC, Blissitt KJ, Hammond RA, Neath PJ, Young LE, Pfeiffer DU, Wood JLN. "The risk of death: the confidential enquiry into perioperative small animal fatalities." Veterinary Anaesthesia and Analgesia. 2008;35(5):365-373. doi:10.1111/j.1467-2995.2008.00397.x — 98,036 dogs across 117 practices; anaesthetic and sedation-related death within 48 hours 0.17% overall (1 in 601) and 0.05% (1 in 1,849) in healthy dogs.