Hip Dysplasia in Dogs: Signs, Treatment, and Why to Ask for a PennHIP Number

Hip dysplasia is one of the most common developmental orthopedic diseases in dogs: across the entire Orthopedic Foundation for Animals registry — 921,046 unique dogs — 15.56% were dysplastic, with working breeds carrying nearly twice the odds of hounds.^[1] The good news is that most dogs do not need surgery. This guide walks through what's actually happening in the joint, what the evidence supports at each stage, and the equipment that makes daily life easier — with the honest ranking of which interventions are actually proven and which are mostly sold.

What's actually happening in the joint#

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Hip dysplasia starts as joint laxity in puppyhood: the ball of the femur does not sit tightly in the socket of the pelvis. Over months and years, the abnormal motion causes microscopic damage to the cartilage, which the body repairs with scar tissue and bone — i.e. osteoarthritis.

The timeline here is better documented than most owners are told, because one group of 48 Labradors was radiographed yearly from puppyhood until natural death. Two findings from that cohort are worth carrying around. First, the looseness shows up early and then stops changing: subluxation visible on a hip-extended radiograph appeared by two years of age and not afterwards.^[2] Second, the arthritis shows up much later, and how late depends on how you feed the dog: a circumferential femoral head osteophyte — one of the earliest visible signs of the arthritis to come — appeared at a median age of 9 years in the diet-restricted dogs and 3 years in the ones fed freely.^[3]

That gap — three years against nine, in dogs with the same genetics, on the same food, differing only in portion size — is the most important number on this page. The looseness is your dog's inheritance. The arthritis timetable is substantially yours.

Pain comes from two sources: the ongoing cartilage damage and the soft-tissue inflammation around an unstable joint. This matters because it tells you what the treatment options actually do — they target one or both of those mechanisms.

Diagnosis#

The definitive test is a hip radiograph (X-ray) read by a veterinary radiologist. Two grading systems are common in the U.S., and they do not measure the same thing — which is the part almost nobody explains.

• OFA (Orthopedic Foundation for Animals) — seven categories: Excellent, Good, Fair (all within normal limits), Borderline, then Mild, Moderate or Severe. It is a subjective read of a hip-extended radiograph. OFA offers preliminary screening for dogs between 4 and 23 months of age.^[4]
• PennHIP — measures joint laxity as a number, the distraction index, from a distraction radiograph taken under sedation.

Here is why the distinction matters to you rather than to a breeder. When 439 dogs were screened both ways, 80% of the dogs OFA rated fair, good or excellent had a distraction index of 0.30 or higher — the threshold above which dogs are considered susceptible to osteoarthritis. Among dogs graded excellent, 52% were above it.^[5] A hip-extended film graded normal is not a clean bill of health; it is one instrument, read subjectively, missing a lot of laxity.

The lifetime Labrador cohort makes the same point from the other end: 55% of dogs graded normal at two years old were radiographically dysplastic by the end of life, and 92% of those "normal" dogs had osteoarthritis on post-mortem examination.^[2]

The honest caveat in the other direction. A high distraction index does not sentence a dog to arthritis. In 399 Pembroke Welsh Corgis, every single dog had a distraction index above 0.30, with a mean of 0.66 — and only 6.8% had osteoarthritis.^[6] Laxity is a risk factor, breed-dependent, not a diagnosis. If a number frightens you, that Corgi study is the reason to ask your vet what it means for your breed before you spiral.

One more thing worth knowing if you are reading breed statistics anywhere: published prevalence figures from voluntary registries are biased downward, because owners of dogs with bad films often decline to submit them. When researchers screened 200 clinically normal Golden Retrievers and 140 Rottweilers themselves rather than waiting for submissions, they documented exactly that submission bias.^[7] The real rates in high-risk breeds are higher than the registry says.

If you have a high-risk breed (Labrador, Golden, Shepherd, Pyrenees, Saint Bernard, Newfoundland, Bernese), screen — and ask about distraction-index measurement rather than accepting a hip-extended view as the whole answer.

The medical-management toolkit#

Most dogs with mild-to-moderate dysplasia never need surgery. The pillars of medical management:

1. Weight management#

This is the intervention with the best evidence behind it, and the numbers are more encouraging than "get the weight off" suggests, because the threshold is low.

In an open trial of 14 obese dogs with radiographically confirmed osteoarthritis fed a restricted-calorie diet for 16 weeks, lameness scores fell significantly from 6.10% body-weight loss onward, with kinetic gait analysis confirming the improvement from 8.85% onward.^[8] For an 80 lb retriever, 6.10% is under 5 lb. That is one biscuit a day for a season, not a transformation.

Two caveats we should raise ourselves: 14 dogs is a small trial, and it had no control group, so some of the improvement could be the passage of time or the owners' hope. The reason to believe it anyway is that a completely different study design points the same way. In the Purina lifetime study, 48 Labradors were paired with a littermate and one of each pair was fed 25% less for life. At eight years, radiographic osteoarthritis affecting multiple joints was significantly more common in the freely-fed dogs, with hip lesions in 15 of 22 control dogs.^[9] The same cohort, followed to death, showed a significantly longer median life span in the food-restricted dogs and later onset of chronic disease.^[10] The hip-specific analysis of that cohort is published separately.^[11]

And the effect is visible at population scale. In 114,568 young adult dogs of 72 breeds screened by the Swedish Kennel Club, higher body weight within a breed was associated with a more severe hip dysplasia grade, significantly so in 13 of the 21 breeds analysed.^[12]

Body condition score 4–5 on the standard 9-point scale. Ribs palpable but not visible. Visible waist from above.

2. Joint supplementation — with the evidence stated plainly#

This section used to tell you to start here. It was wrong, and correcting it costs us money, so read the correction rather than our old sentence.

Glucosamine and chondroitin have now failed twice under objective measurement. In a blinded, placebo-controlled trial of 75 dogs with hip osteoarthritis measured on a force plate, the glucosamine and chondroitin arm did not separate from placebo at four or six weeks, while green-lipped mussel lipid extracts and carprofen both did.^[13] An independent group at a different institution ran 30 dogs against 30 placebo dogs for 97 days with continuous activity monitors and found no difference in daily activity counts — while owner-reported pain scores improved equally in both arms.^[14]

That last clause is the whole problem with this category. The same research group measured how often owners judge their own dog's lameness to have improved when the dog is on a placebo, with a force plate running alongside them: 39.7% of the time.^[15] Veterinarians examining the same dogs did it 43–45% of the time. Nobody is lying. You are reading a dog you love and hoping.

The fair defences, which we should raise because they are real. The force-plate trial had 15 dogs per arm and was powered to detect the mussel-extract effect, not to exclude a smaller glucosamine one. It ran roughly a maintenance dose for all six weeks — nobody has run the trial at the loading dose the labels prescribe. And in that trial the subjective orthopedic scores did not move in any group, including the carprofen group the force plate showed working.

So: a joint supplement is a reasonable thing to try, cheap relative to everything else here, and safe. It is not the foundation of the plan, and if you have limited money and attention this month, weight and omega-3 come first.

If you do try one, give it 6–8 weeks before judging — and know that the return window on most of these is shorter than the loading period the label itself prescribes, so check that before you buy rather than after.

3. Omega-3 fatty acids#

Better evidence than glucosamine, and it is worth knowing exactly how much better.

Three randomised trials in the same programme. In 38 dogs measured by force plate, mean peak vertical force improved 5.6% in the fish-oil group against 0.4% in controls at 90 days, with 82% of the supplemented dogs improving against 38% of controls.^[16] In a larger multicentre trial, 127 dogs across 18 private practices were fed a high-omega-3 food for six months.^[17] And in 131 dogs across 33 hospitals, all standardised onto carprofen first, the omega-3 group's carprofen dosage could be reduced relative to controls.^[18]

The caveat you will not find in supplement marketing: all three of those trials were run on a therapeutic food by the company that makes it, and the authors include its employees. That is not a reason to dismiss them — they are randomised and one used a force plate, which is the hard instrument — but it is a reason to weigh them as industry-funded. Dose by weight, and ask your vet, because fish oil at high doses affects clotting and interacts with other medications.

4. Low-impact exercise#

The instinct to "let the dog rest" is wrong, and there is a measurement that shows how fast rest costs you. In the placebo arm of a 100-dog trial of dogs recovering from knee surgery, thigh circumference fell 1.21 cm in the operated leg and 2.04 cm in the un-operated one over the first eight weeks of restricted activity.^[19] The leg that had nothing wrong with it lost more muscle than the leg that had surgery. That is what enforced stillness does to a dog, and it is why "rest him" is the wrong instinct for a chronic hip.

The right answer is consistent low-impact activity: leashed walks on level ground (avoid stairs), swimming if available, gentle play. No fetch, no off-leash high-speed turns. Our how much walking an arthritic dog needs guide has the specifics, and muscle wasting in one back leg shows you how to measure the loss at home with a tape.

5. Orthopedic bedding#

A lying dog does not spread its weight evenly. When pressure was mapped across four support surfaces, the recurrent pressure-risk points were the shoulder joint, the greater trochanter of the hip, and the thirteenth rib — and the thinnest dogs, with least muscle padding those points, produced the highest peak pressures on every surface tested.^[20] The greater trochanter is the bony point of the hip. A dysplastic, muscle-wasted senior is precisely the dog that study describes.

Now the part we previously overstated. This page used to tell you the Big Barker was "the only bed with a published canine clinical trial showing measurable joint-score improvement." The study is real. That sentence oversold it, and the document says so itself. Its own Study Design section reads: "This clinical trial was a single center, open-label, proof of concept study." Forty dogs over three years old and over seventy pounds, osteoarthritis confirmed by a radiologist at Penn's Ryan Small Animal Hospital, 38 days enrolled with day 28 the primary endpoint — no control group, no blinding, and the assessment tools "were completed by the owners weekly."^[21] It has not been published in a peer-reviewed journal.

Set that design against the 39.7% caregiver placebo rate measured in this exact population^[15] and an unblinded owner-scored trial cannot separate the foam from the hope.

There is one more detail in that report worth a paragraph, because it is checkable in a single click and nobody quotes it. The Data Summary sets its own significance level at α = 0.02. It then states that "the remainder of the statistical tests did not result in rejections of the null hypotheses" — with one exception, Pacing, reported at 83% improvement with a z-statistic of 1.999 and a p-value of 0.0456, "which is statistically significant at the α = 0.05 significance level."^[21] That is the report moving its own goalposts, in its own words, for one result out of many.

None of this means the bed does nothing. Seven inches of foam under a 90 lb dog is a physical fact, and so is a ten-year no-flatten warranty. Buy it for those. Do not buy it for the percentages.

Before you spend anything: press your existing bed hard with your fist where the hip lands. If your knuckles reach the floor, so does the hip — and if they don't, you don't need a new bed this month.

When to consider surgery#

Surgery is on the table when:

1. Pain is not controlled with medical management.
2. Quality of life is meaningfully impaired (won't walk, can't navigate the house).
3. Your dog is young (under 8) and the long-term trajectory is bad.

Three procedures are common:

• FHO (femoral head ostectomy). Removes the femoral head; the body forms a fibrous "false joint." Less expensive than THR and widely available. The largest long-term series — 132 dogs and 51 cats, re-examined an average of four years later — rated function good in 38%, satisfactory in 20%, and poor in 42%, while 96% of owners were satisfied. Gait analysis in that series found the pain relief came at the cost of functional deficits in small breeds as well as large ones, deficits that simply were not visible to the eye at speed.^[22] We used to write that FHO outcomes are "best in smaller dogs." That series does not support it. Our FHO surgery recovery timeline covers the recovery, which is unlike any other orthopedic surgery — controlled movement from the first days rather than weeks of crate rest.
• Total hip replacement (THR). Prosthetic, and the best mechanical result available for a large dog. We have removed the "95%+ success rate" this page used to carry, because we could not find a source for it. What is published is complication data: in 255 consecutive cementless procedures, stem-related complications ran 8.6% intraoperatively and 2% early postoperatively,^[23] and in a separate series of 177 procedures the overall intra- and postoperative complication rate was 13.6%.^[24] Most dogs do very well. "Most" is the honest word, not "95%."
• TPO / DPO (triple or double pelvic osteotomy). Reposition the pelvis to correct underlying laxity, in young dogs without significant arthritis yet. A related early procedure, juvenile pubic symphysiodesis, has been compared against conservative management in 217 puppies assessed at 14–22 weeks: 43.2% of the treated puppies showed regression or lack of progression of dysplasia.^[25] The window for all of these closes early, which is the practical argument for screening a high-risk puppy rather than waiting.

Your surgeon will guide the choice. We recommend a board-certified surgeon (DACVS) for any of these, and our list of questions to ask a veterinary orthopedic surgeon is written for exactly this appointment.

The mobility tools that help every dysplasia case#

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A vehicle ramp ends the worst single load on hip joints in daily life: the SUV jump-down. Dogs that have never used a ramp need a few sessions of leashed practice; once they get it they prefer the ramp.

For severe cases or post-surgical recovery, a two-piece harness with a hip handle is what saves your back and your dog's dignity on the ten assists a day nobody warns you about. We have removed the line claiming rehab vets "recommend it by name" — we have no survey or source for that, and it was doing sales work rather than information work. Buy it for the hip handle and the load spread; don't substitute a converted seatbelt strap, which concentrates force exactly where a dysplastic dog cannot take it.

If your dog is splaying out on hardwood, ToeGrips restore traction immediately. The cheapest, fastest improvement to daily comfort for an arthritic dog living with slick floors.

What we'd skip#

• "Hip and joint" treats with sub-therapeutic doses. Read the active ingredient mg per chew. The force-plate trial above ran glucosamine at roughly 30 mg per kg of body weight per day;^[13] if the chew has 100 mg of glucosamine, a 32 kg dog is getting about a tenth of that. Our dosing by weight page does the arithmetic per brand.
• CBD as primary management. Don't replace NSAIDs with it. We have not done the citation work on canine CBD to a standard we would publish, so treat this line as our opinion rather than a sourced finding.
• Massage chairs / vibration platforms / "stim" devices. We found no canine clinical evidence. Save the money.
• Cold laser / PEMF at home. We are not able to point you at consumer-grade home-device evidence in dogs. Clinic-administered versions are a question for your vet, not for us.

When to escalate#

Call your vet (don't wait for the next routine appointment) if:

• Sudden non-weight-bearing lameness in either rear leg.
• Dog cannot rise from a down position despite assistance.
• Significant decrease in appetite combined with pain.
• Crying out when standing or moving.

Sudden severe lameness in a dysplastic dog can indicate a cruciate ligament rupture, an acute disc problem, or a fracture — and telling a limp apart from weakness is the first fork in that road, which our limping vs weakness guide walks through.

A claim we have removed from this page. We used to write that "the contralateral cruciate goes within 12 months in many dysplastic dogs because of compensation patterns." That conflated two different populations and we could not source it. The contralateral-rupture figures in the literature describe dogs that have already ruptured one cruciate, not dogs with hip dysplasia: in 831 medium-to-large dogs aged eight or older at their first cruciate rupture, 19.1% ruptured the other side, a median of 12.9 months later.^[26] In a separate longitudinal study of 380 dogs, median survival of the second cruciate was 947 days.^[27] We have no data at all on second-cruciate risk specifically in dysplastic dogs.

The bottom line#

Most dogs with hip dysplasia live full lives on medical management. But the interventions are not equal, and this page used to present them as if they were. Ranked by the strength of the evidence behind them, not by what is easiest to sell:

If your dog has just been diagnosed: don't panic, and don't start by buying things. Weigh him this week. Ask your vet for a target and a body condition score. Those two acts have better evidence behind them than everything else on this page combined, and they cost nothing.

The dog you've had for ten years can still have ten more good ones. What shortens that is not the diagnosis — it is the eighteen months between when the joint started hurting and when somebody noticed. The delay is the injury.

Sources#

Every source below was opened and read on 14 August 2026. Where a claim on this page previously had no source and none could be found, the claim was cut and the removal is stated in the text rather than hidden.

1. Loder RT, Todhunter RJ. "The Demographics of Canine Hip Dysplasia in the United States and Canada." Journal of Veterinary Medicine. 2017;2017:5723476. doi:10.1155/2017/5723476 (PMID 28386583) — entire OFA hip registry, 921,046 unique records; overall CHD prevalence 15.56%; odds higher in females (OR 1.05), spring (1.14) and winter (1.13) births, southern latitudes (2.12); AKC working group OR 1.882 vs hounds; FCI pinscher/molossoid group OR 4.168.
2. Smith GK, Lawler DF, Biery DN, et al. "Chronology of hip dysplasia development in a cohort of 48 Labrador retrievers followed for life." Veterinary Surgery. 2012;41(1):20-33. doi:10.1111/j.1532-950X.2011.00935.x (PMID 23253036) — subluxation on hip-extended radiographs appeared by 2 years and not thereafter; 55% of dogs scored "normal" at 2 years were radiographically dysplastic by end of life; 92% of those had histopathologic osteoarthritis; distraction index predicted all 48 dogs susceptible.
3. Szabo SD, Biery DN, Lawler DF, et al. "Evaluation of a circumferential femoral head osteophyte as an early indicator of osteoarthritis characteristic of canine hip dysplasia in dogs." JAVMA. 2007;231(6):889-892. doi:10.2460/javma.231.6.889 (PMID 17867972) — CFHO in 41/48 dogs at median 5.4 years; median 9 years in diet-restricted vs 3 years in control-fed dogs.
4. Orthopedic Foundation for Animals. "Hip Dysplasia." ofa.org — read 14 August 2026: grades are "Excellent, Good, Fair (all within Normal limits), Borderline, and then Mild, Moderate, or Severe"; "For dogs that are between 4 months and 23 months of age, preliminary screenings are available."
5. Powers MY, Karbe GT, Gregor TP, et al. "Evaluation of the relationship between Orthopedic Foundation for Animals' hip joint scores and PennHIP distraction index values in dogs." JAVMA. 2010;237(5):532-541. doi:10.2460/javma.237.5.532 (PMID 20807130) — 439 dogs screened both ways; 52% of OFA-excellent, 82% of OFA-good and 94% of OFA-fair hips had a distraction index ≥0.30; 80% of all fair-to-excellent hips were above the threshold.
6. Karbe GT, Biery DN, Gregor TP, Giger U, Smith GK. "Radiographic hip joint phenotype of the Pembroke Welsh Corgi." Veterinary Surgery. 2012;41(1):34-41. doi:10.1111/j.1532-950X.2011.00938.x (PMID 23253037) — 399 Corgis, all with distraction index >0.30 (mean 0.66), yet only 6.8% had osteoarthritis.
7. Paster ER, LaFond E, Biery DN, et al. "Estimates of prevalence of hip dysplasia in Golden Retrievers and Rottweilers and the influence of bias on published prevalence figures." JAVMA. 2005;226(3):387-392. doi:10.2460/javma.2005.226.387 (PMID 15702688) — 200 clinically normal Goldens and 140 Rottweilers screened prospectively; OFA submission rate of a separate group of 93 dogs measured directly to quantify submission bias.
8. Marshall WG, Hazewinkel HA, Mullen D, De Meyer G, Baert K, Carmichael S. "The effect of weight loss on lameness in obese dogs with osteoarthritis." Veterinary Research Communications. 2010;34(3):241-253. doi:10.1007/s11259-010-9348-7 (PMID 20237844) — 14 obese client-owned dogs, open prospective trial, 16 weeks; significant lameness reduction from 6.10% body-weight loss onward, kinetic gait analysis supporting from 8.85%. No control group.
9. Kealy RD, Lawler DF, Ballam JM, et al. "Evaluation of the effect of limited food consumption on radiographic evidence of osteoarthritis in dogs." JAVMA. 2000;217(11):1678-1680. doi:10.2460/javma.2000.217.1678 (PMID 11110459) — 48 Labradors paired by sex and weight within litters, randomised to control-fed or 25% limit-fed; at 8 years hip lesions in 15/22 control-fed dogs, multi-joint osteoarthritis significantly more common in control-fed group.
10. Kealy RD, Lawler DF, Ballam JM, et al. "Effects of diet restriction on life span and age-related changes in dogs." JAVMA. 2002;220(9):1315-1320. doi:10.2460/javma.2002.220.1315 (PMID 11991408) — same cohort followed to death; median life span significantly longer in food-restricted dogs, onset of chronic disease generally delayed.
11. Smith GK, Paster ER, Powers MY, et al. "Lifelong diet restriction and radiographic evidence of osteoarthritis of the hip joint in dogs." JAVMA. 2006;229(5):690-693. doi:10.2460/javma.229.5.690 (PMID 16948575) — the hip-specific analysis of the same 48-dog paired-feeding cohort, radiographs scored by a board-certified radiologist blinded to group.
12. Andersson L, Engdahl K, Ringmark S, et al. "Association between body weight and hip dysplasia screening results in young adult dogs of different breeds in Sweden." Scientific Reports. 2026;16(1):17144. doi:10.1038/s41598-026-55816-y (PMID 42236888) — 114,568 young adult dogs, 72 breeds, Swedish Kennel Club screening 2007–2016 without preselection; higher within-breed body weight associated with more severe HD grade, significant in 13 of 21 breeds analysed.
13. Kampa N, Kaenkangploo D, Jitpean S, et al. "Study of the effectiveness of glucosamine and chondroitin sulfate, marine based fatty acid compounds (PCSO-524 and EAB-277), and carprofen for the treatment of dogs with hip osteoarthritis: A prospective, block-randomized, double-blinded, placebo-controlled clinical trial." Frontiers in Veterinary Science. 2023;10:1033188. doi:10.3389/fvets.2023.1033188 (PMID 36816197) — 75 dogs, five arms of 15. At week 4 the glucosamine/chondroitin group's change in peak vertical force was −0.05 ± 6.34 against placebo 0.08 ± 1.90, while PCSO-524 (3.90), EAB-277 (4.17) and carprofen (3.08) were significant and significantly greater than both. Subjective orthopaedic scores did not change in any group, including carprofen. Funded by Pharmalink International Ltd, which owns the EAB-277 and Antinol trademarks; the senior author discloses paid consultancy for VetzPetz Asia. Dosing ~30 mg/kg/day.
14. Scott RM, Evans R, Conzemius MG. "Efficacy of an oral nutraceutical for the treatment of canine osteoarthritis. A double-blind, randomized, placebo-controlled prospective clinical trial." VCOT. 2017;30(5):318-323. doi:10.3415/VCOT-17-02-0020 (PMID 28763523) — 30 dogs vs 30 placebo, 97 days, continuous activity monitors; no difference in daily activity counts between groups; owner-completed Canine Brief Pain Inventory improved in both.
15. Conzemius MG, Evans RB. "Caregiver placebo effect for dogs with lameness from osteoarthritis." JAVMA. 2012;241(10):1314-1319. doi:10.2460/javma.241.10.1314 (PMID 23113523) — placebo arm of a prospective, randomised, double-blinded, placebo-controlled multicentre trial, 58 dogs, force platform running alongside; owners judged lameness improved 39.7% of the time, veterinarians 43.1–44.8%.
16. Roush JK, Cross AR, Renberg WC, et al. "Evaluation of the effects of dietary supplementation with fish oil omega-3 fatty acids on weight bearing in dogs with osteoarthritis." JAVMA. 2010;236(1):67-73. doi:10.2460/javma.236.1.67 (PMID 20043801) — 38 client-owned dogs, randomised and blinded, force-plate analysis; mean peak vertical force change day 0 to 90 of 5.6% (test food) vs 0.4% (control); improvement in 82% vs 38% of dogs.
17. Roush JK, Dodd CE, Fritsch DA, et al. "Multicenter veterinary practice assessment of the effects of omega-3 fatty acids on osteoarthritis in dogs." JAVMA. 2010;236(1):59-66. doi:10.2460/javma.236.1.59 (PMID 20043800) — 127 client-owned dogs, 18 private practices, randomised double-blinded controlled, 6 months.
18. Fritsch DA, Allen TA, Dodd CE, et al. "A multicenter study of the effect of dietary supplementation with fish oil omega-3 fatty acids on carprofen dosage in dogs with osteoarthritis." JAVMA. 2010;236(5):535-539. doi:10.2460/javma.236.5.535 (PMID 20187817) — 131 client-owned dogs, 33 hospitals, all standardised to ~4.4 mg/kg/day carprofen before randomisation. Studies 16–18 evaluate a commercial therapeutic food and include employees of its manufacturer among the authors.
19. White DA, Harkin KR, Roush JK, Renberg WC, Biller D. "Fortetropin inhibits disuse muscle atrophy in dogs after tibial plateau leveling osteotomy." PLoS ONE. 2020;15(4):e0231306. doi:10.1371/journal.pone.0231306 — 100 client-owned dogs, prospective randomised double-blinded placebo-controlled; placebo group lost 1.21 cm of thigh circumference in the operated limb and 2.04 cm in the unaffected limb from week 0 to 8. Funded by the manufacturer, MYOS RENS Technology Inc. The paper does not report a statistical test of the difference between the two limbs.
20. Caraty J, De Vreught L, Cachon T, et al. "Comparison of the different supports used in veterinary medicine for pressure sore prevention." Journal of Small Animal Practice. 2019;60(10):623-630. doi:10.1111/jsap.13061 (PMID 31364781) — cadaver dogs of differing body condition scores in lateral recumbency across four supports, pressures mapped over 4 hours; recurrent risk zones at the scapulohumeral articulation, greater trochanter and thirteenth rib.
21. Mengel GA (principal investigator). A Pilot Study to Evaluate the Big Barker Therapeutic Mattress in Dogs with Osteoarthritis — Final Study Report Summary. University of Pennsylvania School of Veterinary Medicine, Veterinary Clinical Investigations Center. Full report PDF, read in full 14 August 2026. Study Design section verbatim: "This clinical trial was a single center, open-label, proof of concept study." Dogs >3 years and >70 lb, osteoarthritis confirmed by a veterinary radiologist at the Ryan Small Animal Hospital; enrolled 38 days (10 days prior to randomization, 28 days following), day 28 the primary endpoint; assessment tools (COI, CBPI, CSAS, GAC, LOI) "were completed by the owners weekly." Results reported for 40 dogs in an "open label single arm study." Improvements to mean score: Pain 19.9%, Pain Severity 21.6%, Pain Interference 14.3%, Joint Stiffness 12.5%, Joint Function 17.6%, Gait 9.6%, Quality of Life 15.1%. Accelerometer: 50% of dogs had at least a 13% decrease in night-time activity, 25% at least 33%. Significance level set at α = 0.02; "The remainder of the statistical tests did not result in rejections of the null hypotheses," with the exception of Pacing (83% improvement, z = 1.999, p = 0.0456) reported as significant "at the α = 0.05 significance level." Statistics performed by an independent statistician unaffiliated with Big Barker or the University of Pennsylvania. Not a peer-reviewed journal publication.
22. Off W, Matis U. "Excision arthroplasty of the hip joint in dogs and cats." VCOT. 2010;23(5):297-305. doi:10.1055/s-0037-1617478 (PMID 20945541) — 132 dogs and 51 cats operated 1978–1989 at Ludwig-Maximilians University, Munich; 81 (44%) re-examined at an average of four years, gait analysis in 17. Function good 38%, satisfactory 20%, poor 42%; 96% of owners satisfied; kinetic and kinematic deficits in small as well as large breeds, not visible during rapid movement.
23. Kokkinos P, Parsons K, Belch A, Barthelemy N. "The influence of age at total hip replacement on perioperative complications associated with a press-fit cementless stem with lateral bolt in dogs." Veterinary Surgery. 2025;54(4):581-593. doi:10.1111/vsu.14203 (PMID 39815446) — 197 client-owned dogs, 255 THRs; intraoperative stem complication rate 8.6%, early postoperative 2%.
24. Low D, Treharne R, Rutherford S. "Subsidence of the BFX standard stem after canine total hip replacement: A case series of 177 consecutive procedures." Veterinary Surgery. 2026;55(6):763-770. doi:10.1111/vsu.70084 (PMID 41660743) — 177 procedures in 145 dogs; 24/177 (13.6%) intra- and postoperative complications, 11/177 (6.2%) stem-related.
25. Vezzoni A, Dravelli G, Vezzoni L, et al. "Comparison of conservative management and juvenile pubic symphysiodesis in the early treatment of canine hip dysplasia." VCOT. 2008;21(3):267-279. doi:10.1055/s-0037-1617372 (PMID 18536855) — 217 puppies assessed at 14–22 weeks completed the study, 81 treated with JPS and 76 managed conservatively plus 60 normal-hip controls; 43.2% of the JPS group showed regression or lack of progression of dysplasia.
26. Murphy CL, Niles J, Radasch RM. "The Prevalence and Risk Factors of Contralateral Cranial Cruciate Ligament Rupture in Medium-to-Large (≥15kg) Breed Dogs 8 Years of Age or Older." VCOT. 2024;37(1):8-12. doi:10.1055/s-0043-1771350 (PMID 37487534) — 831 client-owned dogs, median follow-up 112.7 months; 19.1% (159/831, 95% CI 16.6–22.0%) ruptured the contralateral cruciate at a median of 12.9 months.
27. Muir P, Schwartz Z, Malek S, et al. "Contralateral cruciate survival in dogs with unilateral non-contact cranial cruciate ligament rupture." PLoS ONE. 2011;6(10):e25331. doi:10.1371/journal.pone.0025331 (PMID 21998650) — baseline population of 380 dogs; median contralateral cruciate survival 947 days; increasing tibial plateau angle shortened survival, increasing age at diagnosis lengthened it.
28. Berg JA, Sævik BK, Trangerud C, Madsen P, Lingaas F. "Genetic analyses of lumbosacral transitional vertebra and hip dysplasia in nine dog breeds in Norway." Acta Veterinaria Scandinavica. 2025;67(1):25. doi:10.1186/s13028-025-00810-z (PMID 40420218) — heritability estimates for canine hip dysplasia 0.254–0.580 across nine breeds. Cited in the FAQ.
29. Leighton EA, Holle D, Biery DN, et al. "Genetic improvement of hip-extended scores in 3 breeds of guide dogs using estimated breeding values." PLoS ONE. 2019;14(2):e0212544. doi:10.1371/journal.pone.0212544 (PMID 30794614) — 5,201 German Shepherd Dogs, 4,987 Labradors and 2,308 Golden Retrievers; heritability of the hip-extended score 0.76, 0.72 and 0.41, and of distraction index 0.60, 0.66 and 0.59. Cited in the FAQ.

This article is educational and does not replace veterinary advice. Diagnosis, medication and surgical decisions for your dog belong to your veterinarian or a board-certified veterinary surgeon. If your dog is suddenly non-weight-bearing, cannot rise, or is crying out, that is a same-day call, not a reading assignment.