Study analysis · Veterinary journal · 2007
Your dog's arthritis supplement might actually work—but only if you wait 70 days, and the study behind it didn't even include a placebo group.
Dogs with arthritis given a glucosamine/chondroitin supplement got significantly better after 70 days, but the improvement appeared much later than with a standard painkiller, and the study didn't use a dummy pill to prove the effect was real.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
In simple terms
Think of a study where sick dogs got a supplement and other sick dogs got a known pain medicine. Both groups got better, but there was no group that got nothing. So maybe the dogs would have gotten better anyway, and we can't be sure the supplement actually did anything. It's like taking two kinds of candy and feeling happier, but not checking if a kid who got no candy also felt happier.
What’s the bottom line?
Dogs with arthritis were given either a supplement called glucosamine/chondroitin or a standard pain medicine (carprofen). Vets checked the dogs at different times to see if they were in less pain and walking better.
How strong is this study?
The study was done pretty carefully—dogs were randomly put into two groups, and the doctors didn't know which dog got which treatment. That helps prevent cheating or bias. But there were not very many dogs, and the improvement was judged just by looking, not with a machine. Also, because there wasn't a fake treatment group, we can't be 100% sure the supplement is what made the dogs better.
0 / 100
- COI disclosureconflicts of interest not disclosed
- Data availabilitydata not shared
- Code availabilitycode not shared
79 / 100
- Randomization+20/20
- Blinding+15/15
- Control group+15/15
- Sample size (n=35)+3.2/20
- Follow-up+10/10
100 / 100
23 / 100
- P-values+15/15
- Effect sizeno effect size reported
- Confidence intervalsno confidence intervals
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 516 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
This design cannot establish causation — the findings describe an association, not a cause. Although this is an RCT, it uses a positive control (carprofen) rather than a placebo. Without a placebo/no-treatment group, the observed improvements in dogs receiving glucosamine/chondroitin sulfate cannot be causally attributed to the treatment, as they might be due to natural disease progression, regression to the mean, or placebo effects. The design can only compare the supplement to an active drug, and no statistical between-group differences were reported.
Major COI
Major conflicts that significantly reduce study credibility
The study was funded by VetPlus Ltd., a company that likely manufactures the glucosamine/chondroitin product being tested. Although no explicit conflict of interest section is present, the funding constitutes a major conflict as the funder has a commercial interest in the outcome.
Funders
Conflict Details
VetPlus Ltd.: Received financial support for the study
BSAVA Petsavers: Funding for residency
Independent Analysis Safeguards
- Randomized double-blind design
- Positive-controlled trial
- Multi-centre trial
- Ethics committee approval and licensing
Funding from VetPlus Ltd., a company that likely manufactures the test product, presents a major conflict of interest. No conflict of interest declaration is visible in the provided sections. BSAVA Petsavers also funded an author's residency but without apparent industry connection. The study uses positive control (carprofen) and subjective outcome measures.
Key takeaways
- 01
After 70 days, dogs on the supplement were doing significantly better (P<0.001) in pain, weight-bearing, and overall condition.
- 02
Improvement was slower than with carprofen (day 70 vs day 42).
- 03
Two dogs on the supplement had side effects and were taken out of the study.
- 04
The supplement appears to help dogs with arthritis, but it takes longer to work than a standard NSAID.
- 05
Since there was no dummy pill group, we cannot be 100% sure the improvement was not partly due to natural changes or owner expectations.
Surprising findings
- Dogs on the supplement improved significantly by day 70 even without a placebo group, but the benefit took 28 days longer to appear than in dogs on carprofen.Many people assume nutraceuticals either work quickly or not at all. Here, the supplement produced measurable improvements, just slowly.
- Two adverse drug reactions occurred in the glucosamine/chondroitin group—not in the NSAID group, which is usually considered the riskier treatment.NSAIDs are often blamed for side effects, while supplements are assumed safe. This study reminds us that 'natural' doesn't always mean harmless.
- Despite having no placebo control, the study still found statistically significant improvements across three independent outcome measures (pain, weight-bearing, severity).A positive-controlled design makes a causal claim weaker, yet the consistent improvements suggest a real effect—though not definitive.
Practical takeaways
If you try a glucosamine/chondroitin supplement for your dog's arthritis, commit to at least 70 days (10 weeks) before judging whether it works, since benefits were not significant before that point.
The study had no placebo control, so the improvement might not be caused by the supplement. Always work with your veterinarian.
medium confidenceFor quicker relief in an arthritic dog, consider a veterinary-prescribed NSAID like carprofen—it showed significant improvement by day 42, much faster than the supplement.
NSAIDs have their own risk of side effects, including gastrointestinal issues. Use under veterinary supervision.
medium confidenceAsk your veterinarian whether objective assessments like force plate gait analysis are available, as subjective evaluations can be biased and harder to interpret.
Force plate analysis is not widely available in general practice and may not be feasible for every dog.
medium confidenceWatch for side effects when starting any joint supplement: in this study, 2 out of 42 dogs (about 5%) were withdrawn due to adverse drug reactions in the Glu/CS group.
The exact side effects were not described in the abstract, and the sample size was small, so the true rate is uncertain.
low confidenceWhy this study matters
The Good News: Supplement Improved Pain and Mobility
In a randomized, double-blind, positive-controlled trial, 35 dogs with hip or elbow osteoarthritis were treated with oral glucosamine hydrochloride and chondroitin sulfate (Glu/CS) or the NSAID carprofen. By day 70, dogs on the supplement showed statistically significant improvements in veterinarian-rated pain, weight-bearing, and overall severity scores (P<0.001).
Pet owners are desperate for drug-free ways to ease their dog's arthritis pain, and this study offers hope—though with important caveats.
The Elephant in the Room: No Placebo Group
The trial used carprofen as a 'positive control' rather than a placebo, meaning all dogs received an active treatment. Without a dummy-pill group, improvements in the supplement group could be partly due to natural disease fluctuation, owner expectations, or veterinarian bias.
This is the flaw that prevents us from confidently saying 'glucosamine works'—yet supplement companies often cite this study without mentioning it.
Wait 70 Days—Not 14 or 42
Significant improvement in the Glu/CS group first appeared on day 70, whereas carprofen showed significant benefit by day 42. The authors explicitly recommend that future trials monitor dogs for a minimum of 70 days because earlier endpoints can miss the effect.
Most owners stop giving joint supplements after a few weeks if they don't see results. This study shows the benefit may take 10 weeks to emerge.
Side Effects? Yes, Two Dogs Were Withdrawn
Out of 42 dogs enrolled, two dogs in the Glu/CS group were withdrawn due to adverse drug reactions. Another dog in that group required surgery, and one was given an NSAID between day 70 and 98. The supplement is not automatically risk-free.
Supplements are often seen as harmless, but this study shows they can cause side effects in some dogs—something owners should discuss with their vet.
Want the whole report?
Detailed mode opens the full scientific breakdown — every score component, the methodology, conflicts of interest, the evidence analysis behind each claim, and the raw study data.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Dogs with arthritis were given either a supplement called glucosamine/chondroitin or a standard pain medicine (carprofen). Vets checked the dogs at different times to see if they were in less pain and walking better.
Research results
After 70 days, dogs on the supplement were doing significantly better (P<0.001) in pain, weight-bearing, and overall condition. Improvement was slower than with carprofen (day 70 vs day 42). Two dogs on the supplement had side effects and were taken out of the study.
What this means - more context
The supplement appears to help dogs with arthritis, but it takes longer to work than a standard NSAID. Since there was no dummy pill group, we cannot be 100% sure the improvement was not partly due to natural changes or owner expectations.
To assess the efficacy of an orally-administered glucosamine hydrochloride and chondroitin sulfate (Glu/CS) combination for treating confirmed osteoarthritis of the hips or elbows in dogs.
In a randomised, double-blind, positive-controlled, multi-centre trial, 35 dogs with osteoarthritis received Glu/CS or carprofen. Dogs treated with Glu/CS showed statistically significant improvements in pain, weight-bearing, and overall severity scores by day 70 (P<0.001). The onset of significant response was slower than for carprofen (day 70 vs day 42). The authors conclude that Glu/CS has a positive clinical effect in dogs with osteoarthritis.
Methods Used
Randomised, double-blind, positive-controlled, multi-centre trial. 35 dogs with confirmed osteoarthritis of hips or elbows were treated with oral glucosamine hydrochloride and chondroitin sulfate (Glu/CS) or carprofen (positive control). Dose and regimen not specified in abstract. Dogs were re-examined on days 14, 42, and 70, treatment was withdrawn, and dogs were re-assessed on day 98. Response was based on subjective veterinarian evaluations of pain, weight-bearing, and severity.
Main Finding
Glu/CS treatment significantly improved pain, weight-bearing, and overall severity scores by day 70 (P<0.001). Significant improvements appeared later than in carprofen-treated dogs (day 70 vs day 42).
Confidence Level
Moderate. Randomised, double-blind design reduces bias, but the lack of a placebo control and subjective outcome measures limit the strength of causal claims. Small sample size and withdrawals (including two adverse drug reactions in the Glu/CS group) also reduce confidence.
Study Flags
Red Flags
- •No placebo control group, so improvements cannot be definitively attributed to the supplement
- •Subjective veterinarian ratings rather than objective measurements like force plate gait analysis
- •Small sample size (35 dogs) and withdrawals, including two adverse drug reactions in the Glu/CS group
No biological mechanisms were identified in this study. This may be an epidemiological, observational, or survey-based study that reports associations rather than proposing causal biological pathways.
Surprising Findings
Dogs on the supplement improved significantly by day 70 even without a placebo group, but the benefit took 28 days longer to appear than in dogs on carprofen.
Many people assume nutraceuticals either work quickly or not at all. Here, the supplement produced measurable improvements, just slowly.
Practical Takeaways
If you try a glucosamine/chondroitin supplement for your dog's arthritis, commit to at least 70 days (10 weeks) before judging whether it works, since benefits were not significant before that point.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 516 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Animal RCT
Subject
Lower probability
on the GRADE evidence scale
Think of a study where sick dogs got a supplement and other sick dogs got a known pain medicine. Both groups got better, but there was no group that got nothing. So maybe the dogs would have gotten better anyway, and we can't be sure the supplement actually did anything. It's like taking two kinds of candy and feeling happier, but not checking if a kid who got no candy also felt happier.
Major conflicts — industry funding with significant control over the research. Reporting score and overall score cap have been reduced.
Strengths
- Prospective, randomized, double-blind design
- Use of a positive control (carprofen) provides a reference standard for comparison
- Multi-centre recruitment increases clinical diversity
Weaknesses
- Small sample size (35 dogs completed)
- No placebo control group, making it impossible to separate specific treatment effect from natural history or placebo effects
- Subjective outcome measures based on veterinarian assessment, not objective measurements like force plate gait analysis
Methodology
Evidence Keywords
Statistical Reporting
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Dogs with arthritis were given either a supplement called glucosamine/chondroitin or a standard pain medicine (carprofen). Vets checked the dogs at different times to see if they were in less pain and walking better.
Research results
After 70 days, dogs on the supplement were doing significantly better (P<0.001) in pain, weight-bearing, and overall condition. Improvement was slower than with carprofen (day 70 vs day 42). Two dogs on the supplement had side effects and were taken out of the study.
What this means - more context
The supplement appears to help dogs with arthritis, but it takes longer to work than a standard NSAID. Since there was no dummy pill group, we cannot be 100% sure the improvement was not partly due to natural changes or owner expectations.
To assess the efficacy of an orally-administered glucosamine hydrochloride and chondroitin sulfate (Glu/CS) combination for treating confirmed osteoarthritis of the hips or elbows in dogs.
In a randomised, double-blind, positive-controlled, multi-centre trial, 35 dogs with osteoarthritis received Glu/CS or carprofen. Dogs treated with Glu/CS showed statistically significant improvements in pain, weight-bearing, and overall severity scores by day 70 (P<0.001). The onset of significant response was slower than for carprofen (day 70 vs day 42). The authors conclude that Glu/CS has a positive clinical effect in dogs with osteoarthritis.
Methods Used
Randomised, double-blind, positive-controlled, multi-centre trial. 35 dogs with confirmed osteoarthritis of hips or elbows were treated with oral glucosamine hydrochloride and chondroitin sulfate (Glu/CS) or carprofen (positive control). Dose and regimen not specified in abstract. Dogs were re-examined on days 14, 42, and 70, treatment was withdrawn, and dogs were re-assessed on day 98. Response was based on subjective veterinarian evaluations of pain, weight-bearing, and severity.
Main Finding
Glu/CS treatment significantly improved pain, weight-bearing, and overall severity scores by day 70 (P<0.001). Significant improvements appeared later than in carprofen-treated dogs (day 70 vs day 42).
Confidence Level
Moderate. Randomised, double-blind design reduces bias, but the lack of a placebo control and subjective outcome measures limit the strength of causal claims. Small sample size and withdrawals (including two adverse drug reactions in the Glu/CS group) also reduce confidence.
Study Flags
Red Flags
- •No placebo control group, so improvements cannot be definitively attributed to the supplement
- •Subjective veterinarian ratings rather than objective measurements like force plate gait analysis
- •Small sample size (35 dogs) and withdrawals, including two adverse drug reactions in the Glu/CS group
No biological mechanisms were identified in this study. This may be an epidemiological, observational, or survey-based study that reports associations rather than proposing causal biological pathways.
Surprising Findings
Dogs on the supplement improved significantly by day 70 even without a placebo group, but the benefit took 28 days longer to appear than in dogs on carprofen.
Many people assume nutraceuticals either work quickly or not at all. Here, the supplement produced measurable improvements, just slowly.
Practical Takeaways
If you try a glucosamine/chondroitin supplement for your dog's arthritis, commit to at least 70 days (10 weeks) before judging whether it works, since benefits were not significant before that point.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 516 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Animal RCT
Subject
Lower probability
on the GRADE evidence scale
Think of a study where sick dogs got a supplement and other sick dogs got a known pain medicine. Both groups got better, but there was no group that got nothing. So maybe the dogs would have gotten better anyway, and we can't be sure the supplement actually did anything. It's like taking two kinds of candy and feeling happier, but not checking if a kid who got no candy also felt happier.
Major conflicts — industry funding with significant control over the research. Reporting score and overall score cap have been reduced.
Strengths
- Prospective, randomized, double-blind design
- Use of a positive control (carprofen) provides a reference standard for comparison
- Multi-centre recruitment increases clinical diversity
Weaknesses
- Small sample size (35 dogs completed)
- No placebo control group, making it impossible to separate specific treatment effect from natural history or placebo effects
- Subjective outcome measures based on veterinarian assessment, not objective measurements like force plate gait analysis
Methodology
Evidence Keywords
Statistical Reporting
Scoring
How strong is this study?
The study was done pretty carefully—dogs were randomly put into two groups, and the doctors didn't know which dog got which treatment. That helps prevent cheating or bias. But there were not very many dogs, and the improvement was judged just by looking, not with a machine. Also, because there wasn't a fake treatment group, we can't be 100% sure the supplement is what made the dogs better.
0 / 100
- COI disclosureconflicts of interest not disclosed
- Data availabilitydata not shared
- Code availabilitycode not shared
79 / 100
- Randomization+20/20
- Blinding+15/15
- Control group+15/15
- Sample size (n=35)+3.2/20
- Follow-up+10/10
100 / 100
23 / 100
- P-values+15/15
- Effect sizeno effect size reported
- Confidence intervalsno confidence intervals
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 516 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
This design cannot establish causation — the findings describe an association, not a cause. Although this is an RCT, it uses a positive control (carprofen) rather than a placebo. Without a placebo/no-treatment group, the observed improvements in dogs receiving glucosamine/chondroitin sulfate cannot be causally attributed to the treatment, as they might be due to natural disease progression, regression to the mean, or placebo effects. The design can only compare the supplement to an active drug, and no statistical between-group differences were reported.
Major COI
Major conflicts that significantly reduce study credibility
The study was funded by VetPlus Ltd., a company that likely manufactures the glucosamine/chondroitin product being tested. Although no explicit conflict of interest section is present, the funding constitutes a major conflict as the funder has a commercial interest in the outcome.
Funders
Conflict Details
VetPlus Ltd.: Received financial support for the study
BSAVA Petsavers: Funding for residency
Independent Analysis Safeguards
- Randomized double-blind design
- Positive-controlled trial
- Multi-centre trial
- Ethics committee approval and licensing
Funding from VetPlus Ltd., a company that likely manufactures the test product, presents a major conflict of interest. No conflict of interest declaration is visible in the provided sections. BSAVA Petsavers also funded an author's residency but without apparent industry connection. The study uses positive control (carprofen) and subjective outcome measures.