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Rapid Responses: Rapid Responses published:
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Dog credentials
- Herbert S. Skovronek, Ph. D. (24 September 2004)
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Glycosuria?
- Alexis Descatha (24 September 2004)
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Biophysical Semeiotics is more reliable and practical than dogs in diagnosing human bladder cancer.
- Sergio Stagnaro (24 September 2004)
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Sniffer dogs
- Carole Castles (24 September 2004)
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dogs' diagnostic skills part of bigger picture?
- Steven Scher, none (24 September 2004)
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Olfactory detection of cancers: might it be entangled?
- Richard G Fiddian-Green (24 September 2004)
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Detection of bladder cancer by dogs.
- Ramaswamy Manikandan (24 September 2004)
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That'll do
- David J. Wlody (24 September 2004)
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Hearty congratulations
- Hywel C Williams (25 September 2004)
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Non-independence of observations
- Thomas R Knapp (25 September 2004)
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Dogs should be kept on a lead.
- Phillip J. Colquitt (27 September 2004)
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Heterogeneity between cancer patients
- Thomas V Perneger (27 September 2004)
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Canine olfactory detection of pregnancy too.
- Rachel G Pryke (27 September 2004)
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It may be earlier than urine
- Adrian White (28 September 2004)
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Good study
- Avinash Manohar (30 September 2004)
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Was the trial blind?
- James T Teo, Cambridge CB2 2QQ (30 September 2004)
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Cause or association?
- Michael Leahy (1 October 2004)
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Smoking is not a confounder of the association between bladder cancer and selection of urines by dogs
- Carolyn M Willis, Susannah M Church, Claire M Guest, W Andrew Cook, Noel McCarthy, Anthea J Bransbury, Martin RT Church, John CT Church (6 October 2004)
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Points of clarification by the authors
- Carolyn M Willis, Susannah M Church, Claire M Guest, W Andrew Cook, Noel McCarthy, Anthea J Bransbury, Martin RT Church, John CT Church (7 October 2004)
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Where is the rest of the information?
- John Parkin (12 October 2004)
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On the need to read the full on-line version
- Carolyn M Willis, Susannah M Church, Claire M Guest, W Andrew Cook, Noel McCarthy, Anthea J Bransbury, Martin RT Church, John CT Church (13 October 2004)
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Another cancer detected by "pet scan"
- James S. Welsh, Madison, WI, USA 53792 (15 October 2004)
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"You are bloody dog" will no more be offensive in future?
- Dr. Naseem A. Qureshi MD, IMAPA, LMIPS (16 October 2004)
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Re: Comparison for Cancer Detection dogs and other scent specific detection dogs
- Stephen B. Phillips (27 March 2005)
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Harry Potter's familiars
- Robin Batteau (2 April 2005)
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My JR Terrier sniffs my nose and mouth every AM
- Linda A. Young, Thomas L. Wilding (26 August 2006)
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Herbert S. Skovronek, Ph. D., retired: research scientist/dog trainer Morris Plains, NJ 07950 USA
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Excellent paper supporting years of anectodal work by others. One disappointment, however, is the apparent use of untrained dogs and unidentifed breeds. There are gross differences in different breeds and at different training levels. It would be interesting to review the results by excluding the worst and the second worst of the six dogs. I suspect the success rate will increase dramatically. The same can perhaps be said about the trainer(s). Olfactory work is not just an extension of obedience performance. Further, the use of urine samples on petri dishes may be extremely generous and may actually overwhelm the dogs in their efforts to detect what are, presumably, very slight differences in odor profile. In our work we usually worked with no more than one or two drops of a chemical. Finally, it is very interesting, but unclear, how dried urine samples were used. Presumably volatile components would have been lost during the drying and transport. Did I miss something? It does appear in the "dog community" that there is more to the detection by dogs than volatility, and this may be a particularly useful product of this work. Competing interests: Probably not a conflict, but I have carried out research for USEPA using dogs to locate environmental contaminants. |
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Alexis Descatha, MD Unite de pathologie professionnelle, hop Poincaré, aphp, 92380 Garches, France
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I was very interested by the paper about olfactory detection of human bladder by dogs of Dr Wills et al. (BMJ vol. 329 25/09/04, p712). I think, as your acting editor notes, a good idea could lead to new findings. However, I was very surprised that some factors were not taking account, even in discussion: authors adjust their results on urinalysis, except the glycosuria. In last century, our fathers learn to diagnose diabetes mellitus by smelling and testing urine of subjects. This parameter was not mentioned in the article in the participant selection, analysis or discussion, even if it was probably measured. Thank you to light this point. Competing interests: None declared |
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Sergio Stagnaro, Specialist in Blood, Gastrointestinal, and Metabolic Diseases. Researcher in Biophysical Semeiotics. Via Erasmo Piaggio 23/8 16037 Riva Trigoso (Genova) Italy.
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Sirs, I dare to state that C.M. Willis’s et al. paper is really amusing (1). In fact, I know exactly that now-a-days, all around the world, diagnoses are made not by doctors, but by imaging departments and laboratory machines. Howeer, as regards dogs, in my opinion, one has firstly to rationally select people’s urine to identify individuals with bladder cancer on the basis of urine odour. At this point, it is sufficient for physicians the knowledge of Biophysical Semeiotics (2) (See web-site HONCode 233736, www.semeioticabiofisica.it), in order to recognize in a few minutes both individuals apparently healthy, but with Oncological Terrain “and” urinary bladder "oncological real risk", and urinary bladder cancer, of course. In addition, a physician can learn more rapidly such as physical semeiotics than a dog the new methods becoming trained to identify people with bladder cancer on the basis of urine odour, not to speak about biophysical -semeiotic differential diagnosis efficaciousness (3, 4). Finally, I think that it is more advisable that NHS authorities should invite physicians to study physical semeiotic advances, that have occurred over last 5 decades, than to train dogs to distinguish patients with bladder cancer on the basis of urine odour. 1) Willis CM., Church SM., Guest C., et al. Olfactory detection of human bladder cancer by dogs: proof of principle study. BMJ 2004;329:712 (25 September), doi:10.1136/bmj.329.7468.712 2) Stagnaro Sergio, Stagnaro-Neri Marina. Introduzione alla Semeiotica Biofisica. Il Terreno oncologico”. Travel Factory SRL., Roma, 2004. http://www.travelfactory.it/semeiotica_biofisica.htm 3) Stagnaro-Neri M., Stagnaro S., Cancro della mammella: prevenzione primaria e diagnosi precoce con la percussione ascoltata. Gazz. Med. It. – Arch. Sc. Med. 152, 447, 1993. 4) Stagnaro S., Sindrome percusso-ascoltatoria di Iperfunzione del Sistema Reticolo-IstiocitarioMin. Med. 74, 479, 1983 [ MEDLINE]. Competing interests: None declared |
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Carole Castles, General Practitioner Canberra 2600
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This puts a whole new spin on having your 'lab' tests done. I'm waiting for the paper on 'cat' scans. Competing interests: None declared |
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Steven Scher, retired government worker,now writing Bronx, NY 10463, USA, none
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I have long theorized (and have made known to researchers) that dogs sniff each other upon meeting for other than sexual or physical safety reasons. A dog can see and smell the sexual and agitation state of another dog from quite some distance. Why then the closeup "examination"? I believe that for evolutionary reasons the dog is able to detect the health of the other dog, for the sake of his own survival. By diagnosing life- threatening disease the dog would be able to avoid contact with another dog that would threaten its own health and survivability. If this theory is true, then it opens the possiblity of using dogs to indicate the presence of various diseases and health problems. Just a theory from a rank amateur. Steven Scher Competing interests: None declared |
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Richard G Fiddian-Green, FRCS. FACS c/o Maitland and Co, 44 Dover Street. London W1
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[SD checking with TD, 24.9.04] Rupert Sheldrake, former Research Fellow of the Royal Society, Knox Fellow at Harvard University and Director of Studies in Biochemistry and Cell Biology at Cambridge University, has published a book entitled, "Dogs That Know When Their Owners Are Coming Home: And Other Unexplained Powers of Animals". In it he describes a dog that was able to detect hypoglycamia and another than was able to detect an impending epileptic siezures. His experiments on the telepathic powers of a dog anticipating their owner's departure from work are particlarly interesting, the dog's anticipatory behaviour preceeding the owner's preparatory behavioural changes. His latest book, "The Sense of Being Stared At", extends his studies of what might be called telepathic powers to humans. His concluding remarks concerning his most recent investigations (1) are: "The fact that positive results [p<0.004 and < 0.0002] were still obtained when visual clues had been effectively eliminated by blindfolds, and auditory and olfactory clues by closed windows, implies that the sense of being stared at does not depend on the known senses. I conclude that peoples' ability to know when they are being looked at depends on an influence at present unknown to science". In terms of quantum theory telepathic powers might be transmitted at the speed of light as electromagnetic waves, instantly at speeds infinitely greater than the speed of light by entanglement, or both. "Entanglement [that is the instant communication between pairs of particles [hypothetically] located on opposite sides of the universe] has been verified experimentally since Einstein's death. [The verification is proof that] the theory of relativity is false for].. Einstein .[had]..acknowledged that his theory.. would be wrong if entanglement, or "spooky-action-at-a-distance" as he called it, were ever shown to be real for it would mean that it is indeed possible to travel faster than the speed of light"(2). His theory is based upon the assumption that the speed of light is constant which, somantics aside for some contend that entanglemnt does not violate the spirit of relativity, it might not be for the speed of light could be variable (3) and can even be stopped (4). [For those who like to learn more about entanglement, the "greatest mystery in physics", I recommend reading the very recent review written by Amir AczelHe an Associate Professor of Mathematical Sciences at Bentley College in Boston (5). It is very short and readable book that, as far as I do recall did not have any equations in it with the possible exception of E= MC2]. Velocity is the distance traveled per unit of time. If the speed of light is variable then so is time provided that the distance between two objects remains the same. That would mean that our understanding of the passage of time in history could be wrong and the Biblical dating of Creation conceivably even correct (6). If entanglement is real, and the distance between two objects still remains the same, time should cease. Reductio ad absurdum? Not if the Alice hypothesis is valid for the distance between two objects will only exist in their fermionic phases of existence and should be as wide as the universe [15 billion miles] in the intervening bosnic phases of existence when time too does not exist (7). If telepathic skills are bosonic then the distance between objects, certainly on earth, is as insignificant as the distance between people having transcontinental conversations on cells phones. What is more time is also insignificant for there is no distinction between present, past and future in the hypothetical bosonic phases of existence. In other words a dog's telepathic abilities should not be limited by either distance or time. As all information is encoded in every particle present in the universe in the the bosnic phases of existence a dog's ability to know when its ownner was coming home should not also be limited by either distance or time. Rupert Sheldrake has called this connectivity between people animals and even objects a morphic field. In this report (8) the dog's ability to recognise a characteristic bladder cancer from a sample of urine was independent of other chemical aspects of the urine detectable by urinalysis. Was then the dog's ability to detect cancers entirely dependent upon olfactory signals, ones possibly from formaldehyde, alkanes, benzene derivatives or other volatile molecules unique to the cancer? What then of hypoglycaemia and impending siezures? Might their detection depend upon telepathic signals? The answer might be both for, as in quantum cryptography and teleportation, two signals are required for recognition only one of which is entangled. The signals detected by dogs might, therefore, be similar to those apparently detected by clairvoyants when given an object once belonging to the subject in question to handle in attempting to pick up telepathic signals from the subject's past or future? 1. Sheldrake R The "sense of being stared at" does not depend on known sensory clues. Riv Biol. 2000 May-Aug;93(2):237-52. 2. Protecting Einstein's reputation with weasel words Richard G Fiddian-Green bmj.com, 2 Sep 2003 eeLetter re: Patrick Bracken and Philip Thomas Time to move beyond the mind-body split BMJ 2002; 325: 1433-1434 3. Joao Magueijo. Amir D. Faster Than the Speed of Light: The Story of a Scientific Speculation 4. Hau, LV. Frozen light. Scientific American special edition on "The edge of physics" updated from the July 2001 issue. 5. Aczel Entanglement: The Greatest Mystery in Physics 6. Might scientists benefit from studying Creation? Richard G Fiddian-Green (26 April 2003) eLetter re: Scott Gottlieb Creationists accuse biology professor of discrimination BMJ 2003; 326: 354 7. Alice hypothesis= alternating type IIA and IIB string theories? Richard G Fiddian-Green (10 March 2004) eLetter re: Brian Olshansky and Larry Dossey Retroactive prayer: a preposterous hypothesis? BMJ 2003; 327: 1465-1468 8. Carolyn M Willis, Susannah M Church, Claire M Guest, W Andrew Cook, Noel McCarthy, Anthea J Bransbury, Martin R T Church, and John C T Church Olfactory detection of human bladder cancer by dogs: proof of principle study BMJ 2004; 329: 712-0 Competing interests: None declared |
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Ramaswamy Manikandan, Specialist Registrar Urology Arrowe Park Hospital, Wirrall CH49 5PE
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Dear Sir/Madam, I read this article with interest and applaud the authors for the pains they have taken to do this study. I do have some comments to make. I presume that all the persons in the control group had upper tract imaging in the form of an intravenous urogram(IVU) or ultrasound scan as this is important to rule out tumor of the upper tracts, which could still show the same changes in the urine as bladder cancer.This is because the urinary tract is almost entirely lined by transitional cell. Although the authors were not trying to prove the clinical utility of their study it would have been very useful for us to know how many of these patients with bladder cancer whom the dogs correctly picked up also had a positive urine cytology. This is because urine cytology has a low sensitivity but high specificity and positive predictive value[1]. We are still searching for the ideal urine test to pick up transitional cell cancers of the urinary tract. As the authors have speculated although the study will not bring about an immedicate change in the way bladder cancer or for that matter any cancers are diagnosed it may lead on to further studies to evaluate the possiblity of picking up baldder cancer based on the the chemical composition of the urine in bladder cancer. Reference: 1.Messing EM: Urothelial tumors of the urinary tract.In Walsh PC, Retik AB, Vaughan ED, Wein AJ eds. Campbell's Urology.W.B.Saunders, Philadelphia,2002;2732-2784. Competing interests: None declared |
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David J. Wlody, Attending Anesthesiologist SUNY Downstate Medical Center, Brooklyn NY 11203
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My suggestion for replicating this paper would be to use border collies as subjects. Not only would they identify patients with malignancies, but I suspect they could provide a cytologic diagnosis as well. Competing interests: None declared |
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Hywel C Williams, Professor of Dermato-Epidemiology University of Nottingham
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Many people thought that I was mad when I suggested that dogs might be able to detect various forms of human cancer in that letter to the Lancet back in 1989 with Andrew Pembroke. Various half-hearted attempts have been made to take the idea further since then, but this is the first study that bears any scientific credibility. I am so glad that some people took me seriously - well done Carolyn Willis and team. Competing interests: Involved in similar research |
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Thomas R Knapp, Prof. Emer. The Ohio State University, Columbus OH 43210
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This is an interesting article, but the observations are not statistically independent (as acknowledged by the authors on page 5) and the data should not be pooled across the six dogs. Competing interests: None declared |
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Phillip J. Colquitt, Technician/RN Independent comment
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Here in Brisbane, one can be fined, and rightly so, for allowing one's dog to be unleashed in public. The problem seems to be with the dog owners, who invariably have implausibly docile names for their pet - eg. a Doberman with two inch gleaming canine teeth, a manic look in his eye, and disgusting hypersalivation, causes a dear old grandmother with a pacemaker to near arrest, yet goes by the name of "baby". The dog seems to know the owner is daft to treat him like a pansy, as he ignores the call to come, and proceeds to sniff every innocent crotch that passes by. I just hope the pro-dog lobby don't use this study to argue for fine reduction, but rather take it to mean a minority of dogs are useful. PS. Do they sniff better on or off the leash, or were they all loose in the lab? Competing interests: None declared |
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Thomas V Perneger, professor of health services evaluation CH-1211 Geneva, Switzerland
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Congratulations for this very nice study. An interesting finding is that dogs had more success with some patients than with others, with a range of 0 to 6 positive identifications out of 6 (Table 2). The difference between patients in the number of successes is statistically significant (Fisher exact test done on StatXact, p=0.0013). Could it be that aromatic compounds are released by some tumours and not by others? How many positive identifications out of 6 should we regard as a strong indication that a bladder cancer is present? Below are shown expected probabilities for 0 to 6 positive identifications under the null hypothesis (chances of success: 1/7) and under an alternative hypothesis that dogs will detect aromatic compounds 80% of the time that these compounds are present: Nb positive= 0, Prob(null)= 0.397, Prob(alt.)= 0.00006, Likelihood ratio= 0.00016 Nb positive= 1, Prob(null)= 0.397, Prob(alt.)= 0.0015, LR= 0.0039 Nb positive= 2, Prob(null)= 0.165, Prob(alt.)= 0.0154, LR= 0.093 Nb positive= 3, Prob(null)= 0.037, Prob(alt.)= 0.082, LR= 2.23 Nb positive= 4, Prob(null)= 0.0046, Prob(alt.)= 0.246, LR= 53.5 Nb positive= 5, Prob(null)= 0.00031, Prob(alt.)= 0.393, LR= 1285.0 Nb positive= 6, Prob(null)= 0.000008, Prob(alt.)= 0.262, LR= 30841.0 Therefore, when 4, 5, or 6 dogs out of 6 identified a sample as positive, we should be pretty sure that aromatic compounds were present (very high likelihood ratios). In contrast, when 0 or 1 dogs identified the sample, we should be pretty confident there was nothing to detect. The case of 2 and 3 identifications is somewhat ambiguous. Note that several controls had 2 or even 3 positive identifications (Table 2 of paper). It appears that 3 patients (1, 2, 5) were positive for aromatic compounds, 4 other patients were definitely not (3, 7, 8, 9), and 2 were ambiguous (4 and 6). The limited overall sensitivity of the method (41%) is not due to poor performance by dogs, but rather to the fact that some tumours do not release aromatic compounds. Competing interests: None declared |
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Rachel G Pryke, GP Redditch
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Dear Sir, I am unsurprised at the findings of Willis et al, BMJ vol 329 25 September 2004, that dogs can detect bladder cancer by smell alone. Our 12 year old Golder Retriever, Polly, has been doing home pregnancy tests for years. A highly distinctive and enthusiastic crotch-snaffling has given away several of our visitors' secrets before they had chance to air their news verbally. Polly's ability was noted during my first pregnancy and confirmed during my subsequent two pregnancies, as well as during visits from pregnant friends. No other medical condition or status (such as having spilt food on trousers) has ever elicited the same response, although I admit to having run no controlled trial of her capabilities. This natural talent is hard to understand in evolutionary terms, but socially I imagine it forwarned her of her impending reduction in household status, as she dropped down the family priority ladder with each new arrival. I would imagine there are many more families that are aware of peculiar medically interesting quirks in their pets. Yours
Competing interests: None declared |
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Adrian White, Chief Executive Canada L0S 1E1
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My English setter changed its behaviour towards me long before I had a PSA test or biopsy or the most basic rectal examination that determined the existence of prostate cancer. He would not get off my lap in the evening, something he never did before, and he was 100 pounds to boot. He tried to put heat on the cancer zone of which I was blissfully unaware. I had radical surgery over a year ago, the cancer is gone, the nerves were not damaged, and everything is back to normal. I wish I understood at the time what he was trying to tell me. Adrian White Competing interests: None declared |
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Avinash Manohar, SHO Mid Yorkshire Hospitals
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Congratulations to the authors of this wonderful study.Its amazing to note that our canine friends could detect urinary tract cancers. But Im concerned whether hapless junior doctors would need to request a doberman to perform CT scans in future! Competing interests: None declared |
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James T Teo, SHO in Neurology Addenbrooke's Hospital, Cambridge CB2 2QQ
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Editor - Willis et al's article on the use of dogs to distinguish between the urine of patients with bladder cancer and negative controls do show very dramatic results but I cannot help but recall the story of 'Clever Hans the calculating horse'. In 1888, Wilhelm Von-Osten presented a trained stallion 'Clever Hans' able to perform arithmetic, work with fractions and identify musical tones. The horse communicated this ability by converting answers to questions into numbers and tapping out these numbers with its hoof. This was replicated many times in front of audiences of all sizes and all education levels. Finally in 1907, the psychologist Oskar Pfungst disproved the arithmetic ability of 'Clever Hans' with a series of experiments putting the horse's questioner out of sight. Pfungst concluded that the horse was picking up on subtle cues in the body language of its questioner: the frown, the flaring of nostrils, etc. The horse knew which was the right answer by reading the reactions of its human audience and stopping when it had stomped just the right number and the questioner unconsciously tenses up in anticipation (1). Willis et al has not indicated whether the experiment was adequately blinded. The dogs may not be picking up cues in the urine but in the unconscious responses of their human trainers or the experimenters. All human contact with the dog during the training and the testing needs to be blinded. References: (1) Pfungst, O. (1907); Das Pferd des Herrn von Osten (Der Kluge Hans): Ein Beitrag zur experimentellen Tier- und Menschen-Psychologie; Leipzig. English translation by C. L. Rahn in Pfungst, O. (1911); Clever Hans (The Horse of Mr. Von Osten): A Contribution to Experimental Animal and Human Psychology; New York. Competing interests: None declared |
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Michael Leahy, Senior Lecturer Medical Oncology Academic Unit of Oncology, St. James's University Hospital, Leeds, LS9 7TF
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Dear sir, The study by Willis et al testing whether dogs can detect signs of bladder cancer in urine, may be the occasion for an amusing cover for the BMJ but this should not be an excuse for relaxing intellectual rigor when assessing the experiment. Neither the authors nor the commentator point out that the study design is unable to distinguish cause from association – a basic logical error. The dogs may be detecting “tumour related volatile compounds” or they may be detecting a substance in the urine that is associated with an increase risk of cancer. The most obvious candidate would be from cigarette smoking, which would be rather unoriginal, but it could also be other as yet unidentified substances. Furthermore, while the dogs may only be 41% accurate at detecting urine from people already diagnosed with cancer, the results would also be consistent with a higher accuracy for detecting patients at risk of cancer. The authors should follow up their interesting preliminary study rigorously and the BMJ should stick to the Christmas edition in letting down its usual standards of review. Competing interests: None declared |
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Carolyn M Willis, Senior Clinical Scientist Department of Dermatology, Amersham Hospital, Amersham, Bucks HP7 0JD, Susannah M Church, Claire M Guest, W Andrew Cook, Noel McCarthy, Anthea J Bransbury, Martin RT Church, John CT Church
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In response to comments by Michael Leahy, we would like to point out that we were well aware of the need to consider lifestyle and environmental factors associated with bladder cancer. As stated in our Methods section, we collected comprehensive data on each participant, including occupation, dietary intake, hobbies, medication, and, most importantly, smoking habits. We specifically designed the training regimen to take into account the association between smoking, bladder cancer and the possible presence of tobacco related odours in the urine. During training, the dogs were taught to ignore the urine of control individuals who smoked, and were presented with positive bladder cancer urines from non-smokers, as well as smokers. In the evaluation tests, all runs containing a bladder cancer patient who smoked included at least two controls who were smokers. We did not measure metabolites from tobacco in the urine, but based on self report there was no obvious tendency for the dogs to preferentially select the urine from smokers. Specifically, 41% of selected urines were from self described “current or recent smokers” compared to 43% of non-selected urines. 37% of selected urines were from individuals who reported smoking one or more cigarettes on the day before their urine sample, compared to 33% who reported smoking no cigarettes on this day. Moreover, adjustment for smoking status has essentially no effect on the observed association between presence of cancer and odds of selection as indicated in the following table. Table. Effect of adjustment for tobacco smoking status on the odds of selection Model, Odds ratio* ______________________________________________________ Base (cancer) 4.1 + Usual cigarettes per day 4.1 + Cigarettes on day of urine sample 4.2 + Time since stopping smoking in week** 4.2 + Usually smoke (any amount) 4.1 + Smoked on day of sample (any amount) 4.4 ______________________________________________________ * Odds of selection among individuals with bladder cancer (transitional cell carcinoma) compared to among those without from a conditional logistic regression model. ** Zero for current smokers and 100 for non-smokers or smokers stopping more than 100 weeks before sample. None of the bladder cancer patients whose urine was used during testing was in a high risk occupation for the development of bladder cancer. Furthermore, there was no over-representation in terms of dietary intake (including tea, coffee or alcohol), or exposure to chemicals used for domestic purposes, such as paints, solvents and pesticides, amongst this group. Competing interests: Authors of the paper |
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Carolyn M Willis, Senior Clinical Scientist Department of Dermatology, Amersham Hospital, Amersham, Bucks, HP7 0JD, Susannah M Church, Claire M Guest, W Andrew Cook, Noel McCarthy, Anthea J Bransbury, Martin RT Church, John CT Church
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We would like to respond to a number of the comments made about our study:- 1. On the subject of glycosuria, as we mentioned in the Discussion, we did include control individuals with diabetes during the training phase, so that we could train the dogs to ignore the associated smells. None of the nine bladder cancer patients whose urine was used in the final testing phase exhibited glycosuria, on dipstick urinalysis. We did not, therefore, consider it necessary to include control individuals with glycosuria. 2. In response to the interesting comments made by Ramaswamy Manikandan, we took the decision that healthy controls under the age of 30 years were unlikely to have cancer, either in the urinary tract, or elsewhere, and so relied on a detailed medical history alone. For control patients attending the urology department, the majority did undergo intravenous urograms or ultrasound scans to exclude upper tract tumours, but a number did not. We were, therefore, very conscious of the possibility that control individuals with undiagnosed malignancies may be inadvertently included. This is why, as we explained in our Discussion, we decided at the outset not to pool the urine of controls for training purposes, but to use each one individually. As highlighted in our paper, the dogs did pick up a control patient with a transitional cell carcinoma in the right kidney during the latter part of training, which had not, at that stage, been diagnosed. During the test runs, it could be argued that any undiagnosed cancer within the controls would have lowered the dogs’ combined accuracy rate for bladder cancer. As it was, we were able to show statistically that the dogs could identify bladder cancer patients with a significantly greater success rate than that expected by chance alone. Regarding urine cytology, this was performed on only two of the nine bladder cancer patients whose urines were used in the test runs. In neither case was malignancy diagnosed by this method. However, the first of these (described as TCC 4 in Tables 1 and 2 of the on-line version, with a grade/stage of G2 pTa ) was selected by 3 of the 6 dogs, whilst the second (TCC 5, also G2 pTa) was picked out by 5 of the 6 dogs. Clearly, this sample size is too small to make any meaningful conclusions, but the comparison is, nevertheless, interesting and will be looked at further in the future. 3. The truncated printed version of our paper omitted some important aspects of the study’s methodology which appear, in full, in the on-line version. The formal test runs were strictly blinded, with the dog trainers and researchers in the building in which the tests were conducted being totally unaware of the identity of each urine sample. During training, it is necessary for the trainer to know the position of the positive sample some of the time, so that they can immediately reward the dog for a correct indication. However, regular blinded runs are also necessary to avoid the expectation of a reward on every occasion, and to ensure that unconscious cues transmitted from human to dog are not influencing the selection process. Competing interests: Authors of the paper |
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John Parkin, SpR Urology Walsgrave Hospital, Coventry, CV2 2DX
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Dear Editor Interesting as this subject of dogs detecting cancer by smell is, I find this paper dissappointing. As it is such a novel approach, surely it would have been worth compiling a more comprehensive study. Firstly, there is virtually no information with regard to the patients in respect of grade or stage of the bladder cancer, and at the very least a comparison should have been made with urine cytology. It has been clearly demonstrated that the higher the grade the greater the accuracy of urine cytology. Secondly, it would be interesting to know the results of other more experimental laboratory tests that have been suggested for the detection of bladder cancer such as Immunocyt, BTAstat, NMP22, Lewis X and urovision. Non of these provide the diagnostic accuracy that is required, such that cystoscopy and upper tract imaging with IVU or ultrasound remain the gold standard investigations for suspected bladder cancer. One has to say that this study suggests that the canine olifactory sense is unlikely to replace these. It would appear that in the haste for sensational news, that appeals to a wider audience these omissions have been ignored. Competing interests: None declared |
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Carolyn M Willis, Senior Clinical Scientist Department of Dermatology, Amersham Hospital, Amersham, Bucks, HP7 0JD, Susannah M Church, Claire M Guest, W Andrew Cook, Noel McCarthy, Anthea J Bransbury, Martin RT Church, John CT Church
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In response to comments made by John Parkin, we would like to point out, yet again, that it is the policy of the BMJ to print abridged papers, with the complete version being published on-line. Reference to this fact is made in the printed version of our paper no fewer than five times. Had John Parkin read the full paper he would have seen that Table 1 provides the grade and stage of the bladder cancers used in the final evaluation tests. He would also have seen that we make it clear in the Introduction that our intention, at this early stage, was not to investigate the clinical usefulness of the dogs’ olfactory capabilities, but to conduct a simple “proof of principle” experiment. John Parkin’s closing remarks are not worthy of further comment. Competing interests: Authors of the paper |
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James S. Welsh, Associate Professor of Human Oncology University of Wisconsin-Madison, Madison, WI, USA 53792
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SD asked for permission 15.10.04 Willis and colleagues are to be commended for their fascinating, well -designed and well-executed study. (1) Up until then there was only sparse, anecdotal evidence suggesting that dogs might truly be able to detect human malignancies. Their study compliments a recent study in which dogs were trained to identify melanoma in tissue samples and were then tested for their ability to detect melanoma lesions on human subjects. (2) In both investigations, the dogs detected malignancies in supposed controls. These studies bolster the idea that dogs may someday prove useful in the early detection of cancer. Such experimental investigations are of great interest to me, as I had encountered a patient who claimed that her dog’s incessant sniffing led to her finding of a breast mass that proved malignant. Due to the lack of substantiating literature to back up her claim, most of her medical care team brushed this off as coincidence, particularly since the lesion was internal rather than cutaneous as in other anecdotal reports. Professor Hywel Williams' well- known case of a melanoma being detected by the patient's dog (3) is now supported by experimental evidence. Our unpublished case suggests that dogs, in rare situations, may also detect non-cutaneous malignancies. Work such as that by Willis at al should spur on further rigorous investigation into this intriguing area. 1. Willis CM, Church SM, Guest CM, Cook WA, McCarthy N, Bransbury AJ, Church MR, Church JC. Olfactory detection of human bladder cancer by dogs: proof of principle study. BMJ. 2004; 329(7468):712-4. 2. Pickel D, Manucy GP, Walker DB, Hall SB, Walker JC. Evidence for canine olfactory detection of melanoma. Applied Animal Behaviour Science. 2004; 89: 107-116. 3. Williams H, Pembroke A. Sniffer dogs in the melanoma clinic? Lancet. 1989; 1:734. Competing interests: None declared |
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Dr. Naseem A. Qureshi MD, IMAPA, LMIPS, Director, CME&R POBox.2292, Buraidah Ment. Halth. Hosp., Saudi Arabia.
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Dear Carolyn, Trained dogs guard our houses as well as farms. Likewise they detect illicit substances, drugs, explosives, human remains at different settings and thus help criminal/justice department in apprehending criminals. Furthermore, dogs satisfy both actively and passively sexual needs of perverted humans-men and women. Trained dogs now help medical and paramedical staff in detecting several types of cancers; melanoma and its metastases; prostatic carcinoma; lung cancer; breast cancer; and urinary bladder carcinoma. All these cancers are linked with some types of volatile substances which are detected by trained dogs. In addition, untrained dogs do a lot for their own species' sustainment. In light of all this, when a person says to other person "you are bloody dog" may not be offensive in near future. Is it okay or just my peculiar thinking? Reference: Carolyn M Willis, Susannah M Church, Claire M Guest, W Andrew Cook, Noel McCarthy, Anthea J Bransbury, Martin R T Church, and John C T Church. Olfactory detection of human bladder cancer by dogs: proof of principle study. BMJ 2004; 329: 712-0. Competing interests: None declared |
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Stephen B. Phillips, Professional Dog Trainer 1214 West State Street Olean, New York 14760
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"We needed them to learn to recognise an odour signature for cancer from among the hundreds present in urine, without recourse to the "pure" source of the odour. This makes it very different from training dogs to detect, for example, drugs or explosives." Actually, detection of target odor is detection of target odor. We do not know exactly what the K-9s are indicating on when they are taught to find marijuana or cocaine or C-4 or gunpowder. The dogs don't talk, so we have no way of knowing the exact signature scent in the whole whole scent of any compound they are responding to. Using pseudo scents to train a drug dog illustrates this. Anyone who has used pseudo narcotic scents to train with knows that the pseudo scents do not smell like the whole scent of the target odor. A dog trained only on pseudo narcotics odors will respond by going to the full trained responce when put on real drugs. The reverse, however, is not always true. The reason is that the pseudo scents are only a small make up of signature scents that are exclusive to the target odor. Other signature scents that are found in the target odor that are not exclusive to it (found in other odors) are not present. The dog trained on only real drugs, is looking for the signature scents found in the pseudo along with other nonexclusive signature scents found in the target odor. Without the other nonexclusive signature scents found in the real drug odor being present with the exclusive signature scents, the dog does not recognise the pseudo as the target odor he was trained to find because he is looking for the whole scent picture, not just the signature scents exclusive to the target odor. The result is that he will show interest in the pseudo odor, but not go to trained final responce. As far as teaching the dog to respond to cancerous tissue or urine, the signature scents of the cancerous urine and tissue exclusive to the urine and tissue of cancer patients has yet to be determined. I believe the dogs percentage of accuracy could be greatly improved by training the dogs specifically on the cancerous urine and tissue first until a reliable trained final responce is obtained, and then working the dogs on lead and using lineups of samples rather than letting the dogs wander and try and locate sample on thier own. Any good detection dog team is just that, a team. The handler guides the dog through the areas to be searched, and interperates the dog's responces. The dog does the scent work. One without the other is useless, reguardless of how good they are. Both the dog and the handler have to be trained, as well as conducting regular maintainance training with thier trainer once the initial training is done to ensure reliability. The anology of the dog being trained to find a bomb within a bomd is a little misleading also. If a dog is trained to locate a specific type of wood, say Redwood, and then trucks full of logs are examined to find hidden Redwood (this has been done) is the dog not able to do it because it is really "a tree within a tree"? That is absolutely not the case. As long as the target odor used to train the dog is there, it would not matter that you are inspecting mutiple samples of tissue or urine. The only tissue or urine that would cause the dog to go to trained final responce would be the samples with the trained target odor. I also would like to see what the criteria was to select the dogs you trained in the first place. I believe if the dogs were selected by the types and amount of drive needed to do detection work, the percentage of accuracy would have been dramatically higher as well. THE MOST IMPORTANT PART of training detection dogs of any kind is having the proper K-9 candidates to train in the first place. A mediocre detection dog candidate with all the best training in the world will still be a mediocre detection dog. Just my own ideas looking at it from a dog trainer's point of view! Steve Phillips www.thedogguy.net Competing interests: Other than being a detection dog trainer with an interest, I am not currently involved in any cancer detection program. |
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Robin Batteau, music Westport Connecticut US 06880
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When it comes to medical magic or any other, the importance of animal familiars won't surprise anyone familiar with Harry Potter. In ancient times, doctors tasted patients' urine to test for disease. Medicine's come a long way. Today, doctors are much more likely to be invited for cocktails. When people meet, we greet each other with a "how are you?" So do dogs, just with a different organ, and they get a much more honest answer. It would be more of a surprise if they actually couldn't sense illness by scent. Thank you for your wonderful research. More, please. Competing interests: None declared |
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Linda A. Young, retired florist na, Thomas L. Wilding
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I have been sick with unexplained urinary tract problems, intersticial cisitis, etc, for the last couple of years, making my life miserable, and limiting my activities and causing severe depression. I am 63 years old. Every morning, my Jack Russell Terrier does a thourough check of my nose and mouth, intensly,sniffing as tho he were checking out a mole hole. Could he be smelling a cancer that has not been detected? I am the only one in the family he does that to. Sincerely, Linda Young Competing interests: None declared |
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