A Lesson in Standardization - Subtle Aspects of the Processing of Samples Can Greatly Affect Dogs' Learning.

Training new medical odors presents challenges in procuring sufficient target samples, and suitably matched controls. Organizations are often forced to choose between using fewer samples and risking dogs learning individuals or using differently sourced samples. Even when aiming to standardize all aspects of collection, processing, storage and presentation, this risks there being subtle differences which dogs use to discriminate, leading to artificially high performance, not replicable when novel samples are presented. We describe lessons learnt during early training of dogs to detect prostate cancer from urine. Initially, six dogs were trained to discriminate between hospital-sourced target and externally-sourced controls believed to be processed and stored the same way. Dogs performed well: mean sensitivity 93.5% (92.2-94.5) and specificity 87.9% (78.2-91.9). When training progressed to include hospital-sourced controls, dogs greatly decreased in specificity 67.3% (43.2-83.3). Alerted to a potential issue, we carried out a methodical, investigation. We presented new strategically chosen samples to the dogs and conducted a logistic regression analysis to ascertain which factor most affected specificity. We discovered the two sets of samples varied in a critical aspect, hospital-processed samples were tested by dipping the urinalysis stick into the sample, whilst for externally sourced samples a small amount of urine was poured onto the stick. Dogs had learnt to distinguish target aided by the odor of this stick. This highlights the importance of considering every aspect of sample processing even when using urine, often believed to be less susceptible to contamination than media like breath.

How effective are trained dogs at alerting their owners to changes in blood glycaemic levels?: Variations in performance of glycaemia alert dogs.

AIMS: Domestic dogs are trained to a wide variety of roles including an increasing number of medical assistance tasks. Glycaemia alert dogs are reported to greatly improve the quality of life of owners living with Type 1 diabetes. Research into their value is currently sparse, on small numbers of dogs and provides conflicting results. In this study we assess the reliability of a large number of trained glycaemic alert dogs at responding to hypo- and hyper-glycaemic (referred to as out-of-range, OOR) episodes, and explore factors associated with variations in their performance. METHODS: Routine owner records were used to assess the sensitivity and specificity of each of 27 dogs, trained by a single UK charity during almost 4000 out-of-range episodes. Sensitivity and positive predictive values are compared to demographic factors and instructors' ratings of the dog, owner and partnership. RESULTS: Dogs varied in their performance, with median sensitivity to out-of-range episodes at 70% (25th percentile = 50, 75th percentile = 95). To hypoglycaemic episodes the median sensitivity was 83% (66-94%) while to hyperglyaemic episodes it was 67% (17-91%). The median positive predictive value (PPV) was 81% (68-94%), i.e. on average 81% of alerts occurred when glucose levels were out of target range. For four dogs, PPV was 100%. Individual characteristics of the dog, the partnership and the household were significantly associated with performance (e.g., whether the dog was previously a pet, when it was trained, whether its partner was an adult or child). CONCLUSIONS: The large sample shows that the individual performance of dogs is variable, but overall their sensitivity and specificity to OOR episodes are better than previous studies suggest. Results show that optimal performance of glycaemic alert dogs depends not only on good initial and ongoing training, but also careful selection of dogs for the conditions in which they will be working.

Canine Olfactory Thresholds to Amyl Acetate in a Biomedical Detection Scenario.

Dogs' abilities to respond to concentrations of odorant molecules are generally deemed superior to electronic sensors. This sensitivity has been used traditionally in many areas; but is a more recent innovation within the medical field. As a bio-detection sensor for human diseases such as cancer and infections, dogs often need to detect volatile organic compounds in bodily fluids such as urine and blood. Although the limits of olfactory sensitivity in dogs have been studied since the 1960s, there is a gap in our knowledge concerning these limits in relation to the concentration of odorants presented in a fluid phase. Therefore, the aim of this study was to estimate olfactory detection thresholds to an inert substance, amyl acetate presented in a liquid phase. Ten dogs were trained in a "Go/No go" single scent-detection task using an eight-choice carousel apparatus. They were trained to respond to the presence of solutions of amyl acetate diluted to varying degrees in mineral oil by sitting in front of the positive sample, and not responding to the 7 other control samples. Training and testing took place in an indoor room with the same handler throughout using a food reward. After 30 weeks of training, using a forward chaining technique, dogs were tested for their sensitivity. The handler did not assist the dog during the search and was blind to the concentration of amyl acetate tested and the position of the target in the carousel. The global olfactory threshold trend for each dog was estimated by fitting a least-squares logistic curve to the association between the proportion of true positives and amyl acetate concentration. Results show an olfactory detection threshold for fluid mixtures ranging from 40 parts per billion to 1.5 parts per trillion. There was considerable inter-dog difference in sensitivity, even though all dogs were trained in the same way and worked without the assistance of the handler. This variation highlights factors to be considered in future work assessing olfactory detection performance by dogs.

Volatile organic compounds as biomarkers of bladder cancer: Sensitivity and specificity using trained sniffer dogs.

In a previous canine study, we demonstrated that volatile organic compounds specific to bladder cancer are present in urine headspace, subsequently showing that up to 70% of tumours can be correctly classified using an electronic nose. This study aimed to evaluate the sensitivity and specificity which can be achieved by a group of four trained dogs. In a series of 30 double-blind test runs, each consisting of one bladder cancer urine sample placed alongside six controls, the highest sensitivity achieved by the best performing dog was 73% (95% CI 55-86%), with the group as a whole correctly identifying the cancer samples 64% (95% CI 55-73%) of the time. Specificity of the dogs individually ranged from 92% (95% CI 82-97%) for urine samples obtained from healthy, young volunteers down to 56% (95% CI 42-68%) for those taken from older patients with non-cancerous urological disease. Odds ratio comparisons confirmed a significant decrease in performance as the extent of urine dipstick abnormality and/or pathology amongst the control population increased. Importantly, however, statistical analysis indicated that covariates such as smoking, gender and age, as well as blood, protein and /or leucocytes in the urine did not significantly alter the odds of response to the cancer samples. Our results provide further evidence that volatile biomarkers for bladder cancer exist in urine headspace, and that these have the potential to be exploited for diagnosis.

Hearing dogs: a longitudinal study of social and psychological effects on deaf and hard-of-hearing recipients.

The organization Hearing Dogs for Deaf People provides assistance dogs that alert their deaf or hard-of-hearing recipients to key sounds, thus increasing their independence and also providing companionship. Fifty-one recipients took part in a longitudinal study to monitor the dogs' working performance over time and to examine the social and psychological effects of having a Hearing Dog. The Profile of Mood State (POMS) questionnaire and the General Health Questionnaire (GHQ) were used together with a Hearing Dog Questionnaire (HDQ) specifically developed for this study. There were a number of significant differences in measures of well-being between the period prior to placing the Hearing Dog and the period after placement, but there were no comparable differences during the year-long waiting period prior to placement of the dog. Recipients reported significant reductions in hearing-related problems such as response to environmental sounds; significant reductions in measures of tension, anxiety, and depression; and significant improvements in social involvement and independence. The longitudinal nature of this study supports evidence that these improvements persist for some time after the placement of a dog, with significant differences being reported, in many cases, up to 18 months after acquiring a dog.

Olfactory detection of human bladder cancer by dogs: proof of principle study.

OBJECTIVE: To determine whether dogs can be trained to identify people with bladder cancer on the basis of urine odour more successfully than would be expected by chance alone. DESIGN: Experimental, "proof of principle" study in which six dogs were trained to discriminate between urine from patients with bladder cancer and urine from diseased and healthy controls and then evaluated in tests requiring the selection of one bladder cancer urine sample from six controls. PARTICIPANTS: 36 male and female patients (age range 48-90 years) presenting with new or recurrent transitional cell carcinoma of the bladder (27 samples used for training; 9 used for formal testing); 108 male and female controls (diseased and healthy, age range 18-85 years--54 samples used in training; 54 used for testing). MAIN OUTCOME MEASURE: Mean proportion of successes per dog achieved during evaluation, compared with an expected value of 1 in 7 (14%). RESULTS: Taken as a group, the dogs correctly selected urine from patients with bladder cancer on 22 out of 54 occasions. This gave a mean success rate of 41% (95% confidence intervals 23% to 58% under assumptions of normality, 26% to 52% using bootstrap methods), compared with 14% expected by chance alone. Multivariate analysis suggested that the dogs' capacity to recognise a characteristic bladder cancer odour was independent of other chemical aspects of the urine detectable by urinalysis. CONCLUSIONS: Dogs can be trained to distinguish patients with bladder cancer on the basis of urine odour more successfully than would be expected by chance alone. This suggests that tumour related volatile compounds are present in urine, imparting a characteristic odour signature distinct from those associated with secondary effects of the tumour, such as bleeding, inflammation, and infection.