A trained dog was able to accurately identify thyroid cancer in almost 90% of human urine samples, an international conference has been told.

According to US researchers, the use of canine scent detection for this type of cancer is a non-invasive and inexpensive method of detecting a disease that can be initially difficult to diagnose.

"Current diagnostic procedures for thyroid cancer often yield uncertain results, leading to recurrent medical procedures and a large number of thyroid surgeries performed unnecessarily," explained the study's senior investigator, Dr Donald Bodenner, of the University of Arkansas for Medical Sciences (UAMS).

His colleagues trained a rescued male German shepherd-mix called Frankie to recognise the scent of cancer in thyroid tissue obtained from a number of patients.

Dr Bodenner pointed out that the dog's accuracy in detecting thyroid cancer in urine samples was only slightly less than the accuracy associated with fine-needle aspiration biopsy - the method which is often used to test for thyroid cancer.

"Frankie is the first dog trained to differentiate benign thyroid disease from thyroid cancer by smelling a person's urine," noted Dr Arny Ferrando also of (UAMS) .

For this study, 34 patients provided a urine sample before undergoing a biopsy and surgery for suspicious nodules in their thyroid.

In 15 of the cases, the surgical result determined thyroid cancer, while the remaining 19 cases were found to be benign.

The urine samples were then presented to Frankie by a gloved dog handler. The dog handler and the person recording the results were unaware which samples belonged to people with cancer.

If the dog detected cancer, he lay down. If he did not, he turned away from the sample.

Frankie was correct in 30 out of 34 of the samples - he correctly identified almost 87% of the thyroid cancer samples and almost 90% of the benign samples

"Scent-trained canines could be used by physicians to detect the presence of thyroid cancer at an early stage and to avoid surgery when unwarranted," Dr Bodenner suggested.

He said that they plan to expand this programme by training two more dogs to sniff out cancer in human urine samples.

Details of these findings were presented at the Endocrine Society's 97th annual meeting in San Diego.