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By Alexander Freund
In a pilot study at the University of Helsinki, dogs trained as medical diagnostic assistants were taught to recognize the previously unknown odor signature of the COVID-19 disease caused by the novel coronavirus. And they learned with astonishing success: After only a few weeks, the first dogs were able to accurately distinguish urine samples from COVID-19 patients from urine samples of healthy individuals.
"We have solid experience in training disease-related scent detection dogs. It was fantastic to see how fast the dogs took to the new smell," says DogRisk group leader Anna Hielm-Björkman. After only a short time, the animals identified the urine of people infected by the novel coronavirus, known as SARS-CoV-2, almost as reliably as a standard PCR test.
The Finnish scientists are now preparing a randomized, double-blind study in which the dogs will sniff a larger number of patient samples. Only then will the scent tests be used in clinical practice.
Important Findings for Other Teams
The very rapid and promising findings from Finland are also important for other research teams, such as those in Great Britain and France, who are training sniffer dogs to detect COVID-19.
Fellow researchers from the German Assistance Dog Center (TARSQ) have also benefited from the Finnish results.
"No one could tell us with certainty whether training with the aggressive virus is dangerous or not for humans and dogs. We wanted to gather more information first before we started training because the German virologists advised us against it — after all, so little is known about the virus so far," explains Luca Barrett from TARSQ.
Where Does the Characteristic Smell Come From?
It is still unclear which substances in urine produce the apparently characteristic COVID-19 odor. Since SARS-CoV-2 not only attacks the lungs, but also causes damage to blood vessels, kidneys and other organs, it is assumed that the patients' urine odor also changes. This is something which the dogs, with their highly sensitive olfactory organs, notice immediately.
Certain diseases appear to have a specific olfactory signature that trained dogs can sniff out with amazing accuracy, Barrett says.
"According to one study, dogs can detect breast cancer with a 93% probability, for example. And lung cancer with a 97% probability," she says.
But dogs can also identify skin cancer, colon cancer, ovarian cancer or prostate cancer very reliably, according to Barrett. "The hit rate, which was not so good in the early days of training, has risen enormously in recent years," she says.
Hit Rate Decisive
Besides cancer, the dogs can also detect Parkinson's disease. Parkinson's sufferers smell different even years before they have the disease. "That's how we came up with the idea of training dogs as an early warning system for Parkinson's," Barrett says.
Dogs are also trained to detect malaria, but the hit rate is not yet satisfactory, she says. So far, the dogs recognize seven out of 10 infected persons, which is not enough.
A high hit rate is, of course, also absolutely necessary when training for the aggressive SARS-CoV-2 pathogen, according to Barret. "We hope that the hit rate for the coronavirus is significantly higher in the fully trained dogs; after all, it would be very dangerous if COVID-19 were not detected," she says
Trained Tracking Dogs
Dogs' ability to smell is about a million times better than that of humans. Humans have about 5 million olfactory cells, compared with 125 million for dachshunds and 220 million for sheepdogs.
Dogs also inhale up to 300 times per minute in short breaths, meaning that their olfactory cells are constantly supplied with new odor particles. In addition, dogs' noses differentiate between right and left. This spatial sense of smell allows the animals to follow a trail more easily.
During the training sessions, the dogs — mostly Labrador retrievers or retrievers in general, but also cocker spaniels or sheepdog breeds — are each trained for one scent. That can be the smell of a drug or an explosive, or, as here, the olfactory signature of a specific disease.This means that one dog cannot recognize several types of cancer.
The animals are trained with containers holding samples of breath or sweat, for example. As soon as they have identified the smell they are looking for, the dogs hear a click and get a treat. They are reliably trained for the one smell on this reward principle.
Great Potential, Great Skepticism
Drug and explosive detection dogs have been used for some time. But trained medical scent detection dogs are also now working in hospitals. For example, they sniff the bodies of patients with suspected skin cancer to try and detect the disease — only with the patients' consent, of course. So these skilled snufflers are helping doctors in diagnosing diseases and detecting them early on.
However, so far there are only very few medical detection dogs. The dog owners almost always work voluntarily and the trained sniffer dogs live in normal households. There is great skepticism, especially among traditional doctors and health insurance companies, even though the first indications given by the dog have to be followed by further medical tests anyway and a lot of time and costs could be saved by early cancer detection.
Possible Coronavirus Applications
If the findings from Finland are confirmed, the sniffer dogs with their extremely sensitive sense of smell could prove to be a great help in the fight against the new coronavirus.
Luca Barrett from TARSQ can easily picture coronavirus sniffer dogs being used in situations where there is a high risk of infection. For example, people attending football matches and other major events could be checked before they are admitted.
The dogs could also be employed at airports to scan people entering a country. "When the dogs go down the queue, they can detect if someone is healthy and can enter the country. But if a person smells of COVID-19, the handler could send that person to a coronavirus testing center instead," Barrett says. That is because a second test is still needed to confirm the dog's initial sniff detection.
Barrett says dogs could also be used to search for the virus on surfaces. For example, before passengers board an aircraft, a four-legged friend could first check whether the machine is free from SARS-CoV-2. Similar measures are planned for doctors' surgeries, aged care homes or nursing homes that have had to be evacuated because of COVID-19 cases. Before these are used again, a sniffer dog could check whether the environment is "clean."
Reposted with permission from Deutsche Welle.
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By Bob Jacobs
Hanako, a female Asian elephant, lived in a tiny concrete enclosure at Japan's Inokashira Park Zoo for more than 60 years, often in chains, with no stimulation. In the wild, elephants live in herds, with close family ties. Hanako was solitary for the last decade of her life.
Hanako, an Asian elephant kept at Japan's Inokashira Park Zoo; and Kiska, an orca that lives at Marineland Canada. One image depicts Kiska's damaged teeth. Elephants in Japan (left image), Ontario Captive Animal Watch (right image), CC BY-ND
Affecting Health and Altering Behavior<p>It is easy to observe the overall health and psychological consequences of life in captivity for these animals. Many captive elephants suffer from arthritis, obesity or skin problems. Both <a href="https://doi.org/10.11609/JoTT.o2620.1826-36" target="_blank">elephants</a> and orcas often have severe dental problems. Captive orcas are plagued by <a href="https://doi.org/10.1016/j.jveb.2019.05.005" target="_blank">pneumonia, kidney disease, gastrointestinal illnesses and infections</a>.</p><p>Many animals <a href="https://doi.org/10.1016/j.neubiorev.2017.09.010" target="_blank">try to cope</a> with captivity by adopting abnormal behaviors. Some develop "<a href="https://doi.org/10.1016/j.applanim.2017.05.003" target="_blank" rel="noopener noreferrer">stereotypies</a>," which are repetitive, purposeless habits such as constantly bobbing their heads, swaying incessantly or chewing on the bars of their cages. Others, especially big cats, pace their enclosures. Elephants rub or break their tusks.</p>
Changing Brain Structure<p>Neuroscientific research indicates that living in an impoverished, stressful captive environment <a href="https://doi.org/10.1016/j.jveb.2019.05.005" target="_blank" rel="noopener noreferrer">physically damages the brain</a>. These changes have been documented in many <a href="https://doi.org/10.1002/cne.903270108" target="_blank" rel="noopener noreferrer">species</a>, including rodents, rabbits, cats and <a href="https://doi.org/10.1006/nimg.2001.0917" target="_blank" rel="noopener noreferrer">humans</a>.</p><p>Although researchers have directly studied some animal brains, most of what we know comes from observing animal behavior, analyzing stress hormone levels in the blood and applying knowledge gained from a half-century of neuroscience research. Laboratory research also suggests that mammals in a zoo or aquarium have compromised brain function.</p>
This illustration shows differences in the brain's cerebral cortex in animals held in impoverished (captive) and enriched (natural) environments. Impoverishment results in thinning of the cortex, a decreased blood supply, less support for neurons and decreased connectivity among neurons. Arnold B. Scheibel, CC BY-ND<p>Subsisting in confined, barren quarters that lack intellectual stimulation or appropriate social contact seems to <a href="https://doi.org/10.1590/S0001-37652001000200006" target="_blank" rel="noopener noreferrer">thin the cerebral cortex</a> – the part of the brain involved in voluntary movement and higher cognitive function, including memory, planning and decision-making.</p><p>There are other consequences. Capillaries shrink, depriving the brain of the oxygen-rich blood it needs to survive. Neurons become smaller, and their dendrites – the branches that form connections with other neurons – become less complex, impairing communication within the brain. As a result, the cortical neurons in captive animals <a href="https://doi.org/10.1002/cne.901230110" target="_blank">process information less efficiently</a> than those living in <a href="https://doi.org/10.1002/dev.420020208" target="_blank">enriched, more natural environments</a>.</p>
An actual cortical neuron in a wild African elephant living in its natural habitat compared with a hypothesized cortical neuron from a captive elephant. Bob Jacobs, CC BY-ND<p>Brain health is also affected by living in small quarters that <a href="https://doi.org/10.3233/BPL-160040" target="_blank">don't allow for needed exercise</a>. Physical activity increases the flow of blood to the brain, which requires large amounts of oxygen. Exercise increases the production of new connections and <a href="http://dx.doi.org/10.1126/science.aaw2622" target="_blank">enhances cognitive abilities</a>.</p><p>In their native habits these animals must move to survive, covering great distances to forage or find a mate. Elephants typically travel anywhere from <a href="https://www.elephantsforafrica.org/elephant-facts/#:%7E:text=How%20far%20do%20elephants%20walk,km%20on%20a%20daily%20basis." target="_blank">15 to 120 miles per day</a>. In a zoo, they average <a href="https://doi.org/10.1371/journal.pone.0150331" target="_blank" rel="noopener noreferrer">three miles daily</a>, often walking back and forth in small enclosures. One free orca studied in Canada swam <a href="https://doi.org/10.1007/s00300-010-0958-x" target="_blank" rel="noopener noreferrer">up to 156 miles a day</a>; meanwhile, an average orca tank is about 10,000 times smaller than its <a href="https://www.cascadiaresearch.org/projects/killer-whales/using-dtags-study-acoustics-and-behavior-southern" target="_blank" rel="noopener noreferrer">natural home range</a>.</p>
Disrupting Brain Chemistry and Killing Cells<p>Living in enclosures that restrict or prevent normal behavior creates chronic frustration and boredom. In the wild, an animal's stress-response system helps it escape from danger. But captivity traps animals with <a href="https://doi.org/10.1073/pnas.1215502109" target="_blank">almost no control</a> over their environment.</p><p>These situations foster <a href="https://doi.org/10.1037/rev0000033" target="_blank">learned helplessness</a>, negatively impacting the <a href="https://doi.org/10.1155/2016/6391686" target="_blank" rel="noopener noreferrer">hippocampus</a>, which handles memory functions, and the <a href="https://doi.org/10.1016/j.neuropharm.2011.02.024" target="_blank" rel="noopener noreferrer">amygdala</a>, which processes emotions. Prolonged stress <a href="https://doi.org/10.3109/10253899609001092" target="_blank" rel="noopener noreferrer">elevates stress hormones</a> and <a href="https://doi.org/10.1523/JNEUROSCI.10-09-02897.1990" target="_blank" rel="noopener noreferrer">damages or even kills neurons</a> in both brain regions. It also disrupts the <a href="https://doi.org/10.1016/j.neubiorev.2005.03.021" target="_blank" rel="noopener noreferrer">delicate balance of serotonin</a>, a neurotransmitter that stabilizes mood, among other functions.</p><p>In humans, <a href="https://doi.org/10.1006/nimg.2001.0917" target="_blank" rel="noopener noreferrer">deprivation</a> can trigger <a href="https://doi.org/10.3389/fnins.2018.00367" target="_blank" rel="noopener noreferrer">psychiatric issues</a>, including depression, anxiety, <a href="https://doi.org/10.3389/fnins.2018.00367" target="_blank" rel="noopener noreferrer">mood disorders</a> or <a href="https://doi.org/10.1177/1073858409333072" target="_blank" rel="noopener noreferrer">post-traumatic stress disorder</a>. <a href="https://doi.org/10.1007/s00429-010-0288-3" target="_blank" rel="noopener noreferrer">Elephants</a>, <a href="https://doi.org/10.1371/journal.pbio.0050139" target="_blank" rel="noopener noreferrer">orcas</a> and other animals with large brains are likely to react in similar ways to life in a severely stressful environment.</p>
Damaged Wiring<p>Captivity can damage the brain's complex circuitry, including the basal ganglia. This group of neurons communicates with the cerebral cortex along two networks: a direct pathway that enhances movement and behavior, and an indirect pathway that inhibits them.</p><p>The repetitive, <a href="http://dx.doi.org/10.1016/j.bbr.2014.05.057" target="_blank">stereotypic behaviors</a> that many animals adopt in captivity are caused by an imbalance of two neurotransmitters, dopamine and <a href="https://doi.org/10.1016/j.neubiorev.2010.02.004" target="_blank" rel="noopener noreferrer">serotonin</a>. This impairs the indirect pathway's ability to modulate movement, a condition documented in species from chickens, cows, sheep and horses to primates and big cats.</p>
The cerebral cortex, hippocampus and amygdala are physically altered by captivity, along with brain circuitry that involves the basal ganglia. Bob Jacobs, CC BY-ND<p>Evolution has constructed animal brains to be exquisitely responsive to their environment. Those reactions can affect neural function by <a href="https://www.penguinrandomhouse.com/books/311787/behave-by-robert-m-sapolsky/" target="_blank">turning different genes on or off</a>. Living in inappropriate or abusive circumstance alters biochemical processes: It disrupts the synthesis of proteins that build connections between brain cells and the neurotransmitters that facilitate communication among them.</p><p>There is strong evidence that <a href="https://doi.org/10.1523/JNEUROSCI.0577-11.2011" target="_blank">enrichment</a>, social contact and appropriate space in more natural habitats are <a href="https://doi.org/10.1111/j.1748-1090.2003.tb02071.x" target="_blank" rel="noopener noreferrer">necessary</a> for long-lived animals with large brains such as <a href="https://doi.org/10.1371/journal.pone.0152490" target="_blank" rel="noopener noreferrer">elephants</a> and <a href="https://doi.org/10.1080/13880292.2017.1309858" target="_blank" rel="noopener noreferrer">cetaceans</a>. Better conditions <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5543669/" target="_blank" rel="noopener noreferrer">reduce disturbing sterotypical behaviors</a>, improve connections in the brain, and <a href="https://doi.org/10.1038/cdd.2009.193" target="_blank" rel="noopener noreferrer">trigger neurochemical changes</a> that enhance learning and memory.</p>