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Doctor dog: how our canine companions can help us detect COVID and other diseases

Dogs love to sniff, and they’re good at it.



Renko Aleks/Shutterstock

While we humans generally experience the world through sight, dogs use scent to learn about the environment around them. What their nose knows is crucial for finding food, mates and safe spaces.

Our furry friends can also use their sniffing power to learn how people are feeling. For example, they can detect the scent of fear in human sweat.

Given this, it’s perhaps not surprising that pooches’ super-smelling skills can extend to monitoring human health – including, potentially, by detecting infectious diseases such as COVID. In a recent study undertaken in Californian schools, dogs were found to detect the virus with 95% sensitivity in a controlled laboratory setting and 83% in schools.

Read more: Human catches COVID from a cat – here's why this new evidence is not cause for panic

The olfactory capability of dogs far exceeds our own. Estimates suggest that dogs’ smelling ability might be up to 10,000 times better than ours, thanks to having more than 100 million scent receptors in their nose (compared to six million in people). Dogs can detect a wide range of different smells at much lower concentrations than humans or even hi-tech laboratory instruments – sometimes as low as at one part per trillion.

Interestingly, dogs use their nostrils separately. They start sniffing with their right nostril, and if the smell is familiar and “safe”, they switch to using their left nostril.

Dogs differ in the shape and size of their noses, of course, but all have an impressive ability to detect scent in a range of situations. And not only are dogs good at sniffing, they love to do it. Allowing dogs to sniff can actually improve their welfare and make them more optimistic.

Pandemic partners

Dogs have shown they can accurately identify a variety of infectious diseases via scent. For example, children infected with malaria parasites were successfully identified by dogs sniffing their foot odour. Dogs can also detect bacterial urinary tract infections, and gastrointestinal infections caused by the bacteria Clostridium difficle, which can be life-threatening in vulnerable patients.

Early in the COVID pandemic, it became clear that there was a need for extensive, real-time, accurate detection of infection. Respiratory infections cause the release of a range of substances that each have their own distinct smell.

Given dogs’ success in detecting other infectious diseases, the potential role of dogs as “lab partners” during the pandemic was quickly explored.

Initial research revealed that after just one week of training on COVID-specific odour, dogs were able to identify infections in bodily fluids from the respiratory system, correctly identifying positive cases 83% of the time. Once trained on respiratory samples, dogs were also capable of generalising their COVID detection skills to other bodily fluids, such as sweat and urine.

The potential for real-time screening with a high degree of sensitivity offers several advantages over traditional COVID testing methods, such as lateral flow and PCR testing, including cost and efficiency.

Screening by sniffing

In the recent study, two dogs already trained to detect the scent of COVID in the lab were taken into 27 Californian schools and completed 3,897 screenings, mostly among students, by sniffing their ankles and feet. For comparison and to check accuracy of detection, participants also undertook lateral flow tests.

After initial training, the dogs were detecting the virus in the lab with 95% sensitivity (correctly identifying positive cases) and 95% specificity (correctly identifying those who did not have COVID).

Screening people directly saw a slight drop in sensitivity to 83% and specificity to 90%. This is slightly lower than some estimates of the sensitivity and specificity of lateral flow tests, though their reported effectiveness has varied in different studies and between tests.

But even considering that the dogs made a small number of errors, given that screening could be completed within seconds, efficiency was high.

A woman sits with her dog on the couch.
Dogs have far superior olfactory skills compared with their human companions. MT-R/Shutterstock

In the same way that dogs routinely screen people for substances such as drugs or explosives as part of safety and security measures, they could offer effective medical screening services too. In high throughput environments such as schools or colleges, fast and effective screening would have distinct advantages.

However, all medical and health technology needs to be thoroughly evaluated for safety, cost and effectiveness, as well as any legal and ethical implications. Widespread health screening using dogs similarly requires ongoing review and careful consideration, while also ensuring the welfare of the dogs.

Doctor dog?

COVID is just one medical condition our canine companions could potentially help detect.

Along with infectious diseases, they have successfully detected certain forms of cancer in biological samples, the onset of epileptic seizures, and hypoglycemia (low blood sugar) in diabetes patients.

Read more: Were wolves dependent on humans long before they became man’s best friend?

Dogs and humans have lived together for thousands of years, and dogs have become constant human companions in many parts of the world.

The fact that they love to sniff, and are so good at it, has also made them important working partners in a range of roles. Using their innate skills to support human health and wellbeing through medical detection might be another way by which the human-dog relationship is deepened.

Jacqueline Boyd is affiliated with The Kennel Club (UK) through membership, as Chair of the Activities Health and Welfare Subgroup, member of the Dog Health Group and Chair of the Heelwork to Music Working Party. Jacqueline also writes, consults and coaches on canine matters on an independent basis in addition to her academic affiliation.

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Canadian dollar edges higher as retail sales rebound

Canada retail sales climb 2% The Canadian dollar has posted losses on Friday. In the European session, USD/CAD is trading at 1.3446, down 0.28%. Canada’s…



  • Canada retail sales climb 2%

The Canadian dollar has posted losses on Friday. In the European session, USD/CAD is trading at 1.3446, down 0.28%.

Canada’s retail sales jump

Canada’s retail sales rebounded in impressive fashion on Friday. Retail sales in July jumped 2% y/y, following a -0.6% reading in June and beating the 0.5% consensus estimate. On a monthly basis, retail sales rose 0.3%, up from 0.1% in June but shy of the consensus estimate of 0.4%. The good news was tempered by the August estimate, which stands at -0.3% m/m and would be the first decline since March. The Canadian dollar showed little reaction to the retail sales release.

The Bank of Canada doesn’t meet again until October 25th and policy makers will have plenty of data to monitor in the meantime. The BoC has been walking a tightrope that will be familiar to most central banks, that of trying to balance the risks of over and under-tightening. The difficulty in finding the right balance was highlighted in the BoC summary of deliberations of the policy meeting earlier this month.

The BoC decided to hold the benchmark rate at 5.0% after concluding that earlier rate hikes were having an effect and slowing economic growth. The summary indicated that policy makers were concerned that a pause might send the wrong message that rate cuts might be on the way. With inflation still above the BOC’s target, the central bank is not looking at rate cuts and stressed at the September meeting that rate hikes were still on the table and that inflation remained too high.


USD/CAD Technical

  • USD/CAD is testing resistance at 1.3468. The next resistance line is 1.3553
  • 1.3408 and 1.3323 are the next support lines

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Quantitative Tightening Is Not Biggest Threat To Global Yields

Quantitative Tightening Is Not Biggest Threat To Global Yields

Authored by Simon White, Bloomberg macro strategist,

The Bank of England’s…



Quantitative Tightening Is Not Biggest Threat To Global Yields

Authored by Simon White, Bloomberg macro strategist,

The Bank of England’s quantitative tightening program shows that unwinding central-bank bond portfolios, even with outright sales, need not be disruptive for markets. The greater risk for US and global yields comes from positive stock-bond correlations driving risk premia wider.

The BOE has been a pioneer and a thought leader in QT. While the Fed and ECB have only allowed bonds to run off naturally to help achieve their balance-sheet contraction goals, the BOE has sold gilts outright in addition to allowing bonds to mature.

So far, it has not led to any significant market disruption. This enabled the BOE Thursday to increase the pace of reduction in the Asset Purchase Facility (APF) from £80 billion last year to £100 billion over the coming 12 months from October (while holding Bank Rate steady). As colleague Ven Ram also noted, the schedule of maturing bonds next year allowed the bank to keep gilts sales unchanged from last year while increasing the total amount of the APF’s decrease.

The QT watchwords from the bank are “gradual and predictable.” If gilt sales are conducted in such a way, then market disruption should be minimized. The chart below shows the BOE’s own assessment of the impact of bond sales on the market.

The BOE estimates that of the ~40 bps of term-premium increase since the MPC voted to begin QT in February 2022, about 10-15 bps comes from QT specifically – small in comparison to the overall rise in yields since that time.

QT or bond sales, though, are not the most critical risk facing bond prices in the current cycle. Rising and now positive stock-bond correlations threaten to lead to a structural rise in bond risk premium, and lower prices. The correlation is now positive in the US, Japan, and the UK.

In a positive stock-bond correlation world, bonds lose their portfolio-hedge and recession-hedge capabilities, and thus become less sought after. The penny has not fully dropped yet, but the negative term premium for bonds is increasing, and is prone to rising much higher as they become less desirable.

Yields of developed market countries are biased structurally higher, but QT is unlikely to be the culprit. Instead, it allows central banks to reload their capacity for a future time when they may need to restart quantitative easing, in order to stabilize the market from sharply rising term premia.

Tyler Durden Fri, 09/22/2023 - 09:10

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How ducks, geese and swans see the world – and why this puts them at risk in a changing environment

Our airspace has only started to become cluttered recently – many birds are struggling to navigate through it.




The blue duck (Hymenolaimus malacorhynchos) is a species endemic to New Zealand. Graham Martin, CC BY-NC-SA

Each year, millions of birds fly into power lines, wind turbines and the other man-made structures that litter the open air space. These collisions frequently result in the death of birds and, if power systems go down, disrupt our lives and pose financial challenges for power companies.

Numerous bird species, including macaws in Brazil, geese and swans in the UK, and blue cranes in South Africa have been found to be susceptible to collisions with power lines. But any flying bird can fall victim to such a collision.

In some places, these collisions happen so often that they can jeopardise local populations of endangered species.

But birds are highly evolved flying machines. They can fly in tightly packed flocks that weave and turn to our delight and wonder. So why do they fly into things?

According to our latest research, the answer lies in how they see the world. We found that looking directly ahead is simply not that important to many species of duck, geese and swans.

A flock of swans flying past a power line.
Seeing what’s ahead is not that important to many species of duck, geese and swans. Marijs Jan/Shutterstock

How birds see the world

Exploring the reasons behind why birds are victims of collisions has led to new ideas that challenge our fundamental perception of what birds are. In the past, scientists have described birds as “a wing guided by an eye”. This implies that flight has been central to moulding bird vision throughout their evolution.

But now it is safe to conclude that a bird is instead best characterised as “a bill guided by an eye”. Rather than flight, the main driver of the evolution of bird vision has been the key tasks associated with foraging, in particular detecting food items and getting the bill to the right place at the right time in order to seize them. Alongside the detection of predators, this is the task that bird vision has to get right day in, day out.

Birds differ in how much the view from each eye overlaps (called the binocular field of view). The more the eyes look straight ahead, the more the view from each eye will overlap – much as human eyes do – thus broadening the binocular field. For a bird such as a duck, with its eyes positioned high up on either side of the head, the view from each eye will be very different (with smaller binocular field).

We measured binocular field size across a broad range of 39 species of duck, geese and swans. We found that the key driver of diversity in vision between species is their diet and how they forage for food.

Birds that primarily use their vision to locate foods such as seeds, or selectively graze on plants, tend to have broader binocular fields.

However, the binocular fields of species like mallards and pink-eared ducks are much narrower. These birds rely less on their eyes for foraging and more on touch cues from their bills. The vision of birds like these instead provides them with a comprehensive view of the region above and behind their heads.

Birds certainly need to have some visual coverage in front of them. But with eyes placed high on the side of the head, resulting in a very narrow binocular field, they are restricted to retrieving rather scant detail from the distant scene ahead. What matters to them more is placing their bill accurately at a close distance and seeing who is coming at them from the side or from behind.

Two pink-eared ducks in water.
Pink-eared ducks rely less on their eyes for foraging. Imogen Warren/Shutterstock

This finding is not confined to ducks, geese and swans. It probably generalises to all birds, except perhaps some owls (which have more front-facing eyes and rely upon sound to locate prey). The great majority of birds are therefore vulnerable to collisions.

However, it is larger birds like geese, swans and bustards that face real problems. Their restricted forward vision is compounded by flying fast and being unable to change direction quickly. These birds also often fly in flocks, and at dusk and dawn when the light level is lower.

Warning birds of hazards ahead

Understanding the vision of birds from the perspective of foraging and predator detection improves our understanding of what causes collisions. But, more importantly, it allows us to do something about it.

We must not assume that a bird’s view of the world is the same as ours. We are specialised primates with eyes on the front of our heads, and we see the world in a very different way to birds, not only with respect to visual fields but also acuity and colour vision. So, we must try to take a proper “birds’ eye view” of the problem.

Birds are also flying fast. But, as they do so, they are taking in only gross information of what lies ahead – much as we do when driving our cars. As with car hazard warnings, it is necessary to alert birds using markers that may seem excessive.

Birds that are vulnerable to collisions have evolved to fly in airspace that only recently has started to become cluttered. To be clearly visible to a bird, especially to species like ducks and geese, devices that warn birds about hazards ahead must be large, highly contrasting and produce flicker.

When marking hazards, there is no place for subtlety.

Jenny Cantlay received funding from NERC and the RSPB for her doctoral research on avian vision whilst at Royal Holloway University.

Graham Martin does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

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