4 Things About Dogs

4 Things About Dogs

Paws/Pads

Dogs have a digitigrade bone structure (no heels on the ground) for speed and agility. Hunting breeds have more webbing to push off of regarding mud, snow and swimming. Racing breeds have 'hare feet' - where they have two inner toes longer than the outer ones for enhanced speed. Breeds from cold climates or for guarding may have 'cat feet', being more compact and rounder for stability and energy conservation.

Concerning paw pads, they have multi-layered cushioning against pressure - for bone plus joint shock absorption in rough terrain. It includes a very pigmented epidermis and thick puffy adipose tissue protecting the nerves and vessels in the dermal skin. The subcutaneous fat helps with springiness and helps insulate temperature too.

Paw pads can become more calloused over time, with exposure to rugged ground, reducing abrasion and inflammation for outdoor working breeds. Sedentary toy breeds have less developed skin thickness, being more susceptible to injury. Dogs also have an extra carpal pad, aiding traction involving digging, slopes, deceleration and skidding - they are sort of like brakes when the carpuses go down.

Countercurrent Blood Flow

Limbs/paws are prone to heat loss as they are the extremities furthest from the core, alongside less fur and a large surface area. Except, paws can still keep warm to withstand even -35 degrees celsius.

In the dermis, paw pad arterial blood is warmer than venous, with thicker material, higher pressure, more insulation deeper inside and blood coming down from the heart.

The arteries and veins pass each other, where heat transfers from arterial to cold venous blood returning from peripheries to the heart after chilly surface contact. Therefore, less energy gets expended to maintain core temperature.

Nose/Smell

The nose is sensitive to odour detection and assimilation, with wrinkles and dampness to entrap molecules, enforcing their predominant sense. Nare openings direct air to nasal cavities containing up to ~300 million chemo-receptors in breeds like bloodhounds, labradors or german shepherds with cilia projections to maximise air contact - at the very least 40x our smell intensity.

Separate nare slits lead to a bony compartment (like a specific olfactory area) that can retain air for odour build-up after closing the openings, promoting fixation intensity and interpretation of what humans can't smell, despite if the air is simultaneously exhaled from the main cavities - more primarily for breathing.

Dogs can naturally/get trained to smell things such as: tuberculosis, malaria, cancer, diabetes, gunpowder and drugs. Their smell is so acute they can actually distinguish the odours of twin humans.

Sniffer/tracking dogs are adept at sensing minuscule accumulations or dissipations in odour molecule concentration to follow a person's or animal's path along the ground - smell track results can get used in courts as evidence. With extensive training, sniffer dogs could perhaps detect scent molecules at one part per trillion, so they could somehow find an object, person or their way home from 20km away.

In addition, there is evidence that asymmetrical sniffing with each independent nare may concern different sensory pathways linked with each - perhaps for chemosignal emotional cues such as cortisol and adrenaline indicative of stress/fear. The left nare seems to be heterospecific, for example, human distress, whereas the right associates more with conspecifics. Both are probably still connected to the Jacobson's/vomeronasal organ for social interaction pheromones.

Eye Contact

Over thousands of years of development, dog domestication has likely transformed their facial muscle anatomy, primarily for expressive, inter-specific communication and attachment-based bonding with humans. Presently, dogs are able to comprehend communicative cues and human expression in ways other animals cannot.

Facial anatomy distinguishes the descended dog sub-species from wolves - in particular, the modified muscles responsible for intensely raising the inner eyebrow are present in dogs, but not wolves. Therefore, dogs gaze more frequently and strongly at humans. Reciprocated eye contact also encourages dogs to recognise when communication gets directed at them.

Initiated eye contact mutually invokes endorphins, with gratifying feelings of calmness enticing further gaze, eliciting subsequent behaviour exuded. Dogs can even utilise and maintain exaggerated eye contact. Exaggeration enhances attractiveness as a signal for help when they cannot resolve a problem alone. It is reminiscent of the expression humans produce when they are sad - the behavioural functions to induce human nurturing/parental instincts. No other movement makes the same effect, inferring its exclusivity through evolution.