Canine Physiology

Copyright © 2018 DSPCA Dog Training Academy

published by the Dublin society for the prevention of cruelty to animals www.dspca.ie

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First printing, September 2018

Contents

Introduction

Body

Gait

Walk

Amble

Pace

Trot

Flying Trot

Canter

Single Suspension Gallop

Double Suspension Gallop

Dwarfism & Giantism

Head Shapes

Dolichocephalic

Mesaticephalic

Brachycephalic

Other Head Shapes

Nose

Jaws and Teeth

Tail Shapes

Eyes & Sight

Range of Vision

Light Receptors

Motion Detection

Nose & Scent

Ears & Hearing

Outer Ear

Middle Ear

Inner Ear Ear Types

Paws

Coats

Colorings

Texture

Alterations

Introduction

Aims of Module

By the end of this module, the learner will be able to: • Identify the various components of a dog’s body • Understand the mechanism by which dog shapes vary • Itemize the various distinctive markers of the different types of dogs • Discuss the processes of docking and cropping

Having both descended from the same mammalian origins, and with traits that go back much further than that, it is no surprise that most of the organs, skeletal structures and even rough placement of components can be mapped from h u m a n s to dogs. There are of course s o m e exceptions, but we are basically made up of the same things, as we shall see in this mo d u l e . The s p e c i f i c s of actual s i z e , r e l a t i v e size, positioning and limitations of the different parts vary widely not just with other species but within species as well. Due to our influence with the dog through its evolution it is the species most varied in physical appearance anywhere in the animal kingdom.

Despite our meddling, the dog still retains much of its core features from its grey ancestors, specifically the underlying predator at- tributes. A core skill required for a predatory life is manoeuvrability. Naturally this is, in this day a n d a g e , heavily dependent on breed and type of dog, the skeleton itself, disregarding deformities of over breeding, is designed to allow for just that. For example, the shoulder blade, or scapula, is attached to the rest of the skeleton by four muscles that allow for maximum range of movement of the front quarters of the dog. Similar to cats, however, not to the same extremes, dogs have very flexible spines to go with these freely moving forelimbs. A flexible spine allows for larger swings of limbs to produce a longer stride when in a dead run. Additionally, in the front portion of the body, there are other alterations, such as a locked radius and ulna, the two bones of the forearm, w h i c h allow for extremely rapid direction changes without damaging the bones themselves as these are the main force bearers in such a direction change.

In addition to skeletal efficiencies that are rooted in the dog’s predatory history, their senses have retained their heightened abilities as well. Dogs are much more reliant on scent than they are eyesight, and have even adapted to be able to smell u n d e r w a t e r . Their ears can swivel towards a sound independently of each other and are thus not only able to pinpoint specific sounds very well, they are also able to track multiple sources of sounds at once.

Unlike humans, dogs do not have sweat glands in their skin. The only p l a c e t h e y have these is on the pads of their paws. For r el i ef from heat, dogs must also pant. This allows the tongue to hang out, which also expands in this state for greater surface area, and the saliva provides a cooling effect on evaporation.

Body

Figure 1: Belgian Malinois with Stop main body parts labelled. Each The point at which angle c hang e b e t w e e n the muzzle and eyes are described below. is measured on the

Nose Dog’s noses can come in either coloured, a butterfly nose, or flesh coloured, a dudley nose

Muzzle The extended shape of the skull from the nose back to the cheeks

Flews The canine equivalent of upper lips

Sternum Eight bones that form the floor of the chest

Forearm Lower portion of the front legs, between the wrist and elbow

Wrist As with h u m a n wrists, these are articulated to allow movement, however only in one of three planes, unlike ours t h a t allow for movement in two planes

Carpal Pad Can be used for additional traction on steep slopes

Elbow Allows for motion in one plane, just as with humans

Chest Contains many of the vital organs, just as with other species

Stomach/Belly Contains digestive, and reproductive organs

Stifle The equivalent of the human knee, this is a very complex joint that can cause issues in many toy breeds

Lower Thigh The part of the hind leg beneath the knee to the hock

Pastern Portion of the leg between the Hock and the foot and can be com- pared with the bones in human hands and feet, disregarding the fingers

Hock Corresponding to a human ankle, the hock only allows movement in one plane rather than multiple

Tail The dog’s tail can come in a range of styles and shapes to be dis- cussed later

Upper Thigh The part of the dog’s leg situated above the knee on the hind leg

Croup Otherwise known as the rump, is the part of the back that is between the loins and the tail

Hip The hip is a joint very similar to our own apart from its orientation

Loins The loins run either side of the spine from between the false ribs and hipbone

Shoulder Connected by 4 strong mu s c l es allowing for extremely free move- ment of the front limbs

Withers A ridge between the shoulder blades, typically the tallest point on the body a n d a standard measurement spot for determining the height of an animal

Cheek Figure 2: puppy head showing the occiput Expanse of flexible skin covering the rear opening of the jaws among other features.

Occiput Pointed bone at the top of the head, more prevalent in some breeds than others

Gait

A dog’s gait is a description of how it moves. While it is, for some breeds, strictly specified in breed standards what sort of gait is required for a dog to have, understanding gaits is much more important for understanding whether there are any issues with our dogs’ movements. Gaits cover a number of different speeds of motion, just as with . There are eight types of gait, each of which we shall look at below.

Walk

The walk is the slowest gait that we look at. It involves having only one foot off the ground at any one time, with the other three always in support of the body. Each foot is lifted and replaced in a specific sequence. The w a l k can be broken down as right-rear, right-front, left-rear, left-front, or RR, RF, LR, LF as short hand.

Amble

The amble is typically a transitioning gait between walk and other gaits. In the same sequence as the walk we, at least at times, have two legs off the ground. This is usually the legs on the same side of the body as we move from the motion of the rear to the front legs. So as the right-rear leg is about to land, the right-front lifts off.

Pace

The pace is not a particularly natural gait. It is usually used by puppies who are not strong enough for some of the other gaits yet, i.e. the trot, or by tired dogs that need to conserve energy. In this gait, two lateral legs move together, that is right-rear and right-front or left-rear and left-front. This is what is known as a two-beat gait, that is since two legs move together at all times there are only two instances when legs hit the ground, the left ones together or the right ones together.

Trot

The trot is another two-beat gait, however this time opposite legs move together, that is rear-right and front-left, and then rear-left and front- right. This is very similar to trot we know from horses. Depending on the dog it can be quite a bouncy affair.

Flying Trot

The flying trot, or suspension trot is quite a fast gait and can often look like the dog needs to break into a canter or gallop. At it has the same sequence of movements as in the standard trot but at the extremes of each swing all four legs are off the ground.

Canter

The canter is a very natural gait, often used for travelling long distances. Most versions are actually slower to the trot but allow for a more natural transition to a full gallop than from the trot. The gaits we have looked at so far have been very symmetrical, being even-numbered beat gaits. The canter, however is a three-beat gait and therefore is dependent on the leading foot of the dog. Which front foot leads defines which side everything happens on. If, for example we have a right-lead (i.e. the right leg leads), the gait progresses as: rear-left, rear- right and front-left, front-right.

Single Suspension Gallop

This is back to a four-beat gait but is really just the canter wi t h a decoupling of the diagonal unison in the middle. This typically works out to right-front, left-front, right-hind, left-hind. The dog is airborne or ’in suspension’ once per stride, just after lifting up with the second front foot.

Double Suspension Gallop

The most natural way to think of this gait is to recall how a runs while coursing. In this the dog is airborne twice per stride. At one half of the stride, the front legs are fully extended out front and the rear legs out the back and at the other half of the stride, the front legs are folded back past the back legs and the rear legs have over taken the front legs, again achieving suspension. This is the gait where the flexible spine comes into play to allow the folding and extension of the body to allow for such extreme swinging of the legs.

Dwarfism & Giantism

A particular irregularity in development allows for not just dwarf and giant breeds of dogs but for the whole array of different shapes, sizes and combinations thereof. That process is neotenisation. This allows for parts of the body to continue growing when other s have already stopped. For example, when the whole body keeps growing past the typical growing period, you get a giant breed such as a , on the other hand, if the body stops growing earlier and allow the organs to mature but at a smaller size we get a , for example.

All of the different shapes and sizes can be accounted for by this process. Additionally, all of the different shapes of the body are actually different development stages of a typical wolf foetus either paused or extended specifically for that component. For example, the nose of a , being short as it is, can be accounted for by the developing skull of a wolf foetus before the muzzle extends out from the skull.

These extrema also impact on other developmental factors, such as age of sexual maturity, adolescence, and even possibly the period in puppies where inquisitiveness overrides fear. Leading theories suggest that these changes are coded genetically and implemented via hormone production, retention and quantities. This neotenisation effect can also help to account for the differing behaviours between or even many other types of mammals and dogs, in that they continue to play into adulthood. With dog’s adulthood is narrowly defined as any time past the onset of sexual maturity. We will discuss a particular study that goes further i n t o these variations in the next module on breeds and types.

Head Shapes

There are three core shapes that form the basis of all dog head shapes. Naturally variations of each of these allow for the huge variety of head shapes seen throughout the dog family. Head shapes are defined in terms of what is called the cephalic index. This index compares the maximum width to the maximum length in a horizontal plane, we will not get into the formulaic values here. Those t h r e e shapes a r e : Dolichocephalc; Mesaticephalic; and Brachycephalic.

Dolichocephalic Figure 3: The three main h e a d shapes in dogs. The first is a These head shapes are epitomised by and long slender head. These are which demonstrates typically very delicate-looking faces. Dogs that demonstrate this face a Dolichocephalic head shape, the shape are , Afghan Hounds, your typical and even the second is an English cocker rough collie. which illustrates the Mesaticephalic, and thirdly the Boston s h o w s a Brachy- cephalic head shape.

Mesaticephalic

The Mesaticephalic head shape is more wedge shaped than long. That is a broad s k u l l with a slenderer muzzle. Typical dogs in this category are English cocker , the chow chow, and the .

Brachycephalic

Brachycephalic heads are, relatively speaking, broader and shorter than their counterparts. There are extremes in any of the categories, but the one that would likely stick out most is the pug. Illustrative examples of this head shape are the , Newfoundland, and the Shar-pei.

Other Head Shapes

A few other shapes are the, less than endearingly named apple-head, the dish-faced, and the down-faced. As suggested by the title, apple-headed dogs have a flat topped r a th er than round head. An example of this would be the Chihuahua. The dish-faced type has a nasal bone that is higher at the nose than at the stop. This can be difficult to see in many breeds but a good e x a m p l e would be the . Finally, the down- faced dog has a face basically opposite to that of the dish-faced, where the muzzle is slightly turned downward, a very notable example being t h e bull t e r r i e r , a less well k n o w n one would be the Russian Figure 4: The Russian is borzoi. a subtle but clear example of the down-faced head shape. Nose

A quick aside to mention a dog’s nose. These can be solid-coloured, black or brown, for example, or they can be flesh-coloured. There are cases of a mixture of these. An important thing to note is that leaving a skin-coloured nose unprotected can lead to illnesses such as skin cancer in dogs, so it is important to add a bit of sunscreen in good weather.

Jaws and Teeth

Adult dogs typically have approximately 42 teeth; variations depend on breed. Some of the smaller breeds have mouths too small for the typical number of teeth and as such there can be instances of double rows of teeth where either there are too many adult teeth to fit beside each other or the adult teeth did not push through directly under the puppy teeth and so the puppy teeth did not fall out. These teeth are divided into incisors, canines, premolars and molars. The functions of each of these teeth are quite similar to those in humans but with more pronounced effect. The incisors are used to bite into something, or nibble at soft food or an itch. The canines are the extremely effective teeth for grabbing and puncturing a target. They are also adept at ripping. Beyond those are the premolars, these are used for sheering a piece of meat from a larger mass. Finally, at the back are the molars, these are used for grinding up and chewing a meal, or toy.

Figure 5: Side view of the top portion of a dog skull showing

the differences between the

incisors, canines, premolars and molars.

Bite inhibition in puppies is a very important skill that they learn. Just as with a bark, we do not want to teach a dog right out of the box to never bite, they need to learn how to control th e force on their jaws so as not to damage in the event that they get scared over something in the future and redirect a fearful bite on an unsuspecting arm. We would rather they knew how to avoid damage early t h a n potentially get into serious trouble when something scary happens. It can be very difficult to take your time with t h i s training, as puppy teeth are extremely sharp. Researchers suggest that this is the case to precisely help with learning how to safely inhibit their biting when they are young and still playing with litter mates. At these ages their jaws are not particularly strong so if their teeth were rounder, like those of an adult, they would not bite hard enough to hurt their play mates and hence not learn what is too much pressure.

Tail Shapes

There are a number of tail shapes and an analysis of dog breed standards will identify quite a few more than we will mention here. The following list is not an exhaustive list of tail shapes.

Saber The saber tail is carried in a slight curve which can be raised to various heights, this is best illustrated in the typical .

Corkscrew A corkscrew tail is one that is twisted in a curl, typically quite a tight curl. Some breed standards give a preference for a double corkscrew which is a tail twisted twice around. This is most commonly seen in . One of the main issues with corkscrew tails is that to form such a bend in the tail, (extended spine), the vertebrae need to be more trapezoidal in shape than rectangular, thus causing some difficulties with the spine.

Odd The odd tail, unfortunately named, is quite a rare tail shape. This tail has a curl in it but remains long with the remaining length of the tail typically hanging down over the dog’s back. A prime example is the .

Sickle The sickle tail is carried, typically high, in a semi- circle, such as with a husky.

Bob The P emb rok e Welsh Corgi is one of the few dog b r e e d s w i t h a naturally short to non-existent tail. They have been bred for this characteristic rather than docking the tail. Docking will be discussed later in this module

Squirrel The squirrel tail is kept long and his held high along the length of the back, rather than dropping down the side such as the odd tail above. The most famous example is likely the Pomeranian.

Eyes & Sight

The canine eye is for the most part, the same as the human eye in structure. The main components are the same. The iris, cornea, pupil, lens, retina and optic nerve. Dogs have eyelashes just like us, which can get turned in. They

also have a third eyelid that helps to keep the eyes moist and clean, particularly for those dogs with looser skin. The differences come into play

when we start talking about the light receptors. There are two types of light receptors in any animal’s eyes, cones and rods. Cones are responsible for distinguishing colours whereas rods are responsible for identifying the

differences between light and dark.

Figure 6: The ba sic sha pe of a canine eye is the same as that of a human. The differences arise in the light receptors.

While a dog’s eyes can usually take care of themselves there are a few th in g s to keep an eye on. In b r e e d s w h e r e t h e eyes bulge, accidental impacts with everyday objects can be a possibility. This can 1 We will discuss some do some damage to the surface of the eye and the surrounding support common eye problems when structures. The cornea in particular is quite a vulnerable structure, it is we approach the module on designed to act as a guard and protection for the eye and so while canine health & wellbeing. designed to take some punishment, it is therefore more likely to get damaged1.

Range of Vision

Dogs have a much wider range of vision than humans due to the placement of their eyes on their heads. Their eyes are set further to the sides than our own. This means that they have greater vision to each side of their head than we do. The typical range of view for a human is about 190°. For a dog, it is 250°, that is an extra 60°.

Right Eye View, Monocular vision – 145°to 30° Figure 7: Range of view of the

typical dog, top down view looking

to the left. Diagram shows the full field of view in dark or- angel

the overlap of the binocular region

in mid orange, and each of the Full Range of View – 250° monocular fields in light orange Binocular Vision on either side. Line of Sight

30°each side

Left Eye View, Monocular Vision – 30°to 145°

Both humans and d o g s h a v e portions of their field of view that are binocular and mo n o c u l a r , that is portions where b o t h eyes can see the world and portions where j u st one eye can see, respectively. The d i f f e r e n t face shapes d e s c r i b e d above do impact on the range of binocular and monocular vision a dog can have, purely down to whether the nose gets in the way or not.

Light Receptors

As mentioned earlier, there are two types of light receptors in animal eyes, cones and rods. Cones are responsible for seeing c o l o u r s and rods distinguish light and dark. There are different types of cones for different colour ranges. Humans, for example are trichromatic, that is we have three different types of cones for red, green, and blue-violet colour detection. Dogs, on the other hand are dichromatic. Dogs cannot distinguish between reds and greens. Their colour spectrum is made up of yellows, blues an d greys2. In addition to having only h a v i n g dichromatic vision, dogs also have less actual cones as well as different types of cones so their ability to see detail is reduced significantly.

2 It might be time to reconsider all of While they have less cones than us, they do have more rods in their those red dog toys that we assume stand out in the grass so well. eyes than us. This allows them to see more clearly in dim light, that is, their night vision is far superior to ours. Due to this dogs are much better with an overall silhouette for some training techniques and can spot distant objects only when they are near the horizon. In addition to having more rods in their eyes, dogs also have larger pupils which allow more light into their eyes in dark situations. There is a mirror-like structure at the back of the eye called t h e tapetum. This structure bounces light entered back at the retina a second time allowing for a greater chance to collect the light.

Motion Detection Figure 8: Differences in dog vision to our own. The first image Dogs can see motion much better than they can see stationary targets. shows the original colour image This is quite important in some training techniques, as we shall see in a later that we see. The middle image module. If a target stays downwind from a dog and stays very still, chances shows just the differences in colour are it will not be noticed, however, if that same target stays downwind but between what a dog sees and tries to make a run for it, it will almost certainly be seen. A dog’s what we see. The final image sensitivity to motion is particularly noticeable in breeds trained as guard shows the reduced acuity do to the dogs. These dogs are very sensitive to motion, and often are bred in such lessened number of cones. a way t h a t not only do they notice it but are startled f r o m it. This can create an anxious reactivity due to being so aware of this motion. With a n y dogs, particularly those less well socialised, speed and abruptness of motion must be taken into account so as not to provoke any unwanted fear or reactions.

Nose & Scent Just as we are visual animals, dogs’ primary sense is their sense of smell,

with auditory abilities coming in a close second. Studies have shown that when an object gets too close for a dog to visually focus on it they Scent Receptors will switch to their sense of smell to understand what it is getting so close. This lowered reliance on visual ability is extremely Human 5 million 125 million advantageous when tracking in dim light or heavy undergrowth. The 300 million shape of the nostrils and the method by which they sniff in air creates eddies in the air itself, mixing up the scent particles as they are inhaled. Independent of breed, size, or shape, dogs typically sniff at a rate of five times per second. The entire extent of a dog’s muzzle from the external n o s e to the stop contains the myriad of tools used to detect and analyse different scents. As scents are taken in through the nostrils, they are sent down two separate passages, one for each nostril. They are analysed independently and finally mixed back together again at the back of the throat. This allows for the extra inhaled air to be passed out through the mouth. There is a huge difference between the number of scent receptors between humans and dogs. Naturally, the number of scent receptors is dependent on muzzle shape as well as breed. For example, a would have much fewer receptors than a , however their ability to scent would still be significantly better than a human’s. We have approximately five million scent receptors whereas dogs can have up to three hundred million.

Nasal Cavity There are two cavities, one for each nostril that each extend back from the external nose. The olfactory receptors in the nose extend through the entire cavity. There is another chamber called the vomeronasal organ or Jacobsin’s organ.

Jacobson’s Organ The olfactory receptors in this organ are different from those in the main nasal cavities. The Jacobson’s organ consists of two large fluid filled sacks. Crucially, these sacks are accessible through the roof of the mouth, wh e r e there is an opening in the bone of the skull but with a layer of skin as a protection. This organ allows dogs to smell tastes.

Hard Palate A hard plate of bone in the skull in the roof of the mouth.

Sinuses The sinuses have a number of functions, the first is to add moisture

Figure 9: A labeled diagram of the typical canine scenting organ.

to the air that has been taken in which allows for capture of scent particles. Additionally, it provides resonance chambers for the vocals.

Epiglottis This allows for redirection of food down the oesophagus rather than the trachea.

Oesophagus Otherwise known as the food pipe. This is the path which food travels to get to the digestion system. This must be kept separate from the respiration system when eating.

Larynx This helps in protecting the respiratory system from food along with containing the vocal chords.

Trachea The trachea is the direct connection with the lungs. This must be kept void of food particles at all times.

Vocal Cord These a r e skin flaps a c r o s s t h e larynx. They open a nd c l o s e to different extents and vibrate when air passes to create sound.

Ears & Hearing

The main components of a dog’s ear are quite similar to our own, despite the differences in our hearing abilities. Humans can hear from about 20Hz up to between 12,000 and 20,000 Hz. Dogs on the other hand can hear from about 40Hz up to approximately 60,000Hz. Just as in humans this varies with age but it also varies depending on breed. Also, just as with humans, dogs can begin to lose their hearing as the get older, and it tends to be the higher frequencies that they lose first.

Outer Ear

Ear Pinna This is the outer part of the ear, the visible portion that sits outside the head. This can also be called the auricle. It helps with capturing, amplifying, and funnelling sound into the auditory canal.

Ear Canal The tube running from the pinna to the middle ear.

Figure 10: The structure of a dog’s ear

Middle Ear

Ear Drum The ear drum’s main function is to convert air-based sound waves to vibrations in a fluid. They first pass through the ear ossicles, a collection of bones that capture the sound once passed through the ear drum.

Ear Ossicles A collection of small bones that transmit sounds passed from the ear drum through to the cochlea in the inner ear.

Eustachian Tube This tube connects the auditory system to the nasal system.

Inner Ear

Vestibular Organ This organ provides the largest contribution to the sense of balance and s p a t i a l orientation. The semi- circular canals on the diagram handle rotational motions and the linear otolith organ translates.

linear motion

Cochlea This spiral bone has a number of hollow chambers and channels running through it that allow for translation of the sounds from bone (i.e. solid) to the auditory nerve.

Auditory Nerve This carries the auditory signal directly to the brain.

Ear Types

The pricked ear shape is the closest to the original grey wolf ear shape. This is held tall and is a general triangular shape. These are typically seen in huskies, German shepherds and the , for example. Other ear shapes can be bred for but also seem to be a side effect of the domestication process, purely since t h e domestication process is not selecting specifically against it.

Erect There are several ear types that could be considered erect. The bat ear, prick ear and natural are all held erect. There are even partially erect types of ears that begin to fold near the top but are otherwise held erect.

Button Typically button ears are similar to the semi-erect ear but are usually smaller with a larger proportion of the ear folded over on itself. The pug provides a good example of this ear type.

Rose The rose ear is a small drop ear with a backwards fold. This can be seen in the bulldog.

Pendant Also called a drop ear. This ear type folds close to the head to allow it to hang d o wn the side of the head. Many hounds or gun dogs have these ears, for example the Bloodhound.

Paws

A dog’s paw has four toes with a pad on each. Each of these pads are load bearing. On the front limbs the central heart-shaped pad is called the metacarpal and on the hind limbs this pad is called the metatarsal. There is a further pad higher up on the forelimbs called the carpal pad.

As mentioned previously, this is theorised to be for traction on steep slopes.

Dogs will always have a dewclaw on the front limbs and sometimes on the rear. Some of these claws may be poorly attached and require early intervention or maintenance. While not in heavy use, dewclaws are useful in grasping something for chewing or gnawing. This claw must be trimmed just as with the other claws as it is not a dead claw. If it is not trimmed it can grow into the pad causing severe discomfort and potentially infection.

Coats

As much as with size and shape in dogs, their coats vary substantially from breed to breed and even within breed there can be significant differences. The original grey wo l f h a s what is called a double coat which is comprised of a soft insulating undercoat and an overcoat that is coarser. Many modern breeds have just a single coat rather than the heavy undercoat as well. This allows dog to live more comfortably in warmer climates. The single coat or outer coat when considering a double coated dog is typically moisture repellent. There are also the few breeds that are mostly or completely hairless.

Colourings

There are a very wide variety of coat colourings throughout the breeds. Some have a single coloured coat, some contain multiple colours. Different breeds may come in only one colour, some may come in any one of three or more variations. Some listed colours will be different on the different breeds.

Red The difference in the reds can be best summed up by looking at breeds such as the Irish red setter, the ruby cavalier and the red chow chow. Each described by their vibrant colouring as red, these reds are very different from each other. It should be noted that not all reds will be vibrant.

Cream Cream is the typical main c o l o u r of the lighter coloured Golden Retriever, for example. This is not to be confused with the typical fawn or silver colouring of the pug.

Gold Gold is interpreted in several hues. The golden retriever, golden cocker spaniel and yellow dachshund all look quite different but fall under the same colour banner.

Chocolate, brown & liver One of the most distinctive chocolate coloured dogs is the chocolate . Similarly, the German short-haired pointer has liver patches as its most distinctive set of colours.

Black A lot of breeds come in black, however not so many come in a solid black. It is has become quite common to find English cocker spaniels in a full black. One of the dogs, the Groenendael, mostly comes in a solid black. A very famous black dog, currently, would be the Portuguese water dog.

Fawn The stereotypical two coloured pug’s main body colour is usually a fawn colour. One of the other Belgian shepherds, the Mallinois, also has a fawn colouring with a black face.

Blue Blue colourings are specific to some breeds such as the Weimeraner or the Kerry blue. It can come in a more dappled version in the roan blue colourings. Rarely, one can come across a tan and blue German shepherd.

White Many of the companion dogs of recent generations come in white colours, such as the Maltese. A particularly well known white coated dog is the Samoyed.

Grey The most notable example of a grey dog is the family of . have been known to come in a silver colouring which manifests as a lightened black.

Texture

Dogs coats come in a number of different textures which all require different grooming techniques and tools.

Hairless Hairless coats can be completely without hair or include some tufts of hair on the crown of the head and extremities, such as the Chinese crested.

Short Short coats a r e quite s t a n d a r d , the most n o t a b l e would be the Labradors, but also includes the .

Curly Curly coats can come in either tight dense curls or looser varieties. The most notable curly dog would be the .

Corded Corded coats are often compared to human dreadlocks. The hair becomes matted into long cords. This has a defensive application.

Long and straight Long and straight fall typically into the companion dog categories, such as the Maltese.

Long and fluffy A long fluffy coat is epitomised by the .

Alterations While we will not get into an in-depth discussion of the rights and wrongs of what people do to their dogs but two physical alterations that are made to dogs a r e worth a few moments of our time. The first of these is the practice of tail docking. As of 2014 tail docking is illegal in Ireland. Docking is the process of removing the dog’s tail by surgical Figure 11: A Doberman pinscher or other methods. It is still permitted under certain strict conditions, that has had its tail docked and such as for medical purposes or for lawful hunting work. No cosmetic ears cropped. tail docking may be performed. Legal tail docking is done under anaesthetic in a safe and pain freeway. An owner of a dog that has been legally docked must have the required paperwork stating that the procedure was indeed lawful. Additionally, dew claw r e m o v a l cannot be done for cosmetic purposes. It may only be performed by a veterinary practitioner for medical purposes. Finally ear cropping is also illegal in Ireland. Ear cropping is the process of shaping the ears surgically and typically involve a stage where the ears are held upright in a cast bridged together to train them to stay upright.

List of Figures

1 Labelled image of body components of Belgian Malinois. Original image acquired from Bigstock images as per copyright information

2 Beagle Puppy labelled head showing occiput, among other features. Original image acquired from Bigstock images as per copyright information

3 Rough collie, English cocker spaniel and showing the three main head shapes. Original image acquired from Bigstock images as per copyright information

4 Russian borzoi displaying the down-faced head shape. Original image acquired from Bigstock images as per copyright information

5 Image identifying the main teeth types in a canine skull. Original image acquired from Bigstock images as per copyright information

6 Basic components of an eye. This image is from the Wikimedia Commons which is a freely licensed medial file repository.

7 Graphic demonstrating the typical field of view of a canine. This image was created u s i n g the package in L A T E by the author.

8 Array of three images showing the differences between a dog’s vision and our own. The original image was taken by the author of this document and edited via the image manipulation tool

9 A labelled diagram of the typical canine scenting organ. This is an image from the Wikimedia Commons, which is a freely licenced media file repository.

10 The structure of a dog’ ear. Note: This image is licensed under the Creative Commons Attribution 3.0 Unported license.

11 A Doberman pinscher with a docked tail and cropped ears. This image was acquired from Bigstock photos as per the details in the copyright page.