Dogs come in all sorts of different shapes and sizes, there’s the perfect dog for everyone. I guess that’s why we love them all so much. Dog head shapes are particularly fascinating. They actually help us to understand what some of our dogs strengths might be!
The cephalic Index:
The Cephalic Index describes this variation in dog head shapes. It’s a scale for comparing the width of a dog’s head relative to its length. Breadth is measured across the widest part of the head and length is measured from the back of the skull to the tip of the nose.
Dogs with a low cephalic index have long faces and dogs with a high cephalic index have flat faces.
There are 3 main types of dog head shapes, brachycephalic, mesocephalic, and dolichocephalic.
Dolichocephalic have extremely long skulls with long and slender noses. Examples include Greyhounds, Dachshunds, Great Danes, etc.
Brachycephalic are short nosed, flat faced breeds whose skulls are broad. Examples include Pugs, Boxers, Bulldogs, etc.
Mesocephalic have an intermediate length and width of the skull. Examples include Beagles, German shepherds, Labrador, etc.
This Greek word means ‘long’ and ‘head’ which seems logical. These dog’s have a skull containing an intricate puzzle of about 50 bones and in dolichocephalic dogs, these skull bones have elongated proportions. This is especially pronounced in the jawbones which gives these dogs their characteristic long and narrow muzzle.
There is no standard threshold for deciding a dolichocephaly, but they are generally categorised into a cephalic index below 75 which means the breadth of the head is less than three quarters of the length of its head.
Their long faces are physically better adapted to running and chasing and the position of their eyes makes it better suited to scanning for prey. Most of your sighthounds fall into this category and it makes total sense when you think about the position of their eyes.
Things to watch out for in dolichocephalic dogs:
Aspergillosis is a fungal infection which is caused by airborne spores which embed themselves in the lining of a dog’s nose. This can then potentially lead to rhinitis in dogs which is inflammation of the nasal lining, resulting in a runny nose, sneezing and nose bleeds. If left untreated, aspergillosis can damage the delicate bones of the nose or even spread into the lungs and other areas of the body. Long nosed dogs have more nasal lining than short nosed dogs so there is greater surface area for the Aspergillus spores to embed in but whether this is linked, or a coincidence is unknown.
Canine nasal cancer can affect any breed of dog, but some studies show that dolichocephalic dogs were 2.5 times more likely to develop nasal tumours than non-dolichocephalic breeds. They linked this due to them having a bigger surface area inside their nose which means more exposure to pollutants, irritants and allergens. Again, this may just be a coincidence.
This is a hole in the roof of the mouth which goes through to the nostrils and can be caused by infection, trauma, improper tooth extraction or congenital deformity. They are usually closed by surgery to prevent food or other foreign objects getting stuck and causing infection. Dolichocephaly dogs appear to have fistulas form more readily than brachycephalic dogs, but this again may be coincidental. No studies have been conducted to show how much fistulas occur in dolichocephalic dog breeds over brachycephalic dog breeds.
Are dolichocephalic dogs easier to train?
A professor did a study and found that mesocephalic dogs were regarded as the easiest to train and long and flat faces were both considered harder to train. A university then did a study about the links between dogs’ body shape and behaviour. They found that many undesirable behaviours such as separation anxiety, mounting people/dogs, compulsive staring, inappropriate urination/soiling, etc were less common in dolichocephalic breeds. However, they were more likely to chase things, bark persistently, steal food and be scared of strangers.
Dolichocephaly and their sense of smell:
A longer nose means more room for specialised scent reports inside the nasal cavity and consequently a more sensitive and refined sense of smell. A test was done to compare the scenting ability of short-nosed dog breeds with the scenting ability of long-nosed dog breeds. Dolichocephalic dogs outperformed the brachycephalic every time This was done without any preparatory training and the dogs were trying to find food. This was done as training could have interfered with the data analysis as the dogs would be trained to find food instead of determining whether long or short nosed breeds smell better.
Brachycephalic means short-headed in brachycephalic dogs, their skull bones have shortened proportions. Brachycephalic dogs include but aren’t limited to bulldogs, pugs, shih tzus, Pekingese, Boston Terriers, etc.
There are many different studies and theories out there about how brachycephalic dogs first came about due to their ancestors (wolves) not having flat faces. One study suggests that certain breeds such as English Bulldogs were selectively bred to develop flat faces to make them better at fighting as it was believed that shorter snouts created stronger jaws which would give these dogs an advantage in fighting and hunting.
Their popularity continues to grow but sadly we are aware of many health risks that trouble these dogs. We naturally want the absolute best love and care for our dogs. So here’s what to look out for and do speak to your vet if you have any concerns at all.
Things to watch out for in brachycephalic dogs:
Brachycephalic Obstructive Airway Syndrome:
This is a long-term breathing difficulty and an inability to cool down normally resulting in the impairment of a dog’s ability to exercise, play, eat and sleep. Abnormalities in the airways include narrowed nostrils and elongation of the soft palette which obstructs the passage of air though the nose and throat. In some breeds, this may be accompanied by the narrowing of the trachea restricting the airway and reducing space available for airflow. This makes it difficult to breathe freely and get enough air into the lungs. Due to the additional breathing efforts required, in some cases, it can lead to dogs suffering from a collapse of the larynx. There is an online resource from the Kennel Club on BOAS.
Signs of BOAS:
• Noisy breathing even at rest – may sound like snoring, snorting, or wheezing
• Struggling to breathing – excessive panting, heavy breathing
• Chest & stomach may heave when breathing
• May not be able to exercise normally – may rest on walks
• Might have blue or grey tinge to their gums – a signs of low blood oxygen
BOAS & Sleeping:
They may find it difficult to sleep normally and often snore while sleeping. They sometimes wake up due to brief periods where their breathing stops. They may try to prop their head up while they sleep to keep their airways open.
BOAS & Eating:
They may have problems with their gastrointestinal system which may consist of regurgitation, vomiting and coughing up foamy saliva. This often worsens overtime.
If your dog shows signs of BOAS:
You should seek veterinary advice immediately. Treatment options are available that aim to reduce the amount of obstruction to your dog’s airway and improve their breathing abilities. Early intervention if often recommended as this may prevent or slow further progression of symptoms.
To diagnose your dog, the vet will take a history of the dog’s clinical signs and will assess the degree of respiratory compromise in your dog. This may include a ‘walk test’ to see how they cope with a short amount of exercise and visual inspection of your dog’s nostrils. If your vet suspects your dog has BOAS, they may recommend that your dog’s airways are assessed under general anaesthetic where their nose and throat can be closely looked at. If abnormalities are seen e.g., their soft palate is overly long and/or thick and obstructing their away, their larynx is showing signs of collapse or their nostrils are significantly narrowed, your vet may recommend surgery.
BOAS Surgery & Post-Surgery:
Surgery may include opening up their nostrils, trimming away their excessive soft palate and removing collapsed parts of the larynx. Some specialists may offer advanced laser surgery to reduce further obstruction inside your dog’s nose (behind their nostrils). Surgery helps many dogs enjoy a better quality of life, but owners should be aware that dogs will not be ‘normal’ after surgery and precautions should still be taken to avoid exacerbating airway problems. This includes:
• Keeping your dog lean as obesity exacerbates breathing problems
• Avoid taking your dog out in hot weather
• Taking your dog on regular short walks to avoid putting stress on their airways while maintaining fitness
• Using a harness instead of a collar to avoid putting pressure on their airway
Elongated Soft Palate:
Almost every brachycephalic dog has an extra-long soft palate (tissue between the mouth and nose cavities) which covers the throat more than it should. Some dogs it only causes snoring and panting in hot weathers, but other dogs may need surgery to shorten the palate.
This is when the nostrils are either narrowed or collapse which makes it hard for dogs to breathe through their noses. This usually leads to a lot of mouth breathing and makes exercise difficult. Some puppies can grow out of this problem, but surgical procedures may be needed to open up the nostrils.
Everted Laryngeal Saccules:
Difficult breathing can inflame saccules (pouches) in the larynx and even flip them inside out which significantly obstructs the airway. In severe cases, oxygen therapy may be needed until surgery can be performed.
Shallows Eye Sockets:
Shallow eye sockets mean that many brachycephalic dogs cannot fully blink which results in areas of the cornea drying, especially in the centre.
Many brachycephalic dogs have imperfect eyelid anatomy as their eyelid opening is excessively wide. Their eyelids can sometimes turn in (entropion) or out (ectropion) which can lead to further drying of the cornea or damage due to the eyelashes.
In some dogs, the nasal folds come into contact with the cornea which causes direct damage due to rubbing of the skin or hairs with the surface of the eye. Corneal ulcers are very painful due to the number of nerve endings on the surface of the eye and, in some cases, may progress and lead to extensive scarring of the eye surface. This impairs vision and, in some cases, require the removal of the affected eye. Many can also lead to corneal pigmentation which is when there is a brown or black appearance over the surface of the eye. This is not thought to be painful, but pigmentation can impair vision.
Why are Brachycephalic Dogs At Risk of Spinal Problems?
Curved or screw tails result from abnormally shaped vertebrae in the tail region of the spine. These breeds have genes that tend to cause the formation of abnormally shaped vertebra in the spinal Colum as well as in the tail. Signs of spinal problems may include:
• Walking differently
• Weakness in the back legs
• Signs of muscle wastage in the back legs
• An abnormally shaped back
In some dogs, signs may progress over time and may lead to paralysis of the back legs and incontinence as a result. Other dogs may show no progression and may live relatively stable once they have stopped growing.
Diagnosis of Spinal Problems:
Your vet may recommend your dog has an x-ray to show any abnormalities in the shape of your dog’s vertebrae and spinal cord. However, an MRI scan is needed to further detect any areas of spinal cord compression.
Treatment of Spinal Problems:
In mild cases, no treatment is necessary other than monitoring dogs for signs of progression and making allowance for their gait abnormalities to avoid injury. In severely affected individuals, major surgery of the spine if required to attempt to stabilise the vertebrae and stop the spinal cord being compressed.
Surgery for Spinal Problems:
Spinal surgery is complicated and requires specialist treatment that isn’t always successful. Some dogs are completely paralysed in their hind legs which they may not recover the use of them after surgery. Long-term care of paralysed dogs may be considered by owners, including the use of mobility aids and incontinence management. Some owners may opt for euthanasia in severe cases where mobility cannot be restored.
Shortened and narrowed airways results in laboured breathing meaning that these dogs constantly struggle to cope with a lack of oxygen in the bloodstream. This puts a strain on the dog’s heart and makes them more susceptible to secondary heart problems.
Dog breeds have been selectively bred over many generations to meet certain characteristics and those bred to have a shortened upper jaw still have the same number of teeth as those with longer snouts (42 adult teeth). But because they have to fit these teeth into a much smaller area, their teeth can overlap which increased the risk of decay and gum disease.
Brachycephalic breeds can suffer from neurological problems because of their generally compressed skull shape. Syringomyelia is the most common of these which is a painful condition where cavities or cysts form in the spinal cord.
Mating & Giving Birth:
Very high number of brachycephalic breeds struggle to give birth naturally due to the size of the puppy’s heads. They commonly need Caesarean sections when the puppies are ready to be born due to selective breeding causing abnormally large heads and a small mother’s birth canal. Vets call this ‘dystocia due to foetal-pelvic disproportion’. Without assisted births, the mothers would likely die in pain during the birth and their offspring are unlikely to survive too.
Every breed that doesn’t fall into one of the above categories is left to fill the Mesocephalic category. These dogs don’t typically have any health watch due to their head shape. Although of course every breed has they own predispositions. If you’re interested in knowing more about the different breed watch information then you can check out breed watch from the Kennel Club.