COMMON PROBLEMS IN PEDIGREE DOGS: HEALTH CHALLENGES
Compiled & shared by-Dr. Santosh Giri
The dog (canis lupis familiaris) is one species which over the world has over 1000 different breeds. Dog breeds developed over hundreds, maybe thousands of years, to fulfil specific functions, such as the ability to run fast, hunt for prey, pick up birds, pull sledges, guard property, search and rescue, etc. Aside from this dogs are the natural companion for humans, and a close relationship between our two species has developed over millennia.
Towards the end of the 19th century a new hobby began to emerge: dog showing. People with leisure time to spare gathered socially and paraded their pet dogs in a competition to find the most beautiful dog. Later, this developed into competitions to find the best specimen of a particular breed. The first Crufts dog show took place in 1891 and the idea of a ‘purebred dog’ began to take hold. Purebred dogs were regarded as somehow better than mixed breed dogs, which were (and still are) referred to as ‘mongrels’. The Kennel Club was founded to run dog shows and make the rules for breeding and showing. It also registers all pedigree dogs and issues pedigree certificates so that a dog’s ancestry can be traced.
In order to maintain ‘purity’ each breed had a written description of its size and appearance, called a breed standard. Once a breed had been established the stud books were closed.
This means that in order to breed a purebred dog you must only breed within this closed gene pool. Further selection took place due to the competitive nature of dog showing – everyone trying to breed from dogs which had a Champion (or many) in its pedigree. Certain dogs which were greatly admired were, and still are, over used – the so called ‘popular sire syndrome.’ In this way a breed’s gene pool becomes narrower and narrower, and if a popular dog happens to carry faulty or disease causing genes (gene mutations) this will be spread far and wide throughout the breed population. Genes are inherited in pairs, one each from the dam (mother) and sire (father).
For many diseases a dog would need to inherit a deleterious (harmful) gene from both its dam and sire. The narrower the gene pool in a dog breed the more likely this is to happen.
Generally speaking, a healthy species is one that has a great deal of genetic diversity, like humans. Genetic diseases do occur in humans but they are rare, whereas in dog breeds a genetic disease can affect a large proportion of the population.
So, are pedigree dogs a bad thing?
No, not necessarily, and most dog owners will have preferences about the type of dog they have as a pet. Obviously the dog would need to fit in with their circumstances and lifestyle.
There are ways that you can retain most of the dog breeds, if care is taken by breeders and breed clubs to have a proper breeding strategy. The aim of this would be to maintain as much genetic diversity as possible within the breed.
Here are some suggestions:
- Using as many males as females in a breeding population. Avoid the ‘popular sire’ effect.
- Avoiding incestuous matings. No matings closer than cousins should ever take place.
- Keeping the coefficient of inbreeding (COI) as low as possible over 8 to 10 generations
- Using the Kennel Clubs Mate Select programme to find out the COI of any proposed mating. Check this with the breed’s average COI and only breed when the COI result will be lower than the breed average.
- Analysing parental pedigrees before any mating and avoiding matings where the same name appears on both sides of the pedigree.
- Using assortative mating (mating unrelated parents who are similar for the desired traits) instead of inbreeding/line breeding.
- Keeping generation time as high as possible. This is because genetic losses occur with each generation so the larger the gap between generations the better (ie, four years between generations is better than two)
- Avoiding repeat breeding (the same two dogs more than once or twice)
- Using at least two of a litter for future breeding rather than just one (the ‘best’ one).
- Out crossing within a breed rather than using dogs from one kennel. Ideally this should include dogs from overseas populations.
- Breeding for balanced traits (health, vitality, temperament, working ability, intelligence, structure, and type) rather than focussing of one or two traits.
- Occasionally breeding to a related breed (for example, Cavalier King Charles Spaniels to say a Cocker Spaniel). No-one would know the difference in a couple of generations.
If proper care was taken with our dog breeds along these lines the risk of genetic diseases would be much lower.
Needless to say, any dog breed which encourages unhealthy physical traits should be bred back to a less exaggerated type. If necessary the breed standard should be re-written to prevent interpretations by breeders and show judges that are harmful to the dog.
5 COMMON PROBLEMS IN PEDIGREE DOGS
(breathing, birthing, walking, eyes, skin)
- DIFFICULTY BREATHING
Some breeds of pedigree dogs with very short muzzles (termed brachycephalic) can have difficulty
breathing due to a disorder known as brachycephalic airway obstruction syndrome (BAOS). In these dogs the skull length is reduced, but the amount of soft tissue in the muzzle is not, resulting in the same amount of tissue being squeezed into a smaller area. This characteristic has been deliberately selected in order to conform to the breed standard.
Dogs with BAOS usually have small and narrow nostril openings and elongated soft palates that hang down into the airway, both of which make breathing difficult. BAOS may be progressive with laryngeal and tracheal collapse occurring at later stages. Some dogs require surgery to alleviate their breathing difficulties and to try to improve their quality of life.
Symptoms
- Serious difficulty breathing
- High blood pressure
- Low oxygen concentration in the blood
- Fainting or collapsing due to a lack of oxygen
- Facial fold dermatitis (inflammation/infection of the skin due to excessive skin folds on the face)
- Excessive flatulence (as affected dogs habitually gulp and swallow air to try to overcome their breathing difficulties)
Breeds at risk
- Pekingese, English Bull dog, Cavalier King Charles Spaniel, French Bull dog, Pug, Staffordshire
Bull terrier, Shih Tzu, Lhasa Apso, Shar Pei, Boxer and Boston Terrier, among others.
- DIFFICULTY GIVING BIRTH
Certain pedigree breeds frequently have difficulty giving birth without surgical intervention (termed obstructive dystocia). Individuals of these breeds are deliberately selected for a large head, broad shoulders and narrow pelvis simultaneously, which results in a large foetal head:maternal pelvis ratio. This is known as cephalopelvic disproportion and means that the pup’s head and shoulders are too large to fit through the mother’s pelvic canal. Bitches with this problem cannot give birth safely without veterinary assistance in the form of a Caesarean section.
Breeds at risk
- This problem is common in breeds with large heads and wide shoulders such as English
Bulldogs, Pugs, Boston Terriers and Scottish Terriers.
- DIFFICULTY WALKING
Certain pedigree breeds have been selectively bred for physical features that can lead to walking
difficulties.
Chondrodystrophia is a condition in which the cartilage grows and matures abnormally and the long bones fuse faster than normal, leading to stunted growth. Chondrodystrophic breeds are actively selected for this abnormality, which results in disproportionately short and curved limbs. These breeds have an increased likelihood of spinal injury, not only due to their excessively long spinal columns andexcessively short legs but also because their abnormal cartilage makes them susceptible to ruptured discs (termed Intervertebral disc disease). When the spinal disc ruptures it puts direct pressure on the spinal cord, causing extreme pain and potential neurological problems.
Symptoms
- Severe pain
- Neurological deficits – disruption of normal nerve signals leading to movement problems,
including difficulty walking and in severe cases, complete paralysis
Breeds at risk
- Basset Hound, Dachshund (long, smooth and wire-haired), Miniature Dachshund (long, smooth
and wire-haired), Shih Tzu and Lucas terriers, among others. Basset Hounds also have a
relatively large and heavy head, which places further strain on their spinal column.
Hip dysplasia is the abnormal formation of the hip joint and is probably the most commonly
recognised musculoskeletal problem in dogs.
Symptoms
- Lameness
- Progressive degeneration of the hip joint
- Crippling arthritis
- Pain, difficulty walking
Breeds at risk
- German Shepherd, St Bernard, Alaskan Malamute, Bulldogs, Golden Retriever, Rottweiler and
Labrador Retriever, among other breeds and particularly large breed dogs.
Elbow dysplasia is the abnormal formation of the elbow joint.
Symptoms
- Lameness
- Progressive degeneration of the elbow joint
- Crippling arthritis
- Pain, difficulty walking
Breeds at risk
- Bernese Mountain dog, Rottweiler, Labrador Retriever, Golden Retriever, Bull Mastiff,
German Shepherd and St Bernard, among other breeds and particularly large breed dogs.
- SERIOUS EYE PROBLEMS
Pedigree dogs are predisposed to a number of serious eye diseases, many of which are the result of selectively breeding for a particular physical type in order to conform to the breed standard. Three common problems are corneal trauma and ulceration, entropion and progressive retinal atrophy.
Corneal trauma and ulceration is an erosion of the outer surface of the eye following injury. Breeds with very short muzzles (brachycephalic) have a high susceptibility for corneal trauma and ulceration. This is because the shorter the nose, the shallower the eye socket, and thus the more prominent the eye. Prominent, bulging eyes are at greater risk of injury and sometimes the eyes can proptose (pop out of the eye socket). In these breeds the eyelids cannot close properly over the bulging eye leading to dry eye and potential ulceration.
Symptoms
- Pain & discomfort• Potential blindness
- Sometimes the affected eye needs to be removed
Breeds at risk
- All brachycephalic breeds are at risk including the Pug, Shih Tzu and Pekingese
Entropion is a condition where the eyelids fold inwards and rub onto the surface of the eye. This
condition occurs frequently in those breeds that have been selected for wrinkled facial features
(excessive skin fold about the eyes). These folds also predispose the dog to facial fold dermatitis.
Symptoms
- Constant rubbing/irritation from the hairs, leading to trauma and ulceration of the eye
surface
- Pain & discomfort
- Potential blindness
Breeds at risk
- Shar Pei, Chow Chow, British Bulldog, Pekingese, Pug, Shih Tzu, Pomeranian and Cocker
Spaniel, among many others. Shar Pei pups often require an ‘eyelift’ surgery in infancy to
prevent erosion and ulceration of their eyes. This surgery may need to be repeated at later
stages.
Progressive retinal atrophy (PRA) is the term given to a group of genetic eye diseases that cause the retina to gradually degenerate. The result is progressive loss of vision and eventual blindness. In nearly all breeds the condition is inherited as an autosomal recessive trait, thus breeding from close relatives greatly increases the risk of inheriting this disease.
Symptoms
- Progressive loss of vision
- Eventual blindness
Breeds at risk
- Many breeds of dogs including those in the Gundog, Hound, Non-Sporting, Terrier, Toy,
Utility and Working dog groups, but most commonly Cocker Spaniels, Poodles, Australian
Cattle Dogs, Silky Terriers and Labradors.
- SERIOUS SKIN PROBLEMS
Many pedigree breeds are predisposed toward the development of serious skin problems, many of
which are the result of selectively breeding for a particular physical type in accordance with the breed standard requirements. Two examples of serious skin problems are: excessive skin folds and inherited allergies.
Excessive skin folds: many breed standards require that the dog have excessive and wrinkled skin. Unfortunately this excess skin leads to folding and subsequent inflammation and infection.
Symptoms
- Dermatitis (inflammation/infection of the skin)
- Discomfort & irritation
- Pain
Breeds at risk
- Facial fold dermatitis: brachycephalic breeds such as the English Bulldog, Pug, Pekingese,
Boston Terrier and French Bulldog (excessive facial folds may also lead to entropion & corneal
ulceration).
- Tail fold dermatitis: English Bulldog, Pug
- Lip fold dermatitis: American Cocker Spaniel, English Cocker Spaniel, St Bernard.
- Leg fold dermatitis: Basset Hound
- Labial fold dermatitis: Spaniels, Setters, Golden Retriever, St Bernard, Blood Hounds and
Newfoundlands
- General body fold dermatitis/interdigital dermatitis: Shar Pei
Inherited allergies: certain pedigree dog breeds are predisposed to major skin allergies that can
severely compromise quality of life.
Symptoms
- Constant and severe itching that often interferes with sleeping and the ability to have a
normal life
- Lesions may become infected causing discomfort and pain
- Dogs with skin allergies often have accompanying ear infections (also with an allergic basis)
that can become chronic and difficult to treat
Breeds at risk
- West Highland White Terrier, Shar Pei, German Shepherd, Bull Terrier, Pug, English Springer
Spaniel, American Cocker Spaniel and Dalmatian among many others.
- Dogs that are selectively bred for extra-long ears that hang over their ear openings (e.g.
American Cocker Spaniel, English Springer Spaniel, Basset Hound, Poodle etc) are also
predisposed to ear infections as the covered ear canals can become abnormally hot and
humid (perfect breeding grounds for bacterial and yeast infections). The Shar Pei is also
prone to ear infections due to their excessively narrow ear canals, with some requiring ear
surgery to open the canal.
SPECIFIC BREED-ASSOCIATED DISEASES
Some diseases can be specific to one pedigree breed only. Two examples include:
Familial Shar Pei fever (FSF) is a recessively inherited genetic disease in the Shar Pei. Breeding from close relatives greatly increases the risk of inheriting this disease.
Symptoms
- Fever
- Anorexia
- Severe joint swelling
- Severe pain
- Dogs may not be able to walk at all during severe episodes
English Springer Spaniel fucosidosis is an enzyme deficiency/storage disease with most cases
reported occurring in the English Springer Spaniel. This is a recessively inherited disease thus breeding from close relatives greatly increases the risk of inheriting this problem.
Symptoms
- Neurological problems – lack of coordination, tremors, weakness, difficulty eating, difficulty
walking, partial blindness, deafness and anxiety
- This is a progressive disease with no treatment currently available
OTHER COMMON INHERITED DISEASES
Heart disorders
Certain pedigree breeds are predisposed toward heart disorders such as heart valve defects in the
Cavalier King Charles Spaniel and other types of inherited heart disease in the Boxer, Rottweiler,
Doberman, Great Dane, Golden Retriever, Newfoundland and Irish Wolfhound, among others.
Gastrointestinal disease
Certain pedigree breeds are predisposed toward gastrointestinal diseases such as Gastric dilation and volvulus (GDV), particularly large, deep-chested breeds. Breeds at risk include the Irish Setter, Great Dane, German Shepherd, Akita, Weimaraner, Boxer and Basset Hound, among others. GDV is a very painful and potentially fatal medical emergency.
Chest and abdomen conformation are thought to play a major role in GDV. It appears that the chest depth/width ratio is highly correlated with the risk of GDV. Breeds with deep and narrow chests are more likely to develop GDV. Unfortunately, certain breed standards still require that the dog have a very deep and narrow chest. This needs to be rectified by the relevant authorities as soon as possible.
Blood disorders
Certain pedigree breeds are predisposed toward blood disorders such as clotting abnormalities e.g. Von Willebrand’s disease and haemophilia, among other conditions.
Kidney disorders
Certain pedigree breeds are predisposed toward kidney problems. Two categories include:
o Recessively inherited kidney diseases (thus breeding from close relatives greatly increases
the risk of inheriting these diseases). Breeds at risk include the English Cocker Spaniel,
Britany Spaniel, Cairn Terrier and West Highland White Terrier, among others.
o Dominantly inherited kidney diseases. Breeds at risk include the Bull Terrier, Dalmatian
and German Shepherd, among others.
Neurological disorders
Certain pedigree breeds are predisposed toward neurological diseases such as syringomyelia. Breeds at risk include the Cavalier King Charles Spaniel, Griffon Bruxellois and Pomeranian, among others.
Hormonal disease
Certain pedigree breeds are predisposed toward hormonal disorders for e.g. thyroid hormone disease.
Immune system disorders
Certain pedigree breeds are predisposed toward immune-system disorders such as immune-mediated anaemia, among other conditions.
INADVERTENT CO-SELECTION OF LINKED GENES
As a result of selective breeding there is sometimes co-selection of a harmful gene linked to the one that is under selection.
White coat – deafness: inherited deafness is a common condition in dogs, especially breeds with a white coat colour and poor pigmentation of the iris and retina. Inherited deafness is thought to be a recessive trait.
Breeds at risk
- Dalmatian, English Setter, English Cocker Spaniel, Bull Terrier, Australian Cattle dog,
Whippet, Catahoula Leopard dog, Jack Russell Terrier, Australian shepherds and Border
Collies, among other breeds
Dalmatian spots: in the Dalmatian it appears that selection for the characteristic black spotting
pattern may have inadvertently selected for a linked gene that causes abnormally high urate excretion. High urate excretion is a recessive trait in Dalmatians and has led to a high incidence of urate bladder stone formation in this breed. Bladder stones can cause pain and discomfort and may be life threatening if they cause a urinary blockage. Dalmatians are also predisposed toward skin problems, which are also thought to be associated with their abnormally high urate excretion. These problems are now thought to potentially affect all purebred Dalmatian dogs.
A recent study found that out-crossing Dalmatians to Pointers and then backcrossing to Dalmatians
seems to have been successful in ridding the offspring of this problem however, problems with
registering the subsequent offspring have provided little incentive for breeders to utilise such sound breeding practices.
Cocker Spaniel coat colour: when comparing different coloured Cocker Spaniels, studies found that “dominant-aggressive’ behaviour varied greatly between different coloured dogs. Breeders who choose specific colour types to breed may inadvertently select for an aggressive temperament.
Double dapple coated Dachshunds: there is a link between Dachshunds with a double dappled coat and blindness and deafness.
The Pros and Cons of Pedigree
People give their dogs all sorts of names, finding creative inspiration from many sources. Some name their dogs after movie or book characters, sports teams, or favorite relatives! Scout, Buddy, Rambo, Ariel, Dodger, Duke….There are more dog names than there are dog breeds.
Regardless of their endowed name, the official Latin name for the domestic dog is Canis lupis familiaris. Within this scientific classification, the canine species includes over 1,000 different breeds, each with a unique name and pedigree. Plus there are infinite combinations of breeds that make up the lovable family of dogs affectionately dubbed ‘mutts’.
When choosing a dog, potential pet owners often consider acquiring a pup with a pedigree vs. a mixed breed. In order to make a more educated choice, it’s good to know a little about what makes a pure breed so ‘pure’ as well as what ‘mutts’ have to offer.
What is a purebred?
The creation of a pure canine bloodline is historically a complex accomplishment. Specific dog breeds were originally developed and refined over many generations to develop traits that made them suitable for certain jobs. Mating two dogs with specific traits was arranged to produce pups that could accomplish certain tasks; e.g., run fast, pull sleds, guard property, or retrieve birds. The best pups of the litter were identified and selected for future breeding. After several generations of critical selection, pups with specific traits were consistently produced and a new “breed” was identified – Greyhounds for speed, Huskies for sledding, German Shepherds for protection, Labradors for retrieving birds, etc.
“After several generations of critical selection,
pups with specific traits are consistently
produced and a new ‘breed’ is identified.”
Around the end of the 19th century, selective breeding gained popularity for a totally different reason. The affluent population of pet owners gathered at social functions and enjoyed parading their dogs around, comparing them to other dogs. From this pastime a new sport, showing dogs, emerged. To ensure fair competition in the show ring, written breed standards were adopted that described each specific breed’s appearance and temperament and reflected the breed’s original function. At dog shows, the best specimen of a particular breed was deemed the winner.
The goal of breeding and selecting dogs with certain physical features, whether for work or show, is to produce the ‘ideal’ dog. A consequence of this process may be inbreeding, which results in some less desired genetic traits becoming more common along with the traits people are trying for. If there is a recessive gene for an inherited disease, such as hip dysplasia, a pup born of related dogs has an increased chance of having that particular problem.
Natural mating of related dogs is not the only way inherited defects permeate a breed. Sometimes, a male dog that fits the breed standard and wins numerous championships will be used to father many litters (naturally or through artificial insemination) from totally unrelated mothers, and his genes, both good and bad, become widely spread through the breed. Even though the mother and father are not related, there is a good chance that future generations will be linked through the father.
How are safe breeding practices enusred?
Dogs of pedigree can be wonderful pets or service dogs, so avoiding inherited medical problems is important. To safeguard the integrity and health of a bloodline, guidelines have been developed.
- Review pedigrees prior to mating to ensure that you are not breeding close relatives. Most pedigrees outline ancestors for several generations.
- Use several breeding males and females to add diversity to the population.
- Avoid mating siblings to siblings, and parents to offspring. Mating of distant cousins is okay.
- Do not breed dogs with known genetic defects. It is best to have these dogs spayed or neutered.
How do breed standards help?
Breed standards help educate potential pet owners about what to expect when choosing a specific dog breed. People can research breed standards for information about the size, temperament, and potential health problems of their chosen pup. Future dog owners can anticipate how big the pup will be, what he will look like, and what medical problems to watch for.
For example:
- Bulldogs are particularly prone to respiratory problems associated with short nose and elongated soft palate.
- Pugs tend to experience ocular problems associated with bulging eyes (corneal ulcers, prolapsed eyeball).
- Beagles often have epileptic seizures.
- Shih Tzus, Toy Poodles, and Yorkshire Terriers may have luxating patellas (knee caps) that cause intermittent lameness.
It is important to understand that any dog of any breed can have these health issues but certain breeds are more predisposed than others. Mixed breed dogs, while not exempt from these medical problems, are less likely to develop them due to ‘hybrid vigor’ – a variety of genetic material gives mutts a health advantage over their upper crust canine companions.
What are some of the pros and cons of pedigree?
There are pros and cons to choosing a purebred dog over a Heinz 57 pup.
Pros: You will have a good idea what your pup will be like when he grows up. A mixed breed pup cannot be as easily pegged.
Cons: Your dog may have a health or behavioral issue related to his carefully scripted blood line that may show up immediately or become evident later in life.
Do a little research before selecting a new pup, purebred or otherwise, and remember this: whatever you name your dog, you will call him ‘yours’ no matter what he looks like!
Reference-On Request
