Andrada Gilbert
Mrs. Hackelman
6/11/09
Revised Junior Research Paper
Archaeologists determined that breeding dogs happened at least 4000 years ago, and
perhaps as early as 10,000 years ago (Encarta, Breeding). Breeding means the development of
new types of plants or animals with improved characteristics. Breeding exists commonly among
dogs but has been used to enhance livestock. A dog breeder referrs to a person who intentionally
mates dogs to produce puppies. Breeders breed dogs to improve a dog’s genetics or make them
aesthetically pleasing. Most breeders’ focus on making the dogs look beautiful rather than the
genetics. Less experienced breeders do not bother to fully research the dog’s health and genetics.
Without careful research bad genetics like respiratory problems can be enhanced within certain
breeds and affect their lifestyles. Excessive inbreeding can limit the gene pool so that the breed
loses vigor. Limiting breeding causes bad genes to happen more often within that breed.
Breeding dogs can cause physical, medical, neurological and behavioral problems within the
dogs and result in expensive health care.
When someone breeds two of the same breed of dog then they are limiting the
diversification of genes. If each parent carries a defective gene then it is likely that the two
recessive genes may both be given to a puppy. When the two recessive genes combine they act
like a dominant gene thus affecting the puppy. See when one limits breeds to breeding with each
other they can make recessive genes dominant in that breed and cause physical and medical
problems to occur within the breed.
Skin problems, difficulty breathing, dislocating kneecaps, and hip dysplasia are just a few
of the many physical problems that arise. Sign problems develop due to breeding. For instance
the wrinkled skin of Chinese Shar-Peis triggers frequent skin infections. A skin allergy, atopic
dermatitis, inflicts itchy, inflamed skin on as many as 15 percent of all dogs, but certain breeds
are particularly susceptible (Dogs That Changed The World). Excess wrinkles on the face can
create lesions or even blindness because the skin rubs the eyes.
More than sixty purebred dogs suffer from inherited forms of cataracts, while progressive
retinal atrophy, a common cause of blindness in purebreds, is particularly a problem in Old
English Sheepdogs and Papillons. Long neck and large head of breeds can cause the compression
of the spinal cord in neck vertebrae, leading to wobbling and falling. The huge head of the
Bulldog necessitates the need for human interaction to give birth. Selective breeding of the
disproportionately short legs of breeds has led to bowed legs and chronic problems with elbow
dislocation.
Numerous physical characteristics affect the conditions of certain breeds. For example,
flat-faced dogs like pugs have difficulty breathing due to shortened air passages. Gingivitis,
plaque, and tartar afflict small breeds. Malocclusion, a jaw problem, often is inherited in petite
dogs (Rice 50). Short nosed breeds usually develop a cleft palate. A cleft palate is defined as
genetic disease that is manifested by partial or total lack of fusion of the two bones that form the
palate (51).
Besides jaw diseases that can occur in tiny dogs, intervertebral disc disease can exist. It
may be able to occur anywhere along the spine. The calcified disc protrudes on the space already
occupied by spinal nerves. Swelling and pain results to the pressure on the nerves. Partial
paralysis of the hind legs may result from pressure on the motor nerves (53).
Dislocating kneecaps are more common amongst small dogs. Medial patellar luxation is
when the patella slips out and goes to the inside of the leg. This type of luxation is common in
toy breeds and miniature breeds. 25% of cases are seen in both legs (Patellar Luxation). The
dislocation of the kneecap can cause lameness of the leg. Small breeds are more at risk for
medial patellar luxation but it does not mean the large breeds cannot inherit the disease.
Large dogs are prone to hip dysplasia and malignant bone tumors. Canine Hip Dysplasia
is a condition that begins in immature dogs with instability or a loose fit of the hip joint (Canine
Hip Dysplasia). It stretches the fibrous joint capsule and produces pain and lameness. Most
dysplastic dogs are born with normal hips but due to genetic and possibly other factors, the soft
tissues that surround the joint start to develop abnormally as the puppy grows (Hip Dysplasia in
Dogs: Diagnosis, Treatment, and Prevention). If a parent has hip dysplasia, then the offspring are
at greater risk for developing hip dysplasia. Causes of hip dysplasia are considered to be
multifactorial; including both hereditary and environmental factors (Canine Hip Dysplasia).
Young dogs obtain osteochondrosis, in which normal cartilage development fails. It
occurs commonly in the elbow joints of large dogs. Symptoms are usually exhibited between
four to eight months of age. Lameness and stiffness of the leg exhibit signs of the disease. Both
elbows maybe affected, even though only one shows the signs.
Over 300 genetic health problems occur in dogs. The risk of health problems occurring in
a purebred dog is higher than in a crossbreed or mixed breed (The Truth About Purebred Dogs).
Medical problems occur while breeding dogs like immune system disease, and blood disorders.
Immune system disease stems from breeding. Dogs that have been bred by a breeder who does
not use suitable research methods to decide if two dogs are ideal to breed collectively, often
obtain an immune system disease. A number of inherited diseases compromising the immune
system have been noted in dogs, including primary severe combined immunodeficiency among
Basset hounds, Cardigan Welsh Corgis, and Dachshunds (Dogs That Changed The World).
Immune system disease commonly affects dogs because breeders did not carefully research the
dogs’ health problems. If a dog has a frail immune system then the capability of fighting off
diseases decrease. This puts the dog in danger of not being able to abolish viruses that a dog
devoid of immune disease can without difficulty obliterate. Also the effects of a disease take a
harder toll on the dog if the immune system is damaged. The resistance of the immune system to
diseases is a vital part of the body. It protects the organs from being damaged and keeps the dog
healthy. If breeding takes place then the dog’s health is placed jeopardy. Lacking the appropriate
study of the breeds being combined can impinge on the puppies’ health. Diseases will easily
creep up on the puppy if the immune system is feeble.
Dogs also inherit blood disorders. A disturbance to the functioning of blood for example
a decrease in blood clotting defines a blood disorder. An inherited abnormality that affects the
ability of the platelets in the blood to clump together after an injury takes place among Bassett
Hounds. Without the capacity of the platelets clumping together, loss of blood will come about.
Clotting problems also plague dogs with von Willebrand’s disease.
Von Willebrand’s disease exits as an inherited bleeding disorder. It affects the blood’s
ability to clot (What Is von Willebrand’s Disease?). Accurate blood clotting is needed so
infections will not ensue. Blood clotting prevents a huge amount of blood to pour out of a tiny
cut. Blood clotting regulates the blood flow in the body because more blood flows to the wound,
which provides less blood to flow to significant organs throughout the body. With breeding dogs
the knack of blood clotting reduces. Breeding dogs puts the puppy at risk of excessive bleeding
from a wound because the blood is not able to clot.
Other organs and systems can be defected by genetics. Gastric torsion, or bloat, a
potentially life-threatening inability to expel gas from the digestive system, is common among
deep-chested breeds. Kidney disease is inherited from English Cocker Spaniels and Dalmatians
are prone to kidney stones. Bedlington Terriers inherit a condition, which high levels of copper
accumulate in their liver.
High blood pressure afflicts many small breeds. There have been instances where
breeding dogs with hypertension, or high blood pressure, have produced offspring with
hypertension (High Blood Pressure in Dogs). One study found that between 0.5 percent and 10
percent of dogs suffer from high blood pressure.
Genetics strongly influence Cancers. Bone cancer takes place more frequently among
large dogs because their bones are stressed by carrying so much weight. Golden Retrievers likely
arise to leukemia and brain tumors. High rates of malignant blood vessel tumors are also
prevalent in Golden Retrievers. Scottish terriers are more likely to develop bladder cancer than
other breeds. German Shepherd Dogs and Chow Chows are predisposed to gastric cancer.
Many pure breeds are inconvenienced with neurological and behavioral problems. Bull
terriers often compulsively chase their tails, and pugs are predisposed to Pug Dog encephalitis.
Pug Dog encephalitis only exists in pugs and displays a fatal brain disease that causes seizures.
Selective breeding and inbreeding may play a large role in the disorder’s occurrence among
companion animals (JAVMA Study Blames Selective Breeding and Inbreeding for OCD).
Obsessive-compulsive disorder in dogs expresses itself through repetitive behaviors that
include circling, tail chasing, fence running, pacing or spinning, fabric chewing, and pica. Breed
origins seemed to lead to associated behaviors. Dobermans, German Shepherds, and English Bull
Terriers are predisposed to obsessive-compulsive disorder. Dobermans tend to suck on their skin
while German Shepherds chase their tails. English Bull Terriers tend to stick their heads under
things and freeze in that position. It is also known that herding dogs tend to chase their tails,
which led researchers to believe that OCD was based on genetic factors.
The intelligence of a dog may decrease because of breeding. Scientists in Sweden have
found strong evidence that breeding for appearance has led to a decline in intelligence (Pedigree
Dogs are Becoming Stupid as we Breed Them for Looks, Not Brains). "Modern breeding
practices are affecting the behaviour and mental abilities of pedigree breeds as well as their
physical features” reported Kenth Svartberg, an ethologist from Stockholm University. Since
breeders are concentrating on the looks of the dogs the skill level is not considered. Dogs that are
breed today respond less to comands and do not seem as alert. Owners look to by docile, petite
dogs like chihuahuas rather than the large strong dogs. The need for a dog’s skill level of herding
or gaurding decreased dramaticly and the instinct is slowly fading.
Selective breeding can change various types of behavior. Each breed is sought out to
perform different tasks. Every time a breed is bred the characteristics of its instincts are bred
with it. For instance herding dogs are genetically constructed to instinctively herd sheep. Herding
dogs act hyper due to the excessive activity the breed is used to. Greyhounds are considered sight
hounds and are bred for their fast speeds. People use them for hunting and they demonstrate
hunting skills. Even if owners do not use them for hunting one will notice their instinct to chase
squirrels.
Not only is the level of activity hereditary but the amount of barking is also passed down.
Cocker Spaniels bark infamously unlike Basenjis. Beagles also tend to bark often. Socializing is
also passed down genetically and also depends on the way the breeder raises the puppies. Some
breeds tend to be more outspoken than others. Pit bulls have been breed for dog fights because
the level of aggression is prominent. Although if a person raises a pit bull in a calm environment
it will not show aggression. Greyhounds appear calm and relaxed. Most greyhounds get along
with other dogs well and tend to be quite. On the other hand small dogs carry a lot more energy
and are often hyper. The attitudes of certain breeds are prevalent amid the breed.
Inexperienced breeders tend to breed dogs for their looks. These “backyard breeders” do
not research both dogs’ physical and medical attributes to find out if the puppies will turn out
healthy. Breeding the same breeds can enhance bad genetic traits. That is why “mutts” are
considered healthier than purebreds. If breeders research traits of dogs then they may be able to
breed together two breeds that can balance each other’s bad qualities. However many people just
breed for looks which can harm the puppies throughout their growth. The breeding for looks can
even affect the intelligence of the dog. Certain breeds may be prone to physical, medical or
behavioral anguish. The passing down of corrupt genes can sometimes be prevented with the
proper research.
When breeding the price can add up quickly. More money is lost than gained from
breeding. First it costs money to for a stud, purebred male, then the expense of food goes through
the roof. A pregnant female may need up to four times as much food than what she normally eats
(Johnson, Costs). Whelping box, heat pads, heat lamps, thermometer, scissors, towels, baby
scales, tweezers, hemostats, baby suction bulbs are a necessities when raising puppies. Those
expenses still does not even account for the high vet bills. Also time needed from work cuts into
your budget and reduces the amount of money one makes to pay for all the equipment necessary
to breed dogs. More money will be spent if the puppies get sick or if the mother has birthing
complications. Money will be spent on getting a professionals advice about raising a liter of
puppies and taking care of pregnant mothers. Training the puppies will also spend a lot of money
and take up free time. If someone really thinks about breeding than they will conclude that they
end up losing more money than they gain. Even if one sells the pups for a couple hundred bucks
it still will not make up for all the money used to breed the dogs.
Breeding affects physical, medical, neurological and behavioral systems in dogs. The cost
of breeding is expensive. Breeders intend to create a beautiful looking dog or improve its
genetics. Inbreeding can cause defective genes to exist commonly among breeds. Reducing
breeds to mate with it’s own breed causes defective genes to arise. Improving characteristics
among animals especially dogs describes breeding. Breeding dogs became common but years
ago farm animals have been bred to enhance milk or eggs. Millions of people breed dogs without
using proper research. The breeding of dogs continued since thousands of years.