By Anirudh NarendraNath
Out of the many animals mankind has been domesticating and rearing, few have seen as much change as the dog. ‘Man’s Best Friend’ has experienced many changes over thousands of years of domestication. Lithe and fierce at one point, dogs have diversified to fit the needs of mankind as necessary. Today, we have shaggy behemoths, pocket-sized chihuahuas, flat-faced bulldogs, low-lying sausage dogs and many, many more dog types all around the world. However, this diversification may end up causing dogs harm.
Selective breeding is the process used to bring about such changes. This can be seen in other animals, for example sheep - a sheep that has softer wool will be bred with another that needs less food until they eventually have offspring that carries both of these traits. An important thing to note is that these changes are not always the best for the animal’s own survival - it is to benefit humans. This can be observed in dogs - dogs with personalities and physiologies better suited for a task are bred so that their offspring will also receive these traits.
Pure breeding is a method of ensuring that the exaggerated physical traits seen in dogs today are passed on. Pure breeding is essentially when an animal’s parents and ancestors are all from the same species. This has its benefits, especially when concerning the role of dogs as companion animals - purebred dogs have more predictable physical traits and behaviors, which can allow a potential owner to see what dog would best suit them and plan for food, space and grooming accordingly (Kelly Sundstrom, 19th May 2021).
The downside, however, is that pure breeding tends to lead to an increased vulnerability to genetic diseases in some populations of purebred dogs, as compared to those of mixed breed dogs. What are some of the genetic diseases that dogs are often afflicted with?
Today’s large dog breeds, such as German Shepherds and Saint Bernards, are often victims of hip dysplasia, where the increasing muscle mass outpaces the growth of the skeleton. This growth imbalance changes the weight distribution around the hip joint, altering the formation of bones. Severe arthritis is also contracted as the condition worsens. In Saint Bernards dogs, the chance of developing hip dysplasia is a staggering 50% (Mindy A. Cohan, 4th December 2016).
Bulldogs, pugs and terriers are breeds known for their flat faces and rounded heads, which many find endearing. Their skull shape, as a result of compression and genetic breeding, has led to abnormalities in their respiratory system. Slit-like nostrils and deformed tracheas are some of the defects that can be observed that greatly impede the breathing of these dogs. Stress can even cause this afflicted trachea to close up as a result of panicked breathing and panting. This condition is known as brachycephalic syndrome (Mindy A. Cohan, 4th December 2016).
Chondrodysplasia is a condition that commonly affects Dachshunds and Basset Hounds - their short legs and lengthy bodies cause joint pain and arthritis, and even greatly strain the intervertebral discs as the body length does not correspond to the leg length. Extreme cases of this can cause paralysis (Chewy Editorial, 20th January 2021).
Speaking of paralysis, another disease is degenerative myelopathy, where degeneration of nerves in the spinal cord causes the dog’s hind limbs to become weak. As one might expect, basic movement-related tasks become a struggle - getting up, sitting down, jumping, climbing at an angle and more.
A common name when discussing diseases in dogs is the Cavalier King Charles Spaniel, which is said to have been popular in royal courts in Asia and Europe. Genetic bottlenecks led to a small percentage of dogs being able to pass along their genes, harmful ones included. These dogs have the potential to develop cataracts, kidney stones, hip dysplasia, dental diseases, ear infections, dry eye, and mitral valve disease - where malfunctioning valves lead to blood from the left ventricle leaking into the left atrium (Public Library of Science, 2nd September 2021).
These are just some of the diseases that afflict dogs. The owner’s care of the dog is obviously a factor, and can in fact keep these diseases at bay; but some of these cannot be fixed as easily as regular grooming. It is important to note that not all purebred dogs are inherently more predisposed to diseases than mixed breed dogs, but certain populations of purebreds are more vulnerable.
A longer body or a more scrunched-up face shouldn’t have to be a leading factor when getting a dog - these companions deserve the best, yet breeding practices have led to them contracting harmful and painful illnesses. A mixed breed dog that doesn’t appear as glamorous, comical or fluffy will provide just as much love as any other dog, at lesser risk to its own health.
BIBLIOGRAPHY
1. “Cavalier King Charles Spaniel Health Problems.” AFI, www.animalfriends.co.uk/dog/dog-advice/dog-breed-health-problems/cavalier-king-charles-spaniel-health-problems/.
2. Cohan, Mindy A. “The 6 Most Common Genetic Disorders in Dogs.” PetMD, 4 Dec. 2016, www.petmd.com/dog/slideshows/6-most-common-genetic-disorders-dogs.
3. Editorial, Chewy. “5 Common Congenital Dog Diseases.” BeChewy, Chewy, 21 Jan. 2021, be.chewy.com/5-common-genetic-diseases-of-dogs/.
4. Staff, Science X. “Cavalier King Charles Spaniels Carry More Harmful Genetic Variants than Other Breeds.” Phys.org, Phys.org, 2 Sept. 2021, phys.org/news/2021-09-cavalier-king-charles-spaniels-genetic.html.
5. Stumbos, John. “Purebred Dogs May Face Health Challenges.” College of Agricultural and Environmental Sciences, 5 Dec. 2020, caes.ucdavis.edu/news/articles/2014/03/purebred-dogs-may-face-health-challenges-1.
6. Sundstrom, Kelly. “The Pros and Cons of Purebred Dogs.” Care.com Resources, 19 May 2021, www.care.com/c/the-pros-and-cons-of-purebred-dogs/.
Comentários