Yorkshire Terrier Explained

Yorkshire Terrier
Country:	Yorkshire, England
Kc Name:	The Kennel Club
Kc Std:	https://www.thekennelclub.org.uk/services/public/breed/display.aspx?id=6165
Fcistd:	http://www.fci.be/Nomenclature/Standards/086g03-en.pdf

The Yorkshire Terrier, also known as a Yorkie, is a British breed of toy dog of terrier type. It is among the smallest of the terriers and indeed of all dog breeds, with a weight of no more than 3.2kg (07.1lb). It originated in the nineteenth century in the English county of Yorkshire, after which it is named.^[1] The coat is tan on the head and dark steel-grey on the body; no other colour is accepted by either The Kennel Club or the Fédération Cynologique Internationale.

It is a playful and energetic dog, usually kept as a companion dog. It has contributed to the development of other breeds including the Silky Terrier, and also to cross-breeds such as the Yorkipoo.

History

The Yorkshire Terrier originated in Yorkshire. In the mid-nineteenth century, workers from Scotland came to Yorkshire in search of work and brought with them several varieties of terrier dogs. Breeding of the Yorkshire terrier was "principally accomplished by the people – mostly operatives in cotton and woollen mills – in the counties of Yorkshire and Lancashire."^[2] In the 1800s, miners wanting to develop a ratting terrier, bred Black-and-Tan Terriers with the Paisley and Clydesdale Terriers.^[3]

Details are scarce. Mrs A. Foster is quoted as saying in 1886,^[4]

The breed originates from two distinct dogs, a male named Old Crab, a female named Kitty, and another female whose name is not known.^[5] The Paisley Terrier, a smaller version of the Skye Terrier that was bred for a beautiful long silky coat, also figured into the early dogs. Some authorities believed that the Maltese was used as well.^[6] "They were all originally bred from Scotch Terriers (meaning dogs from Scotland, not today's Scottish Terrier) and shown as such the name Yorkshire Terrier was given to them on account of their being improved so much in Yorkshire."

Yorkshire Terriers were shown in a dog show category (class) at the time called "Rough and Broken-coated, Broken-haired Scotch and Yorkshire Terriers". Hugh Dalziel, writing in 1878, says that "the classification of these dogs at shows and in the Kennel Club Stud Book is confusing and absurd" in lumping together these different types.^[7] In the early days of the breed, "almost anything in the shape of a Terrier having a long coat with blue on the body and fawn or silver coloured head and legs, with tail docked and ears trimmed, was received and admired as a Yorkshire Terrier". But in the late 1860s, a popular Paisley-type Yorkshire Terrier show dog named Huddersfield Ben, owned by a woman living in Yorkshire, Mary Ann Foster, was seen at dog shows throughout Great Britain, and defined the breed type for the Yorkshire Terrier.^[8]

Huddersfield Ben

See main article: Huddersfield Ben. Huddersfield Ben was a Yorkshire Terrier whose portrait was painted by George Earl^[9] and in 1891 an authority on the breed wrote, "Huddersfield Ben was the best stud dog of his breed during his lifetime, and one of the most remarkable dogs of any pet breed that ever lived; and most of the show specimens of the present day have one or more crosses of his blood in their pedigree."^[10] A show winner, Huddersfield Ben, through his puppies, helped define the Yorkshire Terrier breed. He is still referred to as "father of the breed".

In North America

The Yorkshire Terrier was introduced in North America in 1872^[11] and the first Yorkshire Terrier was registered with the American Kennel Club (AKC) in 1885.^{[1] [12]} During the Victorian era, the Yorkshire Terrier was a popular pet, and show dog in England, and as Americans embraced Victorian customs, so too did they embrace the Yorkshire Terrier.^[13] The breed's popularity dipped in the 1940s, when the percentage of small breed dogs registered fell to an all-time low of 18% of total registrations.^[14] Smoky, a Yorkshire Terrier and famous war dog from World War II, is credited with beginning a renewal of interest in the breed.^[15] The AKC ranked the Yorkshire Terrier as the 6th most popular purebred in the United States in 2012 and 2013.^[1]

Coat

For adult Yorkshire Terriers, The American Kennel Club places importance on coat colour, quality, and texture.^[16] According to The Kennel Club (UK), the hair must be glossy, fine, straight, and silky. Traditionally the coat is grown out very long and is parted down the middle of the back, but "must never impede movement.".^[17] The hair of the Yorkshire Terrier can be used to determine content of metals in the dog organism.^[18] From the back of the neck to the base of the tail, the coat should be a dark grey to a black colour,^[16] and the hair on the tail should be a darker black.^[17] On the head, high chest and legs, the hair should be a bright, rich tan, darker at the roots than in the middle, that shades into a lighter tan at the tips, but not for all dogs. Also, in adult dogs there should be no black hairs intermingled with any of the tan-coloured fur.^[16] The fine, straight, silky coat is considered hypoallergenic.

Adult Yorkshire Terriers whose coat colours deviate from the standard, or that have woolly or extra fine coats, are still Yorkshire Terriers. The only difference is that it is not recommended to intentionally breed atypical Yorkshire Terriers.^[19] In addition, care may be more difficult for "woolly" or "cottony" textured coats, or coats that are overly fine. Coats may vary in colour. For example, a mature Yorkie may have a silver-blue with light brown, while another might have a black and creamy colour.

The long coat on the Yorkshire Terrier requires regular brushing.^[1]

Hypoallergenic coats

See main article: Hypoallergenic dog breed. The typical fine, straight, and silky Yorkshire Terrier coat has also been listed by many popular dog information websites as being hypoallergenic. In comparison with many other breeds, Yorkies do not shed to the same degree, losing small amounts when bathed or brushed.^[20] The dog's dander and saliva typically trigger allergic reactions.^[21] Allergists recognise that at times a particular allergy patient will be able to tolerate a particular dog, but they agree that "the luck of the few with their pets cannot be stretched to fit all allergic people and entire breeds of dogs."^[22] The Yorkshire Terrier coat is said to fall out only when brushed or broken, or just said to not shed.^[23] Although neither of those statements agree with what biologists, veterinarians, and allergists know about dog fur, allergists "think there really are differences in protein production between dogs that may help one patient and not another".^[22]

Other colours

The Yorkshire Terrier is a tan dog with a blue saddle. Particolours exist, although they are not correct for the breed standard. The particolour coat is white with black-blue and tan. The white is caused by the recessive piebald gene. It is very rare to get a particolour, and if one is found, it tends to be very expensive.^[24] Some Yorkshire Terriers are solid golden, they only produce pheomelanin, others are liver or chocolate, a brown colour; they produce brown eumelanin instead of black eumelanin.^{[25] [26]} The standard prescribes clearly defined fur-colours, and non-standard colours may indicate crossbreeding with other breeds or in rare cases even health problems. The AKC registration form for Yorkshire Terriers allows for four choices: blue and tan, blue and gold, black and tan, black and gold. Colour alone will not affect whether or not a dog is a good companion and pet. Even though off-coloured Yorkshire Terriers are advertised at premium prices, being of an unusual or atypical colour is stated to be neither new, desirable, nor exotic.

Mismatched Yorkshire Terriers should not be crossed with the Biewer Terrier, a new breed that originated in Germany.^[27] Although the AKC will not deny registration of a Yorkshire Terrier on colour alone, meaning that particolours are now registerable with the AKC, the Yorkshire Terrier Club of America has a directive that "any solid colour or combination of colours other than black and tan" for adult dogs is a disqualification, and "dogs of solid colour, unusual combination of colours, and particolours should be disqualified."^[28]

Puppy coats

It may take three or more years for the coat to reach its final colour. The final colour is usually a black or greyish colour. P. H. Combs, writing in 1891, complained about show wins awarded to puppies, when the dog's coat does not fully come in until three or four years old, "and the honour of winning such a prize (for a puppy) can therefore be of but little practical benefit to the owner" since the adult dog's colour cannot be exactly predicted.^{[29] [30]}

Coat care

Owners may trim the hair short for easier care. For shows, the coat is left long, and may be trimmed to floor length to give ease of movement and a neater appearance. Hair on the feet and the tips of ears can also be trimmed. The traditional long coat is extremely high maintenance. The coat might get knotted if not brushed daily (a bristle brush for short and shaved coat and a pin brush for long coat). In order to prevent breakage, the coat may be wrapped in rice paper, tissue paper or plastic, after a light oiling with a coat oil. The oil has to be washed out once a month and the wraps must be fixed periodically during the week to prevent them from sliding down and breaking the hair. Elaborate coat care dates from the earliest days of the breed. In 1878, John Walsh described similar preparations: the coat is "well greased" with coconut oil, the dog is bathed weekly, and the dog's feet are "carefully kept in stockings".^[31]

Temperament

The ideal Yorkshire Terrier character or "personality" has been described by the Kennel Club as having a "carriage very upright conveying an important air".

Yorkshire Terriers are ranked 34th in Stanley Coren's The Intelligence of Dogs.^[32]

Health

Health issues often seen in the Yorkshire Terrier include bronchitis, lymphangiectasia, portosystemic shunt, cataracts, and keratitis sicca.^[33] Additionally, Yorkies often have a delicate digestive system, with vomiting or diarrhoea resulting from consumption of foods outside of a regular diet.^[34] The relatively small size of the Yorkshire Terrier means that it usually has a poor tolerance for anaesthesia. Additionally, a toy dog such as the Yorkie is more likely to be injured by falls, other dogs, and owner clumsiness.^[34]

The Yorkshire Terrier has an above average life expectancy. A 2013 study in the UK of patient records found the breed to have a life expectancy of 13 years, higher than the average.^[35] A similar 2022 study in the UK found the breed to have a life expectancy of 12 and a half years.^[36] A 2024 UK study found a life expectancy of 13.3 years for the breed compared to an average of 12.7 for purebreeds and 12 for crossbreeds.^[37] A study in Japan based on pet cemetery data found a life expectancy of 14.3 years, above the average life expectancy.^[38] A 2024 Italian study found a life expectancy of 13 years for the breed compared to 10 years overall.^[39]

Colour dilution alopecia, a form of alopecia associated with blue colour coats is common in the Yorkshire Terrier.^[40]

Health conditions that can be found in Yorkshire Terriers, include distichiasis, hydrocephalus, hypoplasia of dens, Legg–Calvé–Perthes syndrome, luxating patella, portosystemic shunt, retinal dysplasia, and bladder stones.^[41] The following are other health conditions that affect the breed:

• Distichiae, eyelashes arising from an abnormal spot (usually the duct of the meibomian gland at the edge of the eyelid), are often found in Yorkies.^[42] Distichiae can irritate the eye and cause tearing, squinting, inflammation, corneal abrasions or corneal ulcers, and scarring. Treatment options may include manual removal, electrolysis, or surgery.
• Hypoplasia of dens is a non-formation of the pivot point of the second cervical vertebra, which leads to spinal cord damage.^[41] Onset of the condition may occur at any age, producing signs ranging from neck pain to quadriplegia.^[43]
• Legg–Calvé–Perthes syndrome, which causes the top of the femur (thigh bone) to degenerate, occurs in Yorkies in certain lines.^[44] The condition appears to result from insufficient circulation to the area around the hip joint. As the blood supply is reduced, the bone in the head of the femur collapses and dies and the cartilage coating around it becomes cracked and deformed.^[44] Usually the disease appears when the Yorkie is young (between five and eight months of age); signs are pain, limping or lameness.^[45] The standard treatment is surgery to remove the affected part of the bone.^[45] Following surgery, muscles hold the femur in place and fibrous tissue forms in the area of removal to prevent bone rubbing on bone.^[46] Although the affected leg will be slightly shorter than prior to surgery, the Yorkie may regain almost normal use.^[45]
• Luxating patellas (slipping kneecaps) are another common defect considered to be genetic in Yorkies, although it may also be caused by an accidental fall. Weak ligaments and tendons in the knee or malformed (too shallow) patellar grooves, allow the patella to slip out of its groove sideways.^[47] This causes the leg to 'lock up' with the foot held off the ground.^[47] A dog with this problem may experience frequent pain and lameness, or may be bothered by it only on occasion. Over time, the patellar ridges can become worn down, making the groove even more shallow and causing the dog to become increasingly lame.^[47] Surgery is the main treatment option available for luxating patellas, although it is not necessary for every dog with the condition. The severity of luxating patellas are on a scale of 1 to 4, with 4 being the most severe. Many dogs will not develop past a stage 1 or 2.
• Portosystemic shunt, a congenital malformation of the portal vein (which brings blood to the liver for cleansing), is also common in Yorkies. In this condition some of the dog's blood bypasses the liver and the "dirty" blood goes on to poison the heart, brain, lungs and other organs with toxins. A Yorkie with this condition might exhibit a wide variety of symptoms, such as small stature, poor appetite, weak muscle development, decreased ability to learn, inferior coordination, occasional vomiting and diarrhoea, behavioral abnormalities, seizures (especially after a meal) and blindness, which could lead to a coma and death. Often, the shunt can be treated with surgery.^[48]

• Tracheal collapse, caused by a progressive weakening of the walls of the trachea, occurs in many toy breeds, especially very tiny Yorkies.^[49] As a result of genetics, the walls of the trachea can be flaccid, a condition that becomes more severe with age. Cushing's syndrome, a disorder that causes production of excess steroid hormone by the adrenal glands, can also weaken cartilage and lead to tracheal collapse.^[50] There is a possibility that physical strain on the neck might cause or contribute to trachea collapse. Since this is usually caused by an energetic Yorkie pulling against his collar, many veterinarians recommend use of a harness for leashed walks.^[49] An occasional "goose honking" cough, especially on exertion or excitement, is usually the first sign of this condition.^[49] Over time, the cough may become almost constant in the Yorkie's later life. Breathing through the obstruction of a collapsed (or partially collapsed) trachea for many years can result in complications, including chronic lung disease. The coughing can be countered with cough suppressants and bronchodilators.^[49] If the collapse is advanced and unresponsive to medication, sometimes surgery can repair the trachea.^[49]

A UK study found the Yorkshire Terrier to be 6.79 times more likely to acquire impaired hepatic perfusion compared to other dogs.^[51]

Hypoglycaemia

Low blood sugar in puppies, or transient juvenile hypoglycaemia, is caused by fasting (too much time between meals).^[52] In rare cases, hypoglycaemia may continue to be a problem in mature, usually very small, Yorkies. It is often seen in Yorkie puppies at 5 to 16 weeks of age.^[52] Very tiny Yorkie puppies are especially predisposed to hypoglycaemia because a lack of muscle mass makes it difficult to store glucose and regulate blood sugar.^[52] Factors such as stress, fatigue, a cold environment, poor nutrition, and a change in diet or feeding schedule may bring on hypoglycaemia.^[53] Low blood sugar can also be the result of a bacterial infection, parasite or portosystemic liver shunt.^[54] Hypoglycaemia causes the puppy to become drowsy, listless (glassy-eyed), shaky, uncpoglycaemic attack, the puppy usually has very pale or grey gums.^[55] The puppy also may not eat unless force-fed.^[52] Hypoglycaemia and dehydration seem to go hand-in-hand, and force-feeding or injecting fluids may also be necessary. Additionally, a hypoglycaemic Yorkie may have a lower than normal body temperature and, in extreme cases, may have a seizure or go into a coma.^[56] A dog showing symptoms should be given sugar in the form of corn syrup or Nutri-Cal and be treated by a veterinarian immediately, as prolonged or recurring attacks of hypoglycaemia can permanently damage the dog's brain.^[56] In severe cases, it can be fatal.^[52]

The Yorkshire Terrier is one of the more commonly affected breeds for progressive rod-cone degeneration. An autosomal recessive mutation in the PRCD gene is responsible for the condition in the breed.^[57]

Docking and Cropping

See main article: Docking (dog). Traditionally, the Yorkshire Terrier's tail is docked to a medium length.^[58] Opposition to this practice began very early in the history of the breed; Hugh Dalziel, writing about Yorkshire Terriers in 1878, declared that "There is no reason for mutilating pet dogs, and perfect ears and tails should be bred, not clipped into shape with scissors." AKC and Canadian Kennel Club still require the Yorkie's tail be docked in order to compete at its events. The majority of the rest of the world has adopted a "no docking/no cropping" rule.

Related breeds and derived breeds

The Yorkshire Terrier breed descends from larger but similar Scottish breeds, such as the Skye Terrier and the now-extinct Paisley Terrier. In its turn, other breeds have been created from the Yorkshire Terrier, such as the Silky Terrier. Demand for unusual pets has resulted in high prices being paid for Yorkshire Terriers crossed with various other breeds, which are described with a portmanteau word made up of syllables (or sounds) from Yorkshire Terrier and the breed name of the other parent. Some of these such portmanteau-named crosses can be found on the list of dog crossbreeds.

The Biewer Terrier, bred from blue, white and gold puppies named Schneeflocke and Schneeflöckchen von Friedheck,^{[59] [60] [61]} owned by Mr. and Mrs. Biewer in Germany,^[62] was once considered a variation of the Yorkshire Terrier but has since been recognised as a separate breed by many kennel clubs, including the AKC.^[63]

Notable Yorkshire Terriers

• In 1997, Champion Ozmilion Mystification became the first Yorkie to win Best in Show at Crufts, the world's largest annual dog show.^{[64] [65]}
• Sylvia, a matchbox-sized Yorkshire Terrier owned by Arthur Marples of Blackburn, England, was the smallest dog in recorded history. The dog died in 1945 when she was two years old, at which point she stood tall at the shoulder, measured from nose tip to tail, and weighed .^{[66] [67]}
• Smoky, a war dog and hero of World War II, was owned by William Wynne of Cleveland, Ohio. Wynne adopted Smoky while he was serving with the 5th Air Force in the Pacific.^[68]
• Pasha, Tricia Nixon Cox's pet Yorkie, lived in the White House during Richard Nixon's presidency.^[69]

Notes

1.The Japanese study reviewed cemetery data which is unlikely to have any records of still-births and altricial deaths whilst a veterinary clinic likely would have data on these.

Notes and References

1. http://www.akc.org/dog-breeds/yorkshire-terrier/#standard "Get to Know the Yorkshire
2. P. H. Combs in The American Book of the Dog, pg 443, edited by G. O. Shields, Rand, McNally & Company, Publishers, Chicago and New York 1891 no ISBN
3. Book: Fogle, Bruce . 2000 . The New Encycyclopedia of Dog . USA . Dorling Kindersley . 272 . 0-7894-6130-7 .
4. Mrs A Foster of Bradford, England, quoted by James Watson in the Century Magazine in 1886; on page 441 of The American Book of the Dog, pg 454, edited by G. O. Shields, Rand, McNally & Company, Publishers, Chicago and New York 1891, no ISBN
5. 1885 article by Ed. Bootman of Halifax, England was printed in The Stock-Keeper, detailing the breed's origins, discussed pg 441-442 The American Book of the Dog, edited by G. O. Shields, Rand, McNally & Company, Publishers, Chicago and New York 1891 no ISBN
6. British dogs, their points, selection, and show preparation, by William D. Drury, pg 582 published 1903, L. Upcott Gill, London, and Charles Scribner's Sons, New York (no ISBN) Quote: "I think the Yorkshire gets the softness and length of coat due to Maltese blood".
7. quoted in The dogs of the British Islands, by John Henry Walsh, The Field, publisher, 1878, Third Edition, pg 213
8. Book: Clark. Anne Rogers. Anne Rogers Clark. The International Encyclopedia of Dogs . Andrew H. . Brace . Howell Book House. 1995. 484. 0-87605-624-9.
9. 2006 art exhibition catalogue "Best in Show, the Dog in Art from the Renaissance to Today", notes by Edgar Peters Bowron, Yale University Press,
10. P. H. Combs in The American Book of the Dog, pg. 454, edited by G. O. Shields, Rand, McNally & Company, Publishers, Chicago and New York 1891 no ISBN
11. Web site: Weston . Lee . Yorkshire Terrier History . wordofpoochs.blogspot.com. 1 October 2019.
12. Book: Caroline Coile, D.. The Yorkshire Terrier Handbook. 2003. Barron's Educational Series Inc.. Hauppauge, New York, USA. 5. registration. first Yorkshire Terrier was registered with the American Kennel Club (AKC) in 1885.. 978-0-7641-2585-0.
13. Web site: Yorkshire Terrier. Yahoo! Pets. 22 December 2010. https://web.archive.org/web/20070329052239/http://pets.yahoo.com/pets/dogs/breed/yorkshire_terrier. 29 March 2007.
14. News: Yorkies Have Their Year! Tiny Toy Overtakes Venerable Favorites - Golden Retriever and German Shepherd - as Second Most Popular Dog in America . AKC News . 7 January 2007 . 25 February 2007.
15. News: Special Issue: Yorkshire Terrier . Popular Dog Magazine . 2001.
16. Web site: Yorkshire Terrier (Yorkie) Dog Breed Information. akc.org. 15 April 2018.
17. Web site: Kennel Club Standard. https://web.archive.org/web/20070211152201/http://www.thekennelclub.org.uk:80/item/199. dead. 11 February 2007. 17 July 2022.
18. Kosla, T., & Skibniewska, E. M. (2010). The content of aluminum in the hair of Yorkshire terrier dogs from the Warsaw area depending on sex, age and keeping conditions. Trace Elements & Electrolytes, 27(4), 209–213.
19. Web site: Parti-Color Yorkshire Terriers?. https://web.archive.org/web/20090318222408/http://www.ytca.org/faq.html#B. dead. 18 March 2009. www.theyorkshireterrierclubofamerica.org. 17 July 2022.
20. http://www.entdocs.org/catallergy.htm Jeffrey Adelglass, M.D., ear, nose, throat and allergy information
21. Web site: Pet allergy - Symptoms and causes. mayoclinic.com. 15 April 2018.
22. Web site: Nonallergenic Dog? Not Really . Denise . Grady . . 5 February 1997 . 1 February 2014.
23. Web site: Wash . John . Yorkshire Terrier . NetPets . 21 February 2007.
24. Web site: What Is A RESPONSIBLE BREEDER . https://web.archive.org/web/20090318222408/http://www.ytca.org/faq.html#C. dead. Shirley Patterson Secretary of the YTCA . 18 March 2009. www.theyorkshireterrierclubofamerica.org. 17 July 2022.
25. Web site: Bowling. Sue. Coat Color Genetics - Brown Locus. Sue Ann Bowling.
26. Genomia: Yorkshire Terrier coat colours
27. Web site: December 28, 2020. The Biewer Terrier Was Developed in Germany by Werner and Gertrude Biewer, Making Its Debut in Germany in 1986. The Biewer Terrier was introduced in America in 2003.. biewerterrierclubofamerica.org.
28. Web site: Carl C. Yochum, President. https://web.archive.org/web/20090328030803/http://www.ytca.org/mainview.htm. dead. 28 March 2009. www.theyorkshireterrierclubofamerica.org. 17 July 2022.
29. The American book of the Dog, edited by G. O. Shields, Rand, McNally & Company, Publishers, Chicago and New York, 1891, no ISBN. Section on the Yorkshire written by P. H. Combs
30. Web site: Official Standard of the Yorkshire Terrier . Yorkshire Terrier Club of America . 29 January 2015.
31. The Dogs of the British Islands, pg 212, by John Henry Walsh, The Field publisher, 1878, Third Edition
32. Book: Coren, Stanley. The Intelligence of Dogs . 2006. Pocket Books. London, UK. 978-1-4165-0287-6.
33. Lane, Marion (2001). The Yorkshire Terrier: An Owner's Guide to a Happy Healthy Pet, Second Edition, Howell Book House - Wiley Publishing, Inc., .
34. Web site: Schultz. Jacque Lynn . 2004. https://web.archive.org/web/20041230234816/http://www.petfinder.com/journalindex.cgi?path=/public/breeds/dogbreeds/1.4.28.txt&template=templateprint.html. 30 December 2004. The Terrier Tyke With a Big Attitude. ASPCA. 10 March 2007.
35. O’Neill . D. G. . Church . D. B. . McGreevy . P. D. . Thomson . P. C. . Brodbelt . D. C. . Longevity and mortality of owned dogs in England . 10.1016/j.tvjl.2013.09.020 . The Veterinary Journal . 2013 . 24206631. 198 . 3 . 638–43. https://web.archive.org/web/20191231022919/https://researchonline.rvc.ac.uk/id/eprint/7826/1/7826.pdf . 31 December 2019.
36. Teng . Kendy Tzu-yun . Brodbelt . Dave C. . Pegram . Camilla . Church . David B. . O’Neill . Dan G. . Life tables of annual life expectancy and mortality for companion dogs in the United Kingdom . Scientific Reports . Springer Science and Business Media LLC . 12 . 1 . 2022-04-28 . 2045-2322 . 10.1038/s41598-022-10341-6 . 6415. 35484374 . 9050668 . 2022NatSR..12.6415T .
37. McMillan . Kirsten M. . Bielby . Jon . Williams . Carys L. . Upjohn . Melissa M. . Casey . Rachel A. . Christley . Robert M. . Longevity of companion dog breeds: those at risk from early death . Scientific Reports . Springer Science and Business Media LLC . 14 . 1 . 2024-02-01 . 2045-2322 . 10.1038/s41598-023-50458-w . 10834484 .
38. INOUE . Mai . KWAN . Nigel C. L. . SUGIURA . Katsuaki . Estimating the life expectancy of companion dogs in Japan using pet cemetery data . Journal of Veterinary Medical Science . Japanese Society of Veterinary Science . 80 . 7 . 2018 . 0916-7250 . 10.1292/jvms.17-0384 . 1153–1158. 29798968 . 6068313 .
39. Roccaro . Mariana . Salini . Romolo . Pietra . Marco . Sgorbini . Micaela . Gori . Eleonora . Dondi . Maurizio . Crisi . Paolo E. . Conte . Annamaria . Dalla Villa . Paolo . Podaliri . Michele . Ciaramella . Paolo . Di Palma . Cristina . Passantino . Annamaria . Porciello . Francesco . Gianella . Paola . Guglielmini . Carlo . Alborali . Giovanni L. . Rota Nodari . Sara . Sabatelli . Sonia . Peli . Angelo . Factors related to longevity and mortality of dogs in Italy . Preventive Veterinary Medicine . 225 . 2024 . 10.1016/j.prevetmed.2024.106155 . 106155. free . 11585/961937 . free .
40. Book: Rhodes . Karen Helton . Werner . Alexander H. . Blackwell's Five-Minute Veterinary Consult Clinical Companion . Wiley-Blackwell . Ames, Iowa . 2011-01-25 . 978-0-8138-1596-1 . 58.
41. Web site: Hereditary and Congenital Diseases of Purebred Dogs . Kansas State University . 13 March 2007 . dead . https://web.archive.org/web/20070221132319/http://www.vet.ksu.edu/studentorgs/Therio/pdf/Hereditary_Congenital.pdf . 21 February 2007 .
42. News: Schultz . Jacque Lynn . The Terrier Tyke With a Big Attitude . ASPCA . 2004 . 10 March 2007 . dead . https://web.archive.org/web/20041230234816/http://www.petfinder.com/journalindex.cgi?path=/public/breeds/dogbreeds/1.4.28.txt&template=templateprint.html . 30 December 2004 .
43. Web site: Linville . Robert L. . Breed Predisposition to Disease and Congenital Conditions . Dr. Bob's All Creatures Site . 6 March 2006 . 13 March 2007.
44. Web site: Degner . Danial . Legg-Calve-Perthes disease (or Legg-Perthes disease) . Vet Surgery Central Inc. . 2004 . 4 March 2007.
45. Web site: Voit . Pam . Legg Perthe's Disease: What you Should Know . 4 March 2007 . 1 July 2022 . https://web.archive.org/web/20220701015204/http://www.ahtluvr.com/ahtleggperthes.html . dead .
46. Web site: Degner . Danial . Femoral Head and Neck Excision . Vet Surgery Central Inc. . 2004 . 4 March 2007.
47. Web site: Foster . Race . Smith . Marty . Luxating Patella . PetEducation.com . 2007 . 5 March 2007.
48. Web site: Portosystemic Shunt . Genetic Welfare Problems of Companion Animals . Universities Federation for Animal Welfare . ufaw.org.uk . 10 February 2015 . dead . https://web.archive.org/web/20150211131100/http://www.ufaw.org.uk/PORTOSYSTEMICSHUNTYORKSHIRETERRIER.php . 11 February 2015 .
49. Web site: Degner . Danial . Tracheal Collapse . Vet Surgery Central Inc. . 2004 . 4 March 2007.
50. Web site: Cushing's Disease & the Cavalier King Charles Spaniel. cavalierhealth.net. 15 April 2018.
51. Bandara . Y. . Bayton . W. A. . Williams . T. L. . Scase . T. . Bexfield . N. H. . Histopathological frequency of canine hepatobiliary disease in the United Kingdom . Journal of Small Animal Practice . 62 . 9 . 2021 . 0022-4510 . 10.1111/jsap.13354 . 730–736.
52. Web site: Hypoglycemia symptoms and treatment . Go Pets America . 10 March 2007.
53. Web site: O'Neil . Jacqueline . Dealing with Your Chihuahua's Health Issues (Adapted from Chihuahuas for Dummies) . Dummies.com . 2007 . 10 March 2007.
54. Web site: Brooks . Wendy C. . Toy Breed Hypoglycemia . VeterinaryPartner.com . 31 July 2005 . 10 March 2007.
55. Web site: 系统发生错误. www.yorkiesllc.com. 17 July 2022.
56. Web site: Weston . Lee . Hypoglycemia . Pomeranian Club of Canada . 10 March 2007.
57. Book: James A.C. . Oliver . Cathryn S. . Mellersh . Barbara . Cooper . Elizabeth . Mullineaux . Lynn . Turner . BSAVA Textbook of Veterinary Nursing . 2020 . British Small Animal Veterinary Association . 978-1-910-44339-2 . Sixth. Genetics. 131.
58. Web site: FCI-Standard . 7 September 2012 . dead . https://web.archive.org/web/20120831162939/http://www.fci.be/uploaded_files/086gb2009_en.doc . 31 August 2012 .
59. Pedigree Online: Schneeflocke von Friedheck
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