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As special as the Shar Pei looks like because of its wrinkles, as often are the effects of the underlying genetic change discussed.

It should be noted that the following health data refer to the western, not to the Chinese Shar Peis.

 

Genetic basics

Common to all SharPeis is a mutation of a regulatory gene of HAS2 (hyaluronic acid synthetase 2) on chromosome 13. This mutation is present as a so-called CNV (Copy Number Variation), which means that the number of mutations in the individual varies. In all Shar Pei, we can find it at least twice, but may also be present in higher numbers. The more copies that are present, the higher the activity of HAS2 and the more hyaluronic acid is formed and incorporated as a basic substance into the tissue. The skin becomes fainter, thicker, contains more water and produces more wrinkles and a thick muzzle.(1)

Another mutation that is more common in SharPei is a missense mutation in the MTBP gene, also on chromosome 13. This mutation causes a protein that plays a role in inflammatory metabolism to have a "malfunction". The affected dogs often develop a disease with increased inflammatory activity (SPAID = Shar Pei Autoinflammatory Disease). (2)

Furthermore, Shar peis more often than other breeds suffer from a relevant vitamin B12 deficiency. Here, too, a genetic change is probable as the cause, also in a region on chromosome 13. (3)

Some other genetic changes are suspected to be the cause of several more common health disorders.

 

Consequences of genetic changes

SharPei AutoInflammatory Disease (SPAID) and Amyloidosis

The SPAID, commonly referred to simply as "SharPei Fever", is probably the most well-known and dreaded health disorder known to the Shar Pei. This is an auto-inflammatory disease, comparable to the familial Mediterranean fever known in humans, which occurs in about 23% of the western Shar Peis. (7)

Dogs affected by SPAID suffer from episodes of increased inflammatory activity with a high fever that may last for a few hours to days (12 to 36 hours on average). Activation of inflammatory mediators often causes joint and limb pain with swelling of the joints (often of the ankle) and the muzzle. Also abdominal pain, breathing pain and mild nausea and diarrhea may persist. A Shar Pei with a fever rush is usually very ill and often not even able to get up. The symptoms often develop very suddenly and quickly, within less than an hour. First fever episodes usually occur before the 18th month of life, but can be observed in individual cases but also in the old dog for the first time. The frequency and intensity of fever varies widely. While some dogs with only a single episode in life or very short febrile episodes of only a few hours remain fairly unremarkable, others can very often suffer from these episodes with a strong malady.

The main problem of the disease, however, is not even the inflammatory symptoms or the fever, which affect the animals very much, but the associated deposition of protein fragments (type AA amyloid) in the extracellular space (between the cells), the so-called amyloidosis. By storing the amyloid in the internal organs, permanent organ dysfunction and even organ failure occur. In this case, especially the kidney, more rarely the liver is affected. Many diseased Shar Peis die in part relatively early as a result of kidney failure or liver failure. (9)

The therapy consists in a treatment of the acute relapses with pain therapy and fever reduction. Furthermore, a long-term therapy with colchicine is possible with the aim to reduce the severity and frequency of relapses, and to prevent amyloidosis. Of course, an infectious event requiring treatment should be excluded in an acute episode by a veterinary examination.

An appropriate diet and nutritional supplements can additionally help to keep hyaluronic acid production and inflammatory activity under control. Regular (biannual) veterinary check up with controls of renal function, liver function, thyroid function, blood count, vitamin B12 should be done in any case.

Cutaneous mucinosis

In addition to the noticeable skin folds through the thickened, almost bloated skin, the accumulation of hyaluronic acid can also cause blistering on the skin. Especially on the chest and on the legs are numerous small bubbles (so-called mucin bubbles), filled with a water-bright, stringy fluid, the so-called mucin. Occasionally, these blisters may cause itching or rupture, and scratching may sometimes cause inflammation. In itself, the mucin bubbles cause the dog no complaints and are mainly a cosmetic problem.

The soft, thickened skin with its filamentous fluid discharge occasionally causes amazement among owners and veterinarians during operations and wound care, but is a normal phenomenon in the Shar-Pei.

Skin diseases

Heavy wrinkling and Sharpei's increased colonization with yeast fungi can cause skin inflammation and ear infections more frequently. Also for an infestation with demodex mites, a sebhorrhische or an atopic dermatitis the SharPei is more sensitive.

A disease, that can develop in connection with various external causes is immune-mediated neutrophilic vasculitis. This leads to extensive inflammation and necrosis of the skin with fever and pronounced malaise in no time. The fastest possible veterinary treatment with immunosuppressive drugs is required in such cases.

Eye diseases

Pronounced wrinkling in the facial area can lead to curling of the inner eyelids (entropion). Scratching the eyelashes can damage the cornea of the eye. Due to the chronic irritation, the damage can reach as far as deep inflammation and resulting blindness. The earliest possible diagnosis and treatment is very important here. Therapy ranges from regular use of eye ointment to so-called puppy tacking (in which the eyelids are temporarily gathered by means of skin sutures) to corrective surgery to preserve the eyesight. 

Another eye disease that occurs in Shar-Pei is Primary Open-Angle Glaucoma and Lens Luxation (POAG/PLL). Primary open-angle glaucoma (POAG) is a connective tissue disorder in the eye that is often genetic. This means that the water in the chamber cannot drain properly. The resulting increase in internal pressure in the eye puts a strain on the optic nerve and the retina, is very painful for the dog and can ultimately lead to blindness.

Symptoms include dilated pupils, red eyes, cloudy cornea, and increased intraocular pressure. A sharp increase in pressure causes great pain, which can lead to a loss of appetite, scratching of the eyes, rubbing of the head on objects and aggressiveness.
The connective tissue disorder often also causes a luxation of the lens in the eye (PLL).
Most affected dogs become ill around the age of 4-6 years. (8)

Narrowed airways

Although the Shar Pei does not belong to the short-nosed (brachiocephalic) breeds, some Shar Pei suffer from a similar symptom complex, which results from a narrowing of the airways by thickened mucous membranes. The cause here again is the increased hyaluronic acid storage, which leads to a swelling of the tissue. In the affected dogs this leads to a limited performance, poor heat tolerance and an increased risk of anesthesia, as in a brachycephaly syndrome. In some cases, surgical correction of the upper respiratory tract may become necessary.

Hypothyroidism 

Many Shar Peis suffer from hypothyroidism. It is noteworthy that in most cases this is an otherwise rare special form of hypothyroidism, tertiary hypothyroidism. Here, the hypothyroidism is caused by an indirect inhibition of TSH secretion by the increased production of hyaluronic acid. As a result, the healthy thyroid gets no working signal and produces too few hormones. In this case, even with normal or low TSH levels, a thyroid hormone substitution is required in the laboratory for clinical symptoms and low T4. Symptoms may include: skin and coat changes (thin, soft, bleached coat), fatigue, lethargy, irritability, intolerances, weight gain, leg and facial edema, frequent ear infections. Even with Shar Peis without corresponding symptoms, the thyroid function should be checked regularly, since the hypofunction often develops slowly.

Vitamin B12 deficiency

Due to the frequently observed vitamin B12 deficiency in Shar Pei, this value should be regularly monitored in addition to the thyroid levels and renal function, and if necessary a substitution with vitamin B12 should be made. (3)

Immunoglobulin A deficiency

Shar Peis, among others, are more likely to have low levels of IgA in their blood. This change in the immune system leads in the affected dogs to a greater susceptibility to respiratory infections and allergies. (4)

Tumor Diseases

Shar Peis are prone to mast cell mediated diseases and mast cell tumors. Changes in mast cell metabolism and activity favor mast cell-mediated skin inflammatory reactions, allergies, and the appearance of mast cell tumors.

 

References

(1) A novel unstable duplication upstream of HAS2 predisposes to a breed-defining skin phenotype and a periodic fever syndrome in Chinese Shar Pei dogs.
(Olsson et al. PloS Genetics Mar 2011)

(2) Whole genome sequency identifies missense mutation in MTBP in Chinese Shar Pei affected witch autoinflammatory disease (SPAID)
(Metzger J. et al. BMC Genomics 2017)

(3) Association study of Cobalamine deficiency in the Chinese Shar Pei
(Grützner et al. 11/2009 The Journal of Heredity 101)

(4) Genome-wide analysis suggest mechanisms involving early B-Cell development in canine IgA deficiency
(Olsson et al. PloS One. 2015)

(5) Acute febrile neuropath vasculitis of the skin of young Shar Pei dogs
(Malik R. et al. Aust. Vet. J. 2002)

(6) Epidemiological assessment on the risk of canine mast cell tumorbased on the Kiupel two-grade-malignancy classification
(Smiech et al. Acta Vet Scand 2018)

(7) A canine febrile disorder associated with elevated inteleukin-6
(Riva AL et al. Clin Immunol Immunopathol 1992)

(8) Evaluation of ADAMTS17 in Chinese Shar-Pei with primary open-angle glaucoma, primary lens luxation, or both 
Am J Vet Res. 2018 Jan;79(1):98-106.doi: 10.2460/ajvr.79.1.98.

(9) Thorough investigation of a canine autoinflammatory disease (AID) confirms one main risk locus and suggests a modifier locus for amyloidosis 
PLoS One. 2013 Oct 9;8(10):e75242. doi: 10.1371/journal.pone.0075242. eCollection 2013.

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