Title: Dog skin disorders

{{Short description|Group of illnesses affecting canines}}
'''Skin disorders''' are among the most common health problems in [[dog]]s, and have many causes. The condition of a dog's skin and coat is also an important indicator of its general health. Skin disorders of dogs vary from acute, self-limiting problems to chronic or long-lasting problems requiring life-time treatment. Skin disorders may be primary or secondary (due to scratching, itch) in nature, making diagnosis complicated.

==Immune-mediated skin disorders==
Skin disease may result from deficiency or overactivity of immune responses. In cases where there are insufficient immune responses, the disease is usually described by the secondary disease that results. Examples include increased susceptibility to [[demodectic mange]] and recurrent skin infections, such as [[Malassezia]] infection or bacterial infections. Increased but harmful immune responses can be divided into hypersensitivity disorders such as [[atopic dermatitis]] and autoimmune disorders ([[autoimmunity]]), such as [[pemphigus]] and [[canine discoid lupus erythematosus|discoid lupus erythematosus]].&lt;ref name=&quot;:5&quot; /&gt;&lt;ref&gt;{{Cite web|url=https://todaysveterinarynurse.com/articles/dermatology-immune-mediated-skin-disorders-of-dogs/|title=Immune-Mediated Skin Disorders of Dogs|website=Today's Veterinary Nurse|language=en|access-date=2019-11-17}}&lt;/ref&gt;

===Atopic dermatitis===
[[Image:Canine Atopy.jpg|thumb|Dog with atopic dermatitis, with signs around the eye created by rubbing.]]
[[Atopy]] is a hereditary&lt;ref&gt;{{cite journal|last=Shaw|first=Stephen|author2=Wood, J.L. |author3=Freeman, J. |author4=Littlewood, J.D. |author5=Hannant, D. |title=Estimation of heritability of atopic dermatitis in Labrador and Golden Retrievers|journal=American Journal of Veterinary Research|year=2004|volume=65|issue=7|pages=1014–1020 |doi=10.2460/ajvr.2004.65.1014|pmid=15281664 |doi-access=free}}&lt;/ref&gt; and chronic (lifelong) allergic skin disease. Signs usually begin between 6 months and 3 years of age, with some breeds of dog, such as the [[golden retriever]], showing signs at an earlier age. Dogs with atopic dermatitis are itchy, especially around the eyes, muzzle, ears and feet. In severe cases, the irritation is generalised. If the allergens are seasonal, the signs of irritation are similarly seasonal. Many dogs with house [[dust mite allergy]] have [[perennial]] disease.&lt;ref&gt;{{cite journal|last=Favrot|first=Claude|author2=Steffan, J. |author3=Seewald, W. |author4=Picco, F. |title=A prospective study on the clinical features of chronic canine atopic dermatitis and its diagnosis|journal=Veterinary Dermatology|year=2010|volume=21|issue=1|pages=23–31 |doi=10.1111/j.1365-3164.2009.00758.x|pmid=20187911}}&lt;/ref&gt; Some of the [[allergens]] associated with atopy in dogs include [[pollens]] of trees, grasses and weeds, as well as molds and [[house dust mite]]s. Ear and skin infections by the bacteria ''Staphylococcus pseudintermedius'' and the yeast ''[[Malassezia pachydermatis]]'' are commonly secondary to atopic dermatitis.&lt;ref name=&quot;Gedon2018&quot;&gt;{{cite journal | last=Gedon | first=Natalie Katharina Yvonne | last2=Mueller | first2=Ralf Steffen | title=Atopic dermatitis in cats and dogs: a difficult disease for animals and owners | journal=Clinical and Translational Allergy | volume=8 | issue=1 | date=2018 | issn=2045-7022 | pmid=30323921 | pmc=6172809 | doi=10.1186/s13601-018-0228-5 | doi-access=free | page=}}&lt;/ref&gt;

Dogs with the condition often present with [[erythema]]. The [[axillae]], ventral [[abdomen]], distal extremities, inner [[Pinna (anatomy)|pinnae]]; and periocular, perioral, and perianal regions are commonly affected. Pruritus and inflammation may result in self-induced [[alopecia]] and [[excoriation]]. [[Otitis externa]] is present in half of all dogs with atopic dermatitis.&lt;ref name=&quot;Gedon2018&quot;/&gt;

Food allergy can be associated with identical signs and some authorities consider [[Dog Food Allergies|food allergy]] to be a type of atopic dermatitis.&lt;ref&gt;{{cite journal|last=Picco|first=F |author2=Zini, E. |author3=Nett, C. |author4=Naegeli, C. |author5=Bigler, B. |author6=Rufenacht, S. |author7=Roosje, P. |author8=Gutzwiller, M.E. |author9=Wilhelm, S. |author10=Pfister, J. |author11=Meng, E. |author12=Favrot, C.|title=A prospective study on canine atopic dermatitis and food-induced allergic dermatitis in Switzerland|journal=Veterinary Dermatology|year=2008|volume=19|issue=3 |pages=150–155|doi=10.1111/j.1365-3164.2008.00669.x|pmid=18477331 |url=https://www.zora.uzh.ch/id/eprint/163742/1/20080362_001986015.pdf }}&lt;/ref&gt; Food allergy can be identified through the use of elimination diet trials in which a novel or hydrolysed protein diet is used for a minimum of 6 weeks.

Diagnosis of atopic dermatitis is by elimination of other causes of irritation, including fleas, mites, and other parasites, such as ''[[Cheyletiella]]'' and lice. Allergies to aeroallergens can be identified using intradermal allergy testing and/or blood testing (allergen-specific IgE [[ELISA]]).

Treatment includes avoidance of the offending allergens if possible, but for most dogs this is not practical or effective. Other treatments modulate the adverse immune response to allergens and include antihistamines, steroids, ciclosporin, and immunotherapy (a process in which allergens are injected to try to induce tolerance).&lt;ref&gt;{{cite journal|last=Olivry|first=Thiery|author2=Foster, A.P. |author3=Mueller, R.S. |author4=McEwan, N.A. |author5=Chesney, C. |author6=Williams, H.C. |title=Interventions for atopic dermatitis in dogs: a systematic review of randomized controlled trials|journal=Veterinary Dermatology|year=2010|volume=21|issue=1|pages=4–22 |doi=10.1111/j.1365-3164.2009.00784.x|pmid=20187910|doi-access=free}}&lt;/ref&gt; In many cases, shampoos, medicated wipes and ear cleaners are needed to try to prevent the return of infections.

===Autoimmune skin diseases===
Pemphigus foliaceus is the most common autoimmune disease of the dog.&lt;ref name=&quot;:5&quot;&gt;{{Cite web|url=http://vcahospitals.com/know-your-pet/autoimmune-skin-disease-in-dogs|title=Autoimmune Skin Disease in Dogs|website=vca_corporate|language=en|access-date=2019-11-17}}&lt;/ref&gt; Blisters in the epidermis rapidly break to form crusts and erosions, most often affecting the face and ears initially, but in some cases spreading to include the whole body. The paw pads can be affected, causing marked hyperkeratosis (thickening of the pads with scale). Other autoimmune diseases include bullous pemphigoid and epidermolysis bullosa acquisita.

Treatment of [[autoimmune skin diseases in dogs]] requires methods to reduce the abnormal immune response; steroids, [[azathioprine]] and other drugs are used as immunosuppressive agents.&lt;ref name=&quot;:5&quot; /&gt;

==Physical and environmental skin diseases==
===Hot spots===
{{main|Hot spot (veterinary medicine)}}
A hot spot, or ''acute moist dermatitis'', is an acutely inflamed and infected area of skin irritation created and made worse by a dog licking and biting at itself. A hot spot can manifest and spread rapidly in a matter of hours, as secondary ''[[Staphylococcus]]'' infection causes the top layers of the skin to break down and pus becomes trapped in the hair. Hot spots can be treated with [[corticosteroid]] medications and oral or topical [[antibiotic]] applications, as well as clipping hair from around the lesion. Underlying causes include [[flea allergy dermatitis]] or other allergic skin diseases. Dogs with thick undercoats are most susceptible to developing hot spots.&lt;ref&gt;{{Cite web|url=https://www.pethealthnetwork.com/dog-health/dog-diseases-conditions-a-z/hot-spots-dogs|title=Hot Spots in Dogs|website=Pet Health Network|language=en|access-date=2019-11-17}}&lt;/ref&gt;

===Acral lick granulomas===
[[File:Canine lick granuloma.jpg|right|thumb|[[Lick granuloma]] from excessive licking]]
[[Lick granuloma]]s are raised, usually ulcerated areas on a dog's extremity caused by the dog's own incessant, [[compulsive]] licking. Compulsive licking is defined as licking in excess of that required for standard grooming or exploration, and represents a change in the animal's typical behavior and interferes with other activities or functions (e.g., eating, drinking, playing, interacting with people) and cannot easily be interrupted.&lt;ref&gt;{{cite web | title = Treatment of other Canine Behavioral Problems | work = The Merck Veterinary Manual | year = 2008 | url = http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/140217.htm| access-date = 2009-01-28 }}&lt;/ref&gt;

==Infectious skin diseases==
[[Image:Dogmangeeee.jpg|thumb|250px|right|A dog with skin irritation and hair loss on its leg caused by [[demodectic mange]]]]
Infectious skin diseases of dogs include contagious and non-contagious infections or infestations. Contagious infections include parasitic, bacterial, fungal and viral skin diseases.

One of the most common contagious parasitic skin diseases is [[Sarcoptic mange]] (scabies). Another is mange caused by [[Demodex]] mites ([[Demodicosis]]), though this form of mange is not contagious. Another contagious infestation is caused by a [[mite]], ''[[Cheyletiella]]''. Dogs can be infested with contagious [[lice]].

Other ectoparasites, including [[flea]] and [[tick]] infestations are not considered directly contagious but are acquired from an environment where other infested hosts have established the parasite's life cycle.

[[Ringworm]] is a fungal infection that can be contagious to other dogs as well as humans.&lt;ref&gt;{{Cite web|title=Disease risks for dogs in social settings|url=https://www.avma.org/resources-tools/pet-owners/petcare/disease-risks-dogs-social-settings|access-date=2021-09-19|website=American Veterinary Medical Association|language=en}}&lt;/ref&gt; It is one of the most frequent skin diseases.&lt;ref&gt;{{cite journal |last1=Chermette |first1=René |last2=Ferreiro |first2=Laerte |last3=Guillot |first3=Jacques |title=Dermatophytoses in Animals |journal=Mycopathologia |date=November 2008 |volume=166 |issue=5–6 |pages=385–405 |id={{ProQuest|221133406}} |doi=10.1007/s11046-008-9102-7 |pmid=18478363 |s2cid=9294569 }}&lt;/ref&gt; A dog can become infected by direct contact with another infected dog, brushing up against a surface that an infected dog has touched,&lt;ref name=ring&gt;{{Cite web|date=May 24, 2021|first=Anna|last=Burke|title=Ringworm in Dogs—Symptoms, Treatment, and Prevention|url=https://www.akc.org/expert-advice/health/ringworm-in-dogs/|access-date=2021-09-30|website=American Kennel Club|language=en}}&lt;/ref&gt; as well as coming in contact with species of ringworm that live in the soil.&lt;ref name=&quot;Ringworm in Dogs&quot;&gt;{{Cite web|title=Ringworm in Dogs|url=https://www.petmd.com/dog/conditions/skin/c_dg_dermatophytosis|access-date=2021-09-30|website=www.petmd.com|language=en}}&lt;/ref&gt; Ringworm is round,&lt;ref&gt;{{Cite web|title=Disease risks for dogs in social settings|url=https://www.avma.org/resources-tools/pet-owners/petcare/disease-risks-dogs-social-settings|access-date=2021-09-30|website=American Veterinary Medical Association|language=en}}&lt;/ref&gt; or ringed&lt;ref name=&quot;Remedies for Dog Ringworm&quot;&gt;{{Cite web|title=Remedies for Dog Ringworm|url=https://pets.webmd.com/dogs/dog-ringworm-remedies|access-date=2021-09-30|website=WebMD|language=en}}&lt;/ref&gt; in shape. Symptoms of ringworm can include hair loss on the sections of the infected area(s),&lt;ref name=&quot;Ringworm in Dogs&quot;/&gt; itchiness (may or may not occur),&lt;ref name=ring/&gt; Ringworm tends to occur more in puppies than adult dogs.&lt;ref name=&quot;Remedies for Dog Ringworm&quot;/&gt; Ringworm is not a life-threatening condition but a veterinarian visit is usually needed in order to confirm the diagnosis and be prescribed a topical or oral medication for the ringworm.&lt;ref name=ring/&gt;
[[Image:Dog with Malassezia dermatitis.JPG|thumb|Dog with dermatitis caused by Malassezia (yeast)]]Non-contagious skin infections can result when normal bacterial or fungal [[skin flora]] is allowed to proliferate and cause skin disease. Common examples in dogs include ''[[Staphylococcus|Staphylococcus intermedius]] [[pyoderma]]'', and ''Malassezia dermatitis'' caused by overgrowth of ''[[Malassezia]] pachydermatis''.

[[Alabama rot]], which is believed to be caused by ''[[E. coli]]'' toxins, also causes skin lesions and eventual kidney failure in 25% of cases.{{citation needed|date=November 2019}}

===Flea allergy dermatitis===
{{Main|Flea allergy dermatitis}}

==Hereditary and developmental skin diseases==
Some diseases are inherent abnormalities of skin structure or function. These include [[seborrheic dermatitis]], [[ichthyosis]], [[Ehlers-Danlos syndrome|skin fragility syndrome]] (Ehlers-Danlos), hereditary [[canine follicular dysplasia]] and [[hypotrichosis]], such as [[color dilution alopecia]].

[[Juvenile cellulitis]], also known as puppy strangles, is a skin disease of puppies of unknown [[etiology]], which most likely has a hereditary component related to the immune system.&lt;ref&gt;{{cite journal|last1=Martens|first1=S.M.|title=Juvenile cellulitis in a 7-week-old golden retriever dog.|journal=The Canadian Veterinary Journal|date=February 2016|volume=57|issue=2|pages=202–3|pmid=26834274|pmc=4713003}}&lt;/ref&gt;

[[Lupoid dermatosis]]{{anchor|Lupoid dermatosis}} is a hereditary autosomal recessive disease that has been identified in the [[German Shorthaired Pointer]] and the [[Hungarian Vizsla]]. Clinical signs typically onset before one year of age. Dogs with the condition have a poor life expectancy and are often euthanised after diagnosis.&lt;ref name=&quot;Upenn&quot;&gt;{{cite web |title=Lupoid Dermatosis (Exfoliative Cutaneous Lupus Erythematosus) |url=https://www.vet.upenn.edu/research/academic-departments/clinical-sciences-advanced-medicine/research-labs-centers/penngen/penngen-tests/genetic-tests/Detail/60/ |website=PennGen |publisher=University of Pennsylvania |access-date=27 February 2024}}&lt;/ref&gt; Clinical signs include: [[facial erythema]], crusting and scaling,&lt;ref&gt;{{cite book | last=Rhodes | first=Karen Helton | last2=Werner | first2=Alexander H. | title=Blackwell's Five-Minute Veterinary Consult Clinical Companion | publisher=Wiley-Blackwell | publication-place=Ames, Iowa | date=2011-01-25 | isbn=978-0-8138-1596-1 | page=67}}&lt;/ref&gt; skin lesions, lameness, ulcers, and disfiguration: it progresses to joint pain and azoospermia in males and disruption of the oestrous cycle in females.&lt;ref name=&quot;Upenn&quot;/&gt;

==Cutaneous manifestations of internal diseases==
Some systemic diseases can become symptomatic as a skin disorder. These include many [[endocrine]] (hormonal) abnormalities, such as [[hypothyroidism]], [[Cushing's syndrome (veterinary)|Cushing's syndrome]] (hyperadrenocorticism), and [[tumor]]s of the [[ovaries]] or [[testicles]].

== Nutritional basis of skin disorders ==
=== Essential fatty acids ===
{{Further|Coat (dog)}}
Many canine skin disorders can have a basis in poor nutrition. The supplementation of both omega fatty acids [[Omega-3 fatty acid|3]] and [[Omega-6 fatty acid|6]] have been shown to mediate the inflammatory skin response seen in chronic diseases.&lt;ref name=&quot;:0&quot;&gt;{{Cite journal|last1=Kirby|first1=Naomi A.|last2=Hester|first2=Shaleah L.|last3=Bauer|first3=John E.|title=Dietary fats and the skin and coat of dogs|journal=Journal of the American Veterinary Medical Association|volume=230|issue=11|pages=1641–1644|doi=10.2460/javma.230.11.1641|pmid=17542730|year=2007|doi-access=free}}&lt;/ref&gt; Omega 3 fatty acids are increasingly being used to treat [[pruritic]], irritated skin. A group of dogs supplemented with omega 3 fatty acids (660&amp;nbsp;mg/kg [300&amp;nbsp;mg/lb] of body weight/d) not only improved the condition of their pruritus, but showed an overall improvement in skin condition.&lt;ref name=&quot;:0&quot; /&gt; Furthermore, diets lacking in [[essential fatty acid]]s usually present as matted and unkept fur as the first sign of a deficiency.&lt;ref name=&quot;:0&quot; /&gt; [[Eicosapentaenoic acid]] (EPA), a well known omega 3, works by preventing the synthesis of another omega metabolite known as [[arachidonic acid]].&lt;ref name=&quot;:1&quot;&gt;{{Cite journal|last1=Lee|first1=Je Min|last2=Lee|first2=Hyungjae|last3=Kang|first3=SeokBeom|last4=Park|first4=Woo Jung|date=2016-01-04|title=Fatty Acid Desaturases, Polyunsaturated Fatty Acid Regulation, and Biotechnological Advances|journal=Nutrients|volume=8|issue=1|pages=23|doi=10.3390/nu8010023|pmid=26742061|pmc=4728637|doi-access=free }}&lt;/ref&gt; Arachidonic acid is an omega 6, making it pro-inflammatory. Though not always the case, omega 6 fatty acids promote inflammation of the skin, which in turn reduces overall appearance and health.&lt;ref name=&quot;:1&quot; /&gt; There are skin benefits of both these lipids, as a deficiency in omega 6 leads to a reduced ability to heal and a higher risk of infection, which also diminishes skin health.&lt;ref name=&quot;:0&quot; /&gt; Lipids in general benefit skin health of dogs, as they nourish the [[epidermis]] and retain moisture to prevent dry, flaky skin.&lt;ref&gt;{{Cite journal|last1=Bellows|first1=Jan|last2=Colitz|first2=Carmen M. H.|last3=Daristotle|first3=Leighann|last4=Ingram|first4=Donald K.|last5=Lepine|first5=Allan|last6=Marks|first6=Stanley L.|last7=Sanderson|first7=Sherry Lynn|last8=Tomlinson|first8=Julia|last9=Zhang|first9=Jin|date=2014-12-17|title=Common physical and functional changes associated with aging in dogs|journal=Journal of the American Veterinary Medical Association|volume=246|issue=1|pages=67–75|doi=10.2460/javma.246.1.67|pmid=25517328|issn=0003-1488|doi-access=free}}&lt;/ref&gt;

=== Vitamins ===
Vitamins are one of many of the nutritional factors that change the outward appearance of a dog. The fat soluble vitamins A and E play a critical role in maintaining skin health. [[Vitamin A]], which can also be supplemented as [[Beta-Carotene|beta-carotene]], prevents the deterioration of epithelial tissues associated with chronic skin diseases and aging.&lt;ref&gt;{{Cite journal|last=Watson|first=Tim D. G.|date=1998|title=Diet and Skin Disease in Dogs and Cats|journal=The Journal of Nutrition|volume=128 | issue = 12 |pages=2783–2789 |doi=10.1093/jn/128.12.2783s |pmid=9868266 |doi-access=free}}&lt;/ref&gt; A deficiency in vitamin A can lead to scaly of skin and other dermatitis-related issues like [[alopecia]].&lt;ref&gt;{{Cite journal|author=Baviskar, S|author2=Jayanthy, C|author3=Nagarajan, B|date=2013|title=Vitamin A responsive dermatosis in a dog|journal=Intras Polivet|volume=14 | issue = 2 |pages=210}}&lt;/ref&gt; [[Vitamin E]] is an antioxidant.&lt;ref&gt;{{Cite journal|last1=Debier|first1=C.|last2=Larondelle|first2=Y.|date=February 2005|title=Vitamins A and E: metabolism, roles and transfer to offspring|journal=The British Journal of Nutrition|volume=93|issue=2|pages=153–174|issn=0007-1145|pmid=15788108|doi=10.1079/bjn20041308|doi-access=free}}&lt;/ref&gt; Vitamin E neutralizes [[free radicals]] that accumulate in highly proliferative cells like skin and prevent the deterioration of fibrous tissue caused by these ionized molecules.&lt;ref name=&quot;:2&quot;&gt;{{Cite book|title=Canine and feline nutrition : a resource for companion animal professionals|date=2011|publisher=Mosby|last=Case|first=Linda P.|isbn=9780323066198|edition=3rd|location=Maryland Heights, Mo.|oclc=664112342}}&lt;/ref&gt; There are also a couple of [[water-soluble vitamins]] that contribute to skin health. [[Riboflavin]] (B2) is a cofactor to the metabolism of carbohydrates and when deficient in the diet leads to cracked, brittle skin.&lt;ref name=&quot;:3&quot;&gt;{{Cite book|title=A dictionary of public health|last=Last|first=John M.|date=2007|publisher=Oxford University Press|isbn=9780195160901|location=Oxford|oclc=63176655|url-access=registration|url=https://archive.org/details/dictionaryofpubl0000last}}&lt;/ref&gt; [[Biotin]] (B7) is another B vitamin that, when deficient, leads to alopecia.&lt;ref name=&quot;:3&quot; /&gt;

=== Minerals ===
Minerals have many roles in the body, which include acting as beneficial antioxidants.&lt;ref name=&quot;:2&quot; /&gt; [[Selenium in biology|Selenium]] is an essential nutrient, that should be present in trace amounts in the diet.&lt;ref name=&quot;:2&quot; /&gt; Like other antioxidants, selenium acts as a cofactor to neutralize free radicals.&lt;ref name=&quot;:2&quot; /&gt; Other minerals act as essential cofactors to biological processes relating to skin health. [[Zinc]] plays a crucial role in protein synthesis, which aids in maintaining elasticity of skin. By including zinc in the diet it will not only aid in the development of [[collagen]] and wound healing, but it will also prevent the skin from becoming dry and flaky.&lt;ref&gt;{{Cite journal|last1=Marsh|first1=K.A.|last2=Ruedisueli|first2=F.L.|last3=Coe|first3=S.L.|last4=Watson|first4=T.G.D.|date=2000-12-01|title=Effects of zinc and linoleic acid supplementation on the skin and coat quality of dogs receiving a complete and balanced diet|journal=Veterinary Dermatology|volume=11|issue=4|pages=277–284|doi=10.1046/j.1365-3164.2000.00202.x|issn=1365-3164}}&lt;/ref&gt; [[Copper]] is involved in multiple enzymatic pathways.&lt;ref name=&quot;:4&quot;&gt;{{Cite journal|first1=D.|last1=Tewari|first2=V. K.|last2=Singh|first3=S.|last3=Gautam|first4=V.|last4=Dwivedi|date=2013|title=Nutritional dermatosis - a review|journal=Intras Polivet|volume=14|issue=2|pages=199–202}}&lt;/ref&gt; In dogs, a deficiency in copper results in incomplete [[keratinization]] leading to dry skin and [[hypopigmentation]].&lt;ref name=&quot;:4&quot; /&gt; The complicated combination of trace minerals in the diet are a key component of skin health and a part of a complete and balanced diet.

==References==
{{Reflist}}

==External links==
{{Commons|dog skin disorders}}

{{Dog nav}}

[[Category:Dog diseases|Skin disorders]]