Title: Lick granuloma

{{Infobox medical condition (new)
| name            = Lick granuloma
| synonyms        = Acral lick dermatitis
| image           = Canine lick granuloma.jpg
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| caption         = Canine lick granuloma is a self-inflicted [[lesion]] often complicated by [[secondary infection]]
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| field           = [[Veterinary medicine]]
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A '''lick granuloma''', also known as '''acral lick dermatitis''', is a [[skin disorder]] found most commonly in [[dog]]s, but also in cats. In dogs, it results typically from the dog's urge to lick the lower portion of one of their legs.

The [[lesion]] can initially be red, swollen, irritated, and bleeding, similar to a [[Pyotraumatic dermatitis|hot spot]] (wet eczema).  The animal's incessant licking of the lesion eventually results in a thickened, firm, oval [[Plaque (dermatology)|plaque]], which is the granuloma.

A major cause of lick granuloma appears to be psychological, related to stress, anxiety, [[Separation anxiety in dogs|separation anxiety]], boredom, or compulsiveness.  Lick granulomas are especially seen in active dogs left alone for long periods of time.  

One theory about the cause of lick granulomas is that excessive licking causes [[endorphin]] release, which reduces pain and makes the animal feel comfort temporarily.&lt;ref&gt;{{Cite web|title=Acral lick granuloma: stopping the itch-lick cycle|url=https://www.dvm360.com/view/acral-lick-granuloma-stopping-itch-lick-cycle|access-date=2021-05-11|website=DVM 360|date=22 August 2019 }}&lt;/ref&gt; 

Other triggers include itchy skin, painful conditions caused by trauma to the skin, arthritis, neuralgia, and peripheral neuropathy. A bacterial or fungal infection of the skin can also trigger itching, as can skin mites, allergies, a reaction to an environmental irritant or toxin, hyperthyroidism, and certain types of cancer.

Treatment of the primary cause, if known, is essential.  In [[Psychogenic disease|psychogenic]] cases, psychological factors should be identified and addressed, such as being left alone all day, being confined, and changes in the household.

==Signs and symptoms==

Lick granuloma is a form of self-trauma and [[skin disorder]] in which most commonly dogs, but also cats, continuously lick a small area of their body until it becomes raw and inflamed. The most common areas affected are the lower ([[Anatomical terms of location#Proximal and distal|distal]]) portions of their legs, such as the [[Carpal bones|carpus]] (wrist),&lt;ref&gt;{{cite book|url=https://books.google.com/books?id=FbH5hP00V20C&amp;dq=%22Lick+granuloma%22&amp;pg=PA99 |title=The Dog's Drugstore: A Dog Owner's Guide to Nonprescription Drugs and Their ... |author1=Richard W. Redding |author2=Myrna Papurt |date=15 August 2001 |publisher=Macmillan |isbn=9780312978891 |accessdate=December 29, 2012}}&lt;/ref&gt; or sometimes another part of their body such as the base of their tail.

Seventy percent of the time it occurs on one of the dog's left legs.&lt;ref name=&quot;Beaver2009&quot;&gt;{{cite book|last=Beaver|first=Bonnie V. G.|title=Canine Behavior: Insights and Answers|url=https://books.google.com/books?id=S6o5ypyRPQEC&amp;pg=PA289|year=2009|publisher=Elsevier Health Sciences|isbn=978-1-4160-5419-1|page=289}}&lt;/ref&gt;  

The [[lesion]] can initially be red, shiny, swollen, hairless, irritated, and bleeding, similar to a [[Hot spot (veterinary medicine)|hot spot]] (wet eczema).&lt;ref name=&quot;Google2&quot;&gt;{{cite book|author1=Debra M. Eldredge, DVM|author2=Liisa D. Carlson, DVM|author3=Delbert G. Carlson, DVM|author4=James M. Giffin, MD|title=Dog Owner's Home Veterinary Handbook|url=https://books.google.com/books?id=pXubvmBSz4gC&amp;pg=PA134|year=2010|publisher=John Wiley &amp; Sons|isbn=978-0-470-89328-9|page=134}}&lt;/ref&gt;&lt;ref name=&quot;google3&quot;&gt;{{cite book|author1=James G. Fox|author2=Lynn C. Anderson|author3=Franklin M. Loew|author4=Fred W. Quimby|title=Laboratory Animal Medicine|url=https://books.google.com/books?id=m2ftfPMJnMMC&amp;pg=PA434|date=20 June 2002|publisher=Academic Press|isbn=978-0-08-053533-3|page=434}}&lt;/ref&gt; Eventually, a raised hard plaque forms.&lt;ref name=&quot;MullerKirk2001&quot;&gt;{{cite book|author1=George H. Muller|author2=Robert Warren Kirk|author3=William Howard Miller|author4=Craig E. Griffin|title=Muller &amp; Kirk's Small Animal Dermatology|url=https://books.google.com/books?id=aK2XZdCiwdwC&amp;pg=PA1058|year=2001|publisher=Saunders|isbn=978-0-7216-7618-0|pages=1058–}}&lt;/ref&gt;

Frequent formations of lick granulomas in the same area due to the constant licking will cause hardening, callous formation, hair loss (the hair may stop growing back), and [[hyperpigmentation]] to that area.{{cn|date=April 2024}}

Lick granulomas sometimes become infected with [[bacteria]], causing [[Abscess|abscessed]] areas or fistulous tracts ([[furuncles]]).{{cn|date=April 2024}}

==Causes==

Lick granulomas are caused by a variety of factors. One common cause of lick granulomas appears to be psychological, related to stress, anxiety, [[Separation anxiety in dogs|separation anxiety]],&lt;ref name=&quot;google1&quot;&gt;{{cite book|url=https://books.google.com/books?id=aK2XZdCiwdwC&amp;dq=%22Lick+granuloma%22+%22alone%22&amp;pg=PA1058 |title=Muller &amp; Kirk's Small Animal Dermatology |author1=George H. Muller |author2=Danny W. Scott |author3=Robert Warren Kirk |author4=William H Miller Jr |author5=Craig E. Griffin |year=2001 |publisher=W.B. Saunders |isbn=9780721676180 |accessdate=December 29, 2012}}&lt;/ref&gt; boredom, or compulsiveness.&lt;ref name=&quot;triblive1&quot;&gt;{{cite news|url=https://triblive.com/x/pittsburghtrib/lifestyles/family/dogtalk/s_40912.html#axzz2GQ2FsftX |title=Curbing dog's anxiety may lick the medical problem |publisher=TribLIVE |date=March 4, 2001 |accessdate=December 29, 2012}}&lt;/ref&gt;  Lick granulomas are especially seen in large active dogs left alone for long periods of time.&lt;ref name=&quot;triblive1&quot;/&gt;&lt;ref&gt;{{cite news|url=https://news.google.com/newspapers?id=0xYzAAAAIBAJ&amp;sjid=XTIHAAAAIBAJ&amp;pg=5803,5348873&amp;dq=lick-granuloma+alone&amp;hl=en |title=Lodi News-Sentinel |accessdate=December 29, 2012}}&lt;/ref&gt;  It is often considered to be a form of canine [[obsessive-compulsive disorder]].&lt;ref&gt;{{cite journal |vauthors=Stein D, Mendelsohn I, Potocnik F, Van Kradenberg J, Wessels C |title=Use of the selective serotonin reuptake inhibitor citalopram in a possible animal analogue of obsessive-compulsive disorder |journal=Depress Anxiety |volume=8 |issue=1 |pages=39–42 |year=1998 |pmid=9750979 |doi=10.1002/(SICI)1520-6394(1998)8:1&lt;39::AID-DA8&gt;3.0.CO;2-0|doi-access=free }}&lt;/ref&gt;&lt;ref name=&quot;google1&quot;/&gt;

Other causes include [[bacteria]]l or [[fungus|fungal]] infections, [[Parasitism|ectoparasites]], [[Metabolic disorder|metabolic]] disease, [[Neoplasm|neoplastic]] disease, trauma causing nerve damage, allergies, or joint disease.  [[Hot spot (veterinary medicine)|Hot spots]] may also lead to the formation of lick granulomas.

Arthritic and mobility problems in older dogs give them more time to lick and over-groom themselves.&lt;ref&gt;{{cite web|author=Luescher A. |year=2000 |title=Compulsive Behavior in Companion Animals |work=Recent Advances in Companion Animal Behavior Problems |url=http://www.ivis.org/advances/Behavior_Houpt/luescher/ivis.pdf |accessdate=March 6, 2007 |url-status=dead |archive-url=https://web.archive.org/web/20070927031737/http://www.ivis.org/advances/Behavior_Houpt/luescher/ivis.pdf |archive-date=September 27, 2007 }}&lt;/ref&gt;

The condition becomes a vicious cycle&amp;nbsp;– erosion of the skin from licking leads to pain and itching, which leads to more licking.

==Treatment==

===Of primary cause===
Treatment of the primary cause, if known, is essential.

In [[Psychogenic disease|psychogenic]] cases, dealing with psychological factors is most important.  Factors should be identified such as being left alone all day, being confined, and changes in the household. Correction of these causes may include increased walks, avoiding confinement, and more interaction in the home.  Some veterinarians have  proposed that diet can affect [[compulsive behavior]]s in dogs.&lt;ref&gt;{{cite web|url=http://www.2ndchance.info/homemadediets.htm#S2 |title=Home Cooked Pet Diets, Home Made Recipes and Pet Nutrition |publisher=2ndchance.info |accessdate=December 29, 2012}}&lt;/ref&gt;

Drugs may be used until [[behavior modification]] has had time to take effect.  [[Antidepressant]]s are most commonly used, including [[doxepin]], [[amitriptyline]], [[fluoxetine]], and [[clomipramine]].  If the psychological factors are not corrected, the pet will usually relapse after the drugs are discontinued.  [[Opioid antagonist|Endorphin blocker]]s such as [[naltrexone]] can be used to reduce addiction to licking, or endorphin substitutes such as [[hydrocodone]] may decrease the urge to lick.&lt;ref name=Griffin_2001/&gt;

The animal should be tested for allergies, and treated accordingly if positive ([[fatty acid]]s, [[antihistamine]]s, hypoallergic diet, etc.).  It may also be necessary to check [[thyroid]] levels, as [[Hypothyroidism in dogs|hypothyroidism]] seems to play a role in some cases, particularly in black Labrador retrievers; thyroid medication often will resolve the problem if it is due to hypothyroidism.&lt;ref&gt;{{cite web|url=http://www.thepetcenter.com/exa/lick.html |title=Lick Granuloma Skin Lesions, Treatments and Management In Dogs at |publisher=Thepetcenter.com |accessdate=December 29, 2012 |url-status=dead |archive-url=https://web.archive.org/web/20110531092608/http://www.thepetcenter.com/exa/lick.html |archive-date=May 31, 2011 }}&lt;/ref&gt;

===Of lesion===

The lesion should also be treated.

Class 4 infrared laser treatments have been used with much success, although it may take several treatments to achieve the desired outcome.

Licking can be prevented by the use of [[Elizabethan collar]]s, dog leggings, battery-enhanced wraps, bandages, anti-licking ointments (which are bad tasting), and anti-lick strips (which are either bad tasting or simply provide a barrier).  It is important to catch lesions early and keep the animal from licking them to then reduce inflammation and development of a habit. [[Topical medication]]s such as [[corticosteroid]]s or [[dimethyl sulfoxide|DMSO]] may be effective if used early.

Small lesions may be injected with [[triamcinolone]] or [[methylprednisolone]].  Oral [[antibiotic]]s are used to control infection.  Surgery may be performed to remove whole lesions, but there is risk of continued self-mutilation to the area afterwards.  Other potential treatments include [[cryosurgery]], [[Soft tissue laser surgery|laser surgery]], [[radiation therapy]], and [[acupuncture]].  It is important to note that many dogs will lick at another leg, another area on the same leg, or someplace else, creating a new lick granuloma, if they are prevented from licking at the original one while it heals.

===Success rate===

Overall, lick granulomas are very difficult to treat, with control only being achieved in about 65 percent of cases.&lt;ref&gt;{{cite web | last = Ackerman | first = Lowell | title = What's New in Veterinary Dermatology | work = Proceedings of the 30th World Congress of the World Small Animal Veterinary Association | year = 2005 | url = http://www.vin.com/proceedings/Proceedings.plx?CID=WSAVA2005&amp;PID=10980&amp;O=Generic | accessdate = March 6, 2007 }}&lt;/ref&gt;  Some animals will continue to lick at the area despite the use of anti-lick ointments or sprays to deter them, for instance.

==Commonly affected dog breeds==

Many large breed dogs appear to be predisposed, as well as [[golden retrievers]]&lt;ref&gt;{{cite book|url=https://books.google.com/books?id=dVjluhyc7sUC&amp;dq=%22Lick+granuloma%22+%22alone%22&amp;pg=PA130 |title=Captain Doctor Dave's Wilderness Veterinary Companion for Cruisers and ... |author=David LaVigne |date=March 2006 |publisher=Lulu.com |isbn=9781411669758 |accessdate=December 29, 2012}}&lt;/ref&gt; and other [[bird dog]]s.&lt;ref name=&quot;triblive1&quot;/&gt; Most of the dogs with the condition are over five years of age.&lt;ref name=&quot;google1&quot;/&gt;  
{{Div col|colwidth=22em}}
*[[Airedale Terrier]]
*[[Boxer (dog)|Boxer]] 
*[[Doberman]]
*[[Golden Retriever]]
*[[Great Dane]]
*[[Irish Setter]]
*[[Labrador Retriever]] 
*[[Weimaraner]]
 {{div col end}}
&lt;ref name=&quot;Dodds, 1994(2011)&quot;&gt;{{cite web | last = Dodds | first = W. Jean | title = Guide to Congenital and heritable Disorders in Dogs: Includes Genetic Predispositions to Diseases | year = 2011|orig-year= 1994| url = https://www.hsvma.org/assets/pdfs/guide-to-congenital-and-heritable-disorders.pdf | accessdate = March 6, 2020 }}&lt;/ref&gt;
&lt;ref name=&quot;Griffin_2001&quot;&gt;{{cite book|last=Griffin|first=Craig E.|author2=Miller, William H. |author3=Scott, Danny W. |year=2001|title=Small Animal Dermatology|edition=6th|publisher=W.B. Saunders Company|isbn=0-7216-7618-9}}&lt;/ref&gt;
&lt;ref&gt;{{cite journal | last = Ogata | first = N. | title = Canine Compulsive Disorder | journal = Proceedings of the 40th World Congress of the World Small Animal Veterinary Association | year = 2015 | url = https://www.vin.com/apputil/content/defaultadv1.aspx?id=7259303&amp;pid=14365 | accessdate = March 6, 2020 }}&lt;/ref&gt;
&lt;ref&gt;{{cite journal | last = Rosychuk | first = Rod A.W. | title = Canine Lick Granuloma | journal = Proceedings of the 36th World Congress of the World Small Animal Veterinary Association | year = 2011 | url = https://www.vin.com/apputil/content/defaultadv1.aspx?pId=11343&amp;meta=generic&amp;catId=34572&amp;id=5124321&amp;ind=180&amp;objTypeID=17 | accessdate = March 6, 2020 }}&lt;/ref&gt;

==References==
{{Reflist}}

== External links ==
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[[Category:Dog diseases]]
[[Category:Cutaneous conditions]]
[[Category:Anxiety disorders]]
[[Category:Self-harm]]