A dog behavior problem: "my dog excessively licks its paw"- Acral Lick Dermatitis (ALD)

As I was visiting one of the dog psychology and behavior forums that are out there, I encountered a post written by a desperate lady. It said:

"my yellow Labrador retriever is constantly licking her paw. It came to the point that she lost her hair, has a lesion and the paw became raw! Yet she keeps licking it. I took her to the veterinarian several times and she has been on different medications but nothing seems to stop it. It starts to get better but she gets right back to lick it. The veterinarian thinks that it is just a nervous habit and that she is doing it out of boredom! I tried buying her all kinds of toys to keep her from getting bored and licking but she busted all the toys within two days and kept licking. I have tried all kinds of sprays and lotions but she still does it. The paw looks just awful! Any ideas?"



Well, the lady's description sounds exactly like a situation known as Acral Lick Dermatitis (ALD) or lick granuloma or canine neuro-dermatitis.

I gathered and summarized some information as well as a reference list for all of you humans that have dogs with such a problem, because I know that it looks very bad and could cause frustration and serious concern for your dog.

What is Acral Lick Dermatitis?

ALD is a condition that develops in dogs as a result of stereotypic, excessive, chronic behavior of licking that result in self-mutilation. Stereotypic behaviors refer to behaviors that are repeated without variation and seem to occur for no apparent purpose. Stereotypic behaviors of excessive grooming, itching and licking are commonly seen in domestic or captive animals. In ALD, the stereotypy is self-licking, chewing or scratching that most commonly occur on the distal portions of the limbs (most common on the front legs of the dog). The constant licking causes areas of hair and skin pigmentation loss, inflammation in the skin, the production of lesions, and over time, the area thickens. The resulting wound is called a Granuloma. The continuous self licking and chewing prevents the lesion from healing and may cause discomfort, pain and, in severe cases, crippling. The lick Granuloma often becomes infected with bacteria (mostly a bacteria called Staphylococci), causing a secondary problem. It is likely that the licking and the inflammation creates a vicious cycle in which the erosion of the skin leads to pain and itch, which causes more licking.


Acral Lick Dermatitis (ALD)- a picture of a lesion. Taken from Wikipedia (2009).

Are there any breeds of dogs that are more at risk for Acral Lick Dermatitis?

Essentially, any dog can develop ALD, yet middle-aged, large and active breed of dogs are more prone to this condition. These breeds include:
The Doberman Pinscher, German Shepherd, Great Dane, Golden Retriever, Labrador Retriever, Irish Setter, Boxer, Border Collie, Dalmatian, Shar- Pei and Weimaraner. Males of these breeds are more prone to the condition than females.


The German Shepherd (the upper picture) and the Labrador Retriever (its three main colors). Two breeds of dogs that are prone to ALD. Taken from Wikipedia (2009).

What causes Acral lick dermatitis?

The exact causes of ALD are unknown. This condition could have several factors involved- some of them work in combination, adding to the complexity of the problem. In some breeds, notably Doberman Pinschers and Great Danes, the cause might not be found.

Some possible physical underlying causes of the licking behavior include: Allergic Dermatitis (skin allergies), Ecto- parasites (External parasites such as Scabies, Demodex or skin mites),
fungal Infections (such as Blasto-mycoses and Ringworm), Neuro-Pathies (inflammation of the nerves under the skin), Neo-Plasia (skin cancer that can cause chronic lesions), hypothyroidism (especially in black Labrador Retrievers), and Arthritis (joints disease or inflammation of the covering bone). These conditions could cause the dog to lick the area, which leads to more pain and itching, which lead to more licking.

Nevertheless, one of the most common causes of lick Granulomas is considered Psychogenic which is a general term for psychological causes that are thought to be involved. The Psychogenic causes of lick Granulomas include boredom, stress, loneliness, and separation anxiety. A situation in which the dog stays many hours home alone on a regular basis could contribute or even lead to the development of ALD.

ALD is actually considered a form of canine obsessive-compulsive disorder, similar to obsessive-compulsive disorders in humans. According to one theory, the excessive licking leads to the secretion of Endorphins (chemical substances which provide a sense of well-being) in the dog's brain or acts as a release of tension mechanism in bored, socially isolated dogs, or dogs that are left alone for many hours a day. The dog soon learns that licking brings a pleasant feeling, and keeps on licking. Other mentioned causes for the self-licking may also be an over- attentive or nervous owner who inadvertently fosters nervous behaviors in the dog, the introduction of new animals or people into the household, as well as other profound changes in the dog's environment.
It is often very difficult to determine if the excessive licking is caused by physical or psychological factors yet an accurate diagnosis it is very important for effective treatment.

How is Acral Lick Dermatitis diagnosed?

In order to ensure an accurate diagnosis, a thorough approach is required. The diagnosis process could include:

A. A veterinarian collecting the history of the dog with special attention on the dog's age (ALD usually starts appearing when the dog reaches at least 5 years of age) and the time of the potential ALD appearance (when it first appears it might coincide with allergy symptoms that are seasonal in nature).
B. A thorough physical exam of the dog and the lesion by a veterinarian.
C. Diagnostic Tests- are important because many skin conditions look the same, even though they have different causes and are treated differently. In some situations other skin diseases can occur simultaneously with ALD. The tests could include skin scraping to test for Ecto-parasites, a fungal culture, radiography (an x- ray to test for joint problems), a skin biopsy that helps differentiate skin tumors or deep fungal infections, a fine needle aspiration (an alternative to an actual skin biopsy in which the veterinarian uses a syringe with a tiny needle to take a sample of the affected area which is later put on a microscope slide for analysis by a pathologist), a bacterial culture to identify the type of bacteria involved, Thyroid functioning levels test, and allergy tests which could also be performed by having the dog on a hypoallergenic diet for two months, to rule out allergies. Basically, psychogenic ALD is diagnosed when all of these tests come out negative.

What is the treatment for Acral Lick Dermatitis?

ALD is a significantly frustrating and relatively difficult condition to treat, with control being achieved in reportedly 65 percent of the cases. If the licking behavior already became chronic and the behavior continues for years, few treatments are considered successful. That is why it is extremely important to treat the condition as soon as it appears: catch lesions early as they appear and keep the dog from licking them to reduce inflammation and prevent the development of a habit. Regardless of achieving full control of the condition, with proper treatment the dog will probably feel more comfortable.

Many methods of ALD treatments are available, which is an indication of the complexity of this disease. None of the treatments were shown to be consistently effective and some of them work in tandem. Treatment of the primary cause of the condition is essential, based on the diagnosed causes. Each of the treatments has varying degrees of success on a case by case basis and that is why it is very important to be patient with the dog and treatments, keep trying and consider it a process of trial and error.

Any treatment should include a treatment for the healing of the lesion. These could include:

Flea control- The products available today offer a significant improvement in flea control than the products in the recent past. They are economical, safe, effective, and very convenient.

Anti- inflammatory treatment- Cortisone is used initially to minimize swelling and licking. It is not used as the primary means to control ALD in the long term since a skin infection is almost always present and cortisone decreases the immune system's ability to fight this infection. Cortisone is used much more often in treating allergic dermatitis. Methylprednisolone acetate, which is a long acting corticosteroid hormone (Glucocorticoid), is sometimes used in combination with antibiotics.

Anti-arthritic drugs- in case of ALD that originates in Arthritis, anti Arthritic drugs such as Etogesic (Etodolac) or Rimadyl (Carprofen) are used.

Topical medications- If used in combination with long term oral antibiotics, topical medication such as corticosteroids can be beneficial. They are not effective when used alone.

Antibiotics- Since bacterial infection is almost always present in this condition, oral antibiotics is probably the most important treatment for the lesions in ALD. In some cases, the antibiotics are used for 4-6 months due to the condition's chronic nature. It is important to continue administrating the antibiotics for at least 3 weeks after the skin looks healed. Some dogs are put on intermittent antibiotic therapy for the rest of their lives- this is called "pulse therapy". Antibiotics that work best include: Cephalexin, Primor, Baytril, Clavamox.

Laser therapy- It could take at least 3 laser treatments to see an improvement, and in some cases the laser can significantly help in minimizing the licking.
Anti-fungal medication- If a deep seated fungal infection is diagnosed the dog will be treated using oral fungal medication for an extended period.

Anti- allergy shots- This can be a good way to minimize itching without using Cortisone. The less we use Cortisone to minimize itching, the faster the problem will resolve. These are injections given to the dog on a long term basis, usually once a month, once the allergy is improving.

Food allergy treatment- Feeding the dog with a hypoallergenic diet.
Food Supplements-Some allergic dogs and cats scratch less when supplemented with essential fatty acids.

Excision surgery- Surgery may be performed to remove whole lesions, but there is high risk of continued self mutilation to the area later on.
Thyroid medication- if hypothyroidism is involved.

Elizabethan collars and other restrictive collars- Are used to physically prevent licking. One good suggestion that is tolerated well by larger dogs is a small plastic bucket with a hole cut out of the bottom that is placed over the head. Bandaging is also used to allow the lesion to heal. Anti- licking bitter sprays and ointments are almost never effective in preventing the licking behavior.


The Elizabethan collar on a dog. Taken from Wikipedia (2009).

It is important to note that many dogs will lick at another leg, creating a new lick granuloma, if they are prevented from licking the original one while it heals.

Radiation therapy and acupuncture are additional forms of treatments.

Behavior modification- None of the above treatments address the behavioral origins of the disorder yet treating the psychological factors of the condition is most important in treating ALD. Without behavior modification treatment, the treatments mentioned above may have short term success, but after the collar or bandage is removed or the medication stopped, the self-mutilation behavior almost always resumes. That is why treatment must begin with behavioral modification that is later combined with one of the above treatments, according to the advice of the veterinarian.

The behavior treatment should begin with the owner trying to identify the stimuli which are causing the dog's obsessive-compulsive behavior or anxiety. The owner should observe the environment and consider the lifestyle of the dog.

The owner should ask questions such as:

Is the dog socially isolated with little or no human contact?

Is the dog crated for long hours at a time?

Is the dog home alone for 8 or more hours a day?

What kind of exercise does the dog receive and how much exercise?

Hereby are several suggestions which may help humans prevent an onset of ALD and aid in its behavioral treatment:

• Ensure that your dog gets sufficient exercise. By exercise I mean not just being in a yard, but also leashed walks where the owner is interacting with the dog. At least three walks a day are recommended, if possible. You can also place a special dog backpack on the dog's back during walks, so that the dog will get the feeling that she/he are working. Remember that ALD appears mainly in large active breeds of dogs!

• Take your dog to obedience classes or participate in dog sports such as agility or fly- ball. The suggested sports activities can challenge the dog as well as provide the dog with exercise and time to interact with other dogs. If you cannot avoid leaving the dog alone for 7-8 hours a day, consider coming home at lunch, or having someone take the dog out for you. Another option is to get a second dog or cat for company. In general, try to increase the interaction with your dog and avoid confinement.
  

• It is very important to choose a breed of dog which is suitable for your lifestyle. If you are sedentary and enjoy relaxing on your days off, you should not own a large active breed that won't be able to get enough activity for its levels of energy. Consider smaller toy breeds or even a cat instead.

All of the above suggestions are intended to improve the human-dog bond as well as decrease the stress and anxiety which may lead to such behavioral disorders such as canine ALD.

Some psychiatric medications may be used until the behavior modification has begun to take effect. Antidepressants and antiobsessional medications are most commonly used, including Doxepin, Amitriptyline, Fluoxetine, and Clomipramine. As mentioned above, one of the theories for the licking behavior in ALD is that the licking releases brain chemicals (Endorphins), which cause the dog to "feel good". This causes the licking cycle to continue. An option to reduce the addiction to licking is to provide Endorphin blockers such as Naltrexone or Endorphin substitutes such as Hydrocodone that may decrease the urge to lick. Another suggestion that I found was to provide a lot more "feel good" activities for the dog since boredom seems to be one of the major causes of ALD.

What is the general prognosis (the expected outcome) for the dog?

This condition is usually more of an unsightly imperfection in the eyes of humans rather than a life threatening condition. Nevertheless, if the condition becomes a well established habit for the dog, the truth is that it is rarely completely cured. That is why early and accurate diagnosis (as soon as the behavior is apparent) is the best scenario, which leads to the administration of proper medication and behavior treatment before the problem becomes so chronic that treatment is only marginally effective.

To all the humans that have dogs that suffer from this condition: remember again, be patient with your dog and try different methods of treatment. Consider this a trial and error process. Remember that the key for improving the dog's condition is behavioral treatment and establishing a better relationship with your dog! After all, you chose to have a dog as a companion, so please spend time with him/her!

If you have any other questions about this condition, I will be happy to answer.

Till next time, woof woof

Sushoni

References and further readings

1. Ackerman, L. (1994). Guide to skin and haircoat problems in dogs (pp. 129-130). Loveland, CO: Alpine Publications.
2. Ackerman, L. (2005). What's New in Veterinary Dermatology. Proceedings of the world congress of the World Small Animal Veterinary Association, Mexico, 30. Retrieved June 3, 2007, from http://www.vin.com/proceedings/Proceedings.plx?CID=WSAVA2005&PID=10980&O=Generic.
3. Davis, L. E. (Ed.) (1985) Handbook of Small Animal Therapeutics. Toronto: Academic Press Canada.
4. Dodman, N. E., Shuster, L.E., White, S.E., Court, M.E., Parker, D., & Dixon, R. (1988). Use of narcotic antagonists to modify stereotypic self-licking, self-chewing, and scratching behavior in dogs. Journal of the American Veterinary Medical Association, 193(7), 815-819.
5. Goldberger, E. G. & Rapoport, J.L. (1991). Canine Acral Lick Dermatitis: Response to the antiobsessional drug Clomipramine. Journal of the American Animal Hospital Association, 27, 179-182.
6. Hines, R. (n.d.) Why is my dog licking its elbows and legs? Acral lick Dermatitis or Granuloma. Retrieved July 19, 2009, from http://www.2ndchance.info/acral.htm
7. Long Beach Animal Hospital (n.d.). Acral Lick Dermatitis. Retrieved July 19, 2009, from http://www.lbah.com/canine/ald.htm
8. Luescher A. (2000). Compulsive Behavior in Companion Animals.
Recent Advances in Companion Animal Behavior Problems. Retrieved June 3, 2007, from http://www.ivis.org/advances/Behavior_Houpt/luescher/ivis.pdf.
9. Paterson, S. (1998). Skin diseases of the dog (pp. 239-241). London: Blackwell Science Ltd.
10. Rivers, B., Walter, P.A., & McKeever, P.J. (1993). Treatment of Canine Acral Lick Dermatitis with Radiation Therapy: 17 cases. Journal of the American Animal Hospital Association, 29, 541-544.
11. Scott, D.W., Miller, W.H., & Grifin, C.E. (2000). Muller & Kirk's small animal dermatology (6th ed., pp. 1058-1064). Philadelphia, PA: W.B. Saunders Co.
12. Stein D., Mendelsohn I., Potocnik F., Van Kradenberg J., & Wessels C. (1998). Use of the selective serotonin reuptake inhibitor Citalopram in a possible animal analogue of obsessive-compulsive disorder. Depress Anxiety 8 (1), 39–42.
13. Stookey, J., Watts, J.,& Haley, D. (2009). Acral Lick Dermatitis (ALD). Retrieved July 19, 2009, from the University of Saskatchewan, Applied Ethology Website: http://www.usask.ca/wcvm/herdmed/applied-ethology/behaviourproblems/lickderm.html
14. White, S. J. (1990). Naltrexone for treatment of Acral Lick Dermatitis in dogs. Journal of the American Veterinary Medical Association,196(7), 1073-1076.
15. Wikipedia (2009). Lick Granuloma. Retrieved July 19, 2009, from http://en.wikipedia.org/wiki/Lick_granuloma