(and sometimes cats) lick themselves
raw for a number of reasons. Sometimes it is very hard for veterinarians
to determine what those reasons are. Most often, it is a combination
of factors - some physical, some psychological - that entwine and
lead to the problem. In every case, your dog's unique temperament
has to be considered. No one treatment will cure all dogs and often
a number of approaches need to be used simultaneously to cure your
pet. Some pets can not be completely cured of this problem - but
all can be made better. You will need patience and persistence to
get your pet through this problem. It is not something your veterinarian
can do for you.
What is Acral lick dermatitis ?
Acral lick dermatitis or lick granuloma is a sore that does not heal and that usually occurs on pet's lower leg. It looks somewhat similar to the bed sores that occur in debilitated people due to poor circulation and pressure; but in dogs, the cause is their continuous licking of a small area. It most commonly affects the lower leg, in an area the dog can comfortably reach while laying on its stomach or side. It can occur in high-strung, obsessive, anxious or stressed pets of any age, but veterinarians also see it in older (5-6+ years or so) large dogs that, for a number of reasons, have begun to slow down and move about less.
Vets see it most commonly in Doberman pinchers, labrador retrievers, golden retrievers, their crosses and other large active breeds. In those dogs, the pet's individual genetics contributes to the problem. (ref) An underlying medical or health problem is usually not identified but ,occasionally, such problems due underlie the condition. You can read about those rarer cases here.
Lick-related skin problems (which include acral lesions) account for a substantial percentage of veterinary hospital visits. In Montreal, skin problems accounted for a fifth of all veterinary teaching hospital visits. In the Southern US where I practice, and where fleas and allergies are worse, I believe that percentage is considerably greater. You can read more about those veterinary visits here.
Acral lesions usually occur where bone and skin are in close proximity (close together). When the affected area is over heavy muscle and fat, abdominal or chest wall it almost certainly rate a biopsy to rule out any underlying tumor or infection. The same goes for lesions in areas that are difficult for pets to easily lick and groom.
More About The Problem :
Acral lesions are a fairly common problem in older, sedentary dogs. Many of them are overweight as well. Some are found to be hypothyroid. As pets age and arthritis and obesity make them less mobile, pets spend more and more time grooming themselves and worrying small areas of their skin – activities that requires less energy and can be performed in a resting position. If your pet is older and you suspect that its limited mobility is adding to the licking problem (or the cause of it) , you can read about arthritis treatment in dogs here and some of the special needs of older dogs here.
Sometimes the lesion begins as a scrape or pustule; but often there is no apparent defect at the site where licking begins. It is very uncommon for a dog to have more than one or two of these areas on his or her body. As they continuously lick these areas, hair is lost, the area becomes firm and raised and superficial staphylococcal infections often set in (furunculosis) . With time the skin of the area thickens and either gains or looses pigment. The resulting wound is called a granuloma. The center of these lesions is often ulcerated. These wounds are often unsightly but never life-threatening. They do not appear to be very painful to the pets either. Scabs rarely form because of their incessant licking.
What Causes This Problem ?
That is really not a valid question because acral granulomas are the end result of a number of problems with varied causes, not a disease in itself. Those causes are known to include trauma (injuries), itching, peripheral nerve irritation, boredom, allergies, skin infections, arthritis and other joint problems or a new stress such as an additional family member or pet. But I believe that boredom, confinement, loneliness, separation anxiety and decreased ability to move about and interact with their environment are the root causes of most cases I see in pets. You can read about other self-destructive behaviors that separation anxiety causes here. It is often very difficult to determine whether physical or psychological problem are more important in causing the pet’s obsessive licking and grooming of the area(s). You can read another article on health problems that may be rooted in compulsiveness here. (even diet can affect your dog's mood and activities, you might experiment with some of the dietary changes you find here)
If you have recognized other obsessive compulsive behaviors in your pet over the years, that might be an indication that the pet is now using licking to relieve inner stress.
If you have noticed allergic problems in your pet over the years, explore the possibility that acral lesions have become a new part of that problem. But do not confuse the interdigital (between the toes) pus pockets and infections (interdigital cysts, interdigital pyoderma) with acral lesions. Those lesions are due to the dampness of constant paw-licking and its breakdown of the outer protective layer of the skin. For that problem, you need to read this article as well.
How Is Acral Lick Dermatitis Diagnosed ?
Veterinarians diagnose acral lick granuloma through a careful examination of the lesion, the pet’s history, age and a thorough physical exam. Occasionally I will send a skin biopsy to a pathologist to rule out cancer or primary infection. I may x-ray the area to be sure no bone spurs, arthritis or periostitis (inflammation of the covering of the bone) are the cause. I may try the pet on a hypoallergenic diet for sixty days to rule out allergies. Occasionally I will run a bacterial culture of the area. But most of the bacteria that are cultured from these areas are just opportunistic contaminants.
Acral lick granuloma is the diagnosis when all these tests come back negative.
What Are The Treatments Veterinarians Have To Offer ?
My most effective way to eliminate this problem is either to convince owners to use a muzzle on their pets (when they are not available to interact and supervise them) or to bandage the area with a light dressing during those periods. Bitters sprays and ointments almost never work. Veterinarians are most successful when they begin treating these lesions early. After years of licking, few treatments are successful at truly eliminating these pet's urge to lick the area. Some times I will even place small ringlets of stainless steel wire (like a body pierce) in the area (with the sharp ends up) that discourage licking. Other times I temporarily tranquilize these dogs with acepromazine to discourage licking until I can come up with a long-term behavioral modification or chemotherapeutic (medicine-based) plan that might solve the problem.
Elizabethan (restrictive) collars sometimes cure the condition, but it often reoccurs when the collars are removed. Encouraging exercise through weight reduction or a second, younger, pet sometimes cures the problem. If I think the problem is primarily psychological (obsessive/compulsive behavior), I often place these dogs on chlomipramine hydrochloride, an anti-obsessional drug that belongs to the dibenzazepine class of tricyclic antidepressants. You can read about the use of this group (SSRIs) of medications to treat acral lick granulomas here.
Medications that are sometimes used to treat addictions in humans are also occasionally helpful. You can read about the use of one of them, naltrexone, here. Some veterinarians also occasionally find phenobarbital helpful. I do not, but just like dogs that receive that medication for epilepsy, their blood chemistries needs to be carefully monitored.
Frequent, small feedings can be used to help relieve boredom.
If I think arthritis may be an underlying problem, I put the dogs on anti-arthritic drugs such as Etogesic (etodolac) or Rimadyl (carprofen) for a trial period. If a significant bacterial secondary infection exists, I place the dog on a good antibiotic to get the infection under control. Sometimes, antibiotic-containing ear preparations (such as Tresaderm or Panalog) massaged into the areas are sufficient to do that. If these lesions are surgically removed, they often reoccur in the same area. If the dog is overweight, I encourage the owner to feed it a lower calorie diet - particularly one made at home. (ref)
No mater what I believe the cause might be, I often put these pets in a restrictive collar, muzzle or bandage to give the lesion a chance to heal. I prefer that my clients just use a well-fitting muzzle if they will agree to it. After a few days, your dog will not object to it, if it fits well. You can see a well-fitted muzzle here. Pets only need to wear these devices when owners are unable to supervise them. (Dogs quickly learn that you do not want them worrying the area and a concerned glance or word is usually all it takes to make them stop)
There is one theory that licking these lesions releases “feel good” endorphins (brain chemicals), which cause the cycle to continue. I do not know of any medication that would break such a cycle without causing other , more objectionable, side effects. Your pet would be better off if you found other natural non-destructive ways for it to produce those "feel good" chemicals.
No matter what the underlying cause of licking or itching is in your pet, boredom, inactivity and unoccupied time will make it worse. It is not unusual for the underlying cause of itching to be eliminated by your veterinarian only to have the pet continue to scratch and lick itself from force of habit. To minimize this, give your pets plenty of distractions. Hidden food morsels, toys and chew toys, walks, play time, other pets, and view through a porch, kennel or window all take your pet's mind off of its skin. You can see a style of hidden food morsel contraption I like here. Try these distractions, and others you might think of, before you resort to tranquilizers and mood-altering medications. You might get other ideas from an article on animal enrichments that you can read here - or invent your own.
What About Just Having My Veterinarian Surgically Remove The Affected Area ?
I strongly discourage you from suggesting or agreeing to that. I have never seen a case where surgically removing the diseased tissue cured the pet. It will almost certainly begin to lick and chew at that, or another area again. Surgery can also result in the need for much more extensive reconstructive surgery later. You can read about that here. ("previously excised" means previously cut off)
These inflamed areas have also been treated with radiation and some veterinarians claim success in doing so. I personally doubt that any improvements that might have occurred subsequent to radiation were due to more than the distraction of the procedure or some undiagnosed, underlying cause (such as infection or cancer) that could have been treated less drastically. But you can read about the radiation procedure here.
Antibiotics may be helpful if the lesion has developed pussy areas or tracts or if moist bandages have encouraged bacterial growth. But they will not cure true acral lesions. When bandages are used, an antiseptic powder (such as boric acid or povone iodine powder) is probably a better option.
Other veterinarians have injected corticosteroids (such as methylprednisolone acetate) into and under the affected area. I do not feel that this is a helpful (or safe) way of dealing with the problem. Other medications that block the immune process, like Atopica are also an inappropriate way of dealing with this problem. Somewhere, sometime, just about everything has been tried - from acupuncture to cobra venom. An occasional dog will appear to improve after these treatment, but there is really no scientific evidence that the improvement was the result of what was done. You can find references to those attempts in an article here.
What Is The Outlook For My Pet ?
The good news is that this condition is generally no more than an unsightly blemish. The bad news is that veterinarians may not be able to cure it once it becomes a well-established habit. Again, the earlier it is recognized and treated the more hope there is for a permanent cure. If the problem is truly an acral granuloma and if you can keep your pet from licking the area - it will almost certainly heal. I personally greatly prefer using mechanical and behavior modification means of doing that rather than powerful oral or injectable medications.
Can One Dog Catch This Problem From Another ?
There is no evidence that this is a transmissible disease. But in any case, it is always wise to wash your hands after touching these lesions (wounds). There is also always the possibility of producing “super resistant” bacteria that can spread to other family members if this problem is treated overzealously with antibiotics.
Are Some Of These Problems Rooted In My Pet's Genes ?
The Broad Institute has made great progress in mapping the complete gene catalog (genome) of dogs. They have also made great progress in understanding which genes favor compulsive and aggressive behavior in dogs. (ref1, ref2, ref3, ref4) That does not mean that love, patience, training and/or medication can not improve your pet's situation. It might also help you understanding that we pet owners, and our pet's earlier traumas might not be entirely responsible for our pet's current psychological issues. Many pet owners who write to me feel that guilt and frustration. There is really no reason for them to feel that way. Try not to.