Introduction
a very frustrating skin disease found mostly
in dogs is called acral lick dermatitis (ALD),
commonly know as a lick granuloma. Dogs with this disease lick incessantly,
causing chronic skin lesions of the limbs.
Many aspects of aLD are similar to
allergic
dermatitis in general.
This page will give you an opportunity to link to the aspects of the
allergic dermatitis page that also apply to aLD.
Pathophysiology
Constant licking of the feet leads to hair
loss and irritation of the skin.As
the problem progresses the skin becomes ulcerated and infected. As
the ulceration progresses nerves become inflamed and the area becomes pruritic
(itchy), so much so that the dog can not stop licking. A
viscious cycle develops and the condition becomes chronic.
It is theorized that some dogs get
into such a licking habit, and actually derive pleasure from it, that
once the initiating cause is eliminated they still continue to
lick.
Cause
This is a disease that has many factors involved
with the cause. Some of these 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. The most common causes
include:
Allergic Dermatitis
This is considered the primary cause of the
problem. We have a detailed page on allergies
to learn more about this complex problem.
Arthritis
Joints in the area of the lesion can be
painful, causing excessive licking of the skin over the area.
Since the licking does not cure the problem, it continues,
eventually causing significant skin lesions.
Neuropathies
Inflammation of the nerves under the skin in
the area of the lesion can cause significant discomfort, again
leading to excess licking.
Neoplasia
Skin cancer can cause chronic lesions that are
uncomfortable and lead to chronic licking.
Fungal Infections
Deep seated fungal infections, including
blastomycoses and Ringworm
can initiate the problem.
Ectoparasites
External parasites like scabies
and demodex
are also potential causes.
Psychogenic
This is a catch-all term for psychological
causes that are thought to be involved. They include boredom and
stress factors. Similarities have been made between this and
obsessive-compulsive disorders in people. When you see a dog
licking incessantly at his legs you can see why this comparison is
made.
Symptoms
The most consistent symptom in pets with ALD
is excessive licking of the extremities, especially the front and rear legs.
Lameness could occur due to infected skin or even arthritis. If the skin infection
is serious enough there might be a lack of appetite (anorexia) or lethargy.
Diagnosis
The correct diagnosis for ALD
does not come easy, so a thorough
approach is needed. In every disease
we encounter we follow the tenet's of the diagnostic process to ensure that
we make an accurate diagnosis, and that we do not overlook some of the diseases
that are also encountered in pets as they age.
1.
Signalment
Several breeds are prone to ALD:
- Doberman pinscher
- Great Dane
- Golden retriever
- Labrador retriever
- German shepherd
- Boxer
- Dalmatian
- English Setter
- Shar Pei
- Weimaraner
2. History
ALD usually starts
appearing when dogs reach at least 5 years of age, especially the above breeds.
When it first appears it might coincide with allergy symptoms that are seasonal
in nature.
3. Physical Exam
This is a picture of the classic finding in a dog with ALD.
If the skin infection is severe enough
there might be swelling (cellulitis) due to the infection.Also,
the lymph node that drains the affected area might be enlarged and there
might even be a fever.
4. Diagnostic
Tests
Diagnostic tests are important since 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.
Skin
Scraping
It is important to do a skin
scraping in many cases of ALD
because the symptoms and lesions commonly mimic those of ectoparasites like
demodex
or scabies.
Fungal Culture
Ringworm lesions can look similar to ALD
lesions. In Ringworm there is usually not as much licking.
Radiography
If we suspect the licking is
from a painful joint we can sometimes make this diagnosis from
an x-ray.
Skin Biopsy
This test is used to help differentiate
skin tumors or deep fungal infections as the initial cause of ALD.
Fine Needle
aspiration
As an alternative
to an actual skin biopsy we can do a simpler test called a fine needle aspirate.
In this test we use a syringe with a tiny needle to take a sample of the
affected area. This sample is put on a microscope slide for analysis by
one of our pathologists.
It does not require general
or local anesthesia and can be performed during an office call.
Only a small amount of tissue is sent to the lab for analysis,
so it is not always possible to make a complete diagnosis this
way.
Bacterial
Culture
This test will give us an
indication of the type of bacteria involved. Since the top of
the lesion is contaminated with many bacteria, some of which
are not part of the problem, a culture is performed on biopsy
samples that are taken in a sterile manner.
Allergy Test
Allergies can be a major component of ALD.
Please refer to our allergic dermatitis page due learn about allergy
testing.
Treatment
ALD tends to
be a chronic disease that leads to significant frustration. The
wide variety of treatments that are used to treat ALD are an indication of the
complexity of this disease and the fact that many different causes, some working
in tandem, are involved.
Flea Control
We can not emphasize the
importance of proper flea control in any pet that has a skin
condition since we live in a flea endemic area year round. Even
pets that are 100% indoors are possible flea victims.
The products available today are a significant
improvement over flea control products in the recent past. They are economical,
safe, effective, and very convenient. The two main products we recommend are
Advantage© and Program©. We have detailed
brochures on each to explain how they work, please ask one of our receptionists.
There is a new product that
will be of significant help in outdoor dogs and cats. It is called
Revolution©. In addition to treating fleas, it
treats heartworm,ear
mites, and
internal
parasites (depending on
the species). This is a huge spectrum of control, and will
probably become the future standard. We also have detailed
brochures on this product.
Anti-inflammatories
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. There is a section there
on its proper
use.
As an option to using
cortisone to minimize the licking we suggest the use of elizabethan collars.
A good option
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.
Antibiotics
Oral antibiotics are probably the most important
treatment we have for ALD.
In some cases we need to use them for 4-6 months due to the chronic nature
of the problem. It is important to continue them for at least 3 weeks after
the skin looks healed. In some pets we put them 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
We have had success using our
laser
machine in the
treatment of this problem. It usually takes at least 3 treatments,
and in some cases can be a significant help in minimizing the
licking.
This Labrador has an ALD
lesion on top of its rear foot area. It is been prepped or laser
treatment.
The laser is being used at a
light setting with an intermittent pulse.
The appearance of the lesion
immediately post laser treatment.
Antifungals
If a deep seated fungal
infection is diagnosed we will use oral fungal medication for an
extended period.
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
give on a long term basis, usually once per month once the allergy
is improving.
Food allergy
We recommend feeding hypoallergenic
diets to any pet that has a skin
condition caused by an allergy.
Food Supplements
Some allergic dogs and cats
scratch less when supplemented with essential fatty acids. The
main ones we use are Derm
Caps and EFa-Z.
Surgery
This is not a rewarding way to treat ALD since the problem
commonly recurs after the surgery.
Topical Medications
It is a natural tendency to want to use topical
medication only on a skin problem. If used in combination with
long term oral antibiotics this topical medication can be
beneficial. They are not effective when used alone.
Behavioral Modification
Medications
Some dogs are compulsive lickers without any obvious cause.
Some veterinarians believe that the incessant licking in ALD is similar
to the exaggerated grooming habits of people with obsessive-compulsive disorders.
These medications are helpful, but do have the
potential to cause side effects, especially when used with other
medications. One of our doctors will let you know if they apply in
your situation.
Veterinary Orthopedic Manipulation
An additonal treatment modality used to
treat ALD is VOM.
It is a non-invasive and non-painful way to stimulate the nervous system
to stop the sensation that is causing the problem.
Prognosis
ALD has a guarded prognosis. An early and accurate
diagnosis (when one is apparent) offers the best option by instituting proper
medication before the problem becomes so chronic that treatment is only marginally
effective.
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