Symmetric Lupoid Onychodystrophy
Symmetric Lupoid Onychodystrophy
is the most common immune-mediated disease that results in severe claw problems
in otherwise apparently healthy dogs. The disease causes the immune
system to become overactive, attacking the nails and nail beds, creating
fissured or split nails that never totally heal. Young adult and middle-aged
German Shepherd dogs appear predisposed to this disease. SLO can appear
in all breeds, including crossbreeds and mixed-breeds, although some breeds
seem to be more susceptible than others. It is not infectious or contagious
- other dogs which come into contact with it cannot contract it. It
appears to be spontaneous, and there is no evidence of an hereditary factor
- because of the absence of studies and the small number of known cases though,
there is little proof of this other than anecdotal evidence.
The claw is made up of three general layers. The outside part is hard
dead material. In the centre of the claw is the living part, complete with
nerves and blood supply, called the ‘quick’. Between the two is a layer
of spongy material. The nail forms at its root, which is located deep
inside the toe near the endmost bone of the toe. The newly formed nail grows
out towards the external part of the toe for about 3-4 months before it emerges
and becomes visible. It takes about 9 months for a nail to grow from root
to full length. SLO damage occurs while the claw is forming
at the root, although the claws usually don’t shed until the damaged part
emerges from the toe. As a result, damage you see now actually occurred several
months ago, and the results of treatment can’t be assessed for some months
after it’s started.
There is usually an acute onset
of nail loss. Initially, one or two claws are lost, but over a course
of a few weeks to several months, all claws slough. Partial regrowth
typically occurs, but claws are misshapen, hollow, soft or brittle, discolored,
and friable and often slough again. Other symptoms may include: receding quicks,
secondary bacterial nailbed infections occur (often with a strong smell),
claw splitting (usually down the back of the claw), pain, distorted/twisted
claws and lameness. The affected feet are often painful and/or itchy. Affected
dogs are otherwise healthy.
This is not the kind of disease
that veterinarians see every day, so do not be surprised when a definite diagnosis
takes a while to reach. The information regarding the diagnosis and
treatment of all veterinary diseases is too vast for any one veterinarian
to memorize. Veterinarians are usually resourceful getting information
about anything they may not be familiar with, so give your veterinarian a
chance to help your dog.
Other diseases that need to be considered in the differentials include
fungal and bacterial claw infections, autoimmune skin disorders, drug reaction,
and vasculitis. In most instances a diagnosis can be made from visual
inspection, however a biopsy of the digit is required for definitive diagnosis.
There are three main methods of diagnosis – diagnosis by aetiology (the
characteristics of the disease), diagnosis by response to treatment, and
diagnosis by biopsy.
Diagnosis by aetiology
Someone who is familiar with SLO may well be able to make a diagnosis of
SLO on sight, particularly if it follows the typical characteristics of the
disorder. The possibility of fungal and bacterial infections needs to be eliminated
first, as these are more common and can produce similar symptoms. Unsuccessful
treatment of bacterial and fungal infections increases the likelihood that
SLO is the cause.
Diagnosis by response to treatment
In many cases, where SLO is suspected, the owner or vet may decide against
a biopsy and choose instead to commence treatment immediately. The treatments
for SLO are quite specific, and usually if the problem responds to the treatment
one can consider the diagnosis confirmed.
Diagnosis by biopsy
Diagnosis by biopsy is done by taking a sample of the root of an affected
claw and examining it under a microscope. This method is easiest if the dog
had affected dew claws, since a dew claw can easily be removed for study.
Until recently, taking a biopsy from a claw other than the dew claws has
been a major step for most owners, as it involves amputating the distal phalanx
(last bone) of the toe.
More recently there has been a new biopsy technique involving using a biopsy
punch to get a sample of the root.
A firm diagnosis can only
be reached by the biopsy of a claw, dewclaws usually being used for this.
In the absence of an available dewclaw it is necessary to amputate a toe at
its bottom joint in order to do the biopsy. In many cases, this is
considered an extreme step to take, and is not strictly necessary. If the
dog is showing signs of SLO, treatment using the latest protocols can be
started - if they work, it largely confirms the diagnosis, even without the
Treatment is challenging, and can take as long as six months to see
positive results. Treat any secondary infections with appropriate antibiotics.
SLO is commonly treated with daily oral fatty acids and oral Vitamin
E. Noticeable nail regrowth should be noted within 3 months of initiating
this therapy. Other treatments include Tetracycline and Niacinamide, pentoxifylline,
and for more severe refractory cases Prednisone and other nonsteroidal immunosuppressive
drugs can be utilized. Removal of claws as they become loose can help
to alleviate pain, but generally isn't necessary. Although there are
few studies to scientifically confirm the results, the treatment appears
to be effective. A food allergy has been identified in a few cases of
this disease, so it may be appropriate to go through a strict , 8-12 week
hypoallergenic food trial. Bathing the feet in saline or dilute antiseptic
solution after walks can often help. Dog boots can be used to try
to prevent lameness during exercise when damaged tissues are painful. A
number of dogs have also been diagnosed with Hypothyroidism at the same
time SLO has been diagnosed. A full thyroid panel may be indicated
to evaluate this common hormonal disease. Once the disease is in remission,
supplementation may need to be continued for life to prevent relapse.
The prognosis for nail regrowth is good, although some nails may remain
deformed. In some dogs, therapy can be discontinued after 6 months. In other
cases, long term maintenance therapy is needed to maintain remission.
Canine Symmetrical Lupoid Onychodystrophy
The above information is simply informational. It's intent is not
to replace the advice of a veterinarian nor to assist you in making a diagnosis
of your pet. Please consult with your own veterinarian for confirmation of
any diagnosis. Your pets life may depend on it.