Symmetrical Lupoid Onychodystrophy (SLO), also known as canine symmetrical onychomadesis or symmetric lupoid onychitis, is an uncommon inflammatory disease affecting the claws of dogs. It is characterized by abnormal claw formation (onychodystrophy), sloughing of the claws (onychomadesis), and inflammation of the claw unit (onychitis). Diagnosing and managing SLO presents a significant challenge for veterinary dermatologists.
Understanding Symmetrical Lupoid Onychodystrophy (SLO)
SLO typically affects young to middle-aged dogs, with the onset of symptoms usually occurring between 2 and 8 years of age, though it can also be seen in puppies and senior dogs. Certain breeds, such as Gordon Setters and German Shepherd Dogs, appear to be more predisposed to developing the condition. The exact cause of SLO remains unknown, but it is suspected to be an immune-mediated disease with a genetic component. This means that the dog's own immune system mistakenly attacks the nail matrix, leading to abnormal nail development.
Clinical Signs and Symptoms
The initial signs of SLO are often related to pain (onychalgia) and discomfort in the paws. Affected dogs may exhibit excessive licking of the paws or lameness. Owners may also notice that the claws are splitting (onycholysis), brittle, or falling off (onychomadesis). Over a relatively short period, all nails on all paws are variably affected. Claws regrow, but they will be misshapen, dry, brittle, and crumbly. Bleeding (hemorrhage) beneath a retained nail may be recognized. Secondary bacterial infections may be seen as well as regional lymphadenopathy.
Diagnosis
Diagnosing SLO involves a combination of clinical observation, history, and diagnostic testing to rule out other potential causes of nail disease. Your veterinarian might be able to make a presumptive diagnosis of SLO due to the appearance of the toenails and your dog’s history. A culture of the affected nail can rule out bacteria, fungus, or ringworm. X-rays should also be done to ensure that the underlying bone is healthy and no evidence of cancer is seen. Depending on the severity of the nail bed lesion, sometimes a digit amputation at the dewclaw is performed for biopsy. The nail that falls off will not provide a diagnosis; the nailbed is needed for it.
Treatment Strategies for SLO
Treatment of SLO is aimed at managing the symptoms, controlling secondary infections, and suppressing the immune system to promote healthy nail regrowth. Unfortunately, no single treatment protocol has been established for treating this uncommon condition. The mainstay of treatment is aimed at suppressing the immune system. It often takes six to 12 weeks for the toenails to start to improve. Overall prognosis once SLO is treated is good, but nails may continue to break easily and remain deformed. It is important to give all medications and supplements as prescribed by your veterinarian. Frequent nail trims are very important and should be done every one to two weeks for the rest of your dog’s life.
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Addressing the Acute Phase
The acute phase of SLO is characterized by inflammation, pain, and sloughing of claw plates. Loose claws have to be removed and secondary infections treated. Management during this phase focuses on:
- Pain relief: Non-steroidal anti-inflammatory drugs (NSAIDs) or other pain medications may be prescribed to alleviate discomfort. The dogs received carprofen 2 mg/kg BID for five days following the removal of claw plates in one study.
- Infection control: Secondary bacterial or yeast infections are common in SLO. The owners were instructed to use socks on the dog’s paws as long as the claw beds were sore and to wash the paws with antibacterial shampoo daily if exudate was present.
- Claw removal: In some cases, the nail plate will need to be removed under heavy sedation or anesthesia, to reduce discomfort and/or the risk of the claw getting caught on something in the environment.
Long-Term Management
The goal of long-term treatment is to allow claws to re-grow with normal quality and to achieve life-long lack of recurrence. Long-term management strategies include:
- Dietary Modifications: Nutritional support plays a crucial role in managing SLO.
- Omega-3 Fatty Acids: Bergvall [3] demonstrated positive effects of omega-3 and omega-6 supplementation. Ziener et al [4] compared the effect of fish oil treatment to the effect of cyclosporine treatment in a population of Gordon setters and English setters diagnosed with canine symmetrical onychomadesis. All dogs were fed a high omega-3 fatty acid diet. One group was supplemented with fish oil and the other with cyclosporine. All dogs, except 1 in the cyclosporine group, showed an improvement in the number of normal claws. The fish oil group improved from a mean of 0/18 normal claws to 14/18 and the cyclosporine group improved from a mean of 5/18 to 15/18.
- Elimination Diet: Adverse food reactions have also been proposed as a possible factor. All dogs were fed Eukanuba Veterinary Diets (EVD) Dermatosis® exclusively from the time of initiation of treatment and for the following six months. In addition, the owners were allowed to give their dogs’ potatoes and low fat white fish, as these were ingredients in the diet, but nothing else. EVD Dermatosis® was fed as an elimination diet during the study because neither of the owners had previously given their dog catfish or herring, which are the protein sources in EVD Dermatosis®.
- Medications: A variety of medications may be used to suppress the immune system and promote nail regrowth.
- Tetracycline or doxycycline with niacinamide: Mueller et al (3) considered tetracycline or doxycycline and niacinamide useful combinations for the treatment of SLO. The combination of tetracycline and niacinamide plus fatty acid supplementation and a high fatty acid diet is the initial treatment of choice at our facility. The client should be reminded that niacinamide is to be administered and not niacin. Tetracycline and niacinamide are both dosed at 500 mg, q8h for patients > 10 kg and 250 mg of each, q8h for patients < 10 kg.
- Cyclosporine: In addition, a pilot study using cyclosporine in three dogs was conducted prior to initiating the current treatment trial. All dogs had re-growth of normal claws after treatment with cyclosporine for six months (unpublished data).
- Prednisolone, pentoxifylline and azathioprine: traditionally, different immune-modulating drugs have been used to treat dogs diagnosed with symmetrical onychomadesis and complete or partial remission has been achieved [1]-[5].
- Regular Nail Trimming: Frequent nail trims are very important and should be done every one to two weeks for the rest of your dog’s life.
- Paw Hygiene: Diligent claw treatment and paw hygiene recommended.
Fish Oil vs. Cyclosporine: A Comparative Study
A randomized treatment trial was conducted to compare the efficacy of fish oil supplementation and cyclosporine in treating symmetrical onychomadesis in Gordon and English setters fed a diet rich in omega-3 fatty acids.
- Study Design: Twelve Gordon setters and one English setter diagnosed with symmetrical onychomadesis were recruited for a treatment trial at the first author’s clinic in Norway from 2008 until 2010. All dogs were fed Eukanuba Veterinary Diets (EVD) Dermatosis® exclusively from the time of initiation of treatment and for the following six months. Six Gordon setters and one English setter were treated with 5 mg/kg cyclosporine once daily for six months and seven Gordon setters were treated with 10 ml Dr Baddaky fish oil® once daily for six months.
- Results: There was a statistically significant improvement in the number of healthy claws after six months of treatment with a median increase of 13.5 claws for both groups. However, there was no statistically significant difference between the two groups regarding the differences in number of healthy claws after six months of treatment. Dogs in the cyclosporine group had a median increase of 10 healthy claws after six months of treatment while the median for the fish oil group was 14.
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tags: #lupoid #onychodystrophy #diet #treatment