1. What is symmetrical lupoid onychodystrophy (SLO)?

SLO is a disease found only in dogs where the claws are brittle, misshapen and can slough off.  It is also sometimes called symmetric onychomadesis, or onychitis.  There are several breeds predisposed to SLO (German Shepherd, bearded collie, Gordon setter) but it can be seen in many others and usually affects adult dogs between ages 2-9 years old.  Pathogenesis is thought to be an immune-mediated attack on the stem cells located at the base of the claw and treatment is aimed at stopping this attack and strengthening the claw.

2. Differential diagnoses to consider:

• May affect all four paws
  • Vasculitis
    • Double check paw pads, tail, pinnal tips, face
  • Dermatophytosis
    • Can be isolated to claws, but can affect any keratinized structure
      
      
  • RARE to affect claws in this way: endocrinopathies, pemphigus foliaceus and other pemphigus complex diseases, keratinization defects, nutritional abnormalities, leishmaniasis
• Unlikely to affect all four paws
  • Trauma
  • Neoplasia

3. Diagnostic testing:

• Cytology or culture of claw exudate
  • Often claw beds are infected at the time of diagnosis, contributing to pain and licking.  
  • For treatment, I like cephalexin (30mg/kg q12h x 30 days) and diluted chlorhexidine paw soaks if the dog will tolerate it
• Claw shavings for dermatophytosis testing
• Histopathology
  • Histopathology is required to confirm diagnosis but the junction of the skin and claw base are required for finding diagnostic changes.  This can mean submitting the entire third phalanx (the “quick”, P3) or a very carefully placed punch biopsy of clawbed.  A dewclaw can be removed for diagnosis if affected, but I don’t routinely biopsy these.  It is not tough to diagnose clinically and to rule out the other diseases!
• Elimination diet trial 
  • Some dogs have concurrent food allergy symptoms, disease improves with hydrolyzed diet and recurs with food challenge
• Thyroid testing if concurrent symptoms of hypothyroidism present

4. Treatment:

• Manual removal of loose or partially detached claws
  • Treatment will NOT re-attach a loose claw.  These need to be removed to improve patient comfort and allow healthier claw to try to grow in once treatment started
    
    
  • Sedation +/- local anesthesia
    • Ring block on limb with avulsed claws prior to removal¹
    • If wiggling when palpating, use hemostats to pull and remove
    • Bandage paw after for 24-48 hours to minimize licking of exposed P3

• Antibiotic therapy for bacterial paronychia, onychitis
• Supplements
  • I ALWAYS use these! Either alone or in addition to immunomodulators
  • Omega 3/Omega 6 fatty acid supplementation
    • EPA 180mg/5kg body weight q24h
    • EPA+DHA combined 50-250 mg/kg q24h 
      • Elanco Free Form Snip Tips Fatty Acid Capsules for Small Dogs & Cats
      • Dechra Eicosa3FF Snip Caps
    • One report of 5 dogs treated with Omega-3 and Omega-6 fatty acids only with resolution of lesions.  Most of them relapsed when the supplement was discontinued, as this is typically a lifelong disease.²
  • Vitamin E: 200-800 IU/dog q12h
• Immunomodulatory therapy
  • Pentoxifylline
    • This is my first line of treatment in addition to supplements
    • 20 mg/kg q8-12 hours monitoring for GI upset
    • Usually start at q12h dosing and increase to q8h if owner able to dose mid-day and dog can tolerate without GI uspet 
    • Contraindications: concurrent bleeding disorders
  • Doxycycline/Niacinamide
    • Used to be a “go-to” treatment for most lupoid dermatoses but falling out of favor with rising concerns for antibiotic resistance
    • If choosing this, make sure to use niacinamide (vitamin B3), NOT niacin which can be hepatotoxic to dogs
    • Doxycycline: 5-10 mg/kg PO q12h
    • Niacinamide: 
      • <15 kg body weight: 250mg q8h
      • >15 kg body weight: 500mg q8h
  • Glucocorticoids
    • 1-2 mg/kg/day prednisone can be used short term to quickly stop inflammation and immune mediated process
    • I reach for this if dogs are really painful despite removal of sloughing claws
  • Cyclosporine (modified)
    • 5-10 mg/kg/day
    • Must be “modified” cyclosporine for best absorption, but brand name Atopica may have the best absorption in dogs
    • Keep in freezer to minimize nausea
  • Azathioprine
    • Reports of use.  I have never needed this drug and would have to be really desperate to use for SLO. 

5. Prognosis:

Prognosis is good but quality of life is affected when claws are sloughing or painful.  Most dogs will require lifelong treatment.  It is important for owners to understand that one drug does not always work for every dog with SLO.  Sometimes we have to attempt a few different protocols before finding success.  Success also looks different for every dog and it can take 3-6 months of claws growing out before we realize a treatment isn’t working.  My primary treatment goals are NOT for the claws to look normal, but for the dog to be comfortable, not licking or getting claw infections and for claws to not be sloughing off or becoming loose.  
 

Claw terminology³

References:

1. Douglas, Hope, Stephanie Welsh, and Ciara Barr. "Clinical techniques in veterinary dermatology: regional anaesthesia of the canine and feline distal limb." Veterinary Dermatology 32.1 (2021): 90-e17.
2. Bergvall. "Treatment of symmetrical onychomadesis and onychodystrophy in five dogs with omega‐3 and omega‐6 fatty acids." Veterinary Dermatology 9.4 (1998): 263-268.
3. Auxilia, S. T., P. B. Hill, and K. L. Thoday. "Canine symmetrical lupoid onychodystrophy: a retrospective study with particular reference to management." Journal of small animal practice 42.2 (2001): 82-87.

About the Guide: Karly Robinson, DVM, MS, DACVD

I completed my undergraduate degree and veterinary school at Auburn University. I then completed a rotating internship at a private practice hospital outside of Nashville, TN and returned to Auburn for my dermatology residency (War Eagle!). My board certification was in 2021 and I am now practicing near my hometown in Santa Rosa Beach, FL with a private practice specialty group.