04.Jun 2021

SLO in dogs - often undetected and very painful


Overview: Canine Symmetrical Lupoid Onychodystrophy (SLO)

Systemic lupoid onychodystrophy (also called systemic lupoid onychodystrophy/onychitis) is a clinical syndrome affecting dogs, that involves severe claw malformations incl. claw loss.

There are no other dermatological changes.


Strictly speaking, SLO denotes the clinical and histopathological appearance of immune-mediated claw lesions. The actual causes are still unknown, however.

Presumed primary causes include a genetic component (frequently appearing in Rhodesian Ridgebacks, Bearded Collies, German Shepherds and Setters) as well as CAD, feed intolerances, and trauma.
SLO therefore must be described as idiopathic in most patients.

What are the clinical signs of dogs with SLO?

The typical symptoms of symmetrical lupoid onychodystrophy are:

  • Initial increased licking of affected claws, severe pain, and thus avoidance of physical activity
  • First lesions appear on 1-2 claws: Claws become brittle, break easily, show malformations, fall out, or must be removed.
  • The disease advances to all 4 paws within a few weeks
  • Regrowing claws will display the following: Malformations, splitting, with renewed loss of claw tissue
  • Frequently concomitant secondary infections (claw bed infections, including concomitant infections with P. aeruginosa), phalanx III sometimes also affected
  • No other dermatological or systemic changes (possibly lameness and reduced general well-being from pain)

How is a diagnosis of SLO made?

  • Thorough medical history incl. progression of disease
  • The ruling out of other causes of the symptoms (e.g. dermatomycoses, infectious diseases such as leishmaniasis, mineral deficiencies, other immune-mediated diseases)
  • For a clear diagnosis: Histo-pathological examination of the claw matrix with adjacent tissue (amputation of the claw incl. phalanx III or preferably punch biopsy according to Müller/Olivry: less invasive and fewer postoperative complications)
  • Elimination diets or diagnostic therapies, for example with corresponding antimicrobiota, are also sometimes recommended


A combination of local (topical) and systemic treatment must be individually developed and often continuously adjusted by a dermatologist.

The following medications and treatment options may be used for cases of SLO:

  • High doses of essential omega-3 fatty acids (essential use)
  • Various antibiotics like tetracycline, doxycycline
  • Niacinamide (vitamin B3), vitamin E and other B vitamins like biotin
  • Pentoxifylline
  • Analgesics as needed
  • Immunosuppressants as needed: Prednisolone or cyclosporine (if possible, not as long-term treatment)
  • Additional topical treatment with antiseptics, incl. pedicures
  • Avoid excessive physical stress in the juvenile phase (a suspected trigger is excessive mechanical irritation of the claw area).
  • Partly detached claws often will need to be removed under sedation or short anaesthesia


In some cases the disease has been observed to subside (e.g. successful feed changes).
Usually, however, it is a chronic disease often involving life-long, regularly modified therapy. After successful treatment, recurrences are nevertheless to be expected.

Owners of affected dogs must exercise a high degree of patience and compliance, in addition to possible financial burdens. However, the restored quality of life that our four-legged patients experience makes this effort worthwhile for everyone involved.

Do not hesitate to contact our DiploVets-affiliated ECVD/ACVD Diplomates with any questions you may have regarding diagnostics or treatment.


Bibliography: Upon request

Author of the article:

Veterinarian med. vet. Julia Brüner