1. Nail conditions Mrs Sue Paterson MA VetMB DVD DipECVD
RCVS and European Specialist in Veterinary Dermatology
Rutland House Veterinary Hospital, St Helens, UK

2. Structure of the canine claw courtesy of Patel, Forsythe
Fig. 10. Foal had congenital defects of the intestinal tract on necropsy as well (Case material: Carlson, University of California, Davis).
© This slide is made available for non-commercial use only. Please note that permission may be required for re-use of images in which the copyright is owned by a third party.
Structure of the canine claw courtesy of Patel, Forsythe

3. Nail terms Onychoclasis – breaking of the claw
Onychocryptosis – ingrown nail
Onychodystrophy – abnormal claw formation
Onychogryphosis – hypertrophy and abnormal curvature of the claw
Onychomedesis – sloughing of the claw
Onychomalacia – softening of the claw
Onychomycosis – fungal infection of the claw
Onychorrhexis – longitudinal striations associated with brittleness and breaking of the claw
Onychoschizia - splitting or lamination of the claw
Paronychia – inflammation or infection of the claw fold

4. Paronychial disease – involves the nail fold
Nail disease – involves the nail
Fig. 10. Foal had congenital defects of the intestinal tract on necropsy as well (Case material: Carlson, University of California, Davis).
© This slide is made available for non-commercial use only. Please note that permission may be required for re-use of images in which the copyright is owned by a third party.

5. Important to differentiate between diseases of the nails beds and those of the nails Investigation and therapy of each disease is different

6. Disease of the nail bed – Dogs
Bacterial paronychia
secondary to allergy,
endocrine disease,
demodex
Malassezia paronychia
secondary to allergy or
endocrine disease
Demodectic paronychia
Leishmaniasis
Neoplastic Immune mediated S.L.E. Pemphigus foliaceus Bullous pemphigoid Drug eruption

7. Disease of the nails – Dogs
Congenital disease – DEB, Ichthyosis
Traumatic injury –RTA
Onychomycosis
Vasculitis
Dermatomyositis
Leishmaniasis
Idiopathic lupoid onychodystropy

8. Disease of the nail bed – Cats
Bacterial paronychia
secondary to allergy or
FIV, FeLV
Malassezia paronychia
endocrine disease
Viral paronychia
calici, herpes, pox
Demodectic paronychia
S.L.E. Pemphigus foliaceus Bullous pemphigoid Drug eruption Neoplastic met bronchial carcinoma

9. Disease of the nails – Cats
Traumatic – RTA
Onychomycosis
Vasculitis
Idiopathic onychodystrophy

10. Investigation of nail disease
History
Physical examination
Dermatological examination

11. Examination of nail
Examination of the nail / nail bed is important to establish which structure is affected
In some case paronychial disease and nail disease is present concurrently

12. Investigation of nail disease
Diagnostic tests
Samples from nail beds – skin scrapes, hair plucks, cytology
Nail trimmings for dermatophytes culture
Removal of nail for histopathology ?

13. Fig. 10. Foal had congenital defects of the intestinal tract on necropsy as well (Case material: Carlson, University of California, Davis).
© This slide is made available for non-commercial use only. Please note that permission may be required for re-use of images in which the copyright is owned by a third party.
BIOPSY TECHNIQUES

14. Symmetrical lupoid onychodystrophy

15. Approach to a nail case History – breed, age, life style
Physical examination – signs of systemic ill health
Dermatological examination – evidence of involvement of other areas, e.g. face, other mc junctions

16. Symmetrical lupoid onychodystrophy
Aetiology
Uncommon to rare immune mediated claw loss
Usually young adult - middle aged dogs esp. GSD
Initial signs are of loss of 1 – 2 nails but disease is progressive and over weeks to months all claws will slough
Replacement claws are usually misshapen, soft, brittle, friable and will slough again without therapy
Feet usually painful and dog may be lame
This is a diagnosis of exclusion

17. Initial diagnostic tests
Cytology of any exudate
Bacterial culture of exudate when appropriate
Fungal culture of claw clippings
Bloods if systemic disease is suspected
Biopsy of skin if generalised disease is a potential differential diagnosis
Histopathology of P3

18. Initial diagnostic tests
Diagnostic histopathology of P3
Hydropic degeneration, apoptosis of individual keratinocytes in basal cell layer, pigentary incontinence, lichenoid interface dermatitis

19. Symmetrical lupoid onychodystrophy
Differential diagnosis Dermatophytosis Trauma Autoimmune disease e.g. pemphigus foliaceus Immune mediated disease – vasculitis, dermatomyositis

20. Further investigation
A diagnosis of onychodystrophy is made by exclusion of other causes -
Removal of all nails by traction should be undertaken
Dog anaesthetised with full analgesia.
The feet are clipped and prepared surgically
Each nail is grasped in turn with a pair of artery forceps and is twisted and pulled to remove it
Cultures taken from nail bed and nail submitted for fungal culture

21. Post operatively Dog feet are dressed & hospitalised for 48 hrs
Antibiotics given usually Cephalexin 25mg/kg bid plus analgesia Tramadol 2 – 5 mg / kg bid
After 24 hours dressings removed, feet gently cleaned – under GA if necessary. No further dressing are applied
Dog sent home initially with more antibiotics, pain relief and a large buster collar

22. 10 day recheck – ongoing tx
At 10 days analgesia and antibiotics can be discontinued
Ongoing treatment
Immune modulators
Nutritional supplements

23. 10 day recheck – ongoing tx
Immune modulators
Tetracycline or Doxycycline and Niacinamide
Glucocorticoids
Azathioprine
Ciclosporine
Pentoxyphylline

24. 10 day recheck – ongoing tx
Nutritional supplements
Omega 6 and /or omega 3 EFAs
Biotin

25. Tetracycline/doxycycline + niacinamide
Dogs < 15kg Tetracycline 250mg with Niacinamide 250mg tid
Dogs > 15kg Tetracycline 500mg with Niacinamide 500mg tid
Alternative to tetracycline - Doxycycline 10mg/kg sid
Precise mechanism unknown.
Tetracycline and Doxycycline both have anti-inflammatory and immune modulating activity
Niacinamide shown to have range of anti-inflammatory effects
Combination useful in DLE and pemphigus as well as lupoid onycodystrophy

26. Glucocorticoids
Have been shown to be useful in many case, only start once any bacterial or fungal infection has been resolved
Dose rate is very variable
Low dose therapy
Prednisolone 0.5mg/kg sid/eod po
High dose therapy
Prednisolone 2.0mg/kg sid/eod po
Gastric protectants useful if using the higher dose rate

27. Azathioprine / Cyclosporine
Both drugs can be used with or to replace steroids
Azathioprine 2mg/kg po sid up to 3 months until remission is seen then eod.
Dogs must be monitored for changes in liver function and bone marrow
Cyclosporine 5m/kg po sid up to 3 months until remission and then taper to eod or biw
Monitoring not necessary in a healthy dog, but cost may be prohibitive

28. Omega 6 and /or omega 3 EFAs
Essential fatty acids increasing the suppleness of thin, brittle nails.
Important in dogs when exercising and when nails are cut
Dose 300mg EPA / 10kg daily or
200mg GLA / 10kg daily

29. Pentoxiphylline 10-24 mg/kg bid/tid
Immunodulatory drug in man useful for treatment of peripheral vascular disease and vasculitis
Been shown to be useful for similar conditions in dogs

30. Biotin - Human studies
Biotin supplementation increases nail thickness by 25 percent in 63% of a group of patients with brittle nails. (Floersheim GL 1989).
Patients taking biotin daily for 3-6 mths had reduced brittleness & splitting (Hochman LG et al 1993).
Increased nail thickness as identified by scanning EM was recorded after biotin supplementation. (Colombo VE et al 1990).

31. Typical combination therapy
Essential fatty acids GLA 200mg/10kg sid po or 300mg/10kg sid po
Biotin mg daily/ dog
Prednisolone 0.5mg/kg eod po
Pentoxyphylline 10mg/kg tid po
Continue therapy for 6 weeks then reassess
If dog making progress consider with drawing Pentoxyphylline, continue with other drugs long term

32. Failure to respond to therapy
Switch to a different immune modulator
Azathioprine
Ciclosporine
Tetracycline / doxycycline with niacinamide
Surgical intervention to amputate all of the claws.