IDIOPATHIC nasodigital hyperkeratosis is a condition that manifests as excessive accumulation of keratin on the dorsum of the nasal planum and/or footpads. Brachycephalic breeds and cocker spaniels may be predisposed.
The characteristic sign is thickened, dry and hard keratin accumulating in the sites mentioned. In the nose the cause may be a failure of keratin to wear away during frequent contact with food bowls and hard surfaces due to abnormal facial conformation.
In the footpads the keratin tends to accumulate on the edges of the pads, particularly in dogs with gait abnormalities due to lack of contact with hard surfaces. Fissuring and ulceration is possible in untreated cases. Corns may develop and press on interdigital areas causing pain and lameness.
Differential diagnosis
- Canine distemper. Rare but could become more common due to decline in uptake of vaccination. History of severe systemic illness prior to onset of hyperkeratosis.
- Zinc responsive dermatosis. Rare currently, suspect with dry generic diets.
- Superficialnecrolyticdermatitis. Rare. Severely ill dog with liver or pancreatic disease diagnosed by abnormal liver or pancreatic blood parameters and ultrasound examination.
- Hereditary nasal parakeratosis. Seen in young Labrador Retrievers and their crosses.
- Pemphigusfoliaceus. Usually lesions are more extensive and involve other sites – bridge of nose and pinnae, for example.
- Systemic lupus erythematosus. Rare. Multisystem disorder. Dog will be ill.
- Leishmaniasis.Historyoftravel to southern European country in Mediterranean region.
Diagnosis
- In older dogs with no other lesions and otherwise well the diagnosis can be made on clinical grounds alone. Histopathological examination will confirm the diagnosis although this is not often needed.
- Rule out diseases listed in the differential diagnosis above.
Clinical management
- Excess keratin may be trimmed prior to treatment.
- Rehydrate the skin with warm water soaks and then apply petroleum jelly once daily for 10 days. In digital hyperkeratosis cases, bandaging of the feet is advised for a few hours to avoid mess in the home. Removal of the bandages is followed by additional warm water soaks and cleaning.
- Further removal of excess keratin may be undertaken at this stage so that normal anatomical features are restored, although care should be taken not to overdo the procedure as this may provoke fissuring due to thinning of the pads.
- Where fissuring and ulceration has occurred, the above treatment can be preceded by once daily application of a steroid/antibiotic cream.
- Weekly application of petroleum jelly and trimming as required aims to prevent excessive build-up of keratin once control has been achieved.
Prognosis
The owner should be informed that idiopathic nasodigital dermatitis is a condition that can be controlled, but life-long treatment is required.
