Approach to pedal dx

What are the features of sterile pyograulomatous pododermatitis?

• Interdigital folliculitis/furunculosis

• +/- interdigital cysts or nodules

What causes sterile pyogranulomatous pododermatitis and what breed are predisposed?

• Trauma from the environment (can have self induced - atopic dermatitis)

• Weight bearing, particularly in heavy dogs, may be distributed to haired interdigital skin adjacent to paw pads

• Most commonly in smooth, short-coated breeds - English bulldogs, Staffies and Labradors

Where would the pododermatitis be located if it is due to trauma?

• Front feet take more weight and are more prone to trauma

• Usually between digits 3 and 4, and 4 and 5

Which animals are more likely to have issues with weight bearing?

• Flat foot and scoop-shaped web of some breeds

• Wide-based paws i.e., more distance between pads

• Orthopaedic problem

Describe how weight bearing causes pododermatitis to occur?

• Friction + pressure → hair follicle damage → keratin release

• Triggers inflammation (foreign body reaction)

• May involve external debris (e.g. gravel)

• Starts sterile, but often becomes infected

• Repeated trauma → scarring and chronic disease

Describe the lesion associated with Sterile pyogranulomatous pododermatitis?

• Lesions form on ventral interdigital surface, but rupture onto dorsal surfaces

• Erythema, oedema, comedones, nodules, pustules, ulcers, haemorrhagic bullae, haemorrhagic draining tracts, pyogranulomas and callus formation

• Scar tissue from recurrent episodes

Describe what is being shown here

• Dorsal interdigital space

  • Haemorrhagic nodule (red arrow) about to rupture

    • also, erythema, oedema, alopecia

• Ventral corresponding surface

  • Erythema, alopecia, lichenification, comedones (purple arrow), pocket (white) and callus (green)

    • from lesion rubbing on adjacent skin

  (sterile pyogranulomatous pododermatitis)

How would you treat pedal disease caused by atopic dermatitis?

Ciclosporin and topical steroid spray

How would you have to treat pedal disease due to orthopaedic issues or abnormal conformation of legs?

• Can start with ciclosporin and topical steroid cream

• Would have to consider surgery

What is being shown here?

• Conforming pads (pink circle)

• Sterile pyogranuloma (green) and comedone formation (yellow)

What is being shown here?

Expression of follicular contents (arrowheads) caused by pressure from the dorsal surface

What are the ddx for sterile pyogranulomatous pododermatitis?

• Demodicosis

• Primary infections - atypical bacterial or fungal

What are the comorbidities for sterile pyogranulomatous pododermatitis?

• Atopic dermatitis

• Endocrine disease e.g. hypothyroidism

Why should you consider body condition score when you are investigating pedal disease?

Overweight patients are predisposed

Describe this cytology from unruptured cyst in a sterile pyogranulomatous pododermatitis?

• Neutrophils

• Macrophages (larger more blue cells)

Why may you need to biopsy rather than carry out plucks and scrapes?

Plucks and scrapes may be difficult if chronically scarred and thickened tissue

What lab test can confirm diagnosis and exclude the other ddx?

• Histopathology

• also send fresh tissue for cultures

How do you treat interdigital follicular cysts with medication?

• Treat aggressively early on to prevent scarring and perpetuation

• Immune-modulation - ciclosporin and steroids

• Topical antiseptics (particularly for chronic and draining lesions) - chlorhexidine

• Antibiotics if there is secondary infection - base on culture

How do you treat interdigital follicular cysts by altering behaviour?

(plantar comedones and large interdigital lesions)

• Restrict activity to smooth surfaces

• Protect paw from trauma (external surface and self-trauma) by using booties (measured to fit)

• Dogs with advanced disease, particularly non-responsive to medical management, benefit from surgery

  • laser or fusion podoplasty may be curative and/or improve response to medical management

What investigations would you do with this dog?

• Orthopedic examination

• Cytology and culture swabs from the sinus tracts

• Plucks and scrapes

• Baseline bloodwork

• Clip and clean

Interpret this cytology result

• Pyogranulomatous inflammation with cocci (red arrows)

• Degenerative neutrophils (pink circle); macrophage (blue circle; again, also digesting a neutrophil)

What is the characteristic presentation of feline plasma cell pododermatitis?

What other lesions may be present on the animal?

• Mainly metacarpal and metatarsal pads

• Usually, >1 pad

• Swollen pads, scaling, ulceration, haemorrhage

  • Some cats are lame

• Deep bacterial or fungal infections may rarely occur alongside PCP, especially if patient is on immune-modulatory treatment

• Some cats may have gingivitis-stomatitis and/or dorsal nasal lesions with or without pad lesions

• Some cats may have concurrent eosinophilic granuloma complex lesions

  

What species does feline PCP affect and what causes it?

• Any age, breed or sex

• Unknown aetiology (immune mediated?)

What are the ddx for feline pcp?

• Eosinophilic, bacterial, or fungal granulomas

Usually single paws:

• Neoplasia

• Inflammatory reaction to a foreign body

How do you differentiate eosinophilic granulomas from PCP?

Clinical presentation and cytology

What specific lab test would you do for diagnosis of feline pcp and what would it show?

• Fine needle aspirate cytology

• Shows plasma cells

What else should you check when investigating feline PDP?

• Check FIV status in all cats

• Suggested to check FeLV, haematology, biochemistry and urinalysis

What are the treatment options for feline PDP and what is the prognosis?

• Immune-modulatory treatment e.g., steroids, ciclosporin

• Response to therapy may be slow and relapses are possible after treatment tapered to stop

• Prognosis usually good with medical treatment

• Some cases require surgical excision of prolapsed material

  

What is feline lung-digit sydrome?

Primary lung tumours (often bronchogenic adenocarcinoma), which may be clinically silent, present because of metastatic lesions in one or more digits

What is being shown here and what is it a sign of?

• Cat paronychia - inflam around the skin of the nail/ claw

• Pemphigus foliaceus