Approach to diseases of the nasal planum and footpads (Proceedings)

Diseases of the nasal planum and footpads in cats and dogs range from life threatening diseases to benign conditions that require long-term therapy to maintain control. It is of the utmost importance to properly diagnose the diseases that affect these locations, as the treatment and prognosis varies greatly depending on the disease entity. It cannot be underestimated how valuable histopathology is in elucidating the majority of these diseases.

History

Taking a thorough history is the first step in determining the underlying cause of diseases of the nasal planum or footpads. Age of onset, breed, gender, location of lesions, systemic illness, spread to other animals/humans, husbandry conditions and chronicity/progression of disease all give clues to narrow down the differential list. For example, if a cat with a history of chronic upper respiratory tract infections starts developing ulceration of the nasal planum, feline herpesvirus dermatitis would be a top differential.

Physical Examination

A complete physical examination is key. It is especially important when evaluating diseases of the paws to differentiate between diseases of the footpads versus interdigital pathology, as both can cause lameness and pain. Furthermore, the presence of lesions on locations other than the nasal planum and footpads needs to be noted, as this will affect the differential list. In addition, the lesion type should be determined to help assist with the differential diagnoses list.

Differential Diagnoses

Tables 1 and 2 present the most significant diseases affecting the nasal planum and footpads of cats and dogs, as well as other key points about the diseases.

Table 1. Differential Diagnoses For Diseases Affecting The Nasal Planum And Footpads In Cats

Diagnostic Tests

      Cytology/Skin scraping

Cytology can be very helpful in cases involving the nasal planum and footpad to evaluate for things such as bacteria, acantholytic keratinocytes associated with pemphigus, and inflammatory cells that can give clues to the underlying etiology. Skin scraping can also be useful in certain cases to evaluate for parasitic causes of disease.

Table 2. Differential Diagnoses For Diseases Affecting The Nasal Planum And Footpads In Dogs

           Fungal Culture

Fungal culture should be performed to rule out dermatophytosis. In cases where acantholytic cells are seen on cytology and pemphigus is suspected, a fungal culture should definitely be performed as inflammatory, pustular dermatophytosis can cause acantholysis.

           Skin biopsy

Definitive diagnosis of the majority of the diseases of the nasal planum and footpads are confirmed by histopathology. It is imperative that the clinician be comfortable choosing lesional skin, as this is the most likely to provide a definitive diagnosis. In general, ulcerated skin should be avoided, as the epidermis is no longer intact. As bacteria and/or yeast often colonize compromised skin, treatment with antimicrobials is usually indicated prior to taking biopsies. Furthermore, as diseases of these anatomical locations are often unusual, it is also recommended that biopsy samples be sent to a dermatopathologist or a pathologist with a special interest in skin disease, as the changes in some of these conditions can be subtle and require an experienced eye to diagnose.