DERMATOLOGY
CANINE PAPILLOMA VIRUS : Papilloma viruses ( Papovavirus family ) exhibit a marked tropism for squamous epithelium , are species specific and potentially contagious . This virus can cause a variety of clinical entities in dogs from warts in the oral cavity and on the skin , cutaneous horns on the foot pads to cutaneous inverted papillomas . Diagnosis is made clinically due to the characteristic lesions but may be confirmed by histopathology . There is no specific treatment . Many virus induced lesions may regress spontaneously after a few months . Treatment that may be attempted for papilloma virus infections include interferon and a vaccine created from surgically excised tissue .
VITILIGO : Vitiligo is a condition associated with an acquired loss of pigment in the skin due to selective melanocyte destruction . The pathogenesis is not clear but an auto-immune mechanism is most likely . Vitiligo is sometimes associated with other auto-immune conditions such as juvenile diabetes mellitus . Dermatological signs include achromic macules at mucocutaneous junctions ( nose , eyelids , lips and anus ) and depigmentation ( without inflammation ) of the foot pads , nails and coat .
Diagnosis is usually made on clinical findings with or without histopathology . Histopathology shows relatively normal skin which is devoid of melanocytes . There is no specific treatment as the condition is merely cosmetic . Topical 0.1 % tacrolimus has occasional success . Spontaneous remission sometimes occurs .
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A : Canine papilloma virus ( http :// www . askavetquestion . com / answer _ np . php ? id = 4717-wart-on-dogs-foot ) B : Canine papilloma virus ( http :// www . allwidewallpapers . com / extra-pad-on-dogs-paw / ZXh0cmEtcGFkLW9uL- WRvZ3MtcGF3 /
Papilloma viruses have also been implicated as one of the causes of a condition called Canine Foot Pad Papilloma . This condition has primarily been reported in active and retired racing Greyhounds but may affect any breed . The foot pad lesions are firm , well demarcated , circumscribed hyperkeratotic lesions that have a central core of keratin which is often conical . The gross appearance is that of scar tissue . These lesions cause pain and local inflammation and have been called corns . Corns can appear on multiple foot pads and cause lameness . Other proposed causes are foreign bodies and repetitive mechanical trauma from pressure and abrasions .
Corn in foot pad ( From : Fawcett A , Phillips A . 2012 . Clinical snapshot : A Corn in a Whippet . Compendium for continuing education ; September 2012 : 34 : 9 )
ICHTHYOSIS : Ichthyosis is a congenital disorder resulting from a defect in one or more steps of stratum corneum differentiation . Epidermolytic and non-epidermolytic forms have been described .
Breed specific forms have been identified . Breeds affected include Golden and Labrador retrievers , Cairn and Norfolk terriers , Jack Russell terriers , Rottweilers and American bulldogs .
Dermatological signs vary with the form and breed affected and vary from a mild exfoliative dermatosis to generalised thick , large scales adherent to the skin . Foot pad involvement does not occur in all cases , but where it does , it is characterised by extreme hyperkeratosis and exaggerated thickening of the digital , carpal and tarsal foot pads . Severe cases usually present at the age of 2 months , but milder cases may only present in young adulthood .
Diagnosis is made by histopathology of skin biopsies . Treatment is symptomatic and includes moisturising agents , keratomodulating shampoos to correct excessive scale production and improve skin hydration and essential fatty acid supplementation to limit water loss .
PRACTICAL TIPS
• In a generalised skin condition , where the foot pads are also affected , take samples and biopsies from areas other than the footpads , where possible .
• Foot pad wounds bleed profusely and can be slow to heal .
• It is easy to miss representative lesions when taking biopsies of foot pads .
• Histopathological interpretation of foot pad skin is challenging .
• Foreign bodies should be ruled out as a cause at an early stage , especially in patients who present with lameness and where only one foot pad is affected .
• Consider pain management in all cases .
• Aggressive medical treatment is frequently required .
• Topical treatments will always be a beneficial adjunctive therapy , also useful palliatively .
• Foot coverings will help to protect the foot and increase contact time of topical treatments .
• Review diagnosis in cases of poor response to treatment .
References available on www . vet360 . vetlink . co . za Shaping the future of animal health vet360
Issue 04 | AUGUST 2016 | 38