Vet360 Vol 3 Issue 04 August 2016 - Page 36

DERMATOLOGY NECROLYTIC MIGRATORY ERYTHEMA (NME) aka Superficial Necrolytic Dermatitis, Hepatocutaneous Syndrome, Metabolic Dermatosis, Metabolic Epidermal Necrolysis: NME is a rare, ulcerative, crusting condition that affects the mucocutaneous junctions (muzzle, lips, nose, eyelids, anus, genitalia) and pressure points (elbows, feet). Hyperkeratosis and fissuring of the foot pads commonly occurs. All foot pads are usually involved and the interdigital spaces and nail folds are also typically inflamed and crusted. The paws often become very painful resulting in lameness and reluctance to walk. Secondary infections with bacteria, fungi or yeasts are common. The disease is generally seen in middle aged to older dogs and may wax and wane. Foot pad and skin lesions are common early manifestations of this condition and precede or accompany chronic liver disease (e.g. cirrhosis, druginduced hepatitis (phenobarbital) and chronic active hepatitis) or very rarely glucagon-secreting pancreatic tumours (glucagonomas). The lesions are thought to be manifestations of nutritional abnormalities related to amino acids, essential fatty acids or zinc. Systemic signs usually occur later and may include weight loss, lethargy, anorexia, icterus, polyuria and polydipsia. Concurrent diabetes mellitus is relatively common (especially later in the course of the disease). Histopathologic findings of skin biopsies are classic and highly characteristic. These include a superficial perivascular to lichenoid dermatitis, parakeratotic hyperkeratosis, and a marked intra- and intercellular oedema limited to the upper half of the dermis. These histologic findings appear as a red, white and blue colouring band within epidermis. Once a diagnosis of NME has been made, hepatic ultrasonography should be performed. Hepatic ultrasound usually reveals a hyperechoic network surrounding hypoechoic areas of parenchyma, likened to a Swiss-cheese or honeycomb appearance. This pattern is considered pathognomonic in the dog for NME. There is no effective treatment and the prognosis is guarded. Corticosteroids should not be used as many of these patients are diabetic or prediabetic. Temporary improvement may be achieved with nutritional support. Amino acid supplementation either with intravenous amino acid preparations or with oral supplementation e.g. egg yolks (1 egg yolk per 5 kg body mass), essential fatty acids and zinc can be given. A low fibre, highly digestible diet is recommended. Treatment of the underlying liver disease would be the best option. Drugs such as colchicine and milk thistle are often used. Where a glucagonoma can be surgically removed, the skin lesions start to resolve a week after surgery and completely resolve within 45 days. Necrolytic migratory erythema of the footpads (http:// www.dermatologyforanimals. com/faq-38/) ZINC RESPONSIVE DERMATOSIS: Zinc is very important in ensuring epithelial tissue integrity. Any qualitative or quantitative deficiency in zinc, may therefore cause skin problems. Two types of zinc responsive dermatosis have been described. Type 1 is a syndrome that has been described in young dogs. It is considered to be a genodermatosis involving a defect in intestinal zinc absorption and possibly zinc metabolism at cellular level. Nordic breeds are predisposed with 75% of cases reported in Siberian Huskies. The age of onset is usually between 6 months and 3 years. This condition mainly affects the face (lips, ear pinnae, bridge of the nose, periorbital area), foot pads and perianal region. Typical skin lesions include erythema, scaling and crusting of all affected areas. Systemic signs, such as pyrexia, are common. Diagnosis is based on history, lesion distribution and histopathology of skin biopsies. Prognosis is good, but recurrences are common. Treatment typically consists of zinc therapy (zinc methionine), low dose prednisolone to help intestinal zinc absorption, antibiotics in cases of secondary bacterial infections and keratomodulating shampoos for the skin lesions. Type 2 is a syndrome seen in large breed puppies on poorly balanced diets (excessive cereal, phytate or calcium) or in adult dogs with intestinal malabsorption. Dermatological signs are identical to those seen with type 1 and systemic signs, in particular pyrexia, are common. Diagnosis is based on history, clinical signs and histopathology of skin biopsies. The prognosis is excellent in general. Zinc should be given in conjunction with a balanced diet for 3 to 4 weeks and can then be stopped. In cases of malabsorption the supplementation may be lifelong unless the cause of the malabsorption can be diagnosed and treated successfully. A: Zn-responsive dermatitis affecting the feet and elbow (http://dermvettacoma.com/zinc-responsive-dermatosis/) B: Zn-responsive dermatitis affecting footpads (http://www.siberianhuskyhealthfoundation.com/images/Untitled-1.jpg) FOOT PAD FOREIGN BODIES: Foot pad foreign bodies are very common and easily missed. The entry wound may be very small and the foreign body not visible to the naked eye. Glass and other sharp hard objects are usually the cause. Well localised discomfort is usually present and the patient often presents with lameness. The treatment is general anaesthetic and surgical excision or removal. vet360 Issue 04 | AUGUST 2016 | 36 VET360 AUGUST 2016 working.indd 36 2016/07/25 11:04 PM