Cutaneous manifestations of systemic disease

01 March 2013, at 12:00am

JAYNE LAYCOCK reports on her ‘pick of the month’ CPD webinar presented by Professor Stephen White of the department of medicine and epidemiology at the University of California, Davis

THE cutaneous manifestations of systemic disease with Professor Stephen White was a great way to end a memorable year of CPD webinars by The Webinar Vet.

Professor White presented a number of cases which fall into this curious category in both cats and dogs, and gave useful advice on how to best manage these challenging cases.

The feline perspective

Feline paraneoplastic alopecia was the first condition discussed by Professor White and is mostly seen in older cats with a rapid onset of clinical signs. Cases present with ventral abdominal alopecia, glistening skin and dry, fissured peeling footpads.

These cats may suffer with pruritus, excessive grooming, and tender feet leading to an unwillingness to use litter trays. Some of these cases may also have secondary Malassezia and Professor White was keen to stress that if cats present with generalised Malassezia, more serious underlying disease such as feline paraneoplastic syndrome, cutaneous lymphoma or pemphigus foliaceous should always be considered.

The underlying condition, an exocrine pancreatic adenocarcinoma, is an aggressive tumour which, at the point of diagnosis, has more often than not already metastasised to the liver and lungs. Skin biopsies reveal severe atrophy and miniaturisation of the hair follicles from which a diagnosis can be made.

These cases have a poor prognosis despite there being a small number of reports in literature stating that removal of the pancreatic tumour can provide temporary symptomatic relief. Unfortunately, clinical signs tend to return within 2-3 months due to metastasis for which there is no known therapy. 

Exfoliative dermatitis with thymoma is another condition seen in older cats which present with non- pruritic erythematous scaling to the head sometimes affecting the rest of the body. These cases are very exfoliative and may also be suffering from generalised Malassezia which can often lead to the presence of crusts.

Histopathology on skin biopsies will reveal erythema multiforme and although this may be seen in a number of conditions, it is most commonly seen secondary to a tumour or medications. A chest x-ray will confirm the presence of a thoracic mass and surgical excision of the associated thymoma should lead to the resolution of all clinical signs.

Metastatic pulmonary carcinoma is a condition seen in cats where there has been metastasis from a form of lung tumour to the feet, with the front paws most likely to be affected.

The clinical signs are dramatic with swelling and ulceration to the digits and x-rays reveal almost complete decimation to P3. The lung tumour is confirmed by performing a chest x-ray.

The canine perspective

Superficial necrolytic dermatitis otherwise known as “hepatocutaneous syndrome” is seen in older dogs. Professor White has a theory that the greater the number of names we have for a condition, the less we are likely to know about it, giving an indication of how challenging these cases are likely to be.

We don’t know what the underlying cause is for this particular condition but generally it does seem to be associated with very low serum amino acid levels. Also, at least 20% of dogs with this syndrome suffer from diabetes mellitus and 5% of dogs will have a glucagonoma.

These cases present with clinical signs mimicking autoimmune dermatological disease. Crusts, fissures and ulcers present at mucocutaneous junctions and on footpads, with some dogs showing only lameness at initial presentation due to the footpad lesions. However, unlike the classical presentation of autoimmune disease, the nasal planum usually is not affected.

Any breed can get this disease but there are certain breeds which have a predilection, such as the Sheltie and Border Collie.

Skin biopsies and ultrasound should be performed to try and make a diagnosis. Histopathology on the skin will show parakeratosis with a high level epidermal oedema and an abdominal ultrasound will reveal a “Swiss cheese”-like liver. A glucagonoma may also be seen on ultrasound.

Unfortunately, these cases have a poor prognosis and 50% of patients will be euthanased within two months of diagnosis. However, treatment isn’t always hopeless and the use of intravenous amino acids can be administered over 2-3 days whilst hospitalised.

Despite being expensive, this treatment can make a real difference to the demeanour of some cases and if effective should be performed every 3- 6 weeks.

Oral products using protein supplementation with raw egg yolks (3- 6/day), elemental Zn (2mg/kg/day) or whey protein (1-2 teaspoons/5kg) can sometimes help although the success rate is not as high. If a dog is lucky enough to fall into the 5% of cases that have a glucagonoma, then surgical excision of this tumour should resolve clinical signs.

Nodular dermatofibrosis syndrome is a condition seen primarily in middle-aged German Shepherds. They present with pitted nodules, most commonly found on distal extremities, and are consistently associated with renal cysts, cystadenocarcinomas or malignant adenocarcinomas. Diagnosis is made by performing skin biopsies and ultrasound of the kidneys.

The formation of renal cysts is inevitable and will eventually present on both kidneys, making the removal of one kidney futile. Prof. White advised that if cysts aren’t found on ultrasound initially, it is always worth checking again in six months. These renal cysts are usually slow growing and dogs tend to compensate well and can survive for five years and more assuming these cysts are benign.

The speaker did discuss a number of other conditions which fall into this category including sertoli cell tumours, hyperadrenocorticism and hypothyroidism.

The diseases highlighted in this article were conditions I perceived we are less familiar with and I would highly recommend logging into this webinar available through The Webinar Vet. Like me you may find some light is shed on those mystery skin cases that seem impossible to solve.