Vasculitis

34 Vasculitis




INITIAL PRESENTATION


Severe ulceration over the caudal dorsal trunk.



INTRODUCTION


Vasculitis is an uncommon to rare cause of ulcerative skin disease in the dog. Direct inflammation of blood vessels, blood vessel damage and subsequent infarction results in a loss of blood supply to, and necrosis of, dependent tissues. The clinical presentation varies widely depending on the type, size and site of vessel involved. This report describes a case of vasculitis in a dog involving large dermal vessels resulting in severe cutaneous lesions. There was evidence in this case that a drug eruption may have triggered the disease.




CASE PRESENTING SIGNS


A 9-year-old, neutered male rough collie was presented because of severe ulceration over the caudal dorsal trunk.



CASE HISTORY


Vasculitis is not a specific diagnosis, but is usually a manifestation of some underlying disease process. There are many potential causes and this may be reflected in the history. As has been stated before in this book, a detailed history is essential to improve the chances of identifying and correcting the underlying cause.


The history in this case was as follows:


• The patient was initially presented for a dermatology referral with a 2-month history of full-thickness cutaneous ulcerations over the caudal dorsum and erythematous scaling lesions over the ventral trunk.

• Three months earlier, the dog had been presented for veterinary examination because of an inability to stand. Pyrexia (105°F) and lumbar pain had been evident on physical examination and discospondylitis was diagnosed on radiography. The dog was treated with a combination of carprofen and a 4-week course of cefalexin.

• A few days prior to completion of the initial course of cefalexin, the dog started to develop ventral skin lesions. The onset had been rapid, with development of large ulcerated areas of skin over a period of a few days.

• The skin lesions had been painful.

• Subsequent treatment with antibiotics, glucocorticoids and non-steroidal anti-inflammatory drugs had resulted in no clinical improvement in the appearance of the skin.

• There had been evidence of polyuria and polydipsia. This was probably associated with glucocorticoid administration as these symptoms were resolving with withdrawal of treatment.

• The dog had lost a moderate amount of weight since the onset of the skin lesions.

• There were no other animals in the house. There was no history suggestive of zoonosis and the dog had never been out of the UK.

• The diet consisted of a tinned dog food and biscuit mixer with additional scraps, with milk and water to drink.


CLINICAL EXAMINATION


Vasculitis can be associated with a wide variety of clinical signs. Damage to dermal and mucosal vessels results in leakage of contents and infarction. The signs of cutaneous vasculitis reflect this, and include petechiation, ecchymoses, purpura, subcutaneous oedema, scaling, alopecia, erosions, ulceration, necrosis and scarring. There may be substantial areas of necrotic tissue depending on the size of vessel involved. In addition, there are vasculitis syndromes in man and domestic animals involving vasculature of internal organs, and therefore many different systemic clinical signs can arise depending on the organ(s) involved. Clinical signs may also reflect an underlying disease process such as a connective tissue disease, infection or neoplasia. Systemic signs can include fever, anorexia, glomerulonephritis, polyarthropathies, myopathies, retinitis, uveitis, neuropathies, gastrointestinal signs, pancreatitis, epistaxis, and pleural and peritoneal effusions.


The clinical signs in this case were as follows:


• The patient was slightly obese and weighed 36 kg. Rectal temperature was 102.5°F and pulse rate was 136 bpm. Detectable abnormalities were otherwise confined to the skin.

• There were extensive, full-thickness, punched-out ulcerations with a symmetrical distribution over the caudal dorsum, with malodorous, necrotic debris within the ulcerated areas (Figs 34.1 and 34.2). In addition, there were coalescing, erythematous and scaling macules, patches and plaques over much of the ventrum, extending from the neck to the groin region (Fig. 34.3).

image

Figure 34.1 Cutaneous vasculitis at initial presentation. Full-thickness, punched-out ulcers with granulation are apparent over the caudal dorsum.


image

Figure 34.2 Cutaneous vasculitis at initial presentation. Full-thickness, punched-out ulcers with granulation can be seen over the caudal dorsum.


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Figure 34.3 Cutaneous vasculitis at initial presentation. Erythematous and scaling macules and patches over the ventral trunk are apparent.




DIFFERENTIAL DIAGNOSES


The multifocal, full-thickness, punched-out ulceration was suggestive of a vasculitis or vasculopathy, but other possible differentials included:


• Deep pyoderma

• Other atypical bacterial infections

• Deep fungal infection

• Demodicosis

• Sterile panniculitis

• Vasculitis/vasculopathy

• Bullous pemphigoid

• Pemphigus vulgaris

• Erythema multiforme/Stevens–Johnson syndrome/toxic epidermal necrolysis

• Systemic lupus erythematosus

• Drug eruption

• Cutaneous T-cell lymphoma.


CASE WORK-UP


The skin lesions were severe to the point of being life threatening and an aggressive diagnostic approach was indicated. In addition to ruling out demodicosis and performing routine cytology, it was necessary to try and identify a possible underlying cause, including identification of any potential systemic involvement.


The following diagnostic tests were performed:


• Multiple deep skin scrapings, which were negative for Demodex mites.

• Cytological examination of smears from ulcerated areas, which showed degenerate neutrophils, activated macrophages, many cocci and a few rods.

• Routine haematological and biochemical examinations, which showed mild anaemia, thrombocytopenia (76 × 109/l), mild neutrophilia, lymphopenia, hypoalbuminaemia (18.5 g/l; normal reference range 26–35 g/l) and hyperglobulinaemia. Alkaline phosphatase was moderately elevated (178 IU/l; normal reference range 38–108 IU/l). Antinuclear antibody titre was <1/8, well within the normal laboratory reference range.

• Urinalysis (collected by cystocentesis), which showed a specific gravity of 1.013 and a trace of haemolysed blood but was otherwise unremarkable.

• No abnormalities were detected on survey chest and abdominal radiographs.

• Skin biopsies were harvested and submitted for histopathological examination. Samples were taken from the ventral exfoliative lesions (8-mm biopsy punch), as well as the margins of ulcerated areas (excised using a scalpel). Histopathological examination showed varying changes, including vasculitis, panniculitis and diffuse granulomatous inflammation. It was considered that some, or possibly all, of the erosion and ulceration was ischaemic and due to vasculitis.

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Sep 3, 2016 | Posted by in SMALL ANIMAL | Comments Off on Vasculitis

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