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.
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:
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:
Figure 34.1 Cutaneous vasculitis at initial presentation. Full-thickness, punched-out ulcers with granulation are apparent over the caudal dorsum.
Figure 34.2 Cutaneous vasculitis at initial presentation. Full-thickness, punched-out ulcers with granulation can be seen over the caudal dorsum.
Figure 34.3 Cutaneous vasculitis at initial presentation. Erythematous and scaling macules and patches over the ventral trunk are apparent.
The multifocal, full-thickness, punched-out ulceration was suggestive of a vasculitis or vasculopathy, but other possible differentials included:
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: