CONDITION
Vasculitis
Vasculitis describes inflammation of blood vessels—the network of tubes that carry blood throughout the body. When vessel walls become inflamed, they can leak fluid, weaken, or narrow, affecting the tissues those vessels supply. The condition can involve vessels of any size, from the smallest capillaries in the skin to larger vessels deeper in the body, and the signs often reflect which vessels are affected. Owners most commonly notice skin changes: patches of redness, bruising, ulcers, or crusting, particularly on the ears, paws, tail tip, or other areas where skin is thinner or more exposed. Some animals develop swelling in the legs, or small raised spots that may feel firm or tender. In other cases, the first signs are less visible—lethargy, joint discomfort, or changes in appetite—because vessels in internal organs or tissues are involved. The pattern and severity vary widely, and the same outward signs can arise from many different underlying causes. This page explores what signals may point toward vasculitis, what processes can trigger inflammation in vessel walls, how the condition is investigated through examination and testing, and what approaches exist for managing it. The goal is to help you understand what vasculitis means in veterinary medicine and what shape the conversation with your vet may take.
Why this matters now
Vasculitis can appear at any age, though certain patterns tend to emerge in particular groups. Some forms occur more often in young to middle-aged animals, particularly in breeds such as Jack Russell Terriers, German Shepherds, and certain Collies, where immune-mediated processes may play a role. In other cases, the condition develops later in life, sometimes in association with infections, drug reactions, or underlying illnesses that have been present for some time. Seasonal or environmental factors—sun exposure, cold weather, insect bites—can also influence when and where signs appear.
The course varies widely between individuals and depends on which vessels are affected and what has triggered the inflammation. In some animals, signs develop gradually over weeks, with skin changes appearing slowly and spreading to new areas. In others, the onset is more rapid, with lesions emerging over days. Some cases resolve with treatment and do not recur, whilst others follow a relapsing pattern, with periods of improvement followed by flare-ups. The severity can range from mild skin involvement to more widespread effects on internal organs, and the timeline is rarely predictable at the outset.
Signals & patterns
Early signals
Reddened or purplish skin patches
Small areas of discolouration may appear on the ears, paws, tail tip, or belly, often where fur is thinner. The patches may feel warm or slightly raised, and the colour can shift from pink to deep purple depending on the degree of inflammation and whether small vessels are leaking blood into surrounding tissue.
Small crusts or scabs
Crusting often develops where the skin surface has been damaged by leaking or blocked vessels underneath. These areas may appear dry, flaky, or slightly raised, and they tend to cluster in groups rather than appearing as isolated spots.
Swelling of the paws or lower legs
Fluid can accumulate in the limbs when inflammation affects the vessels supplying them, leading to puffiness or a thickened appearance. The swelling may be symmetrical or affect one leg more than the others, and the skin over the area can feel cooler or warmer than usual.
Lethargy or reduced activity
General tiredness or reluctance to play, walk, or engage in usual routines can occur when inflammation is affecting vessels in muscles, joints, or internal organs. This sign is non-specific but often appears before more visible skin changes are noticed.
Later signals
Ulcers or open sores
When vessel damage is severe enough, the overlying skin loses its blood supply and begins to break down, forming open wounds. These ulcers are often slow to heal and may appear at the edges of earlier lesions or in new locations.
Blackened or dead tissue
In areas where blood flow has been cut off entirely, tissue can die and turn dark or black, particularly at the tips of ears, tails, or toes. This reflects complete loss of oxygen and nutrients to that part of the skin or deeper tissue.
Weight loss or reduced appetite
When inflammation involves vessels in the digestive system or other internal organs, animals may lose interest in food or fail to maintain condition. This tends to develop over time rather than appearing suddenly, and may be accompanied by other subtle changes in behaviour or energy.
Click to read about the biological mechanisms
How this is usually investigated
Options & trade-offs
Last reviewed: Invalid Date ·