Vasculitis

Vasculitis – the term sounds awkward, but describes something very concrete: an inflammation of the blood vessels, which can cause considerable damage in dogs. Arteries, veins and even the smallest capillaries can be affected. When the vessel walls become inflamed, thicken or even close off, the blood no longer reaches where it is needed – and this becomes apparent in the animal sooner or later. Vasculitis can be triggered by autoimmune reactions, infections, allergies or other factors; depending on which organs are affected, the clinical picture varies considerably.

What is vasculitis?

At its core, it is an inflammation of the blood vessels – arteries, veins, capillaries. The immune system, an infection or another disorder sets a process in motion that thickens the vessel walls, promotes blood clots or, in the worst case, leads to a vessel occlusion. The consequence: tissues and organs are less well perfused. In addition, damaged vessels can become leaky, blood escapes and accumulates in the surrounding tissue – this results in bleeding and visible swelling, which is sometimes the first thing that pet owners notice in their dog.

Causes of vasculitis in dogs

Vasculitis is not a disease with a single cause. It can occur on its own or as a concomitant feature of entirely different diseases. A few of the more common triggers:

1. Autoimmune diseases: Sometimes the immune system attacks the body’s own structures – including the blood vessels themselves. This occurs particularly in dogs with systemic lupus erythematosus (SLE) or comparable autoimmune diseases.
2. Infections: Viral, bacterial, or parasitic infections can trigger vasculitis, particularly through pathogens that directly attack blood vessels. Examples of such infections include:
   • Leishmaniasis
   • Ehrlichiosis (tick-borne disease)
   • Rickettsiosis
3. Drug reactions: Some dogs develop vasculitis after certain medications – or even after vaccinations. The so-called vaccine-induced vasculitis occurs particularly after the rabies vaccine and is documented especially in Dachshunds and Shetland Sheepdogs.
4. Allergic reactions: Hypersensitivities – to food or environmental allergens – can also lead to vasculitis in rare cases if the immune system overreacts.
5. Neoplasms (cancer): Malignant tumours can activate the immune system or directly affect blood vessels, thus helping to trigger vasculitis.
6. Idiopathic vasculitis: In many cases, no clear cause is found. This is then referred to as idiopathic vasculitis – which simply means that the exact trigger remains unknown despite investigation.

Symptoms of vasculitis in dogs

What a dog with vasculitis shows depends heavily on which vessels and organs are affected. The range is wide:

Skin changes:

• The skin is often the first place where vasculitis shows itself: redness, swelling and haemorrhages under the skin (purpura) are typical. Ulcers or skin necrosis can form on the ears, paws or muzzle.
• Vasculitis in the ears often manifests as painful wounds, crusts and swelling – a picture that often alarms pet owners.

Lethargy and fever:

• Many affected dogs simply look ill: tired, weak, with elevated temperature. This is the systemic inflammatory reaction making itself known here.

Oedema:

• Leaky vessel walls allow fluid to enter the tissue. These oedemas appear preferentially on the paws, in the face or on the abdomen.

Bleeding:

• Small pinpoint haemorrhages (petechiae) or more extensive bruises (ecchymoses) can occur at various body sites and are a clear sign of vessel damage.

Pain and lameness:

• If joints or muscles are affected, the dog limps or shows pain reactions – a consequence of inflammation in the small supply vessels of these structures.

Ulcers or ulcerations:

• Chronic or severe courses can leave open wounds, particularly on the extremities or ears. These ulcers often heal slowly and are at risk of infection.

Organ involvement:

• In serious cases, the inflammatory processes spread to the kidneys, liver or heart. Then more severe complications such as kidney failure, arrhythmias or breathing problems threaten.

Diagnosis of vasculitis in dogs

Diagnosing vasculitis is not always easy because the symptoms are so varied and can mimic other diseases. As a rule, several steps are required:

1. Clinical examination: The vet carefully examines the skin, swelling and wounds. The medical history is important here – has the dog recently received a vaccination, medication or suffered from an infection?
2. Blood tests: Blood counts and chemistry profiles provide information on inflammation markers, possible infections and the general state of health. Signs of autoimmune activity can also become visible in the blood.
3. Skin biopsy: The biopsy is often the decisive step. The tissue sample taken shows under the microscope whether inflammatory changes are actually present in the vessel walls.
4. Imaging techniques: X-rays or ultrasound help to detect organ involvement or fluid accumulations that are not yet clearly evident clinically.
5. Immunological tests: If an autoimmune disease is suspected, special tests such as the antinuclear antibody test (ANA) are used.

Treatment of vasculitis in dogs

The type of treatment depends on the cause, severity and the organs affected. The aim is to curb inflammation, relieve symptoms and – if possible – eliminate the triggering factor.

1. Immunosuppressants: If an autoimmune reaction lies behind the vasculitis, prednisolone or other immunomodulators such as azathioprine or cyclosporine are frequently used. They dampen the excessive immune response and thus spare the vessel walls.
2. Antibiotics: In the case of a bacterial cause or pathogens transmitted by ticks such as Ehrlichiosis or Leishmaniasis, antibiotics are the treatment of choice.
3. Pain management: Painkillers and anti-inflammatory preparations help to maintain the animal’s quality of life while the actual treatment takes effect.
4. Topical treatments: Wounds and ulcers are treated locally with ointments or antibiotic creams to support healing and prevent secondary infections.
5. Diet management: If an allergy is the underlying cause, an elimination diet can help identify the trigger and avoid further reactions.
6. Treatment of underlying diseases: Cancer or another underlying disease must be treated in parallel – without this, vasculitis can hardly be controlled permanently.

Prognosis

How well a dog with vasculitis fares in the long term depends largely on the cause and severity. If the animal responds to treatment and the triggering factor can be controlled, the outlook is quite good. However, in severe or chronic cases, therapy may last for months or years, and without long-term control, the risk of relapse increases.

Conclusion

Vasculitis is a serious inflammation of the blood vessels that can present very differently in dogs, depending on the organ affected: from skin changes and bruises to organ problems. An accurate diagnosis is a prerequisite for effective therapy. With the right approach – whether immunosuppressants, antibiotics or a combination – the disease can be well controlled in many cases. Regular check-ups remain important, however, to detect relapses at an early stage.