Diseases of The Blood Vessels

Jugular thrombosis

Jugular thrombosis is when a clot forms in the jugular vein running up the neck. This clot is usually caused by tauma to the vein and is, therefore, a complication of any intravenous injection especially catheterization.

Signs

The vein becomes thickened and there is reduced blood flow through it. In cases where there is infection within the clot the swelling is hot, painful and may have a discharging tract. If the vein is completely blocked the head region may become swollen, this will usually rectify itself as the horse is able to form an alternative blood flow around the clot.

Diagnosis

Clinical signs are usually enough for a diagnosis, however, ultrasound scanning may be used to assess the extent of the clot.

Treatment

Antibiotics and anti-inflammatory drugs are required for treatment.

Blood vessel rupture

This is the most common cause of sudden death in exercising horses and usually occurs at the pulmonary artery or aorta. The exact cause is unknown but it is possible that underlying heart disease or an aneurysm (localized dilation of a blood vessel) may predispose rupture.

Peripheral Oedema (Swellings)

Oedema is fluid just beneath the skin that accumulates and causes swellings that are cool, non-painful and pit on pressure. These swellings will usually occur ventrally i.e. the brisket, muzzle, hindlimbs and sheath most commonly affected. There are many causes and the problem should be investigated if it becomes recurrent or is alongside other clinical signs and treated accordingly.

Causes

  • Increased blood pressure – Right-sided heart failure
  • Blocked vein (e.g. jugular thrombosis)
  • Loss of proteins in blood
  • Blocked lymphatic drainage – Reduced movement (e.g. stocking up)
  • Disease of the lymphatic system (e.g. lymphosarcoma)
  • Lymphangitis / Cellulitis
  • Inflammation of the blood vessels (Vasculitis) – Allergy
  • Infection (usually viral)

Cellulitis/Lymphangitis

Both of these conditions will show a sudden hot, painful swelling of one leg often with marked lameness. There is usually evidence of a prior wound that has now become infected and the infection has spread within the soft tissues.

Treatment

Treatment is aimed at eliminating the infection using antibiotics and reducing the inflammation with anti-inflammatory drugs. Limbs can also be bandaged to help reduce the swelling and the horse allowed to move frequently.