Dealing with blocked veins

Whenever an injection is given, it carries a minute risk of causing an infection or a localised reaction. Harry, a six-year-old Thoroughbred hunter, had been with his present owners for six months when they noticed a soft, painless swelling below his left ear, which appeared temporarily while he was grazing.

Further examination revealed a slightly thickened, or “corded”, left jugular vein. We surmised that Harry had, in the past, reacted to an intravenous injection, resulting in a thickening of the jugular’s walls and a reduction in the size of the area that blood flows through (the lumen). Bloodflow back from the head to the heart on this side was therefore compromised, producing a temporary swelling (or oedema) below the ear when gravity was an additional factor. Harry appeared unaffected by all this at first, but by the autumn the oedema was increasing and the jugular vein was thickening and becoming tender.