After a while the space is filled, but the protein can continue to draw fluid in via osmotic forces. Eventually pressure rises and vessels are compressed. Unfortunately, the vessels being compressed are the veins returning blood to the heart. Also, if the animal cannot add fluid to the body by eating, fluid in the chest accumulates at the expense of the blood volume. In effect, the blood volume is going into the chest, as if it were bleeding.
Respiration is impaired by collapse of a lung and by poor circulation.
The total effect of this profound physiologic disturbance is progressive weakness and limitation of mobility, inability to catch prey, debility and eventually death.