Ask your vet to check his blood protein levels: malnutrition or protein loss can lead to fluid in the abdomen.

Normally, the blood protein haptoglobin binds circulating myoglobin and other heme-containing substances, but in rhabdomyolysis the quantity of myoglobin exceeds the binding capacity of haptoglobin.

Swelling occurs due to kidney failure, combined with the loss of blood protein.

Some studies implicate the interactions between a common blood protein (albumin) and astrocytes.

They identified a number of common features, but not blood protein abnormalities or elevation of the rate of erythrocyte sedimentation.