Can a rattlesnake bite make my dog's spleen swell or enlarge?

Hi and thanks for using Petco Pet Education Center, formerly Petcoach! Sorry to hear about Rocks. I would think that since the spleen plays a big role in the immune system and a storage area for red blood cells, that a subsequent enlargement of the organ is entirely possible. I would say this though......if the spleen remains enlarged a month or two after the snake bite episode, I would pursue the x-ray and/or ultrasound to evaluate why it is truly enlarged. Many middle aged to older dogs end up having problems with their spleens including hematomas, splenic cysts, or even splenic tumors which can either be benign or malignant. Sometimes these problems with the spleen cause internal bleeding from the damaged organ thus often necessitating an emergency splenectomy. Your vet is correct to advise imaging studies to try to detect an enlarged spleen and attempt to treat it if necessary in a non emergent setting. Good luck with Rocks and I hope this is all related to the snake bite.