hi, im sorry about your little guy! i know what youre going through. my pup is finally recovering from HOD. yes, it will cause the legs to swell, in front or in back, or both. Chloes hocks and knees used to get really bad. try wrapping them in cold packs to reduce some of the swelling. it wont take it all away, but it will help. i know how the relapses are... it was like Chloe would relapse EVERY SINGLE SUNDAY, it was tough. the temp is really something thats most important to watch. thats really the part that if a pup dies from HOD, its the usual culprit. along with dehydration. if the temp gets too high (104-106) a cool shower will help. but do call your vet if it gets to 106. they might want you to bring him in then. i hope this doesnt last too long for you! Chloes lasted about 3 months, but shes running and playing and everything now. its tough but hang in there!!!