Is my dog okay??

I have an 8 yr old blue heeler neutered male. Today we were going to pet smart and he got excited (got a red rocket is what I’m trying to say) and I noticed this big white sack on his tip…what is it and should I be concerned??

I have an 8 yr old blue heeler neutered male. Today we were going to pet smart and he got excited (got a red rocket is what I’m trying to say) and I noticed this big white sack on his tip…what is it and should I be concerned??