A few years ago, my cat had to be put down because of a cancerous lump. 
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Techhunter_Talon
Soloraven13
Same
Unit One
Sorry to hear that Buffling. Diesel looks like a strong and happy doggo, tell him to fight it hard.
Daikon Ocelot
Oh, man, I can't see the picture (my country ban Imgur), well anyhow, I hope Diesel to be able to fight it. Because I believe your dog is a fighter!
SuperSkeletonboi
Ouch that hit hard for a doggo , I hope he gets better soon.
Mug Not Found
Having lost pets in the past all I can say is spend as much time with Diesel as possible, it's impossible to imagine the pain either of you must be going through, really hope he pulls through it alright.
sillybunneh
N000000oooo that is sad, why do doggos have to get sick, all dogs are good bois! I wish Diesel lots and lots of love, lots and lots of yummy snacks and get lots and lots of kisses 
Buffling you're on it rite 
Buffling you're on it rite 
Belanduraz
NOOOOOOOOOOOOOO
Buffling
Tomorrow we have to put him down
Mug Not Found
No kind god would let this happen. This can't have been easy, are you alright?