Snoop Dogg isn't the only canine with a nose for weed ... TMZ has learned the rapper was arrested in Texas this weekend after a drug-sniffing dog uncovered marijuana on his tour bus.
Law enforcement sources tell us ... Snoop's tour bus was stopped at a border patrol checkpoint in Sierra Blanca -- a small town in West Texas where Willie Nelson was popped for weed back in 2010.
We're told the border patrol ran a standard inspection of the bus with the dog ... when the animal alerted the agents to a possible hit in a waste basket in the back of the vehicle.
The agents claim they found a red prescription bottle with several joints inside. We're told the bottle contained under a half-ounce of weed.
Cops say Snoop admitted the dope belonged to him. Snoop has a prescription for cannabis in California, but law enforcement tells us, there is a zero tolerance policy for weed in Texas ... regardless of his status in other states.
Snoop was issued a citation for misdemeanor drug possession and released. If convicted on the drug charge, Snoop could face up to 180 days in jail.
Attempts to reach the rapper's rep were unsuccessful.
The war on drugs is complete bullshit....