The secuirty was limited when i was there. Infact i didnt see any actual "security guards", just train conductors. Occasionally state customs will come on the train with dogs, especially on long journeys. Obviously theres always a risk but aslong as your not transporting a smelly shit load you should be alright. Wrap it in a lot of clothes in your bag or put it in an air tight box.

When i was there i met someone who befriended some of the kitchen staff and hid theirs in the kitchen becuase no dogs are allowed in there.

Hope thats helped