My corgi is almost 2, and was the only dog until 4 months ago when my sister’s dog moved in (6 year old American staffie who is a sweet lap dog).

They have been getting along fine - there’s been the occasional getting to rough and fighty but nothing to cause concern. And yes, the corgi has been more of the bully than the bully breed. 

The past week my corgi has been displaying some new aggression. Couple events that stick out:
- they both had lick mats in the same room but opposite ends - they do this thing where they swap food bowls/lick mats, and they did this but my corgi decided to go back to his and got snarly and showed teeth. In the past this wasn’t an issue
- when protecting us from the evil delivery drivers, my corgi will sometimes get super aggressive with barking and will nip at my sister dog. I’ve started getting him to touch my hand to calm down, and for the most part has subsided the hostile aggression. 

They are fed in separate bowls that are next to each other and have shown no issues with eating as much as they want and have shared bowls in the past. When it comes to treats, they are each given equal treats at the same time. Occasionally, they get a tough chew that we do monitor cause they both have gotten a little protective but that is expected. 

To my fellow lowrider care takers:
- is this resource guarding? First corgi and dog who’s exhibited this behavior 
- how did you handle training in a multi dog household?
- the internet says I should see a vet, is there a condition or something that could bring this on?
- any word of advice or encouragement dealing with my stubborn sassy monster?

Starting to resource guard?