"This is Us" star Justin Hartley's reeling from the loss of his dog ... but it's his second pooch he's even more concerned about.
We got Justin out in Studio City on Thursday and our guy offered his condolences after the passing of Memphis ... the 11-year-old rescue Justin and his wife, Chrishell, adopted in December 2016. Chrishell said Memphis died earlier this week after his kidneys gave out.
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Justin says it's been a tough few days but watch the vid to find out why he's also worried for his second rescue, Gracie. And for what it's worth ... he's also kinda concerned about our guy running into trees.
Our guy also wondered if it's too soon to think about getting another dog.