I went to the vet with my dog. And I thought that my dog was the most restless dog in the waiting room of the vet. Most of the dogs were sitting on the laps of their owners, while only my dog was trying to run and jump... 聼起來自然嗎?

Yes, it sounds natural. A little more natural—
I took my dog to the vet, and it seemed to me that my dog was the most restless dog in the vet’s waiting room. Most of the dogs were sitting calmly on the laps of their owners, but my dog was trying to run and jump.