What insect is this
They do resemble ticks, but we do not have clear enough photos to be sure. Are you able to re-take some pictures and attach them here? If you have a magnifying glass in the house, that may be useful in showing more detail. In most of the life stages people encounter, ticks will have eight legs and what appears to be an unsegmented body. If these are ticks, they are already engorged (filled with a blood meal) based on how rotund they are, and you should discuss options for control and possible treatment with your vet.
If you can send more photos, we'll see if we can come up with a more concrete identification.
They do appear to be ticks, though we cannot identify which species from the photos. Here is our main tick page with information, though geared towards human-tick encounters. (Incidentally, if you or anyone else was outside with this dog, or outside in the area this dog visited recently, check yourself/themselves for ticks as well. Time is of the essence in tick-borne illness transmission.)
Check with your vet at this point about having the tick(s) identified and what steps should be taken next with regards to symptom monitoring for the dog and/or any prophylactic treatments. Similarly, if you find any engorged ticks on yourself or others, query your doctor about the same.
Thank you so much for your help, I appreciate it!