Captain reported conducting a go around while on an ILS approach after spotting a truck on the landing runway. After coordinating with ATC; the flight returned for an uneventful landing.

Narrative

While executing an ILS approach to 18R. We were cleared for the approach to 18R by Houston Center. Houston Center then handed us off to Laredo Tower; were Laredo tower cleared us to land 18R. The visibility was marginal with 5 SM and haze reported on the ATIS. Approaching short final; I (PF) noticed a vehicle on the runway within the touchdown zone. I queried my crew and they noticed the same obstruction. The First Officer (PM) said to the tower. 'There is a truck on the runway'. By the time Laredo tower issued a go around; I was in the process of executing a go around procedure. Laredo tower then gave us climb out instructions and asked our intentions. We requested another approach into runway 18R. Laredo Tower told us to contact departure. Houston Center asked what was the reason for the missed approach? We advised them that there was a truck on the runway. Houston Center then proceeded to give us vectors for the 18R approach. We received vectors for the approach; was cleared for 18R approach and was handed off back to Laredo tower. Were Laredo tower cleared us to land. We landed with no consequences and taxied to parking.