Livestock and companion animals are valuable economically and emotionally in the economy of many states and to their citizens. In a radiological emergency situation, the loss of a large amount of livestock could be devastating to a state or national economy. If such an event occurred, there are currently no screening and decontamination protocols for the handling of livestock. This research investigated current policies and procedures for monitoring and decontamination of livestock and companion animals, as well as testing pedestrian portal monitors and a newly designed livestock portal capable of radionuclide identification. It was discovered that only ten states addressed companion animals or livestock anywhere in their emergency planning. Of the ten, only North Carolina, Washington, and a Massachusetts K9 unit had detailed decontamination procedures to report for companion animals. None of the states included detailed procedures for livestock. To address livestock screening, three pedestrian portal monitoring systems were tested in the field and lab trials – the Johnson AM801, TSA TPM903A, and Ludlum 52-1-1. The systems were tested for position and count rate sensitivity with 1 and 5 µCi 137Cs sources placed on four locations on a steer. Factors such as operability and ease of use were also considered. All three systems would alarm when a 5 µCi 137Cs source was used and the occupancy sensor was triggered. The Johnson AM801 system was determined to be the most appropriate for use in livestock screening due to sensitive alarm algorithms, greater position discrimination with four detectors, and ease of adjustment for agricultural purposes. The last phase of this project included designing and constructing a portal system that included radionuclide identification capabilities. An array of six sodium iodide detectors was mounted on a panel and field-tested beside a cattle chute and in a walkway. The custom portal, the Bovine Screening Portal (BSP), observed increased count rates (>10σ) from a 5 µCi 137Cs source in live time. The BSP demonstrated better detection and localization of the source and spectral identification capabilities compared to the commercially available pedestrian systems.