We have developed and evaluated a prototype animal PET dedicated for PET/CT/RT. It consists of 12 detectors configured in a dodecagon; each panel has a 30x30 array of 1x1x20 mm3 LYSO scintillators with each end of the scintillator array optically connected to Silicon Photomultiplier (SiPM) arrays for depth-of-interaction (DOI) measurement. The trans-axial and axial field-of-view (FOV) are ~10 cm in diameter and 3.5 cm long. PCB and FPGA based detector readout and processing electronics has been developed. Preliminary system and imaging performances were evaluated with a Na-22 point source and a F-18 ultra-micro hot-rod phantom. The energy, DOI, and coincidence timing resolutions of the system are around 23%, 3.2 mm, and 4.88 ns, respectively. The measured system sensitivity is ~2.2% at the center of FOV, and the image resolution measured from the reconstructed point source images over the FOV ranges from 0.77 to 1.03 mm (mean 0.83 mm). Hot-rods with diameters from 1.0 to 2.4 mm are well separated on the reconstructed phantom image when DOI is applied.