Trauma is a major cause of morbidity and mortality in dogs and cats. While prognostic tools are well-established in human medicine, few guidelines exist in veterinary trauma care. The Animal Trauma Triage (ATT) score and modified Glasgow Coma Scale (mGCS) are used to assess illness severity, but their clinical utility in veterinary patients remains undervalued. This study aimed to evaluate the prognostic value of ATT and mGCS scores and their association with organ dysfunction and survival in polytraumatized veterinary patients. We hypothesized that multi-organ failure (MOF) is more prevalent in non-survivors and correlates with higher ATT and lower mGCS scores. A prospective observational study was conducted for 30 patients (20 dogs and 10 cats) admitted to two veterinary hospitals. Clinical data, trauma scores, and outcomes were collected and analyzed. The overall survival rate was 83.3%; blunt trauma accounted for 80% of cases. Non-survivors (n = 5) had higher respiratory rates at admission (p = 0.01). The ATT score accurately predicted all fatalities, while the mGCS score showed limited prognostic value. MOF was the leading cause of death in 60% of non-survivors. ATT appears to be a more reliable tool for outcome prediction, enabling improved triage, resource allocation, and early intervention in veterinary trauma cases.