Objective: To evaluate the association of admission total plasma protein (TPP) and the administration of red blood cell transfusions in dogs with diagnosed hemoabdomen. To secondarily evaluate additional point‐of‐care parameters associated with red blood cell transfusion administration. Design: Retrospective study between 2009 and 2019. Setting: University veterinary teaching hospital. Animals: Ninety dogs admitted to a university veterinary teaching hospital after a diagnosis of traumatic or nontraumatic hemoabdomen (NTH). Measurements and Main Results: Medical records were retrospectively reviewed; signalment, point‐of‐care diagnostics, and transfusion administration information was recorded. A total of 47 dogs (traumatic hemoabdomen 11/26; NTH 36/64) received packed red blood cell transfusions. For each 1 g/dL unit decrease in TPP, dogs had an increased odds ratio (OR) of 2.14 (95% confidence interval [CI]: 1.44–3.40, P < 0.001) of receiving a red blood cell transfusion. Dogs diagnosed with NTH were more likely to receive a red blood cell transfusion than dogs with a traumatic hemoabdomen (OR: 2.78, 95% CI: 1.11–7.141, P = 0.03). Lower PCV values (OR: 1.08, 95% CI: 1.04–1.12, P < 0.001), bicarbonate values (OR: 1.3, 95% CI: 1.09–1.56, P = 0.003), and base excess (OR: 1.27, 95% CI: 1.1–1.49, P = 0.003) were associated with a higher likelihood of red blood cell transfusion. Additionally, higher lactate (OR: 1.35, 95% CI: 1.16–1.63, P < 0.001) and Acute Patient Physiologic and Laboratory Evaluation (APPLE)fast scores (OR: 1.10, 95% CI: 1.04–1.17, P < 0.001) were associated with increased red blood cell transfusion administration. Conclusions: Low admission TPP, independent of low PCV, was associated with red blood cell transfusions regardless of underlying cause. For each 1 g/dL unit decrease in TPP on presentation, dogs were approximately 2 times more likely to receive a red blood cell transfusion during hospitalization. Other factors that were associated with increased transfusion administration included presenting PCV, PCV/TPP ratio, bicarbonate, base excess, lactate, and APPLEfast scores. [ABSTRACT FROM AUTHOR]