MODELAGEM DA HEMODINÂMICA DE OVELHAS APÓS PERDA SANGUÍNEA

INTRODUCTION: Parasites such as Haemonchus contortus cause severe anemia in sheep, making hematocrit (Ht) a key parameter for monitoring affected animals and determining the appropriate timing for targeted selective treatment (TST). AIMS: This study aimed to monitor and mathematically model Ht recovery in sheep following acute blood loss, simulating a condition similar to that caused by the parasite, and to determine the time required for animals to reestablish initial values. MATERIALS AND METHODS: For this purpose, 450 mL of blood was experimentally withdrawn from the jugular vein of 20 sheep. The Ht was measured prior to blood withdrawal (D0), daily until D5, and subsequently on a weekly basis until D28. These data were used to develop a nonlinear regression mathematical model. The sheep were classified into five hematological profile groups according to their Ht drop and the speed of recovery. RESULTS: On average, the decline from D0 to D1 was 6%. A gradual recovery was observed, and as estimated by the model, Ht approached the initial values around day 25. By day 28, most sheep (85%) had Ht values close to their initial levels. The model accurately represented both the drop and the recovery of Ht over time and made it possible to identify distinct hematological profiles among animals. Statistical analysis revealed no association between age, weight, or body condition score and hematological classification. However, initial Ht showed a correlation with the magnitude of Ht reduction after blood loss, indicating that animals with higher initial Ht experienced greater decreases. FINAL CONSIDERATIONS: The findings demonstrate that mathematical modeling was effective in tracking and predicting Ht recovery in sheep after acute blood loss. This approach offers an innovative perspective for analyzing hematological dynamics in sheep and has potential to be useful in improving clinical monitoring of anemia and supporting decision-making regarding the optimal timing for interventions, such as TST, in the control of Haemonchus contortus.

KEYWORDS: Hematocrit; Mathematical modeling; Sheep.