Simple SummaryDoppler ultrasonography has become increasingly available in veterinary medicine and is the gold standard method for evaluating the heart and vasculature in dogs. There is an information gap in ultrasound evaluation of the carotid arteries with respect to breed variations. This study aimed to investigate the quantitative and qualitative parameters of blood flow in the carotid arteries and to describe their correlations or associations with the breed, sex, and weight of the examined dogs. The study included eight breeds—104 dogs—and found that the highest variation in the spectral waveform and velocities of blood flow between breeds occurred in the common carotid artery. Knowledge of the physiological signs of Doppler spectral waveforms is important due to their high specificity for each evaluated vessel. Our results might help with clinical identification of pathologies based on spectral flow patterns. Every practitioner performing clinical and/or Doppler ultrasound examination of a patient should be able to distinguish physiological from pathological findings. The present study supports the hypothesis that very good reliability was obtained by pre-examination training and by following a precise methodology.AbstractNoninvasive Doppler ultrasonography (US) examination is a standard method for the clinical evaluation of the carotid arteries. Extracranial cerebral circulation includes the common carotid artery (CCA), the external carotid artery (ECA), and the extracranial part of the internal carotid artery (ICA). The present study was conducted with the objective of assessing physiological normative values and describing the appearance of spectral waveforms of extracranial arteries in 104 healthy dogs of eight breeds divided into four groups according to weight. We also focused on searching for correlations for carotid blood velocities with the resistive index (RI), body weight and diameter, and differences between observers and the influence of sex in the calculations of Doppler parameters. In the evaluated breeds, significant differences were found in the velocity of peak systolic velocity (PSV) and end diastolic velocity (EDV). There was a strong correlation between body weight and peak systolic velocity, the RI index and CCA diameter. The intra-observer agreement for the PSV and EDV parameters in each vessel was considered excellent reliability, and overall interobserver agreement showed very good reliability. This study could improve the descriptions of physiological values and waveforms recorded in carotid arteries. Defining the physiological values of velocity and the resistive index (RI) helps in the easier identification of pathology and diagnosis of disease. Our results may be used for further studies of vascular diseases in veterinary medicine that correlate with the pathology of neurological disorders of ischemic origin, further in thromboembolism, oncologic disease and degenerative, proliferative and inflammatory diseases of the arteries that lead to stenosis