Answer:
Ibn Sina's book played the role of being the only respectable book used in the teaching of medicine in the universities of the Middle Ages, both in the dominated by the Arab-Islamic empire Europe and in the nearby Western countries.
It should be noted that the Canon of Medicine (along with the Book of Healing), was made up of several systematically ordered volumes and was written by the Persian Muslim doctor Ibn Sina ("Son of Sina" this is how he was called in abbreviated form). His work was very well accepted at that time until the Renaissance, for its scientific and encyclopedic character and for integrating the Arab philosophy with the Greek philosophy that was accepted at that time.
In fact, the book succeed in displacing the works of the Greek physician Galen and it became the preferred manual for European medical schools.
This book gave many contributions to medieval medicine, among which stand out the knowledge of the the human eye antomy and the recognition of the symptoms of diseases such as diabetes and meningitis. In addition to daring to affirm that the rats could be a determining factor in the transmission of the plague, which was confirmed years later with the black plague that invaded Europe.