The woman, who wishes to remain anonymous, argued that her dog is her family, and therefore deserved to be paid for the days she couldn't work.
The LAV is one of the biggest animal rights charities in Europe.
She adopted Cucciola, 12, after she was found abandoned in a Rome park and took two days off to look after her as she recovered from surgery for a breast tumour and a larynx problem.
The woman asked the university to grant her paid leave in order to take Cucciola to the vet, but her request was rejected, prompting the unusual legal action.
They cited an allowance for absences that can be categorized as "serious or family personal reasons", The Guardian writes.
Their argument was underpinned by a provision in Italy's penal code that provides for people who abandon an animal to "grave suffering" to be jailed for a year and fined up to €10,000.
Italian animal advocacy group LAV says it helped persuade public La Sapienza University to let her use two days' family sick leave.
Cucciola is said to be recovering well with her owner by her side.
Animal activists told The Telegraph that the ruling showed that Italy believes that pets are "members of the family" and that the case will set an important precedent.
Kate Palmer, head of advisory at Peninsula, an employment law consultancy, said that in the United Kingdom, pets are not included within the statutory definition that entitles employees to pair or unpaid lave.