He was responding to a question from the Southern District Health Board's hospitals advisory committee chairman, Paul Menzies, this month about whether the board was "capturing the hearts and minds of participants" in planning for shared services.
Mr Tulloch said there had been a "small measure of improvement".
He told a recent board meeting there were significant differences in how the two main hospitals ran their services and it was sometimes difficult to tell "who needs to speak to whom and at which level".
There was a slow realisation what was needed was the provision of an equitable service for the entire southern population, rather than the hospitals being independent providers on different sites.
Rheumatology services, endocrinology, urology and ophthalmology have begun work on developing shared services.
Chief executive Brian Rousseau said several other services - the health of older people, respiratory, mental health, orthopaedics, general surgery and audiology - had either begun discussions or had indicated they wished to do so.
Asked after the meeting if work had stopped on developing gastroenterology across the southern region, Otago chief operating officer Vivian Blake said "we are not pressing for it to be a southern service just yet" because of a number of issues in Otago which needed to be addressed.
These included staffing, the ability to carry out the number of colonoscopies required and the need to upgrade the facilities.
