Despite taking in tens of thousands of euro less than previous years, the charity received a "major boost" by selling off properties and parts of estates handed over by supporters.
According to documents filed with the Companies Office, some €801,582 was received from donations and the sale proceeds last year.
Speaking to the Herald, the charity's chief executive Noel Griffin said he was "overwhelmed" by the generosity still being shown in the recession.
"While our annual accounts appear to show that our proceeds from the public has increased, this is due to the sale of a couple of properties in 2011. Overall our donations are down about 30pc," he said.
"But I have to emphasise how overwhelmed we are by the level of support the charity is getting. Although people are giving less, they are still showing a tremendous support for animals.
"In one instance recently, we had two guys come into the office and say, 'we can't afford to give any money but we will help out on the land'. It's that type of thing that comes with the recession."
Mr Griffin spoke of the "wonderful shock" the charity receives when it is left houses and estates by people in their wills.
"People are very good to us. Often we just get a phone call to say that we have been included in a will. It can just come straight out of the blue. They don't say it to us in advance. It's a wonderful shock when it does happen. Some people are just so loving towards animals and our cause."
In one case this year, a woman from Co Clare left a house to the ISPCC based on just one condition -- that the charity provides a home to her two dogs.
"You'd wonder if the woman is looking down really happy that her two dogs are together in a happy home," Mr Griffin told the Herald.