var list = new List<KeyValuePair<string, int>>();
list.Add(new KeyValuePair<string, int>("Cat", 1));
list.Add(new KeyValuePair<string, int>("Dog", 2));
list.Add(new KeyValuePair<string, int>("Rabbit", 4));
int removalStatus = list.RemoveAll(x => x.Key == "Rabbit");
if (removalStatus == 1)
{
list.Add(new KeyValuePair<string, int>("Rabbit", 5));
}