adding items to an array

I have a listbox that breaks down a comma delimited list from a single column and lists the individual items for a user to select, which is then fed back to an autofilter to hide the rows that don't contain the items anywhere in the cell. ie

a2 = cat, dog, mouse
a3 = cat, mouse
a4 = dog, mouse
a5 =dog
a6 =dog

if user selects "dog" the array cycles through the cells that contain dog and should add them to the array. so a2, a4, a5 should be added. a6 should be ignored because it would already be in the array. my code seems to be adding a6 as well so it seems to slow the code down because it's adding to many duplicates. i'm sure it's a simple syntax error on my part but i cant seem to find it. any help would be awesome.

      Set rng = Range(CatCol & "1:" & CatCol & LastRow)
       
        For j = 1 To LastRow
        
        
        cellv = UCase(Range(CatCol & j))
            
            For i = LBound(MyArray) To UBound(MyArray)
                If Not IsEmpty(MyArray(i)) Then
                    If InStr(UCase(Range(CatCol & j)), UCase(MyArray(i))) Then
                        If UCase(Range(CatCol & j)) <> UCase(MyArray(i)) Then
                            MyArray(UBound(MyArray)) = Range(CatCol & j)
                            ReDim Preserve MyArray(UBound(MyArray) + 1)
                        End If
                    End If
                End If
                
            Next i
        Next j