[{key1: [val1, val2]}, {key2: [val3, val4]}, {key3: [val5, val6]}, ...]

my_list = [3423, 77813, 12, 153, 1899]

[{3423:['dog', 'cat']}, {77813:['dog', 'cat']}, {12:['dog', 'cat']},
    {153:['dog', 'cat']}, {1899:['dog', 'cat']}]

for i in my_list:
    d = {}   ## create a dictionary 'd'
    d[i] = [].append('dog')  ## or  `d[i] = ['dog'].append('cat')`
    my_list.append(d)   ## here is a bug
    my_list.remove(i) ## remove the item from the list

new_list = []
for i in my_list:
    d = {}
    d[i] = [].append('dog')
    new_list.append(d)
    my_list.remove(i)