append pandas dataframe automatically cast as float but want int

It's because your initial dataframe is empty. Initialize it with some integer column.

df = pd.DataFrame(dict(A=[], test=[], another=[]), dtype=int)
df.append(dict(A=3, test=4, another=5), ignore_index=True)

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Had I done

df = pd.DataFrame()
df.append(dict(A=3, test=4, another=5), ignore_index=True)