how to configure postgresql to display messages in italian

Hello,

I would like to ask you how to configure Pg to display messages in
italian instead of english.
I'm using PostgreSQL versione 8.1.8

For example, my pg display data as:

\d cani
Table "public.cani"
Column | Type
| Modifiers
--------------------------+-----------------------------+------------------------------------------------------
matricola | character varying(17) | not null
iscrizione | date | not null
nome_cane | character varying(12) |

I would like to have it as:
Tabella "public.cani"
Colonna | Tipo
| Modificatori
------------------------+-----------------------------+----------------------------------------------------
matricola | character varying(17) | not null
iscrizione | date | not null
nome_cane | character varying(12) |

thank you,
jo