On 16 April, 04, I gave a link to the website Sephardic Folk Literature, which includes many versions of "Don Gato" collected in Spain, Latin America, New Mexico and Morocco. One, collected in Morocco, Tetuán, by Susana Weich-Shahak, is a child's version, used to teach Jewish children. It is brief.

Estaba el señor don Gato
sentadito en su tejado
con la(s) mano en la cintura
y la otra en el costado.
Por ahí pasóo una gata
con las ojos 'relumbrando;
la gata (sic), por darle un beso,
se cayó de su tejado,
Mandaron por los ductores,
Ductores y cirujanos;
uno le mira la pierna,
otro le mira el costado.
Señor Gato está muy malo,
señor Gato ya se ha muerto;
ya lo llevan a enterrar
y la plaza del pescado,
al olor de las sardinas
el gato ha resucitado.

Basic sheet music is given, and the song may be downloaded.
Music at Don Gato music
Discussion and text at Don Gato text
If these don't work, use the index link I gave 16 April 04 and scroll way down.

Age unknown. Apparently there are no known written records of the song before the 18th c, so it cannot be shown that it was sung in Spain before the expulsion of the Jews. Sephardic songs continued to evolve through time, with new additions, so the fact that a song is in their current literature is not proof of 15th c. existence.