Le terme (English term or phrase) ne devrait pas être ''eligible'' mais plutôt ''also-eligible'':

American horse racing dictionary

A horse officially entered for a race, but not permitted to start unless the field is reduced by scratches below a specified number.

http://dictionary.babylon.com/also-eligible/


Les dispositions réglementaires préciseront en outre comment la « règle de substitution du favori » pouvant être appliquée sur les chevaux « aussi éligibles » et sur ceux de remplacement choisis par le client.

http://www4.agr.gc.ca/AAFC-AAC/display-afficher.do?id=120483...

Regulations will outline the requirements for the possible application of the "favourite substitution rule", betting on "also eligibles", and patron-selected alternate runners.

http://www4.agr.gc.ca/AAFC-AAC/display-afficher.do?id=120483...



Autres exemples:

Kentucky Derby: An also-eligible list would have allowed Sway Away to draw in

http://www.drf.com/news/kentucky-derby-also-eligible-list-wo...

Also-eligible - a horse that is entered but that does not make the body of the race at entry time may be placed on the also-eligible list. For example, a race may have 12 entries and four also-eligibles or "alsos.” A horse on the alsos cannot get into the actual race unless a horse is scratched out of the body of the race. If no horses scratch (are withdrawn) from the body of a race before a prescribed time, the also-eligible horses are also scratched.

http://www.predictem.com/horse/terms-a.php

Top 9 money-winners declared will advance to the final, plus 2 also-eligibles

http://www.raceromp.com/slots-cup-series/


This race will be drawn with 14 starters and 6 also eligibles.

http://www.centralentryoffice.com/ConditionBook/Spring/Middl...