''Thoroughbred'' is a LongRunner series by Joanna Campbell. It follows several generations of equestrians and the horses they raise.

The series starts with Ashleigh, a girl who had to say goodbye to her beloved Stardust when her family sold off their horse farm to pay medical debts. They get a job at Townsend Acres, where Ashleigh rears a runt horse named Wonder, who nearly dies as a foal several times. Ashleigh worries about Wonder's future and wants to give her a chance. That's not as easy when a lot of people in the horse world, including the Townsend son, want to ruin her filly.

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!! Tropes for this series include:

* EtTuBrute: Ashleigh is devastated and furious when Caroline reveals she's been dating Brad. She calls her sister a traitor and says that Caro probably ''wants'' her and Wonder to fail.
* FantasyForbiddingFather: When Ashleigh spends too much time on Wonder and not enough on schoolwork, her parents tell her she can't let a horse take priority over her grades. They make her study until she pulls them back up before she can go back to caring for Wonder.
* KickTheDog:
** You could make a drinking game out of every time Brad insults Ashleigh or Wonder. [[spoiler:In book three, he injures Wonder while riding her, much to Ashleigh's consternation]].
** There's also how Wonder's first trainer whips her for every little aggravation and makes her scared to have anyone riding her.
* OpenMouthInsertFoot: Caroline has this problem as an older sister. She thinks the world of Brad, even though he bullies Ashleigh, and parrots his opinions about not succeeding in training Wonder.
* PonyTale: Obviously. The formula that the first few books follow are about Ashleigh bonding with a runt named Wonder, and rearing her so she won't be sold to another farm.
* ReplacementGoldfish: Subverted. Ashleigh doesn't replace Stardust with Wonder, cherishing both of the horses.
* WhatDoesSheSeeInHim: Ashleigh doesn't know why Caroline likes Brad Townsend, a snobby {{Jerkass}} who mocks Wonder for being a runt.

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