What's the difference between thoroughbred and underbred?

Thoroughbred

Definition:

(a.) Bred from the best blood through a long line; pure-blooded; -- said of stock, as horses. Hence, having the characteristics of such breeding; mettlesome; courageous; of elegant form, or the like.
(n.) A thoroughbred animal, especially a horse.

Example Sentences:

(1) A 5-year-old Thoroughbred gelding was examined because of a small axillary wound sustained 5 days earlier and had resulted in extensive subcutaneous emphysema.
(2) Three basic techniques (and one modified technique) were developed, allowing successful excision of subepiglottic cysts in 10 horses (5 Standardbreds, 4 Thoroughbreds, and 1 Quarter Horse; mean age, 3.5 years) via peroral approach.
(3) It's so magnificent, like the swishing mane of a thoroughbred stallion … Too late, snip snip, off it comes.
(4) Plasma concentrations of estrogens, gestagens, cortisol (F), 13, 14-dihydro, 15-keto PGF2 alpha (PGFM) and pregnant mare serum gonadotropin (PMSG) in 10 Thoroughbred mares were measured for a 11-month pregnancy period.
(5) Thoroughbred horses were run at maximal O2 uptake on a high-speed treadmill until fatigued.
(6) Esophageal stenosis was diagnosed in a 7-day-old Thoroughbred foal referred for evaluation of bilateral milky nasal discharge.
(7) Thoroughbred horses have been bred exclusively for racing in England since Tudor times and thoroughbred horse racing is now practised in over 40 countries and involves more than half-a-million horses worldwide.
(8) No significant associations were detected between laryngeal hemiplegia and any ELA antigen in Thoroughbreds.
(9) The source of a previously described radiolucent crescent in the flexor cortex of the distal sesamoid (navicular) bone on the palmaro45 degrees proximal-palmarodistal oblique (Pa45 degrees Pr-PaDio) clinical radiographic projection was investigated in 48 forelimb navicular bones from 24 Thoroughbreds by use of high-detail radiography and x-ray computed tomography (CT).
(10) The difficulties that arise in filling out marking certificates for thoroughbreds are described.
(11) Her horse Barber’s Shop won the Tattersalls & RoR Thoroughbred Ridden Show.
(12) A Thoroughbred stallion with erectile dysfunction following paraphimosis was managed to allow consistent ejaculation.
(13) A project to determine if intraarticular corticosteroid therapy was deleterious to the racing Thoroughbred was carried out in the 1971, 1972, and 1973 racing seasons.
(14) Changes in concentration of a number of blood metabolites in 30 thoroughbred horses were recorded after an 1110 metre race.
(15) Gross post mortem examinations were performed on the lungs of 26 Thoroughbred horses of known exercise-induced pulmonary haemorrhage (EIPH) status.
(16) The gluteus medius of two killed Thoroughbred horses were sampled along the muscle and across the muscle at four different depths.
(17) The cumulative pregnancy rate after five services was 85% for Quarter-horse and 77% for Thoroughbred mares (P less than 0-05).
(18) Following either exercise or intravenous injection of adrenaline in six thoroughbreds, there was an increase in erythrocyte creatine content and a decrease in ATP concentration.
(19) Two foals aged 35 and 48 h from 2 Thoroughbred studs died several hours after developing clinical signs of depression, severe haemorrhagic diarrhoea and dehydration.
(20) Six Thoroughbred horses were biopsied the day before and within 30 minutes of completion of the speed and endurance test.