An excellent article from the journal "Past & Present" (vol.246, #1, Feb. 2020,pp.69-108) entitled Slave Hounds and Abolition in the Americas, by Tyler D. Parry, and Charlton W. Yingling, is available to read online or as a downloadable pdf. It covers the breeding and spread of slave-catching dogs, most notably the now-extinct Cuban bloodhound, in Latin America and the Caribbean, and their subsequent introduction and use in the southern United States. This breed was most feared and effective because they were not merely trackers, but fighting dogs, related to mastiffs and bulldogs rather than modern bloodhounds, and were bred to attack and maim their prey.
"The most extensively documented deployment of slave hounds, which also provoked the most vitriolic national divisions, occurred in the antebellum American South and built upon Caribbean foundations. As early as 1790, newspapers in the North were protesting the occasional use of slave dogs. However, later spectacular stories circulating from Jamaica and Haiti also prompted curiosity among American slaveholders about this form of white power. By the 1820s slaves and dogs were fighting in the South, for example, when a runaway in Georgia was severely wounded by hounds after killing one of his assailants with a dagger. The bishop of Charleston was accosted by 'dogs that were set to guard against the negroes', following a trip to Haiti in the 1830s. The use of dogs increased during that decade, especially with the Second Seminole War in Florida (1835–42). The first recorded sale of Cuban dogs into the United States came with this conflict, when the US military apparently purchased three such dogs for $151.72 each, though in consequence Northerners lamented that 'the American flag was disgraced with the importation of blood-hounds'."