The plural of hoof is hoofs or hooves.
The tough underside of the foot of some mammals such as horses and sheep.
Most English nouns form their plural by adding -s or -es to the end of the word. Most English nouns ending in the letter -f however, have an irregular plural form and replace the f with -ves.
The plural for the word hoof actually allows both plural forms. The plural of hoof can be hoofs or hooves.
Both forms of the word are acceptable but these days the spelling hooves is more commonly used in written English as you can see from the graph below of instances of both words in written English since 1900.
This is in contrast to the word roof, whose only accepted plural is roofs and not 'rooves'.
Nobody said that the English language was a logical one!
Singular Example: For such a large animal a horse's hoof is not so large, measuring 76–100 mm (2½ to 4 inches) long.
Plural Example: Bison are the largest animals with hooves. The males of the species can grow to be up to 6 feet tall and weigh up to 2,000 pounds!
The graph shows the occurances of the plural of hoof in written English since 1800 using Google's Ngram Viewer.
Hooved animals include deer, sheep and even hippopotamuses but tapirs are animals native to South America which have multiple hooves on each foot!