"For my days are consumed like smoke, and my bones are burned as an hearth."—Psalm cii.
Animal heat is derived from the slow combustion of carbon in the blood of animals with the oxygen of the air which the animals breathe.
Latent heat (or more properly latent caloric) is that which exists, in some degree, in all bodies, though it may be imperceptible to the senses.
89. Is there latent caloric in ice, snow, water, marble, &c?
Yes; there is some amount of caloric in all substances.