NAPA, Calif. — Evacuees from the fires raging in the Sonoma and Napa valleys arrived at shelters leading dogs, carrying cats in crates and often with birds, chinchillas and other exotic pets in cages.

Most shelters feature rooms set aside for pets, with dogs and cats carefully separated. But it’s not just hamsters. Horses, llamas, chickens, goats and pigs are also streaming out of fire areas with their owners.

Horses are most difficult to house. The fires crossed into Solano County northeast of San Francisco on Tuesday and dozens of horses are now being housed at the…