Perrito vs. cachorro
In Spanish, both perrito and cachorro can translate to puppy, but they are not always interchangeable. The choice between them depends on the emphasis you want to place: perrito focuses on affection and small size, while cachorro is a more general, biological term for any young animal, including a dog.
Perrito
A2This word is the diminutive of perro (dog). The -ito suffix adds a sense of smallness, cuteness, and endearment. While it's very commonly used for puppies, it can also refer to any small adult dog that evokes affection. It is used exclusively for dogs.
Mi perrito tiene solo tres meses y es muy juguetón.
(My little puppy is only three months old and is very playful.)
¡Mira qué perrito tan adorable encontré en la calle!
(Look at what an adorable little dog I found on the street!)
Aunque mi chihuahua ya es adulto, para mí siempre será mi perrito.
(Even though my chihuahua is an adult, for me he will always be my little dog.)
El perrito aprendió a dar la pata muy rápido.
(The puppy learned to shake hands very quickly.)
Adoptamos un perrito del refugio el fin de semana pasado.
(We adopted a puppy from the shelter last weekend.)
Cachorro
B1This is the standard, more formal term for a young dog that has not reached adulthood. More broadly, cachorro is the correct biological term for the young of many mammals, such as lions, bears, wolves, and cats. Its primary focus is on the animal's age, not its size or cuteness.
La camada entera de cachorros está sana, dijo el veterinario.
(The entire litter of puppies is healthy, said the veterinarian.)
Un cachorro de golden retriever requiere mucho ejercicio.
(A golden retriever puppy requires a lot of exercise.)
Los cachorros necesitan una dieta especial para crecer fuertes.
(Puppies need a special diet to grow strong.)
En el safari vimos un cachorro de león con su madre.
(On the safari, we saw a lion cub with its mother.)
Es importante socializar a un cachorro desde una edad temprana.
(It is important to socialize a puppy from a young age.)
Summary
In short, use perrito when you want to be affectionate and emphasize the smallness or cuteness of a dog, whether it's a puppy or a small breed. Use cachorro when you are referring specifically to the young age of a dog in a more general or formal context. Remember that only cachorro can be used for other baby mammals like cubs or whelps.