How to Care for Young Small Mammals

Written by Oxbow

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November 12, 2021🞄

by Dianne Cook, LVT

Regardless of species, there are few things quite as adorable as young animals. With big eyes, button noses, and boundless curiosity, young animals have a way of quickly burrowing their way into their pet parents’ hearts. While welcoming a young small mammal (or 2 or 3) into your home is sure to fill your days with adorable antics, those quickly maturing bodies require some specialized care. Luckily, with the proper diet, environment, species-appropriate veterinary care, and lots and lots of love, you can help your little one grow up healthy and strong.

What Constitutes As “Young”?

Just like humans, every individual animal matures at their own rate. While some may fill out at a relatively young age, others take longer to reach their full adult size. These differences can be especially apparent between two breeds of the same species (e.g. Flemish giant vs Holland lop) but may also be noted between littermates.

The following list provides the average ages during which small mammals are considered “young.” It’s always best to work with an experienced exotics veterinarian to ensure your little one’s care is tailored to their unique growth rate and individualized needs.

  • Rabbits: birth – 12 months
    • Some giant breeds are considered adults at 9 months
  • Guinea Pigs: birth – 6 months
  • Chinchillas: birth – 12 months
    • Many grow and mature until they’re closer to 2 years of age
  • Rats: birth – 6 months
  • Hamsters: birth – 3 months
    • On average – there are some differences between breeds
  • Gerbils: birth – 3 or 4 months
  • Mice: birth – 3 months

A Baby by any Other Name

When most people see a baby rabbit, they immediately think “bunny.” Guinea pig babies are often called “piglets,” and baby hamsters are sometimes referred to as “hamlets.” While these colloquial terms are not necessarily incorrect, it may come as a surprise to learn that baby small mammals technically fall into one of two teams: team pups or team kits.

Team Pups Team Kits 
Guinea PigsRabbits

A Word on Neonates

Whether resulting from a planned or unplanned pregnancy, the discovery of a nest full of teeny-tiny babies can result in shock, awe, and a bit of trepidation. Though you’ll want to keep a watchful eye on the babies to make sure they are growing and developing as expected, under most circumstances, it is best to leave mom and her offspring alone as much as possible.

Species like guinea pigs and chinchillas are born with their eyes open and look like miniature, fully furred versions of their parents. These little ones are generally safe to be handled about a week after they are born. Rabbits, rats, hamsters, gerbils, and mice give birth to less-developed babies that are born with closed eyes and no fur. As a result, it’s best to avoid handling these species until they have a full hair coat, are old enough to leave the nest, and are eating some solid foods well on their own.

It is also important to note that many small mammal mothers can appear as though they are not taking good care of their babies even though they are. This is especially true for small herbivores. For instance, rabbits tend to nurse their babies 2 – 3 times a day (typically during dawn and dusk) and will otherwise leave the nest box unattended. If the babies are active and appear to have full bellies, mom is doing her job.

Unfortunately, as with any animal, there are times that a mother may pass away during (or just after) delivery, or she may abandon or reject her babies altogether. If you are certain mom is no longer capable of or willing to care for her babies, it is essential to contact an exotics veterinarian immediately to discuss proper care and supplementation of the litter.

Protein, Calcium, and Calories, Oh My!

During their first few weeks-to-months of life, small mammals grow astonishingly fast. While their little bodies go through this time of rapid maturation, higher levels of certain nutrients are required to ensure the proper formation of organs, nerves, bones, muscles, and connective tissues. As newborns, their mothers’ milk (or a milk replacement formula) provides all the necessary nutritional requirements.

Once weaned, however, pet parents need to provide their young friends with a diet rich in protein (especially amino acids), calcium, and extra energy (i.e. calories) to aid in the growth of a strong, healthy body. To learn more about the importance of feeding a species-specific diet formulated specifically for young pets, please read the following article: The Importance of Young Formulas for Small Animals. 

Caring for Young Herbivores


During their formative years, young herbivores (rabbits, guinea pigs, and chinchillas) should be fed a high-quality, fortified, alfalfa-based pelleted diet. Throughout this stage of life, it is important your little one is fed an unlimited quantity of pellets to ensure they are getting plenty of protein and calcium as well as their daily allotment of micronutrients.

In addition to pellets, youngsters should also have constant access to an unlimited supply of grass-hay varieties mixed with loose alfalfa. Alfalfa is rich in protein and calcium, making it a staple of a healthy young herbivore diet, but adding a selection of grass hays provides nutritional enrichment, stimulates your young friend’s natural foraging behavior, and helps broaden their palate by exposing them to the different aromas, tastes, and textures of hay.

Finally, a daily serving of fresh, species-appropriate greens and veggies make up a well-rounded herbivore diet. Not only do fresh greens provide additional vitamins and minerals to your little one’s diet, but they also serve as an easy (and delicious) way to increase hydration and support your kiddo’s instinctual foraging behavior. Make sure to introduce new greens gradually, one variety at a time, to allow your little one’s maturing digestive system time to adjust. It is always best to work with a trusted veterinarian to ensure the variety of greens (and their overall diet) is modified to meet the needs of your little one’s species, growth-rate, and personal tolerances/preference.


As naturally active, curious animals, young small herbivores require a large, secure area in which to play, explore, and re-energize. While some little ones can be trusted to roam freely throughout a pet-proofed space, others do best spending a portion of their day in the protected comfort of a species-appropriate enclosure. Regardless of their habitat, it is essential for herbivores of all ages to have access to a safe, supervised area of the home in which they can burn off excess energy and stimulate their mind. Not only will this time provide an excellent opportunity for you to start building a strong human-animal bond, it will also help your fur baby develop strong bones, healthy muscle mass, and a sharp mind. Keeping a variety of enrichment items in this space will help keep interest piqued and prevent curious little mouths from chewing on things they shouldn’t.

Caring for Young Omnivores


Small omnivores (rats, hamsters, gerbils, and mice) are physiologically designed to consume a wide variety of foods. Though protein, calcium, and additional calories (energy) are equally important for young omnivores as they are for young herbivores, the way these nutrients are consumed should be uniquely tailored to your little one’s species. The most substantial portion of a healthy omnivorous diet should include a species-specific, fortified, uniform pellet/rodent block. A uniform pellet or block will help lay a solid foundation for a well-balanced diet while helping to avoid obesity and other common health-related concerns seen these species.

Though a high-quality pellet or block serves as the backbone of a healthy young omnivore diet, offering a variety of supplemental foods (like fresh produce, grains, and proteins) will round out your young friend’s menu, provide additional macro- and micronutrients, and serve as a healthy outlet for your kiddo’s intrinsic desire to forage. Small omnivores are naturally opportunistic and tend to be more than willing to sample a wide variety of supplemental foods, but options should be introduced gradually and in appropriately sized portions to avoid any digestive woes or selective feeding concerns. As always, working with an exotics-savvy veterinarian is advisable.


Though small in stature, young omnivores have big personalities and seemingly boundless energy. As a result, it is essential to provide them with the largest, species-appropriate enclosure possible. An appropriate small omnivore habitat will feature multiple levels for climbing and exploring, an appropriate outlet for expending pent-up energy (e.g. species-appropriate exercise wheel, all-natural chews, tunnels, climbing ropes, etc), and plenty of soft bedding in which to nest and stash their food. Even though a spacious enclosure will give your young friend room to explore, they should always have daily, closely supervised time outside of their habitat to run around and interact with their favorite humans.

Learn More

Rabbit Life Cycle Stages: Feeding and Care Tips
Guinea Pig Life Cycle Stages: Feeding and Care Tips

What Should I Feed to My Pet Rat?
Selective Feeding in Rats, Mice, Hamsters, and Gerbils