How to Transition Your Rat's Diet

Transition from your breeder's diet to your pet rat's long-term diet.

Introduction

When you bring home a new rat from a breeder, there’s already a lot to adjust to: a new space, new people, new routines—and sometimes, a new food. Transitioning your rat from the breeder’s current diet to your preferred pet diet should be done gradually and thoughtfully, not just for comfort, but for their digestive health.

At Coastline Pets, we make this process easy by sending you home with a week’s worth of the food your rat is currently eating—just enough to support a smooth, stress-free transition.

Why Gradual Transitioning Matters

Rats have sensitive digestive systems, and sudden changes to their diet can cause:

  • Loose or soft stools

  • Mild bloating or discomfort

  • Hesitation to eat the unfamiliar food


To minimize this, all dietary changes should be gradual, allowing your rat’s gut flora time to adjust to the new ingredients and nutrient profile.

How to Transition Over 1 Week

Here's a simple 7-day feeding guide using the food provided by Coastline Pets alongside your chosen pet diet:

  • Day 1-2: 75% Old Food, 25% New Food

  • Day 3-4: 50% Old Food, 50% New Food

  • Day 5-6: 25% Old Food, 75% New Food

  • Day 7+: 0% Old Food, 100% New Food


Mix the foods thoroughly in the same dish so your rat can nibble and compare at their own pace.

What Diets Do We Recommend?

Our rats are weaned and raised on Mazuri Rodent Diet, a nutritionally complete lab block trusted by breeders and pet owners alike. We highly recommend continuing with Mazuri if you’re unsure what to choose—it provides consistency and is widely available in both pet stores and online.

Other acceptable lab block brands (though we encourage you to research carefully) include:

  • OXBOW Essentials Adult Rat Food (especially for older rats)

  • Science Selective Rat Food (UK-based, sometimes available in the U.S.)


Avoid diets that rely heavily on:

  • Loose seed or grain mixes

  • Sugary or brightly colored ingredients

  • Foods marketed as “gourmet” or “treat-heavy”


While variety can be enriching, it should never come at the cost of balanced nutrition.

Is Stool Change Normal?

Yes—minor changes in stool consistency during the transition period are completely normal.

You might notice:

  • Slightly softer or looser droppings

  • Increased output for a few days

  • More frequent elimination


This is the gut adjusting to new fiber sources and protein levels. However, contact your vet if you notice:

  • Very watery diarrhea for more than 24 hours

  • Lethargy, dehydration, or sudden weight loss

  • Refusal to eat or drink for more than 12 hours


These could be signs of intolerance, illness, or stress-related digestive upset that needs professional support.

What If My Rat Won't Eat the New Food?

Rats are curious but cautious creatures—especially when young or newly rehomed.

If your rat is uninterested in the new food:

  • Stick to the gradual mix and don’t introduce new snacks or treats yet

  • Try offering it at different times of day


You can also make the transition easier by continuing with Mazuri, the same high-quality food they were raised on. Many adopters choose to keep Mazuri as their long-term diet for consistency and peace of mind.