Gender Comparison

By Small Furries - June 20, 2019

Buck – Male Rat
Doe – Female Rat

When thinking about rats, the first things to think about is where they are coming from and what coat pattern or colour you’d like ( if purchasing from a breeder ) but you’re also going to think about whether you want males or females!

Because of the complications of surgery, many people do not get their rats neutered and keep them in separate groups, males and females, to prevent pregnancy. 

When you first purchase two rats it is always best to get two of the same gender, and where you can, from the same litter so they are even more bonded and less likely to ever fight.


Male rats tend to grow much larger compared to females, although if you only have males or only have females, you will not really notice it. Some males can also be small and you may end up with one large rat and one small rat, it all depends on their genetics but if you purchase from the same litter they should be reasonably the same size.

Adult male rats average between 300-500g and females should weigh between 250 – 300g. However, some females can be very small and although they are healthy and not underweight, they may stay around the lower end of the scale! 

This estimate is likely based on lab rats, but with the domestication of fancy rats, our rats tend to grow slightly larger and some males can be up to 800g and still not overweight!

Taken from one of my favourite websites here is a chart showing the individual weights of three male rats over the course of two years;


Apart from the obvious difference, and I mean the huge testicles that male rats support, there are a few other differences. Male rats do not have nipples, at all, although there has been a few very rare cases. 

This helps you when identifying new babies or even new rats in general as you will surely know whether they are male or female by looking for nipples!
Female rats have 12 nipples from birth but they can be harder to find when your rats starts growing thick fur. 

If you have to purchase from a pet store, check the rats over yourself, look for nipples and testicles in males so that you do not end up with an accidental litter! Male rats show testicles from a very young age, although they can retract them when very cold, you should still not be able to find any nipples!


Temperament in rats completely vary depending on the rat’s genetics, early life and how well they were cared for by their own mother and their breeders! All of these factors make up your rats personality and it is hard to say that one gender is cuddlier or less cuddly because both genders can be both!

In my experience, male rats are much more docile than females. They prefer human contact and they will quite happily sit still on your lap, fall asleep or just take a massage from you! They tend to grow bigger and because they are less active than females, they are more likely to gain weight easier and look cuddlier!

Female rats are much more hyperactive and playful, I find they pick up on tricks easier and can be potty trained much easier too as they are hanging on your every word! Female rats usually are not cuddly until they are much older and their hormones calm down, but that does not mean they do not make great pets! 

They are more inquisitive and curious, they want to be involved in everything you are doing and get themselves in more trouble, which can be hilarious! They normally have a slightly higher metabolism due to how active they are, but obesity can still be an issue if you are not careful!


The common consensus is that males are more aggressive than females due to their hormones but I strongly disagree, female rats are very maternal and can become very protective of their other cage mates, or ill rats. Both genders can be territorial over their space, which can turn into aggression if you are not wanted or trusted near their cage.

I have personally found that females can be nippier with humans due to their hyperactive nature, although this is usually playful, rats can nip you as a warning and if you continue to irritate them, they may bite you. 

Both females and males will calm down at about 18 months old, however, males can calm down earlier and females can be hyperactive for the majority of their life.  Because of this, it may seem like female rats play fight or wrestle more often, whereas males will stop fighting as they age.

When you hear about an owner being bitten, the rat is usually female as many people will neuter their males at any sign of aggression but spaying females can be an invasive surgery. However, many people will argue that spaying females can have huge health benefits and can prevent the most common mammary tumours.


As mentioned above, females can and usually will suffer from severe mammary tumours. Male rats can get testicular cancer, like most animals, and neutering both genders can lessen the chance of your rats developing these tumours. Check out my Rat Tumour Article Here.

Common health issues over both genders

  • Respiratory infections
  • Urinary tract infections
  • Ear infections
  • Skin problems
  • Tumours
  • Abscesses
  • Strokes/Seizures
  • Obesity
  • Mycoplasmosis
  • Heat stress
  • Bumble foot

Both genders are as good as each other, they are very different but this gives you the flexibility to choose which kind of pet rat you’d like! Just remember that even if you purchase two females, they may be docile, and two males may be hyperactive!

 The joy is watching your baby rats grow up and learning their individual personalities as every single rat is completely different, this is what makes them so special!


Small Furries 2019 Extended Diploma in Animal Management



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