So please be mature here. I am well aware that these photos may be disturbing to some viewers. 
With that aside.
These were taken to assist people in autopsying their own mice. Some people may be interested in doing this, but not know how, or think that it would be too gross to try. Well, you can at least look here, and learn some things about it, before you try.
This is a very simple thing that you can do at home. Taking a mouse to the vet for a necropsy can cost hundreds, or thousands of dollars. Some things, you should check with your vet about, but for most things like cancer, ulcers, cysts, internal bleeding, megacolon, etc, there are obvious signs of the problem inside the mouse.
THIS MOUSE WAS NOT KILLED JUST FOR THIS TUTORIAL.
It was culled, because it was growing obese (from a brindle line) and I found it necessary. Fortunately, he is now giving back to the mousing community, by helping with this guide.
Now, without further ado, here are the tools you will need to begin this proceedure:
You will need an exacto knife. I find that the ones with the sharp, triangle point are the best, because you can use the tiny tip, which helps on such a small animal.
![]()
You will need pins. I like T-pins because it makes them easy to press down, and they are cheap. Thumb tacks work, as well as most any type of sewing pins.
![]()
You will of course need, your mouse in question. If it was in the freezer, let it thaw for a few hours, until there are no more cold spots. But not too long, or the insides will start to spoil.
![]()
You will also need a small piece of cardboard, to pin your mouse down to later. I didn't take a picture of this, you all know what cardboard looks like, don't you!?
YOU SHOULD ALSO WEAR GLOVES DURING THIS PROCEDURE. FOR YOUR OWN SAFETY!
STEP 1
Place your mouse on it's back, on the cardboard piece you have chosen. Carefully pinch the skin up on the mouse's chest (at the red dot) and with your other hand, work the tip of your blade CAREFULLY beneath the skin, and begin CAREFULLY cutting downwards, with your blade facing UP. You do not want to puncture the abdominal cavity at this point. If the mouse is a male (like this one), you can cut slightly off center to avoid his penis and testicles, and cut nearly all the way to his anus. Once you've gone that far down, carefully slice the skin from the initial incision, up to the throat.
![]()
STEP 2
Your mouse should now look like this (minus the red arrows ):
![]()
Carefully grasp the skin by the points indicated by red dots, and peel it away from the mouse's carcass. It should peel back very easily. You CAN use your blade for this, but you may end up cutting through the skin, if you are not skilled in this.
STEP 3
Your mouse should now look like this:
![]()
Carefully pull the skin away from the body, and tack it to the cardboard at four points, making it into a neat square, or rectangle.
STEP4
Your mouse should now look like this:
![]()
If anything about this would be hard, this would be it. The blade you are using MUST be extremely sharp, or you will end up puncturing something you don't want to. If you are using an exacto knife with an old blade, now would be the time to get a new one. CAREFULLY cut the membrane on the breast bone, and continue downwards (pinching the membrane between your fingers, helps keep it tight and away from the internal organs) until you reach the mouse's anus. Then, carefully cut the membrane down the sides (where the lines indicate) and peel it away from the guts.
STEP 5
Your mouse should now look like this:
![]()
Here you can see most of the organs. Things like the heart and lungs are up inside the chest cavity, so if you need to check them, just carefully pull out the other organs. One by one is usually best, so as not to get everything messy. The kidneys are under a few things, but are very recognizable. This is a male mouse, so you can see his testicles near the bottom.
I'm not going to go into more detail, and take out each organ at the moment. This is just to help people get started. If you were looking for a cancer, it should be easy to find.
This mouse suffered from obesity. After I did the autopsy, I fully skinned him, and took the fat off of the carcass, for reference. This mouse was pretty large, and it only took the small amount of fat you see here, to cause his problems:
![]()
It helps put things into perspective. You'd figure there would be more fat, but no.
If you do an autopsy, and find something that you think is abnormal, but cannot identify, feel free to post a photo here, and we will try to help you find out what was wrong. If we cannot help you, the best thing to do would be to freeze the specimen that you found, and give it to your vet for a better diagnosis.
I hope this can be beneficial to people, and educational. I know, it's not pretty, but it's life, it's science, and it can help you to better understand problems when they arise in your other, living mice.
Thanks. I hope this helps you.
With that aside.
These were taken to assist people in autopsying their own mice. Some people may be interested in doing this, but not know how, or think that it would be too gross to try. Well, you can at least look here, and learn some things about it, before you try.
This is a very simple thing that you can do at home. Taking a mouse to the vet for a necropsy can cost hundreds, or thousands of dollars. Some things, you should check with your vet about, but for most things like cancer, ulcers, cysts, internal bleeding, megacolon, etc, there are obvious signs of the problem inside the mouse.
THIS MOUSE WAS NOT KILLED JUST FOR THIS TUTORIAL.
It was culled, because it was growing obese (from a brindle line) and I found it necessary. Fortunately, he is now giving back to the mousing community, by helping with this guide.
Now, without further ado, here are the tools you will need to begin this proceedure:
You will need an exacto knife. I find that the ones with the sharp, triangle point are the best, because you can use the tiny tip, which helps on such a small animal.
You will need pins. I like T-pins because it makes them easy to press down, and they are cheap. Thumb tacks work, as well as most any type of sewing pins.
You will of course need, your mouse in question. If it was in the freezer, let it thaw for a few hours, until there are no more cold spots. But not too long, or the insides will start to spoil.
You will also need a small piece of cardboard, to pin your mouse down to later. I didn't take a picture of this, you all know what cardboard looks like, don't you!?
YOU SHOULD ALSO WEAR GLOVES DURING THIS PROCEDURE. FOR YOUR OWN SAFETY!
STEP 1
Place your mouse on it's back, on the cardboard piece you have chosen. Carefully pinch the skin up on the mouse's chest (at the red dot) and with your other hand, work the tip of your blade CAREFULLY beneath the skin, and begin CAREFULLY cutting downwards, with your blade facing UP. You do not want to puncture the abdominal cavity at this point. If the mouse is a male (like this one), you can cut slightly off center to avoid his penis and testicles, and cut nearly all the way to his anus. Once you've gone that far down, carefully slice the skin from the initial incision, up to the throat.
STEP 2
Your mouse should now look like this (minus the red arrows
):
Carefully grasp the skin by the points indicated by red dots, and peel it away from the mouse's carcass. It should peel back very easily. You CAN use your blade for this, but you may end up cutting through the skin, if you are not skilled in this.
STEP 3
Your mouse should now look like this:
Carefully pull the skin away from the body, and tack it to the cardboard at four points, making it into a neat square, or rectangle.
STEP4
Your mouse should now look like this:
If anything about this would be hard, this would be it. The blade you are using MUST be extremely sharp, or you will end up puncturing something you don't want to. If you are using an exacto knife with an old blade, now would be the time to get a new one. CAREFULLY cut the membrane on the breast bone, and continue downwards (pinching the membrane between your fingers, helps keep it tight and away from the internal organs) until you reach the mouse's anus. Then, carefully cut the membrane down the sides (where the lines indicate) and peel it away from the guts.
STEP 5
Your mouse should now look like this:
Here you can see most of the organs. Things like the heart and lungs are up inside the chest cavity, so if you need to check them, just carefully pull out the other organs. One by one is usually best, so as not to get everything messy. The kidneys are under a few things, but are very recognizable. This is a male mouse, so you can see his testicles near the bottom.
I'm not going to go into more detail, and take out each organ at the moment. This is just to help people get started. If you were looking for a cancer, it should be easy to find.
This mouse suffered from obesity. After I did the autopsy, I fully skinned him, and took the fat off of the carcass, for reference. This mouse was pretty large, and it only took the small amount of fat you see here, to cause his problems:
It helps put things into perspective. You'd figure there would be more fat, but no.
If you do an autopsy, and find something that you think is abnormal, but cannot identify, feel free to post a photo here, and we will try to help you find out what was wrong. If we cannot help you, the best thing to do would be to freeze the specimen that you found, and give it to your vet for a better diagnosis.
I hope this can be beneficial to people, and educational. I know, it's not pretty, but it's life, it's science, and it can help you to better understand problems when they arise in your other, living mice.
Thanks. I hope this helps you.
