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I am NOT a vet, I am not an animal researcher. I am a loving rat mom and responsible breeder who has researched these health issues. I encourage everyone to always research yourself, consult your vet and use your instinct to decide what is best.

This is a bacteria that every single rat has. (Some lab rats do not carry myco because they are delivered by c-section in sterile lab environment. The moment they come in to contact with rats with myco, they will catch it.)

It is highly contagious but It is host specific meaning you or your other pets can not catch it. Myco likes to hang out in the respiratory tract and wreak havoc there, so this leads to upper/lower respiratory infections which often can be chronic.

It is important to note that Myco flairups can also be brought on by other infections that are very serious and can be deadly such as CAR, SDA, Sendai, etc…

The issue is not exactly the Myco itself, day to day normal life of a rat it is not going to be an issue. It is the Myco flair ups that cause respiratory issues that are the problem.

Let’s say you have a large jar and every single day I give you a marble. And throughout your entire life, if I gave you a single marble every day it would never fill the jar. Yay! (it is a big jar and you don’t want it filled).

But every time you got really stressed, or sick or had some environmental issues, etc… you got a whole handful of marbles!

The more it happens the faster your jar fills up so that when you are older your jar ends up being filled and overflowing. For others who started life weaker or had other health issues their jars were already way small to begin with.

While not exactly the same, this is often what happens with Myco. These bacteria are slowly building up through the rats life. These babies may appear perfectly healthy but inside of them is not… and you end up with a rat (sometimes even just over 2-6 months!) that is getting chronic respiratory issues.

Note: New home sneezes and the occasional sniffle.

It is very common for rats to have sneezes when first going to a new home. This is just them adjusting to all the new scents. I want to see them disappear during the first week. It should be dry and not getting worse or coupled with other symptoms. As well an occasional lone sniffle here or there is fine. Something just in the air perhaps. Just watch to see if it gets worse or coupled with other issues.

Why Good Breeding Matters?

So if every rat has Myco what does breeding matter? Well itt actually does a lot!

It all starts with momma (and the lines that made her that way). You want a strong healthy mom that is the proper age/weight to give birth. She is giving birth to a whole litter of babies and being their sole source of food for atleast the first 2-3 weeks of life, which is a HUGE important time for proper growth and health of the babies. Moms need to be able to produce enough healthy milk to feed all of her young. She also needs to be able to do so without losing a lot of form, ie mom should be able to stay a good weight and healthy throughout the pregnancy and nursing.

This is going to start off every one of those babies with a healthy good foundation for the rest of their life. These babies will grow properly and strong. They will be better suited to not only be more resistant to illness but better equipped to fight it off. 

Stress plays a large role in Myco flair ups as well. How rats are affected by stressful situations depends a lot on their temperaments and anxiety levels. Temperament/anxiety are both largely genetic. You want a line/mom that has beautiful temperaments to pass that on to her babies. There is also the lick a rat study that has proven that good moms can make for less anxious babies. You have a good mom who has a great temperament and is not an anxious stressed rat herself, she will then take better care of her babies and groom/lick them more. This actually changes their DNA making them less anxious rats and it sticks with them for life!

Good breeding also focuses on not breeding rats that are prone to illness or have health problems. Always choosing the strongest, healthiest rats means you can create rats that are more resistant to Myco . Many breeders also do things like cull litter size, less babies mean an easier time for mom and bigger fatter healthier babies. Mom can properly feed each baby to their full potential and spend individual time grooming and caring for each baby more.

Sadly mills and BYBs often pull babies from mom far far too early, leave them over crowded and stressed and do not care about bettering lines and breeding for the very best health/temperament, they only have to be good enough. As most myco flairups happen later in life or only come about when coupled with environmental factors it is easy for these mills to not care.

Prevention: What you can do at home?

Good breeding will make rats less prone to stress and illness but not immune. Their environment and home life really matters!

Practice good husbandry. Keep your cages clean clean clean!! One of the biggest issues is ammonia buildup. People don’t clean their cages often enough or use the wrong type of bedding.

Bedding is hugely important. Do not use cedar, paper bedding has been shown in studies to be absolutely horrid and unsafe at properly controlling ammonia levels. Fabric bedding also does absolutely nothing at neutralizing ammonia. I highly suggest never using fabric unless your rats are litterbox trained fully.

Have a good size cage that is not over crowded. This prevents the need to clean as often and it prevents stress to the animals. Your cage should also be very well ventilated.

Don’t have the cage located in drafty areas, don’t have the cage outdoors, and try to control the temperature of the room they are kept in so it is not too hot or cold.

When using fabric (even just for hammocks) pay attention to the type of soaps you wash it in, scent free is key. I would also suggest using a sensitive formula, the ones made for babies are great. Do not use fabric softener.

Environmental irritants play a major role. Do not use air fresheners or sprays or anything strong smelling. Do not light incense or burn candles. I make candles myself and by far most wicks are actually very toxic (even to us). While cheap candles often can be scary with how bad, even expensive well known brand candles can have toxic wicks. Just don’t light them.

I hate that I ever have to even say this but- DO NOT SMOKE IN YOUR HOME IF YOU HAVE RATS (OR ANY PET REALLY!!)

Quarantine new rats. There are so many illnesses out there and not only can your current rats catch it, it can also cause flairups.

Treat symptoms early. Don’t have a wait and see attitude. Respiratory issues can cause damage to the lungs. Again this is a chronic issue, think of the marbles. This is often why people have issues with it not going away completely or it keeps coming back. And also know that there are other infections out there that can seem like a Myco flairup but actually be far worse and deadly like I said- Sendai, SDA, Car, etc…


The health of my lines:

I only ever breed healthy rats. If my rats get sick I will retire them on the spot. I want strong healthy resistant rats. Many of my lines are new to me but they all come from established well known great breeders who I trust to breed healthy animals.

I work very hard to make sure the environment for them is safe and as healthy as possible.
I have safe quarantine practices.

As of writing this (July 6th 2017) I have only ever had one respiratory issue in my bred rats. It was with one of my first litters and he was in a traumatic incident. The rat was not injured but the experience was extremely stressful for him. He got very sick and did not recover. I still miss him very much :(

I have been quite blessed and that coupled with great care has not caused me any issues so far *knock on wood*

More info:
Mycoplasma on RatGuide:
Lick a rat study:

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