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African Soft-Furred Rat

 

 

Praomys Natalensis, Praomys (Mastomys) Natalensis, Mastomys Natalensis, Natal Rats, African Soft Furred rat, African Soft-Furred Rat, Multimammate Mice, ASF's, ASF rats


Praomys Natalensis - African Soft Furred Rats are quickly becoming a favorite as feeders for small to medium sized snakes, birds of prey, and carnivorous lizards and amphibians. Their small adult size compared to the Norway rat makes them ideal to keep, because they are often the perfect feeding size for months and will not outgrow the feeding limits for most carnivores like a Norway rat will.

They thrive in polygamous colonies, most often consisting of one male and three to five females. If you want to start breeding African Soft Furred rats, make sure these animals are not illegal to own in your state. (Link to small listing of US breeders)

They are a serious pest in most of sub-sahara Africa and it is economically the most detrimental rodent pest to crops and farming. Many states in the US found it appropriate to ban the ownership of these rats based on this and other facts associated with Praomys Natalensis. This is most common in southern and western states of the US.

They are widely used in the scientific community to study diseases that are also common to man, like degenerative joint disease, renal disease and carcinoid tumors of the stomach.

The confusion with the names, as far as I can see, is outline from this article "Because of controversies many years ago, Mastomys was never phylogenetically classified as a genus, but remains a subgenus, designated Praomys (Mastomys) natalensis." found here http://www.ncbi.nlm.nih.gov/pubmed/6197364

Since they are still commonly referred to as Mastomys Natalensis, be sure to use both search terms when trying to find information about these animals.


Basics

Scientific Name: Praomys (Mastomys) Natalensis, (Mastomys Natalensis may be an outdated term)
Common Name: African Soft Furs, Natal Rats, Multimammate Rat, (Mice is an outdated term)
Average Lifespan: 2-3 years in captivity
Adult Weight: Males: 100- 130g; Females: 90-115g
Litter Size: 3-17;  average is 9-12 per litter. Will decrease with age.
Sexual Maturity: 54-63 days
Gestation: 21-23 days
First Litter: Approx 3.5 months of age. Will be bred again within hours of giving birth.
Menopause: Approx 12-15 mo. of age.
Note: African soft furs cannot reproduce with a rat or mouse.


 

Table of Contents


Introduction: First experiences and rumors

Colors: Agouti Amber

Cinnamon Ruby Eyed
Patterns: Self Head Spot

Pied High White (Extreme Pied)
Habits: Handling Chewing

Stress Activites Wheels
Illnesses: Lameness Tumors and Warty Growths


 


 

 

Introduction to ASF Rats

 

I had the opportunity to buy a group of these amazing little rats back in the end of March 08. I purchased a group of one male “pied”, and two females, one female being an Amber, and the other a Cinnamon. I, of course, immediately named them, Gabbagoo, Cherry and Ginger.

I spent some time just observing these guys in their new home. They were pretty jumpy and easily startled. When picked up, they would try to jump straight off my hand without even batting an eye. It was amusing to see, but also a little nerve wracking. They never attempted to bite me (in the first few weeks), but they did pee on me quite a bit while I handled them. They were so interesting and a lot of fun to watch.

I continued to handle them about once a day. The first time I got bit it didn’t draw any blood, but it did hurt like hell and was a little rough for such a small sized animal. From then on I let them do their own thing and understood that my little family of ASF's were growing up and didn't care much for me trying to hold them.  I did interact with them daily to keep them used to me, but I didn’t bother to hold them like a pet rat anymore. They continued to go on with their lives. Their first litter from both females was 16 and 15 each, both born within a day of each other. I was thrilled.

I fed them off every week to my snakes, and out of 40 something snakes, only one girl shows any sort of preference and will ONLY takes ASF’s. It actually seems that most of my snakes prefer regular rats.

If you’ve heard about these animals, you would probably have been told a few key things about them.

•    They don’t outgrow Ball Pythons.
•    Ball Pythons LOVE THEM.
•    They don’t smell as bad as Mice or Domestic Rats.
•    They breed prolifically.
•    They BITE!!!

While there is debate that ASF's are the cure-all for non-feeding ball pythons (out of my 40+ snakes, very few will regularly take ASFs at every meal), they are a really good size for a ball python and other animals that need whole prey animals.

I do want to clear up a prolific myth: African soft furred rats are not "odorless".

While I used to see these claims around the reptile forums, they are not odorless. They certainly have an odor. When I started working with these ASF rats, I actually found their odor quite nauseating and overpowering. Is that normal? Many would say no, but they do smell, and anyone who says differently either does not have a keen sense of smell, or does not have more than one or two groups.

In short, for some people, the odor from ASF's is not as offensive as it is for others, but they do have an odor. Let’s just make that clear right here and now.
 


These rats REALLY enjoy sitting in bowls

Colors

 

 

Agouti

 agouti2 agouti3

This is the wild type color and pattern. Much like the Domestic Norway Rat, the hairs are banded Agouti. The animals appear a dark gray color when young, and lightening to a dark brown color as an adult, with a cool blue belly. Eyes are black, ears are pigmented dark. When young, the animals appear almost black, but as they age, the yellow banding will show up more prominently, especially on the sides of the animal.

 

Amber (not albino)

 amber1

Also like the Domestic Norway Rat, the Ambers are a bright orange-yellow color. The best way I can describe them is the Pink Eyed Dilute on an agouti striped hair. The eyes are a rich pink color. The ears are not pigmented, also being a light pink color. Undercoats are blue on the wild type agouti color,  Amber on the cinnamon creates a richer yellow color lacking the blue undercoat (Argente in Europe).

 

Cinnamon

 

This animal is a light brown color on an agouti hair. They are almost a light bluish gray color when young. I think this is much like the Red Eyed Dilute of the Norway Rat. The eyes do appear to be a dark brown color, almost black. They have a blueish tint that is starkly apparent when young, and will get a bit darker and browner as they age. It is a simple recessive gene. It is different than the Ruby Eyed gene, but can be incredibly hard to tell the difference from a Ruby eyed unless eyes are very bright red. (Updated 2/17/09)

 

Ruby eyed

I have confirmed in a few different litters that the Ruby Eyed is a different gene than the Cinnamon. I bred specifically a Cinnamon Pied female to a Ruby Eyed Self male (pictured above). The offspring would all have the head spot, because each would be heterozygous for white spotting because pied is homozygous. The litter consisted of the lighter Cinnamons and Rubys (difficult to tell apart when very young), a couple of Ambers, and one Agouti.

Since each parent animal is homozygous for its trait, we should have gotten all Cinnamons or Rubys to prove it was the same gene. Since we got one agouti, they are not the same gene.
I am certain that the Ruby Eyed and Cinnamon are in fact two different genes at work. They also appear to both be a simple recessive.
 

   ruby-agouti

It is likely there will be a non-agouti (no yellow banding) animal found and reported someday, if not already known by a select few. Once these animals are found and bred, we could get a lot more colors like the Norway Rat has.


 

Patterns- Isn’t a Pied a ball python?

ASF rats are used mainly as feeders for reptiles. This means that many breeders have given them very reptilian names to describe the colors and patterns. Some people call Ambers “Albinos”, and some people call the white spotted “Pieds”. I’ll try to match this to some fancy rat terms, but I do like the word Pied and can’t think of anything similar from the rat fancy world.

Self

This animal is just what the name says. It is lacking any white spotting on the body. Belly is a lighter color, but not white.

Head Spot (White spotting, heterozygous form)

This animal shows a head spot, it can be short or long and almost like a blaze on a horse. Sometimes these animals have white jaws and necks, but the white on the jaw does not connect to the white on the head spot except by the tip of the nose. Belly remains the lighter color and may have white spots or striping. Rump near tail may also have spots and a more defined head stripe. This gene seems to quite variable in strength, as some have very little of a head spot or stripe, while other animals can have a very strong and wide head stripe. They may also be referred to as "Gremlin", though it’s a very uncommon name.

head spot

Pied (White spotting, homozygous form)

The pied is an animal with a white head, and a white rear end. The white spotting can leave a small “cape” near the base of the neck covering the shoulder blades or can be as little as to touch just the base of the tail with some spots of white. The heads usually have a characteristic “Eye brows” pattern, and some symmetrical spots or stripes on the cheeks or side of the face.

The white spotting gene has variable strength. Animals can have a completely white head with no markings, or have quite a few dark spots on the face.

The edging of the color is hardly ever straight, often with intermittent spots of white and color giving a very checkered, piebald pattern. They are sometimes also referred to as "Caped" or "Check[er]" in Europe, and as "panda phase" by some folks in the US.
 

 

Extreme Pied (AKA Black Eyed White)

This animal is the work of very selective breeding. Pictured below are the animals from two different breeders in Germany. The dominant Pied gene has been worked for generations to create an animal lacking almost all colored areas, except for the ears and a few random spots on the back. In Germany, I believe they refer to Pieds as Check[ers]. These are available in the US from some breeders. This is a reply I received from one of the German owners.

Translated, roughly:

      "My white VZM are only selectively bred checks 😉 Unfortunately no real BEW."

So there you have it! The work of scrupulous selective breeding. (Platinum in Europe)

Check out my interview with Stefan K. about his gorgeous high white ASF's.

http://www.metalmonkeyexotics.com/blog/?p=3106

High White


(Pictures used with permission by M. Richter of www.blausucht.de)

Agouti and Cinnamon high white ASF Amber high white asf Cinnamon high white asf
(Pictures used with permission from Stefan K. from ratfrett.jimdo.com)

 

 

 


Rat pups squirming in a pile

 

Habits- Those things are nutso!

Handling

The common demeanor of the US animals is defensive and often aggressive. I can't say if the same is true for Europe, since in Europe most Fancy Rat breeders really try for companion animals and work towards a less bite prone, nervous animal.

It is possible with constant interaction to get individual rats used to human handling and even playing with you, but this takes almost daily handling and working with the individual animal. There are ASF's that are more curious and easily worked with, but in the US, that can be few and far between.

If you do want to keep these animals as companion pets, remember that it will be difficult, but not impossible. I suggest buying a very young animal from a breeder who knows that their animals are not as likely to bite as other breeder’s colonies, and when you get these animals, get the same sex so you never breed them. ASF's are very protective of their young and their relaxed behavior with you will change as soon as those pups are born. It can take a long time to get them back to a relaxed animal.

As with Norway rats, the males tend to be more relaxed, where the females are more high energy and stress easily.

When you want to start the handling, keep the sessions short and positive. DON'T stop when they bite. This reinforces that biting behavior, because it teaches them that they can bite and are left alone. Keep the sessions short and positive, and slowly work up to longer sessions. I can't reiterate this enough.

Bring them small treats like a dog biscuit, seeds, yogurt drops, raisins, and work with the animal a few times a day, so they learn that you are safe, and even bring them yummy treats!

When you first start working with them, you may notice they hold completely still and close their eyes. This is not enjoyment. Almost never do ASF's enjoy human interaction right away, and this behavior is more of a sign that they are stressed.

For more reading on keeping ASF's as pets, please visit the following link.
http://mouse-agility.com/asfrats.htm

Chewing

ASF rats are high energy compared to regular rats. They almost always need to be doing something. Whether that’s chewing shavings, shelling seeds, gnawing whatever they can get their teeth on, these little guys have motor mouths that need to be busy almost all the time! Since I’m not sure if their teeth grow exceptionally fast, it’s still a good idea to give them something to chew to prevent problems and ultimately starvation and death.

These animals will chew whatever you give them. Cuttle bone, untreated wood blocks, their plastic hides, cardboard tubes, hardware cloth, you name it. I used to give my rats untreated wood blocks. The blocks are long 2x2’s cut into 4” lengths. They lasted quite a long time, and once they become small little pegs or stained orange yellow from pee, they were replaced.
 

Crumbling Food

Another strange thing I have seen them do is crumbling their food. I first read about this from someone on a forum, and I wasn’t entirely sure what they meant. They referenced it as “turning their food to dust.” It was a strange idea to me, but I have seen it with my own eyes now, and I know exactly why my animal had done it.

I just removed a male from his breeding group. I no longer needed them to produce and put him into an empty spare maternity tub. He had access to wood, food, and water all night. When we checked on him the next day to move him in with the other males, we had noticed that most of this food was gone. That was about a pint of food in the rack for him. He did not have direct access to remove pellets, since they sit on top of ½” hardware cloth. He had chewed up all of his food into little crumbles, and didn’t eat any of it.

The crumbles looked like chick feed. It was such a waste. We speculated that the stress of being removed from his breeding group was overwhelming for him, and he had to release the stress some way.
 

Wheels

I have given my rats wheels. I think that giving them an enriched environment will curb their desire to chew on the enclosure or fight with one another. I have also offered a small portion of seeds and Timothy hay once a week, I have given treats like hard dog biscuits, and offered wood blocks. They have had hides, easy to reach water and food.

I no longer offer all of these extras to my ASF rats. They get wood shavings, food, water, and the company of their colony mates. I decided to stop offering these extras when all the rats were doing was sleep on the wheels, and pee on the wood rather than use them for their intended purpose. They've done exceptionally well without the fluff.

ASF’s love wheels. They use them like it’s their reason for living. They pile on, 4 or 5 at a time, some hanging on for dear life on the outside as others run on the inside of the wheel. If you take their wheels away, initially they are highly stressed and destructive. In return I gave them a bunch of things to chew and destroy including very thick cardboard tubes, seeds, wood blocks, dog biscuits, and also many types of paper products to shred, since we all know how they freak when we take away something they depend on for stress release.

If rats are fighting or scuffling, you will often see the rats involved jump onto the wheel and run. I believe it’s their way of dealing with the stress.

If you don’t want to provide wheels to your rats, then I highly recommend you never introduce them.
 

               *A note of caution* about wheels...

I have gone through quite a few wheels for these buggers, and the only ones we have available in local pet shops are the powder coated (painted) metal wire wheels.

The rats chewed off the paint on a few of them, and in those tubs the wire of the wheel rusted pretty easily and one of them developed sores on the bottom of his paws.

If you are going to consider giving them wheels, avoid any powder coated (painted) wheels, but go for nickel, chrome, or plastic wheels that have a lot of clearance on the sides to keep little tails and legs from being broken.  (Example: Prevue Hamster Wheels 7" are made of Nickel and will not rust)
 

Illnesses

Nervous System/ Muscle weakness (possibly hereditary)

I discovered a disease in my colony. I am always curious about the genetics with rats, and I bred my original male to two of his daughters. I know that he was from a different source than the two original females I purchased. I found problems to originate in the original father through line breeding. It does seem possible to breed away from this issue through outbreeding with other rats from different sources.

The best way I can describe the problem is that the rats extend their legs at the hip joint, splayed straight out sideways instead of underneath them to walk. Some are more affected than others. The very badly affected ones use their front legs to drag themselves around, or will actually roll sideways where they want to go.

It is only really noticeable in their back legs. They have very poor muscle control; however they can crawl/drag/roll around the cage although it is very sad to watch. If no precautions are taken (lowering water valve and food hopper) they will perish. Loose bedding is not recommended because they use it to push around the cage, and too loose of bedding will make it harder for them to get around.

I haven't had any of these rats die from abuse in the colony, and I actually leave them with the mothers until they reach a bigger size; due to their condition they grow much slower than their non-disabled siblings.

Update 8/11/10: It has been a few years and several generations later, besides the initial father and daughters bred to each other, I have not seen another occurrence of the problems, and I have line bred several colonies of animals to be sure of it.
 

 

 

Tumors

ASF's are prone to spontaneous, fast growing warty tumors. From reading various papers, the warty and ulcer like tumors known as keratoacanthomas and squamous carcinomas, are associated with a papillomavirus (MnPV). The tumors can be seen in the vaginal region as a clustered mass, along the tail as bumps, on the back and hind quarters as warty black growths, or on the face of the animal.

Pictures can be found here

They will develop warty tumors, patchy hairloss, and osteoarthritis as they age past approx 9 months, although it can be younger, or delayed as much as 14 months. And sometimes, not at all. 

So far, it would seem that the tumors develop after 9 -12months of age, although not all will get this condition. I had at least one Amber colored female not develope any tumors until close to her second year.

The tumor development can be very fast and spontaneous. I've had one female that within days developed fast growing tumors all over her body, under the skin and on the skin surface. I should have taken a picture, but I didn't remember to before she was euthanized and destroyed. It was disturbing to see the alarming rate that the tumors grew, she had just reached approximately 8-9 months of age when these tumors/warts developed.

I suggest keeping rats for at least 9 months of age and hold back animals from colonies that are less susceptible to the tumors.

They are also prone to stomach cancer, which is one of the main reasons these animals are used in research.

You can google "squamous cell carcinoma mastomys natalensis" and read a lot of articles (some you have to pay for) that discuss the virus and the cause of these tumors. (I have linked to many articles at the bottom of this entry)

 


These are all just my own experiences with my ASF rats, and like I say all around the forums...

THESE THINGS SMELL AWFUL!

Joking aside, we've put a lot of work into each piece, and want to remind everyone that if you like what we do here, please make a link back to this page, rather than infringing on copyrights.

We wouldn't steal your works, please don't take ours. Thanks for understanding! 😉

     avatar  :: Connie

 

Continue on to:

 

   
 

Breeding African Soft Furred Rats

Or

African Soft Furred Photo Gallery

 

 

Informational Sources

For more reading on keeping ASF's as pets, please visit the following link. 
http://mouse-agility.com/asfrats.htm

If you would like to find ASF's near your area, this webpage has a small current listing of ASF breeders.
http://www.sapphiretigress.com/Softfurs.htm (no longer available)

If you are looking for ASF breeders in your state, follow this link.
http://asfrats.info/viewforum.php?f=8& (no longer available)

Or you can visit the ASF's breeders and information exchange forum
http://asfrats.info (no longer available)

Russell Toft's Article on ASF's (A good read, although may be outdated.)
http://homepage.ntlworld.com/jean.wright93/mm/mm.htm

Thames Valley Rodents
http://www.freewebs.com/abcexotics/multimammatemice.htm

Batwrangler.net (a small listing of personal blogs, a great source of technical information)
http://www.batwrangler.net/multimammate/ (no longer available)


 

Ken-ichi Mafune, Kaiyo Takubo
The diversity of gastric carcinoma

http://books.google.com/books?id=DEq...snum=9#PPA4,M1

Tan C H; Tachezy R; Van Ranst M; Chan S Y; Bernard H U; Burk R D
The Mastomys natalensis papillomavirus: nucleotide sequence, genome organization, and phylogenetic relationship of a rodent papillomavirus involved in tumorigenesis of cutaneous epithelia
http://www.biomedexperts.com/Abstrac...nship_of_a_rod

Rudolph R, Müller H
Induction of epidermal tumor growth in the skin of Mastomys natalensis by transfer of virus-containing tumor tissue from a squamous cell carcinoma
Zentralbl Veterinarmed B. 1976 Mar;23(2):143-50. German. No abstract available.
http://www.ncbi.nlm.nih.gov/pubmed/1266439

HERMANN  MIULLER,  AYD  LUTZ  GISSMANN
Mastomys natalensis  Papilloma Virus  (MnPV), the Causative Agent  of Epithelial Proliferations: Characterization of  the Virus Particle
http://vir.sgmjournals.org/cgi/reprint/41/2/315

K. Wayss, E. Amtmann, G. Fürstenberger, G. Sauer and M. Volm
Tumorpromoter modulate skin tumorgenesis induced by papillomavirus in mastomys natalensis
http://resources.metapress.com/pdf-p...2&size=largest
http://www.springerlink.com/content/lg3430177178j132/

J. Nafz, M. Ohnesorge, E. Stockfleth, F. Rösl and I. Nindl
Imiquimod treatment of papilloma virus and DMBA /TPA-induced cutaneous skin cancer in Mastomys coucha: an unique animal model system useful for preclinical studies
http://www3.interscience.wiley.com/j...84058/abstract
http://pt.wkhealth.com/pt/re/bjdr/abstract.00002300-2

Manfred Reinacher, Hermann Müller, Wolfgang Thiel and Roland L. Rudolph
Localization of papillomavirus and virus-specific antigens in the skin of tumor-bearing Mastomys natalensis (GRA Giessen)
http://pt.wkhealth.com/pt/re/bjdr/ab...195628!8091!-1
http://www.springerlink.com/content/pw8826314054212w/

Julia Nafz, Anja Köhler, Myriam Ohnesorge, Ingo Nindl, Eggert Stockfleth and Frank Rösl
Persistence of Mastomys natalensis papillomavirus in multiple organs identifies novel targets for infection

http://vir.sgmjournals.org/cgi/reprint/88/10/2670

Iris Helfrich, Min Chen, Rainer Schmidt, Gerhard Fürstenberger, Annette Kopp-Schneider, David Trick, Hermann-Josef Gröne, Harald zur Hausen, and Frank Rösl
Increased Incidence of Squamous Cell Carcinomas in Mastomys natalensis Papillomavirus E6 Transgenic Mice during Two-Stage Skin Carcinogenesis
http://jvi.asm.org/cgi/reprint/78/9/4797

Robert K. Jackson (have to scroll down to Mastomys)
Unusual Laboratory Rodent Species: Research Uses, Care, and Associated Biohazards
http://dels.nas.edu/ilar_n/ilarjourn...1Unusual.shtml

Klaus Wayss, Denis Reyes-Mayes and Manfred Volm
Chemical carcinogenesis by the two-stage protocol in the skin of Mastomys natalensis (Muridae) using topical initiation with 7,12-dimethylbenz(a)anthracene and topical promotion with 12-0-tetradecanoylphorbol-13-acetate
http://www.springerlink.com/content/w5222w4581321370/

Anton J. Bilchika, Ola Nilssona,  Irvin M. Modlin, Karl A. Zuckera and Thomas E. Adrian
Significance of gastric endocrine tumor and age-related gut peptide alterations in Mastomys
http://www.sciencedirect.com/science...f533d0be858763

J. D. Randeria
Animal model: carcinoids and adenocarcinoma of the glandular stomach of Praomys (Mastomys) natalensis.
http://www.pubmedcentral.nih.gov/art...?artid=2042366

Keniti KOZIMA, Takeshi MUROHASHI, Jun SOGA and Kenji TAZAWA
HISTOLOGICAL AND IMMUNOHISTOCHEMICAL STUDIES ON SPONTANEOUS RENAL LESIONS OF PRAOMYS (MASTOMYS) NATALENSIS
http://www3.interscience.wiley.com/j...TRY=1&SRETRY=0

K. C. Snell, H. L. Stewart
Spontaneous diseases in a closed colony of Praomys (Mastomys) natalensis
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2366624/

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