Blog Archives

Great Things Come in All Sizes of Litters

10/23/2017

A common post I often see on social media is,

“I have a small baby in this litter, could it be a dwarf?”

Most likely not. If the baby has always been small, hitting all the milestones as it’s litter mates, such as pigment showing around same day and eyes opening, you most likely have a runt on your hands. Often a dwarf rat will not slow down in growth until around weeks 3 - 4 in an average litter. (It was recently brought to my attention by someone that had a smaller litter that their difference was more obvious much earlier.) Sometimes you won’t notice a runt until the first week passes. Sometimes there are more than one in a litter. Runts will often catch up to their litter mates by weeks 9-12. However, if you have a little one that is skinnier than it's litter mates, lagging, not hitting their milestones, you may have FTT (Failure to Thrive also known as 'ill thrift' by veterinarians.) They are often very skinny and weak; not able to absorb all the nutrients needed to meet those milestones. Most often FTT will not survive into adulthood. Either the mother will push them out of the nest, sensing something not right, or they will pass on their own before 2 weeks. There are exceptions, my 939 gram boy, CRUS Bennet, being one of them. He was FTT, ½ the size of his siblings and too weak to be able to push them off so he could nurse. If his breeder didn't make sure he latched on and supplemented him with extra formula he most likely would have never survived past 2 weeks. He was one of my biggest boys and lived to just shy of his 2nd birthday.

As with CRUS Bennet (mentioned above), I have become known as 'The Collector of Runts'. I have a soft spot for the lil guy in a litter. This is simply as a pet lover, not a breeder. Wanting to keep runts or adopt runts from others, fills up the mischief rather quickly. This limits my space so I am not able to work with all the varieties I want. Often a breeder will have what they call a 'bucket list' of rats they would like to someday work with. My list of those that I would like to someday have would include: Harvel, Roan, Whiteside, & Rex. I also love a beautiful Self rat. (All one color). I am trying to get the pigment of my lines all the way down to their toes. There will sometimes be an odd recessive blaze, or variegated popping up, keeping the litters even more entertaining. The most recent marking surprise in a litter happened at the end of last year, in the 2016 Winter All Science Litter, appearing at 4 ½ weeks. OCRA Inertia was our very first Himalayan and OCRA Tesla ended up being a beautiful Burmese! Up until she showed up, I had never even seen a Burmese. WOW! I must say, my favorite look for sure. Currently we are working with Standard & Satin coats in Burmese, Himalayan, Siamese, Mink, Russian Blue, Agouti, Blue, Chocolate, Black and all of their dilutes. I also loved our pets that were Hairless and enjoy the Drex but do not want to work with those as a breeder. Hairless often have lactation issues that would mean doubling up on my breeding so I would need a foster mother for the babies. With my 2 Drex rats that I love as pets, I have found a lot of issues such as the eyelashes growing wrong and extra pory due to the irritation. The constant shedding from coarse broken hairs also drives me batty but they are worth it. I love them dearly.

So back to the dwarf question mentioned above. Did you notice dwarf was not mentioned on my bucket list? Never in my wildest dreams, had I thought I would work with dwarf. This is a tough variety to work with. The babies are often the same size as standards so a dwarf mama could have difficulty birthing. For the female dwarf that do deliver, their litters are much smaller than the standard litters in number. Often 3-6 verses 8-15 with a full-size rat. Talking with other breeders, the best option would be to breed dwarf carriers or a dwarf male to a carrier female. Even then, you are not guaranteed dwarf when working with carriers. Why all this talk about dwarf? Well.... because of our Burmese, OCRA Tesla, in the 2016 litter, we wanted to pull more Burmese out to work with. To do that we bred her back to her father OCRA Galileo. Imagine my surprise when our 2017 Summer All Science Litter v2.0 hit 3.5 weeks and 3 boys (OCRA Tesla’s Coil, OCRA Electron and OCRA Luman) slowed down. I mean WAY DOWN in their growth compared to their siblings. First thought was FTT and I hit a bit of a panic. I began supplementing them with extra goodies hoping to get them back up to their siblings’ weight. All they ended up doing was getting round. As they hit 5.5 weeks old their weigh difference was ½ their siblings, 70-79 grams verses their siblings at 140-160 grams. They continued to grow and be VERY active. Now at 5 months they weigh 132-180 grams and their siblings are over 560 grams! The two that are heavier are VERY round still but in every way, look like dwarf – looking at their little bellies they are about 25-35 grams overweight. They all live with standard size males with no issues. Well, except for the Napoleon Syndrome they seem to be expressing (in fact one was renamed Napoleon by his adopter). It is amazing when you have a litter of 12 thinking you are just working with your standard line and you get a surprise. We have no idea where they came from, since I can track my lines back to 2010 with one other breeder, 2012 & 2013 with another. I may never know where the recessive dwarf came from but will have a lot of fun testing it out with another proven dwarf to see how this new line will develop. Here is a link to the album on fb so you can follow our dwarf adventure with OCRA Tesla and her next litter!

*Male and Female rats really differ in their weight after 6 weeks, for the graph I combined the averages of both. **Dwarf weights are from breeders in the area: Little Diva's Rattery, Sith Rattery, The Breakfast Bunch Rattery, & Kobold Rattery ***Runt Weight is combined from Our Crazy Rat Adventure tracking of 15 different litters ****Several of the adult dwarf are overweight (15-50 grams) – after talking to many breeders apparently this is a common issue with them.

More info on Dwarf:

Study of growth hormone in spontaneous dwarf rat

Great pictures for comparison

More information on dwarf rats

Why all this information? Is it simply to talk about this amazing discovery in our mischief? No, it is to explain growth of babies and their hidden potential. A few breeders do not like their litters to be more than 6-8 in number, sometimes even smaller. Their theory is that it will be easier on the mama and their babies will be nice and FAT. To achieve this there are a few things they will do. If they have another nursing mom they may place a few with her. Otherwise, they may hard cull (kill) certain babies depending on size, eye colors or wait until a bit older for pigment to show before they hard cull those colors that they do not want to work with. Often the breeders that do this are multipurpose breeders as well, called Feeder Breeders. They breed to feed animals for other owners and their own pets. Though I can't imagine doing this personally, I accept that other animals need to eat. Unfortunately, some breeders that do not have to feed other animals, will still hard cull down their littler size simply because they think it is the only way to get fat healthy baby rats. I have chosen not to do this, after years of tracking their weights, I feel confident that our females have done a fabulous job with their litters no matter what size. Mama's should always keep their weight without struggles and bouncing back to post pregnancy weight by weaning is an important goal I have for all of the mama's. Over the years, there have been a few times I have had to increase fat offered in hopes to help with dryer skin in the babies. Another time, we did need to give mama a bit extra from the beginning – she had 18 babies! Over the years a baby has passed in the first few days and only a few times have we lost one after the first week. It is a very difficult choice to have babies euthanized. One had an umbilical hernia that did not get better and another that had a skull injury. Both of those became FTT due to their injuries. We also lost on baby to megacolon (in a line I immediately took out of my program). After several years of breeding and tracking weights weekly, I have shown that the babies of larger litters (up to 18) have all gained and are around the same size as those of litters that are as small as 2. In fact, some of my smallest babies were from a litter of 2. Their genetics were simply for a more petite rat. Thankfully we allow our litters to develop naturally, if we didn’t, we may never had known about our Burmese or the Dwarf Boys.

Below are a few interesting things I have found online about overweight babies and basic litter size. (Warning some of the scientific studies can get graphic in their descriptions of their testing and how they cull) Often in scientific studies they will want to have same numbers of offspring and equal sex ratio to help them get to the outcomes for their studies. As a pet breeder I do not see the necessity to do this. Though I love a squishy fat baby, I do not want to simply focus on having equal sized litters to have the fat babies but rather overall healthy babies thinking of the long term health of the rat.