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Thursday, May 28, 2015

Efficient Layout for Cutting CN Liners out of U-Haul Furniture Pad

I have been making cage liners for the Critter Nation from U-Haul furniture pads for a while now. I know that one furniture pad is enough to make all the liners for two dual Critter Nation cages, minus one shelf, but only if the pieces are laid out efficiently. Unfortunately, I keep forgetting how they need to be laid out.

So today, I decided to take a picture of the proper layout so that I can remember how it goes in the future. Note that the bottom and top levels are the same dimensions (except for the cutout), so they are completely interchangeable. Also note that you can replace any of the top level/bottom level pieces with two shelf pieces, with the longer edge laid out adjacent to each other (this produces slightly more waste, but is still very efficient).

If you always remember to layout your pieces in this fashion, interchanging them as described above when needed, you will be sure to maximize the number of liners you can cut from one furniture pad.

Friday, May 15, 2015

What to Do for a Degloved Tail

Lilly with her degloved tail

(Warning: Graphic Image at Bottom of Post)

Monday night, when we took Lilly and her boys out to play, we noticed that Lilly had degloved the last 1 1/2" of her tail. Degloving occurs when the skin of the tail separates from the body, exposing the bone and tissue underneath. She may have gotten it caught somehow, or she may have injured it during a scuffle with her boys, or her tail may have gotten bit by one of the rats in the adjacent cage, despite the cages being 5" apart. The latter is the most likely, as our Hammie loves to nip at tails that find their way through bars (tails on rats he lives with are fine, though). I have moved the cages a little further apart, so hopefully all tails will be safe in the future.

Degloved tails are probably one of the most common injuries in rats. This is because the degloving mechanism is a part of a rat's natural defense against predators. Should a predator catch the rat by the tail, the skin can easily detach and separate from the tail, allowing the rat to escape and leaving the predator with a section of tail skin. However, this mechanism can also kick in when an accident occurs - another rat accidentally (or on purpose) nips a tail, the tail gets caught on something, a door pinches a tail as it closes, a tail gets stepped on, or someone ignorantly picks the rat up by a tail (yet another reason you should never pick up a rat by the tail).
This was not our first degloving. Weasel degloved the tip of his tail (about 1/2") several years ago on New Years Eve just before midnight while free ranging during a late night play session. Because it had happened before, we knew what to do.

If there is extensive skin loss, you should wrap the exposed area in a clean cloth to control bleeding and seek veterinary assistance immediately, as the rat could go into shock.

In most cases, the amount of skin loss will be minor. If it is just the tip of the tail that is affected, you can usually begin treatment at home and see your regular veterinarian at the next available appointment. Degloving is rarely a life threatening condition, since it evolved as a way to save a life, not take it. So if there is minimal skin loss, there is no need to panic. That doesn't mean it isn't extremely painful or that you don't need to treat it properly, but with proper care, your rattie will likely recover just fine.

The tail should be cleaned and antibiotic ointment can be used to try to prevent infection. Pain medication is helpful. For Weasel, we gave him some Children's ibuprofen. For Lilly, we had metacam on hand from her spay, so we used that instead (we used the higher 1 mg/kg dose because I had seen that dosage used in a case study in the Rat Guide). After the wound is cleaned, antibiotic ointment applied, and pain meds administered, the cage liners and litter should be changed, and the rat can be returned to the clean cage. It is usually safest to keep the injured rat in a hospital cage, separate from the other rats, so that the other rats don't accidentally hurt him/her, until you have the okay from the vet. For Lilly, we closed the ramp between the top and bottom levels so that Lilly could recover peacefully on the bottom while the boys wrestled on top.

An appointment with the vet should be made as soon as available (but an emergency visit isn't necessary unless extensive skin loss has occurred or the rat is not behaving in a healthy way). The vet will examine the wound and may prescribe antibiotics and/or pain medication as deemed necessary. The exposed bone will need to come off. Sometimes, it will fall off naturally and the vet will tell you to wait a week to see if that happens. If it does not fall off on its own accord or if the degloving is more extensive, a surgical amputation of the exposed bone may be required.

Lilly has seen the vet and has had the bone amputated and she is recovering fine. She is back with her boys and does not seem to be in further pain. Likewise, Weasel recovered easily from his degloving incident.

For more information about degloving, see the Degloving Injury article of the Rat Guide.
Degloved Tail

Wednesday, May 13, 2015

Rats in the News: Even More Evidence that Rats Experience Empathy

Article: Rats Forsake Chocolate to Save a Drowning Companion

Not that the rat community really needs convincing, but more evidence has surfaced that rats experience empathy. In this study, rats chose to save a "drowning" rat over receiving chocolate 50% to 80% of the time. I wonder if a delicious yogie treat would skewer those results (just kidding).

Friday, May 8, 2015

What Every Rat Owner Should Know About High White and Megacolon

The wedge blaze on Mystery is a clue that he was likely high white.
His brother, Weasel (photo below), had even more signs of high white.

I normally don't care much about superficial rat traits like color, markings, ear type, and fur type. I admit that I do like to have variety, as it makes it a lot easier to tell the rats apart from a distance, but aside from that convenience, the physical characteristics of a rat are not that important to me. I have taken a passing interest in what the different marking mutations are, the different colors, the different fur types, etc, and some of the genetics behind them. But it is just an academic interest. I am never looking for a specific color, marking, or trait when I take in new rats. I take in the rats that need homes when I have a home to offer.

I have researched one specific trait, however, much more than the others. Despite all that research, my understanding of it remains incomplete and flawed. That trait is high white.

What is high white? High white is a term used to describe the color patterns that result when cell migration is delayed and the pigment cells do not reach their destination, resulting in patterns of white (unpigmented) fur. That sounds great, but what does it really mean? During fetal development, neural cells, including pigment cells, originate along the neural crest (a strip along the spine). From there, they migrate to other parts of the body as the embryo develops. If, for some reason, that migration is delayed, those cells start on their journey but may not reach their destination. In the case of the pigment cells, it means the cells that were designed to add pigment to the fur don't reach their destination and that destination area is left unpigmented, or white. So normally, the pigment cells start at the top of the back and migrate all the way down the sides toward the belly. But if they start a little late, they might make it only partially down the sides. The more the delay, the higher the white areas that will creep up the sides. High white markings can also affect the head, resulting in irregular white spots or blazes. This delayed migration can also affect pigment to the eyes, and sometimes results in the odd-eye phenotype (one eye is a different color than the other).

Weasel was almost certainly a high-white rat. He had odd-eyes (one Ruby, one black)
a lightning blaze, and white patches that crept up the sides farther than normal.

Does this mean that all rats with white on their sides or with blazes or other irregular white spotting are high white? No. There are some genes that cause white markings such as hooded, masked, Berkshire, bareback, dalmation, etc. These traits are usually associated with the hooded locus and are not high white markings. More often than not, blazes in the US are associated with high white markings. But there are other genes that can cause blazes that are not derived genetically from high white. As far as I know, odd eye is always associated with high white - although I could be mistaken. I have never heard of any other causes for odd-eye.

Gandolf and Sam (facing forward) are split-capped, which is a high white marking.
Their brother, Max (facing away) is a hooded like their mother.

Unfortunately, it can be very difficult to tell if a rat is genetically high white just by looking at it. Things like odd-eye, white running up the sides further than is normal for the standard markings, and blazes are clues that there is a higher likelihood of being high white. However, without a pedigree, it can be hard to know for sure.

So now comes the real question: Why do we care if a rat is high white or not? The answer to that is simple. High white rats come with a much increased risk for megacolon. What is megacolon? Megacolon is a condition where the proper cells that allow an animal to defecate do not reach the colon. Thus, the rat cannot defecate and fecal matter collects in the colon. The condition is always fatal. It is a very painful condition for which euthanasia is usually the only option. Most rats that develop megacolon die shortly after weaning. This is called early-onset megacolon. However, some rats with megacolon have enough functionality to survive normally into early adulthood, but eventually succumb to the megacolon and die at an early age. This is late-onset megacolon. Late onset megacolon is much more rare than early onset.

In many cases, when a physical characteristic like color/markings is associated with a condition, it is because the gene for the marking and the gene for the condition both appear on the same chromosome and thus both tend to get passed on together. The closer together on the chromosome the two genes are, the more likely they will get passed on together. Because of genetic transposition, a portion of one chromosome can sometimes break off and switch places with a portion of another chromosome, allowing traits on the same chromosome to be separated in the right circumstances. The closer two genes are together, the more likely they are to stay together (the break would have to be in just the right spot to separate them). Thus, traits that often show up together are more likely to appear close together on the same chromosome. In selective breeding, much work can be put into trying to separate the two traits (hoping for just the right transposition to occur). It can be difficult, but it is possible.

Unfortunately, it is not possible in the case of megacolon to separate high white from megacolon in this manner. That is because the gene combination that produces high white is also the same combination that can produce megacolon. Basically, the process that delays the pigment cells from reaching their destination, also delays the neural cells that stimulate the colon from reaching their destination. It is in fact the same genes that make high white possible that also make megacolon possible. You cannot selectively separate the two conditions because they are made possible by the same set of genes.

That said, most high white rats do not actually develop megacolon. The delaying of cell migration that causes high white marking patterns also can delay the neural cells from reaching the colon, but it is also possible and even likely that those specific cells will reach the colon just fine. It is very unpredictable. When breeding, you can predict with some accuracy whether the offspring may be high white by knowing the parents pedigrees. However, you cannot predict what the exact pattern of markings will look like in those high white rats. There is a lot of variability in how the high white is expressed and that variability is controlled by many other genetic factors. In the same manner, we cannot predict whether or not the needed neural cells will reach the colon in a high white rat. A greater delay in cell migration may produce more severe high white patterns and also may imply a greater risk for megacolon, and thus there may be high white lines where the risk is extreme and some high white lines where the risk is less, but the ability to predict whether or not megacolon will occur in any given high white is very difficult. The best you can do is look at pedigrees for patterns in the line.

There have been some genes that have been determined to be involved with megacolon. There is the Spotting Lethal gene (dominant is normal, recessive linked to megacolon). There is also the White Spotting gene (dominant linked to megacolon, recessive is normal). More recently, there have also been studies done showing a connection between the SOX10 gene and megacolon. But part of the problem with these genes is that they have incomplete penetrance. This means that while you might need the right genes to be present to actually have megacolon, the mere presence of those genes does not mean megacolon will develop. It just means the potential for megacolon is there. The actual inheritance of megacolon is polygenetic and the right conditions need to be produced for megacolon to develop. At least this is my understanding.

What does this all mean to the average rat owner? Basically, megacolon is a very nasty condition that we want to avoid at all cost. Most (but not all) rats that develop megacolon are high white rats. Does that mean we should never adopt high white rats because they are likely to die of megacolon? Absolutely not. That is a completely false assumption. Most high white rats are perfectly healthy. The ones that develop megacolon usually die in the first weeks after weaning. If they survive past the risky period, they most likely do not have megacolon and they are far more likely to die of other rat health issues like respiratory problems and tumors. There is very little risk adopting a rat with odd eyes or blazes or high white markings once they are past the risky early weeks.

However, there is a much higher risk associated with breeding high white rats. If you are going to purchase rats from a breeder, you should try to acquaint yourself with the signs of high white. Most reputable breeders will not breed high white rats. A breeder who is selling rats with high risk markings is likely not reputable and should be avoided. However, it is possible that similar markings are being bred from safer traits, so ask to see pedigrees to verify where those traits are coming from if you believe the breeder to be reputable. Some breeders have worked with high whites and have pedigrees showing that megacolon has not appeared in their lines. It is possible that they have selected out the most risky gene combinations to produce reliable breeding under their controlled setting. However, there is no guarantee that megacolon will not eventually show up in those lines and there is also high risk breeding those offspring to outside lines - especially with unreliable pedigrees, so casual breeders should never work with high white rats - even when obtaining stock from a more reliable source with pedigreed rats. And if you are a pet owner with rats with high white markings, you should take extra precaution to ensure they are never bred (spay/neuter or don't keep mixed sexes in the same home).

If you are interested in high whites or megacolon, I recommend the following sources, from which I have learned a lot. I don't promise my understanding of the issue is perfect, so if you have concerns or interests, please just use this post as a jumping off point, but refer to the sources below for more reliable information:

For info on the condition of Megacolon:
The Rat Guide's article on Megacolon

For info on identifying High White markings (note that this article is no longer on the web and is only available through the Internet Archives Way Back Machine):
High-White and High-Risk

For info on the connection between high white and megacolon in embryo development:
Why Do Some Rats Have White Blazes and Megacolon

For info on some of the genes that are tied to megacolon:
Mutations in Rat Coat Color
Curiosity Rats: Genetics