Behaviour + Care

Many places will recommend paper bedding over traditional wood beddings such as pine and aspen, fear mongering how they are dangerous due to the fact that they contain what is known as a “volatile organic compound” (VOC). While VOCs are harmful compounds, the kiln-drying process gets rid of these volatiles, rendering the bedding dry and safe. All farm and pet-grade softwood bedding will be kiln-dried in advance to remove moisture and potential pests.

Despite the advertisement of paper beddings being “dust-free,” paper bedding is also full of fine particles, which can inflame the respiratory system of rats. On top of this, paper lacks proper ammonia control. It has been found that paper bedding (CareFRESH Ultra) holds a significantly higher concentration of ammonia, accounting for nearly four times that of pine. Ammonia concentration in people is limited to 25ppm exposure per day under OSHA and UKHSE. In a rat cage, a rat will be much more closely exposed to ammonia, even at lower concentrations, than that of us in the same room due to the close contact with bedding and soiled hammocks.

Source: Evaluation of Cage Micro-Environment of Mice Housed on Various Types of Bedding Materials

Ammonia is the biggest contributor to respiratory irritation and subsequent inflammation in rats, as it destroys the cilia present within the lungs. Cilia are small, finger-like projections in the respiratory tract of all mammals, and work alongside mucous to push out dust, dirt, and harmful pathogens. When cilia are destroyed, pathogens will increase in number within the respiratory tract, resulting in severe respiratory illness in rats.
In modern laboratory facilities, softwood bedding is the preferred and recommended choice in rodent cages due to the reduced dust and excellent ammonia control it provides. This is used as the standard in both the United States and Europe, as outlined in the Guide for the Care and Use of Laboratory Animals.

Additionally, the paper bedding that is available for laboratory use is higher grade ​than that of the bedding available for ​pet grade, due to the requirements for continuity and safety in the lab. Paper bedding found in laboratories is significantly less dusty, and designed overall for use in different circumstances. In pet-grade bedding, many formulations also have unnecessary added dyes, perfumes, and baking soda added to mask the odour control it lacks.

If you are still uneasy about using wood bedding or you have allergies to softwoods, hemp or horse-grade cardboard are great alternatives.

For a more in-depth explanation complete with studies, please check out my writeup below:

Rats naturally have high protein levels in their urine. When rat urine comes in contact with human skin, the high concentration of protein can alert the immune system to a perceived “threat”, resulting in an overreaction to the urine. This typically creates small, raised bumps (hives). Rat saliva also contains these proteins, which can also lead to reactions. Hives from rat urine and saliva typically subsides over the course of an hour, and are more of an itchy nuisance than a serious problem.

In fact, allergies to rodent saliva and urine are well documented. Nearly one in three people who are most commonly in contact with rodents have been found to develop allergy symptoms related to the exposure of rat urine. Reducing allergen exposure, washing your hands and arms after handling rats, and taking over the counter allergy medication can help.

The Ohio State University College of Veterinary Medicine has published an exceptionally helpful guide on rodent and rabbit allergies, as well as living with them. The only time you should be seriously concerned about a rat allergy is if it produces severe anaphylaxis symptoms.

Breeding rats is a very expensive, time-intensive endeavour. It requires a well-trained individual under the guidance of a mentor and many years of preparation. Ethical breeders will have adequate facilities, access to quality veterinary care, and are capable of covering the financial costs of operations through other sources of income.Most breeders do not turn a profit for the rats they sell to the public. Most, in fact, operate on a net loss, as it is exceptionally expensive to run a rattery.

No properly bred rat should ever bite. While rats may nibble to groom, they should never draw blood. Keeping a biting rat poses serious risks to yourself and to their cagemates. Countless scientific studies spanning decades have shown that any sort of rat aggression is genetic in nature. It has been found that multiple specific genes, such as the Gltscr2, Lgi4, Zfp40, and Slc17a7 are contributors to the varying degrees of aggressiveness in rats. Specific regions of rodent DNA, known as quantitative trait loci, that correlate with tameness have also been identified. 

This means that biting is not learned or trained behaviour, but comes from the way their bodies produce chemicals in response to how their genes are expressed in stressful situations. Less aggressive, more tame rats have multiple differences in their endocrine and adrenal systems, including lower serotonin levels, reinforcing the biological basis of rodent aggression.

Some rat owners may be willing to put up with occasional nipping when scared - until that rat bites you in an artery or causes severe nerve damage. I have lost the feeling in two of my fingers as a result of rat bites over the years, and have nearly broken finger bones from being bit. Aggressive rats can also unexpectedly bite cagemates because the cagemate doesn't know how to avoid scaring it as well as you might. Attacks from other rats can become fatal quickly if intervention is not sought.

In addition, a rat that chronically bites is regularly stressed, afraid, and unhappy; this is not a good quality of life for the rat. Since aggression is on a genetic basis, it cannot be trained out. There are no reliable studies that prove that rats can be successfully trained out of aggressive behaviour. There are significant risks owning aggressive rats and it is important to understand before taking on a potentially aggressive rat.

The carrier method is often recommended for introductions of new rat(s) to a preexisting group, as it forces the rats to interact with one another. However, this is not as safe as it may seem. If a fight is to break out between rats, there needs to be ample space for them to separate from one another. Having space prevents the rats from backing one another into corners with no route of escape, leaving them no other choice but to defend themselves. This is exceptionally dangerous for not only the rats involved (which can be seriously injured through bites and scratches), but also yourself, as if a fight breaks out in a tiny carrier, the only way of separating them is for you to stick your hand in.

The safest way to conduct introductions is to place all of the rats in a neutral area such as a bathtub, and watch them closely for signs of aggression towards one another. A plastic ladle or spatula is recommended to have on hand so you can easily separate offenders from one another if a fight does break out, preventing injury to yourself and the other rats.

If there are no signs of aggression after about an hour of monitoring, placing them in a clean cage with no hides that allow a rat to be backed into a corner is your next step. Following this, if all is well, it is safe to add hides back to the cage as the rats settle in.

While rats enjoy climbing and moving around, by nature they are fossorial, meaning that they are ground-dwelling and enjoy digging and burrowing. In the wild, rats will climb trees and other structures, but return to their burrows for resting. Domestic rats have been shown to construct burrows indistinguishable from their wild counterparts. Providing rats with ample space to burrow as well as climb helps mimic natural behaviours and gives them options for rest and play.