Key Points About Rats
Here is a brief summary of the information we have found to be most helpful for Animal Care Professionals. More complete information on health issues, including drug dosages, can be found in the booklet Rat Health Care by Debbie "The Rat Lady" Ducommun. More complete information on rat care and behavior can be found in the book Rats, and The
Complete Guide to Rat Training, also by Debbie Ducommun. For more description of these publications go to www.ratfanclub.org/books.html.
| Average life span
|| 2 to 3 years
| Maximum life span
|| 7 years 1 month (Guiness Book of Records)
| Estrus cycle
|| Every 4-5 days, and immediately after giving birth
| Gestation period
|| 21 to 23 days, 28 days for a post partum pregnancy
| Average litter size
| Eyes open
|| 2 weeks
| Weaning age
|| 4-5 weeks
| Age at puberty
|| 5-6 weeks
| Physical maturity
|| 8 months
Domestic rats are true domesticated animals and are born
tame, but they still need to be socialized to bond to humans. Baby rats need to handled as much as possible
beginning at birth and especially between 2 and 4 weeks of age to make sure
they will be friendly and calm. It is a
myth that handling the babies will cause the mother to kill them.
Rats who were not properly socialized as babies will often
exhibit fear toward humans. But even
many of these rats can be rehabilitated using a method called Trust
Training. This technique uses soft food
on a spoon as both a lure and reward for desired behavior. For more info on this technique go to www.ratfanclub.org/trust.html
There are a few rat behaviors that are sometimes mistaken
for health problems. One of these is
when a rat stares into space, swaying or weaving his head back and forth. This behavior is most common in pink-eyed
rats and means the rat has poor eyesight. Moving their head back and forth helps their depth perception through a
phenomenon called parallax. As they sway
back and forth, closer objects seem to move more than objects farther away.
A female rat in heat can become jumpy, especially when
touched on the back. When touched, she
may also arch her back and vibrate her ears! Female rats in heat can be quite determined and inventive in reaching a
male rat, for instance, leaping huge distances or squirming through cage bars,
and must be securely confined.
About 5% of male rats show abnormal aggression. The only
solution to this behavior problem is to have the male neutered. It can take up to 8 weeks (probably because
the brain must reorganize), but neutering will eventually be 100% effective in
eliminating the aggressive behavior toward humans and 90% effective for
aggression toward other rats. Neutering
will also reduce urine-marking behavior, as well as the normal secondary sexual
characteristics such as rougher coat and heavy oil production from the skin on
the back, although it does not have any significant health benefits for male rats.
Rats are highly social animals and do best with a cagemate. A single rat can become insecure and nervous. Studies have also shown that single rats tend to get sick more than rats in groups. We recommend that rats be kept in same-sex or altered pairs or groups. As long as the rats are properly socialized, they will still enjoy interacting with their owner. A single rat must have several hours of human interaction every day. It's best if rats can come out of their cages to play for at least 30-60 minutes every day.
Rats need a cage large enough to provide room for toys and exercise. Minimum should be 14" X 12" X 24" but bigger is better. Rats also need a place to hide and sleep such as a box or a hammock. Toys are not optional, they are required for the rats' health and well-being. They enjoy climbing toys such as ladders, branches, concrete blocks, and ropes as well as tubes and boxes. A large plastic exercise wheel is highly recommended as most rats really enjoy running on a wheel. We recommend Wodent Wheels at www.transoniq.com
Pine and cedar shavings should not be used in rat cages because they contain acids that damage the respiratory tract. This is especially dangerous since the most common health problems in rats are respiratory infections. Pine and cedar shavings also contain toxic phenols that are absorbed into the blood. Studies show that long term exposure can cause an enlarged liver, altered immune response and decreased fertility and litter size. (If you would like a copy of these studies please let us know.) You will find a list of safe alternative beddings at www.ratfanclub.org/litters.html
The best commercial food for rats are rat blocks or nuggets. These food pellets supply a complete and balanced diet. A fortified grain mix can also be used, but many rats will pick out and eat only their favorite bits leading to an imbalanced diet and wasted food. Their diet should also include a variety of fresh fruits and vegetables.
Baby rats should be weaned no earlier than 4 weeks, and waiting until 5 weeks is better. At 5 weeks the males and females must be separated because some rats become sexually mature at this age and pregnancies can result.
It is a myth that rats need hard things to chew on to keep their teeth from over-growing. Their incisors are designed to rub against each other to keep them the proper length and sharpness. Only when disease affects the teeth, or they are out of alignment, will they overgrow.
Common Health Problems
The most common health problem in rats is bacterial
respiratory infections, which in older rats are often accompanied by congestive
heart failure. Also common are tumors, abscesses, spinal nerve root
degeneration causing paraplegia in older rats, and lice or mites. Rats have a brownish-red pigment in their
tears called porphyrin and when a lot of this gets caked around their eyes or nose or on their ears or fur it is a common non-specific sign that can be caused by respiratory
disease, stress, or eye irritation.
See below for more details on the most common problems. More
info is available at www.ratfanclub.org
and in the booklet Rat Health Care, which is described at www.ratfanclub.org/books.html
underlying cause of respiratory disease in rats is infection with the bacteria Mycoplasma
pulmonis. This disease is extremely
contagious and is transmitted from mother to offspring shortly after
birth. Pretty much all pet rats have it,
whether or not they have symptoms, and it is incurable, although aggressive
antibiotic treatment can keep it under control. Mycoplasmosis makes the rats more susceptible to frequent secondary
bacterial infections as well.
symptoms in young rats are almost always caused by secondary infections, which are
best treated with amoxicillin. Secondary infections can quickly become acute
and deadly so should be treated promptly.
treating rats, if there is no improvement within the first 2-3 days another
antibiotic should be tried. When a treatment is effective, antibiotics for a
secondary infection should be continued for 2-3 weeks, to prevent relapse. When enrofloxacin or doxycycline is used to
treat mycoplasma, treatment should continue for at least 6 weeks and these
antibiotics can be used long-term without any danger. (One of my vet’s patients was a rat who lived
4 years, and was on Baytril the last 2 years of her life.)
Congestive heart failure is common in older
rats, but fortunately, can usually be successfully controlled with drugs.
Rats usually heal quickly due to their fast metabolism,
and often veterinary treatment is not needed for injuries. Lacerations -
even if all the way through the skinl - up to 1 ½" long do not need
suturing. Even broken legs usually heal well on their own. Degloving of
the tail is a natural response and the damaged tail normally does not
need to be amputated. The exposed tissue will dry up and fall off on its
own in a few weeks. Treatment is needed only if infection or
Severe swelling of a foot due to injury does need
treatment as it will tend to get worse due to compression of the veins.
Ibuprofen can also be given at 60 mg/lb twice a day.
half of all unspayed female rats will develop benign mammary tumors, and it is
common for a rat to get multiple tumors. Although these tumors are easily removed by minor surgery, it is
expensive, so it is best to get female rats spayed when young. Spaying
significantly reduces the chance of both mammary and pituitary tumors. If a rat
does get mammary cancer, surgery won’t help, but treatment with tamoxifen can
be highly successful. Mammary tumors are uncommon in male rats, but male rats
often get benign fibroma tumors on their side. The only treatment for these is surgery.
tumors, which grow under the brain, occur in about 16% of unspayed female rats
and in about 4% of male rats. The main symptom is poor coordination and eventually
the rat will have trouble eating. Treatment with cabergoline can be highly
effective for up to 8 months.
Abscesses are a common occurrence in rats and most abscesses on the body will open, drain and heal up on their own. Males are particularly prone to abscesses in the groin. Abscesses on the face can be much more serious. An abscess on the face or under the ear that does not quickly heal after being drained is most likely caused by a cancer.
The two most common
external parasites in rats are lice (Polyplax spinulosa) and fur mites
(Radfordia ensifera). The species specific lice are visible and often do not
cause symptoms. They can be treated with oral ivermectin at 100-200 mcg/lb once
a week for 3-6 weeks or by one dose of selamectin at 6 mg/lb or one dose of
moxidectin at 1 mg/lb.
Fur mites are also
species specific, are microscopic and live in the hair follicles. Skin
scrapings can often be negative even when mites are present. Rats can harbor
these mites without symptoms, but when symptoms occur they are scabs on the
shoulders, neck, throat or chin. In the United States ivermectin used to be effective
for fur mites but they are now immune to it. The only effective treatment for
rat fur mites now is selemectin or moxidectin at the same dose for lice.
The best nutritional supplement for sick rats is
powdered soy baby formula, which can be mixed as thick or thin as
needed. Rats will also often take foul-tasting medications in it. It is
best to try to get rats to take their medications willingly by mixing
them into a tasty liquid or food. However, medications can be forced by
putting only 0.1 ml in the back of the mouth at a time.
The best place to give injections to a rat is in the
loose belly skin in front of the hind leg. The skin at the nape is ten
times thicker. All injections can be given subcutaneously.
Rat Health Insurance
The Veterinary Pet Insurance company offers major medical policies for almost any type of animal. This policy can make more extensive health care, such as mammary tumor removals and diagnosis and treatment of heart failure, affordable. For more info go to www.petinsurance.com or call 800-USA-PETS
For More Information
For more information see www.ratfanclub.org or Debbie's booklet, Rat Health Care described at www.ratfanclub.org/books.html.