By Lora Colver (edited by Bev Reeve)
Rats are prone to both internal and external parasites. All are easily treatable although you will need to take your rat to a vet if you think it may have internal parasites.
EXTERNAL PARASITES
Rats can become infested with mites, lice and fleas. Lice and fleas are wingless insects whilst mites are relatives of ticks and spiders. Any of them can carry internal parasites and other diseases that they can pass onto your rats, they also suck blood from your rat making him/her anaemic so it is important to rid your pet of these "visitors" quickly.
FLEAS: Your rats are most likely to become infested with fleas if you share your house with a dog or cat. If your house is infested with dog or cat fleas, some of them will be quite happy to take a vacation and go live on your rats for a while. The fleas are about 2mm long and are dark brown in colour. Their droppings look like black specks of dirt. You may also be able to see a few scabs on your rat where the fleas have bitten and caused an itch.
Even if you don't see the fleas themselves, you can do a simple test to see if your rat is infested by taking a tissue and dampening it. Put some of the specks of dirt onto the tissue. If they are flea droppings, red will bleed out onto the tissue, if nothing happens then they are simply specks of dirt.
LICE: Rat lice are a reddish tan colour and are most often found on the back, neck and shoulders. They vary in length from about half a millimeter to one and a half millimetres and are very thin and cigar-shaped. They are much easier to spot on lighter coloured rats, although the nits (eggs) can be easily seen attached to the hair shafts of dark coloured rats.
Lice will make your rats itch and scratch out their fur but rarely cause skin damage so you shouldn't see scabs. If scabs are present it's possible that your rat could have a combination of two or all three types of parasite.
Lice are species specific. The other animals in the house cannot get them nor can you, although you can pass them from one rat to another by stroking one infected rat and then touching a louse-free rat. Lice cannot survive on hairless rats.
MITES: There are three types of mite that like to take up residence in your rat's fur. In hotter climates, you may see the tropical rat mite. It looks more like a tick and is smaller than 1mm long. It lives not on the rat but in its cage, crawling on your rat only to suck its' blood. This type of mite will also bite humans and other animals.
The mange mite is so small it cannot be seen with the naked eye, being less than half a millimetre long, it lives in the skin of your rats' ears and sometimes also the nose, tail, feet and genitals. This mite burrows into your rat causing horny warts on the ears.
The fur mite lives on the skin or in the hair follicles. It sucks the blood and causes severe itching. Usually the first sign we see that mites are present are the scabs on the shoulders, neck and face. These are made not by the mite but by your rat. Neither the mange mite or the fur mite can live on humans or other animals.
So, how do we rid our pets of these unwelcome visitors?
Firstly, it doesn't matter if you can't actually identify what your rat has, since the three treatments listed below will work on all of them.
There are several products on the market, some better than others and some, if used incorrectly, that can prove very dangerous or even fatal for our rats.
The three most effective are:
FRONTLINE SPRAY: Available from your veterinary surgeon, you need the spray NOT the spot-on treatment.
Take a wad of cotton wool, or a cotton wool pad and apply one or two pumps of the Frontline Spray. Avoiding the face and genitals, making sure you are in a well ventilated area, rub the rat from top to bottom (including stomach, insides of legs, feet and tail), rub the fur the wrong way to make sure the soloution is applied to the skin rather than just the fur.
Repeat this procedure with each affected rat, once a week for three weeks.
The American version of Frontline is much stronger to the British version, which this document is referring to, and so the use of American Frontline is not recommended.
STRONGHOLD SPOT-ON: Available from your veterinary surgeon, you will need the spot-on tube for large dogs. This contains an artificial ivermectin called selemectin.
You need to make the smallest opening possible, so use a pin or needle to make a tiny hole.
Each affected rat will require one drop of Stronghold onto the back of one ear or the back of its neck. Keep the rat separate from others for a few moments so that it's cage mates can't lick the solution off.
Like the Frontline spray, this treatment needs to be repeated on a weekly basis for three weeks
IVOMEC/IVERMECTIN LIQUID: Again, this is available from your veterinary surgeon.
NEVER allow your vet to inject your rat with Ivermectin unless you are certain that s/he knows exactly what s/he is doing. An overdose of Ivermectin can cause neurological damage and can even be fatal. Similarly this is why the use of oral horse wormer paste shouldn't be used as overdose is very easy and can have devastating results on your pet.
The best way to use Ivermectin on rats when treating external parasites (Ivermectin is used for other ailments as well), is to use it in the same way as the Stronghold spot-on.
Ask your vet for a small amount of Ivermectin in an injection bottle and also ask for one or two 0.5ml insulin syringes, (don't worry, you're not going to stick the needle into your rat).
First of all, carefully snip the point from the needle of the insulin syringe. The needle is so thin that this can be done with normal scissors, but be careful the point doesn’t fly into your eye, make sure to put the point into the bin to prevent someone else finding it with a bare foot!
Draw up a small amount of the Ivermectin into the insulin syringe and then very slowly depress the plunger until the smallest drop of Ivermectin appears right at the tip of the needle. Then brush the needle against the back of your rats ear. This will ensure that the smallest amount of Ivermectin possible is dropped onto your rat.
Again, like the Stronghold, the idea is for your rat to ingest the Ivermectin so keep him/her away from his/her other cagemates for a few moments and don't stop him/her from grooming.
And also just like the other two treatments, this is repeated weekly for three weeks.
INTERNAL PARASITES
You cannot see worms or worm eggs as they are too small for the naked eye and you will need a veterinary surgeon to look at a sample of faeces (or urine) under the microscope. Treatment for worms should not be given to a rat unless a veterinary surgeon has had a positive sighting of them in a sample of faeces/urine. The treatment is usually a course of dog worming tablets at an appropriate dose (dependant on the rats weight) or Ivermectin.
WORMS: Rats can be prone to pinworms, bladder threadworms and tapeworms. An infestation by the pinworm normally causes no symptoms and is most likely to be seen in sick or overly-stressed rats. They can be transmitted by the rat eating wild insects such as cockroaches, fleas, mealworms and other grain bugs.
Tapeworms need to be passed through a secondary host, such as a flea or flour beetle (weevil), however, the dwarf tapeworm can be directly transmitted by eggs carried on cages, litter, water bottles, food, hands or through the air.
Tapeworms rarely cause health problems but a severe infestation can cause intestinal inflammation and weight loss. Rats with worms can also develop cysts on the liver.
The bladder threadworm is found on the wall of the bladder. Usually this worm causes no health problems unless it migrates to the walls of the lungs, it can also cause bladder stones. The worms’ eggs are passed in the urine rather than the faeces and can be passed from mother to offspring.
OTHER PARASITES: Internal parasites other than worms are not that common in pet rats. The symptom that a rat has internal parasites is usually diarrhoea but since this can also be an indication of poor diet or a reaction to an antibiotic, it's not an ideal method of diagnosing and a vet will need to examine your rat if you think s/he may have internal parasites. The vet can diagnose by examining a faecal sample under a microscope.
If your rats share your home with dogs or cats and are allowed to free roam, there is a danger of them picking up toxoplasmosis from eating dog or cat faeces so keep your rats well away from cat litter trays.
