External Parasites

veras physical exam 8-14External parasites are fairly easy to prevent. Keeping your rats’ cage and room immaculately clean and disinfecting regularly are key to avoiding parasites. Bear in mind that, despite maintaining a rigorous cleaning routine, external parasites may still be introduced by a new rat you’ve brought home or by commercial rodent bedding, litter or any other object that has come into contact with an infested rat.

Mites are the most frequent external parasite found on pet rats. Less common are lice, fleas and, very rarely, ticks. One of the main symptoms is itchiness. Keep in mind, however, that allergies to food, bedding and/or other environmental triggers can also cause itchiness. If your rats do have external parasites, eliminate them quickly as they can cause disease and/or internal parasites.


deans tail1

Scabs on a pet rat’s tail can be a sign of mites

If all of your rats are itchy and have scabs, they are likely to have mites. An exception may occur when you have a rat who is stressed, ill and/or elderly.  He or she may show symptoms of mites without the others being bothered at all. In this case, your elder rat may have a compromised immune system, making him or her more susceptible to mites.

Here are the various types of mites your rats may encounter:

Rat Fur Mites (Radfordia ensifera)

Fur mites are the most common type of mite found on pet rats. They are often normally present in small numbers without causing a problem. Mites as a cause of your pet rat’s itchiness are actually very difficult to diagnose. Your veterinarian may do a skin scraping or adhesive tape test and look at the samples under a microscope. However, these tests don’t always show mites even if they are present. Some vets choose not to do these tests and instead go straight to a treatment to rule-out whether or not mites are present. (See below for most common treatments used by rat-knowledgeable veterinarians.)

Ear Mange Mites (Notoedres muris)

Ear mange mites are much less common than fur mites. The symptoms of ear mange mites are crusty, scabby ears, nose, tail  and sometimes feet. These mites burrow into the skin and are microscopic in size and, (same as the fur mite,) live only on rats.

Meg initially only had her ears affected by mange mites (far left photo) and then it progressed to her nose (right two photos)

Initially, Meg’s her ears were affected by mange mites (far left photo). She later developed scabs on her nose (right two photos)

Tropical Rat Mites (Ornithonyssus bacoti)

The least common type of mites found on pet rats, the tropical rat mite can bite humans and other animals as well as rats. Once engorged with blood, they are visible to the human eye. Their color is generally dark red, brown or black. Tropical rat mites reside in cracks around the cage and only crawl onto a rat for a meal.

Treatment for Mites

The best treatment for mites is Revolution, a topical medication prescribed by your veterinarian. Even if skin scrapings and adhesive tape tests are negative, your vet may still prescribe Revolution. No harm is done by using this medication, even if it turns out your rat does not have mites. In fact, applying Revolution can help determine if mites actually are the cause of your rat’s itchiness.

Besides Revolution, Ivermectin and Mitaban are other medications that may be prescribed by your veterinarian depending on the type of mite and degree of infestation.

An alternative treatment for ear mange mites is the use of diatomaceous earth and vaseline. Meg, the young rat pictured above, was prescribed Ivermectin by her veterinarian to rid her of ear mange mites. When after several days Meg’s condition did not improve, her veterinarian recommended sprinkling her with diatomaceous earth (DTE) and applying vaseline to the scabby areas. DTE causes insects to dehydrate and the vaseline smothers them so they cannot breathe.

Licevera scratching

Lice are less common than mites. They can cause rats to scratch themselves as well as to lose fur. Rats don’t usually
develop scabs when they have lice. Lice are usually found on rats’ neck shoulders and back where it’s difficult for them to reach. They are visible without using a microscope, although a magnifying glass helps for viewing them. Tan or yellow in color, lice can sometimes have brown or red spots on them. The actual eggs are silvery in color.

Treatment for Lice

The most commonly used treatment for lice is oral Ivermectin. However, Revolution also works to rid rats of lice.


Fleas are even more uncommon than lice. Their presence usually signals there is a dog or cat in your household with fleas.


Ticks are very rarely found on pet rats. Similar to fleas, a rat would only have ticks if another pet in the household (such as a dog or cat) has them.

nora scratching revrTreatment for Ticks and Fleas

Make sure your non-rat pets are all on high quality flea (and, when indicated, tick) preventatives. Over-the-counter products are not always effective or safe. The best flea and tick preventatives are those recommended by your veterinarian. If your dogs and cats are flea and tick free, your rats will be too.


Any medications used must be prescribed by your veterinarian. Unless your veterinarian has seen your rat(s) within the last month or so, an exam is an important first step to getting diagnosed and for getting the proper medication prescribed. Finally, it is safest to purchase all medications from your veterinarian rather than online or from a pharmacy for humans.

In addition to the above treatments for external parasites ~


If it’s suspected that all of your rats are affected, you’ll want to completely empty their cage and clean and disinfect all of the contents as well as the cage itself. Discard anything inside the cage that’s wooden or cardboard. If there’s carpet in the room, it’s a good idea to have it cleaned professionally if you can. Professional carpet cleaners are usually relatively inexpensive and are able to do the cleaning in a very short amount of time.

It’s a good idea to clean and disinfect your cage and its contents at least once a week anyways. The Rat and Mouse Club of America has a very helpful guide to cleaning and disinfecting your pet rat’s cage on their website.

Sharp Toenails

Keeping your rat’s toenails trimmed will help prevent self-inflicted scratches and wounds. Broken skin created by scratching allows bacteria to enter. Once scabs form, they can become itchy themselves, resulting in a vicious cycle of more scratching, more broken skin, bacteria and scabs. Some rats need their toenails trimmed as much as one or two times per week.

Skin Infection

Skin lesion of unknown origin, may have been the result of excessive scratching and resulting infection

Skin lesion of unknown origin, may have been the result of excessive scratching and resulting infection

Infection occurs when the skin is damaged by scratching or bite wounds. The most common skin infection is caused by Staphylococcus bacteria. Rats with weakened immune systems are more likely to develop skin infections. Inflamed skin and sores most often occur on the head and neck. Abscesses can form and spread the infection under the skin. Eventually lumps or tumors can develop around the rat’s head. These types of infection are treated with antibiotics and often combined with steroids to help curb inflammation.

Tips for Preventing External Parasites

  • Take your rats in for regular well-rat exams at least once every six months
  • If you use prepackaged processed litter, freeze the bag’s contents before using
  • Freeze lab blocks and then thaw and feed—especially if you believe the contents of the bag may have been exposed to parasites
  • Keep your rats’ cage clean and disinfected on a regular basis
  • Quarantine all new rats. Three weeks is a good amount of time in which to prevent your existing rat(s) from being exposed to external parasites
  • After visiting with any rats outside your home, wash yourself well and to change clothes prior to handling your own rats
  • Keep your home free of wildlife, particularly wild mice and rats. If you find wild mice and rats in your home, locate food sources and secure them so they’re inaccessible to wild rodents. Outdoor bird feeders filled with seeds frequently attract wild rats. Use live-traps and relocate any rats and mice to areas away from homes.
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