The sores could be happening because of parasites, allergic reaction to bedding (I used carefresh bedding when I had rats and it worked really well), or their diet. Here's some stuff from a website that might be helpful:
Skin problems in rats are quite common, so you should inspect your rat's skin regularly. Some things you might find and what they indicate:
* Bugs moving about, or their eggs attached to the base of hairs - parasite infestation
* Scabs, cuts or other sores
* Excessive itching
* Hair loss
* Dandruff and dry skin - dry air in your rat's living area, over bathing, lack of EFAs in your rat's diet
* Rash, lesions, redness, offensive smell, skin infection, etc. - consult a vet for examination and treatment
* Orange oily discharge and/or dandruff - this is normal for hormonal males and is not a medical concern
Obviously if you see parasites, you've found the main cause of your rat's itching. But scabs, itching and hair loss alone are non-specific signs. If you don't find any particular reason for your rat's itching, then you need to work through the following steps to determine the cause.
2. Clip your rat's claws
If your rat has long, sharp claws, they can cause cuts and scratches to their skin during normal grooming. Likewise, if your rat is being barbered (over groomed) by a cagemate or fighting often, he may end up with scratches. In turn, the scratches will become inflamed and itchy, causing subsequent injury.
Clipping your rats claws regularly can prevent further injury. See Claw Clipping (previous article) for information and tips. You can apply antiseptic cream (preferably also containing anaesthetic) to any cuts to help with healing.
This may well solve your rat's itching problem, but if he continues to scratch then you need to move on to the next step. Even if it doesn't solve the problem, clipped claws will prevent further injury while you determine the underlying cause.
3. Treat for external parasites
Rats can get mites, lice and fleas, all of which can cause itching and scabs on the skin, particularly around the neck and shoulders. Information on identifying and treating these can be found here:
* What's bugging your rats and mice?
This is probably the most common reason for itching and scabs in rats. Don't rule out this possibility simply because:
(a) you can't see any bugs moving about - mites are tiny!
(b) you haven't introduced any new rats - parasites can arrive via contaminated bedding or food, wild rats having access to your rat's play area, or on your clothing after interaction with a friend's or pet shop's rats
(c) your other rats aren't scabby too - sometimes mites can overrun just one of your rats if his immune system is lowered.
It's often wise to treat for parasites before considering the other possible causes of itching and scabs. Determining dietary problems and allergies can take weeks of trial and error, while the possibility of parasites can be solved after one week of treatment.
No matter what the bugs are, ivermectin is usually prescribed. You can either take your rat to the vet for an injection (Ivomec), or better yet, dose him and all his cagemates orally with ivermectin yourself. You can get it from most pet or tack shops, sold as horse worming paste. [Equimec in Australia, Equimectrin in the U.S., active ingredient ivermectin - 18.7g/kg or 1.87%]. Adult rats (300-500g) get a small amount equivalent to a grain of uncooked rice. You should split the dose for younger rats, depending on their weight. Dose once a week, for at least 3 weeks. The paste isn't mixed well, and since you're giving such a small dose, it's safest to decant all the paste into a small container (like a film canister or baby food jar) and mix it well before taking the rat dose out.
I recommend Fido's Concentrate used along with ivermectin. Diluted to the strength used for birds, you can bathe your rat in it to kill the bugs and immediately ease itching while the ivermectin breaks the parasite life cycle. You can also make this up in a spray bottle for use in their cage and areas your rats are permitted in your home (carpet, furniture, etc), and add some when washing your rat's bedding. If Fido's is not available in your area, choose a lice spray containing pyrethrin (with no more than 0.15% pyrethrin)... one sold for birds is often a suitable concentration for rats.
Be sure to continue the complete 3 week ivermectin treatment as you still have to protect the rats from hatching eggs. You should strip down their cage and give it and any toys, hammocks, areas they play in, etc. a thorough disinfecting several times during the dosing. Also consider the possible sources of the bugs, like infested bedding and food, wild rat access to your pet's area, new rats introduced, cross contamination from your clothes, friends rats, pet shop, etc.
If your rat continues to scratch after one week, then the itching and scabs are probably not the result of parasites, so you should continue to the next step.
4. Consider your rat's diet
A diet too high in protein and fat can cause itching and scabs, in particular around the chin and face. Cut back on high fat and protein foods (like sunflower seeds, nuts, dairy products, meat scraps, etc.). Feed a balanced rat diet, like a rodent block and fresh vegetables and fruit. A vitamin supplement may also help. Information on a healthy rat diet here:
* Rat Health Food
* Rat Nutrition
* Food glorious food
A diet deficient in the essential fatty acids can also cause scabs (often along with dry skin and dandruff). EFAs are found in oily fish, seeds like flax and sunflower, and nuts (walnuts and peanuts in particular). They can also be obtained by supplement.
Rats, like humans, can have food allergies. Some problem foods include dairy products, corn and soy proteins. You will need to use trial and error to determine which, if any, foods are causing the problem. Remove one food each week, recording your rat's diet and skin response in a diary. Food allergies are not common in rats, and determining the problem food can take a long time to figure out, so consider all the other possible causes of itching first.
5. Consider your rat's living environment
Although uncommon, rats can have allergic reactions (like contact dermatitis) to products used in their cage or living room. It would be unusual for your rat to suddenly start to react to the bedding he's been on for awhile, but if you have recently changed your brand of bedding, this may be the cause of his itching. If so, changing back to the previous bedding, or using fabric strips and paper towels for awhile, would be a good idea to see if this is the cause.
Likewise, consider any other new products you may be using in your rat's area... cage cleaning products, washing liquid, fabric softener, deodorant, even your own perfume, scented candles, etc. As with food allergies, remove one product each week and record your rat's response in a diary.
Rat skin can become dry and flaky, and subsequently itchy, if they are kept constantly in dry conditions such as air conditioning and central heating. If this becomes a problem you can provide a humidifier, keep a water spray bottle on hand to dampen the air and/or your rat, or bring your rats into the bathroom with you when you shower.
6. Still itching?
If your rat doesn't respond to any of these treatments, you may be dealing with a skin infection (such as a bacterial infection, ringworm or other fungal infection, excema, etc.). These are usually identified by redness, lesions or a rash and should be examined
(usually by skin scraping and microscopic examination) and treated by a qualified vet.