Rats are prone to a number of health problems and most people agree that vets bills are the biggest expense associated with keeping rats. Although getting your rats from a reliable breeder can reduce the risk of health problems, it is by no means a guarantee and anyone thinking of getting rats should be prepared to fork out a lot of cash for vets bills, should it be needed. You may get lucky and never need to see a vet at any point in your rat's life but chances are, you will, particularly as the rat ages.

Below are the most common ailments rats suffer from. It should be noted that I am not a vet and my advice is based on experience and the knowledge I've gathered over the years.
If in doubt you should always see your vet. However, it is important to find a rat knowledgeable vet before you actually need to use one. A lot of vets know very little about rats, but are still willing to take your money, which is part of the reason you need to do your homework.
Do not assume for one second that by taking your rat to a vet, you will always see someone who knows more than you. 95% of the time, I know what's wrong with my rat and what medications he needs before my vet does and the only reason I need to take him at all is because you cannot get the medication without doing so. I feel I must mention this as on more than one occasion, my rats have been misdiagnosed by vets, or I've been told they couldn't do anything to help because the animal was a rat, yet I've still been charged full price for their 'services'. Fortunately, I have now settled on one particular vet who is very good with my rats, but it took many years to come by him.
The general public trust their vets to have a good amount of knowledge on their pets, but when it comes to rats, this often isn't so. If your rat is ill, by all means take him to a vet, but do research yourself online (assuming the ailment is not urgent. Any animal in serious distress needs to see a vet straight away) Don't be afraid to challenge your vet if you think he's wrong, it's not beyond the realms of possibility that he is, and a good vet will appreciate the knowledge you can share with him.

Respiratory Infections (Mycoplasma Pulmonis) Rats are very prone to respiratory infections. Mycoplasma Pulmonis (myco for short) is a bacteria that ALL rats have from birth.
It is passed from the mother to the babies in the birth canal. This is why all lab rats are born by caesarean section. SPF (specific pathogen free) lab rats are myco free because they are delivered in this way. It's important for lab rats to not have any health problems that may affect lab results. But all other rats, including wild ones, have Myco.

Myco lays dormant in the rats system until something causes it to flare up and become 'active'. Triggers include stress, bad breeding (resistance to active myco is partly inherited. Good breeders will only breed from rats that show good myco resistance) or bad husbandry. Myco can flare up and then settle down again and never cause another problem.
Or it may flare up and stay there for good.
Once active, Myco affects the lungs and if not treated, causes blisters on the lungs, pneumonia and eventually death. Myco cannot be cured but it can be controlled with antibiotics, and many rats that have active myco can live perfectly normal lives. However, Myco has a tendency to develop a resistance to antibiotics so your vet may need to try many different types over time.
The first signs that your rat is having a myco flare up are sneezing or any noises from the lungs. Rats should not make any noise when they breathe other than the natural moving of air. Any rattling, clicking or snuffling noises should be watched closely. Of course all rats sneeze and there's no need to start panicking if your rat starts sneezing more than usual. It doesn't always mean myco. Some rats have allergies or are ultra sensitive to their environment and it's worth considering if you have changed anything recently such as a new air freshener, carpet, a new litter in the cage or anything along those lines.
Some rats go through a sneezy period when they're first brought home; this is due to stress and often settles down within a few days.

If the sneezing continues for a long time, or is accompanied by any respiratory noises and any red discharge around the nose or eyes, it's a good idea to get your rat checked by a vet.
I recently heard someone describe their rat's myco noises as 'coffee percolator' noises which is pretty accurate! The red discharge is called porphyrin and is often mistaken for blood. It's not. It's a secretion that rats produce when ill or stressed. You'll notice that rats may produce it after a bath or vet visit or other stressful event.
Myco is the most common rat health problem closely followed by........

Tumours Female rats in particular seem to be much more prone to tumours than boys, though it's not unheard of in males too. My boy Seven had a mammary tumour. These are the most common types of tumour in rats since they have so much mammary tissue. Most turn out to be benign and can be removed; however, they can grow back.
Again, tumour resistance is something breeders breed for.

Some rats have one tumour, have it removed, then never have another problem, some have to keep having them removed for the rest of their life. Needless to say, this gets costly. Price of tumour removal varies depending on the size of the tumour, how its attached, and the vet practise doing the operation. Seven's tumour was the size of a grape when I had it removed and it cost me £56. Sometimes tumours appear in places where it isn't possible to operate on, or where an operation could prove more dangerous than the tumour itself. It's up to you and your vet to decide if the benefits outweigh the risks.
Seven was 2 years old when I decided to have his lump removed. This is considered old for a rat, and his lungs were not at their healthiest, but I realised that if he were not operated on, the lump would grow until it was bothering him or making him ill. Large tumours drain a lot of energy from the rat, and if they become too large, they can lose blood supply and the skin will die off, causing infection. At this point, he would have needed to be euthanized so it were better that he was at least given the chance and I agreed to have him operated on. As it was, he came out of the surgery fine.
But in some instances, owners let their rats be and live out the rest of their days until they get to the point where they seem to be suffering, when they will be euthanized. Another thing to note is that not all lumps are tumours. Some could be simple fatty lumps or even........

Abscesses These are fairly common. They usually occur as the result of a scuffle in which one rat bites another. Bucks have two glands on the belly, on either side of the penis, and these are prone to abcess in elderly rats. The skin here is particularly thin. As such, bucks will often get abscesses in this area.
Abscesses are fairly easy to treat and most people who have the stomach for it deal with them themselves. Of course if you have a skittish rat or you're squeamish then the vet is your best bet. It may be advisable to see the vet anyway, even if you do treat the abscess yourself, just to get some antibiotics as back up to stop the infection returning. Often, abscesses can be left to come to a head, and they will burst on their own. All you need do in this situation is keep the area clean. Make sure the rat has fresh bedding at all times and Keep an eye on the wound. You can bathe it in a salt water solution if your rat will allow. Abscesses can be quite painful for rats, so try not to touch the area too much. If it doesn't appear to get better, or actually gets worse, then take your rat to the vet.

Skin Problems Rats can get parasites such as ticks, fleas and lice but the most common is mites. They can pick these up from anywhere usually it's the bedding or the litter. If bags of litter have been sitting in a warehouse before being shipped to the pet shops, then it's likely wild rats or mice have come into contact with them, hence the mites.

The first sign of mites is excessive scratching and scabs.
Rats do scratch to clean themselves or when it's very hot. But if the scratching is especially excessive, its worth having your rat seen to. It's also worth noting that you can have a cage of 5 rats and only one might show signs of mites. This doesn't mean the others don't have them, it simply means their immune systems are healthy enough to keep it under control and they don't show any signs, so don't think that your rat cannot possibly have mites just because the other rats in the group aren't showing any signs.
Scabs commonly appear on the shoulders, front legs and around the eyes and whisker pads. Though not all scabs on the skin mean mites, scabs can also be caused by a bacterial skin infection or too much protein. A skin scraping often provides a false negative, so most vets will treat for mites anyway. Below you can see how Attila looked when he got a bacterial skin infection. This is very similar to what you will see if your rat has mites



There is only one method of treating mites which is truely successful in rats and this is Ivermec which you need to get from your vet. It can be either injected or applied topically to the skin, but all ivermec poses a small risk to your rats. I prefer it applied topically to the skin since I believe injections to up the risk even more.

Fits/seizures This is by no means a common problem in rats, but that's exactly why I'm writing a small piece on it. My rat, Jack, had seizures for most of his adult life and there was absolutely no advice anywhere online regarding rats and seizures. So I thought I'd share my experiences in the hope it would help other people having the same problem.
I first noticed Jack have a seizure when he was around a year old. I'd noticed periods of odd behaviour from him prior to that, such as seeming to go off into his own world or wandering in circles, but I didn't realise these were a form of seizure too until I began to research the condition in dogs.
A few times in the night I had woken to crashing in the cage and found Jack at the bottom of a ramp, or looking frightened, and always assumed he'd simply been fighting as he was the omega of the group. But I now know he was actually having seizures. Most of the time, he seemed to have them at night while I was asleep, though he did have a few while I was with him.

During a seizure, Jack's body would go rigid, he would paddle his legs, gnash his teeth and be unable to walk. This usually lasted less than 20 seconds, but he would then take anything up to an hour to get his bearings again. Immediately following a seizure, he would find it hard to walk, and often followed a circuit around his cage.
So what do you do about a rat that has seizures? The sad answer is there's not much you can do. I took Jack to the vet regarding his, and the vet pretty much told me she knew nothing about seizures in rats, only in dogs, and that she would prescribe him tranquillisers if I wanted, but I declined. It didn't seem right to be accepting medication from a vet who openly admitted she didn't know anything about rats. The vet told me she would go away and research the condition then get back to me. She never did.

Unless your rat is having seizures daily, and they are worsening, I would steer clear of drugs. Jack would only have one seizure every couple of moths or so, but he did go through a phase where he had many in one week. There are mixed opinions regarding how to handle your rat if you see him having a seizure. Some people insist they must be left alone, as any outside stimulus will only make it worse. Other people insist you should hold and comfort the animal. In general, I left Jack alone unless he was in a situation where he might get hurt, such as on a high level where he could fall. Most people with epilepsy tell you to leave them alone so I figured this was best for Jack too.

The only real dangers associated with this condition are the rat harming itself during a seizure or the seizures becoming so lengthy they run the risk of causing brain damage, in which case, medication should be used to control them. There is also a small risk of a rat biting it's own tongue while fitting, and with their teeth being so long their tongue can swell and block their airways, though chances of this are small, it's worth bearing in mind

I've never had a rat with this condition since Jack, and have only heard of a couple of others, so it seems to not be a common condition. If your rat does start to seizure, it's important to try and find a reason for it before anything else. Seizures could be a symptom of something serious. There was no outside reason for Jack's seizures, and nothing specific seemed to trigger them off. He was simply epileptic. But it's best to try and find a cause first before you assume this is the same for your rat.

It should be stressed that these are just the most common health problems of rats. If you are concerned about your rat then take it to the vet. Sadly, a lot of people seem to think that because rats are small and they don't cost much to buy, then they're not worth spending money on at the vet. Anyone with this attitude should not own rats. Be warned: they do become ill, and they can be costly.