INTRODUCTION

Rats, like all living creatures, can become ill no matter how well cared for they are; some diseases are more common than others because of their use in the medical field (cancer cure) or because of ignorance on the part of the owners, who do not provide them with the necessary care, do not realise it or unconsciously provoke these diseases (such as malocclusion and pododermatitis). 

Below, we will read about some of the most common diseases in these pets, which should always be treated by an exotic veterinarian. 

WHAT ARE THE MOST COMMON DISEASES IN DOMESTIC RATS?

SCABIES: Scabies can be of three different types but they all have one thing in common: they are caused by mites. 

• SARCOPTIC SCABIES: It is very contagious and usually affects the most sensitive areas of the skin, and it can take several weeks for symptoms to appear. 

• DEMODEX SCABIES: Uncommon in rats, it shows its symptoms in immunosuppressed animals. It is not contagious to humans. 

• OTODEX SCABIES: Affects the ears and is spread by direct contact. It can cause otitis and vestibular syndrome (tilted head). Prompt treatment is essential.

MICROPHTHALMIA: ‘Microphthalmia’ occurs when one or both eyes are smaller than they should be. There is a strong genetic factor here and, depending on its severity, it may or may not lead to blindness.

BENIGN CYSTS: In some cases cysts can arise after fights, blows or for no apparent reason; many of these cysts are sebaceous (fatty) or accumulations of dead/dirty skin. These cysts are of no concern and usually disappear with time, although some require emptying every few days. 

ALOPECIA: Alopecia (that which has nothing to do with the rat's coat type) can arise due to a variety of health problems, both physical and mental, and requires veterinary attention. Causes may include fungus, external parasites, stress, obsessions (hair pulling) or hormonal problems.

ECTOPARASITES: Rats can be affected by fleas, lice and ticks, which is quite uncommon in rats living indoors but can happen. In this case, we will go to the vet to get the necessary deworming (we will apply it to all the rats living in the cage) and we will thoroughly clean the cage and its accessories. 

RING TAIL: Ring tail is one of the diseases of the dermis (skin). It occurs most commonly in infants and young rats, environments with low humidity (>20%) or wire mesh floors. 

The tails of rats have very poor thermal regulation and all these factors mentioned above end up causing bloody lesions and necrosis of the tail, severe cases leading to amputation. Treatment depends on the severity of the case.

LEISHMANIA: Leishmania is a common disease in wild rats and uncommon in domestic rats. It is estimated that 33% of wild rats in Barcelona are carriers. The most frequent symptoms (if present) are skin lesions and it is still under study whether rats carrying this disease can be a danger to dogs.

RINGWORM: The skin lesions caused by ringworm (a fungus) are scaly and alopecic areas, although sometimes redness and itching can also be found. Ringworm can be contracted by direct contact with the fungus (either through contaminated objects or other affected animals), but it seems that stress and an incorrect diet can also cause it.

‘BAD GENETICS’ OR “GENETICS NOT CARED FOR”: The care of the genetic line is very important as not paying attention to this aspect can have important consequences in the short, medium or long term. Sometimes we find rats with physical or mental problems (especially physical ones) that irremediably reduce their quality of life, and this happens because they come from an incorrect or ‘abusive’ breeding line. What is an ‘abusive’ breeding line? Far from any kind of exploitation towards the mother (which does happen in pet breeding farms), an ‘abusive’ breeding line would be one that has an excessive inbreeding index; it is true that ‘linebreeding’ (parents x children x grandchildren) and ‘inbreeding’ (brother x sister) can be very beneficial if the breeding line is healthy and the breeder knows how to use it (as it will enhance all the good and all the bad) and knows when to open the line to ‘clean it up’. When this does not happen (for whatever reason) problems arise, like the malformation we found in the example above. It also happens in ‘non inbred’ lines but carriers of various conditions, so you have to be well informed and look very carefully at who you buy from.

MALOCLUSION: All living beings with jaws can suffer from ‘malocclusion’ or ‘prognathism’, which is a serious pathology in rats and other rodents or lagomorphs. This happens when the upper or lower jaw is longer (or shorter) than it should be, causing the incisors not to fit together (in rarer cases it can affect the molars), preventing them from wearing down properly and growing in an exaggerated manner. The cause of this condition is usually genetic, but it can also be due to inadequate nutrition, poor wear and tear (not being able to gnaw) or trauma. Untreated malocclusion (cutting of teeth or removal of teeth) can lead to worse injuries, such as anorexia, mutilation (digging in), dehydration, infection or death of the animal. These animals should never be bred.

LEPTOSPIROSIS: Leptospirosis is very, very rare in ‘domestic’ rats but common in ‘wild’ rats; it is a urine-borne bacterium that is acquired only by direct contact through contaminated food, water or objects. 

MYCOPLASMOSIS: ‘Mycoplasmosis’ is the most common respiratory disease in rats and most of them are carriers from birth, having acquired it from the mother through the placenta. Many of these carrier rats do not show symptoms and have a long life but, in the case of presenting them, they are complicated to eliminate, being serious and very contagious, and can cause cardiac problems. 

This bacterium can also be acquired from dusty litter (sawdust), dirt (urine vapours), allergies or by contact with infected animals.

PODODERMATITIS: ‘Pododermatitis’ is a skin condition found on the feet of many domestic rodents. It is a complex disease that occurs due to many factors (obesity, very hard floors, excess humidity, lack of hygiene, low mobility or too small cages), the skin becomes red, bleeds and oozes, which can lead to necrosis and, in the worst cases, death.

CONJUNCTIVITIS: ‘Conjunctivitis’ is a common eye infection and of little concern if treated in time, although its aggravation can be rapid and it is easily spread. The most likely cause of this infectious process is an inadequate substrate or a foul (dirty) environment that irritates the eyes, in the case of long-haired rats a hair can also cause the infection by getting into the eye, as well as other causes, such as entropion. If left untreated it can cause blindness.

CANCER: Rats are extremely prone to developing tumours of various types; this is because, for decades, these animals have been encouraged to develop tumours for further study in laboratories. Both males and females are at risk, with no higher rate in either sex, although breast cancers are more common in females than in males. These types of tumours can be reduced if the rat is sterilised, but the operations are very risky in this type of animal, so it is not recommended at all as a method of prevention. 

Early detection is very important to prevent them from growing too large or spreading.  Hopefully, recovery after surgery is quick and positive. 

OBESITY: Abuse of treats is one of the most common causes of obesity in ‘house’ rats, but lack of exercise is another. An obese rat is a sick rat, the fat will create ‘rolls’ that, with friction, can produce fungus or ulcers that end up infected, as well as respiratory, cardiac and reproductive problems, among others. 

BRAIN-BASCULAR ACCIDENTS: ‘Cerebrovascular accidents’ or ‘strokes’ occur when a blood clot plugs a blood vessel in the brain, causing a heart attack. Most rats that suffer one of these processes die immediately or within a few hours, while those that survive may end up with major injuries that can be life-threatening to a greater or lesser degree. Strokes can produce, if they live, motor or visual sequelae, among others. 

PYOMETRA: ‘Pyometra’ are commonly known as ‘uterine infections’, this happens when bacteria enter the reproductive tract during oestrus or mating, reproducing when the cervix closes. Hormonal problems, such as psychological pregnancies, can also be the cause of these dangerous infections. 

EPILEPSY: Epilepsy is a more common disease in rats than people think, due to experiments carried out on them to find causes and cures for these seizures. Some of the causes of epilepsy in rats can be: vascular (thrombi), congenital anomalies (hydrocephalus), inflammatory processes (meningitis), infections (viruses, bacteria...), toxic (poisoning), traumatic, tumours or degenerative processes.

ULCER: An ulcer is a crater-like lesion on the skin or mucous membrane. It forms when the top layers of skin or tissue have been removed. It can occur in the mouth, stomach and other parts of the body. Ulcers can be caused by inflammation, shock or infection. Some may be caused by cancer.

OTITIS: ‘Otitis’ is an inflammation (usually of the middle ear) caused by an infection. This type of infection is usually caused by fungus or humidity and, in addition to being very painful and annoying for the animal, its continuity over time without treatment can lead to ‘vestibular syndrome’ (tilted head) and deafness. In chronic cases that cannot be solved even with all possible means, one solution is to undergo surgery and remove the ear, subsequently closing the ear canal.  

VESTIBULAR SYNDROME: The ‘vestibular syndrome’ or ‘crooked head syndrome’ can occur in a great multitude of animals and, depending on the species, it is more frequent in one or another pathology, but one of the most common causes of this syndrome is advanced otitis. In this case we can observe the rat with its head slightly twisted (in the most severe cases it can leave it parallel to the ground). Animals suffering from ‘vestibular syndrome’ are very dizzy, walk in circles, fall down (walking or standing), their pupils move uncontrollably or they may vomit (if they have the capacity to do so). It is very important to go to the vet if we see these symptoms in our rat so that the cause can be found and appropriate treatment given.

Some animals, even if discharged, may never regain the correct posture. 

ABSCESES: ‘Abscesses’ are, simply put, ‘big’ pimples. They can be larger or smaller pockets of pus, and can arise from internal problems (malocclusion) or infections acquired through wounds. They usually open up on their own and heal well, others need to be drained in the operating theatre.

KIDNEY OR URINARY STONES: Kidney or urinary stones are not common in rats, but may occur in cases of poorly fed rats; an excess of calcium in the food or water causes the kidneys to work too hard to ‘work’ to cleanse the body of this excess calcium, which produces crystals. These stones (or crystals) are very painful and sometimes require medical intervention to pass.  Some symptoms of this are difficulty urinating, pain and bleeding.

BLINDNESS: Blindness is the inability to see due to disease (congenital or hereditary), malformation of the eye structure, illness or trauma. This pathology is much more common in rats with pink or red eyes, as well as in older rats. 

Blind rats can lead a good quality of life (as long as their environment is adapted to them) thanks to their whiskers, with which they orient themselves and mentally ‘draw’ their surroundings together with the rest of their senses.

REGULAR VISITS TO THE VET

As with all other animals, ‘fancy’ rats should have several veterinary check-ups throughout the year, so that we can make sure that they are in good health and, in the event of any problems, they can be dealt with as soon as possible.

Rats belong to what, in veterinary medicine, are known as ‘exotic animals’, so we should look for a vet who is a specialist in this type of animal. A ‘common’ vet (dogs and cats) does not usually have a sufficiently extensive knowledge to be able to treat or diagnose this type of pet. The best option is to choose a vet with a 24-hour emergency service, so that we can go to the vet in case of any emergency.

Veterinary check-ups should be carried out every six months. During these check-ups, special attention should be paid to the rat's respiratory system, as lung infections seem to be common in these animals. An untreated respiratory infection will kill your pet, as it will make it impossible for it to breathe properly, will cause fever, and the infection can spread to other nearby organs such as the heart, as well as end up in the blood. 

It is best to coincide these check-ups with the arrival of winter and the arrival of summer, so that we can prepare ourselves for the two most important seasons and the ones that usually cause the most pathologies. 

In these biannual check-ups we will not only check the respiratory system, but we will also carry out a coprological examination (study of the faeces) to detect internal parasites and, if positive, deworm with the most suitable product for that type of parasite. If our rat goes outside, it is advisable to carry out these tests much more frequently, as it is much easier for them to acquire parasites while walking in a public park than while living at home, in which case it is best to do them every three months. 

The teeth of our rats are also very important, it is one of the things that we must keep an eye on at home, as broken, chipped or mismatched teeth (malocclusion) can cause very serious problems in our rats, such as anorexia, ulcers, perforations, infections or death.

The nails are another thing that we have to check at home, if they grow too long they can cause several problems, not only that they can cause injuries by scratching us by accident, but also in the rat itself, as they can cause joint and bone problems by not stepping well, wounds (when the nails curve and dig in) and even back problems. The breeder of our ratites can teach us how and with what to count the nails of these adorable pets and, in case we are afraid to do it or do not feel confident, we can go to our vet to have it done by them at the vet's office.