Hamster Ailments - A resource of hamster related illness's and diseases

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Biology Like all myomorph rodents, hamsters have one pair of incisors and three pairs of molars in both upper and lower jaws. There are no canines, leaving a marked gap called the diastema, between the incisors and cheek teeth. The lips and cheeks bluge inwards through this gap separating “gnawing” and “chewing” sections of the mouth, and also making the back teeth very difficult to without special equipment. Hamster’s teeth are normally a yellow/orange colour.

Hamsters have open-rooted teeth, meaning that they grow continuously throughout life and must constantly be evenly worn down. Enamel covers the (outer) surface where as the inner (lingual) surface is coated by cement, which wears faster than the enamel so producing a sharp chisel-shaped edge to the tooth.


Teeth that are not worn down for some reason can overgrow and cause the hamster problems eating. This may because the hamster is not given enough opportunity to gnaw or if the teeth are maloccluded (do not line up as they should and so are worn unevenly). Malocclusion can be present from birth or may be due to trauma, such as a knock or fall, or persistent chewing of cage bars. Individuals born with this problem should never be bred from.

Signs that your hamster’s teeth are too long may include:

  • Anorexia/Decreased appetite
  • Weight loss
  • Swelling of the mouth or face
  • Excess salivation (wet around the mouth)

Teeth can easily be clipped by your vet. Use of nail clippers should be discouraged, as it may cause the teeth to shatter, causing further problems. Dental burrs are preferable. Individuals with maloccluded teeth may need their teeth clipped regularly, maybe even weekly.

A well-bred hamster fed on a normal hamster diet with opportunity to gnaw (wood chews, cardboard tubes etc) should not normally have this problem.

Dental Caries Dental caries can occur in hamsters as in any other animal, and can be associated with feeding diets high in carbohydrates (especially simple carbohydrates). For this reason sweet treats such as honeyed seed sticks/bars or hamster “chocolate” should be limited. Caries can go on to cause tooth rot abscesses.

Symptoms may include:

  • Excess salivation (wet around the mouth)
  • Swelling of the mouth or face
  • Anorexia

Treatment may be with antibiotics or extraction of the tooth under anaesthesia.

Foreign Bodies Occasionally pieces of food can become lodged between the teeth, leading to abscesses in the mouth and anorexia. The first obvious symptom of this may be excess salivation. The mouth should be examined carefully, and the offending object removed.


Biology The cheek pouches are large pockets in the wall of the mouth, used to transport food. When full they are easily visible as large swellings on either side of your hamster’s head.

Cheek Pouch Impaction This occurs when the hamster is unable to empty one or both of their pouches and they are persistently full. This may occur if sticky food is given, if there are dental problems, or occasionally simply if the hamster stuffs in too much food! The pouches can be gently everted under light anaesthesia, emptied and cleaned, and any abrasions or abscesses that have formed because of the problem treated at the same time. It is important however to rule out any underlying cause such as dental malocclusions, or the impaction may reoccur.

Cheek Pouch Eversion This is when one or both pouches becomes everted (ie inside out) and the hamster is unable to correct it themselves. This is more common in the dwarf species than in Syrians. The cheek pouch can gently be replaced using a small blunt object. If it is everted for too long it may become damaged or even necrotic, requiring surgery to remove dead tissue and replace the pouch.


Ocular discharge This may be a symptom of a concurrent respiratory infection, a foreign body in the eye, or conjunctivitis. Drafts or a build-up of ammonia in a dirty cage can also cause a discharge from the eyes.

An antibiotic or antibiotic + steroid eye ointment can be obtained from the vet. The eyes should be checked for foreign bodies, and the other causes above ruled out.

Glaucoma This is an increase in the pressure inside the eye and is rare, but most frequently reported in Campbell’s and Winter Whites. It presents as enlarged, bulging eyes. Lubricating eye drops can be used to prevent the eyes drying out, and surgical removal of the affected eye(s) can be considered in some cases. Hamsters with glaucoma can live a relatively unaffected life if given good support from their owner, but should not be bred from as it is thought to be an inherited condition.

Eye prolapse Prolapse or rupture of the eye can be caused by injury from trauma or fighting, or glaucoma. The eye will usually heal by itself without surgical intervention. Antibiotics should be given for 5-7 days to prevent complications.

Micropthalmia Some hamsters are born with small eyes or no eyes at all. This is the result of a recessive gene carried by some black-eyed white hamsters, dominant spots and all white-bellied hamsters. Breeding of these types should only be carried out by people who understand the genetic inheritance of this condition. Blindness can usually be coped with by a hamster with good support from it’s owner, but the condition is further complicated as it is also combined with lack of teeth, presenting further problems

Cataracts This presents as an opaque (cloudy) eye in an older hamster. It may be associated with diabetes. The hamster may suffer complete loss of sight but this can be coped with. Again, this may be an inherited condition so affected hamsters should not be bred from, however as it usually occurs in elderly hamsters it may be too late, so offspring should be checked regularly.


Ear mites Both dog and cat ear mites may affect hamsters, and there is a hamster ear mite as well. Symptoms would include crusting inside and around the ears and sometimes on the face and feet as well. Treatment is with ivermectin (oral or injection) from a vet.

Skin Problems

Biology Hamsters have two scent glands, also known on hip spots, one on each sid. They can sometimes appear as a dark discolouration of the skin and are often more noticeable in males. Dwarf hamsters also have a ventral scent gland.

Alopecia Alopecia (hair loss) is the second most common problem in hamsters after diarrhoea. There are a number of possible causes including mites, hyperadrenocorticism (Cushing’s disease - see Cushings Disease in Syrian Hamsters), fungal infections or old age.

  • Demodex mites – Demodex mites are found on normal healthy hamsters, but may cause problems in sick, stressed or elderly hamsters. Hair loss may be combined with scaly, flaky skin, usually on the hamster’s back. A vet can make a diagnosis by examination of skin scrapings under a microscope. Treatment consists of ivermectin (oral or injection) and bathing the affected area with a medicated shampoo, both available from the vet. Antibiotics may gave to be given if a secondary bacterial infection has occurred. Consideration should be given to the fact that this condition is indicative of an underlying problem.

  • Other mites – Hamster’s skin can also be infected with sarcoptes mites (usually affecting the face, causing itchiness as well as hair loss), or ear mites. These can be treated as above, but care should be taken not to infect other pets.

  • Hyperadrenocorticism see under “Endocrine diseases”

  • Fungal infections are a rare cause of hair loss. There may be patches of hair loss or it can be generalised, with flaky or greasy skin, and sometimes itchiness as well. Diagnosis can by made by a vet using microscopic examination of skin scrapings or culture of the organism. Treatment is with antifungal medication, medicated shampoo or dip and by thorough cleaning of the cage.

  • Elderly hamsters – hair loss can be seen in older hamsters and is sometimes associated with chronic renal (kidney) failure or neoplasms (cancer). However sometimes it is just a symptom of old age. It can also be caused by the hamster rubbing on an exercise wheel that is too small, or by abrasive bedding, or by diets low in protein or high in cereals. Non-specific alopecia can sometimes be helped by giving 1-2 drops of cod liver oil daily, by feeding more fruit and vegetables (though these should be introduced gradually).

Cuts and scrapes Hamsters can pick up cuts and scrapes from fighting with cage mates, or injury on objects in the cage. Hairless hamsters are particularly prone to skin injuries, and their cages should be adjusted accordingly. Sores can be bathed in warm water using cotton buds or cotton wool, and perhaps a suitable cream e.g. Dermisol applied.

Supersatinisation The dominant satin gene (Sa) produces a shiny, satin-like coat, but hamsters homozygous for this gene (ie. offspring from a satin x satin mating) have a very thin coat that is considered aesthetically unappealing. These hamsters may be slightly more prone to skin injuries but no other health risks should occur.

Abcesses Bite wounds from fighting with cage mates can become infected and develop into abcesses, presenting as sudden swelling full of pus, which may burst. Treatment is by cleaning the wound and antibiotics (oral and topical), although some abcesses may require repeated draining and cleaning. Allergic dermatitiss – see under “Allergies”

Respiratory System

Respiratory infections Hamsters are susceptible to many of the bugs that cause coughs and colds in humans, but can be affected much more severely, with infection leading to pneumonia and death. There are also several organisms found on healthy hamsters that may cause problems in stressed, sick or elderly hamsters.

Symptoms may include:

  • Dyspnoea (laboured breathing)
  • Sneezing
  • Ocular (eye) and/or nasal discharge
  • Head tilt
  • Lethargy
  • Ungroomed coat

Treatment is by supportive nursing, and antibiotics from the vet. Olbas or eucalyptus oil applied sparingly (2-3 drops) around the cage, or evaporated nearby in an oil burner, may help, as may 1 drop of Sudafed (a human decongestant, 6mg/ml pseudephedrine hydrochloride) twice a day – check with the vet before you administer this.

Cardiac Disease In older hamsters, dyspnoea (laboured breathing or shortness of breath) may be caused by cardiac disease. The hamster may also tire more easily, sometimes collapsing after exercise. The hamster should be housed in a cage where it cannot climb or exercise, and care taken to not feed high fat foods such as sunflower seeds. There is no treatment for cardiac disease in hamsters.

Allergic Rhinitis – see under “Allergies”

Gastrointestinal System

Biology The stomach of a hamster is divided into two distinct regions, the forestomach (pars cardiaca) and glandular stomach (pars pylorica). They have a long coiled small intestine approx 40cm long and a large, sacculated caeccum which is folded over on itself in a complex arrangement. Normal Syrian hamster faeces is almost black, very dry and about 10mm long by 3mm diameter, being proportionally smaller in dwarf species. Coprophagy (eating faeces) is normal in the hamster and allows them to ingest B vitamins produced by the microflora of the caecum.

Proliferative Ileitis – “Wet Tail” Also known as Transmisible Ileal Hyperplasia, almost all hamster owners will have heard of this disease. In some instances the term “wet tail” is incorrectly used to refer to all diarrhoea/enteritis in hamsters. It is almost exclusively a disease of Syrian hamsters and is more common in long-haired varieties. The bacterium Lawsonia intracellularis is currently considered a causative agent, but other organisms have been implicated. The disease is spread by a faecal-oral route between hamsters, and is associated with stresses such as weaning and changes in environment or diet, so is usually seen in young hamsters, very often soon after the move from pet shop to home.

Symptoms may include:

  • Watery diarrhoea
  • Soiling of the perianal region
  • Hunched position
  • Ungroomed coat
  • Lethargy
  • Anorexia

Death from dehydration may occur in 2-3 days, and more chronic cases may lead to rectal prolapse. Treatment is often unsuccessful and consists of supportive therapy and nursing.

  • The hamster should be kept warm and in a clean cage.
  • Dehydration may be corrected by giving intraperitoneal fluids (this would be done by a vet), or an oral rehydration solution (such as Lectade in the UK or Pedialite in the US) given by syringe or in place of the normal water.
  • Food should be withheld for the first 24 hours.
  • Antibiotics can also be given by a vet, usually by injection and followed by the owner using a syringe to give them by mouth.
  • Other possible treatments may include multivitamin injections or probiotic supplements, which may aid recovery.

Other causes of Diarrhoea

  • Dietary Change – This is typically bought on when a hamster is fed too much fresh food, especially food with high water content such as lettuce, celery or cucumber. Symptoms include loose droppings and soiling, but the hamster may initially remain bright and continue to eat. Treatment is to remove all food except for the dry mix, and perhaps offer burnt toast or cooled boiled rice. Green food should not be reintroduced until 3-4 days after diarrhoea has stopped. If the animal’s condition worsens then similar treatment to “Wet Tail” should be followed.
  • Antibiotic Associated – Caused by overgrowth of normal gut flora following administration of certain antibiotics (for this reason, the range of antibiotics that can be given to a hamster is restricted). Symptoms usually occur 4-10 days after antibiotic treatment, can be similar to “Wet Tail” and progress very rapidly. Treatment including fluid therapy and supportive care as for “Wet Tail” should be followed. Administration of probiotic supplements after antibiotic treatment can help prevent this condition.
  • Tyzzer’s Disease – Caused by the bacterium Clostridium piliforme, this affects the heart and liver as well as the intestines. Symptoms are a watery yellow diarrhoea, lethargy and dehydration, but in very acute cases the first symptom may be sudden death. Treatment is generally unsuccessful, but fluids, supportive therapy and antibiotics can be tried. This disease can be passed to other hamsters, rats, mice and gerbils.
  • Other infectious causes – Diarrhoea in hamsters can rarely be caused by agents such as Salmonella and E.Coli. Salmonellosis may present as diarrhoea or as sub-clinical disease (general loss of condition), but is a zoonosis, meaning it can affect humans too.

Constipation (Impaction) This can occur when access to water is denied, for example if the water bottle becomes blocked. Young pups are also prone as they may not be able to reach the water bottle. Lack of exercise and parasites may also be implicated.

Symptoms may include:

  • Swollen abdomen
  • Arched back
  • Protruding anus
  • Scant, very hard droppings or no droppings at all

Treatment can be by small doses of laxative, such as fig syrup, liquid paraffin or undiluted olive oil. 1-2 drops only should be given three times daily. Laxative foods include dandelion leaves or lettuce, which should be fed for a few days after the constipation has cleared. Care should be taken to not induce hypermotility of the gut which could cause further problems. Full access to water should be given.

Urinary System

Biology Normal hamster urine is thick and yellow with a pH 8, and should not be mistaken for pus.

Cystitis (bladder infection) Blood in the urine or straining to pee may indicate a bladder infection, which can be diagnosed by testing a urine sample. Antibiotics may be given.

Urolithiasis (bladder stones) There are normally small crystals present in hamster urine, which occasionally may form bladder stones. Signs might include bloody urine, increase in drinking, increase in peeing or not peeing at all. Large stones may be palpable, or the vet may use a urine sample, ultrasound or an x-ray to make the diagnosis. Surgery may have to be performed to remove the stone, although they are likely to recur.

Chronic Renal Failure Kidney failure is common in older hamsters, and may cause increased drinking and peeing and bloody urine. Restricting protein in the diet may help slow the progress of the disease.

Diabetes Diabetes is fairly common in older hamsters, and is also an inherited condition in some Campbell’s Russian and Chinese hamster strains. Signs include increased drinking and peeing and changes in behaviour (either lethargy or increased activity), and a diagnosis can be made by testing a urine sample for glucose. See the sticky thread “Is your hamster diabetic?” on the Campbell’s board of the Hamster Central forum for more information.

Female Reproductive System

Biology Hamsters reach sexual maturity at 3-6 weeks of age, although the ideal age for a first litter is 4-6 months old. Hamsters should not be bred for the first time after they are 7 months old. Females may continue to be fertile up to 20 months of age although some may stop as early as 11 months. Hamsters are polyoestrus and usually come into heat every 4 days, usually in the evening. Each heat can be followed by a small amount of white discharge, which is normal.

For information on gestation and litter sizes in the various species, see the “Breeding Hamsters” page.

Ovarian cysts These are fairly common in hamster which have not been bred from, and may cause a swollen abdomen and a bloody discharge. They may be detected by palpation or with an ultrasound scanner, and may be drained by paracentesis (using a needle) or removed by ovariohysterectomy.

Endometritis/Pyometra This is an infection of the uterus, which may cause a pus discharge, not to be confused with the normal white discharge at the end of each cycle (every 4 days). Ultrasound may show a swollen uterus, or cytology of the discharge may provide a diagnosis. Treatment is by ovariohysterectomy, antibiotics and supportive therapy.

Infertility There are various reasons that a female may fail to breed, including:

  • She is overweight
  • She may be on a low protein diet
  • She doesn’t receive enough daylight (14-18 hours of daylight and a temperature of 22-24°C is recommended)
  • She is inexperienced – try pairing with an experienced male
  • She is housed with another female who is dominant, and so she has suppressed her fertility due to social ranking.

Mastitis This is an infection of the mammary glands that can occur about 7-10days after birth. The teats will be warm, red and swollen and may have a pus or bloody discharge. It will be painful for the hamster to suckle her young and she may cannibalise them. Treatment is with antibiotics and supportive therapy.

Dystocia (Birth Complications) Gestation is normally 16 days in the Syrian hamster, and longer in the dwarf species (see breeding page). If the hamster fails to give birth when expected, veterinary treatment should be sought as she may require calcium and oxytocin injections to induce labour, or even a caesarean section.

Male Reproductive System

Biology Hamsters have relatively large testicles that may become larger and pinker when he gets excited. They are fertile at 3-6 weeks and may remain fertile throughout their life

Testicular tumours If the testicles become permanently enlarged, swollen or painful then a tumour may be suspected. Treatment is castration.

Infertility May be caused by:

  • Low protein diet or insufficient Vitamin E
  • Low environmental temperature
  • Overweight
  • Overuse (stud males should be used only once or twice weekly)

References & Further Reading

Books: “Diseases of Small Domestic Rodents” by V.C.G. Richardson “BSAVA Manual of Exotic Pets” edited by A.Meredith & S.Redrobe “Ferrets, Rabbits & Rodents: Clinical Medicine & Surgery” edited by K.Queensbury & J.Carpenter

Journal Articles: “The Biology, Care, and Diseases of the Syrian Hamster” by A.H.Battles, Continuing Education 7, 815-825

Websites: “Sputnik & Kosmo’s Glaucoma” by Mike Shmid, on the California Hamster Association’s website

Other sources: Exotic Anatomy notes – University of Bristol Anatomy department

Please take note that this ailments article was actually written by Emma Jarratt one of the Hamster Central Moderators. When she returns the article will hopefully be posted under her own user account.

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