By Kevin Wright, DVM, DABVP (reptile and amphibian) with excerpts from the Popular Critters Series magabook Hamsters with permission from its publisher, Lumina Media.
This continuation of the Hamster Health Center includes hamster illnesses and injuries beginning with the letters I through Z. The links in the list below take you to any of the hamster illnesses or injuries to learn all about hamster health. If you wish to go to Page 1 to scroll through hamster illnesses and injuries named A through H, click here.
If you don’t know a hamster illness or injury by name, check out our list of signs of illness in hamsters and possible causes, click here.
Scroll down or choose a hamster illness or injury here:
Congestive Heart Failure
Death and Euthanasia
Diabetes and Kidney Disease
Gastroenteritis (Diarrhea, Wet Tail, Bloating)
Hair Loss, Hair Thinning (alopecia)
Physical Trauma (Bites, Falls)
Reproductive Issues (Pyometra, Neutering, Polycystic Ovaries)
Respiratory Infections (Pneumonia, Colds, Sniffles)
Scent Gland Irregularities
Tumors (Lymphosarcoma, Hamster Polyomavirus And Others)
Itching (Pruritus) (Back to Top)
An itchy hamster will scratch and even damage its skin (self-trauma). This makes the irritation worse and an itch-scratch cycle may develop.
Demodex hamster mites are by far the most common cause of pruritus and self-trauma in hamsters. All hamsters carry a few mites in their skin, just as we all carry Demodex human mites. This has nothing to do with poor care or hygiene, and hamster mites will not infect people. Only when a hamster is old, ill, stressed or immunocompromised do the mites multiply and produce an infestation (called demodicosis) with signs including scratching, flaky or scabby skin and hair loss.
You cannot prevent hamsters from acquiring mites because they pick them up from their mothers during suckling. Infestation can occur later, however, when the hamster is ill, old or suffers any weakening of its immune system — only then will you notice a problem.
Your veterinarian can easily treat mites using prescribed oral, injectable or “spot-on” drugs. Often, elderly hamsters get a minor mite problem and this can be kept at bay with regular treatment. The underlying cause will not go away, however, and if treatment is discontinued the infestation may recur and spread or worsen. Ask your vet about retreating at home. Never use a treatment designed for dogs and cats on your hamster because it could kill your pet.
Occasionally, hamsters pick up other parasites such as sarcoptid mites, tropical rat mites, cat fleas or lice. These respond to the same treatment as Demodex, but ask your veterinarian to identify which parasite is involved, because other animals in your household may also need treatment.
Bacterial skin infections can also cause pruritus and skin problems. Prescription antibiotics from your vet clear up such ailments.
Allergies occasionally cause scratching and self-trauma, but identifying the cause can be tricky. Try changing bedding to unbleached, shredded toilet paper and watch for a reduction in scratching. Other causes may be dyes in hamster food, aerosols and cage-cleaning chemicals, so these should be investigated. Avoid cedar bedding, any type of aerosol spray and ask your veterinarian about safe cage disinfectants.
Malnutrition (Back to Top)
A hamster’s proper diet varies a bit by species. If a hamster is allowed to select out its favored treats and isn’t forced to eat a balanced diet, or if it isn’t offered a proper diet, it will develop nutritional deficiencies. Obesity is a common condition, and it results from hamsters that eat too many seeds and high carbohydrate treats and not enough grass, hays and other high-fiber foods. As a general rule, seeds are low in protein, vitamin A and vitamin E, and high in sugars and fats. Some hamsters, such as Roborovski hamsters, are more prone to protein deficiencies on a high-seed diet than other species, and show this with poor hair coat, poor fertility, poor growth and aggression. In all hamsters, vitamin A deficiency can cause dry skin and poor fertility and growth. A lack of vitamin E may lead to lameness, muscle weakness, heart disease, poor fertility and sudden death.
Follow the nutritional guidelines appropriate for your hamster’s species. Remember, hamsters are omnivores and need high-quality protein in their diet.
Malocclusion(Back to Top)
Hamster incisors (front teeth) grow continuously and sometimes overgrow and require trimming. The rate of growth varies by individual, age and angle of the teeth. Check the teeth daily for overgrowth. Trimming is usually only required every two weeks, if needed.
Ask your vet to explain the normal appearance of the incisors. Most pet owners have a veterinarian trim overgrown teeth.
Hamster teeth are normally curved, yellow to orange and don’t extend into the gums. A pair of incisors grow down from the upper jaw and a pair grow up from the lower jaw. The upper pair is longer. Hamsters have three molars and no premolars.
For general tooth health, avoid giving sugary snacks (hamsters are prone to tooth decay), ensure babies get enough calcium by using a hamster-specific food and keep checking the teeth! Offer dog biscuits or nuts in shells to wear down your hamster’s teeth if its normal food isn’t rough enough.
Mange, demodecosis (Back to Top)
A hamster may develop hair loss due to an infestation of mites belonging to the genus Demodex. These mites are normally found in the skin of healthy hamsters. If a hamster is stressed or debilitated from another illness, it may suddenly develop hair loss and crusty skin because the mites start to grow their population unchecked by the hamster’s immune system. The hair loss and crust is most often seen along the hind legs, but demodecosis may cause similar lesions anywhere on the body.
A veterinarian may diagnose demodecosis by scraping the skin, smearing the crust and hair onto a glass microscope slide, and examining it at high magnification (100 to 400x). Sometimes it may take multiple scrapings to find the cigar-shaped Demodex mites. As a general rule, if they are easy to find, they are likely contributing to the hair loss. If there are no mites found, or if only one or two are found, there may be something else wrong with your hamster.
Demodecosis responds well to daily or weekly treatments of oral ivermectin. Other medications have been used, such as selamectin and amitraz. Your veterinarian may suggest other diagnostic tests or treatments, because demodecosis usually is associated with other health problems.
Physical Trauma (Bites, Falls) (Back to Top)
Syrian hamsters will attack each other and should never be housed together as adults. Even the sociable dwarf hamsters can have quarrels. These may cause bite injuries, superficial or severe. The first bites are usually sustained on the belly as the less dominant hamster rolls over to display submission. Young hamsters usually nibble at ears in a fight. Youngsters also suffer nonspecific trauma to their ears. Bites are also commonly seen on the scrotums of competing males, which generally target the torso in a fight.
Separating the hamsters is the only way to prevent trauma from a fight. More space and lower light intensity can prevent aggression in some cases (dwarf hamster species only).
Minor bites that merely graze the skin and are not bleeding severely can be washed to prevent infection. Add a tablespoon of salt to a liter of water and bring this to a boil, then allow it to cool completely while covered with cling wrap. With a cotton ball, dab the salt water on the bites, trying not to wet the surrounding skin. This may sting, so be prepared in case your hamster jumps, nips or wriggles. Check the skin daily for signs of redness or swelling, and see your vet if these develop.
For more severe bites or scratches, see your veterinarian. Let common sense be your guide. If the wound continues to bleed, bleeds excessively, develops an inflammation or gets larger, it’s definitely time to visit the vet. He or she can also suggest suitable antiseptic preparations as alternatives to salt water. Do not use anything else on hamster skin without veterinary advice.
Fighting isn’t the only way hamsters can hurt themselves. They do not appear to understand the concept of height and will cheerfully walk off the edge of any surface. This probably relates to their limited sight (the distance from the bed to the floor is much greater than they think) and their flat natural habitat.
A long drop can fracture a hamster’s limb, an injury that requires veterinary care. Fractures can be dressed and splinted for optimum healing, but your hamster may repeatedly remove the dressing and splint. Do not despair, however, because most unsplinted fractures will heal completely, if slightly crooked. Open fractures (when the skin is broken) are more serious. After your veterinarian treats an open fracture, try to keep any dressing or splint on as long as possible and remove exercise wheels until your vet advises otherwise.
To prevent this type of injury, always handle hamsters close to a surface so they cannot fall far if you drop them. Do not let small children hold hamsters unattended and never leave a hamster alone when out of its cage or in a ball.
Wheel wounds and footpad sores should be rare if solid-surface wheels are provided. Should one of these injuries occur, treatment would depend on the type of wound. To reduce the risk to unweaned pups, remove the wheel from the cage until they are weaned.
Pinworms(Back to Top)
A hamster often has low levels of pinworms (Syphacia mesocriceti and possibly others) without showing outward signs of illness. However, research on laboratory mice documents changes in immune system function with pinworm infestation, so a finding of pinworms along with diarrhea, weight loss, unthriftiness or other illness merits treatment. Some hamsters with pinworm are intensely pruritic (itchy), particularly around the tail and lower back.
Pinworms may sometimes be detected through a direct or float fecal parasite examination. A more consistent method of detection uses clear tape placed on the fur and skin along the perineal region (i.e., around the anus). The clear tape is then placed on a glass microscope slide and examined under 100x or higher magnification. The ova of pinworms are unmistakable, sharply pointed football-shaped objects. Occasionally adult worms may be found in the feces or on the tape.
Ivermectin, fenbendazole or pyrantel palmoate may reduce pinworm levels, but it is often difficult to completely eliminate them due to their direct life cycle. A weekly or every other week treatment may be needed to clear a hamster of pinworms, and it may take one to three months to do so. It’s important to treat all of the hamsters in the home so that one doesn’t serve as a source of reinfection. In some cases, it may take higher doses than normal and longer treatment periods.
Since pinworm ovas are passed in the feces, hamsters may reinfect themselves as a result of their normal behavior of eating their own feces. It may also pass from hamster to hamster, and the eggs in the environment may reinfect a hamster that was already treated. You must spot clean the cage to remove feces daily and do a thorough cleaning every three to five days during treatment. Dump out all bedding, wash all cage furnishings in warm soapy water, then rinse well. Dilute chlorine bleach should be applied to all cage furnishings and allowed to sit for 15 to 30 minutes before being rinsed well with hot water. Don’t forget to disinfect your hamster’s holding cage and exercise balls or other outside-the-cage toys and play areas.
Reproductive Issues (Pyometra, Neutering, Polycystic Ovaries) (Back to Top)
All species of mature female hamsters usually come into estrus (heat) every four days and may then be hyperactive or irritable. Slight behavioral differences can be seen between the species at this time. Some Syrian females give off a musky, unmistakable odor during estrus and have a slight, milky vaginal discharge. Anecdotal evidence also indicates that it’s normal for some female Syrian hamsters to occasionally have a very small spot of blood in the genital area during estrus.
If you notice excessive yellow or unpleasant-smelling vaginal discharge, your hamster may have developed a pyometra (an accumulation of pus in the uterus caused by infection). A hamster with a pyometra will usually feel and look very ill, exhibiting one or more symptoms associated with a sick hamster. Veterinary treatment is essential. If your vet is not experienced at hamster surgery, ask for a referral. Pyometra is life-threatening but can be treated with prescribed antibiotics and ovariohysterectomy (surgery to remove the uterus and ovaries). Many vets routinely operate successfully on dwarf and Syrian hamsters.
Elective surgical neutering of male and female hamsters can be done. When not done by choice, these operations are usually performed to remove a pyometra or other reproductive tract problem.
Female hamsters occasionally get the hereditary condition called polycystic ovaries. This can make the abdomen bulge considerably and the hamster could double in weight. The ovaries can be completely removed by ovariohysterectomy.
Respiratory Infections (Pneumonia, Colds, Sniffles)(Back to Top)
Respiratory infections in hamsters can develop rapidly. Signs include watery eyes, rapid or noisy breathing and sniffles. These infections can be caused by bacteria, viruses, inhalation of food or water, hypothermia and getting wet.
Respiratory infections can be fatal and always require urgent veterinary attention. Treatment depends on the cause. Veterinarians usually give antibiotics in case the illness is bacterial and to prevent secondary bacterial colonization. Antibiotics may not work, however, if the main agent isn’t bacterial or if treatment begins too late.
To avoid respiratory infection, house your hamsters at a constant, normal room temperature and out of drafts or direct sunlight. Avoid excessive humidity and overcrowding. Use hanging drinking bottles, not water bowls, and never bathe your hamster in water, unless your vet specifically instructs you to do so.
Keep sick hamsters away from well hamsters, and if you have a cold try not to breathe or sneeze on your animals.
Scent Gland Irregularities(Back to Top)
All hamsters have scent glands. These glands communicate presence, territory and sexual status to other hamsters. Syrian’s have one on each flank, and these may be pigmented and slightly greasy. Dwarf hamsters have a single gland on the middle of their belly, near the navel. This is not usually pigmented, but is often very prominent and usually greasy, yellowed or even wet looking.
In all species, the male scent glands tend to be larger than those of the female. They may emit a musky scent that varies between individuals but should not be unpleasant, just unusual.
Hamsters rarely get infections or tumors of their scent glands. Each hamster’s glands look different. The daily health check will familiarize you with their normal appearance. If you notice any changes such as reddening, swelling, discharge, bleeding or crusting, consult your veterinarian.
Scent gland infections can be treated, but tumors are usually malignant (cancerous). Discuss treatment options and the prognosis with your vet.
Tapeworms(Back to Top)
There are two tapeworms that are associated with diarrhea and gastroenteritis in hamsters, Hymenolepsis nana and Hymenolepsis diminuata. Tapeworms may build up to such high levels that they may obstruct the intestine and cause constipation, bloating, poor growth, weight loss and death.
H. nana is a proven zoonotic, meaning that it can be transmitted to people. For this reason it is very important for your veterinarian to look for the parasite. Very fresh fecal samples are needed to detect tapeworms, and it may take multiple samples being evaluated over the course of a few days to find the tapeworm proglottids (egg cases) or ova (which may be free-floating if the proglottid has ruptured). You should notify your medical doctor of tapeworm exposure so you can assess if you are more at risk of contracting the tapeworm. Although proper hygiene like hand-washing is important when handling any small pet like a hamster, it is especially important to do so when a zoonotic disease is detected.
Praziquantel is an effective tapeworm treatment. All hamsters in the home should be treated at the same time to be sure there are no tapeworm carriers that could reinfect the home. A weekly treatment that is repeated for three to six weeks may be needed to clear a hamster of tapeworms. In some cases, it may take higher doses than normal and longer treatment periods. Because tapeworms can cause illness in people, once they have been diagnosed it is very important to do multiple fecal parasite examinations after treatment to ensure that they have been eliminated.
Tapeworm proglottids are passed in the feces, so hamsters may reinfect themselves as a result of their normal behavior of eating their own feces. It may also pass from hamster to hamster, and the eggs in the environment may reinfect a hamster that was already treated. You must spot clean the cage to remove feces daily and do a thorough cleaning every three to five days during treatment. Dump out all bedding, wash all cage furnishings in warm soapy water, then rinse well. Dilute chlorine bleach should be applied to all cage furnishings and allowed to sit for 15 to 30 minutes before being rinsed well with hot water. Don’t forget to disinfect your hamster’s holding cage and exercise balls or other outside-the-cage toys and play areas.
If the tapeworms are causing constipation or bloating, or if the tapeworm-infested hamster is dehydrated or passing mucus or blood with the diarrhea, the outlook is uncertain. Your hamster may need additional fluids by mouth or by injection beneath the skin, other antibiotics, pain relievers and assist-feeding. The more quickly a hamster is diagnosed and treated, the more likely it is to survive.
Tritrichomonas sp.(Back to Top)
Hamsters with diarrhea may be infected with a number of parasites, such as the one-celled protozoan Tritrichomonas. As with Giardia specie, this parasite may be found at low levels in the feces of seemingly healthy hamsters. At higher levels, it is often associated with gastroenteritis. We are not sure what makes some hamsters break with diarrhea while others are unaffected. Tritrichomonas may be detected from fresh feces observed through a direct fecal parasite examination under a microscope. These flagellated protozoa bounce around the fluid on the slide and are easily detected. As a general rule, if more than three are seen per high power field of a light microscope (about 400x), it is contributing to the diarrhea. If the feces are dry or have been room temperature for a while, the flagellated protozoa may encyst, making them much more difficult to identify and often requiring the techniques of a specialized lab. The best samples are collected straight from the hamster at the veterinarian’s office.
Tritrichomonas and most other flagellated protozoan parasites may be treated with albendazole or metronidazole, but all affected hamsters must be treated at the same time. Because the protozoan parasite is passed in the feces, hamsters may reinfect themselves as a result of their normal behavior of eating their own feces. It may also pass from hamster to hamster, and cysts in the environment may reinfect a hamster that was already treated. You must spot clean the cage to remove feces daily and do a thorough cleaning every three to five days during treatment. Dump out all bedding, wash all cage furnishings in warm soapy water, then rinse well. Dilute chlorine bleach should be applied to all cage furnishings and allowed to sit for 15 to 30 minutes before being rinsed well with hot water. Don’t forget to disinfect your hamster’s holding cage and exercise balls or other outside-the-cage toys and play areas.
If the diarrhea is causing dehydration, mucus or blood, the outlook is uncertain. Your hamster may need additional fluids by mouth or by injection beneath the skin, other antibiotics, pain relievers and assist-feeding. The more quickly a hamster is diagnosed and treated, the more likely it is to survive.
Tumors (Lymphosarcoma, Hamster Polyomavirus And Others)(Back to Top)
Older hamsters often develop tumors of some kind. The probability for tumors increases from birth. After one year, many hamsters have silent, internal tumors. These can be benign and totally harmless. Malignant (cancerous) tumors may grow, however, and cause pain, weight loss and death. The age when a tumor might become a health issue differs for each animal.
Have your veterinarian check any new lumps or bumps you discover during your daily health check. Many older hamsters have tumors called lymphomas on their internal organs and under the skin. These are common and probably will not affect your hamster. If a lymphoma is malignant (cancerous), it is called a lymphosarcoma and it may cause illness.
Tumors can’t be prevented. Treatment depends on a tumor’s size, site, biopsy result and differentiation/malignancy. The experience and preference of the veterinarian, and owner’s finances also affect treatment of a hamster with a tumor, which normally involves surgery.
During the health check, also notice your hamster’s weight. Cancer is a common cause of unexplained weight loss, so if you notice this happening, see your vet immediately.
Some Syrian hamsters develop benign skin tumors called trichoepitheliomas when infected by a virus known as hamster polyomavirus (HaPV). This is rare, but contagious to other Syrians. If your hamster develops wart-like lumps on its skin, ask your vet about HaPV, which can be diagnosed with a biopsy. No cure or treatments exist for HaPV.
Tyzzer’s Disease (Back to Top)
Clostridium piliforme is one of the many bacteria and other organisms that cause diarrhea in hamsters, often grouped under the term “wet tail.” This bacteria is anaerobic, meaning it lives without oxygen, and may increase to dangerous levels in the large intestine and cecum of a hamster that is stressed, particularly young hamsters that are being moved from one location to another. The bacterial spores contaminate the environment to infect other hamsters, quickly leading to a widespread outbreak.
It is not easy to confirm Tyzzer’s disease in a hamster with wet tail. A fecal sample may be sent to a lab to try and identify the bacteria, but the results may take several days. Many veterinarians start wet tail hamsters on the antibiotic metronidazole, which often helps eliminate Clostridium and certain parasites, such as flagellated protozoa. Other antibiotics may be needed, and fluids may need to be given orally or beneath the skin to treat dehydration. Some hamsters may need pain relieving medications and a liquid diet until they are improving. Other hamsters may be in severe pain that does not respond to treatment, develop a rectal prolapse, or develop other conditions where euthanasia needs to be considered. All hamsters that were exposed to the sick one should be closely watched and treated at the first sign of soft stool or a hunched posture suggesting abdominal pain.
Proper hygiene is needed to prevent spread of Tyzzer’s disease. Daily removal of soiled bedding coupled with hand-washing and washing all cage furniture and the cage in hot, soapy water is needed.
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