Causes of Sudden Death in Hamsters
Hamsters are some of the most common small pets in many countries as well as a common "starter" pet for younger children due to their small size, relatively easy care, and wide availability.
Sometimes, even the very short lifespan of hamsters can be appealing for parents who want to get a pet for their child but don’t want to get stuck with it when their child moves out. Unfortunately, many hamsters will go through what is often referred to as their hamster dying unexpectedly or for “no reason.” In some cases, two hamsters will even die close to each other or at the same time. It should be noted that this is a very common occurrence and is often not the fault of the owner.
Signs of Illness
While it can sometimes seem like hamsters pass away with no warning, many animals are notorious for hiding their illness until they are too sick to do so. This is usually when they are moments away from death. This is why it is essential to take seriously any change in your pet’s behavior, as the signs of illness are often extremely subtle. It could be a potential red flag if your hamster exhibits any of the following symptoms :
- Lethargy. If your hamster seems less active, particularly if it is still in its prime, this can be a sign of advanced illness.
- Increased sleeping times. This can be expected of older hamsters but can also indicate illness.
- Their coat is unkempt.
- Anorexia or change in appetite.
- Any change in defecation.
- Any change in breathing.
- Increased drinking or urination.
- Weight loss. It can be incredibly beneficial to weigh your older hamster once a week to monitor any changes in weight.
- Excessive grooming.
1. Old Age
Of course, given that hamsters have an average lifespan of 18 months to a year with a maximum of 3 years , most hamsters are not expected to live long. If you have adopted your hamster at an adult age and have no information on how old it actually is, your hamster could have easily been near the completion of its natural lifespan.
Age is not a disease, however. It still is a good idea, if you have the opportunity, to have a necropsy done of your pet to try to find out for sure, as old age can sometimes become a red herring. Please also note that if your hamster has been kept in colder conditions, that can induce your pet to hibernate and appear dead.
A necropsy can often bring peace of mind to the pet owner if it is discovered that the cause of death was not preventable (this can also occur if your hamster was not elderly). Advanced age in animals can also exacerbate some undetected preexisting condition. Veterinary medicine is limited compared to human medicine, and there are even less options for very small "exotic" pets, so some conditions that are treatable in dogs and cats may not be feasible for hamsters.
Stress is not a disease but a condition that can dramatically affect your hamster’s lifespan by weakening their immune systems, leading to illness. The bacterium Clostridium piliforme can be opportunistic in stressed, immunocompsomised hamsters . Stress can also exacerbate preexisting conditions such as heart disease . It is commonly suggested that hamsters that’ve died unexpectedly died from a heart attack or stroke, which can be induced from acute or chronic stress . This can also be a normal age-related death.
3. Heart Disease
- Congestive heart failure in hamsters is a likely cause of death for hamsters that die suddenly. This occurs when older hamsters or hamsters with a genetic predisposition have weakened heart muscles that cannot efficiently pump blood. Respiratory distress, erratic movements, edema (fluid retention in the abdomen) and blueish color to the skin are possible symptoms .
- Atrial thrombosis is extremely common in older hamsters with occurrences of up to 70%. Thrombosis commonly occurs secondary to heart failure. Some symptoms include cyanosis (feet are a blue color), hyperpnea (rapid breathing), and death after a week of these signs .
- Some diseases, like polymyopathy, can be hereditary . Transmitted by a recessive gene, the disease involves the heart and the weakening of the muscles, eventually leading to early death due to cardiac failure in some hamsters .
- One study observing the changes of "healthy" and cardiomyopathic (CM) hamsters found that CM hamsters had shorter lifespans and underwent damaging pathological changes to their heart earlier. Some of these hamsters died as early as 11-13 months naturally . Therefore it is possible for heart failure to occur well below a hamster's expected lifespan.
4. Wet Tail
"Wet tail" is a common term used to describe diarrhea in hamsters, and it can also be referred to as proliferative ileitis, regional enteritis, terminal ileitis, regional enteritis, enzootic intestinal adenocarcinoma, atypical ileal hyperplasia, and hamster enteritis in golden hamsters . It is one of the most common spontaneous diseases of hamsters , and is often distinguished as an infection by the bacterium Lawsonia intracellularis in young hamsters (3-10 weeks old) .
Diarrhea in adult hamsters can be associated with the bacteria Clostridium difficile, Escherichia coli, Proteus morganii or Clostridium piliforme; the latter which causes Tyzzer disease and is associated with parasites, overcrowding, high temperature, malnutrition, and stress. Infection with Cryptosporidium has also been associated with wet tail . It is only seen in immunocompromised animals .
An easy way to determine if your pet had wet tail is wetness around the hamster’s genital region. They can also become dehydrated . Other symptoms include weight loss, anorexia, messy coat, lethargy, and a hunched posture . Stress can be a contributing factor to the development of this disease . Sometimes survivors of wet tail can develop and succumb to complete or partial obstruction of the ileum . Unfortunately, it has a mortality rate of up to 90% and death usually occurs within 24-48 hours after symptoms first appear .
This infection of the lungs is probably the second most commonly occurring potentially lethal disease in hamsters . Some of the bacterium associated with pneumonia include Diplococcus sp, Pasteurella pneumotropica, Streptococcus sp. and Staphylococci sp. The Sendai virus has also been known to cause pneumonia in hamsters and has been isolated in the lungs of hamsters from pet dealers .
Mycoplasma pulmonis and Pasteurella pneumotropica are the typical causes of pneumonia in hamster colonies that are well-managed.
- Also referred to as neoplasia, the most common areas for hamsters to get spontaneous malignancy are the gastrointestinal tract, haematopoietic system, skin area, and appendages. Lymphoma is the most frequently reported cancer of the haematopietic system. Hamsters afflicted with cutaneous lymphoma may present anorexia, alopecia (patchy hair loss), and weight loss. These symptoms can result in a misdiagnosis of Cushing's disease .
- Melanomas, which occur on the skin, are frequently reported and mostly in male hamsters .
- Djungarian (winter white) hamsters contract neoplastic disease at a rate that is 5 times greater than Syrian hamsters, with most of the tumors being integumental.
- Cancer is less common in hamsters than other animals like rats, domestic fowl, and some strains of mice  but it is still frequently reported and likely goes unnoticed when hamsters unexpectedly pass away.
7. Other Infections
Hamsters can succumb to various viral, bacterial, fungal, and parasitic infections .
- Hamster polyoma virus (HaPV) causes epizootic lymphoma in young Syrian hamsters and epitheliomas in older enzootically infected hamsters; the latter develops skin tumors.
- Lymphocytic choriomeningitis virus (LMCV) in hamsters is a zoonotic disease (can be transferred to humans) that is fatal in small rodents. The symptoms are wasting, anorexia, lethargy, weight loss, convulsions, blepharitis, and hunched posture.
- Bacterial pseudomycetoma requires excision.
- Hamsters infected with Demodex criceti and Demodex aurati, which are mites, normally recover with treatment, however lack of response to treatment indicates underlying severe disease and often results in death. Such underlying factors include cancer, stress, old age, renal disease, malnutrition, and hyperadrenocorticism .
- Fungal infections in hamsters are rare .
8. Kidney Disease
Degenerative renal disease affects older hamsters and has a higher prevalence in females, with amyloid deposition formation as a concurrent event .
Some evidence suggests that hamsters fed a diet higher in protein may increase the chances of nephritis. One study concluded that hamsters fed diets that contained 12% protein had both a comparable body size to hamsters fed diets with 18% and 24% protein, but lower incidence of nephritis .
9. Polycystic Disease
This is a spontaneously occurring disease of hamsters aged one year and older where thin-walled sacs filled with fluid occur in the organs. Affected areas observed include the liver, epididymis, pancreas, and esophagus, although the liver is the most common site .
- This is a disease that can spontaneously occur in older hamsters and one way hamsters die of "old age." It involves the build-up of a substance called amyloids in the organs and they occur in the liver, spleen, kidneys, and adrenal glands of aging hamsters .
- Weight loss is a common sign of hepatic (liver) and renal (kidneys) amyloidosis.
- It is more common and more severe in female hamsters, although it is common in research facilities where overcrowding is an issue, and a lot less common in pet hamsters that are housed alone .
Diabetes is uncommon or rare in hamsters, with the exception of the Chinese hamster, particularly from inbred lines . "Dwarf" breeds of hamster are more prone to diabetes in general. It involves above normal levels of blood sugar caused by lack of production (or ineffective use) of insulin .
The symptoms of diabetes in hamsters are increased thirst, drinking, and peeing, as well as weight loss, lethargy, and strong-smelling urine. It may be possible to manage diabetes in hamsters with a special diet to extend their lives .
These are just a few of the diseases and conditions that can seemingly quickly kill hamsters with little notice. It’s important to remember that there are other possible ways hamsters can die unexpectedly and to thoroughly investigate each circumstance with an open mind. It is common to never find any evidence to make a definitive conclusion on what happened, so do not stress about the lack of answers, and if you choose to get another hamster, be sure you care for your pet to the best of your ability, paying particular attention to diet, enrichment, and enclosure design, reducing stress as much as possible.
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This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.