If we suspect dermatitis in a hamster, we should first exclude the possibility that what we see is simply a normal scent gland; as seen over the hips in Syrians, and mid-ventrally in male dwarves. The scent gland may appear greasy, discoloured, bald and wet if the hamster licks it, and is not necessarily a sign of inflammation or infection. It is quite normal for the gland to emit a musky scent as the male signals maturity to the female. It should be noted, however, that the scent gland can be a site of tumour formation, so if you feel the appearance of the gland has altered at all, it is worth consulting your vet.
A second common cause of skin disturbance is the sores which may be produced on the legs of hamsters who habitually use wire wheels. If you must use a wheel of this type, it will help to weave cardboard through the spokes, which will also prevent the possibility of trapped or broken legs. Please select a solid wheel if at all possible.
Having ruled out these possibilities, dermatitis does arise for several reasons in all species of domestic hamsters.
Demodex mites represent the most common cause. It should be understood that most hamsters are natural hosts to mites. The same mites may even be found on us humans! These small parasites will go quite unnoticed until the hamster is old, weakened, diseased, malnourished or stressed for one reason or another. In this situation, the hamster's immune system cannot keep these common mites at bay and they may multiply and lead to symptoms such as alopecia, scratching, crusting, dandruff and scaling of the skin. Pus is not normally seen here.
So please remember, most of our hamsters have mites - but will be quite healthy and without symptoms. This is not hygiene related, just a normal phenomenon. The symptoms described above indicate an underlying health problem.
The usual mite involved is one of the Demodex species. If this problem flares up, your veterinarian may also refer to it as "demodectic mange" or "demodiciosis". Both Demodex criceti and Demodex aurati are normal residents of hamster skin. Demodex criceti is easier to detect as it lives in the crevices of the skin surface. It looks short and squat under the microscope and can be easily scraped or picked up from a heavily infested animalís skin. Demodex aurati is not quite so easy to find. This mite lives inside the hamsters hair follicles and may take several samples to find it, when it appears as quite long and tapered. Demodex aurati is the usual cause of mange in elderly or ill hamsters, and is found more often in males. Please discuss an appropriate treatment with your vet. This could include ivermectin, subcutaneously or orally (less risky and more successful!) or in severe cases, a whole body insecticidal dip. If your hamster is old or immuno-suppressed, the mites may recur eventually and the treatment will have to be repeated in order to give some weeks of relief.
In severe, untreated cases, mite infection may lay the skin open to secondary bacterial infection. This is typified by production of pus and represents an advanced state of disease. The other rare cause of so-called mange in hamsters is infection by Notoedres species of mites. This is associated with poor hygiene and is accompanied by thick yellow crusting; especially on the ears, muzzle, genitalia and paws. Pus may be produced and the hamster will appear to be very uncomfortable, mutilating itself in an attempt to alleviate the itching. Once again, it is vital to discuss the condition with your vet who may choose to treat it with ivermectin, as before, or sulphur dips Sarcoptes scabei, which causes scabies in humans, is highly infectious and may rarely transmit to hamsters. This may be treated in the same manner as Notoedric mange (above)
Very rarely, cat fleas inhabit hamsters and treatment is as for cats.
Hamsters (territorial females especially) can be aggressive leading to the infliction of wounds upon their (cage)mates. These may subsequently become infected by common bacteria such as Staphylococcus aureus and Streptococcal species. Occasionally, Pasteurella pneumotropica may be involved, but in any case prevention is better than cure and should hostile pairing result in damage, veterinary attention should be sought such that a good antiseptic can be recommended for bathing the affected are and occasionally, antibiotics can be prescribed.
Hamsters kept in enclosed cages have decreased ventilation. This is a major factor in ANY disease process and as far as dermatitis is concerned, can lead to an increased tendency to fungal infections, which like a damp environment.
Trichophyton mentagrophyes, Microsporum canis and Microsporum gypseum are the culprits here, causing "ringworm" which has NOTHING to do with any worms, only the shape of the infected area. This dermatitis will be "damper" than that caused by mites, resulting in alopecia, yellow flaky skin and often inflammation and pus.
This leaves non-specific dermatitis, which is seen quite commonly in elderly hamsters. This can simply be an indication that your hamster is not in the prime of its life or may be lacking somehow. Hamsters who consume less than 16% protein in their diet may suffer hair loss. This underlines the importance of giving your animals a balanced, professionally devised diet -rather than "treats". Like many humans, given a choice, hamsters won't necessarily select what is good for them!
Hormonal problems, especially in the elderly hamster, can lead to hair loss. Typically this is patchy, bilaterally symmetrical and leaves the rest of the hair quite healthy and thick. This could be caused by tumours in the endocrine (hormone producing)glands, or more seriously, by renal failure in the old hamster. It is also seen as a symptom of overactive and underactive thyroid problems in the elderly animal and may not be treatable. 1-2 drops of cod liver oil and a daily crushed yeast tablet have been reported to decrease hair loss in the elderly hamster and certainly will not do any harm. Unfortunately, the hamster bedding available to us is not always suitable for every animal and sensitivities do occur. This may be due to a totally unsuitable bedding, such as cedar shavings or dyed paper. Sometimes, however, a hamster may be allergic to a substance which would not affect his fellow hamster. The animal may show any of : sustained scratching, dermatitis, sneezing, eye discharge, swollen feet, pussy skin, flaky skin and hair loss (in any combination).
Allergy is more common to certain substances such as the bedding described above, food containing dyes (the "red/orange/green" bits that don't look quite natural....) and substances we introduce into the air like perfumes, cigarette smoke and furniture polish. It is surprising how sensitive a hamster may be to air borne pollutants until we consider exactly how small they are compared to us. There is no need to screen for potential allergens if your hamster seems well, only if symptoms occur. It has been said that a diet high in cereals such as oats and sun flower seeds can encourage an allergic response. In an allergic hamster, these may be replaced with boiled rice, puffed rice cereal and fruit/ veg for a reduction in symptoms. So should your hamster display skin problems, they are most likely to be caused by age, mites, allergy or a combination of all three. Please consult a vet as dermatological treatment is cheap and effective and it really is inexcusable to ignore such discomfort in your pets, who are your responsibility
Liz Newbery Johnson
BSc(Hons) Microbiology, MRes. (Biomedical research) Currently studying at Glasgow Vet School.
Editorís apologies : the following acknowledgements relating to the Papova Virus Article were omitted from the Winter Journal
Please can I acknowledge my main source text:
Pathology of Laboratory Rodents and Rabbits. Authors: Percy & Barthold ISBN 08138 2551-2 -containing an excellent, comprehensive chapter on hamster husbandry and pathology, which I would recommend to interested parties.
Many thanks also to friends and researchers at Glasgow Vet School, particularly Professor Os Jarrett and Dr Joyce Ferguson.