Charles Chen, Fu-Mei Kao
Charles Small Animal Clinic,
1st Floor, No. 13, Lane 171, Section 2, An-Ho Road, Taipei, Taiwan, Republic of China
Infestation with Demodex aurati and Demodex criceti was diagnosed in a twenty-four month old male hamster. Skin lesions were characterized by alopecia. Moderate scaling on the dorsal aspect of the thoracolumber and head, mild pruritus were evident. Both Demodex aurati and D. criceti were revealed from the skin scrapings. After six weeks of amitraz dip’s treatment, skin scrapings were found negative and hair regrowth appeared. The hamster was relapsed demodectic mite infestation nine months later, only D. aurati were found from skin scrapings. This is the first reported case describe the demodicosis in Syrian hamster in Taipei.
Demodectic mites are normal fauna of many mammalian species including the human’s skin. It is a very host-specific ectoparasite. In the author’s, clinic canine demodicosis comprises about 2.1 per cent of all out-patient.3 A case of a short-tailed demodectic mite and the Demodex canis infestation in a Chihuahua dog has been diagnosed and reported by the author.4 This is the second demodicosis case other than Demodex canis reported by the author and reported in the Republic of China.
Demodicosis is the most common ectoparasite found in hamsters. 1,2,5,6,7,11,12,13,14,15 The Demodex criceti (80-100µm long, short blunt abdomen, inhabits the keratin and the pits of the epidermal surface) and D. aurati (150-200µm long, cigar-shape, a hair follicles inhabitant) are normal residents found on the hamster. Mixed infestation are commonly seen in aged hamster, and are usually associated with immunologic abnormalities, malnutrition, concurrent disease, cancer, and exposure to carcinogens.10 Typical lesions are usually moderate to severe alopecia often accompanied by a variable of scaling and erythema. The lesions are most commonly revealed on the dorsal lumbosacral area, but may be generalized. Pruritus is usually absent. Diagnosis should confirmed by doing skin scrapings. Treatment with amitraz dips (0.06%) weekly is reportedly effective for the demodicosis of the hamster.1
On September 11, 1995, a twenty-four month old male hamster was presented to the Charles Small Animal Clinic, because of a severe and progressive of alopecia. A physical skin examination revealed alopecia and scaling on the dorsal aspect of thoracolumber and head. No specific findings on direct KOH preparation. Result from a Wood’s light examination was found negative fluorescence reaction. Larvae, nymph and adult forms of Demodex aurati and only one adult form of Demodex criceti were revealed from the skin scrapings of the alopecia area. The hamster otherwise was healthy. Demodicosis was diagnosed. The hamster was treated with weekly amitraz dips (0.04%). After six weekly dips, the hamster’s skin condition showed remarkable improvement. The skin scrapings were negative, and the hair regrowth was normal. Three months later, the hamster’s condition remained normal and did not show signs of concurrent diseases or cancer.
The Syrian hamster is a popular exotic companion animal in Taiwan. Skin diseases of hamsters are rarely reported. A fungal infection case, caused by Microsporum canis was only reported recently.8 Skin diseases of exotic companion animals such as the guinea pig, rabbit, mice and hamster can be viewed as a new type of challenge for small animal practitioners in Taiwan.
The average life expectancy of a hamster is one to three years,12 twenty-four months is the average life span for aged hamster. Demodicosis in young animals is usually because of rapid growth, malnutrition, breed predilection or an immune depress condition. In aged animals, this is always associated with internal diseases or tumors. Demodicosis in older hamsters is reportedly associated with immunologic abnormalities such as malnutrition, concurrent diseases, cancer, and exposure to carcinogens. However conditions that will induced young hamster demodicosis were rare discussed. Recently, hamster demodicosis was discussed in internet. Anna Meredith (University of Edinburgh) think that in her experience 1) after correcting the husbandry condition (diet, housing, bedding), young hamster with alopecia lesions which caused by demodectic mite, hair will regrowth without any specific treatment for the mites. 2) If scrape normal hamsters, they have mites too.16 Andrew Wilson point out that some think that demodectic mites in hamster may be secondary to Cushing’s disease.17 The character and importance of demodectic mites of hamster’s alopecia seems still confused and seems had not confirmed. This studied hamster had a high quantity food, good housing and bedding condition, and did not have a history of exposure to carcinogens before onset the infestation. It also did not show any concurrent disease or cancer within and after treatments one year later.
It has been suggested that several skin scrapings should be routinely carried out for every dermatologic case. In hamster’s case, skin scrapings usual will induced iatrogenic traumatic lesions on the hamster’s thin skin. It is suggested that the examiner gently squeeze the scraping area before scrapings. This will reduced the severity of trauma, and easily reveal demodectic mite. Currently no studies tell us about the existence ratio of the two species of mites found on a hamster’s skin. In this case, over 50 adult form, about 10 larvae and 20 nymph forms of D. aurati were found from four scrapings. However only one adult form of D. criceti was found. This is something, worthy of note and further study.
In conclusion, a hamster with mixed infestation of D. aurati and D. criceti has been reported here. Larvae, nymph and adult forms of D. aurati, and an adult form of D. criceti was revealed from skin scrapings. The authors selected amitraz dip for treated hamster’s demodectic mites infestation. Thought the effectiveness of amitraz is preserved but it is quite safe used for hamster on the concentration of 0.04~0.06%.
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- Chen C. Synopsis of Veterinary Dematology in Taipei. Proceeding of the XX Congress of the World Small Animal Veterinary Association. Yokohama, Japan, 1995
- Chen C. A Short-tailed Demodectic mite and Demodex canis infestation in a Chihuahua dog. Veterinary Dermatology 6(4) 1995 227-229
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- .Peter Hill, Post Anna Meredith’s opinions at firstname.lastname@example.org.
- Andrew Wilson, Post at email@example.com.