The First Outbreak of Chorioptes texanus (Acari: Psoroptidae) Infestation in a Cattle Farm in Korea

Mites in the genus Chorioptes cause a mild form of skin disease in both domestic and wild ruminants. In July 2006, dermatitis characterized by alopecia, marked lichenification, accumulation of crust, and fissuring was recognized in 14 out of 200 Holstein dairy cattle raised in the cattle farm of the National Institute of Animal Science in Cheonan, Republic of Korea. Skin lesions were distributed mainly over the tail base, and sacral and perineal regions. Microscopic examinations of skin scraping samples from severely affected areas revealed numerous mites of all developmental stages. Morphologically, pedicels of the mites were short and unjointed. The tarsal suckers occurred on the pedicels of all the legs in the male worm and on the first, second, and fourth pair of legs in the adult female worm. A single long seta at the tarsus of legs III and the length of legs II being about twice as long as legs IV in adult male mites were observed. Arising anterior to the inner-most spatulate seta was a short seta with an average of 26.4 +/- 5.8 micrometer in length. Also, the length of setae #4 on the opisthosomal lobes was relatively short. Based on these observations, the mites were identified as Choriptes texanus. Although the chorioptic mange may not influence the mortality rate in the affected farm, reports indicate that a decline in milk production can be observed. This is the first report of chorioptic infestation in a cattle farm from Korea.

Comparative analysis of heart functions in micropigs and conventional pigs using echocardiography and radiography

The production of miniature animals has been suggested for use in organ transplantation. At present, many of the studies about application of animal organs to human have been focused on pigs because of the number of advantages involved and due to their similarities with human. However, a physiological analysis of the organs to be transplanted has not yet been carried out. Therefore, this study analyzed whether or not there were physiological and morphological differences in the hearts of conventionallyreared pigs and micropigs. In this study, the morphological and physiological functions of the heart were examined using radiographic and echocardiographic equipment. In the lateral radiographic view, the heart of the micropig has a larger cardiac long axis : short axis ratio than does the conventional pig, but the difference in the vertebral heart score was not significant. In addition, there were no morphological differences on the X-ray fluoroscopic view. There were no differences in echocardiographic values, except for several values in the left ventricle traces. Overall, it is expected that the values measured in this study will contribute to understanding of the physiological characteristics of micropigs.

Establishment of a bovine leukemia virus-free dairy herd in Korea

In view of the high prevalence rate of bovine leukemia virus (BLV)infections in cattle over the entire country, a large dairy farm in Chungnam province was chosen and 'test and segregate' program was instituted. On July 1999, ELISA test was performed on 491 animals on the farm and only 163 cattle (139 adult cows, 18 female and 6 male calves)were BLV-seronegative. From February 2000 through April 2004, the seronegative group was placed in barns 1,500 to 2,000 m from seropositive group and thereafter tested at 3-to 5-month intervals by ELISA. Animals seroconverted in consecutive tests were removed from the seronegative group immediately after the detection of anti-BLV antibodies. The changes in management were aimed at preventing iatrogenic transfer of blood between cattle. Replacement heifers imported from other countries and calves born at the farm were repeatedly tested by ELISA, and only seronegative animals were introduced into the group. As of April 2004, there were 311 cattle in the BLV seronegative group of the farm. Twent y four cows of the initial 139 adult cows were seroconverted in 2000, and no seropositive animals were found since February 2001. Follow up of the group, from which all seropositive cattle were moved to a separate location, revealed no recurrence of BLV infection for three years. The approach in the present study might be valuable for Korean producers who would like to move toward a BLV-negative status.

Differences in the serum immunoglobulin concentrations between dairy and beef calves from birth to 14 days of age

The changes in serum levels of immunoglobulins G, M and A of dairy and beef calves of well-managed herds were monitored from birth to 14 days post partum using single radial immunodiffusion. Serum levels of all three immunoglobulin classes reached its peak at 24 hours in both groups of calves after birth, at which time there were very high levels of each immunoglobulin present. The mean IgM and IgA levels of the two groups became same at 6 days and 8 days of age, respectively but the mean IgG level of beef calves was approximately twice that of dairy calves throughout the experiment.

A survey of canine heartworm infections among German shepherds in South Korea

A survey of canine heartworm (Dirofilaria immitis) infections among German shepherds in five areas of South Korea was performed from October 1994 to August 1995 using a microfilarial test (modified Knott's test) and an antigen test (DiroCHEK , Synbiotics, USA). The infection rate of 127 German shepherds (71 males and 56 females) was 10.2% (13/127) by the microfilarial test, but was 28.3% (36/127) by the antigen test, revealing that 24 of the 36 antigen-positive dogs were microfilaria-negative in the peripheral blood. All dogs that were microfilaria-positive were also antigen-positive. Three of the microfilaria-negative and antigen-positive dogs contained 4 - 15 adult heartworms in the heart and pulmonary arteries upon necropsy. The infection rate among German shepherds was the highest in Hoengsong-gun (Kangwon-do, 84.4%), while those of Yechon-gun (Kyongsangbuk-do) and Chungwon-gun (Chungchongbuk-do) areas were 20.0% and 14.3%, respectively. None of the dogs in the Kimhae-shi (Kyongsangnam-do) and Kwangju areas was heartworm positive. The infection rates of heartworm in dogs at the age of 1-3, 4-6, and 7-11 years were 6.3%, 21.4%, and 56.4%, respectively. Based on the fact that the antigen test is more accurate than the microfilarial test, this study strongly indicates that the prevalence rate of canine heartworm in Korea may be higher than previously reported (3.1+=23.0%) which utilized microfilarial tests.