Diamine oxidase（DAO）has been used as a marker of intestinal villous damage in human medicine. In this study, we investigated whether serum DAO activity was decreased in Japanese Black calves with diarrhea in comparison with healthy calves. Sixty-four Japanese Black calves（10.9 ± 3.1 days old）were divided into a diarrhea group（n = 25, 10.8 ± 3.5 days old） and a control group（n = 39, 11.0 ± 2.9 days old）according to the presence or absence of diarrhea, and serum DAO activity was measured. As a result, the serum DAO activity in the diarrhea group was significantly lower than that in the control group［70.3（50.3-107.2） IU/mℓ vs. 164.2（58.1-361.2）IU/mℓ, p<0.01］. Receiver operating characteristic analysis evaluating the diagnostic ability of DAO activity for diarrhea revealed a cutoff value of 107.2 IU/mℓ, and the sensitivity and specificity were 84.6% and 100.0%, respectively. The results of this study suggest that the development of diarrhea leads to the reduction in serum DAO activity in Japanese Black calves.

　In order to identify the within-farm prevalence of Mycoplasma bovis, we investigated 10 farms that were positive for M. bovis in bulk tank milk. We collected nasal swabs from calves and pneumonia cows and vaginal swabs from postpartum cows and interviewed farms regarding the onset of pneumonia and milk infection. When M. bovis was detected from nasal or vaginal swabs, pulsed-field gel electrophoresis （PFGE） was performed to determine the epidemiological association with M. bovis detected in the milk. In 4 of the 10 farms investigated, M. bovis was detected in milk but not from nasal or vaginal swabs. Since pregnant cows were introduced from markets into these farms, these cows were suspected of being a source of infection. In the remaining 6 farms, M. bovis was detected from nasal swabs of calves or cows or from vaginal swabs of postpartum cows. Their PFGE patterns were consistent with those of milk samples at each farm. These results suggest that milk infection with M. bovis can occur not only by introduced cows, but also through the lochia in postpartum cows as well as calves and cows with pneumonia in the farm. It is important to take appropriate measures to prevent transmission through these animals.

　A 3-month-old Holstein heifer presented with diarrhea. The diarrhea and associated symptoms were initially transient and alleviated by antibiotics and anti-flatulents, but repeated recurrence was observed with progressively poorer growth. At 9 months of age, a target-like sign was observed on the right side of the abdomen by ultrasound examination. In the same month, the heifer was euthanized due to poor prognosis, and a necropsy was performed. The necropsy revealed invagination of a part of the ileum and the entire cecum into the colon. At the site of intussusception, marked hyperemia, hemorrhage or necrosis was not observed, but large capsulated abscesses were noted and suspected of being a cause of intussusception. Typically, intussusception presents with severe and acute symptoms such as colic and collapse. However, the present case suggests that intussusception could manifest as non-acute signs such as chronic diarrhea and poor growth in cattle.

　A 238-day-old Holstein-Friesian heifer weighing 247 kg suffered a closed oblique fracture of the left radius and ulna and underwent transfixation pinning and casting （TPC） with a closed approach. The heifer was sedated with xylazine （0.2 mg/kg）, placed in a supine position and administered a continuous infusion of medetomidine （20μg/kg/hr） during surgery. A brachial plexus block with 10 ml of 2% lidocaine was used to control pain. The fracture was reduced manually by longitudinal traction of the forelimb, and the fracture site of the radius was held using two bone reduction forceps. Two 4.0-mm pins were inserted into the radius percutaneously both proximally and distally to the fracture site using a power drill. Three 4.0-mm pins were additionally inserted percutaneously across the fracture plane to stabilize the fragments. A full-limb cast was applied over the pins. The pin ends were cut at the level of the cast surface and joined together with resin. The surgery was completed in 90 min. The heifer was able to bear weight on the left forelimb and returned to the farm on the day of surgery. The heifer was separately housed in a small pen. TPC was well-tolerated and required minimal assistance for standing. An antibiotic（ cefazolin） was administered for seven days. To promote weight bearing, the distal part of the cast was truncated above the carpal joint 48 days after surgery, and TPC was removed 80 days after surgery under sedation. The heifer was able to stand and walk without lameness.

　Although high success rates have been reported with internal fixation for bovine radial and ulnar fractures, TPC was beneficial for this heifer because of the lower cost, lower risks and fewer complications. While body weight can affect prognosis, the number, diameter and design of pins as well as cast length can affect firmness of the fixation and stability of the fracture ends in bovine fracture repair. Although the use of TPC is rarely reported for radial and ulnar fractures in cattle with heavier weight, the present case suggests its promising role.