This study aimed to determine whether serum is suitable for reverse transcription polymerase chain reaction (RT-PCR) detection of persistent infection (PI) of bovine viral diarrhea virus (BVDV) in calves that have maternal colostral antibodies. In addition, evaluation of availability of pooled serum for use as a screening method for the detection of cows with PI was also examined. To investigate these aims, we developed a quantitative, real-time RT-PCR for the detection of BVDV. Quantitative studies showed that the minimum value in PI calves that have colostral antibodies was 2.17×10⁴ copies, which was higher than the detection limit for RT-PCR (approximately 6.25×10³ copies) ; however, the copy number in the serum was significantly low and the antibody titer was high. This suggests a transient decrease in the copy number due to colostral antibodies. The RT-PCR of pseudo-pooled serum using PI sera and fetal bovine serum showed obscure detection of the specific target band in diluted samples from low-copied PI serum. Our study indicated that calf serum with colostral antibodies would be a useful diagnostic material for the RT-PCR detection of PI with BVDV ; however, pooled serum might be affected by a transient decrease in BVDV copy numbers due to colostral antibodies.

A spayed, female Shetland sheepdog diagnosed with Hansen type II intervertebral disc disease showed progressive ataxia and loss of bark. Superoxide dismutase (SOD) 1 mutation analysis confirmed homozygous mutation. The dog died from insufficient breathing on day 859, necropsy was carried out, and histology of the brain and spinal cord was examined. Histopathological examinations revealed myelin loss, axonal degeneration, and diffuse proliferation of astrocytes in the spinal white matter, as well as neuronal loss and chromatolysis of remaining neuronal cells in the ventral horn. These lesions almost conform to those of canine degenerative myelopathy (DM). For Shetland sheepdogs with homozygous SOD1 mutation and symptoms of progressive ataxia, canine DM should be considered as a possible differential diagnosis.

Lethal viral hepatitis associated with adenoviral infection has been reported in some otariid species. There was also an outbreak reported from an aquarium in Japan. Severe acute hepatitis was present in two California sea lions and a novel adenovirus was detected. It has been suggested that early treatment may be successful in saving the animal. Attention must be paid to sanitary management, because persistent viral infection was observed after the symptoms had disappeared.