Observations of sacrocaudal fusion in Greyhounds and other dogs.

OBJECTIVES: To describe the incidence and forms of nonpathological sacrocaudal fusion in racing Greyhounds and compare them with those in a variety of other domestic dog breeds. METHODS: This retrospective observational study used archived anatomical specimens from 81 racing Greyhounds and 10 Beagles, and archived clinical radiographs from 81 non-Greyhound dogs representing 37 other breeds. Dogs less than two years of age and dogs with evidence of soft tissue or osseous pathology involving the sacrocaudal region were excluded. The incidence of osseous sacrocaudal fusion (any type and complete fusion) was compared between Greyhounds and all of the other dogs combined, using the Fisher's exact test. RESULTS: Sacrocaudal fusion of some type was found in 33 (41%) of 81 Greyhounds but in only 14 (15%) of 91 non-Greyhound dogs (p <0.01). Complete fusion (osseous fusion of vertebral bodies and both transverse and articular processes) between the sacrum and the first caudal vertebra was the most common form in Greyhounds, found in 27 (33%) of 81 Greyhounds, but in only three (3.3%) of 91 non-Greyhound dogs (p <0.01). CLINICAL SIGNIFICANCE: Sacrocaudal fusion appears to be more prevalent in Greyhounds than in other domestic dog breeds and may be attributable to selection pressure for speed on a region of the spine that is naturally prone to variation. Its significance for performance and soundness requires further study.

Phagocytic capacity of leucocytes in sheep mammary secretions following weaning.

Lactating animals are particularly susceptible to mastitis during the early stages of mammary gland involution following weaning. In this study we compared the phagocytic capacity of cells collected from sheep mammary secretions at different stages of involution. The ability of neutrophils and macrophages to ingest latex beads in an in vitro phagocytosis assay was found to be dependent on how heavily the phagocytes were loaded with milk constituents. There was a decline in the phagocytic capacity of neutrophils from 1 to 2 days after weaning, while macrophages collected from fully involuted glands were more effective phagocytes compared with earlier stages (7-15 days) of involution. In addition, dendritic cells present in fully involuted mammary gland secretions (30 days after weaning) were highly phagocytic. These studies demonstrate that neutrophils and macrophages in sheep mammary secretions at early stages of involution are incapacitated, and as such may compromise the immune status of the mammary gland.