Imports: Current trends and usage.

Nonhuman primates are essential to the advancement of some areas of biomedical research and testing. Some populations of these species in the wild may be threatened with extinction because of habitat destruction; therefore, the biomedical community has been monitoring trends in their importation and use, and supporting various conservation activities. During the past 25 years, there has been a marked decrease in importations into the United States, a large proportion of which is the result of a 1975 ban on their importation for the pet trade. During the same period, the need for biomedical purposes has remained fairly constant. Nonetheless, the reductions in imports have been augmented by the biomedical community through reducing losses during quarantine and conditioning, ensuring a more judicious use of these animals, and by increasing the availability of animals from breeding programs both in source countries and the United States. © 1994 Wiley-Liss, Inc.

Influence of inbreeding on reproductive performance, ejaculate quality and testicular volume in the dog.

An established foxhound colony employing an outbreeding and inbreeding program was evaluated to assess the influence of increased homozygosity on overall reproductive performance and ejaculate quality. A total of 14 outbred and four inbred male dogs were naturally bred to 544 outbred and 51 inbred bitches, respectively. Mean conception rate and total number of puppies whelped and number born alive were greater (P<0.01) in outbred compared to inbred lines. Duration of gestation and number of puppies surviving from birth to weaning were not different between outbred and inbred groups. Ejaculate quality of studs also appeared affected by genotype with outbred males producing a greater (P<0.025) average sperm count/ejaculate and sperm count/ml of ejaculate. Ejaculate volume, % motility of spermatozoa and testes volume, although not significantly different, also favored the outbred compared to inbred sires. These results: 1) indicate that a breeding program utilizing dogs with inbreeding coefficients ranging from .125-.558 can experience reduced reproductive performance; 2) suggest that a portion of the infertility associated with conception may be attributed to the male, since inbred studs produced lower quality ejaculates compared to outbred counterparts.

Studies of the Pelger-Huët anomaly in foxhounds.

An inbred family of foxhounds with four members expressing the Pelger-Huët (P-H) anomaly is described. The disease-free status of all P-H affected dogs suggests a benign disorder, although review of breeding records indicated a lower percentage of pups weaned (63%) by P-H females compared with the percentage of pups weaned (81%) by outcrossed females throughout the foxhound colony. Light-microscopic examination of blood films from affected dogs revealed 50--67% neutrophils with round, oval, or bean-shaped nuclei and rarely (0.5%) segmented nuclei. Neutrophils examined by electron microscopy showed the nuclei to have a fine nuclear cleft and condensed chromatin and the cytoplasm to have mature heterochromatic granulation. Local P-H neutrophil mobilization through a standard skin abrasion into a chamber containing autologous serum was impaired at all time periods evaluated (1, 4, 8, and 24 hours) compared with the neutrophil mobilization by normal dogs. Antibody response to sheep erythrocyte immunization was also impaired. In vitro reactivity of normal and P-H lymphocytes stimulated by pokeweed mitogen was depressed when lymphocytes were cultured in plasma from a P-H dog but not when cultured in plasma from a normal dog. Vigorous blastogenic responses to phytohemagglutinin by normal and P-H lymphocytes cultured in P-H or normal plasma suggest the presence of a factor(s) in the P-H plasma which interferes with B-lymphocyte reactivity.

Analgesia from electrical stimulation in the brainstem of the rat.

Stimulation at several mesencephalic and diencephalic sites abolished responsiveness to intense pain in rats while leaving responsiveness to other sensory modes relatively unaffected. The peripheral field of analgesia was usually restricted to one-half or to one quadrant of the body, and painful stimuli applied outside this field elicited a normal reaction. Analgesia outlasted stimulation by up to 5 minutes. Most electrode placements that produced analgesia also supported self-stimulation. One placement supported self-stimulation only in the presence of pain.