Age at death from natural scrapie in a flock of Suffolk sheep

This study deals with natural scrapie in a flock of Suffolk sheep being bred to maximise the incidence of the disease and shows that with succeeding generations the incubation period of the disease became progressively shorter until the flock died out. The most likely explanation for this phenomenon is considered to be an increase in the load of infection.     

Scanning electron microscopic studies of the kidney glomerulus of Pudu pudu (Molina, 1782), and a comparison with that of cattle, goats, sheep and angora rabbits

The kidney's microvascularization of the Pudu pudu is mostly similar to that of domestic animals. The renal parenchymatous arteries do not give off capsular branches. The majority of the Pudu pudu's glomerula shows spherical shape. Glomerula next to the medulla have a diameter which is an average of 25 microns larger than the diameter of those situated more peripherally. Their volume is comparable to that of the angora rabbit. The capillaries form anastomosis in the inner and outer part of the glomerulus.     

An assessment of residual ovine nematodes on pasture under maritime conditions.

Residual ovine nematode pasture infections were assessed by grazing groups of ewes and their lambs on permanent sheep and cattle pastures and by the use of tracer lambs. Ostertagia spp., Cooperia oncophora, Nematodirus spp., Chabertia ovina and Trichuris spp. eggs and/or larvae survived on pastures overwinter. Second generation Ostertagia larvae were present in greatest numbers on pasture during the latter part of August and early September. The failure of a significant build-up of Cooperia oncophora was attributed to negligible worm egg output of this species in sheep. A build-up of Nematodirus spp. on pasture was not detected in this study.     

Ocular manifestations of Rocky Mountain spotted fever in dogs

Dogs were examined ophthalmoscopically to determine the prevalence and type of ocular lesions associated with naturally acquired Rocky Mountain spotted fever (RMSF). In a consecutive series of 11 dogs with serologically confirmed RMSF, 9 had ocular involvement reflecting various degrees of vascular damage, including subconjunctival hemorrhage, hyphema, anterior uveitis, iris stromal hemorrhage, retinal petechiae, and focal areas of retinal edema and perivascular inflammatory cell infiltrate. The ophthalmic lesions generally were mild, and most resolved without complication after systemic administration of appropriate antibiotics. The high prevalence of ocular lesions in these dogs suggested that critical ophthalmologic evaluation is a useful diagnostic tool for the early detection and management of RMSF in dogs.     

Food aversion learning: ability of lambs to distinguish safe from harmful foods

We studied the ability of lambs to select safe foods in the presence of harmful foods. In a series of feeding experiments, 3- to 6-mo-old lambs were offered a choice between 1) a familiar, safe and a novel, harmful food, 2) a novel, safe and a novel, harmful food and 3) a familiar, harmful and a novel, safe food. All harmful foods were palatable feeds that had been treated with lithium chloride (LiCl), a non-lethal gastrointestinal poison. When lambs ingested a meal composed of a novel food containing LiCl and a familiar, safe food, lambs subsequently avoided the novel food. Lambs avoided the novel food even when the familiar food contained LiCl. The response of lambs varied when lambs were given a choice between a novel, safe food and a novel food containing LiCl. Lambs either avoided the novel food containing LiCl and ingested the safe food or they limited their intake of both novel foods. Their response was dependent on the novelty of the food containing LiCl. When a novel, palatable food contained 2% LiCl, lambs always ate some of the food, even after experiencing illness from ingesting it. Lambs experienced with foods containing LiCl displayed greater food neophobia than lambs naive to LiCl-treated foods. Thus, novelty was the major criterion that lambs used to associate foods with gastrointestinal illness.     

Cytological, Immunocytochemical and Ultrastructural Study of the Adenohypophyseal Pars Distalis of the Kid (Capra hircus): The TSH cell

The structure and ultrastructure of the adenohypophyseal pars distalis in kids of the Murciano-granadiana breed (18 males and 12 females), aged 2-3 months and with an average carcass weight of 8 kg has been studied. Techniques of staining (Tetrachrome Herlant's, and Cleveland-Wolfe) and histochemistry (PAS, PAS-OG and BA-PAS-OG) contrasted with immunolabelling (PAP) have been used. In addition an ultrastructural study has been made and nucleus and cytoplasm, secretory granules, mitochondria and lysosomes have been measured with a semiautomatic image analyzer (IBAS-1). TSH cells are found in sagittal section in the anterior area and in an antero-caudodorsal band, and transversally in the ventral and medial region; they are 6% and their average size is 14.15 microns. Ultrastructurally they are a single cellular type with spherical granules whose size is 195 nm in males and 149 in females; these granules are characterized by a clear halo and a variable electronic density. The rough endoplasmic reticulum is found as slightly enlarged vesicles with a homogeneous and moderately electro-dense content or in concentric stratifications.     

The relationships of birth weight, preweaning gain and postweaning gain with the bovine major histocompatibility system

A total of 739 cattle from nine breeds maintained at the Roman L. Hruska U.S. Meat Animal Research Center, Clay Center, Nebraska were tested for 42 class I antigens of the bovine major histocompatibility system (BoLA). Each antigen appears to be the product of a distinct co-dominant allele of the BoLA-A locus. The number of antigens present in each breed ranged from a minimum of 10 in Hereford to a maximum of 21 in Charolais cattle. There were large differences among breeds in the frequencies of antigens. The effect of each antigen on birth weight, preweaning weight gain and postweaning weight gain was estimated in a gene substitution model. Each breed was analyzed separately. There were significant effects of some BoLA antigens on birth weight, preweaning weight gain and postweaning weight gain, which is consistent with previous reports showing associations between the major histocompatibility system and growth parameters in mice, rats and pigs. However, further research is necessary to confirm these findings and to determine the biological mechanisms underlying these associations.     

Characteristics of Salmonella isolated from an outbreak of equine salmonellosis in a veterinary teaching hospital

During an outbreak of equine salmonellosis in a veterinary teaching hospital 20 Salmonella isolates were cultured from sick horses (13 isolates) or from the hospital environment (7 isolates). Three serotypes were isolated from the environment including: S. give, S. newportand S. agona. The serotypes isolated from horses included: S. give, S. newport and S. anatum. Examination of antibiotic profiles, presence of plasmids, production of bacteriocins and hemagglutination of erythrocytes implied a common origin for the equine and environmental isolates.