Liver biopsy as a technique for assessing copper status of sheep

A procedure for taking biopsy samples from the ovine liver by a paracostal route is described. Samples were taken from 120 Merino rams on up to 3 occasions over a 3 month period. At the end of the period, the rams were subjected to 2 further biopsies and were then slaughtered, and the liver was removed and homogenised. Copper contents of all samples were determined.
Frequency of biopsy did not affect hepatic copper concentration which was significantly overestimated by the biopsy method by approximately 5%. Variability associated with the biopsy procedure was approximately ± 30 to 40 mg Cu/kg DM (SD) and was small relative to variability between animals. Experimental designs were preferred in which samples are taken before and after treatments are applied; changes in concentration are then analysed. Such analyses eliminate errors associated with variability between animals and the small bias in the sampling procedure. Liver biopsy did not significantly reduce bodyweight or the rate of gain.     

Suitability of synthetic alkanes as markers for the estimation of passage rate in sheep

An experiment was conducted with eight adult wethers housed individually in metabolism crates to determine the suitability of alkanes to serve as passage rate markers in sheep. Two diets consisting of lucerne (800 g DM/d), without (treatment ‘Lucerne’) and with coarse maize meal (270 g DM/d; treatment ‘Lucerne–Maize’) were fed to four sheep per diet twice daily in equal proportions. Lucerne fibre was prepared from chopped lucerne silage and mordanted with chromium during 24 h cooking with sodium–lauryl–sulfate (Chromium–mordanted lucerne fibre: LF-_Cr). The synthetic alkane C36 was dissolved in heptane and sprayed onto lucerne fibre which had been similarly prepared (LF-_C36). C28 was dissolved in heptane and sprayed onto maize meal (M-_C28). Markers were fed at the same time as a pulse dose. For a period of 10 days, rectal grab faeces samples were taken in intervals of increasing length (2–12 h). A multi-compartment-model was fitted to the marker excretion curves.Maximum marker excretion appeared earlier for alkane markers than for Cr in both treatments. Within treatment Lucerne no significant differences between Cr and C36 were detected for Rumen mean retention time (MRT) (P > 0.05). Numerical differences were observed for RumenMRT in treatment Lucerne–Maize between LF-_Cr and LF-_C36 and M-_C28 (33, 25 and 25 h), respectively. Further numerical differences were observed in CaecumMRT for LF-_Cr and LF-_C36 in treatment Lucerne and for all markers in Lucerne–Maize. In treatment Lucerne, faecal recoveries of markers LF-_Cr and LF-_C36 were 95 and 85%, in treatment Lucerne–Maize 101 and 88%, and for M-_C28 in the treatment Lucerne-Maize only 75%.It was shown that the lower faecal recovery of alkanes by itself does not cause biased estimates of passage rate parameters. However, further investigations are necessary to determine the relationship between the time a particle has spent in the digestive tract and the disappearance of the alkane marker, as this could introduce a bias to the estimate.The major shortcoming of alkanes as passage rate markers seemed to be migration between solid and liquid phases of the digesta. This problem could be overcome by new labelling procedures or the use of ¹³C-labelled native alkanes.     

Suitability of the cranial portion of the vagina as a site for measurement of intra-abdominal pressure variations in dogs

OBJECTIVE: To determine whether the cranial portion of the vagina of dogs is a suitable site for measuring intra-abdominal pressure during cystometry. ANIMALS: 16 bitches (8 sexually intact and 8 spayed). PROCEDURE: 2 types of vaginal catheters were used to measure intra-abdominal pressure changes in anesthetized dogs. Catheters were inserted in the rectum and cranial portion of the vagina. RESULTS: Intra-abdominal pressure variations were detected with greater magnitude in the rectum than the cranial portion of the vagina, regardless of type of catheter used and reproductive status (sexually intact vs spayed) of the dogs. CONCLUSIONS AND CLINICAL RELEVANCE: The rectum was the better site for measuring intra-abdominal pressure changes in female dogs. Measurement of intra-abdominal pressure with concomitant measurement of intravesical pressure to determine detrusor pressure during cystometry in female dogs is more reliably detected from the rectum than the cranial portion of the vagina.     

The sheep and cattle Peyer's patch as a site of B-cell development

In sheep and cattle, the ileal Peyer's patch (PP), which extends one-two meters along the terminal small intestine, is a primary lymphoid organ of B-cell development. B-cell diversity in the ileal PP is thought to develop by combinatorial mechanisms, gene conversion and/or point mutation. These species also have jejunal PP that function more like secondary lymphoid tissues concerned with mucosal immune reactions. These two types of PP differ significantly in their histology, ontogeny and the extent of lymphocyte traffic. The prenatal development of follicles in the PP begins first in the jejunum during the middle of gestation and then in the ileum during late gestation. B-cells proliferate rapidly in the ileal PP follicle; up to five percent of these cells survive while the majority dies by apoptosis, perhaps driven by the influence of environmental antigen and/or self-antigen. The surviving cells migrate from the ileal PP and populate the peripheral B-cell compartment. By adolescence, the ileal PP has involuted but the function of jejunal PP, compatible with a role as secondary lymphoid organ, continues throughout life. In this review, we focus on the development of PP as a site of B-cell repertoire generation, positive and negative B-cell selection, and the differences between ileal PP and jejunal PP.     

Demonstration of lateral transmission of scrapie between sheep kept under natural conditions using lymphoid tissue biopsy

Scrapie free adult sheep were introduced to a sheep flock specifically maintained to maximise scrapie infection. Native born sheep of the highly susceptible VRQ/VRQ genotype in this flock show highly efficient transmission, evidenced by 100% infection, with an age at death of less than 2 years. Infection in introduced sheep was identified by biopsy of tonsilar and nictitating membrane lymphoid tissue. Progeny of these sheep were monitored and clinical disease confirmed by examination of the brain using routine diagnostic methods. Na?ve sheep of New Zealand origin introduced to the flock in adulthood became infected, demonstrating that lateral transmission had occurred. Lambs born to introduced ewes became infected and died at the same age as lambs born to native ewes, consistent with lateral transmission of scrapie to lambs. Although maternal transmission cannot be totally excluded for the lambs in this study, the data are consistent with lateral transmission being the most important means of spread leading to the high incidence of scrapie observed in this flock.     

Mucosa-associated lymphoid tissue lymphoma of the third eyelid conjunctiva in a dog

A 4-year-old, neutered female Cocker Spaniel was presented to the veterinary clinic for protrusion of the left third eyelid. When the third eyelids from both eyes were everted, lobulated masses were present on the bulbar surface. The left third eyelid had a larger protrusion. There was no apparent associated ocular or systemic involvement. The tumor of left third eyelid was removed and referred for histological examination. Histologically, there were proliferations of lymphoid follicles surrounded by lymphoid cells forming a marginal zone. Those lymphoid cells occasionally infiltrated into conjunctival epithelium. A few apoptotic bodies with karyopyknotic and karyorrhexic nuclei were observed in the germinal center of lymphoid follicles. Mitotic figures were rare. On immunohistochemistry, tumor cells expressed CD79a but not CD3. A diagnosis of extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) of the third eyelid was established based on the histological and immunophenotypical features. At the 1-year follow-up, there was no evidence of recurrence of the mass at the area of excision of the left third eyelid and the remaining tumor of the right third eyelid was still a similar size. The dog still showed no significant findings, except those of the tumor, and no evidence of systemic involvement. To the authors' knowledge, this is the first reported case of MALT lymphoma of the third eyelid in a dog.     

Scrapie in the sheep and laboratory animals: Suitability of the sheep model for the study of slow virus diseases

After briefly summarizing the information available on sheep scrapie, the authors explain the value of using the sheep in the study of slow virus diseases, since it is particularly prone to diseases of this type. It may be affected not only by scrapie but also by other similar diseases such as visna, maedi and jaagsiekte. These disorders may therefore be used as models to which the most recent pathogenic concepts can be applied. A study of them will lead to a better understanding of the virus-host relationship in the pathology of infection.

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Kurzfassung Im Anschluss an die Darstellung der Traberkrankheit bei Schafen und eine kurze Zusammenfassung aller bisher darüber vorliegenden Erkenntnisse wiesen die Autoren auf die Bedeutung des Schafes als Versuchstier bei der Untersuchung der durch langsame Viren verursachten Krankheiten hin, da Schafe eine ausgeprägte Disposition für diese Art von Störungen aufweisen. Sie können neben Traberkrankheit ausserdem von weiteren Erkrankungen des gleichen Typs wie Visna, Maedi und Jaagsiekte befallen werden. Diese Erkrankungen eignen sich daher als Modelle, an denen sich die jüngsten Erkentnisse über die Pathogenese praktisch erproben lassen. Solche Untersuchungen führen zweifellos zu einem besseren Verständnis des Verhältnisses zwischen Wirtstier und Virus im Rahmen der infektiösen Pathologie.

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Resume Après avoir montré l'importance et résumé brièvement l'ensemble des connaissances relative à la tremblante du mouton, les auteurs montre l'intérêt de l'utilisation du mouton pour l'étude des maladies à virus lents, celui-ci montrant une particulière prédisposition à présenter ce type de désordres. Il peut être atteint non seulement de tremblante mais aussi d'autres maladies de même type comme le visna, le maedi et la jaagsiekte. Ces affections constituent donc des modèles auxquels les plus récents concepts pathogéniques peuvent être appliqués. Leur étude permettra certainement de mieux comprendre la relation virus-hôte en pathologie infectieuse.

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Riassunto Gli autori, dopo aver sottolineato l'importanza e riassunto brevemente il complesso dei dati disponibili sulla malattia del trotto (prurigo lombare accompagnata da disturbi neuromotori) degli ovini, rilevano l'interesse che può avere l'impiego di ovini nello studio delle malattie da virus lenti, in quanto questi animali sembrano particolarmente predisposti a tale tipo di affezioni. Essi possono essere colpiti non soltanto dalla malattia del trotto, ma anche da altre malattie affini quali il visna, il maedi e la jaagsiekte. Lo studio di queste malattie, che rappresentano modelli ai quali possono essere applicati i più recenti concetti patogenetici, consentirà certamente di comprendere più a fondo la relazione virusospite nella patologia infettiva.

     

The effect of an intrauterine viral infection on the skin follicles of sheep

Border disease of sheep is a transplacental viral infection of the foetus. In medium and fine fleeced breeds, the most consistent of the pathological changes is permanent primary follicle enlargement, first apparent at 115 days gestation and accompanied by increased fibre size and frequency of fibre medullation. A tendency for fewer secondary follicles to develop in Border disease is probably an indirect consequence of infection.Primary follicles are only susceptible to the effects of Border disease following maternal inoculation with standard inoculum up to 80 days gestation. The subsequent resistance of primary follicles may be related to a loss of susceptibility with differentiation or, more probably, to the development of a foetal immunological response to the agent.In coarse fleeced breeds, the skin appears to be unaffected by Border disease. It may be that Border disease de-inhibits follicle growth limiting mechanisms in finer fleeced breeds, causing reversion to a more primitive, coarser fleece type.     

Inhibition of the development of Trichostrongylus spp. as third stage larvae in sheep

In non-lactating Frisian ewes slaughtered in September and November 1975 and in ewes slaughtered in March/April 1976 at lambing, the majority of Trichostrongylus axei, T. vitrinus and T. colubriformis found were inhibited third stage larvae (L₃). However, some larvae at various stages of development were found in the animals slaughtered at lambing. In contrast, in lactating ewes slaughtered 6 weeks after lambing in April 1976, almost all Trichostrongylus spp. appeared to be adults. All ewes grazed a pasture heavily contaminated with gastro-intestinal nematodes from June 1975 until at least 2 weeks before necropsy.In lambs on the pasture from April or June 1975, and slaughtered in September and November 1975 and March 1976 after at least 2 weeks of isolation, only small proportions of the Trichostrongylus spp. populations appeared to be L₃. Similar results were obtained from tracer lambs kept at pasture from August 1975 to March 1976. The implications of these findings are discussed.     

Lack of PrP(sc) immunostaining in intracranial ectopic lymphoid follicles in a sheep with concomitant non-suppurative encephalitis and Nor98-like atypical scrapie: a case report

During active surveillance for transmissible spongiform encephalopathies (TSEs) in sheep, an initial reactor was detected using a rapid test on a brain sample. Immunohistochemistry confirmed an atypical TSE presentation that closely resembled the previously described Nor98 cases. Sequencing of the prnp gene confirmed the ARQ/AHQ genotype with the L141F mutation at codon 141 associated with this phenotype. The head, including the brain and cranial lymphoid tissues, was sampled and examined thoroughly. Non-purulent encephalitis, with ectopic lymphoid follicle formation within the brain, was diagnosed concomitant to the TSE. When scrapie-associated prion protein (PrP(sc)) deposition was studied by immunohistochemistry there was a noticeable lack of lymphotropism. The distribution of PrP(sc) in the brain differed considerably from that of classical scrapie cases. Astrogliosis and microgliosis were demonstrated by histochemical procedures.     

Suitability of poultry litter ash as a feed supplement for broiler chickens

An experiment was conducted to evaluate poultry litter ash (PLA) at graded levels (0, 25, 50, 75, and 100%) as a dietary substitute for dicalcium phosphate (dicalP) for broiler chickens, where PLA was substituted for dicalP on a wt/wt basis. A decreased BW gain was observed at 21 d from PLA at the 100% substitution rate when compared with the 25% substitution rate. No effects on BW gain, feed consumption, or FCR were incurred by study termination at 41 d, and the 100% substitution rate of dicalP did not cause any detrimental effects on the live performance in market age broilers. Although femur ash percentages decreased with increasing levels of PLA, bone integrity was not compromised by the addition of PLA to the diet. Dry matter digestibility of dietary Ca (26.32–58.65%) and P (30.23–42.68%) increased with increasing levels of PLA (0–100%), respectively, inferring that the Ca and P component of the diet was more efficiently used as the level of PLA increased. In conclusion, PLA resulting from the combustion of poultry litter can be used as a P and Ca source for broilers.     

The use of a liver biopsy technique for investigating the effects of hexacholrobenzene on some drug-metabolising enzymes in sheep.

Several parameters of drug-metabolising capacity were measured in samples taken from various regions of the sheep liver. A statistically significant difference of 10 per cent between mean values of enzyme activities of the ventral and dorsal lobes was found. This could be ignored when compared with the expected treatment effect. It is concluded that the biopsy technique provides a sufficiently representative sample of the whole liver for use in studies of the type described. The results also indicated that the liver enzyme levels of young lambs were lower than those of older lambs and adult sheep. Sheep dosed with hexachlorobenzene (hcb) showed increased activities of aniline hydroxylase and 4-nitroanisole O-demethylase but not of the NADPH-independent esterases. It is concluded that HCB induces the drug-metabolising enzymes of sheep liver.     

Suitability of canine herpesvirus as a vector for oral bait vaccination of foxes

Studies were conducted to evaluate the feasibility of using canine herpesvirus (CHV) as a vaccine vector for bait-delivered oral vaccination of wild foxes. To test the viability of CHV in baits, CHV was freeze-dried, incorporated into different baits, stored, and the remaining viral infectivity tested in cell culture after varying periods of time at different storage temperatures. Experimental baits (mouse carcasses) and commercial baits (FOXOFF and PROBAIT) were prepared with either liquid or freeze-dried CHV and tested in two fox trials for their capacity to induce CHV-specific antibodies following oral baiting. Freeze-drying and storage temperatures below 0 degrees C had a stabilizing effect to virus infectivity. When stored at -20 degrees C, freeze-dried CHV retained its full infectivity for up to 3 months in PROBAIT baits, the remaining infectivity in FOXOFF baits was 100-fold less. Oral baiting with CHV induced antiviral serum antibodies in all vaccinated foxes (20/20). None of the vaccinated foxes became ill or shed infectious virus into the environment although viral DNA was detected in body secretions as evaluated by PCR. The results indicate that CHV can be freeze-dried and stored over extended periods of time without loosing much of its infectivity. This is the first report of CHV being used for oral bait vaccination of foxes. It appears that CHV is well suited for use as a recombinant vector for wild canids.     

The sheep as a model for osteoporosis in humans

There is great interest in large animal models for studying different aspects of osteoporosis. Several laboratories around the world have used ovariectomized sheep as a model because of their ease of housing and handling, low expense compared to other large animals, availability and acceptance in society as a research animal. They have been used to study the response to new therapies for post-menopausal osteoporosis, low-magnitude mechanical stimulation, orthopedic implants in osteoporotic bone and bioactive ceramics to strengthen vertebral bodies. To produce severely osteopenic bone comparable to that seen in humans, a combination of estrogen deficiency following ovariectomy plus a calcium-wasting diet is currently being investigated.     

Melanocortin-4 receptor in sheep: a potential site for therapeutic intervention in disease models

Reduced appetite combined with increased metabolic rate and decreased lean body mass is a major consequence of disease and other stressors. Studies in rodent species suggest that an understanding of appetite regulation may provide methodologies for intervention to prevent the deterioration of body mass such as observed with cancer or infectious diseases. For example, melanocortin-4 receptor (MC4-R) antagonists have shown a remarkable ability to reverse or prevent cachexia in rodents with sarcoma or treated with endotoxin. Studies in sheep have indicated that a number of peptide neurotransmitters may have a role in regulating appetite in this species. For example, agouti related protein mRNA and protein levels are dramatically altered with fasting in sheep. Moreover, agouti related protein, neuropeptide Y, melanin concentrating hormone and orexin are potent stimuli to increase feed intake in sheep. Recent studies have indicated that one of these neurotransmitters, NPY, can work in principal to improve appetite in endotoxin-treated sheep. Current studies are examining the role that MC4-R antagonists may have in the prevention or correction of body mass wasting diseases as well as practical applications in animal production.