Climate change will affect the ability of forest management to reduce gaps between current and presettlement forest composition in southeastern Canada

Landscape Ecology - Forest landscapes at the boreal–temperate ecotone have been extensively altered. Reducing the gap between current and presettlement forest conditions through...     

Occurrence of Mirafiori Lettuce Virus and Lettuce Big-vein Virus in Relation to Development of Big-vein Symptoms in Lettuce Crops

Big-vein disease (BV) of lettuce has been attributed to infection by Lettuce big-vein virus (LBVV), vectored by the soil fungus Olpidium brassicae. The finding of a second soil-borne virus in lettuce, Mirafiori lettuce virus (MiLV), led to a re-investigation of the role of LBVV in big-vein disease, with evidence emerging that both MiLV and LBVV are vectored by O. brassicae, and that MiLV, not LBVV, is the cause of BV (Lot et al. (2002), Phytopathology 92: 288–293). The two viruses have coat proteins of similar size but have different morphologies and are serologically unrelated. We tested individual lettuce plants in BV-prone fields and protected crops in France and Italy for the presence of the two viruses, using DAS-ELISA and antisera specific for each virus. Both MiLV and LBVV were found at high incidence, often together but sometimes separately. Symptoms were frequently found to be associated with MiLV alone or both viruses, but rarely LBVV alone. However, no absolute correlation emerged, because sometimes MiLV was present in the absence of symptoms, and vice versa. To clarify the situation, individual lettuce plants were examined over a period of time in two further surveys. In surveys of protected crops in France, plants with big-vein were always ELISA-positive for MiLV, or else symptomless plants positive for MiLV were later seen to develop big-vein symptoms. Presence or absence of LBVV appeared to have no effect on symptom development. In surveys of open fields in Italy, all combinations were found: presence of both viruses, apparent absence of both viruses, or presence of each one alone, in plants that developed BV. At the end of the observation period, nearly all plants had BV and contained both viruses.     

Ultrasound-guided core needle biopsy in dogs with thyroid carcinoma

Currently, a histological diagnosis of highly vascularized canine (c) thyroid carcinoma (TC) is primarily obtained following excisional biopsy (EB) through thyroidectomy. Non-EBs are contraindicated in unresectable invasive cTCs due to their highly vascularized nature, which subsequently, lack histological diagnosis. We hypothesised ultrasound-guided core needle biopsy (UGCNB) to be a safe biopsy technique to obtain an accurate histological diagnosis in unresectable TCs. Nine client-owned dogs with suspected naturally occurring TC, presented for surgical excision, were included. First, a UGCNB was taken from the cervical tumour, followed by EB. Haemorrhage following UGCNB was evaluated preoperatively and once the tumour was surgically exposed by visual inspection and ultrasonography. Histological analysis, including cell organisation, tumour capsular and vascular invasion, and immunohistochemistry were performed and compared between both biopsy specimens (i.e., UGCNB and EB) of the same dog. Pre- and peroperative visual inspection revealed minor, localised haemorrhage, subsequent to the UGCNB, in 7/9 dogs. Histology of the EBs confirmed TC in 8/9 dogs and was inconclusive in 1/9 dogs. Histology of the UGCNBs revealed neoplastic thyroid tissue in 7/9 UGCNBs and was inconclusive in 1/9 UGCNBs. The remaining UGCNB contained no mass related tissue and was, therefore, excluded. Histological parameters (i.e., cell organisation, tumour capsular and vascular invasion) were not concordant between 6/8 included UGCNBs and their respective EB. Immunolabelling for thyroglobulin and calcitonin was concordant between all eight included UGCNBs and their respective EB. The remaining evaluated immunohistochemical markers (i.e., cyclooxygenase-2 [COX-2], P-glycoprotein and vascular endothelial growth factor [VEGF]) were concordant between the included UGCNBs and the EBs in 6/8 dogs. To conclude, UGCNBs can be safely obtained in suspected cTCs and enable a reliable diagnosis of the thyroid origin, thyroid cell origin and potential therapeutic markers such as COX-2, P-glycoprotein and VEGF. Subsequently, UGCNB enables clinicians to establish an individually tailored treatment plan in dogs with unresectable TC.     

Difference in factors explaining growth rate variability in European eel subpopulations: the possible role of habitat carrying capacity

As a key parameter in the management of fish populations, individual growth rate (GR) variations were examined in the European eel (Anguilla anguilla; > 150 mm) using extensive mark–recapture surveys in the lotic habitats of two small rivers of western France: the Frémur, supposed to be saturated, and at the same latitude, the Oir with densities fivefold lower than those of the Frémur. In both systems, generalised linear models were used to test whether spatiotemporal factors such as dominant habitat type or local density affect GR variability. In the presumed unsaturated system, the Oir, GR variability is mainly explained by a set of habitat suitability drivers (density, dominant habitat type). In the Frémur, GRs appear independent of differences in habitat density or productivity. Below saturation, an increase in density will decrease the GR through intraspecific competition. At saturation, intraspecific competition reaches such high levels that regardless of eel density and productivity, the resources available by individual are similar throughout the system. In these circumstances, the effect of density on growth was presumed undetectable. Despite these contrasted results, mean GRs observed in both catchments were closed (~20 mm·year^?1). This is an unexpected result as GR is expected to be higher in unsaturated systems. This similarity could be explained by the difference between the two systems in terms of: (i) sex ratio (the Frémur is dominated by male, whereas the female is dominant in the Oir), (ii) habitat type distribution or (iii) possible interspecific competition (important salmonid populations in the Oir).     

INTRA- AND INTEROBSERVER VARIABILITY OF ULTRASONOGRAPHIC MEASUREMENTS OF THE THYROID GLAND IN HEALTHY BEAGLES

The repeatability of ultrasonographic measurements of the canine thyroid gland was evaluated. The variability of three different parameters (the maximal length, width, and height) within observer, between observer and between dogs was assessed based on three different measurements made by each of three observers infive healthy beagle dogs. From the three parameters, the volume of the gland was estimated using a formula of a rotation ellipse. The height and the volume had the lowest intra- and interobserver variability, while measurements of the length had the biggest intra- and interobserver variability. The mean values, with their 90% confidence interval were: height = 0.53cm [0.33-0.73], length = 2.45cm [2.04-2.85], width = 0.62cm [0.46- 0.78], volume = 0.38 cm3 [0.20-0.55].     

Transmission by Olpidium brassicae of Mirafiori lettuce virus and Lettuce big-vein virus, and Their Roles in Lettuce Big-Vein Etiology

ABSTRACT Big-vein disease occurs on lettuce worldwide in temperate conditions; the causal agent has been presumed to be Lettuce big-vein virus (LBVV), genus Varicosavirus, vectored by the soilborne fungus Olpidium brassicae. Recently, the role of LBVV in the etiology of big-vein disease has been questioned because a second soilborne virus, Mirafiori lettuce virus (MiLV), genus Ophiovirus, has been found frequently in big-vein-affected lettuce. LBVV and MiLV, detectable and distinguishable by enzyme-linked immunosorbent assay using specific antisera, were tested for their ability to be transmitted from lettuce to lettuce by mechanical inoculation of sap extracts, or by zoospores of O. brassicae, and to cause big-vein disease. Both viruses were mechanically transmissible from lettuce to herbaceous hosts and to lettuce, but very erratically. LBVV was transmitted by O. brassicae but lettuce infected with only this virus never showed symptoms. MiLV was transmitted in the same manner, and lettuce infected with this virus alone consistently developed big-vein symptoms regardless of the presence or absence of LBVV. With repeated mechanical transmission, isolates of both viruses appeared to lose the ability to be vectored, and MiLV appeared to lose the ability to cause big-vein symptoms. The recovery of MiLV (Mendocino isolate, from Cali-fornia) from stored O. brassicae resting spores puts the earliest directly demonstrable existence of MiLV at 1990.     

Treatment of canine parvoviral enteritis with interferon-omega in a placebo-controlled challenge trial

Canine parvoviral enteritis continues to cause significant morbidity and mortality in dogs worldwide, and efficacious antiviral therapies are lacking. The present trial was aimed at evaluating the therapeutic efficacy of a recombinant feline interferon (type omega) preparation in the treatment of parvoviral enteritis in dogs. A double-blind, placebo-controlled challenge trial was performed in beagle pups (8-9 weeks); clinical signs, body weight, hematologic parameters, and mortality were monitored for a period of 14 days after challenge. Fourteen animals were inoculated with virulent canine parvovirus; 10 animals that developed clinical signs thereby meeting the inclusion criteria were admitted to the treatment phase in two randomly selected groups (placebo and IFN) of equal size. The IFN group received daily intravenous injections of rFeIFN-omega (2.5 MU/kg) for three consecutive days. The placebo group received daily injections of saline without IFN. Both groups of animals received individual supportive treatment consisting of adjusted diet and electrolyte solution.All five dogs in the placebo group developed fulminating enteritis with typical clinical signs and died within 10 days post-inoculation (or 6 days post-treatment). In the IFN-treated group, one animal died on day 2 after the treatment was started, whereas the other four dogs survived the challenge and gradually recovered. Our data confirm that the rFeIFN-omega can exert a significant therapeutic effect on dogs with parvoviral enteritis by improving clinical signs and reducing mortality.     

Prokinetic effects of erythromycin on the ileum, cecum, and pelvic flexure of horses during the postoperative period

OBJECTIVE: To evaluate the effect of erythromycin on motility of the ileum, cecum, and pelvic flexure of horses during the postoperative and post-recovery periods. ANIMALS: 8 healthy adult horses. PROCEDURE: Horses were anesthetized and bipolar electrodes were implanted in smooth muscle of the ileum, cecum, and pelvic flexure. Approximately 4, 16, and 24 hours (postoperative recording sessions) and at least 8 days (post-recovery recording session) after surgery, myoelectric activity was recorded before and after administration of erythromycin (0.5 mg/kg). RESULTS: Following erythromycin administration, myoelectric activity was increased in the ileum during all postoperative recording sessions but not during the post-recovery recording session. Myoelectric activity was increased in the cecum following erythromycin administration only during the post-recovery recording session. Myoelectric activity was increased in the pelvic flexure following erythromycin administration during all recording sessions. During several recording sessions, there were short periods during which myoelectric activity was significantly decreased following erythromycin administration. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that erythromycin has an effect on myoelectric activity of the ileum, cecum, and pelvic flexure in horses; however, prokinetic effects of erythromycin administered during the postoperative period were not always the same as effects obtained when the drug was administered after horses had recovered from the effects of surgical implantation of recording devices. Therefore, caution must be exercised when extrapolating results of prokinetic studies in healthy animals to animals with abnormal gastrointestinal tract motility.     

Abomasal displacement and volvulus in beef cattle: 19 cases (1988-1998)

OBJECTIVE: To assess signalment, history, results of clinical and laboratory testing, and outcome for beef cattle with a left displaced abomasum (LDA), right displaced abomasum (RDA), or abomasal volvulus (AV). DESIGN: Retrospective study. ANIMALS: 19 beef cattle with an AV, LDA, or RDA. PROCEDURE: Signalment; history; results of physical examination, diagnostic testing, and surgical exploration; and condition of the animal at discharge were obtained from medical records. RESULTS: Fourteen cattle had an AV, 4 had an RDA, and 1 had an LDA. Duration of clinical signs ranged from 1 to 21 days. Eighteen cattle had an AV or RDA; 7 were Brahmans, 12 were males, and median age was 10 months. Abdominal distention was observed in 11 cattle, heart rate of > or = 100 beats/minute was detected in 14, and the abomasum was palpable per rectum in all cattle in which per rectal examination was performed. Leukocytosis, neutrophilia, hyperglycemia, azotemia, hypochloremia, and hypokalemia were common laboratory findings. At surgery, 3 cattle with an AV or RDA had a ruptured abomasum. Of the remaining 15 cattle, 12 survived. CONCLUSIONS: Clinical course in beef cattle with an AV or RDA was more protracted than that typically associated with these conditions in dairy cattle, but survival rate in beef cattle that did not have rupture of the abomasum was similar to that of dairy cattle. CLINICAL RELEVANCE: Abomasal displacement should be considered for beef cattle with abdominal distention. Prognostic indicators recommended for use in dairy cattle may not be useful for beef cattle.