Foliar nematode,Litylenchus crenatae ssp. mccannii,population dynamics in leaves and buds of beech leaf disease‐affected trees in Canada and the US

A foliar nematode, Litylenchus crenatae ssp. mccannii, is associated with beech leaf disease (BLD) symptoms. Information about the types of tissues parasitized and how nematode populations fluctuate in these tissues over time is needed to improve surveys as well as understand the nematodes role in BLD. During this study, the nematode was detected throughout the known range of BLD by researchers at both Canadian and US institutions using a modified pan method to extract nematodes. Monthly collections of symptomatic and asymptomatic leaves during the growing season (May–October), and leaves and buds between growing seasons (November–March), revealed that nematodes were present in all tissue types. Progressively larger numbers of nematodes were detected in symptomatic leaves from Ohio and Ontario, with the greatest detections at the end of the growing season. Smaller numbers of nematodes were detected in asymptomatic leaves from BLD‐infected trees, typically at the end of the growing season. The nematode was detected overwintering in buds and detached leaves. The discovery of small numbers of nematodes in detached leaves at one location before BLD was detected indicates that nematodes may have been present before disease symptoms were expressed. Other nematodes, Plectus and Aphelenchoides spp., were infrequently detected in small numbers. Our findings support the involvement of the nematode in BLD and indicate that symptoms develop only when certain requirements, such as infection of buds, are met. We also found that the nematode can be reliably detected in buds and leaves using the modified pan extraction method.     

Effects of different dietary copper sources on the growth and intestinal microbial communities of Pacific white shrimp (Litopenaeus vannamei)

An 8‐week feeding trial was conducted to evaluate the effects of dietary copper sources on growth performance and intestinal microbial communities of juvenile Pacific white shrimp (Litopenaeus vannamei). Four isonitrogenous (420 g/kg crude protein) and isolipidic (70 g/kg crude lipid) experimental diets were formulated to contain different copper sources, Diet NSC (no‐supplemented copper), Diet CS (copper sulphate), Diet Availa (copper amino acid complex from Availa^®Cu100) and Diet M (1:1, copper sulphate + copper amino acid complex). A total of 360 Pacific white shrimp juveniles (initial weight: 1.86 ± 0.03 g) were randomly allocated into four groups, with three replicates per group and 30 shrimps each replicate. An Illumina‐based sequencing method was used to analyse the intestinal bacterial composition of shrimp juveniles. The results revealed that shrimps fed Diet M had significantly higher percent weight gain (PWG) than that fed Diet NSC and Diet CS, while there were no significant differences between Diet M and Diet Availa. Survival was not affected by the dietary copper sources. Proteobacteria and Bacteroidetes were dominant in the intestines of Pacific white shrimp. Shrimps fed Diet M and Diet Availa had higher bacterial richness and diversity than those fed Diet NSC and Diet CS with no significant differences among all treatments. Furthermore, Diet M and Diet Availa which contained copper amino acid complex reduced the relative abundance of Vibrionaceae in shrimp intestinal tract. This study indicated that dietary copper sources could affect the intestinal microbial communities and diets supplemented with Availa^®Cu100 could have a positive impact on the growth performance and decrease the potential risk of disease in Pacific white shrimp.     

Computed tomography of testicular torsion in a juvenile dog with unilateral cryptorchidism

A 14-week-old male unilaterally cryptorchid Clumber spaniel was presented for acute lethargy. Physical examination revealed abdominal pain, and a single testis was palpated in the scrotum. Abdominal ultrasound and computed tomography (CT) revealed a poorly vascularized, ovoid structure immediately caudal to the left kidney with scant regional peritoneal effusion. Left intra-abdominal testicular torsion was confirmed at surgery, and routine cryptorchidectomy was performed. The patient recovered uneventfully from anesthesia and surgery.Key clinical message:The most common CT characteristics of testicular torsion were present in this case and correlated well with sonographic findings to allow for rapid, accurate diagnosis and surgical planning of unilateral, non-neoplastic, intra-abdominal cryptorchid testicular torsion in a juvenile dog. Contrast enhanced CT facilitated accurate localization of the undescended testis and evaluation of testicular perfusion and may be a useful alternative to ultrasound for diagnosing testicular torsion, especially in indeterminate cases.     

PUNCTURE WOUNDS INTO THE NAVICULAR BURSA OF THE HORSE

Radiography was used to evaluate 32 horses presented for puncture wounds into the navicular bursa. At the initial radiographic examination, 21 horses had no radiographic signs of osteomyelitis, while 11 did. The mean-time interval between injury and radiographic examination was 20.6 days for horses without evidence of osteomyelitis and 59.3 days for those with evidence of osteomyelitis. Radiographic signs of osteomyelitis of the navicular bone included flexor cortical destruction and irregularity of the flexor surface. Other abnormalities included pathologic fracture of the navicular bone, subluxation of the distal interphalangeal joint, or secondary joint disease. The lateromedial and palmaroproximal-palmarodistal oblique projections were most useful for identifying abnormalities of the navicular bone. There was a high correlation between horses that had positive presurgical radiographic signs and surgical findings. However, approximately 50% of horses that had negative radiographic findings initially had positive surgical findings. Ten of 21 horses with negative radiographic findings on initial examination had evidence of bony lesions when reevaluated from 3 weeks to 6 years later. Nine of 11 horses with radiographic signs of osteomyelitis on initial radiographic examination were euthanatized or had an unsatisfactory outcome. Seven of 10 horses with radiographic signs on reexamination were euthanatized. Thirteen of 20 horses with positive surgical findings for navicular bone infection were euthanatized or had an unsatisfactory outcome.     

The Economics Associated with Crawfish Production from Louisiana's Atchafalaya Basin 1

Unpredictable water levels for the Atchafalaya River resulting from man's efforts to prevent flooding in South Louisiana lead to an unstable market for Louisiana's annual crawfish production. Empirical models presented show that yields from the basin can be estimated on a monthly basis using bimonthly changes in water level, unemployment rates, and crawfish harvests from ponds. The monthly demand model for basin crawfish yielded a price flexibility of –0.059 and a corresponding price elasticity of –16.94. These empirical results support hypotheses that substitutes for crawfish are available to consumers. Uncertain yields from the basin due to the sort of water level fluctuations documented in this study suggest that investment in this area of the Louisiana crawfish industry will continue to be hampered.     

Survey of academic veterinarians' clinical practice in cardiopulmonary–cerebral resuscitation

Objective: To document the clinical practice of cardiopulmonary–cerebral resuscitation (CPCR) among academic veterinarians. Design: Survey. Setting: Eight colleges of veterinary medicine in the United States. Subjects: Two hundred and one academic veterinarians. Interventions: The survey was distributed by hand by the authors into the mailboxes of small animal faculty, residents, and interns. Demographic variables, questions regarding number of cardiopulmonary arrests (CPA) supervised and number successful, do not attempt resuscitation discussions, and Likert‐style questions about client presence during CPCR, appropriateness of CPCR, and CPCR decision‐making were included. Multiple linear regression models were constructed to determine the effect of multiple questions on different target variables of interest. Measurements and main results: Numerous differences were noted based on institution, gender, specialty, and position. Most institutions did not have a standard resuscitation consent form. Most respondents believed the client, house officer, and senior clinician should determine whether to perform resuscitation or not. Quality of life was the most significant determinant of whether to resuscitate or not, followed by long‐term prognosis, then short‐term prognosis. Conclusions: Veterinarians differ in many aspects of their approach to CPA and resuscitation. Creating consensus within the veterinary profession would benefit client service and patient care.     

Horse Activity is Associated with Degraded Subalpine Grassland Structure and Reduced Habitat for a Threatened Rodent

Feral (wild) horses present significant challenges for landscape managers. A major effect of horses is trampling, which erodes soil and alters vegetation cover, which is often critical habitat for threatened animals. We examined the direct and indirect impacts of horses, kangaroos, and rabbits on the broad-toothed rat (Mastacomys fuscus), a threatened rodent in subalpine grasslands in Kosciusko National Park, which contains a large wild horse population. Our objective was to examine the relationship between the activity of different herbivores and 1) structural attributes of the vegetation (cover and density of different plant groups) and 2) length of broad-toothed rat runways and the presence of scat along these runways as proxies of broad-toothed rat activity. We assessed herbivore activity and measured vegetation cover, structure, and richness and total length of runways used by broad-toothed rats as a measure of activity. We used structural equation modeling to test the hypothesis that horse activity would lead to reductions in rat habitat directly, by increasing disturbance, and indirectly, by altering vegetation structure. Quadrats showing no evidence of horse activity had longer broad-toothed rat runways, taller but fewer grasses, double the shrub cover, and lower plant richness than quadrats showing evidence of horse activity. Structural equation modeling showed that there were no significant direct associations between horse activity and rat activity. However, increasing horse activity was associated with an indirect negative effect on broad-toothed rat activity by suppressing the positive relationship between grass height and rat activity. There were no significant effects of rabbits on any environmental variables, and kangaroo grazing was associated with an increase in shrub cover only. Disturbance by horses likely alters vegetation structure, by reducing grass height, making it less suitable for broad-toothed rats, thereby reducing their populations. Horses should be restricted from accessing critical broad-toothed rat habitat.