Antimicrobial substances and chick growth promotion: The growth‐promoting activities of antimicrobial substances,including fifty‐two used either in therapy or as dietary additives

1. Fifty‐five antimicrobial substances were tested for their ability to promote growth when added to the diet of chicks.

2. Both cephalosporins and all the nine penicillins tested were active.

3. Of six aminoglycosides, streptomycin and gentamicin had the greatest activity and neomycin had none.

4. Growth rate was significantly improved by clindamycin, lincomycin, vancomycin, spectinomycin, rifampicin, oxytetracycline, chlortetracycline, erythromycin, tylosin, flavomycin, virginiamycin and zinc bacitracin. Chloramphenicol and nalidixic acid were inactive. Polymixin B, novo‐biocin, cycloserine, phosphonomycin, and sodium fusidate had little activity. Fusidic acid promoted growth at 250 mg/kg diet.

5. Trimethoprim was inactive alone and in combination with sulpha‐diazine. Of seven 5‐nitroimidazoles, only dimetridazole and metronidazole showed slight activity. Of the six 5‐nitrofurans, only nitrovin, the standard reference substance used, promoted growth.

6. Caprylohydroxamic acid, a urease inhibitor, had no beneficial effect on growth rate or on the efficiency of food conversion.

7. The growth‐promoting properties of the various substances could not be related with their known antimicrobial and absorption characteristics in mammals.     

The urbanization of wildlife management: Social science, conflict, and decision making

Increasing urbanization of rural landscapes has created new challenges for wildlife management. In addition to changes in the physical landscape, urbanization has also produced changes in the socio-cultural landscape. The greater distancing from direct interaction with wildlife in urbanized societies has led to the emergence of a culture whose meanings for wildlife are less grounded in the utilitarian/instrumental orientation of rural agrarian systems. Urban perspectives on wildlife are comprised of more highly individualized emotional/symbolic values. This shift creates two problems with respect to managing wildlife in an urbanizing landscape. First the increased diversity in values and meanings increases the likelihood for social conflicts regarding wildlife management while at the same time making socially acceptable resolutions more intractable. This in turn requires fundamental changes in decision-making paradigms and the research approaches used to inform decision making. Second, as remaining rural communities feel the pressures of urbanization, wildlife conflicts become conflicts not just over wildlife but conflict over larger socio-political concepts such as equity, tradition, private property rights, government control, power, and acceptable forms of knowledge. This paper examines the wildlife management implications of changes associated with increasing urbanization and employs two case studies to illustrate these issues. First a study of a controversy over urban deer management provides insights into how to map conflicting values and search for common ground in an urban culture with increasingly individualistic values for wildlife. Specifically, the analysis illustrates that common ground may, at times, be found even among people with conflicting value systems. The second case study examined a ranching community faced with predator reintroduction. This case study illustrates tensions that occur when the community of interest (i.e. a national public) is broader than the community of place in which the problem occurs. In this latter situation, the debate centers around more than just different views about the rights of animals. It also entailed the rights of individuals and communities to decide their future. The conclusion discusses the need for wildlife institutions to adapt their underlying decision making philosophy including the way science is integrated into decision making processes in light of the changes in social context caused by urbanization.     

Single and multiple dose pharmacokinetics of a novel mirtazapine transdermal ointment in cats

Single and multiple dose pharmacokinetics (PK) of mirtazapine transdermal ointment applied to the inner ear pinna of cats were assessed. Study 1 was a randomized, cross‐over single dose study (n = 8). Cats were treated once with 0.5 mg/kg of mirtazapine transdermal ointment applied topically to the inner ear pinna (treatment) or administered orally (control) and then crossed over after washout. Plasma was collected predose and at specified intervals over 96 hr following dosing. Study 2 was a multiple dose study (n = 8). Cats were treated daily for 14 days with 0.5 mg/kg of mirtazapine transdermal ointment applied topically to the inner pinna. Plasma was collected on Day 13 predose and at specified intervals over 96 hr following the final dose. In Study 1, single transdermal administration of mirtazapine resulted in mean T_max = 15.9 hr, C_max = 21.5 ng/mL, AUC_0‐24 = 100 ng*hr/mL, AUC_0‐∞ = 260 ng*hr/mL and calculated half‐life = 26.8 hr. Single oral administration of mirtazapine resulted in mean T_max = 1.1 hr, C_max = 83.1 ng/mL, AUC_0‐24 = 377 ng*hr/mL, AUC_0‐∞ = 434 ng*hr/mL and calculated half‐life = 10.1 hr. Mean relative bioavailability (F) of transdermal to oral dosing was 64.9%. In Study 2, daily application of mirtazapine for 14 days resulted in mean T_max = 2.1 hr, C_max = 39.6 ng/mL, AUC_0‐24 = 400 ng*hr/mL, AUC_0‐∞ = 647 ng*hr/mL and calculated half‐life = 20.7 hr. Single and repeat topical doses of a novel mirtazapine transdermal ointment achieve measurable plasma concentrations in cats.     

Grassland songbird occurrence on remnant prairie patches is primarily determined by landscape characteristics

Context

North American grassland songbird populations have declined significantly due to habitat loss and fragmentation. Understanding the influence of the surrounding landscape on prairie fragment occupancy is vital for predicting the fate of grassland birds in these heavily altered landscapes.

Objectives

We examined the relative importance of local and landscape variables on grassland bird occupancy of prairie fragments using a focal-patch study. We also investigated the spatial scale at which landscape variables were most influential.

Methods

We surveyed birds on 29 unplowed prairie fragments in western Minnesota and eastern North and South Dakota. We quantified local habitat on the fragment using vegetation surveys and aerial photographs and the landscape surrounding the fragment out to 4 km using aerial photographs. We analyzed occupancy using multi-model approaches applied to multiple logistic regression.

Results

Of 38 species encountered, nine were neither too rare nor too abundant to be analyzed. Predictors of patch occupancy were unique for each bird species, yet general patterns emerged. For eight species, landscape variables were more important than local variables. Mostly, those landscape variables measured configuration (e.g., edge density) and not composition (e.g., percent cover of a particular matrix element). Landscape effects were mostly from variables measured at the greatest extents from the prairie fragment.

Conclusions

Using a focal-patch study design we demonstrated the importance of the surrounding landscape, often out to 4 km from the fragment edge, on prairie occupancy by grassland birds. Effective management of grassland songbirds will require attention to the landscape context of prairie fragments.

     

Linking mesoscale landscape heterogeneity and biodiversity: gardens and tree cover significantly modify flower-visiting beetle communities

Landscape Ecology - Maintaining biodiversity in multifunction landscapes is a significant challenge. Planning for the impacts of change requires knowledge of how species respond to landscape...     

Systemic Listeria monocytogenes infection and concurrent pleural mesothelioma in a cat

Herein we describe a rare case of systemic Listeria monocytogenes infection with concurrent pleural mesothelioma in a stray cat that was found dead and submitted for autopsy. Gross pathology changes consisted of thoracic clear yellow fluid admixed with suspended fibrin strands; clear-to-tan, variably sized, <3 mm diameter pulmonary nodules; and enlargement of the submandibular, retropharyngeal, and prescapular lymph nodes. Histologic changes consisted of extensive areas of suppurative inflammation and necrosis with mineralization that partially effaced the pulmonary parenchyma and lymph nodes. Random, distinct necrotic foci were present throughout the hepatic parenchyma. Extending from the pleura, within perinecrotic alveolar spaces, and infiltrating the submandibular, retropharyngeal, and prescapular lymph nodes were dense sheets of neoplastic epithelioid cells with moderate pleomorphism and occasional karyomegaly and multinucleation. Neoplastic cells exhibited immunolabeling for pancytokeratin AE1/AE3 and vimentin, consistent with pleural mesothelioma. Aerobic bacterial culture of lung yielded heavy growth of L. monocytogenes. Immunohistochemistry (IHC) for L. monocytogenes revealed clusters of bacteria in the lung, lymph node, and liver. Pathologic changes were consistent with systemic listeriosis, confirmed by bacterial culture and IHC, and concurrent pleural mesothelioma.     

INVITED REVIEW—IMAGE REGISTRATION IN VETERINARY RADIATION ONCOLOGY: INDICATIONS,IMPLICATIONS, AND FUTURE ADVANCES

The field of veterinary radiation therapy (RT) has gained substantial momentum in recent decades with significant advances in conformal treatment planning, image‐guided radiation therapy (IGRT), and intensity‐modulated (IMRT) techniques. At the root of these advancements lie improvements in tumor imaging, image alignment (registration), target volume delineation, and identification of critical structures. Image registration has been widely used to combine information from multimodality images such as computerized tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET) to improve the accuracy of radiation delivery and reliably identify tumor‐bearing areas. Many different techniques have been applied in image registration. This review provides an overview of medical image registration in RT and its applications in veterinary oncology. A summary of the most commonly used approaches in human and veterinary medicine is presented along with their current use in IGRT and adaptive radiation therapy (ART). It is important to realize that registration does not guarantee that target volumes, such as the gross tumor volume (GTV), are correctly identified on the image being registered, as limitations unique to registration algorithms exist. Research involving novel registration frameworks for automatic segmentation of tumor volumes is ongoing and comparative oncology programs offer a unique opportunity to test the efficacy of proposed algorithms.