Intragenic MFSD8 duplication and histopathological findings in a rabbit with neuronal ceroid lipofuscinosis.

Neuronal ceroid lipofuscinoses (NCL) are among the most prevalent neurodegenerative disorders of early life in humans. Disease-causing variants have been described for 13 different NCL genes. In this study, a refined pathological characterization of a female rabbit with progressive neurological signs reminiscent of NCL was performed. Cytoplasmic pigment present in neurons was weakly positive with Sudan black B and autofluorescent. Immunohistology revealed astrogliosis, microgliosis and axonal degeneration. During the subsequent genetic investigation, the genome of the affected rabbit was sequenced and examined for private variants in NCL candidate genes. The analysis revealed a homozygous ~10.7 kb genomic duplication on chromosome 15 comprising parts of the MFSD8 gene, NC_013683.1:g.103,727,963_103,738,667dup. The duplication harbors two internal protein coding exons and is predicted to introduce a premature stop codon into the transcript, truncating ~50% of the wild-type MFSD8 open reading frame encoding the major facilitator superfamily domain containing protein 8, XP_002717309.2:p.(Glu235Leufs*23). Biallelic loss-of-function variants in MFSD8 have been described to cause NCL7 in human patients, dogs and a single cat. The available clinical and pathological data, together with current knowledge about MFSD8 variants and their functional impact in other species, point to the MFSD8 duplication as a likely causative defect for the observed phenotype in the affected rabbit.

WILDbase: towards a common database to improve wildlife disease surveillance in Europe.

BackgroundTo be better prepared for emerging wildlife-borne zoonoses, we need to strengthen wildlife disease surveillance.AimThe aim of this study was to create a topical overview of zoonotic pathogens in wildlife species to identify knowledge gaps and opportunities for improvement of wildlife disease surveillance.MethodsWe created a database, which is based on a systematic literature review in Embase focused on zoonotic pathogens in 10 common urban wildlife mammals in Europe, namely brown rats, house mice, wood mice, common voles, red squirrels, European rabbits, European hedgehogs, European moles, stone martens and red foxes. In total, we retrieved 6,305 unique articles of which 882 were included.ResultsIn total, 186 zoonotic pathogen species were described, including 90 bacteria, 42 helminths, 19 protozoa, 22 viruses and 15 fungi. Most of these pathogens were only studied in one single animal species. Even considering that some pathogens are relatively species-specific, many European countries have no (accessible) data on zoonotic pathogens in these relevant animal species. We used the Netherlands as an example to show how this database can be used by other countries to identify wildlife disease surveillance gaps on a national level. Only 4% of all potential host-pathogen combinations have been studied in the Netherlands.ConclusionsThis database comprises a comprehensive overview that can guide future research on wildlife-borne zoonotic diseases both on a European and national scale. Sharing and expanding this database provides a solid starting point for future European-wide collaborations to improve wildlife disease surveillance.

Determination of intraocular pressure and Schirmer tear test and the comparison between the applanation tonometer (Tono-Pen AVIA®) and the rebound tonometer (TonoVet Plus®) in mini lionhead rabbits.

OBJECTIVE: To determine intraocular pressure (IOP) and tear production, as well as to compare the IOP obtained with the TonoVet Plus® (rebound) with the Tono-Pen Avia® (applanation) tonometers. ANIMALS: Twenty-five Mini Lionhead rabbits (n = 50 eyes). PROCEDURE: Tear production was measured at 6:00 a.m. and 6:00 p.m. by using the STT. The IOP reading was performed with the rebound tonometer, followed by the applanation tonometer, at 6:00 a.m., 9:00 a.m., 12:00 p.m., 3:00 p.m., and 6:00 p.m. Regression analysis, analysis of variance (anova) and Bland-Altman statistics were used. RESULTS: Daily tear production was 10.25 ± 3.75 mm/min, with no differences among the moments evaluated. Average daily IOP was 17.7 ± 3.08 mmHg with the TonoVet Plus® and 11.5 ± 4.56 mmHg with the Tono-Pen Avia®. IOP values were higher at the beginning and end of the day with both tonometers. CONCLUSION: The IOP values are higher with the TonoVet Plus® tonometer. The reference values of IOP and tear production obtained in this work may support the diagnosis, treatment, and monitoring of ocular disorders in pet Mini Lionhead rabbits.

Genome-wide association studies for diarrhoea outcomes identified genomic regions affecting resistance to a severe enteropathy in suckling rabbits.

Selection and breeding strategies to improve resistance to enteropathies are essential to reaching the sustainability of the rabbit production systems. However, disease heterogeneity (having only as major visible symptom diarrhoea) and low disease heritability are two barriers for the implementation of these strategies. Diarrhoea condition can affect rabbits at different life stages, starting from the suckling period, with large negative economic impacts. In this study, from a commercial population of suckling rabbits (derived from 133 litters) that experienced an outbreak of enteropathy, we first selected a few animals that died with severe symptoms of diarrhoea and characterized their microbiota, using 16S rRNA gene sequencing data. Clostridium genus was consistently present in all affected specimens. In addition, with the aim to identify genetic markers in the rabbit genome that could be used as selection tools, we performed genome-wide association studies for symptoms of diarrhoea in the same commercial rabbit population. These studies were also complemented with FST analyses between the same groups of rabbits. A total of 332 suckling rabbits (151 with severe symptoms of diarrhoea, 42 with mild symptoms and 129 without any symptoms till the weaning period), derived from 45 different litters (a subset of the 133 litters) were genotyped with the Affymetrix Axiom OrcunSNP Array. In both genomic approaches, rabbits within litters were paired to constitute two groups (susceptible and resistant, including the mildly affected in one or the other group) and run case and control genome-wide association analyses. Genomic heritability estimated in the designed experimental structure integrated in a commercial breeding scheme was 0.19-0.21 (s.e. 0.09-0.10). A total of eight genomic regions on rabbit chromosome 2 (OCU2), OCU3, OCU7, OCU12, OCU13, OCU16 and in an unassembled scaffold had significant single nucleotide polymorphisms (SNPs) and/or markers that trespassed the FST percentile distribution. Among these regions, three main peaks of SNPs were identified on OCU12, OCU13 and OCU16. The QTL region on OCU13 encompasses several genes that encode members of a family of immunoglobulin Fc receptors (FCER1G, FCRLA, FCRLB and FCGR2A) involved in the immune innate system, which might be important candidate genes for this pathogenic condition. The results obtained in this study demonstrated that resistance to an enteropathy occurring in suckling rabbits is in part genetically determined and can be dissected at the genomic level, providing DNA markers that could be used in breeding programmes to increase resistance to enteropathies in meat rabbits.

Psoroptes cuniculi infestation in pet rabbits in Tabasco, Mexico, 2021-2022.

BACKGROUND: Rabbits are an important worldwide meat- and fibre-producing animal, and they are popular pets. The rabbit ear mite, Psoroptes cuniculi, causes severe dermatological disease. Epidemiological data on P. cuniculi infestations are important for public health. OBJECTIVE: The objective of the study was to determine the frequency of P. cuniculi infestation in pet rabbits and evaluate epidemiological factors associated with infestation. ANIMALS: Two hundred pet rabbits presented for veterinary care between 2021 and 2022. MATERIALS AND METHODS: Physical examination, otoscopy and microscopy were used for ear mite identification. Association with age, sex, body mass index (BMI), breed, feeding and housing management was analysed. RESULTS: Of the 200 rabbits, 59 (29.5%) were positive for P. cuniculi. Only female sex had a positive association with P. cuniculi. CONCLUSIONS AND CLINICAL SIGNIFICANCE: Psoroptes cuniculi in pet rabbits has a similar frequency to that reported in meat-producing rabbits, and female sex had a positive association.

Hepatobiliary organoids derived from leporids support the replication of hepatotropic lagoviruses.

The genus Lagovirus of the family Caliciviridae contains some of the most virulent vertebrate viruses known. Lagoviruses infect leporids, such as rabbits, hares and cottontails. Highly pathogenic viruses such as Rabbit haemorrhagic disease virus 1 (RHDV1) cause a fulminant hepatitis that typically leads to disseminated intravascular coagulation within 24-72 h of infection, killing over 95 % of susceptible animals. Research into the pathophysiological mechanisms that are responsible for this extreme phenotype has been hampered by the lack of a reliable culture system. Here, we report on a new ex vivo model for the cultivation of lagoviruses in cells derived from the European rabbit (Oryctolagus cuniculus) and European brown hare (Lepus europaeus). We show that three different lagoviruses, RHDV1, RHDV2 and RHDVa-K5, replicate in monolayer cultures derived from rabbit hepatobiliary organoids, but not in monolayer cultures derived from cat (Felis catus) or mouse (Mus musculus) organoids. Virus multiplication was demonstrated by (i) an increase in viral RNA levels, (ii) the accumulation of dsRNA viral replication intermediates and (iii) the expression of viral structural and non-structural proteins. The establishment of an organoid culture system for lagoviruses will facilitate studies with considerable implications for the conservation of endangered leporid species in Europe and North America, and the biocontrol of overabundant rabbit populations in Australia and New Zealand.

Quantifying resistance to myxomatosis in wild rabbits produces novel evolutionary insights.

Wild rabbits in Australia developed genetic resistance to the myxoma virus, which was introduced as a biological control agent. However, little is known about the rate at which this evolutionary change occurred. We collated data from challenge trials that estimated rabbit resistance to myxomatosis in Australia and expressed resistance on a continuous scale, enabling trends in its development to be assessed over 45 years up to 1995. Resistance initially increased rapidly, followed by a plateau lasting ten years, before a second rapid increase occurred associated with the introduction of European rabbit fleas as myxoma virus vectors. By contrast, in the United Kingdom, where rabbit flea vectors were already present when the myxoma virus initially spread, resistance developed more slowly. No estimates of rabbit resistance to myxomatosis have been made for almost 30 years, despite other highly lethal rabbit pathogens becoming established worldwide. Continued testing of wild-caught rabbits in Australia to determine current levels of resistance to myxomatosis is recommended to assess its current effectiveness for managing pest rabbits. Given the economic and environmental significance of invasive rabbits, it would be remiss to manage such biological resources and ecosystem services poorly.

Mammary gland inflammation in rabbits does (Oryctolagus cuniculus): A systematic review.

Mastitis is a common condition in rabbit (Oryctolagus cuniculus) does, especially in rabbitries where mammae inflammations are the leading pathological expression of Staphylococcus aureus infections in reproductive females. It affects both the litter and the lactating female, including subsequent lactations. Non-septic (i.e. galactostasis and cystic mastitis) and septic (i.e. Mastitis acuta; including Mastitis gangrenosa; and Mastitis chronica) mammary inflammations are acknowledged; however, the literature is scarce regarding non-septic inflammations or subclinical mastitis. Thus, the present systematic review highlights and summarizes the existing data concerning mastitis in rabbit does, including diagnosis and treatment plans.

Population genomic structures and signatures of selection define the genetic uniqueness of several fancy and meat rabbit breeds.

Following the recent domestication process of the European rabbit (Oryctolagus cuniculus), many different breeds and lines, distinguished primarily by exterior traits such as coat colour, fur structure and body size and shape, have been constituted. In this study, we genotyped, with a high-density single-nucleotide polymorphism panel, a total of 645 rabbits from 10 fancy breeds (Belgian Hare, Champagne d'Argent, Checkered Giant, Coloured Dwarf, Dwarf Lop, Ermine, Giant Grey, Giant White, Rex and Rhinelander) and three meat breeds (Italian White, Italian Spotted and Italian Silver). ADMIXTURE analysis indicated that breeds with similar phenotypic traits (e.g. coat colour and body size) shared common ancestries. Signatures of selection using two haplotype-based approaches (iHS and XP-EHH), combined with the results obtained with other methods previously reported that we applied to the same breeds, we identified a total of 5079 independent genomic regions with some signatures of selection, covering about 1777 Mb of the rabbit genome. These regions consistently encompassed many genes involved in pigmentation processes (ASIP, EDNRA, EDNRB, KIT, KITLG, MITF, OCA2, TYR and TYRP1), coat structure (LIPH) and body size, including two major genes (LCORL and HMGA2) among many others. This study revealed novel genomic regions under signatures of selection and further demonstrated that population structures and signatures of selection, left into the genome of these rabbit breeds, may contribute to understanding the genetic events that led to their constitution and the complex genetic mechanisms determining the broad phenotypic variability present in these untapped rabbit genetic resources.

Examination of the pharmacokinetics and differential inhibition of cyclooxygenase isoenzymes in New Zealand white rabbits (Oryctolagus cuniculus) by the Non-Steroidal anti-inflammatory Robenacoxib.

Effective rabbit analgesia is challenging, and there are few studies available on the newer COX-2 selective NSAIDs, such as robenacoxib. This study aimed to establish the pharmacokinetics of oral and subcutaneous robenacoxib, describe its inhibitory actions on COX enzymes, and develop dosing, using six healthy New Zealand white rabbits. Pharmacokinetics were determined from plasma concentrations after oral administration of robenacoxib (0.83-0.96 mg/kg) and also after subcutaneous administration (2 mg/kg). The inhibitory actions of robenacoxib were evaluated by measuring plasma concentrations of thromboxane B2 (TBX2 ) and prostaglandin E2 (PGE2 ) as surrogate markers of cyclooxygenase enzyme isoform inhibition. The mean maximum concentration for oral and subcutaneous administration was 0.23 µg/ml and 5.82 µg/ml, respectively. Oral robenacoxib administration did not demonstrate a significant difference between any time point for PGE2 or TBX2 , though subcutaneous administration did for both. There was no significant difference in PGE2 or TBX2 concentrations at any time point when comparing subcutaneous versus oral routes. Although the results support that plasma robenacoxib exceeds the therapeutic levels compared to dogs and cats, there was little significance in the difference in the changes associated with COX-1 and COX-2 inhibition. Further studies are warranted to determine appropriate dosing, safety, and efficacy in rabbits.

Rice gluten meal as a substitute for soybean meal in the diets for growing rabbits.

The impacts of different dietary levels of rice gluten meal (RGM) on growth performance, digestibility, carcass characteristics, and blood traits of growing New Zealand White (NZW) rabbits were studied. One hundred and twenty, 6 weeks old weaned male rabbits (body weight; 682 [g] ± 23) were randomly allotted into four groups. The control diet contained 160 [g/kg] soybean meal (SBM), while the other three diets were obtained by replacing 40, 80, and 120 [g/kg] SBM with RGM (RGM40, RGM80, and RGM120, respectively). The results showed that RGM contained higher levels of dry matter (DM), crude protein (CP), ether extract (EE), ash, and gross energy than SBM. RGM contained a high level of arginine followed by leucine and valine as essential amino acids and high levels of glutamic, aspartic acid, and alanine as non-essential amino acids. The obtained results showed that the final body weight of rabbits fed diets containing 40, 80, and 120 [g/kg] RGM was higher than those fed the control diet. The daily weight gain of rabbits fed RGM diets increased (p < 0.05) by 10.50%, 6.50%, and 10.00%, respectively, compared to the control group. Rabbits fed RGM80 showed the highest (p < 0.05) digestibility of DM, organic matter (OM), EE, neutral detergent fibre (NDF), and acid detergent fibre (ADF) compared to the other tested levels. Rabbits fed RGM120 had the highest (p < 0.05) digestible energy (DE) and digestible crude protein (DCP) values. RGM inclusion levels of 40 and 80 [g/kg] increased (p < 0.05) plasma total protein and albumin compared to the control group. Rabbits fed a diet containing RGM40 had the highest (p < 0.05) globulin level. The highest (p < 0.05) plasma urea concentration level was measured in the rabbit group fed the RGM120 diet. Conclusively, RGM could be a valuable ingredient for growing rabbits, as at all the tested levels improved growth performance, digestibility, and nutritional values.

Cranial shape variation in domestication: A pilot study on the case of rabbits.

Domestication leads to phenotypic characteristics that have been described to be similar across species. However, this "domestication syndrome" has been subject to debate, related to a lack of evidence for certain characteristics in many species. Here we review diverse literature and provide new data on cranial shape changes due to domestication in the European rabbit (Oryctolagus cuniculus) as a preliminary case study, thus contributing novel evidence to the debate. We quantified cranial shape of 30 wild and domestic rabbits using micro-computed tomography scans and three-dimensional geometric morphometrics. The goal was to test (1) if the domesticates exhibit shorter and broader snouts, smaller teeth, and smaller braincases than their wild counterparts; (2) to what extent allometric scaling is responsible for cranial shape variation; (3) if there is evidence for more variation in the neural crest-derived parts of the cranium compared with those derived of the mesoderm, in accordance with the "neural crest hypothesis." Our own data are consistent with older literature records, suggesting that although there is evidence for some cranial characteristics of the "domestication syndrome" in rabbits, facial length is not reduced. In accordance with the "neural crest hypothesis," we found more shape variation in neural crest versus mesoderm-derived parts of the cranium. Within the domestic group, allometric scaling relationships of the snout, the braincase, and the teeth shed new light on ubiquitous patterns among related taxa. This study-albeit preliminary due to the limited sample size-adds to the growing evidence concerning nonuniform patterns associated with domestication.

Comparative analysis of genomic inbreeding parameters and runs of homozygosity islands in several fancy and meat rabbit breeds.

Runs of homozygosity (ROH) are defined as long stretches of DNA homozygous at each polymorphic position. The proportion of genome covered by ROH and their length are indicators of the level and origin of inbreeding. In this study, we analysed SNP chip datasets (obtained using the Axiom OrcunSNP Array) of a total of 702 rabbits from 12 fancy breeds and four meat breeds to identify ROH with different approaches and calculate several genomic inbreeding parameters. The highest average number of ROH per animal was detected in Belgian Hare (~150) and the lowest in Italian Silver (~106). The average length of ROH ranged from 4.001 ± 0.556 Mb in Italian White to 6.268 ± 1.355 Mb in Ermine. The same two breeds had the lowest (427.9 ± 86.4 Mb, Italian White) and the highest (921.3 ± 179.8 Mb, Ermine) average values of the sum of all ROH segments. More fancy breeds had a higher level of genomic inbreeding (as defined by ROH) than meat breeds. Several ROH islands contain genes involved in body size, body length, pigmentation processes, carcass traits, growth, and reproduction traits (e.g.: AOX1, GPX5, IFRD1, ITGB8, NELL1, NR3C1, OCA2, TRIB1, TRIB2). Genomic inbreeding parameters can be useful to overcome the lack of information in the management of rabbit genetic resources. ROH provided information to understand, to some extent, the genetic history of rabbit breeds and to identify signatures of selection in the rabbit genome.

Roles for GADD45 in Development and Cancer.

The Growth Arrest and DNA Damage-inducible 45 (GADD45) family of proteins are critical stress sensors that mediate various cellular responses, including DNA repair, cell cycle arrest, and apoptosis. Here, we review current literature investigating GADD45 family members as they relate to normal development and carcinogenesis. We first describe how modulation of GADD45 in model organisms has facilitated our understanding of roles for GADD45 family members in development and homeostasis. We then review current literature exploring roles for GADD45 in human cancer, describing cancer-associated alterations in expression of GADD45 family members; tumor suppressive and tumor promoting functions attributed to GADD5; and roles for GADD45 in cancer therapy. In exploring roles for GADD45 in development, homeostasis, and carcinogenesis, we aim to provide an informational resource that both highlighst current knowledge on this topic while also noting key gaps in our understanding of the biology of GADD45 that may be filled in order to best guide the development of novel approaches to improve diagnosis, monitoring, and therapy of human malignancies.

Effects of pomegranate peel and olive pomace supplementation on reproduction and oxidative status of rabbit doe.

The current study aimed to investigate the effects of pomegranate peel and olive pomace supplementation on the reproductive hormones, antioxidative status, reproductive capacity and maternal behaviour of rabbit does. Forty does were used for the experiments. The animals were randomly assigned to four groups of ten does. One group was fed on the control diet and was considered the control group (C). The second group was supplemented with 4.5% pomegranate peel in their diet (P), the third group was supplemented with 10% olive pomace in their diet (O), and the fourth group was supplemented with a mixture of pomegranate peel and olive pomace (PO). Compared with the control does, group P showed significantly increased serum levels of gonadotropic hormones and oestradiol-17ß two hours after mating, on the 20th day of lactation and after weaning; significantly increased progesterone levels at mid-pregnancy; and significantly increased in prolactin levels on the 10th day of lactation. Additionally, the results revealed significant increases in total DNA, protein concentration, litter size, milk yield and nest traits of groups P and PO. In conclusion, pomegranate peel supplementation improves the reproductive performance of does and increases their antioxidant parameters.

Autologous adipose-derived mesenchymal stem cells and hydroxyapatite for bone defect in rabbits.

This study aims to evaluate the effect of autologous adipose-derived mesenchymal stem cells (AAD-MSC), with and without synthetic absorbable hydroxyapatite (HAP-91), on the bone regeneration in rabbits. Thirty-four female white New Zealand rabbits were submitted to a 10 mm distal diaphyseal radius ostectomy, divided into 3 experimental groups according to the treatment established. The bone gap was filled with 0.15 ml of a 0.9% saline solution containing two million AAD-MSC (G1), or AAD-MSC associated with HAP-91 (G2). The control group (CG) received only 0.15 ml of the 0.9% saline solution. Radiographs were made post-operatively, and after 15, 30, 45 and 90 days. Fifty percent of the samples were submitted to a histological examination at 45 days and the remaining ones at 90 days post-operatively. Radiographically, the periosteal reaction, bone callus volume and bone bridge quality were superior in G2 (P < 0.05). Histologically, the bone repair was faster and more efficient in G1 at 45 days (P < 0.05). In conclusion, AAD-MSC improved the regeneration on the experimentally induced bone defects in rabbits; however, the use of hydroxyapatite requires caution given the granulomatous reaction produced in the species.

Rabbit haemorrhagic disease virus Lagovirus europaeus/GI.1d strain: genome sequencing, in vivo virus replication kinetics, and viral dose effect.

BACKGROUND: Rabbit haemorrhagic disease virus Lagovirus europaeus/GI.1d variant (GI.1d/RHDV) was identified in 1990 in France, and until the emergence of the new genotype GI.2, it was the main variant circulating in the country. The early stages of RHDV infection have been described in a few studies of rabbits experimentally infected with earlier strains, but no information was given on the minimum infective dose. We report the genomic and phenotypic characterisation of a GI.1d/RHDV strain collected in 2000 in France (GI.1d/00-21). RESULTS: We performed in vivo assays in rabbits to study virus replication kinetics in several tissues at the early stage of infection, and to estimate the minimum infective dose. Four tested doses, negligible (10- 1 viral genome copies), low (104), high (107) and very high (1011) were quantified using a method combining density gradient centrifugation of the viral particles and an RT-qPCR technique developed to quantify genomic RNA (gRNA). The GI.1d/00-21 genome showed the same genomic organisation as other lagoviruses; however, a substitution in the 5' untranslated region and a change in the potential p23/2C-like helicase cleavage site were observed. We showed that the liver of one of the two rabbits inoculated via the oral route was infected at 16 h post-infection and all tissues at 39 h post-infection. GI.1d/00-21 induced classical RHD signs (depression) and lesions (haemorrhage and splenomegaly). Although infective dose estimation should be interpreted with caution, the minimum infective dose that infected an inoculated rabbit was lower or equal to 104 gRNA copies, whereas between 104 and 107 gRNA copies were required to also induce mortality. CONCLUSIONS: These results provide a better understanding of GI.1d/RHDV infection in rabbits. The genome analysis showed a newly observed mutation in the 5' untranslated region of a lagovirus, whose role remains unknown. The phenotypic analysis showed that the pathogenicity of GI.1d/00-21 and the replication kinetics in infected organs were close to those reported for the original GI.1 strains, and could not alone explain the observed selective advantage of the GI.1d strains. Determining the minimum dose of viral particles required to cause mortality in rabbits is an important input for in vivo studies.

Rabbits - their domestication and molecular genetics of hair coat development and quality.

The European rabbit (Oryctolagus cuniculus) is the only representative of its genus living in present-day Europe and North Africa, and all domestic rabbits are descendants of this one species, which is native to the Iberian Peninsula. There are over 300 breeds of rabbits that differ in size, coat color, length of ears and type of fur. Rabbits are bred for various reasons, such as for laboratory animals and a source of meat, wool and fur, as well as for pets and exhibition animals. The hair coat is a important economic trait of rabbits. Its development and quality are influenced by various factors, both environmental and genetic. The genetic mechanisms underlying its development have not been thoroughly researched. The aim of this review is to discuss the domestication of rabbits and the different aspects of rabbit genetics. A brief review of the properties of rabbit hair coat, hair coat development and hair cycle will be provided, followed by discussion of the factors regulating hair coat development, molecular control of hair coat development and the role of non-coding RNAs in the regulation of gene expression in the hair follicles of rabbits. Information about genetic regulation of pathways could provide useful tools for improving hair coat quality and be of practical use in rabbit breeding.

Computed tomography with Hounsfield unit assessment is useful in the diagnosis of liver lobe torsion in pet rabbits (Oryctolagus cuniculus).

Clinical signs of liver lobe torsion in rabbits are often nonspecific and mimic those that are also generally detected with gastrointestinal stasis. Nonspecific clinical signs may result in pursuit of full-body imaging such as computed tomography (CT). The aim of this multicenter, retrospective, case series study was to describe CT findings of liver lobe torsion in a group of rabbits. Computed tomography studies of six rabbits with confirmed liver lobe torsion by surgery or necropsy were evaluated. The caudate liver lobe was affected in six out of six rabbits and was enlarged, rounded, hypoattenuating, heterogeneous, and minimally to noncontrast enhancing, with scant regional peritoneal effusion. Precontrast, mean Hounsfield units (HU) of the torsed liver lobe (39.3 HU [range, 24.4-48.1 HU]) were lower than mean HU of normal liver (55.1 HU [range, 49.6-60.8 HU]), with a mean torsed:normal HU ratio of 0.71 (range, 0.49-0.91). Postcontrast, mean HU of the torsed liver lobe (38.4 HU [range, 19.7-48.9 HU]) were also lower than mean HU of normal liver (108.4 HU [range, 84.5-142.0 HU]), with a lower postcontrast mean torsed:normal HU ratio of 0.35 (range, 0.14-0.48) compared to precontrast. Mean HU of torsed liver lobes had little difference pre- and postcontrast (postcontrast HU 1.0 times the average precontrast HU [range, 0.81-1.1]), and contrast enhancement of the torsed liver lobes was on average 50% lower than in normal liver. Liver lobe torsion should be considered in rabbits with an enlarged, hypoattenuating, heterogeneous, minimally to noncontrast enhancing liver lobe, particularly the caudate lobe, and scant regional peritoneal effusion.

Models of spatiotemporal variation in rabbit abundance reveal management hot spots for an invasive species.

The European rabbit (Oryctolagus cuniculus) is a notorious economic and environmental pest species in its invasive range. To better understand the population and range dynamics of this species, 41 yr of abundance data have been collected from 116 unique sites across a broad range of climatic and environmental conditions in Australia. We analyzed this time series of abundance data to determine whether interannual variation in climatic conditions can be used to map historic, contemporary, and potential future fluctuations in rabbit abundance from regional to continental scales. We constructed a hierarchical Bayesian regression model of relative abundance that corrected for observation error and seasonal biases. The corrected abundances were regressed against environmental and disease variables in order to project high spatiotemporal resolution, continent-wide rabbit abundances. We show that rabbit abundance in Australia is highly variable in space and time, being driven primarily by internnual variation in temperature and precipitation in concert with the prevalence of a non-pathogenic virus. Moreover, we show that internnual variation in local spatial abundances can be mapped effectively at a continental scale using highly resolved spatiotemporal predictors, allowing "hot spots" of persistently high rabbit abundance to be identified. Importantly, cross-validated model performance was fair to excellent within and across distinct climate zones. Long-term monitoring data for invasive species can be used to map fine-scale spatiotemporal fluctuations in abundance patterns when accurately accounting for inherent sampling biases. Our analysis provides ecologists and pest managers with a clearer understanding of the determinants of rabbit abundance in Australia, offering an important new approach for predicting spatial abundance patterns of invasive species at the near-term temporal scales that are directly relevant to resource management.