Horn Size Research Articles

Digest: Sexually selected weapons: Winning the fight, but losing the war for reproduction on a changing battlefield*

What conditions favor the evolution of large animal weapons? In the Japanese rhinoceros beetle, Trypoxylus dichotomus, del Sol et al. found that selection favors large horns in populations where males compete over guardianship of scarce female feeding territories. However, in other populations, an abundance of female feeding territories reduces the chance of mating success for these guarding males, leading to the evolution of relatively shorter horn sizes. This finding illustrates that female habitat and resource use have the potential to influence evolution of male weapon size through sexual selection.

Material properties of bighorn sheep (Ovis canadensis) horncore bone with implications for energy absorption during impacts

Bighorn sheep rams participate in high impact head-butting without overt signs of brain injury, thus providing a naturally occurring animal model for studying brain injury mitigation. Previously published finite element modeling showed that both the horn and bone materials play important roles in reducing brain cavity accelerations during ramming. However, in that study the elastic modulus of bone was assumed to be similar to that of human bone since the modulus of ram bone was unknown. Therefore, the goal of this study was to quantify the mechanical properties, mineral content, porosity, and microstructural organization of horncore cortical bone from juvenile and adult rams. Mineral content and elastic modulus increased with horn size, and porosity decreased. However, modulus of toughness did not change with horn size. This latter finding raises the possibility that the horncore cortical bone has not adapted exceptional toughness despite an extreme loading environment and may function primarily as an interface material between the horn and the porous bone within the horncore. Thus, geometric properties of the horn and horncore, including the porous bone architecture, may be more important for energy absorption during ramming than the horncore cortical bone. Results from this study can be used to improve accuracy of finite element models of bighorn sheep ramming to investigate these possibilities moving forward.

Can the radiological scale “iNPH Radscale” predict tap test response in idiopathic normal pressure hydrocephalus?

BackgroundIdiopathic normal pressure hydrocephalus (iNPH) presents typical radiological signs that have been summarised in a semi-quantitative scale named the iNPH Radscale. However, the iNPH Radscale's predictive value for response to cerebrospinal fluid (CSF) tap test has never been studied. This study aims to investigate if the iNPH Radscale can predict locomotion improvement after CSF tap test. MethodsA total of 100 patients with iNPH (age: 76.3 ± 7.9, gender: 36% female) were included in this retrospective study. Two raters, blinded to the response of the CSF tap test, evaluated the iNPH Radscale and its seven subitems (Evan's index, callosal angle, size of temporal horns, narrow high-convexity sulci, dilated Sylvian fissures, focally dilated sulci, and periventricular hypodensities). Locomotion improvement was assessed by the Timed Up and Go (TUG) performed before, and 24 h after, the CSF tap test. ResultsThe iNPH Radscale (total score) was similar between the CSF tap test responders and non-responders (responders: 8.31 ± 1.96, non-responders: 9.18 ± 2.51, p = 0.128). However, the temporal horns score was smaller in the responders group (1.66 ± 0.57 versus 1.94 ± 0.24, p = 0.045), even after adjusting for age, gender, education level, white matter changes, and global cognition (β: -0.250, C.I. 95%: [−3.185; −0.161], p = 0.031). ConclusionThe iNPH Radscale (total score) does not predict locomotion improvement after CSF tap test, while a smaller temporal horns score at baseline is associated with a positive tap test responder status.

Male mating behaviour affects growth of secondary sexual traits: a mechanism for rapid phenotypic change

Intra- and intersexual selection drives the evolution of secondary sexual traits, leading to increased body size, trait size and generally increased reproductive success in bearers with the largest, most attractive traits. Evolutionary change through natural selection is often thought of primarily in terms of genetic changes through mutations and adaptive selection. However, this view ignores the role of the plasticity in phenotypes and behaviour and its impact on accelerating or decelerating the expression of sexually selected traits. Here, we argue that sudden changes in selection pressures (e.g. predation pressure) may cause a cascade of behavioural responses, leading to a rapid change in the size of such traits. We propose that selective removal of individuals with the most prominent traits (such as large antlers or horns in male ungulates) induces behavioural changes in the surviving males, leading to a reduction in the growth of these traits (phenotypic expression). To test this idea, we used an individual-based simulation, parametrized with empirical data of male bighorn sheep, Ovis candensis. Our model shows that the expression (phenotype, not genotype) of the trait under selection (here horn size) can be negatively impacted, if the biggest, most dominant males in the population are removed. While the selective removal of prime males opens breeding opportunities for younger, smaller males, we predicted that it would come at the expense of growth and maintenance. As predicted, we observed a rapid decline in average male horn length in our model. We argue that this decline happens because smaller males, instead of allocating energy into growth, divert this energy towards participation in mating activities that are typically exclusively available to prime males. While our model deals with ecological life-history trade-offs, it cannot predict evolutionary outcomes. However, this nongenetic mechanism is important for the understanding of evolutionary processes because it describes how heritable traits can rapidly change because of behavioural plasticity, long before any genetic changes might be detectable.

Sexual dimorphism in the horn size of a pair-forming coral reef butterflyfish.

Sexual dimorphism is a common in the animal kingdom and is often linked to mate choice or competition for mates in polygynous mating systems. However, sexual dimorphism is less common in species that form heterosexual pairs and has not been recorded in pair-forming coral-reef fish. Here we demonstrate a pronounced morphological difference between males and females in the humphead bannerfish (Heniochus varius)—a pair-forming coral reef butterflyfish. Males of paired individuals collected in Kimbe Bay, Papua New Guinea had substantially larger hump and horn protrusions on their heads than females. Fish were also sexed, sized and aged to determine the reproductive and demographic basis of the pairing behaviour. H. varius pairs were exclusively heterosexual and were assorted strongly by total length and slightly less so by age. Females in pairs were generally the same size as male partners, but were frequently older by a year and sometimes more. Hump and horn lengths increased proportionally to body-size in both sexes, with horns growing at a greater rate among males. These findings suggest that H. varius form pairs primarily for reproductive purposes, with selection via a size-assortative process that likely also extends to selection for larger hump and horn protrusions among males. The larger humps and horns in males appear to be the first recorded example of a secondary sexual morphological characteristic in a pair-forming coral reef fish species.

Reproductive Aggregations of Dynoides dentisinus (Crustacea: Peracarida), an Intertidal Isopod with Remarkable Sexual Dimorphism.

AbstractThe intertidal isopod Dynoides dentisinus is a sexually dimorphic species; males are much larger than females and have a large, horn-like pleonal process (hereafter referred to as a "horn") and large, posteriorly extended uropods. Here, we investigated the function of these structures with regard to their mating system. Behavioral interactions were observed between a male occupying a small tube (resident) and a newly introduced individual (a female or male visitor). When the visitor was male, the resident repeatedly struck the visitor with his horn; each swing was accompanied by a short sound produced by stridulation. The resident also used his uropods to strike the male visitor and then rejected the visitor. The resident struck the female visitor in a similar fashion but eventually accepted her into the tube; during this process, the resident frequently emitted stridulatory sounds. Our field survey found that the members shared a single shelter (barnacle shell) containing groups composed of several males and females. This suggests that the mating system of this species is polygynandry. The number of females in a single barnacle shell was positively associated with the basal diameter of the barnacle shell. However, the number of females was not associated with the body size, horn size, or uropod size of the largest male in the barnacle shell. These results suggest that male body size, horns, and uropods might have evolved as weapons through male-male competition for large barnacle habitats and more females, but that they have not evolved as ornaments via female choice.

Evaluation of cervical and uterine size, at 4weeks postpartum, as a predictor of subsequent fertility in Jersey cattle.

Uterine and cervical size of Holstein dairy cows is reported among reasons for a decline in dairy cow fertility. Therefore, the objectives of this study were to (a) determine whether size of the cervix and uterus at 4weeks postpartum impacted subsequent fertility at first service in Jersey cattle, (b) determine whether progesterone level at 4weeks postpartum impacted cyclicity and (c) the association of the presence of corpus luteum and uterus and cervix size. Body condition scores at calving, presence of postpartum diseases, parity number and milk weights were taken from lactating Jersey dairy cows (N=147) for 28days postpartum. During the fourth week postpartum, a blood sample was obtained for progesterone concentration, and transrectal ultrasonography was performed by a high-resolution ultrasound machine to determine cervical and uterine horn diameter, as well as ovarian structures measurements. Correcting for parity number, BCS at calving, presence of diseases and milk yield, cows with a cervix >2.54±0.63cm and uterine horn >2.25±0.59cm were less likely to become pregnant at first service (p=.04 and p=.003, respectively). The cows with larger cervix had a trend to be less likely to have a corpus luteum present at the 4th week of lactation (p=.067). Cows with larger uterine horn size were less likely to have a corpus luteum present at the 4th week of lactation (p=.015). It is concluded that a larger cervix and/or uterus during the postpartum was associated negatively with fertility and cyclicity in Jersey cows.

Breeding practices and trait preferences of smallholder farmers for indigenous sheep in the northwest highlands of Ethiopia: Inputs to design a breeding program.

The aim of this study was to identify breeding practices and trait preferences for indigenous sheep in three districts (Estie, Farta and Lay Gayient) located in the northwest highlands of Ethiopia. Questionnaire survey and choice experiment methods were used to collect data from 370 smallholder farmers. Respondents were selected randomly among smallholder farmers who own sheep in the aforementioned districts. A generalized multinomial logit model was employed to examine preferences for sheep attributes, while descriptive statistics and index values were computed to describe sheep breeding practices. Having the highest index value of 0.36, income generation was ranked as the primary reason for keeping sheep, followed by meat and manure sources. The average flock size per smallholder farmer was 10.21 sheep. The majority of the smallholder farmers (91%) have the experience of selecting breeding rams and ewes within their own flock using diverse criteria. Given the highest index value of 0.34, body size was ranked as a primary ram and ewe selection criteria, followed by coat color. Furthermore, choice modeling results revealed that tail type, body size, coat color, growth rate, horn and ear size have shown significant influences on smallholder farmers' preference for breeding rams (P<0.01). The part-worth utility coefficients were positive for all ram attributes except ear size. For breeding ewes, mothering ability, coat color, body size, lambing interval, growth rate, tail type and litter size have shown significant effects on choice preferences of smallholder farmers (P<0.05). Moreover, significant scale heterogeneity was observed among respondents for ewe attributes (P<0.001). Overall, the results implied that sheep breeding objectives suitable for the northwest highlands of the country can be derived from traits such as linear body measurement, weight and survival at different ages, and lambing intervals. However, selection decisions at the smallholder level should not only be based on estimated breeding values of traits included in the breeding objective but instead, incorporate ways to address farmers' preference for qualitative traits.

Testing the importance of harvest refuges for phenotypic rescue of trophy‐hunted populations

Abstract Sustainable exploitation must minimize its impact on the ecology and evolution of exploited wildlife. Intense phenotype‐based selective harvests can induce evolutionary change. Refuges could mitigate those evolutionary effects if individuals not subject to selective hunting in harvest refuges migrated and reproduced in hunted areas. The role of harvest refuges on phenotypic rescue of trophy‐hunted species, however, has rarely been tested. We investigated spatial and temporal variation in the effect of refuges on horn size and age at harvest in bighorn sheep Ovis canadensis. We analysed data on 5,826 males harvested over 39 years in Alberta, Canada. Horn length, a trait targeted by hunters, and age at harvest increased with the amount of protected areas 5–40 km around each kill. Horn base circumference, however, was independent of proximity to refuges. The number of males harvested increased during the last 10 days of the hunting season in late October, corresponding to the timing of bighorn male breeding migrations. Males shot during those 10 days were on average 17% closer to a refuge than males shot earlier in the season. Apparently, some large males exit refuges late in the hunting season, are shot, and cannot contribute to rescue. Uncertainty remains about the proportion of males exiting refuges after the hunting season and how many survive to reproduce. Synthesis and applications. Harvest refuges are unlikely to rescue hunted populations of bighorn sheep in Alberta, because some males exiting refuges are at risk of harvest before they mate. For phenotypic rescue to be effective, unselected males must reproduce before they are shot. Closing the hunting season 10 days earlier would increase survival of unselected rams exiting refuges.

Notch signaling patterns head horn shape in the bull-headed dung beetle Onthophagus taurus.

Size and shape constitute fundamental aspects in the description of morphology. Yet while the developmental-genetic underpinnings of trait size, in particular with regard to scaling relationships, are increasingly well understood, those of shape remain largely elusive. Here we investigate the potential function of the Notch signaling pathway in instructing the shape of beetle horns, a highly diversified and evolutionarily novel morphological structure. We focused on the bull-headed dung beetle Onthophagus taurus due to the wide range of horn sizes and shapes present among males in this species, in order to assess the potential function of Notch signaling in the specification of horn shape alongside the regulation of shape changes with allometry. Using RNA interference-mediated transcript depletion of Notch and its ligands, we document a highly conserved role of Notch signaling in general appendage formation. By integrating our functional genetic approach with a geometric morphometric analysis, we find that Notch signaling moderately but consistently affects horn shape, and does so differently for the horns of minor, intermediate-sized, and major males. Our results suggest that the function of Notch signaling during head horn formation may vary in a complex manner across male morphs, and highlights the power of integrating functional genetic and geometric morphometric approaches in analyzing subtle but nevertheless biologically important phenotypes in the face of significant allometric variation.

Review on Production Systems, Farmers Trait Preferences and Breeding Practice of Indigenous Sheep Breeds in Ethiopia

In Ethiopia sheep serve as a source of income, meat, milk, skin, manure and employment for smallholder rural farmers. Sheep are the most preferred animals by rural poor communities as they require small investment, have shorter production cycles faster growth rates and greater environmental adaptability as compare to large ruminant. The objective of this senior seminar is reviewing on Production Systems, Selection criteria and Breeding practice of indigenous Sheep Breeds in Ethiopia. Rural households are practicing animal husbandry in diverse production systems and climatic zone which are classified as three major different production systems; highland sheep-barely, mixed crop-livestock and pastoral and agro-pastoral production systems. However, sheep production and productivity in the country is challenged by scarcity of feed, diseases outbreak, poor infrastructure, lack of market information, lack of knowledge, absence of planned breeding programs and policies. The existed sheep type in the country is really the output of human intervention and natural selection. Traits like coat color, tail type, horn and ear size of sheep can also have dynamic effect on the price of sheep marketing. For selecting breeding ram’s farmers consider different traits like body conformation, coat color, tail type/size, growth rate, sexual drives, dentation and the quality of being adapted and record of ancestors. Breeding ewes are selected by farmers as a replacement stock based on their Coat color, twining ability, lamb growth, lamb survival, age at first lambing and lambing intervals. In Ethiopia the main objective of sheep production is to provide income, meat, milk, skin, manure and employment for smallholder rural farmers. In Ethiopia both pure-breeding and crossbreeding are the most common sheep breeding practice. Farmers practice both selection and crossbreeding to improve their breeding stocks. Therefore, the economic value each trait should be assessed because it influenced the market value of sheep and the decision of farmers in selecting breeding stocks. The establishment of standard marketing systems and market information calls further investigation.

Mate choice, reproductive success and inbreeding in white rhinoceros: New insights for conservation management.

Improving our sparse knowledge of the mating and reproductive behaviour of white rhinoceros (Ceratotherium simum Burchell, 1817) is essential for the effective conservation of this iconic species. By combining morphological, physiological and habitat data with paternity assignments of 104 known mother–offspring pairs collected over a period of 13 years, we provide the most comprehensive analysis of the mating system in this species. We show that while the overall mating system was promiscuous, and both males and females produced more offspring when mating with several partners, half of all females with multiple offspring were monogamous. Additionally, we find that mating and reproductive success varied significantly among territorial males in two independent sets of males. In females, however, variation in the mating and the reproductive success was not larger than expected by random demographic fluctuations. Horn size, testosterone metabolite concentration, territory size, habitat openness and the volume of preferred food within the territory did not seem to influence male mating or reproductive success. Moreover, there was no sign of inbreeding avoidance: females tended to mate more frequently with closely related males, and one daughter produced a progeny with her father. The lack of inbreeding avoidance, in combination with the skew in male reproductive success, the partial monogamy in females and the territorial‐based mating system, jeopardizes the already low genetic variation in the species. Considering that the majority of populations are restricted to fenced reserves and private farms, we recommend taking preventive measures that aim to reduce inbreeding in white rhinoceros. A video abstract can be viewed here.

Predicting the Potential Impacts of Trophy Hunting on Population Structure of Himalayan Ibex (Capra sibirica) in Northern Pakistan

We compared population structure and trophy hunting statistics of Himalayan ibex (Capra sibirica) in two community-controlled hunting areas (CCHAs) of northern Pakistan with varying duration of trophy hunting and isolated populations of C. sibirica. Based on fixed-point direct count method during winter 2016–2017, 939 ibexes were counted in Khyber and 346 in Hussaini, with a density of 7.5 and 3.2 animals km-2, respectively. Though the populations of C. sibirica at both the study sites have increased compared to the past estimates, we found variations in population structures and horn sizes, presumably as a result of trophy hunting. The sex ratios are skewed toward females in Khyber (87 males/100 females) and towards males in Hussaini (115 males/100 females). The trophy size males were 7% of the population in Khyber and 11% in Hussaini. Mean group (herd) size in Khyber was 28 (range = 1–117) and Hussaini was 20 (range = 1–79). Mean horn size of the trophies harvested in Khyber was 102 cm (± range = 91–114) compared to 108 cm (range = 99–121) in Hussaini. Stringent regulatory measures are suggested to determine the number of permits.

Inter- and intra-site differences in wild goat (Capra aegagrus) habitat quality detected through male horn size comparisons in Greek islands

In caprid taxa, horn size is correlated with body mass, being a potential indicator of habitat quality. In this study, horn length and circumference measurements of, genetically similar, native island (Samaria National Forest Park, Crete) and introduced islet (a Game Breeding Station, and a Controlled Hunting Zone) populations of the Vulnerable agrimi were compared and evaluated with respect to population size information. Horns belonged to male animals that died between 1975 and 2016. There were significant age-related differences in inner horn length (annual increments and total) and annulus circumference between the three areas reflecting differences in food resources. Longest horns currently grow in the Controlled Hunting Zone. Length appeared negatively associated with population density. Results, also, showed that, in the short term, forage improvement can reverse horn size decrease trends. To support conservation efforts, it is suggested that native range and islet managers should establish horn measuring in monitoring practices.

Density-dependent decline of early horn growth in European mouflon

The development of horns in Caprinae can be largely influenced by food-limiting factors such as population density and climate, as well as by negative evolutionary responses to size-selective harvesting. In this study, we investigated the effects of population density, environmental covariates and trophy hunting on horn development in a population of European mouflon Ovis aries musimon introduced to the Mediterranean region of Croatia in the early 1980s. The study population was subject to commercial trophy hunting on males since the mid-1980s. This allowed to analyse the temporal trend in early horn growth in 341 rams legally culled. Cohort-based linear model and analysis of deviance (ANODEV) revealed a significant negative trend in early horn growth, with a decline of ca. 10% over only 15 cohorts (1993–2007). The increase in population density (by ca. 600%) and summer temperature, selected via LASSO regression, explained about 61% and 13% of the decline in early horn growth, as revealed by the ANODEV R2. Our results suggest a prominent role of food-limiting factors in the decline of weapon size. We also found a negative relationship between age at death and early horn growth in our study population, which suggests the occurrence of hunters’ selectivity towards large horns. The effect of trophy hunting on the decline in horn size, however, is difficult to quantify. Our analysis was largely influenced by the rapid increase of mouflon density after introduction, thereby limiting the possibility to detect potential effects of hunting selection, although the large number of rams shot before 5 years of age may possibly lead to undesirable consequences of trophy hunting on mating success. To clarify the consequences of commercial trophy hunting on the mouflon population, the long-term pattern of horn growth and the age-dependent male siring success should be further investigated.

1655 Laparoscopic Unification of Non Communicating Horn with Hemi-Uterus

Video Objective To demonstrate new idea of laparoscopic unification of functional non – communicating horn with hemi-uterus instead of removal to improve obstetric outcome in future. Setting an academic tertiary care hospital. A 14-year-old girl presented with complaints of pain in lower abdomen, on and off for 2 months. Her previous 2 cycles were regular; she had cyclic dysmenorrhoea since her menarche which was now become intolerable and continuous. Secondary sexual characteristic was normal. hormone profile normal and on local examination normal external genitalia found. A thin dilator passed into vagina to confirm patent vagina. ultrasound suggested a unicornuate hemi uterus and right non communicating horn with a turbid collection. MRI also confirm the same. Interventions On Hysteroscopy a small right uterine cavity with only one ostium on right. Cervical canal was normal with normal crypts. vagina also normal and spacious. On diagnostic laparoscopy: A unicornuate right hemi- uterus with a non-communicating left horn was noted on the right side of the round ligament, tube and ovary were seen normal with small hemi-uterus. On the left, small uterine horn seen with absent tube but normal ovary and round ligament attachment. First, we were planned resection of non-communicating horn as described in literature but after assessing the anatomical proximity and good size of horn and small size of hemi-uterus we decided for unification of both. After injecting diluted inj. vasopressin, linear medial incision given in full thickness of myometrium with monopolar energy and opening the cavity with scissors. Both the walls sutured together first posteriorly and then anteriorly in double layer with no. 1 polyglactin 910 suture. Conclusion Good normal size, shape and contour of uterus appreciated after completion of procedure. After surgery patient had one normal menses without any pain suggest success of surgery.

Heritability of Horn Size in Thinhorn Sheep.

Understanding the genetic basis of fitness-related trait variation has long been of great interest to evolutionary biologists. Secondary sexual characteristics, such as horns in bovids, are particularly intriguing since they can be potentially affected by both natural and sexual selection. Until recently, however, the study of fitness-related quantitative trait variation in wild species has been hampered by a lack of genomic resources, pedigree, and/or phenotype data. Recent innovations in genomic technologies have enabled wildlife researchers to perform marker-based relatedness estimation and acquire adequate loci density, enabling both the “top-down” approach of quantitative genetics and the “bottom-up” approach of association studies to describe the genetic basis of fitness-related traits. Here we combine a cross species application of the OvineHD BeadChip and horn measurements (horn length, base circumference, and volume) from harvested thinhorn sheep to examine the heritability and to perform a genome-wide single-nucleotide polymorphism association study of horn size in the species. Thinhorn sheep are mountain ungulates that reside in the mountainous regions of northwestern North America. Thinhorn sheep males grow massive horns that determine the social rank and mating success. We found horn length, base circumference, and volume to be moderately heritable and two loci to be suggestively associated with horn length.

Computerized predictive model for differential diagnosis of normal pressure hydrocephalus based on complex analysis of MRI image

Background. The main problem is to differentiate idiopathic normal pressure hydrocephalus (iNPH) with other neurodegenerative diseases accompanied by similar clinical presentation. For this purpose, a number of neuroimaging and invasive methods were proposed. The study objective is to assess most reliable magnetic resonance (MR) symptoms of iNPH and to create a prognostic model for differential diagnosis of iNPH by these criteria. Materials and methods. MR-data of 213 iNPH, 144 neurodegenerative (Alzheimer disease, Parkinson disease and early mild cognitive impairment) patients and 79 healthy age-matched controls were retrospectively analyzed. Following criteria were assessed: Evans Index, size of the third ventricle, size of temporal horns, disproportionately enlarged subarachnoid space hydrocephalus, focal convexital sulci enlargement, callosal angle, periventricular hyperintensities, focal subcortical gliosis and perivascular spaces enlargement. One-way ANOVA was used to explore differences between groups. Classification matrix was formed by discriminant analysis. Results. Differential model was established and Excel-tab-calculator was created for complex computed assessment of MR data and differential diagnosis of iNPH patients. Prognostic accuracy of model for iNPH reaches 99.5 %, for degenerative disorders – 89 %, common diagnostic accuracy is 92 %. Conclusion. Advantages of complex approach for assessment of MR-data in iNPH patients were underlined. Prognostic model for prediction of iNPH based on MR criteria was established.

Biological relevance of antler, horn, and pronghorn size in records programs

AbstractLong-term datasets are becoming increasingly important for assessing population- and species-level responses to a changing environment. Programs that record morphological measurements of horns, antlers, and pronghorns were established in the early- to mid-20th century to collect biological information about animals that possess large horns, antlers, or pronghorns, which could be used to assess the effectiveness of conservation efforts for large mammals in North America. The general relevance of record books has been questioned because of the minimum size requirements for inclusion in a record book, which may mask trends when changes in the population occur. We compared trends in size of antlers, horns, and pronghorns through time using records from three records programs with different minimum size requirements to evaluate the influence of entry requirements on temporal trends. We also investigated whether horn, antler, or pronghorn size affected the probability of specimens being submitted to a records program. Only two of 17 categories exhibited less-pronounced trends in the record book with the highest size requirements for entry, and in two categories trends were more pronounced. Although societal interest in submitting eligible specimens increased slightly over time in one of six categories, the probability of voluntary entry was largely random and not affected by year of harvest or size of specimen. In contrast to previous criticisms, trends in record books should not be expected to represent the size of all males within a population. Instead, our evaluation indicates that the records programs we examined can provide a useful resource for assessing long-term changes in phenotypic characteristics of ungulates, but importantly, they represent the respective range of sizes within which each program collects data.

Standardized image evaluation in patients with idiopathic normal pressure hydrocephalus: consistency and reproducibility

PurposeAssess the agreement for two investigators between computed tomography (CT) and magnetic resonance imaging (MRI) for seven imaging features included in the iNPH Radscale, a radiological screening tool.MethodsThe study included 35 patients with idiopathic normal pressure hydrocephalus (iNPH) who were treated surgically from 2011 to 2015 at Uppsala University Hospital with preoperative CT and MRI performed with maximum 3 months between scans. Seven features were assessed: Evans’ index, temporal horn size, callosal angle, periventricular white matter changes, narrow high convexity sulci, focally enlarged sulci, and enlarged Sylvian fissures. All scans were assessed by two investigators who were blinded to each other’s results and to clinical data.ResultsThe agreement between CT and MRI was almost perfect for Evans’ index, temporal horns, narrow sulci, and Sylvian fissures (kappa and intraclass correlation, 0.84–0.91, p ≤ 0.001). There was substantial to almost perfect agreement for callosal angle and focally enlarged sulci. The concordance between modalities was fair for changes in periventricular white matter.ConclusionCT and MRI are equally good for assessing radiological signs associated with iNPH except for periventricular white matter changes, as MRI has superior soft tissue contrast. The other imaging features can be evaluated consistently, and assessments are reproducible independent of modality. Therefore, the iNPH Radscale is applicable to both CT and MRI and may become an important tool for standardized evaluation in the workup in patients with suspected iNPH.