Hurricane effects on Neotropical lizards span geographic and phylogenetic scales.

Extreme climate events such as droughts, cold snaps, and hurricanes can be powerful agents of natural selection, producing acute selective pressures very different from the everyday pressures acting on organisms. However, it remains unknown whether these infrequent but severe disruptions are quickly erased by quotidian selective forces, or whether they have the potential to durably shape biodiversity patterns across regions and clades. Here, we show that hurricanes have enduring evolutionary impacts on the morphology of anoles, a diverse Neotropical lizard clade. We first demonstrate a transgenerational effect of extreme selection on toepad area for two populations struck by hurricanes in 2017. Given this short-term effect of hurricanes, we then asked whether populations and species that more frequently experienced hurricanes have larger toepads. Using 70 y of historical hurricane data, we demonstrate that, indeed, toepad area positively correlates with hurricane activity for both 12 island populations of Anolis sagrei and 188 Anolis species throughout the Neotropics. Extreme climate events are intensifying due to climate change and may represent overlooked drivers of biogeographic and large-scale biodiversity patterns.

The same but different: setal arrays of anoles and geckos indicate alternative approaches to achieving similar adhesive effectiveness.

The functional morphology of squamate fibrillar adhesive systems has been extensively investigated and has indirectly and directly influenced the design of synthetic counterparts. Not surprisingly, the structure and geometry of exemplar fibrils (setae) have been the subject of the bulk of the attention in such research, although variation in setal morphology along the length of subdigital adhesive pads has been implicated to be important in the effective functioning of these systems. Adhesive setal field configuration has been described for several geckos, but that of the convergent Anolis lizards, comprised of morphologically simpler fibrils, remains largely unexplored. Here, we examine setal morphology along the proximodistal axis of the digits of Anolis equestris and compare our findings to those for a model gecko, Gekko gecko. Consistent with previous work, we found that the setae of A. equestris are generally thinner, shorter, and present at higher densities than those of G. gecko and terminate in a single spatulate tip. Contrastingly, the setae of G. gecko are hierarchically branched in structure and carry hundreds of spatulate tips. Although the splitting of contacts into multiple smaller tips is predicted to increase the adhesive performance of a fiber compared to an unbranched one, we posited that the adhesive performance of G. gecko and A. equestris would be relatively similar when the configuration of the setal fields of each was accounted for. We found that, as in geckos, setal morphology of A. equestris follows a predictable pattern along the proximodistal axis of the pad, although there are several critical differences in the configuration of the setal fields of these two groups. Most notably, the pattern of variation in setal length of A. equestris is effectively opposite to that exhibited by G. gecko. This difference in clinal variation mirrors the difference in the direction in which the setal fields of anoles and geckos are peeled from the substrate, consistent with the hypothesis that biomechanical factors are the chief determinants of these patterns of variation. Future empirical work, however, is needed to validate this. Our findings set the stage for future comparative studies investigating the functional morphology of these convergent adhesive apparatuses. Such investigations will lead to an enhanced understanding of the interactions between form, function, and environment of fibril-based biological adhesive systems.

Overexpression of Androgen Receptors Masculinizes 2D:4D Digit Ratios in Mice.

Studying the role of the prenatal endocrine environment in humans is challenging due to the ethical and practical considerations of measuring hormone levels of the developing fetus. Because it has been difficult to ascertain whether prenatal androgens contribute to the brain and behavior in humans as it does in non-human species, retrospective markers of prenatal androgens, such as the second-to-fourth finger digit ratio (2D:4D), are of interest to the studying of human behavioral endocrinology. To assess the validity of such markers, laboratory animals have been studied. Some strains of mice have been reported to show a sex difference in 2D:4D, and pharmacological and genetic manipulation of the androgen and estrogen receptors (AR and ER) has implicated a role for prenatal androgens in mediating this sex difference, although there have been conflicting reports. Here, we compared mice with global AR overexpression to mice with wildtype (WT) littermates and mice with neural-specific AR overexpression. We found a sex difference in the right hind paw, such that males had larger digit ratios than females. Regardless of sex, mice with global AR overexpression showed an increase in the right hind 2D:4D ratio compared with both WT and neural-specific AR overexpression mice. These results support a role for non-neural AR in the development of 2D:4D and suggest that increased sensitivity to androgens via increased AR is sufficient to increase the masculinization of digit ratios. Future directions for confirming the validity of 2D:4D as a marker for prenatal androgen exposure are discussed.

Using 320-detector row computed tomography angiography to investigate the arterial anatomy of the toe flaps on living humans.

PURPOSE: Using 320-detector row computed tomography angiography (320-CTA) to investigate the arterial supply for the toe flaps, namely the anatomical characteristics of the dorsalis pedis artery (DPA), the first dorsal metatarsal artery (FDMA), and the arteries of the first toe web space (AsFTWS). METHODS: This was a prospective study on CTA of 72 intact feet of 36 Vietnamese adults who had sequelae of thumb or metacarpal hand amputation, from June 2017 to December 2019, then preoperative CTA images were compared with surgical findings on 31 feet of 29 patients. RESULTS: 320-CTA was able to investigate the DPA, FDMA, and AsFTWS in 100% of cases. DPA was absent in 6.9% of cases. The average diameters at its origin and termination were 3.22 and 2.56 mm, respectively. For FDMA, the rates of Gilbert type I, II, and III were 52.8%, 18.1%, and 29.2%; the average diameters at its origin and termination were 1.98 and 1.67 mm, respectively. At the first toe web space, FDMA was dominant in 54.2% of cases; the first plantar metatarsal artery (FPMA) was dominant in 29.2% of cases; both arteries were equally dominant in 16.6%. The average diameter at the origin of the lateral plantar digital artery of the great toe was 1.48 mm, of the medial plantar digital artery of the second toe was 1.21 mm. Preoperative CTA images resembled the surgical findings in all cases. The survival rate of toe flaps was 100%. CONCLUSION: The 320-CTA provided proper preoperative images in two and three dimensions, and helped surgeons to establish a preoperative surgical plan, thus increasing the success rate of toe transfer surgery.

Impact of intertendinous connections between the flexor digitorum brevis and longus on percutaneous tenotomy for the treatment of claw toes: an anatomic and ultrasound study.

PURPOSE: Selective percutaneous tenotomy of the flexor digitorum longus (FDL) is a treatment for claw toes that gives astonishingly good functional results despite tendon sacrifice. However, the involution of the FDL tendon stump after tenotomy is unknown. The aim of our study was to assess the involution of the tendon stump after selective percutaneous tenotomy of the FDL. METHODS: The study included two parts. In the clinical part, an ultrasound analysis of 15 FDL tenotomies in 7 patients was carried out 3 months post-surgery. In the anatomic part, the feet of 10 bodies donated to science were dissected and examined anatomically. RESULTS: The proximal stump of the FDL was located near the base of the proximal phalanx and moved synchronously with the flexor digitorum brevis (FDB).Separating the FDB and FDL revealed a large tissue connection between the plantar surface of the tendinous chiasm of the FDB and the dorsal part of the FDL. These connections had significant resistance ranging from 2 to 9 Newtons depending on the toe. Tenotomy of the FDL followed by proximal traction of it led to retraction of the stump up to the base of the proximal phalanx and transfer of its action to the FDB by tensioning the intertendinous structure. Histologically, these structures were mostly comprised of tendon connective tissue. Their vascular component was small. CONCLUSION: The presence of this intertendinous connection leads, in the case of isolated tenotomy of the FDL, to equivalent transfer of the latter to the FDB.

Axonal regrowth is impaired during digit tip regeneration in mice.

Mice are intrinsically capable of regenerating the tips of their digits after amputation. Mouse digit tip regeneration is reported to be a peripheral nerve-dependent event. However, it is presently unknown what types of nerves and Schwann cells innervate the digit tip, and to what extent these cells regenerate in association with the regenerative response. Given the necessity of peripheral nerves for mammalian regeneration, we investigated the neuroanatomy of the unamputated, regenerating, and regenerated mouse digit tip. Using immunohistochemistry for ß-III-tubulin (ß3T) or neurofilament H (NFH), substance P (SP), tyrosine hydroxylase (TH), myelin protein zero (P0), and glial fibrillary acidic protein (GFAP), we identified peripheral nerve axons (sensory and sympathetic), and myelinating- and non-myelinating-Schwann cells. Our findings show that the digit tip is innervated by two digital nerves that each bifurcate into a bone marrow (BM) and connective tissue (CT) branch. The BM branches are composed of sympathetic axons that are ensheathed by non-myelinating-Schwann cells whereas the CT branches are composed of sensory and sympathetic axons and are ensheathed by myelinating- and non-myelinating-Schwann cells. The regenerated digit neuroanatomy differs from unamputated digit in several key ways. First, there is 7.5 fold decrease in CT branch axons in the regenerated digit compared to the unampuated digit. Second, there is a 5.6 fold decrease in myelinating-Schwann cells in the regenerated digit compared to the unamputated digit that is consistent with the decrease in CT branch axons. Importantly, we also find that the central portion of the regenerating digit blastema is aneural, with axons and Schwann cells restricted to peripheral and distal blastema regions. Finally, we show that even with impaired innervation, digits maintain the ability to regenerate after re-amputation. Taken together, these data indicate that nerve regeneration is impaired in the context of mouse digit tip regeneration.

Comparative genomics reveals convergent evolution between the bamboo-eating giant and red pandas.

Phenotypic convergence between distantly related taxa often mirrors adaptation to similar selective pressures and may be driven by genetic convergence. The giant panda (Ailuropoda melanoleuca) and red panda (Ailurus fulgens) belong to different families in the order Carnivora, but both have evolved a specialized bamboo diet and adaptive pseudothumb, representing a classic model of convergent evolution. However, the genetic bases of these morphological and physiological convergences remain unknown. Through de novo sequencing the red panda genome and improving the giant panda genome assembly with added data, we identified genomic signatures of convergent evolution. Limb development genes DYNC2H1 and PCNT have undergone adaptive convergence and may be important candidate genes for pseudothumb development. As evolutionary responses to a bamboo diet, adaptive convergence has occurred in genes involved in the digestion and utilization of bamboo nutrients such as essential amino acids, fatty acids, and vitamins. Similarly, the umami taste receptor gene TAS1R1 has been pseudogenized in both pandas. These findings offer insights into genetic convergence mechanisms underlying phenotypic convergence and adaptation to a specialized bamboo diet.

Anatomical Differences Between Foot and Hand Web Space Reconstruction.

The differences in the anatomy of the foot and the hand may affect the dorsal flap design for web space reconstruction. In this study, the authors aimed to identify the differences in web space anatomy of the foot and the hand and provide a guideline of flap design for web space reconstruction in the foot and the hand. The right hands and right feet of adult volunteers were measured, including surgical landmarks (i.e., the dorsal prominence of proximal interphalangeal and metacarpophalangeal joints [or metatarsophalangeal joints]), proximal phalangeal length, tip of the web space, and width of web space. The web spaces and other parameters were analyzed and compared between the foot and the hand by using a paired t test with p < .05 to indicate statistical significance. A total of 108 web spaces of the foot and hand from 18 adult volunteers were analyzed. The parameters that were significantly different between the foot and the hand included (1) proximal phalangeal length (34.63 vs 60.16 mm), (2) average web height ratio (0.72 vs 0.51), (3) average web width ratio (0.69 vs 0.81), (4) mean slope angle (4.89° vs 19.26°), and (5) average abduction angle (25.33° vs 31.07°). In conclusion, the foot web space had a higher slope angle, less abduction angle, and shorter proximal phalangeal length. Therefore, the flap design for foot web space reconstruction requires a longer and narrower flap than the design for the hand. The recommended flap design length should be at least 72% of proximal phalangeal length for the foot versus 51% for the hand, and the width should be at least 69% of the distance between the tips of adjacent metatarsophalangeal joints for the foot versus 81% for the hand.

Flexor hallucis longus tendon branch test: Development and validation of a new method to assess anatomical variation of the tendinous slip.

BACKGROUND: The flexor hallucis longus (FHL) muscle often has a tendinous slip with a variable number of branches. We aimed at developing the FHL branch test to determine the number of FHL branches. METHODS: In anatomical validation study, 6 intact cadavers were used. The toe flexion angles were measured while the FHL and flexor digitorum longus (FDL) were manually pulled individually. For electrophysiological studies, 4 healthy men participated. The FHL was electrically stimulated, and electromyography (EMG) of the FHL and FDL were recorded during the FHL branch test. RESULTS: The toe flexion angles' changes in the FHL pulling condition were equivalent with pulling FDL in toes with FHL branching. The electrical stimulation of the FHL produced similar flexion as the FHL branch test. EMG of the FHL was higher than FDL during the FHL branch test (p=0.036). CONCLUSIONS: The FHL branch test could be used to evaluate the number of FHL branches.

Forefoot Pain in the Lesser Toes: Anatomical Considerations and Magnetic Resonance Imaging Findings.

Various conditions may result in forefoot pain. Magnetic resonance (MR) imaging allows accurate assessment of many of these conditions. We provide an overview of forefoot disorders divided into bones, capsule and plantar plate, musculotendinous structures, neurovascular structures, and subcutaneous tissue. We review normal anatomical features as well as MR imaging findings of common disorders.

Does the 2nd and 4th digit ratio reflect prenatal androgen exposure?

OBJECTIVES:  The aim of our study was to describe the effect of prenatal testosterone exposure on 2D:4D in both sexes, and to determine whether this effect is mediated via the androgen receptor. In addition, the sex differences in lengths of 2D, 4D, and 2D:4D ratio were analyzed. BACKGROUND:  Clinical studies suggest a negative correlation between prenatal testosterone exposure and ratio of the lengths of the second and fourth digits (2D:4D). However, less is known about the underlying molecular mechanisms. METHODS:  Pregnant rats were treated with olive oil, testosterone, flutamide or testosterone with flutamide daily from the fourteenth day of pregnancy until delivery. The finger lengths of adult offspring were measured using both, digital scanning of the paws and µCT analysis of the phalanges. RESULTS:  None of the aforementioned methods revealed any effect of testosterone on 2D:4D. µCT measurements showed that prenatal hyperandrogenism in both sexes leads to shorter 2D compared to controls. Moreover, the testosterone treatment in males resulted in the shortening of 4D when compared to controls. CONCLUSION:  Prenatal hyperandrogenism leads to shorter lengths of 2D and 4D; however, it does not affect 2D:4D ratio. Whether other steroid hormones and/or testosterone metabolites affect the 2D:4D ratio requires further investigation (Tab. 5, Fig. 3, Ref. 32).

Additional muscular slip of the flexor digitorum longus muscle to the fifth toe.

Despite the fact that there are numerous reports on muscular variations in the sole of the foot, routine dissection in a formaldehyde-fixed cadaver revealed an accessory flexor digiti quinti muscle, which to the best of our knowledge is a very unusual variant. This was in the form of a slender, 38 mm long muscular slip, with a proximal and distal tendon extending from the common flexor digitorum longus tendinous plate out to the distal phalanx of the fifth toe. An associated finding was the absence of the musculotendinous portion of the flexor digitorum brevis to the same toe. A developmental explanation for this variation is presented. Clinical implications with regard to this anatomical condition may result in clawing of the fifth toe.

The prevalence and ossification pattern of the biphalangeal and triphalangeal lateral toes.

PURPOSE: Biphalangealism of the toes is an exclusively human phenomenon. The aim of this study was to evaluate the development of the lateral toes in childhood by following the ossification pattern of the phalanges. METHODS: Foot radiographs of 913 adults have been evaluated for biphalangealism of 3rd to 5th toe. The pediatric group, aged 6-15 years of age, was assessed for the number of ossification centers in the foot. RESULTS: In adults, the mean prevalence of biphalangealism in the 5th toe was 41.39%, in the 4th toe was 2.15%, and in the 3rd toe was 0.48%. In children, 45% feet had four ossification centers in the 5th toe. The epiphysis center of the middle and distal phalanx was missing. In the 4th toe, four centers were present in of 2.47% of cases. Those values are similar to the prevalence of the biphalangeal toes in adult population. The remaining toes had 5 or 6 ossification centers. In the 5-center toe, the epiphysis of the middle phalanx was missing. CONCLUSION: A missing distal phalanx epiphyseal ossification center is considered indicative of a biphalangeal toe, and the toes with 5 or 6 ossification centers are indicative of triphalangeal toes. The reason for such evolution of the lateral toes is still debated, but the differences in anatomy most likely have no impact on foot function.

Relationship between the length of the forefoot bones and performance in male sprinters.

Although recent studies have reported that the forefoot bones are longer in sprinters than in non-sprinters, these reports included a relatively small number of subjects. Moreover, while computer simulation suggested that longer forefoot bones may contribute to higher sprint performance by enhancing plantar flexor moment during sprinting, the correlation between forefoot bone length and sprint performance in humans has not been confirmed in observational studies. Thus, using a relatively large sample, we compared the length of the forefoot bones between sprinters and non-sprinters. We also examined the relationship between forefoot bone length and performance in sprinters. The length of forefoot bones of the big and second toes in 36 well-trained male sprinters and 36 male non-sprinters was measured using magnetic resonance imaging. The length of forefoot bones in the big and second toes was significantly longer in sprinters than in non-sprinters. After dividing the sprinters into faster and slower groups according to their personal best time in the 100-m sprint, it was found that the forefoot bone length of the second toe, but not that of the big toe, was significantly longer in faster group than in slower group. Furthermore, the forefoot bone length of the second toe correlated significantly with the personal best time in the 100-m sprint. This study supported evidence that the forefoot bones are longer in sprinters than in non-sprinters. In addition, this is the first study to show that longer forefoot bones may be advantageous for achieving superior sprint performance in humans.

Non-metric variation of the middle phalanges of the human toes (II-V): long/short types and their evolutionary significance.

The human lateral toes are characterised by extreme reduction compared with other primates, and in particular other hominoids. Some phalangeal non-metric variants have been well identified in humans, in particular: triphalangeal/biphalangeal patterns, and the presence/absence of phalangeal secondary centres of ossification. The purpose of the present study was to describe and analyse an original non-metric variation of the middle phalanges of the lateral toes. The material consisted of 2541 foot radiographs that came from 2541 different European adult individuals. Two morphological types of the middle phalanx were defined as a simple binary trait: long type (L) and short type (S). In feet with a triphalangeal pattern in all lateral toes (1413 cases), a mediolateral increasing gradient was observed in the occurrence of type S: 8.1% in II; 30.7% in III; 68.4% in IV; and 99.1% in V. In feet with a biphalangeal pattern in one or more lateral toes (III-V; 1128 cases), type S occurred more frequently than in triphalangeal feet. Of the 30 theoretical arrangements of the L/S types in the lateral toes (II-V) in a complete foot, only 13 patterns were observed. Seven patterns represented 95.6% of the population: LLSS (20.9%), LLLS (17.1%), LSS (15.9%), SSS (14.5%), LSSS (12.7%), LLS (10.1%) and SSSS (4.4%). Type L can be interpreted as the primitive pattern (plesiomorphy), and type S as a derived pattern (apomorphy) that seems specific to the human species (i.e. autapomorphy). Within the specific evolution of the human foot in relation to the acquisition of constant erect posture and bipedalism, the short type of the middle phalanges can reasonably be considered as directly linked to the reduction of the lateral toes.

Side-specific effect of yolk testosterone elevation on second-to-fourth digit ratio in a wild passerine.

Second-to-fourth digit ratio is a widely investigated sexually dimorphic morphological trait in human studies and could reliably indicate the prenatal steroid environment. Conducting manipulative experiments to test this hypothesis comes up against ethical limits in humans. However, oviparous tetrapods may be excellent models to experimentally investigate the effects of prenatal steroids on offspring second-to-fourth digit ratio. In this field study, we injected collared flycatcher (Ficedula albicollis) eggs with physiological doses of testosterone. Fledglings from eggs with elevated yolk testosterone, regardless of their sex, had longer second digits on their left feet than controls, while the fourth digit did not differ between groups. Therefore, second-to-fourth digit ratio was higher in the testosterone-injected group, but only on the left foot. This is the first study which shows experimentally that early testosterone exposure can affect second-to-fourth digit ratio in a wild population of a passerine bird.

Normative data for the American Orthopedic Foot and Ankle Society ankle-hindfoot, midfoot, hallux and lesser toes clinical rating system.

PURPOSE: Despite some theoretical reservations, the AOFAS clinical rating system with its scales for ankle-hindfoot, midfoot, hallux and lesser toes is one of the most widely used assessment tools in foot and ankle surgery. This study was designed to generate age- and gender-related norm values for all four subscales. METHODS: Despite not being used in a self-administered manner, the AOFAS score underwent cross cultural adaptation to guarantee unrestricted comparability of data. A data pool was generated using the results of personal interviews and clinical examination of 625 individuals, including staff and visitors to our hospital, and excluding people scheduled for foot surgery or in after-treatment. These data served as a basis to calculate all four parts of the AOFAS clinical rating system. RESULTS: Mean value for the ankle-hindfoot scale was calculated as 91.6 points (±0.9 confidence interval), and 89.3 points for the midfoot scale (±1.0 CI), 88.3 for the hallux metatarsophalangeal-interphalangeal scale (± 0.9 CI) and 91.0 for the lesser metatarsophalangeal-interphalangeal scale (± 0.8 CI). Results showed a decrease with age in all four scales. Males showed better results than females. Individuals with previous surgery showed lower results in the respective score. CONCLUSIONS: While lowered scoring results prior to surgery reflect the degree of restrictions due to pain, function and alignment problems, post-operative increases in clinical scoring should indicate return to age-related norm values. Our data calculated these norm values for the first time for all four AOFAS scales, giving a basis for better interpretation of published results in foot and ankle surgery. Our data showed and quantified the decrease of norm values with age, especially for hallux and lesser toes scores, as well as lower norm values for females and for individuals that had had surgery of the foot. LEVEL OF EVIDENCE: Level I, diagnostic study.

Towards the resolution of a long-standing evolutionary question: muscle identity and attachments are mainly related to topological position and not to primordium or homeotic identity of digits.

Signaling for limb bone development usually precedes that for muscle development, such that cartilage is generally present before muscle formation. It remains obscure, however, if: (i) tetrapods share a general, predictable spatial correlation between bones and muscles; and, if that is the case, if (ii) such a correlation would reflect an obligatory association between the signaling involved in skeletal and muscle morphogenesis. We address these issues here by using the results of a multidisciplinary analysis of the appendicular muscles of all major tetrapod groups integrating dissections, muscle antibody stainings, regenerative and ontogenetic analyses of fluorescently-labeled (GFP) animals, and studies of non-pentadactyl human limbs related to birth defects. Our synthesis suggests that there is a consistent, surprising anatomical pattern in both normal and abnormal phenotypes, in which the identity and attachments of distal limb muscles are mainly related to the topological position, and not to the developmental primordium (anlage) or even the homeotic identity, of the digits to which they are attached. This synthesis is therefore a starting point towards the resolution of a centuries-old question raised by authors such as Owen about the specific associations between limb bones and muscles. This question has crucial implications for evolutionary and developmental biology, and for human medicine because non-pentadactyly is the most common birth defect in human limbs. In particular, this synthesis paves the way for future developmental experimental and mechanistic studies, which are needed to clarify the processes that may be involved in the elaboration of the anatomical patterns described here, and to specifically test the hypothesis that distal limb muscle identity/attachment is mainly related to digit topology.

Magnetic resonance imaging of the pulleys of the flexor tendons of the toes at 11.7 T.

OBJECTIVE: We obtained high-resolution 11.7-T MR images of the pulleys of the flexor tendons in cadaveric toe specimens. A detailed understanding of toe pulley anatomy as seen with MR is likely to be of benefit in recognizing disease and the effects of trauma. MATERIAL AND METHODS: Six cadaveric toes were imaged with an 11.7-T small-bore MR imaging system using optimized coils. Two-dimensional dual-echo SE scans were obtained in three planes (40 × 40 × 400-µm(3) voxel size, TE = 7/14 ms, TR = 3,500 ms, fat saturation). Three-dimensional spoiled gradient echo scans were obtained (90-150 µm(3) isotropic voxel size, TE = 6 ms, TR = 25 ms, with and without fat saturation). Specimen orientation was with the long axis of the toe either parallel or perpendicular to B0. RESULTS: All the annular (A) pulleys were demonstrated in the great and lesser toes. The A2 pulley in the great and lesser toes and the A4 pulley in the lesser toes were the most substantial pulleys. The A5 pulley, which has not previously been described in the toes, was demonstrated. The cruciform pulleys were also seen and were smaller and thinner. Three tissue layers were seen, and there was evidence of different fiber directions in annular pulleys producing different magic angle effects. CONCLUSION: Detailed anatomy of the pulley system of the flexor tendons was seen on the 11.7-T MR images showing new features and providing a basis for image interpretation. Similarities and differences between the pulley systems in the toes and the fingers were identified.

The effect of toe trimming on behavior, mobility, toe length and other indicators of welfare in tom turkeys.

Society is increasingly concerned about the welfare of animals kept for food production, for this reason, invasive procedures such as toe trimming in turkeys must be studied to assess the corresponding welfare implications and to ensure such procedures are acceptable for continued use. To this end, research was conducted to evaluate the welfare effects of toe trimming on toms raised to 140 d. The study used 306 Hybrid Converter toms, half of which were toe trimmed using a Microwave Claw Processor (MCP) which group are denoted T, and half of which were sham treated but not trimmed, which group are denoted NT. Turkey behavior was observed on d 1, 3, 5, and 133. Toe cross sections were taken every second day for 14 d after treatment and were used to histologically examine the healing process. Toe length, gait score, and bird stance were assessed on d 55, 84, 119, and 139. For the first 5 d after treatment, T birds demonstrated less active behaviors such as feeding, standing, walking and running (P ≤ 0.05), indicative of pain with the effect diminishing with age. At d 133, T turkeys stood more and walked less than NT birds (P ≤ 0.05). Gait score and bird stance were not affected by treatment. Trimmed toes were on average 91.9% of the length of NT toes and toe length was more variable (P ≤ 0.05) as a result of the trimming process. Histological examination indicated T toes had complete epithelium closure over the healthy tissue by d 8 and were fully healed by d 14. Although bird mobility and stance were unaffected by treatment, turkey behavior both early and late in the production cycle were suggestive of pain and balance effects; both indicators of reduced welfare as a result of toe trimming.