Traumatic pericardial rupture with secondary cardiac herniation in a dog.

OBJECTIVE: To describe the unique finding and treatment of a dog with cardiac herniation due to traumatic pericardial rupture. CASE SUMMARY: A 6.5-year-old entire male Yorkshire Terrier was presented for further management after being hit by a car. Despite suspected significant intrathoracic trauma at that time, the patient regained hemodynamic stability and had orthopedic surgery to correct a right iliac fracture. The patient was readmitted to the hospital 12 days following the initial visit due to considerable respiratory difficulty after accidentally being dropped several feet. Thoracic radiographs revealed an unusual severe mediastinal shift to the left with an atypical position of the cardiac silhouette against the left lateral thoracic wall. Due to the severe respiratory compromise of the patient and newly developed pneumothorax, an exploratory thoracotomy was recommended, where a complete rupture of the pericardium was identified, with secondary left-sided prolapse of the heart. Other more common intrathoracic injuries (ie, lung perforation, rib fractures) were also identified and partially repaired. The patient recovered successfully and was discharged 4 days postoperatively. NEW OR UNIQUE INFORMATION PROVIDED: This is the first case report in the veterinary literature of traumatic pericardial rupture and cardiac herniation. According to human case descriptions, this is a rare and often fatal occurrence, which can be significantly challenging to diagnose preoperatively or antemortem. Emergency veterinary clinicians should be aware of this rare but important complication of blunt thoracic trauma. Surgical intervention may be necessary in cases with suspected or confirmed entrapment of great vessels or cardiac chambers, although these abnormalities were not present in this case.

Gastrointestinal signs and a need for nutritional management may persist long term in dogs and cats undergoing resection of the ileocolic junction: 35 cases (2008-2020).

OBJECTIVE: To evaluate the effects of ileocecocolic junction (ICJ) resection on gastrointestinal signs, biochemical parameters, and nutritional variables in dogs and cats. ANIMALS: 20 dogs and 15 cats that underwent ICJ resection between January 2008 and June 2020. PROCEDURES: Medical records of dogs and cats that underwent ICJ resection were reviewed, and clinical signs, laboratory abnormalities, and nutritional information were obtained. Additional follow-up information was obtained by contacting primary care veterinarians or owners. A subset of dogs (n = 6) and cats (2) were evaluated in the hospital via clinical examination, clinicopathologic testing, nutritional testing, and abdominal ultrasound. RESULTS: Twenty dogs and 15 cats underwent resection of the ICJ for treatment of a variety of conditions. Ten of 20 dogs (50%) and 11/15 cats (73%) were reported by their owners to have a good long-term outcome based on the lack of long-term gastrointestinal signs or the ability to control gastrointestinal signs with diet and supplements alone. Despite owner-reported good outcomes, long-term diarrhea, weight loss, and muscle loss were common. Of the 6 dogs evaluated in the hospital, 3/6 (50%) had muscle loss, 2/6 (33%) had low taurine concentrations, and 1 dog each had low cobalamin, folate, 25-hydroxyvitamin D, and ionized calcium. Neither of the 2 cats evaluated in the hospital had nutritional abnormalities identified. CLINICAL RELEVANCE: Owners should be informed of the possibility of long-term gastrointestinal clinical signs and the potential need for long-term nutritional management after ICJ resection.

Outcome and Prognostic Factors in Cats Undergoing Resection of Intestinal Adenocarcinomas: 58 Cases (2008-2020).

The purpose of this multi-institutional retrospective study was to expand the available data pertaining to pre-operative clinical findings, progression-free and overall survival times, and potential prognostic factors for cats undergoing surgery for intestinal adenocarcinomas. Fifty-eight cats treated over a 12-year period were included in the study. Progression-free and overall survival times were estimated using Kaplan-Meier analyses. Potential prognostic variables were evaluated for associations with progression-free and overall survival using univariate Cox proportional hazards regression analyses. Prior to surgery, the intestinal mass was identified using ultrasonography in 89% of cats in which it was applied; however, imaging findings suggestive of intrathoracic metastases were observed in only 9% of cats. Among 22 cats undergoing ultrasound-guided fine needle aspiration cytology, the results agreed with the results of histopathology in only 10 cats. Discordant results were most commonly related to the presence of marked inflammation in cytology samples, which may have obscured the presence of neoplastic cells. Diffuse intestinal small cell lymphoma was identified as a comorbidity in 5 cats. Resection of the tumor with the objective of obtaining wide surgical margins was performed in each cat. On histopathology, 20 tumors were classified as mucinous adenocarcinoma and 28 were adenocarcinoma not otherwise specified. Intestinal transection site margins were complete in 94% of cats; however, complete mural margins were present in only 15% of cats. Local lymph node metastases were identified in 52% of cats and carcinomatosis was diagnosed in 81% of cats. Disease progression was documented in 32 of the 58 cats (55%). Of these 32 cats, 14 (43%) had local recurrence of the primary intestinal tumor. Median progression-free survival was 203 days (95% CI 130-299 days), and median overall survival time was 284 days (95% CI 200-363 days). Mitotic count was inversely associated with progression-free survival (HR 1.04; 95% CI 1.01-1.07, P = 0.005); however, none of the remaining potential prognostic factors, including administration of adjuvant chemotherapy, were significantly associated with progression-free or overall survival. Feline intestinal adenocarcinoma remains an aggressive and highly fatal disease. Large, randomized controlled clinical trials will be needed to improve the survival prospects for affected cats.

Development and validation of a multivariable model and online decision-support calculator to aid in preoperative discrimination of benign from malignant splenic masses in dogs.

OBJECTIVE: To develop a multivariable model and online decision-support calculator to aid in preoperative discrimination of benign from malignant splenic masses in dogs. ANIMALS: 522 dogs that underwent splenectomy because of splenic masses. PROCEDURES: A multivariable model was developed with preoperative clinical data obtained retrospectively from the records of 422 dogs that underwent splenectomy. Inclusion criteria were the availability of complete abdominal ultrasonographic examination images and splenic histologic slides or histology reports for review. Variables considered potentially predictive of splenic malignancy were analyzed. A receiver operating characteristic curve was created for the final multivariable model, and area under the curve was calculated. The model was externally validated with data from 100 dogs that underwent splenectomy subsequent to model development and was used to create an online calculator to estimate probability of splenic malignancy in individual dogs. RESULTS: The final multivariable model contained 8 clinical variables used to estimate splenic malignancy probability: serum total protein concentration, presence (vs absence) of ≥ 2 nRBCs/100 WBCs, ultrasonographically assessed splenic mass diameter, number of liver nodules (0, 1, or ≥ 2), presence (vs absence) of multiple splenic masses or nodules, moderate to marked splenic mass inhomogeneity, moderate to marked abdominal effusion, and mesenteric, omental, or peritoneal nodules. Areas under the receiver operating characteristic curves for the development and validation populations were 0.80 and 0.78, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: The online calculator (T-STAT.net or T-STAT.org) developed in this study can be used as an aid to estimate the probability of malignancy in dogs with splenic masses and has potential to facilitate owners' decisions regarding splenectomy.

Paramedian incisional complications after prophylactic laparoscopy-assisted gastropexy in 411 dogs.

OBJECTIVE: To determine the frequency and types of paramedian incisional complications after prophylactic laparoscopy-assisted gastropexy (LAG) in dogs and to evaluate potential risk factors for complications. STUDY DESIGN: Multi-institutional retrospective study. ANIMALS: Client-owned dogs (N = 411). METHODS: Records for dogs that underwent single-incision-port laparoscopy-assisted gastropexy (SIPLAG) or multiple-port laparoscopy-assisted gastropexy (MPLAG) at five veterinary referral hospitals were reviewed. Information regarding signalment, surgical procedures, perioperative care, and incisional complications was collected. Follow-up information was obtained by review of medical records and/or communication with owners. Potential risk factors for complications were examined statistically. RESULTS: Paramedian incisional complications were observed in 78 of 411 (19%) dogs. The most common complication was seroma formation, which occurred in 51 (12.4%) dogs. Surgical site infections were observed in 16 (3.9%) dogs, and dehiscence or development of excessive scar tissue at the incision site were each observed in nine (2.2%) dogs. Complications resolved with conservative treatment in 75 of 78 (96.2%) dogs and with surgical treatment in three of 78 (3.8%) dogs. The odds of complications were approximately twice as high in dogs undergoing SIPLAG than in dogs undergoing MPLAG (odds ratio, 2.03; P = .006). CONCLUSION: Minor paramedian incisional complications, particularly seroma formation, were frequently observed after LAG. Most complications were successfully managed conservatively. Single-incision-port laparoscopy-assisted gastropexy was associated with a higher complication rate compared with MPLAG. CLINICAL SIGNIFICANCE: Owners should be informed that there is a relatively high rate of minor paramedian incisional complications after LAG. The risk of complications appears to be higher for SIPLAG than for MPLAG.

Postoperative thrombocytosis and thromboelastographic evidence of hypercoagulability in dogs undergoing splenectomy for splenic masses.

OBJECTIVE: To determine the frequency and severity of thrombocytosis and thromboelastographic evidence of hypercoagulability during the first 2 weeks after splenectomy in dogs with splenic masses and to investigate relationships between platelet counts and thromboelastography values. ANIMALS: 34 dogs undergoing splenectomy for splenic masses. PROCEDURES: Blood samples for platelet counts and thromboelastography were obtained at induction of anesthesia (day 0) prior to splenectomy and on days 2, 7, and 14. RESULTS: Mean platelet counts were 167.9 × 103/µL, 260.4 × 103 µ/L, 715.9 × 103/µL, and 582.2 × 103/µL on days 0, 2, 7, and 14, respectively, and were significantly higher at all postoperative assessment points than on day 0. Thrombocytosis was observed in 3% (1/34), 6% (2/33), 81% (21/26), and 69% (18/26) of dogs on days 0, 2, 7, and 14. Platelet counts > 1,000 × 103/µL were observed in 1 dog on day 2 and in 5 dogs on day 7. One or more thromboelastography values suggestive of hypercoagulability were observed in 45% (15/33), 84% (26/31), 89% (24/27), and 84% (21/25) of dogs on days 0, 2, 7, and 14. At each assessment point, higher platelet counts were correlated with thromboelastography values suggestive of hypercoagulability. CONCLUSIONS AND CLINICAL RELEVANCE: Marked thrombocytosis and thromboelastography values suggestive of hypercoagulability were common during the first 2 weeks after splenectomy for the dogs of this study. If present, hypercoagulability could increase the risk for development of postsplenectomy thrombotic conditions such as portal system thrombosis and pulmonary thromboembolism.

Charging of Oxide Nanoparticles in Media of Intermediate Dielectric Constant.

The use of surfactants to charge colloidal particles in solvents of intermediate dielectric constants (5 < ε < 40) is investigated. While particle charging mechanisms in aqueous (ε = 80) and apolar (ε < 5) media are well understood, the interplay of these different charging mechanisms, which can all occur in solvents of intermediate dielectric constants (sometimes referred to as "leaky dielectrics"), remains to be fully explored. Conductometric titrations determining the critical micelle concentration (CMC) of the surfactant (aerosol-OT) confirm the existence of reverse micelles in intermediate dielectrics and show that as the solvent dielectric constant decreases, the CMC decreases as well. Electrophoretic mobility measurements of three oxide particles (SiO2, TiO2, and MgO) highlight various charging mechanisms that arise from particle-solvent, particle-surfactant, and solvent-surfactant interactions in a solvent series of alcohols and ketones. The results show that a combination of donor-acceptor particle-solvent interactions, surfactant ion adsorption, and reverse micelle-mediated acid-base interactions can all charge oxide particles in intermediate dielectrics. Furthermore, the results show that the dielectric constant of the solvent affects the relative magnitudes of each charging mechanism.

Radiographic Differentiation of Cranial Mediastinal Lymphomas from Thymic Epithelial Tumors in Dogs and Cats.

In both dogs and cats, the most common cranial mediastinal masses (CMMs) are lymphoma and thymic epithelial tumors (TETs). Pretreatment differentiation of these tumors using fine needle aspiration or biopsy is essential because lymphomas are treated medically, whereas TETs are treated surgically. The purpose of this retrospective study was to determine whether thoracic radiographic findings can be used to aid clinicians in preliminarily differentiating the two tumor types before cytology or histopathology results become available. Medical records, available cytologic or histologic samples, and thoracic radiographs were evaluated for 62 dogs and 28 cats. Seventeen radiographic criteria were assessed by two examiners, and regression modeling was performed to test for significant predictors of tumor type. In dogs, CMMs with at least two well-defined radiographic margins on a lateral view and CMMs causing a rightward shift of the cardiac silhouette on a ventrodorsal or dorsoventral view were significantly more likely to be TETs than lymphomas (P < .001 and P < .01, respectively). No significant predictive variables were identified in cats. Radiographic findings do not eliminate the need for invasive sampling, but in dogs, they may guide the clinician in providing preliminary information to owners regarding the staging and therapeutic measures that may eventually be recommended.

Histologic evaluation of mandibular and medial retropharyngeal lymph nodes during staging of oral malignant melanoma and squamous cell carcinoma in dogs.

OBJECTIVE: To assess histologic evaluation of mandibular lymph nodes (MLNs) and medial retropharyngeal lymph nodes (MRLNs) for metastatic disease during tumor staging for dogs with oral malignant melanoma (OMM) and oral squamous cell carcinoma (OSCC). DESIGN: Retrospective multi-institutional study. ANIMALS: 27 dogs with OMM and 21 dogs with OSCC. PROCEDURES: Medical record databases of 8 institutions were searched to identify dogs with OMM or OSCC that underwent unilateral or bilateral extirpation of the MLNs and MRLNs during the same procedure between January 2004 and April 2016. Information extracted from the records included signalment, primary mass location and size, diagnostic imaging results, histologic results for the primary tumor and all lymph nodes evaluated, and whether distant metastasis developed. RESULTS: Prevalence of lymph node metastasis did not differ significantly between dogs with OMM (10/27 [37%]) and dogs with OSCC (6/21 [29%]). Distant metastasis was identified in 11 (41%) dogs with OMM and was suspected in 1 dog with OSCC. The MRLN was affected in 13 of 16 dogs with lymph node metastasis, and 3 of those dogs had metastasis to the MRLN without concurrent metastasis to an MLN. Metastasis was identified in lymph nodes contralateral to the primary tumor in 4 of 17 dogs that underwent contralateral lymph node removal. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated histologic evaluation of only 1 MLN was insufficient to definitively rule out lymph node metastasis in dogs with OMM or OSCC; therefore, bilateral lymphadenectomy of the MLN and MRLN lymphocentra is recommended for such dogs.

Perioperative characteristics, histological diagnosis, and outcome in cats undergoing surgical treatment of primary hyperparathyroidism.

OBJECTIVE: To report perioperative characteristics, complications, histopathologic diagnosis and outcome in cats undergoing surgical treatment for primary hyperparathyroidism (PHPT). STUDY DESIGN: Multi-institutional, retrospective case series. ANIMALS: Thirty-two client-owned cats. METHODS: Medical records of cats treated with surgical removal of 1 or more parathyroid gland(s) with confirmed histopathologic evaluation were reviewed. Cats were divided into preoperative ionized calcium (iCa) groups corresponding to the 33rd, 67th, and 100th percentiles of the preoperative iCa results of the study population. Follow-up consisted of phone conversation with owners or primary veterinarian. RESULTS: Ionized calcium was above reference range in all cats (median 1.8 mmol/L [interquartile range, 1.5-1.9]). Abnormal tissue was excised after cervical exploration in all cats. The most common histopathologic diagnoses were parathyroid adenoma in 20 of 32 (62.5%) cats and parathyroid carcinoma in 7 of 32 (21.9%) cats. At discharge, 6 of 32 (18.8%) cats had hypercalcemia, 5 of 32 (15.6%) had hypocalcemia, and 21 of 32 (65.6%) were normocalcemic. Preoperative iCa did not correlate with postoperative iCa. The median follow-up time was 332 days (range, 7-3156). Overall median survival time was 1109 days (95% CI, 856-1332). Survival time was not associated with preoperative iCa group, hypocalcemia at discharge, hypercalcemia at discharge, or diagnosis of carcinoma. CONCLUSION: In this cohort of cats, parathyroid adenoma was the most common cause of PHPT, and surgical treatment resulted in very good median survival time. Preoperative iCa was not predictive of postoperative hypocalcemia. CLINICAL SIGNIFICANCE: Surgical parathyroidectomy for treatment of PHPT in cats provides a favorable prognosis.

Facilitated delignification in CAD deficient transgenic poplar studied by confocal Raman spectroscopy imaging.

Lignocellulosic biomass represents the only renewable carbon resource which is available in sufficient amounts to be considered as an alternative for our fossil-based carbon economy. However, an efficient biochemical conversion of lignocellulosic feedstocks is hindered by the natural recalcitrance of the biomass as a result of a dense network of cellulose, hemicelluloses, and lignin. These polymeric interconnections make a pretreatment of the biomass necessary in order to enhance the susceptibility of the polysaccharides. Here, we report on a detailed analysis of the favourable influence of genetic engineering for two common delignification protocols for lignocellulosic biomass, namely acidic bleaching and soda pulping, on the example of CAD deficient poplar. The altered lignin structure of the transgenic poplar results in a significantly accelerated and more complete lignin removal at lower temperatures and shorter reaction times compared to wildtype poplar. To monitor the induced chemical and structural alterations at the tissue level, confocal Raman spectroscopy imaging, FT-IR spectroscopy, and X-ray diffraction were used.

Socioeconomic inequalities in health during the Great Recession: A scoping review of the research literature.

Aims: The so-called 'Great Recession' in Europe triggered widespread concerns about population health, as reflected by an upsurge in empirical research on the health impacts of the economic crisis. A growing body of empirical studies has also been devoted to socioeconomic inequalities in health during the Great Recession. The aim of the current study is to summarise this health inequality literature by means of a scoping review. Methods: We have performed a scoping review of the research literature (English language) published in the years 2012-2017. Only empirical papers with (a) health status measured on the individual level, (b) information on socioeconomic position (i.e. employment status, educational level, income/wealth, and/or occupational class), and (c) data from European countries in both pre- and post-crisis years were considered relevant. In total, 49 empirical studies fulfilled these inclusion criteria. Results: The empirical findings in the 49 included studies predominantly show that socioeconomic inequalities in health either increased or remained stable from pre- to post-crisis years. Two-thirds (65%) of the studies found evidence of either increasing or partially increasing health inequalities. Thus, people in lower socioeconomic strata fared worse overall in terms of health during the Great Recession, compared to people with higher socioeconomic status. Conclusions: The Great Recession in Europe tends to be followed by increasing socioeconomic inequalities in health. Policymakers should take note of this finding. Widening socioeconomic inequalities in health is a major cause of concern, in particular if health deterioration among 'vulnerable groups' is caused by accelerating cumulative disadvantages.

Tracking of Short Distance Transport Pathways in Biological Tissues by Ultra-Small Nanoparticles.

In this work, ultra-small europium-doped HfO2 nanoparticles were infiltrated into native wood and used as trackers for studying penetrability and diffusion pathways in the hierarchical wood structure. The high electron density, laser induced luminescence, and crystallinity of these particles allowed for a complementary detection of the particles in the cellular tissue. Confocal Raman microscopy and high-resolution synchrotron scanning wide-angle X-ray scattering (WAXS) measurements were used to detect the infiltrated particles in the native wood cell walls. This approach allows for simultaneously obtaining chemical information of the probed biological tissue and the spatial distribution of the integrated particles. The in-depth information about particle distribution in the complex wood structure can be used for revealing transport pathways in plant tissues, but also for gaining better understanding of modification treatments of plant scaffolds aiming at novel functionalized materials.

Heart rate reactivity to trauma-related imagery as a measure of PTSD symptom severity: Examining a new cohort of Veterans.

For over three decades, there has been considerable research documenting increased physiological reactivity to trauma-related stimuli as a characteristic feature of posttraumatic stress disorder (PTSD). The present study explored the potential for physiological assessment to aid in defining and validating screening criteria for the presence of significant PTSD-related symptoms in a sample of OEF/OIF/OND Veterans seeking care in a VA post-deployment health clinic. Heart rate reactivity scores during the imagining phase of the script-driven imagery paradigm were compared across groups of individuals with and without probable PTSD diagnoses, as defined by PCL-IV cutoff scores ranging from 40 to 60. Significant differences were found for groups defined by PCL-IV cutoff scores of 50 and 60, with 50 producing the largest effect size. Diagnosing PTSD is made challenging by the presence of overlapping symptoms shared with other diagnoses, as well as by the necessity for patients to accurately report their symptoms. An objective physiological measure capable of accurately differentiating individuals with and without PTSD provides potential adjunctive diagnostic and treatment information to clinicians. The present findings support the validity of physiological reactivity during SDI as a NIMH RDoC measure that can be used in research and clinical applications assessing trauma-related symptom severity.

Synthesis and Characterization of the Actinium Aquo Ion.

Metal aquo ions occupy central roles in all equilibria that define metal complexation in natural environments. These complexes are used to establish thermodynamic metrics (i.e., stability constants) for predicting metal binding, which are essential for defining critical parameters associated with aqueous speciation, metal chelation, in vivo transport, and so on. As such, establishing the fundamental chemistry of the actinium(III) aquo ion (Ac-aquo ion, Ac(H2O) x3+) is critical for current efforts to develop 225Ac [t1/2 = 10.0(1) d] as a targeted anticancer therapeutic agent. However, given the limited amount of actinium available for study and its high radioactivity, many aspects of actinium chemistry remain poorly defined. We overcame these challenges using the longer-lived 227Ac [t1/2 = 21.772(3) y] isotope and report the first characterization of this fundamentally important Ac-aquo coordination complex. Our X-ray absorption fine structure study revealed 10.9 ± 0.5 water molecules directly coordinated to the AcIII cation with an Ac-OH2O distance of 2.63(1) Å. This experimentally determined distance was consistent with molecular dynamics density functional theory results that showed (over the course of 8 ps) that AcIII was coordinated by 9 water molecules with Ac-OH2O distances ranging from 2.61 to 2.76 Å. The data is presented in the context of other actinide(III) and lanthanide(III) aquo ions characterized by XAFS and highlights the uniqueness of the large AcIII coordination numbers and long Ac-OH2O bond distances.

Photophysical Dynamics and Relaxation Pathways of Ligand-to-Metal Charge-Transfer States in the 5f1 [Np(VI)O2Cl4]2- Anion.

Although several publications report on the electronic structure of the neptunyl ion, experimental measurements to detail the photophysical dynamics of this open-shell actinyl system are limited in number. Time-resolved photoluminescence has been a useful experimental approach for understanding photophysical dynamics and relaxation pathways of a variety of other molecular and ionic systems, including gaseous plutonium hexafluoride and solid-state uranyl compounds. Here, we investigate time-resolved photoluminescence emission of the 5f1 neptunyl tetrachloride ([Np(VI)O2Cl4]2-) dianion following visible excitation. Photoemission of the lowest energy neptunyl ligand-to-metal charge-transfer (LMCT) transitions to both the ground and first electronically excited states is observed. Analyses of the decay lifetimes of the excited states suggest different relaxation pathways as a function of excitation energy. Vibronic progressions associated with the Np-oxo symmetric stretching mode are measured in emission spectra, and the energies from these progressions are compared with energies of vibronic progressions associated with the excitation spectra of [Np(VI)O2Cl4]2-. This study expands our understanding of this open-shell actinyl system beyond identification of excited states, allowing characterization of photophysical properties and evidence for the electronic character of the ground state, and suggests that this approach may be applicable to more complex actinide systems.

Effects of Reverse Micellar Structure on the Particle Charging Capabilities of the Span Surfactant Series.

This paper investigates the effects of reverse micellar core size on the particle charging behavior of a series of acidic surfactants in apolar media. A series of Span surfactants was dissolved in deuterated decane at concentrations above the critical micelle concentration. The structures of the reverse micelles were measured using small-angle neutron scattering. It was determined that as the tail length of the surfactant increased, the size of the polar reverse micellar core decreased. Tritailed surfactants formed reverse micelles with the smallest polar cores, with radii of ∼4 Å. The sizes of the polar cores were correlated with the particle charging behavior of the Span surfactant series, as measured in a previous study. It was found that reverse micelles with intermediate core sizes imparted the largest electrophoretic mobilities to the particles. Reverse micelles with very small cores did not offer a large enough polar environment to favor charge stabilization, while very large polar cores favored disproportionation reactions in the bulk, resulting in increased electrostatic screening.

Spectroscopic and computational investigation of actinium coordination chemistry.

Actinium-225 is a promising isotope for targeted-α therapy. Unfortunately, progress in developing chelators for medicinal applications has been hindered by a limited understanding of actinium chemistry. This knowledge gap is primarily associated with handling actinium, as it is highly radioactive and in short supply. Hence, Ac(III) reactivity is often inferred from the lanthanides and minor actinides (that is, Am, Cm), with limited success. Here we overcome these challenges and characterize actinium in HCl solutions using X-ray absorption spectroscopy and molecular dynamics density functional theory. The Ac-Cl and Ac-OH2O distances are measured to be 2.95(3) and 2.59(3) Å, respectively. The X-ray absorption spectroscopy comparisons between Ac(III) and Am(III) in HCl solutions indicate Ac(III) coordinates more inner-sphere Cl(1-) ligands (3.2±1.1) than Am(III) (0.8±0.3). These results imply diverse reactivity for the +3 actinides and highlight the unexpected and unique Ac(III) chemical behaviour.