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Background: The survival of horses diagnosed with critical colic (requiring referral or euthanasia) relies on rapid and effective decision-making by the owner and veterinary practitioner., Objectives: To explore UK horse owners' and veterinary practitioners' experiences of decision-making for critical cases of equine colic., Study Design: Qualitative study using a phenomenological approach., Methods: Individual, semi-structured telephone interviews were conducted with 14 horse owners and 13 veterinary practitioners (vets) who had experienced a critical decision (referral or euthanasia) for a horse with colic. A purposive, convenience sample of participants was recruited. Sessions explored participant's experience of colic, including recognition, help-seeking behaviour, and challenges. Thematic analysis was performed on collected data., Results: Four over-arching themes were identified; 'head', 'heart', 'practicalities' and 'impact'. Owners acknowledged responsibility for their horse's welfare but had different perspectives than vets on the importance of finance ('head'). Both vets and owners described how the horse-human relationship ('heart') often led to conflict during decision-making. The vet-client relationship was influential on decision-making for both owners and vets; involving other people in decision-making was described both positively and negatively by participants ('heart'). 'Practicalities', such as lack of preparedness, transport issues and adverse weather conditions, were identified by both owners and vets as barriers. Owners described a 'rollercoaster' of emotions after a critical decision, with profound impacts on their mental wellbeing, feelings of guilt, and long-term changes in behaviour ('impact'), and a lack of support to manage these feelings., Main Limitations: Small sample size., Conclusions: This study describes stakeholder decision-making during critical cases of equine colic. Factors that commonly influenced decisions included an owner's previous knowledge and beliefs, social pressures, logistics and the relationship between the owner and vet. The study highlighted long-term impacts on the owner, including their management and decisions for subsequent horses. These factors should be considered in shared decision-making., (© 2024 The Author(s). Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.)

Background: As a major animal control service provider in the city of Guelph and Wellington County in Ontario, the Guelph Humane Society transports and presents injured or ill raccoons requiring humane euthanasia to the Ontario Veterinary College Health Sciences Centre (OVC-HSC). Issues around handling, transportation, and delays before euthanasia have recently raised some concerns for welfare and the need for means of improving this process., Objective: Investigation of a noncontrolled sedation and analgesia protocol for injured or ill raccoons intended to improve animal welfare by allowing humane handling, transport, and euthanasia following administration by an animal protection officer (APO)., Animals and Procedure: Twenty-seven injured or ill raccoons requiring transport and euthanasia, as determined by the Guelph Humane Society APOs, were included in the study. Each raccoon was administered acepromazine (0.05 mg/kg), alfaxalone (4 mg/kg), and medetomidine (0.15 mg/kg), intramuscularly, before being transported to the OVC-HSC for humane euthanasia., Results: The combination of acepromazine, alfaxalone, and medetomidine was suitable for administration by APOs and provided the desired sedation depth to allow transport and humane euthanasia. Transit time was the only predictor of sedation depth upon arrival at the OVC-HSC. Two raccoons showed mild physical response to intracardiac injection for euthanasia. Numerical cutoff points of an in-hospital visual analog score of sedation of ≥ 70/100 and duration of sedation of < 62 min showed zero probability of response to euthanasia., Conclusion and Clinical Relevance: Administration of acepromazine, alfaxalone, and medetomidine at the stated doses provided acceptable sedation and analgesia to improve animal welfare during transport and eventual euthanasia of raccoons., (Copyright and/or publishing rights held by the Canadian Veterinary Medical Association.)

Euthanasia agents should rapidly induce death and loss of consciousness without causing pain or distress. Various methods exist for the euthanasia of laboratory animals, and injectable anesthetics, particularly barbiturate derivatives, are widely used due to the rapid onset of unconsciousness induced by these agents. Moreover, pharmaceutical-grade drugs should be used to eliminate undesirable side effects as much as possible. However, in Japan, the sale of pharmaceutical-grade pentobarbital sodium (PB) ended in 2019, and that of secobarbital sodium (SB) ended in 2023, leading to a demand for new pharmaceutical-grade injectable euthanasia drugs. This study evaluates thiamylal sodium (TM), a barbiturate derivative that is available domestically, as a euthanasia agent for mice. The results showed that when administered at dosages of 200 mg/kg or more, TM exhibited effects equivalent to those of PB and SB. In addition, the impact of TM administration on hematological characteristics was examined. In female mice administered TM, decreased blood chloride and calcium levels and increased aspartate aminotransferase and alanine aminotransferase levels, which are markers of liver damage, were observed. These findings suggest that high concentrations of TM may affect renal and liver function. This study revealed that TM is effective as a euthanasia agent at dosages of 200 mg/kg or more. However, considering the potential risks of renal and liver damage due to TM administration, it may be preferable to use alternative euthanasia drugs when these risks could affect the objectives or outcomes of the research.

Objective: To provide a video tutorial describing intraperitoneal (IP) and intracoelomic (IC) therapeutics (IP/IC fluid therapy, euthanasia, direct peritoneal resuscitation)., Animals: Dogs, cats, and exotic pets., Methods: Peritoneal and coelomic centesis allows for delivery of fluids or to perform euthanasia. The peritoneal and coelomic membranes contain a vast network of capillaries and lymphatics that allow absorption of fluids and blood products. Needles are inserted aseptically IP or IC at species-specific locations to avoid iatrogenic damage. In mammals, the needle is inserted in a periumbilical location at a 1- to 2-cm radius from the umbilicus, while the needle is inserted into the ventral inguinal fossa in chelonians and lateroventrally in lizards and snakes. Direct peritoneal resuscitation is a human technique in which a dextrose/electrolyte solution infused IP reduces ischemia-reperfusion injury, edema, and tissue necrosis to improve mortality in patients with diseases like shock and sepsis or who require acute abdominal surgery., Results: Isotonic crystalloids are given IP/IC at 10- to 20-mL/kg doses (smaller volumes in reptiles) and blood products at standard calculated doses. Sodium pentobarbital without phenytoin (3 mL/4.5 kg) is used for IP/IC euthanasia., Clinical Relevance: Being aware of multiple routes for fluid and blood product administration allows treatment in animals for which intravenous or intraosseous catheterization is undesirable or impossible. While intravenous or intraosseous routes are always preferred, especially for resuscitation, familiarity with locations for IP/IC fluid and euthanasia is useful. Techniques like direct peritoneal resuscitation are not currently used in animals but might be translated to veterinary cases in the future.

Climate change has been one of the most discussed topics in the world. Global warming is characterized by an increase in global temperature, also in aquatic environments. The increased temperature can affect aquatic organisms with lethal and sublethal effects. Thus, it is necessary to understand how different species respond to temperature. This study aimed to evaluate how the Neotropical catfish species Rhamdia quelen responds to temperature increases. The fish were exposed to temperatures of 25 °C (control) and 30 °C after gradual temperature increase for 7 days. After 96 h in each temperature, the fish were anesthetized, blood was collected, and after euthanasia, brain, liver, posterior kidney, gills, muscle, and gonads were collected. The gonads were used for sexing, while other tissues were used for the hematological, biochemical, genotoxic, and histopathological biomarkers analysis. Hepatic proteomic analysis with a focus on energy production was also carried out. Blood parameter changes in both sexes, including an increase in glucose in males, leukopenia in females, and genotoxicity in both sexes. Hepatic proteins related to energy production were altered in both sexes, but mainly in males. Others biomarker alterations, such as histopathological, were not observed in other tissues; however, the antioxidant system was affected differently between sexes. These showed that R. quelen juveniles, at temperatures higher than its optimum temperature such as 30 °C, has several sublethal changes, such as hematological alterations, antioxidant system activation, and energetic metabolism alteration, especially in males. Thus, short-term temperature rise can affect females and males of R. quelen differently., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

A 6-year-old spayed female American bulldog was brought to a veterinary clinic with a 3-day history of vomiting, lethargy, anorexia, icterus, hemorrhagic diarrhea, and oliguria. The dog's clinical signs, complete blood (cell) count, serum biochemistry, urinalysis, and diagnostic imaging were indicative of acute kidney injury and acute hepatopathy consistent with leptospirosis. Treatment for leptospirosis was initiated but, due to the dog's lack of response and progression of clinical signs, euthanasia was ultimately elected after 3 d of hospitalization. The dog tested negative for Leptospira spp. on ELISA; urine, blood, and tissue PCRs; and immunohistochemistry. This case demonstrates that confirmation of leptospirosis can be challenging, even in an animal with the expected clinical presentation. Therefore, limitations of the diagnostic tests available, as well as the possibility of other, less likely differential diagnoses such as toxicosis, must be considered., (Copyright and/or publishing rights held by the Canadian Veterinary Medical Association.)

Background: Clients want to know the ultimate cause of death in their pet after cancer treatment. The cause of euthanasia and investigation of urinary obstruction in treated dogs with urothelial carcinoma (UC) has not been specifically reported in veterinary literature., Hypothesis/objectives: Our hypothesis was that the majority of treated dogs with UC are euthanized secondary to primary tumor factors, such as urinary obstruction., Animals: Fifty-nine client-owned dogs diagnosed with UC., Methods: Retrospective observational study on clinical signs and disease at euthanasia of dogs with UC treated by radiation therapy or chemotherapy or both., Results: The median overall survival time (OST) of all dogs was 339 days (range, 17-1996; 95% confidence interval [CI], 185-392; interquartile range [IQR], 112-505). Of dogs deemed to have been euthanized because of UC (50/59, 85%), the primary cause was considered to be local progression in 31/50 (62%), most often because of perceived complete or partial urinary obstruction (24/31, 77%). No variables were found to be predictive of urinary obstruction. The overall documented metastatic rate was 56%. In dogs euthanized because of UC, metastasis was deemed to be the cause in 19/50 (38%) dogs., Conclusions and Clinical Importance: Regardless of the type of treatment, UC in dogs has a poor prognosis and there is a continuing need to improve treatments that focus on local control of the primary tumor, given its high contribution to the decision for euthanasia. Proactive management to avoid the high frequency of urinary obstruction may be worthy of future investigation., (© 2024 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)

Background: Canine cognitive dysfunction (CCD) is a neurodegenerative disease that is difficult to diagnose, as its clinical signs are similar to those of other age-related conditions. The experience of caring for a senior dog with or without CCD is not well described., Methods: Data were collected via an online survey. Using a mixed methods design, the level of CCD and burden of care were measured using validated tools, and open-ended questions gathered qualitative data. A general linear model showed the factors associated with guardian burden of care., Results: Sixteen percent of guardians experienced a clinically significant burden of care. Factors associated with burden of care included severity of CCD, sleep location, guardian employment, household size, dog age, guardian age and the dog taking medication. Few dogs with CCD were prescribed CCD medications to ameliorate clinical signs. Euthanasia, strong attachment mitigating burden and the complexities of caregiving were themes presented by guardians., Limitations: Measures are based on self-reports and as such the usual limitations apply., Conclusions: The burden of caring for an older dog is greater if they have CCD. More attention to the treatment of senior dogs, including medications to reduce clinical signs of CCD, could improve the welfare of older dogs and decrease the clinical burden experienced by guardians., (© 2023 The Authors. Veterinary Record published by John Wiley & Sons Ltd on behalf of British Veterinary Association.)

Feral swine are a highly destructive invasive species around the globe. Wildlife managers commonly trap and euthanize feral swine with firearms to reduce their adverse impacts. The utility of euthanizing domestic swine with firearms has been considered when emergency situations arise such as in the event of a foreign animal disease outbreak in domestic swine. Similarly, the rapid depopulation of domestic swine facilities became necessary when the COVID-19 pandemic disrupted pork production in 2020. Evaluation of the effects of caliber, cartridge, size of feral swine, and shot placement on effectiveness and safety of the method is needed. We collected data from feral swine euthanized in traps on how those variables influenced the effectiveness in time to death and number of shots required and safety risks based on the occurrence of bullet pass-through (i.e., bullet exiting the pig). We tested 3 cartridges of 2 calibers (0.22 long rifle, 0.22 Winchester magnum rimfire, and 0.308 Winchester) delivered from a rifle with 3 shot placements targeting the brain. From 570 euthanization events, we calculated an average time to death of 100.06 (SD = 29.24) s, with larger feral swine taking slightly longer. Most feral swine (73%) were euthanized with a single shot but averaged 1.28 (SD = 0.48) shots overall. Safety risks from pass-through shots were more common when using the 0.308 Winchester cartridge, and when rear and side shot placements were used. Overall, we recommend a 0.22 long rifle cartridge and frontal shot placement as an effective and safe option for euthanizing feral swine in traps, and likely for domestic swine of similar size and shot distances., (Published by Oxford University Press on behalf of the American Society of Animal Science 2024.)

This research explores connections between the nature of a community, the type of animal shelter it has, how animals arrive at the shelter, and outcomes for the animals in terms of adoption or euthanasia. Based on data from Shelter Animals Count, the study concludes that the nature of the local community is related to the type of shelter it is served by, how dogs arrive at the shelter, and directly to outcomes. Areas with greater economic stress and lower educational attainment are more likely to have a municipal shelter, which increases stray intake, and ultimately euthanasia. Community economic stress is also directly associated with lower adoption and higher euthanasia rates. The findings of the study suggest a multi-pronged strategy to increase adoptions and reduce euthanasia focusing on both animal shelters but also using a One Health approach to improve the welfare of both humans and non-human animals.

Blood extraction is extremely important for the development of scientific research; however, the existing methods for amphibian´s blood sampling are invasive, mainly leading to the euthanasia of the animal. Therefore, less intrusive methods that allow the obtention of multiple samples from the same individual, are needed as an alternative to the common methods available. Hence, the aim of this study was to propose a minimally invasive method for obtaining blood from the hind leg of Xenopus laevis , that allows continuous sampling without compromising the wellbeing of the organisms. With this method, it was possible to extract blood and plasma from adults and juveniles, and the amount of sample was enough to perform biochemical and molecular assays to assess the viability of the blood. The results also revealed that this method is a convenient alternative to obtain blood without affecting the welfare of the experimental organisms, avoiding the cull of the animals, and the samples are viable for their use in follow up studies.

Background: French bulldogs hospitalised for the management of intervertebral disc extrusion (IVDE) are frequently affected by respiratory compromise, typically brachycephalic-associated upper respiratory obstruction and/or aspiration events. We evaluated the occurrence of such respiratory compromise events in French bulldogs presented to two referral hospitals., Methods: Clinical data for French bulldogs diagnosed with IVDE were retrospectively collated, including severity of neurological deficits, neuroanatomical localisation, diagnosis, details of respiratory compromise, treatment and outcome., Results: A total of 306 dogs diagnosed with IVDE were included. Sixty dogs (19.6%) experienced respiratory compromise, of which 31 dogs (10.1%) progressed to cyanosis, collapse or respiratory arrest., Limitations: The study was limited by its retrospective nature. Furthermore, the duration of hospitalisation was not evaluated and the decision for euthanasia was often multifactorial., Conclusion: One in five French bulldogs presented with IVDE experienced respiratory compromise. The detrimental welfare effects of this warrant further discussion., (© 2023 The Authors. Veterinary Record published by John Wiley & Sons Ltd on behalf of British Veterinary Association.)

ABSTRACT OBJECTIVE Estimate the coverage of control measures of visceral leishmaniasis and relate them with the occurrence of human visceral leishmaniasis in endemic urban area. METHODS Cases of human and canine visceral leishmaniasis were considered as study population and evaluated by a serological survey conducted in Araçatuba, state São Paulo, from 2007 to 2015. The cases of human visceral leishmaniasis were geocoded by the address of the patients and the canine disease by the address of the dogs’ owners. The coverage of serological survey, euthanasia, and insecticide spraying was calculated, as well as the canine seroprevalence and the incidence rates of human visceral leishmaniasis. The relationship between human visceral leishmaniasis and control measures was evaluated, as well as the seroprevalence by comparing maps and by linear regression. The relationship between the canine and the human disease was also evaluated by the Ripley’s K function. RESULTS The incidence rates of human visceral leishmaniasis showed a period of decline (2007 to 2009) and a period of stability (2010 to 2015), a behavior similar to that of canine seroprevalence. In general, the coverage of control measures was low, and the non-association with the incidence of human visceral leishmaniasis can be a result of the period analyzed and of the small number of analyzed units (sectors of the Superintendence for the Control of Endemic Diseases). The distribution of human cases showed spatial dependence with the distribution of seropositive dogs from 2007 to 2009. CONCLUSIONS This study reaffirmed the relationship between the occurrence of the disease in humans and dogs, it verified a decrease in the rates of visceral leishmaniasis in Araçatuba over time, even at low coverage of control activities. However, further studies are needed to determine if factors beyond monitoring and control measures are involved in the reduction of incidences.

Training personnel to work with animals presents a variety of challenges, both logistically and with regard to animal welfare. These issues make training an ideal opportunity to evaluate practices and to implement the 3R principles (refinement, replacement, and reduction). Cardiac blood collection from mice is a procedure that can compromise the 3Rs by requiring repeated practice and animal euthanasia. The development of a non-animal training model would promote the 3R principles. Our goals for the development of a new training model for cardiac blood collection from mice were to reduce the number of mice needed to achieve competency, improve our culture of care, and refine the training approach by improving competency. The training model was developed using commonly available materials. The total cost of the model was less than $15 USD per model. Two training curricula were conducted concurrently over a 5-mo period: 1) a curriculum in which trainees used the model before progressing to live mice and 2) the traditional curriculum, which used euthanized mice throughout. The measured variables included the total number of mice used, proportions of trainees who reached competency, the time needed to reach competency, method comprehension, quality of skill performance, trainer and trainee feedback, and training costs. The alternative group used at least 10 fewer mice per technician as compared with the traditionally trained group. The alternative group had a higher competency rate, with 82% (9 of 11 trainees) reaching competency compared with 60% (3 of 5 trainees) in the traditional group. Skill comprehension and quality were superior in the alternative group, as evidenced by fewer gross lesions at necropsy. Overall, personnel in the alternative group provided positive feedback with regard to the use of fewer mice, acquisition of both skill and confidence, and benefits for compassion fatigue. The use of this model is now our standard approach for training personnel in cardiac blood collection in mice. Our results demonstrate that the use of models in training curricula can enhance skill development and reduce the use of mice.

Patellar luxation (PL) is a common orthopaedic condition in dogs. This study aimed to evaluate the incidence and cause-specific mortality rate, age at diagnosis, and risk factors for medial PL (MPL), lateral PL (LPL), and bidirectional PL (BPL). Other diagnoses in dogs with PL were also explored. The study population included just over 600,000 dogs insured by Agria Pet Insurance in Sweden (2011-2016). There were 2726 dogs with PL. Medial patellar luxation affected 90 % of the dogs with PL, followed by LPL (5.9 %), BPL (2.4 %), and unspecified PL (1.6 %). The median age at first diagnosis during the study period was 2.8 years for MPL, 2.7 years for LPL, and 1.5 years for BPL. In total, 168 (6.2 %) of the dogs with PL had cruciate ligament rupture. There were substantial breed-specific differences in the risk of PL: almost all breeds at increased risk of MPL were small-sized, while several of the breeds at increased risk of LPL were large-sized. The breeds at high risk of BPL varied in size. Females had an increased risk of MPL (RR 1.2, 95 % CI: 1.1-1.3, p < 0.001) and a decreased risk of LPL (RR 0.72, 95 % CI: 0.51-1.0, p = 0.042) compared to males. In total, 116 dogs were euthanised due to PL and the breeds with the highest risk of PL-related euthanasia were the Pyrenean mountain dog, Dogue de Bordeaux, and German pinscher. The median age for PL-related euthanasia was 2.2 years., Competing Interests: Declaration of Competing Interest The Ph.D. project of the corresponding author (KE) was financed by Agria Pet Insurance Research Foundation in Sweden. JH has received payment from the Swedish Veterinary Association, VeTa bolaget, and Distriktsveterinärerna, for activities unrelated to this manuscript. No other financial support for the research, authorship and/or publication of this article was received. AB and OH declare no potential conflicts of interest., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: Anatomic anomalies in the ascending aorta may impair the implantation and testing of cardiovascular devices in humans and animal models., Case Presentation: We present the rare case of an intra-aortic band in a German Landrace pig. During terminal animal testing, the band hindered the implantation of a left ventricular assist device (LVAD) with transventricular outflow graft across the aortic valve. After lower partial sternotomy, epicardial echocardiography displayed an intraluminal echogenic structure at the sinotubular junction causing unspecific flow turbulences. Under cardiopulmonary bypass, coring of the left ventricular apex was performed. Due to strong resistance in the proximal aorta, accurate positioning of the transventricular LVAD outflow graft was impossible. After euthanasia, necropsy revealed a fibrous band located at the sinotubular junction, dividing the lumen of the ascending aorta., Conclusions: The occurrence of an intra-aortic band represents an extremely rare case of a most likely congenital anomaly. Awareness of such anomalies is important for planning and performing animal testing. Perioperative echocardiography may help to either remove such anomalies or allow discontinuing the procedure prior to device implantation., (© 2023. BioMed Central Ltd., part of Springer Nature.)

Objective: The Dog Aging Project End of Life Survey was used to evaluate factors associated with manner of death (euthanasia vs unassisted death), including cause of death (CoD), reason for euthanasia (RFE) if performed, medical symptoms, old age characteristics, and perimortem quality of life (QoL)., Sample: Responses collected between the End of Life Survey launch (January 20, 2021) through December 31, 2021, from 2,570 participants whose dogs died., Methods: Response frequencies were described. Associations between manner of death and medical symptoms or old age characteristics were evaluated using logistic regression. Factors associated with RFE were evaluated using multinomial regression. The effects of CoD, age at death, and QoL on the frequency of euthanasia as the manner of death were evaluated using multivariate logistic regression., Results: 2,195 (85.4%) dogs were euthanized, and 375 (14.6%) experienced unassisted death. The most frequent owner-reported CoD was illness/disease (n = 1,495 [58.1%]). The most frequently reported RFE was pain/suffering (n = 1,080 [49.2% of those euthanized]). As age increased, RFE was more likely to be "poor QoL" than any other response. In a multivariate regression including CoD, chronologic age, and QoL, euthanasia as the manner of death was not significantly associated with age., Clinical Relevance: Euthanasia was a common manner of death for dogs in the US. Compared with unassisted death, euthanasia was associated with CoD illness/disease, lower QoL scores, and the presence and number of medical symptoms and old age characteristics. Understanding factors associated with manner of death is important to veterinarians who care for dogs at the end of life.

Objective: To describe the knowledge, attitudes, and practices (KAP) towards COVID-19 of Canadian companion animal health workers (AHW); to measure their perceived stress and quality of life (QoL); and to explore professional risk factors associated with stress and QoL., Sample: We sampled 436 companion animal veterinarians and technicians., Procedure: The study had cross-sectional and cohort components. It was conducted online in August to December 2020, and repeated in May to July 2021, using a questionnaire assessing the respondents' professional characteristics, COVID-19 KAP, perceived stress, and QoL., Results: Overall, AHW had sufficient knowledge of COVID-19 transmission, and reported having adopted good preventive practices. Since the beginning of the pandemic, participants reported increases in new clients (76%), in refusal of new clients (53%), and in pet euthanasia (24%). Increased client refusal and pet euthanasia were associated with greater stress and poorer professional QoL, whereas perceived susceptibility to and adoption of measures against COVID-19 were associated with lower stress and better QoL., Conclusion and Clinical Relevance: For AHW, professional characteristics were associated with stress and professional QoL. This information is important for developing strategies to cope with the ongoing shortage of AHW and with future public health crises., (Copyright and/or publishing rights held by the Canadian Veterinary Medical Association.)

Magnesium chloride in high concentration is used for euthanasia of jellyfish to limit overpopulation and for predatory species consumption, but its use could lead to magnesium bioaccumulation and subsequent negative effects in consumers. Two species of scyphozoan jellyfish (Cassiopea andromeda and Aurelia aurita) were subjected to freezing (control), or magnesium chloride baths (144 g/L), with subsequent 30 min baths (one or two) in fresh artificial saltwater and submitted for inductively coupled plasma analysis to determine tissue concentration. Frozen jellyfish consistently yielded the lowest magnesium concentrations, while magnesium chloride euthanized individuals contained the highest concentrations in both species. C. andromeda displayed a significantly higher (p < .05) magnesium absorption capacity than A. aurita in both trials. Single and double baths significantly decreased magnesium concentrations (p < .05) in both species, however, magnesium remained consistently elevated compared to frozen specimens. This study demonstrated species-specific magnesium accumulation in jellyfish posteuthanasia and that rinsing was an effective method to limit excessive magnesium that could be deleterious to animals in public display aquaria. Magnesium concentrations of tissue and receiving water should be tested if magnesium chloride euthanasia is utilized for dietary supplementation in small bodies of water., (© 2023 The Authors. Zoo Biology published by Wiley Periodicals LLC.)

Many dogs and cats were euthanized in US animal shelters through the 1940s, sharply declining in the 1980s. Early age neutering of young cats and dogs grew frequent in the 1990s; adoptions from shelters increased, leading to a decline in shelter euthanasia of dogs. Several publications, beginning in 2013, revealed heightened risks of joint disorders and some cancers for some dog breeds when neutered at young ages. These risks are breed-, gender-, and body-size specific and related to neutering age. Current guidelines suggest making a personalized decision for each dog's neutering age. Recommendations are presented for 40 breeds and mixed-breed weight classes., Competing Interests: Disclosure The authors have nothing to disclose., (Copyright © 2023 Elsevier Inc. All rights reserved.)

This study compared euthanasia induced by rising concentrations of CO₂ in aged rats (n = 59) using different gas displacement rates. Rats were preimplanted with cardiovascular telemetry devices and had been previously used for short term safety pharmacology studies. Once fully recovered from previous studies, rats were euthanized using rising concentrations of CO₂. Three groups were exposed to gas displacement at fixed flow rates of 30%, 40%, and 50%, and 3 groups were exposed to increased flow rates at predetermined, one-minute intervals (10 to 30%, 20 to 40%, and 30 to 50%). Comparisons were based on the time taken to reach 4 critical endpoints: dyspnea, ataxia, recumbency, and death. The preimplanted telemetry devices were used to record cardiovascular parameters. Video recordings of the euthanasias were performed to allow behavioral assessment by a blind observer. The histologic effects of the different concentrations were also evaluated. No significant differences were detected between the groups in behavioral scores or histopathology. Groups of rats exposed to higher levels of CO₂ had a shorter time to loss of consciousness and death than did rats exposed to lower concentrations of CO₂. No statistically significant differences were detected in the time by which rats showed visual signs of dyspnea. Slow CO₂ displacement rates of CO2 may prolong the time necessary for euthanasia yet provide no appreciable improvement in welfare in aged rats and should therefore be avoided.