Cardiovascular changes, laboratory findings and pain scores in calves undergoing ultrasonography-guided bilateral rectus sheath block before herniorrhaphy: a prospective randomized clinical trial.

BACKGROUND: The study aimed to assess the clinical utility of a multiparametric approach to measure the impact of bilateral ultrasound-guided rectus sheath blocks (RSB) on heart rate, serum cortisol concentrations, and pain in calves undergoing herniorraphy. Fourteen calves were randomly assigned to receive either the RSB (RSB group, n = 7, injected with 0.3 mL/kg of bupivacaine 0.25% and 0.15 µg/kg of dexmedetomidine per side) or a sham injection (CG group, n = 7, injected with an equivalent volume of sterile saline solution). Monitoring included (i) continuous Holter recording from 120 min pre-surgery to 120 min post-surgery; (ii) serum cortisol concentration (SC) at -150 min pre-surgery (baseline), induction time, skin incision, end of surgical procedure (EP-t), and then 30 min, 45 min, 60 min, 120 min, 360 min after recovery; (iii) UNESP-Botucatu pain evaluation at -150 min pre-surgery and 30 min, 45 min, 60 min, 120 min, 240 min, 360 min after recovery. RESULTS: A significant difference in the heart rate was observed within the RSB group, in the time frame between 120 min to induction compared to the time frame between induction to EP-t period. The SC concentration was significantly higher in the CG at the skin incision. Calves in the RSB group recorded significantly lower pain scores at 45 min, 60 min, 120 and 240 min after recovery. CONCLUSIONS: The study demonstrated that monitoring heart rate and serum cortisol concentrations effectively quantified the effects of RSB during surgery. At the same time, the UNESP-Botucatu pain scale identified effects post-surgery when the calves regained consciousness. Overall, ultrasound-guided RSB appeared to enhance the well-being of calves undergoing herniorrhaphy.

Clinical efficacy of an ultrasound-guided bilateral rectus sheath block for umbilical hernia repair in calves: A prospective randomized trial.

Introduction: Surgical umbilical hernia repair is a frequent procedure in newborn calves, requiring mandatory pain management. This study aimed to develop an ultrasound-guided rectus sheath block (RSB) and to evaluate its clinical efficacy in calves undergoing umbilical herniorrhaphy under general field anesthesia. Methods: Gross and ultrasound anatomy of the ventral abdomen and the diffusion of a new methylene blue solution after injection within the rectus sheath were described in seven fresh calf cadavers. Then, fourteen calves undergoing elective herniorrhaphy were randomly assigned to receive either bilateral ultrasound-guided RSB with 0.3 mL/kg of bupivacaine 0.25% and 0.15 µg/kg of dexmedetomidine or 0.3 mL/kg of 0.9% NaCl (control). Intraoperative data included cardiopulmonary variables and anesthetic requirements. Postoperative data included pain scores, sedation scores and peri-incisional mechanical threshold assessed by force algometry at specific time points after anesthetic recovery. Treatments were compared using Wilcoxon rank-sum, Student's t-test, and Cox proportional hazard model as appropriate. Mixed effect linear models on rank, with random effect calf; fixed effects time, treatment, and their interaction were used to compare pain scores and mechanical thresholds over time. Significance was set at p = 0.05. Results and Discussion: Calves receiving RSB recorded lower pain scores between 45 - 120 minutes (p < 0.05) and at 240 min after recovery (p = 0.02). And they recorded higher mechanical thresholds between 45 and 120 min after surgery (p < 0.05). Ultrasound-guided RSB provided effective perioperative analgesia in calves undergoing herniorrhaphy under field conditions.

A computed tomography-based method for the assessment of canine retrobulbar cone volume for ophthalmic anaesthesia.

OBJECTIVE: To develop a comprehensive formula for calculating the volume of local anaesthetic solution used for retrobulbar anaesthesia in dogs with different skull morphologies. STUDY DESIGN: Retrospective cohort imaging study. ANIMALS: Skull computed tomography (CT) images of 188 dogs of different breeds collected between January 2009 and December 2017. METHODS: Anatomical integrity of the orbit and adjacent structures, presenting complaint, clinical signs and CT findings were verified to exclude ocular abnormalities. The volume of the retrobulbar cone of 376 eyes was calculated using CT scans of the dogs' skulls. Additional data recorded included morphology of the skull, body weight, sex and size of the dogs, all of which were matched for possible association to the retrobulbar cone volume through univariable and multivariable linear regression models. Results of linear regression models were expressed as estimated beta coefficients with the corresponding 95% confidence intervals (95% CIs). RESULTS: Using univariate analysis, the retrobulbar cone volume was positively associated with weight and male sex. In addition, brachycephalic and dolichocephalic dogs showed a larger retrobulbar cone volume than mesocephalic dogs, while sex was no longer significantly associated with the retrobulbar cone volume. In multivariate analysis, when considering all variables in the model, weight emerged as the strongest predictor (beta coefficient: 0.062 mL kg-1, 95% CI: 0.056-0.067 mL kg-1, p < 0.001). CONCLUSIONS: and clinical relevance In the veterinary literature, there is no agreement on the precise volume of local anaesthetic solution that should be used to achieve intraconal retrobulbar anaesthesia in dogs. Here we suggest a formula to calculate the retrobulbar cone volume and, accordingly, the injection volume of local anaesthetic solution for effective retrobulbar anaesthesia.

Ultrasound-guided dorsal approach for the brachial plexus block in common kestrels (Falco tinnunculus): a cadaver study.

OBJECTIVE: To develop an ultrasound-guided dorsal approach to the brachial plexus and to investigate the nerve distribution and staining of a dyed injectate in common kestrel (Falco tinnunculus) cadavers. STUDY DESIGN: Prospective, cadaver study. ANIMALS: A group of three common kestrel cadavers (six wings). METHODS: All cadavers were fresh-frozen at -20 °C and thawed for 10 hours at room temperature before the study. The cadavers were placed in sternal recumbency and their wings were abducted. A 8-13 MHz linear-array transducer was placed over the scapulohumeral joint, at the centre of a triangle formed by the scapula and the humerus. The brachial plexus was identified between the scapulohumeralis muscle and the pectoralis major muscle, as hypoechoic structures lying just cranially to the axillary vessels. After ultrasound-guided brachial plexus identification, a 22 gauge, 50 mm insulated needle was advanced in-plane using ultrasound visualization. A volume of 0.5 mL kg-1 of a 3:1 (2% lidocaine:methylene blue) solution was injected. Following cadaver dissection, the pattern of the spread was assessed, and the extent of nerve staining was measured with a calliper and deemed adequate if more than 0.6 cm of the nerve staining was achieved. RESULTS: The brachial plexus was clearly identified in all wings with the dorsal approach. After dye injection, all the branches of the brachial plexus defined as nerves 1-5 (N1, N2, N3, N4 and N5) were completely stained in five (83%) and partially stained in one (17%) of the six wings. CONCLUSIONS AND CLINICAL RELEVANCE: The ultrasound-guided dorsal approach allows a clear visualization of the brachial plexus structure. The injection of 0.5 mL kg-1of a lidocaine/dye solution produced complete nerve staining in most cases. Further in vivo studies are mandatory to confirm the clinical efficacy of this locoregional anaesthesia technique in common kestrels (Falco tinnunculus).

An ultrasound-guided subparaneural approach to the sciatic nerve in the dog: a cadaver study.

OBJECTIVE: To describe the gross and microscopic anatomy of the sciatic nerve paraneural sheath and to report an ultrasound (US)-guided subparaneural approach to the sciatic nerve in dogs, comparing two different volumes of injectate. STUDY DESIGN: Prospective, randomized, anatomical study. ANIMALS: A group of nine middle-sized adult Mongrel canine cadavers (18 limbs). METHODS: The sciatic nerves of three pelvic limbs of two canine cadavers were identified, exposed and isolated between the greater trochanter and the popliteal fossa for gross anatomical and microscopic examination. An additional three pelvic limbs were surgically dissected on the lateral surface of the limb; the sciatic nerves were isolated, and a 26 gauge over-the-needle catheter was inserted through the paraneural sheath under direct visualization. A methylene blue solution was then slowly injected into the subparaneural compartment through the catheter under US visualization using an 8-13 MHz linear-array transducer. Subsequently, 12 pelvic limbs (six cadavers) were randomly allocated to one of two groups; using US-guided percutaneous subparaneural approach, either 0.1 or 0.05 mL kg-1of a 1:1 solution of methylene blue and 0.5% bupivacaine was injected. The spread of the dye solution and the amount of nerve staining were macroscopically scored. The stained sciatic nerves with their sheaths were then harvested for microscopic examination. RESULTS: The paraneural sciatic nerve sheath was easily identified distinct from the nerve trunk both macroscopically and with US visualization, and microscopically. Complete staining was achieved in five of six (83.3%) sciatic nerves in each group; no difference was found in the amount of staining between the two groups. Microscopically, no signs of sciatic nerve intraneural injection were observed. CONCLUSIONS AND CLINICAL RELEVANCE: The US-guided subparaneural injection of 0.05 mL kg-1 of a dye injectate resulted in satisfactory nerve staining without evidence of sciatic nerve intraneural injection.

Schirmer Tear Test Value and Corneal Lesions' Incidence during General Anesthesia for Non-Ophthalmic Surgery in Non-Brachycephalic Dogs: A Pilot Study Comparing Three Different Lubricant Eye Drop Formulations.

Aim of this blinded, prospective, randomized clinical study was to compare three different lubricant eye drops (LED) in healthy adult dogs undergoing general anaesthesia (GA) for non-ophthalmic surgery. Tear production rate was monitored by means of Schirmer tear test-1 (STT-1), and incidence of post-operative corneal abrasions/ulcerations was detected by corneal staining. A complete ophthalmic examination was performed before premedication, at extubation time and 24 h after GA in twenty-five non-brachycephalic dogs (fifty eyes) undergoing elective orthopaedic or spinal surgery procedures. Dogs were randomly allocated to one of three groups receiving as prophylactic LED either carmellose sodium (GC), or 1% hyaluronic acid (GH), or 0.25% hyaluronic acid (GL). In each eye STT-1 was repeated every hour during GA, before instilling one drop of the assigned LED. In all groups STT-1 values drastically decreased during GA, while 24 h later nine eyes (18%) had STT-1 values lower than 15 mm/minute. All of the three formulations tested were fully effective in preventing corneal ulceration (0% in all groups), while 10% of eyes reported superficial de-epithelialization. Fluorescein staining demonstrated that hourly prophylactic LED application prevented exposure keratopathy during general anesthesia in 90% of the eyes in non-brachycephalic dogs.

Comparison of the sedative effects of alfaxalone and methadone with or without midazolam in dogs.

This blinded, randomized, prospective study evaluated the sedative and physiologic effects of a combination of alfaxalone and methadone with or without midazolam in adult dogs. Sixteen dogs received methadone (0.5 mg/kg body weight) and alfaxalone (1 mg/kg body weight), either with or without midazolam (0.5 mg/kg body weight), by intramuscular injection. Quality of sedation, heart rate, respiratory rate, systolic arterial pressure, rectal temperature, arterial oxygen saturation of hemoglobin, and dose of alfaxalone required for endotracheal intubation were recorded. Sedation score increased over time in both groups; however, dogs premedicated with methadone and alfaxalone appeared significantly less sedated than dogs premedicated with midazolam at 15, 20, and 25 minutes post-injection (P = 0.04). Dogs receiving methadone and alfaxalone were almost 5 times more likely to show excitement than those receiving midazolam (P = 0.03). We concluded that adding midazolam to an intramuscular combination of methadone and alfaxalone cannot be recommended in healthy dogs.

Comparaison des effets sédatifs de l'alfaxalone et de la méthadone avec ou sans midazolam chez le chien. Cette étude prospective randomisée à l'aveugle a évalué les effets sédatifs et physiologiques d'une association d'alfaxalone et de méthadone avec ou sans midazolam chez le chien adulte. Seize chiens ont reçu par voie intramusculaire (IM) méthadone (0,5 mg/kg) et alfaxalone (1 mg/kg) (MA) ou méthadone et alfaxalone à les même dosages plus midazolam (0,5 mg/kg) (MMA). La qualité de la sédation, la fréquence cardiaque, la fréquence respiratoire, la pression artérielle systolique, la température rectale, la saturation artérielle en oxygène de l'hémoglobine et la dose d'alfaxalone requise pour l'intubation endotrachéale ont été enregistrées. Le score de sédation augmentait avec le temps dans les deux groupes, cependant, les chiens ayant reçu la combinaison MMA semblaient significativement moins sous sédation que les chiens ayant reçu la combinaison MA 15, 20, et 25 minutes après l'injection (P = 0,04). Les chiens recevant MMA étaient presque cinq fois plus susceptibles de montrer de l'excitation que ceux recevant du MA (P = 0,03). Nous avons conclu que l'ajout de midazolam à une combinaison IM de méthadone et d'alfaxalone ne peut pas être recommandé chez les chiens en santé.(Traduit par les auteurs).

Comparison of intraocular pressure and pupil diameter after sedation with either acepromazine or dexmedetomidine in healthy dogs.

OBJECTIVE: To compare intraocular pressure (IOP) and pupillary diameter (PD) following intravenous (IV) administration of dexmedetomidine and acepromazine in dogs. STUDY DESIGN: Prospective, randomized experimental trial. ANIMALS: A group of 16 healthy adult dogs aged (mean ± standard deviation) 4.9 ± 3.3 years and weighing 15.7 ± 9.6 kg, without pre-existing ophthalmic disease. METHODS: IV dexmedetomidine hydrochloride (0.002 mg kg-1; DEX) or acepromazine maleate (0.015 mg kg-1; ACE) was administered randomly to 16 dogs (eight per group). The IOP and PD, measured using applanation tonometry and Schirmer's strips mm scale, respectively, and the heart rate (HR), systolic (SAP), mean (MAP) and diastolic (DAP) arterial pressures and respiratory rate (fR) were recorded at baseline, at time of injection, and then 5, 10, 15, 20 and 25 minutes after injection. A single ophthalmologist, unaware of treatment, performed all measurements under consistent light conditions. Values were compared with baseline and among treatments using a multivariate mixed-effects model (p ≤ 0.05). RESULTS: The IOP was significantly lower in the DEX group compared with the ACE group at 10 (p < 0.01) and 15 minutes (p < 0.01) after drug injection. PD was significantly smaller compared to baseline for the entire duration of the study (p < 0.01) in both groups. Dogs in the DEX group had significant lower HR (p < 0.01) and fR (p < 0.01), higher SAP (p < 0.01) and DAP (p < 0.01) at all time points, and higher MAP (p < 0.01) during the first 15 minutes following drug injection in comparison with the ACE group. CONCLUSIONS AND CLINICAL RELEVANCE: Our results suggest that premedication with IV dexmedetomidine temporarily decreases IOP when compared with IV acepromazine. Both drugs cause miosis.

Sedative and cardiovascular effects of intranasal or intramuscular dexmedetomidine in healthy dogs.

OBJECTIVE: To compare the clinical effects and sedation scores following either intranasal (IN) or intramuscular (IM) administration of dexmedetomidine in dogs. STUDY DESIGN: Prospective, blinded, randomized, clinical study. ANIMALS: A total of 20 client-owned dogs scheduled for noninvasive diagnostic procedures. METHODS: Dogs were allocated to be administered dexmedetomidine 0.02 mg kg-1 IN (IN group) or IM (IM group). Sedation was scored before and at 5 minute intervals (for 45 minutes) after drug administration using a composite simple descriptive sedation scale giving a score of 0 (not sedated) to 13 (well sedated). Respiratory frequency (fR), heart rate, haemoglobin oxygen saturation (SpO2) and noninvasive arterial blood pressure were recorded every 5 minutes for 45 minutes. Normally distributed data were analyzed using two-way ANOVA and post hoc Sidak's multiple comparison test. Non-normally distributed data were compared using the Scheier Ray Hare test and post hoc Mann-Whitney U test. Statistical significance was set at p<0.05. RESULTS: Weight, age and sex were not different between groups. Dexmedetomidine onset of action after IN administration was not shorter compared to IM administration (6.3±3.3 versus 9.4±4.6 minutes, p=0.120). Sedation score in the IN group was higher [10 (0-11)] compared to the IM group [6 (0-8)] (p<0.001). At time of peak sedation, heart rate decreased 56% from baseline values in the IM group, and 18% in the IN group. No significant differences in SpO2 and fR were found between the two groups at any time point. No undesirable effects were observed. CONCLUSIONS AND CLINICAL RELEVANCE: Intranasal dexmedetomidine 0.02 mg kg-1 produced effective sedation with less bradycardia and more profound sedation compared to IM administration in healthy dogs and may be considered as an alternative route for dexmedetomidine administration in dogs.

A novel supra-temporal approach to retrobulbar anaesthesia in dogs: Preliminary study in cadavers.

A novel supra-temporal technique for retrobulbar anaesthesia in dogs is described and compared to the inferior temporal palpebral approach. Supra-temporal and inferior temporal palpebral retrobulbar injections were performed in 20 orbits of canine cadavers. Distribution of injected contrast medium within the intraconal space and around the optic nerve was analysed using computed tomography. There was adequate distribution of contrast medium within the intraconal space with both techniques. Concurrent intraconal and extraconal distribution was observed using the inferior temporal palpebral approach in 3/10 orbits and using the supra-temporal approach in 5/10 orbits. In 3/10 supra-temporal injections, the injected vehicle was distributed preferentially in the caudal aspect of the retrobulbar cone, closer to the orbital fissure. Accidental intraocular injection was never observed. The supra-temporal approach appears to be a valid alternative to the inferior temporal palpebral approach for retrobulbar anaesthesia in dogs, being less technically challenging. Further studies are required to confirm the clinical efficacy of this approach in dogs.

Preclinical imaging anesthesia in rodents.

Despite the outstanding progress achieved by preclinical imaging science, laboratory animal anesthesia remains quite stationary. Ninety percent of preclinical imaging studies are carried on small rodents (mice and rats) anesthetized by outdated injectable and/or inhalation agents. A need for imaging awake (conscious) animals is questionably registered mainly for brain research, for phMRI and for accomplishing pain and analgesia studies. A need for improving current rodent anesthesia protocols and for enforcing the 3Rs paradigm is sought. Patient monitoring throughout the procedure and recovery phases, as well as vital parameter's data must be recorded in basic consciousness states and during imaging sessions. A multidrug approach is suggested to overcome the limits of monoanesthesia and well-timed physiological data are required to ground findings and to interpret imaging data.

Transnasal administration of a combination of dexmedetomidine, midazolam and butorphanol produces deep sedation in New Zealand White rabbits.

OBJECTIVE: To study the sedative and cardiorespiratory effects of transnasal (TN) administration of a combination of dexmedetomidine (DEX), midazolam (MID) and butorphanol (BUT) administered through a nasal catheter to rabbits undergoing diagnostic procedures. STUDY DESIGN: Descriptive cross-sectional experimental study. ANIMALS: Eight healthy New Zealand White rabbit does (12 ± 1 months old, 3.5 ± 0.3 kg). METHODS: DEX (0.1 mg kg(-1)), MID (2 mg kg(-1)) and BUT (0.4 mg kg(-1)) were mixed (DMB) in a syringe and applied to the rabbits' nasopharyngeal mucosa after the accurate catheterization of one nostril. The onset, duration and quality of effects including analgesia were scored using a numeric rating scale of sedation for rabbits. Continuous monitoring of vital parameters was performed via clinical and multiparametric recording. Physiological variables were explored using repeated measures anova for parametric data or Friedman's test for non-parametric data. Tukey's or Dunn's post hoc multiple comparisons test was used depending on normality. The statistical significance was set at p < 0.05. RESULTS: Loss of the righting reflex, deep sedation and profound analgesia ensued simultaneously at 1.4 ± 1.1 minutes after DMB administration. These effects lasted 45 minutes before subsiding into moderate sedation, which lasted for an additional 25 minutes. Residual central nervous system impairment persisted up to 100 minutes. Blood pressure dropped progressively over time by 50%, whereas respiratory frequency decreased by 70%, consistent with moderate hypoxemia and hypercarbia. CONCLUSION AND CLINICAL RELEVANCE: The TN route is a reliable and effective means for administration of DEX, MID and BUT to rabbits. The overall profound sedative effects and analgesic proprieties of the DMB combination can be selectively reversed depending on the needs of the procedure. Oxygen supplementation and careful monitoring are mandatory even in healthy subjects. The DMB protocol should be cautiously used in rabbits with cardiovascular or respiratory deficiencies.

Acupuncture and pharmacopuncture are as effective as morphine or carprofen for postoperative analgesia in bitches undergoing ovariohysterectomy

ABSTRACT PURPOSE : To investigate the analgesic effect of acupuncture (AP) or micro-dose pharmacopuncture (PA), using carprofen or morphine, in bitches undergoing ovariohysterectomy (OHE). METHODS: Thirty five dogs were randomly assigned to five groups after sedation with acepromazine IM: AP, 0.5 mg.kg-1 of morphine subcutaneously (SC), 4 mg.kg-1 of carprofen SC, and PA with 0.05 mg.kg-1 of morphine or 0.4 mg.kg-1 of carprofen. Anaesthesia was induced with propofol and maintained with isoflurane. Pain was assessed after OHE by a blind observer for 24h, by dynamic visual analogue scale (DIVAS), Glasgow (CMPS-SF), Melbourne (UMPS) and Colorado University pain scale (CSU). Animals reaching 33% of the UMPS score received rescue analgesia with morphine IM. Non parametric data were analysed by Kruskal-Wallis or Friedman tests where applicable, followed by Dunn´s test. Parametric data were analysed by two way ANOVA, followed by Tukey test. RESULTS: There were no differences among groups in number of rescue analgesia. Except for the DIVAS score where animals treated with morphine had the lowest score compared with AP and carprofen, at 1h after surgery, there were no other differences among groups. CONCLUSION: Acupuncture or pharmacopuncture were equally effective as morphine or carprofen to control postoperative pain in bitches undergoing ovariohysterectomy.

Acupuncture and pharmacopuncture are as effective as morphine or carprofen for postoperative analgesia in bitches undergoing ovariohysterectomy.

PURPOSE: To investigate the analgesic effect of acupuncture (AP) or micro-dose pharmacopuncture (PA), using carprofen or morphine, in bitches undergoing ovariohysterectomy (OHE). METHODS: Thirty five dogs were randomly assigned to five groups after sedation with acepromazine IM: AP, 0.5 mg.kg(-1) of morphine subcutaneously (SC), 4 mg.kg(-1) of carprofen SC, and PA with 0.05 mg.kg(-1) of morphine or 0.4 mg.kg(-1) of carprofen. Anaesthesia was induced with propofol and maintained with isoflurane. Pain was assessed after OHE by a blind observer for 24h, by dynamic visual analogue scale (DIVAS), Glasgow (CMPS-SF), Melbourne (UMPS) and Colorado University pain scale (CSU). Animals reaching 33% of the UMPS score received rescue analgesia with morphine IM. Non parametric data were analysed by Kruskal-Wallis or Friedman tests where applicable, followed by Dunn's test. Parametric data were analysed by two way ANOVA, followed by Tukey test. RESULTS: There were no differences among groups in number of rescue analgesia. Except for the DIVAS score where animals treated with morphine had the lowest score compared with AP and carprofen, at 1h after surgery, there were no other differences among groups. CONCLUSION: Acupuncture or pharmacopuncture were equally effective as morphine or carprofen to control postoperative pain in bitches undergoing ovariohysterectomy.

Effects of some anesthetic agents on skin microcirculation evaluated by laser Doppler perfusion imaging in mice.

BACKGROUND: Anesthetic agents alter microcirculation, influencing tissue oxygenation and delivery of vital substrates. Laser Doppler perfusion imaging is a widespread technique in the field of microvascular research that can evaluate noninvasively and in real time the effects of environmental conditions, physical manipulations, diseases and treatments on peripheral perfusion. This study aims to evaluate laser Doppler perfusion imaging as a means to detect changes in skin microcirculation induced by some popular anesthetic agents in a murine model. Twenty-four age- and gender-matched healthy CD1 mice were examined by laser Doppler perfusion imaging. The skin microcirculatory response was measured at the level of plantar surfaces during isoflurane anesthesia with or without subsequent dexmedetomidine or acepromazine. At the end of the procedure, dexmedetomidine was reversed by atipamezole administration. RESULTS: In all mice, skin blood flow under isoflurane anesthesia did not show significant differences over time (P = 0.1). The serial perfusion pattern and values following acepromazine or dexmedetomidine administration differed significantly (P < 0.05). CONCLUSIONS: We standardized a reliable laser Doppler perfusion imaging protocol to non-invasively assess changes in skin microcirculation induced by anesthesia in mice, considering the advantages and drawbacks of this technique and its translational value.

Mice anesthesia, analgesia, and care, Part I: anesthetic considerations in preclinical research.

Animal experiments are necessary for a better understanding of diseases and for developing new therapeutic strategies. The mouse (Mus musculus) is currently the most popular laboratory animal in biomedical research. Experimental procedures on animals often require anesthesia and/or analgesia to obtain adequate immobilization and to reduce stress or pain. Mice anesthesia is challenging for several reasons including the animals' size, metabolic rate, and the high risk of hypothermia and hypoglycemia. Moreover, anesthetic agents influence physiological parameters, further interfering with experimental results. Small animal imaging procedures are increasingly used in biomedical research both because the animals allow in vivo monitoring and because they are readily available for longitudinal and noninvasive studies as well as investigations into the evolution of diseases and the effects of new therapies. Anesthesia must adapt to the imaging technique, the procedure length, and the aim of the study. The purpose of this article is to review the existing literature on anesthetic protocols adopted in mice for molecular imaging studies and to report our experience.

Mice anesthesia, analgesia, and care, Part II: anesthetic considerations in preclinical imaging studies.

Animal experiments are necessary for a better understanding of diseases and for developing new therapeutic strategies. The mouse (Mus musculus) is currently the most popular laboratory animal in biomedical research. Mice imaging procedures are increasingly used in preclinical research because they allow in vivo monitoring and they are readily available for longitudinal and noninvasive studies as well as investigations into the evolution of diseases and the effects of new therapies. New imaging techniques and sophisticated laboratory animal imaging tools are currently producing a large body of evidence about the possible interference of anesthesia with different imaging methods that have the potential to compromise the results of in vivo studies. The purpose of this article is to review the existing literature on molecular imaging studies in mice, to describe the effects of different anesthetic protocols on their outcome, and to report our own experience with such studies.