Comparison of Butorphanol, Methadone, and Pethidine in Combination with Alfaxalone for Premedication in Isoflurane-Anesthetized Cats Undergoing Ovariectomy.

The aim of this study was to compare three different anesthetic protocols administered intramuscularly (IM) in cats undergoing elective ovariectomy, while evaluating the quality of sedation, antinociceptive, isoflurane-sparing effect, and analgesia in the intra-operative and post-operative phases. A total of 71 female cats were sedated IM with alfaxalone (3 mg/kg) combined with either butorphanol (0.3 mg/kg), methadone (0.3 mg/kg), or pethidine (5 mg/kg). During surgery, vital parameters were constantly monitored; at the end of the procedure, the quality of recovery was assessed through a specific form and each cat was scored for perceived pain using the UNESP-Botucatu scale for 5 days, and rescue analgesia was provided with buprenorphine IM when indicated. Moreover, differences between two different post-operative resting regimens (hospital kennels vs. home) were also assessed. A significant difference emerged for the amount of IM dexmedetomidine required to achieve an adequate level of sedation for intravenous catheterization, highlighting a greater need in the pethidine group (p = 0.021). There was no significant difference between opioid groups for the requirement of intra-operative rescue analgesia, and the clinical parameters were kept within physiological ranges regardless of the opioid used in premedication. Lastly, differences between the UNESP-Botucatu scores were detected from day 3 to day 5 post-operatively, with lower scores in cats with home resting regimens compared to the hospitalized animals, likely due to the presence of an unfamiliar condition and the absence of a cat-friendly environment.

Cytotoxicity of local anaesthetics and protective effects of platelet rich plasma on equine tenocytes: An in vitro study.

Local anaesthetics (LAs) can have detrimental effects on rat, bovine, canine, and human tendon tissues and cells. Currently, there has been no available data on the impact of these drugs on equine tenocytes. Even if LA injection for managing painful tendon conditions in horses is limited, it is usually used via intra-articular, intrasynovial, perineural, and intrathecal as well as for lameness examinations. In this in vitro study, the cytotoxic effects of LAs, including lidocaine, mepivacaine, and bupivacaine on equine tenocytes, in the presence and absence of platelet rich plasma (PRP), were investigated. PRP accelerates tissue healing and can exert cytoprotective effects on different cell types exposed to different stressful conditions, including drugs. Results indicated that the exposure to LAs significantly reduced tenocytes viability in dose- and time-dependent manners while PRP was able to counteract their cytotoxic effects. Furthermore, microscopy and flow cytometry analyses revealed apoptosis and necrosis in equine tenocytes exposed to these drugs, that were both reduced when PRP was in the medium. These findings highlight the importance of considering the tenocyte toxicity associated with intrathecal and intraneural LA injections, as they might affect tenocytes or reduce the efficacy of associated therapies. Moreover, this study also highlights the protective effects of PRP, which could make LA injections safer.

Small Colon Faecalith with Large Colon Displacement in Ten Cases (2015-2023): A Detailed Case Description and Literature Review.

Small colon impaction can result in accumulation of ingesta, gas, and fluid orally to the impaction site in horses. Large colon tympany, which is caused by ingesta fermentation, can be a predisposing factor for intestinal displacement. The aim of this study is to report the history, clinical, and surgical findings of horses and ponies referred for abdominal pain not responsive to drugs where a right dorsal displacement (RDD) or large colon volvulus (LCV), together with a small colon faecalith (SCF), were diagnosed during surgery. This study included a total of five horses and five ponies. Based on clinical features, ultrasonographic examination, and rectal palpation, an initial suspected diagnosis of RDD, LCV or severe large colon and caecum distension was made in all clinical cases. Due to the lack of response to medical treatment or worsening of colic symptoms, surgery was performed in all horses: diagnosis of RDD or LCV was made and a SCF was incidentally detected in all cases. While exploratory laparotomy was carried out in all the patients for the presence of a large colon issue, it was probably subsequent to an obstruction of the small colon caused by the presence of an SCF, which is generally difficult to diagnose. This study reported the presence of SCF as a possible cause of secondary RDD or LCV in horses and ponies that, to the authors' knowledge, has never been reported.

Intravenous loss of over-the-wire catheter guidewires in 13 horses.

BACKGROUND: Over-the-wire (OTW) catheter placement is performed frequently in horses. Intravascular loss of a guidewire has been anecdotally reported, but there is limited information regarding the treatment and outcome of horses that have experienced this complication of OTW catheter placement. OBJECTIVES: Describe the clinical and diagnostic features, treatment, and outcome of horses experiencing IV guidewire loss at the time of OTW catheter placement. ANIMALS: Thirteen horses. METHODS: Multicenter retrospective study to identify horses with IV guidewire loss. Horses of all ages were considered for inclusion. Horses were excluded from the study if complete medical records of signalment, indication, and outcome were not available. Intravenous guidewire loss was defined as the guidewire being lost IV at the time of OTW catheter placement. RESULTS: No horses in this study experienced adverse clinical signs associated with the loss of a guidewire. Eight horses had the guidewire removed and the guidewire was left in situ in 5 horses. None of the horses with the guidewire in situ had experienced long-term effects. CONCLUSIONS AND CLINICAL IMPORTANCE: Intravenous guidewire loss seems to have a good long-term prognosis even in horses in which removal of the guidewire was not possible. Thus, in horses where guidewire removal is not feasible, guidewires that remain in situ may have limited to no adverse effects.

Retrograde Approach to Maxillary Nerve Block: An Alternative in Orofacial Surgeries in Horses.

The aim of this study was to retrospectively report outcomes resulting from the approach to the maxillary nerve block (MNB) through the infraorbital canal, in terms of needles selection, drawbacks or side effects during or after block execution, and analgesic efficacy leading to clinical and cardiovascular stability during surgery. Anesthetic records of 15 horses undergoing orofacial surgery in standing analgo-sedation (STA, n = 6) and in general anesthesia (GEN, n = 9) were retrieved and analyzed. Horses in group STA required surgery for dental extraction, nasal polyp resection and maxillary/frontal sinusitis. Horses in group GEN underwent surgery for fronto-maxillary, nasal and dental diseases. Size 19 and 20 G Tuohy needles were used in adult horses weighing 350-600 kg, while size 21 and 22 G were used in younger horses or ponies. None of the horses in both groups showed complications related to the block and physiological parameters were stable and within normal ranges during surgery; overall, an adequate anesthetic/sedation depth was achieved. Our results confirm the in vivo applicability of the MNB approached within the infraorbital canal, which had been described only on cadaveric specimens. The retrograde technique resulted in a valid and easy approach to the maxillary nerve that avoids damage to periorbital structures and side effects reported with traditional techniques.

Sedation quality of alfaxalone associated with butorphanol, methadone or pethidine in cats injected into the supraspinatus or the quadriceps muscle.

OBJECTIVES: The aim of this study was to compare the quality of sedation with three different anaesthetic protocols (alfaxalone combined with butorphanol, methadone or pethidine) administered intramuscularly in cats, and to evaluate the influence of the injection site (between supraspinatus and quadriceps muscles) on the onset and quality of sedation. METHODS: A total of 151 cats were selected for this study. Cats were sedated with alfaxalone (3 mg/kg) combined with either butorphanol (0.3 mg/kg; n = 50), methadone (0.3 mg/kg; n = 53) or pethidine (5 mg/kg; n = 48). The combination was injected intramuscularly into the supraspinatus (n = 79) or quadriceps muscle (n = 72). The data included a scoring system for the quality of sedation and physiological parameters, such as heart rate (HR), respiratory rate, body temperature and occurrence of mydriasis, monitored during the first 30 mins of anaesthesia. RESULTS: The opioid associated with alfaxalone influenced the overall sedation score, the degree of myorelaxation, the occurrence of mydriasis and HR. The overall sedation score was poorer with butorphanol than with methadone (P = 0.008), and butorphanol induced a lower degree of myorelaxation than methadone (P = 0.013). The injection into the supraspinatus showed better qualitative results for sedation and a faster onset time (in about 3 mins) than that into the quadriceps (P <0.001). HR decreased from baseline (P <0.001) and over time (P <0.001), mainly in cats of the butorphanol-supraspinatus and pethidine-quadriceps groups (P = 0.004). The occurrence of mydriasis was lower after butorphanol than after methadone and pethidine (P = 0.025), while the incidence of side effects did not differ among groups. CONCLUSIONS AND RELEVANCE: All three protocols provided a good quality of sedation and allowed performing the scheduled procedure. Moreover, the injection into the supraspinatus muscle showed superior results in all the qualitative scores of sedation and quicker onset time than that into the quadriceps muscle.

Ureteral Endoscopy to Detect Upper Urinary Tract Diseases in Horses.

Ureteral endoscopy is a routine procedure in human medicine, whereas the reports of this procedure on horses are few and far between. The aim of this paper is to describe the endoscopic technique to evaluate the ureters in standing, sedated horses. An endoscopy of the ureters and lower urinary tract was performed using flexible endoscopes on 4 horses, 3 mares and one gelding. The animals were sedated with alpha-2-agonists and an epidural anaesthesia was given. An endoscopy of the ureter in the horse is easy to perform, causes the animal no adverse effects and could provide significant information on the diagnosis and prognosis of diseases of the urinary tract.

Methadone or Butorphanol as Pre-Anaesthetic Agents Combined with Romifidine in Horses Undergoing Elective Surgery: Qualitative Assessment of Sedation and Induction.

While butorphanol is the most commonly used opioid in horses, methadone is not licensed in most countries. Our aim was to compare the effects of both drugs, combined with romifidine, regarding the quality of sedation and induction in horses undergoing elective surgery. Results indicate the suitability of both methadone and butorphanol in this patient population. Animals were scored 10 min after intravenous injection of sedatives. Despite lower overall sedation (OS) score in horses receiving methadone (p = 0.002), the quality and time of induction and intubation remained unchanged. None of the horses had the lowest OS score (no sedation), nor the highest score for ataxia (horse falling). Methadone induced a tendency for minor noise reaction yet minor head lowering scores, the latter being probably the most influencing parameter when scoring OS. Measured physiological parameters decreased in both groups, with greater bradycardia recorded after methadone (p = 0.017), including a higher incidence of atrioventricular blocks that resolved during general anaesthesia. The quality of induction was good-excellent in most of the animals. While comparisons between the degree of antinociception were beyond the scope of this study, analgesic potency might influence the choice when considering opioids as pre-anaesthetic drugs in combination with romifidine before surgery in equines.

Diagnostic and Clinical Course of Small Colon Recurrent Impaction Associated with Severe Myenteric Ganglionopathy in A Mare.

A 10-year-old Koninklijk Warmbloed Paardenstamboek Nederland (KWPN, Netherlands-based organization for registration of the Dutch Warmblood horses) mare was evaluated three times over four months because of recurrent colic. At every referral, a physical examination revealed a small colon impaction, which partially responded to food deprivation and oral administration of water and magnesium sulphate. Due to the recurrent nature of the small colon impaction, several differential diagnoses were considered: inflammatory bowel disease (IBD), chronic salmonellosis and myenteric ganglionopathies. At first admission, an exploratory laparotomy was proposed, but the owner declined. On the second hospitalisation, the mare underwent a standing exploratory laparoscopy, but no abnormality related to the small colon was detected and resolved with a soap-based enema. At the third hospitalisation, the owner agreed to the exploratory laparotomy, which allowed surgical biopsies of the caecum and the large and small colon. Lymphomonocytic enteritis and mild myenteric ganglionitis were diagnosed. After laparotomy, the mare regularly fed and defecated, but a few days later, tachycardia, fever and abundant gastric reflux occurred. As the clinical condition rapidly deteriorated, the owner elected for euthanasia. A post-mortem histological examination showed severe chronic lymphocytic enterocolitis and typhlitis associated with the marked depletion of myenteric ganglion bodies. Small colon impaction is a very common disorder of the small colon in horses. In the presence of myenteric ganglionopathies, this case proposes the controversial matter of primary or secondary disorders of enteric neuromuscular function as the base of repeated small colon impactions of the horse. In this mare, recurrent small colon impaction was considered secondary to severe myenteric ganglionopathy associated with chronic intestinal pseudo-obstruction.

Comparison of Mesh and Barbed Suture for Laparoscopic Nephrosplenic Space Ablation in Horses.

Nephrosplenic space (NSS) ablation has been demonstrated to be an effective technique for prevention of left dorsal displacement of the large colon and multiple laparoscopic techniques, among which ablation with mesh or with a barbed suture, have been proposed. Our objective was to compare two laparoscopic techniques for closure of the NSS in twenty-eight horses diagnosed with nephrosplenic entrapment. Medical records of horses that had laparoscopic NSS ablation in two referral centers between 2017-2019 were retrieved. Duration of surgery, complications, and short- and long-term follow-up information were collected and compared. Costs were also calculated and compared. All horses met the inclusion criteria: 9 had NSS ablation with a mesh implant (group M), 19 with barbed suture material (group B). One horse in group B had recurrent colic after discharge. At control laparoscopy after 5 months, the NSS resulted in still not being ablated because of a failure of the suture. In group M, three horses had recurrent colic. One was successfully treated medically, one died of unknown causes and the third required a second laparoscopic suturing at 3-6 months because of failure of the mesh implant. The mean time of surgery and costs were lower in group B compared to group M. The barbed suture technique was faster, more cost-effective and had a lower complication rate than the mesh implant.

Successful Surgical and Medical Management of a Pararectal Abscess in a Horse.

Pararectal abscesses are life-threatening conditions that can rupture and cause septic peritonitis. The objective of this case report is to describe aggressive treatment of a pararectal abscess to allow a quick return to competitions. A 14-year-old pony was admitted to the Veterinary Teaching Hospital (VTH) of the University of Perugia because of a suspected intra-abdominal mass. Two weeks earlier, it exhibited clinical signs compatible with colic which was treated medically; however, because of the persistence of a firm mass on the right side of the abdomen noted on rectal palpation, the pony was admitted to the VTH. Based on rectal palpation, rectal ultrasound, neutrophilic leukocytosis, hyperfibrinogenemia, and elevated alkaline phosphatase, the diagnosis of a pararectal abscess was made. The horse was treated with ceftiofur IM and MgSO4/paraffin oil via a nasogastric tube. Standing surgical drainage of the abscess with placement of an indwelling drain was performed, followed by daily lavages with rifampicin and acetylcysteine along with Ringer lactate solution with subsequent passive drainage. A bacterial culture revealed the presence of Streptococcus zooepidemicus that was treated with oral rifampicin. Standing laparoscopy revealed adhesions to the rectum. An epidural catheter was placed for repeated delivery of morphine sulfate. The pony was monitored daily by rectal examination, while complete blood count, fibrinogen, serum amyloid A, and abdominal ultrasound (to assess the size of the abscess) were repeated weekly. The pony progressively improved and was discharged one month later, shortly returning to competitions. This report emphasizes the importance of combining medical and surgical treatments for pararectal abscesses.

Intra-articular use of analgesic/antinflammatory drugs in dogs and horses.

Joint pain is a major cause of lameness in animals such as horses and dogs, and it may affect their athletic performance and quality of life. The intra-articular administration of analgesic/antinflammatory drugs is a common practice in veterinary medicine, for both lameness diagnosis and joint pain management. It is used either perioperatively, such as in animals undergoing arthroscopy/arthrotomy, and in osteoarthritic animals. However, evidence regarding efficacy and safety of each drug is limited, and controversies persist in these areas. In particular, it is often uncertain whether a defined treatment is effective by simply relieving the symptomatic pain associated with the joint disease, or whether it has a positive effect on the joint environment. Moreover, there is still much hesitation about treatments for joint diseases, related to the time of their application for the best outcome, and to any possible deleterious side effects. This article includes a review of the literature concerning the main analgesic/antinflammatory drugs used intra-articularly for managing acute and chronic joint pain/inflammation in dogs and horses. Three main issues for each class of drugs are considered, including clinical efficacy, pharmacokinetics, and local cytotoxic effects.

Gonadectomy in Raccoons: Anesthetic and Cardiorespiratory Effects of Two Ketamine-Based Pre-Anesthetic Protocols before Sevoflurane-Sufentanil.

Nineteen raccoons were enrolled in this study. The aim was to evaluate and compare the quality of anesthesia and the cardiorespiratory effects following treatment with a ketamine-based combination with either dexmedetomidine (KD group) or midazolam (KM group) in raccoons undergoing ovariohysterectomy/orchiectomy. General anesthesia was maintained with sevoflurane in oxygen and sufentanil infusion. The time required to approach the animals was similar among groups resulting in a median of 5 min after IM injection. Animals in group KD were scored with greater myorelaxation (p < 0.01) and easier intubation (p < 0.05). Moreover 70% of them did not require other drugs for tracheal intubation unlike animals in group KM, which required propofol in 100% of cases. After intubation and connection to the breathing circuit, physiological parameters were monitored continuously and recorded every 5 min. Sevoflurane requirements were lower in group KD than KM (p = 0.005). Blood pressure was maintained within physiological ranges in both groups but with higher values in group KM (p < 0.05). Mild respiratory depression occurred during surgery and animals in group KM showed greater respiratory acidosis (p < 0.05). Recovery was smooth and uneventful in all animals. Both anesthetic protocols can be recommended for safe anesthesia in wild raccoons.

A Comparative Study of Intramuscular Alfaxalone- or Ketamine-Based Anesthetic Mixtures in Gray Squirrels Undergoing Gonadectomy: Clinical and Physiologic Findings.

The gray squirrel is one of the most common invasive species in Europe, whose presence is dangerous for the survival of the European red squirrel. To cope with this biological invasion and to safeguard biodiversity, the LIFE+U-SAVEREDS project aims to protect the red squirrel, by limiting the growth of the current population of gray squirrels and simultaneously promoting their eradication with surgical sterilization. This study compares two different anesthetic protocols, including dexmedetomidine (40 µg/kg) and midazolam (0.3 mg/kg) associated with ketamine (15 mg/kg; n = 25 squirrels) or alfaxalone (5 mg/kg; n = 22 squirrels). A blinded investigator evaluated the quality and onset of sedation, intraoperative anesthesia, and recovery, as well as the physiologic parameters for each animal. Alfaxalone provided a good quality of anesthesia with limited cardiovascular effects (p < 0.05) and good intraoperative myorelaxation. Ketamine induced complete relaxation in a shorter time (p < 0.05) and a rapid (p < 0.001) and excellent (p < 0.05) recovery. Despite the overall superiority of ketamine, alfaxalone appeared to be an adequate alternative anesthetic drug that can be administered without requiring intravascular access. It should be rapidly metabolized and excreted; however, it requires the combination of longer acting sedatives/myorelaxants to prevent a poor recovery quality.

Pharmacokinetics and analgesic efficacy of intranasal administration of tramadol in dogs after ovariohysterectomy.

OBJECTIVE: To assess analgesic efficacy and the pharmacokinetics of intranasal (IN) tramadol in dogs following ovariohysterectomy. STUDY DESIGN: Randomized, blinded clinical study. ANIMALS: A total of 30 bitches undergoing elective ovariohysterectomy. METHODS: Dogs were randomly assigned to one of three experimental groups (10 dogs per group): IN tramadol 4 mg kg-1 (group T-IN), intravenous (IV) tramadol 4 mg kg-1 (group T-IV) and IV methadone 0.2 mg kg-1 (group M). Drugs were administered at extubation. At established time points (before surgery and up to 8 hours after drug administration) analgesia was assessed using the Italian version of the Glasgow Composite Measure Pain Scale Short Form and physiological variables were recorded. To determine the pharmacokinetics of IN tramadol, blood samples were collected at predetermined time points. Shapiro-Wilk test was used to assess whether data were normally distributed and consequently parametric or non parametric tests were applied. A p value < 0.05 was considered significant. RESULTS: No significant intergroup differences were observed in the dogs that were administered rescue analgesia and time of its administration. Excluding dogs that were administered rescue analgesia, no significant intergroup differences emerged in pain scores and physiological variables, except for a lower rectal temperature in group M compared with the tramadol groups. After IN administration, tramadol was rapidly absorbed into the systemic circulation, reaching its maximum concentration (range 74.74-200.29 ng mL-1) within 30-60 minutes, it then decreased rapidly and was detectable in plasma for up to 2 hours after treatment in all dogs. CONCLUSIONS AND CLINICAL RELEVANCE: IN tramadol administration appears to be as effective as IV tramadol and methadone treatments in pain management of dogs after elective ovariohysterectomy. Given its low concentrations and short detection time in plasma after the IN route, systemic tramadol action appears unlikely.

Influence of neck position on commonly performed radiographic measurements of the cervical vertebral region in horses.

OBJECTIVE To determine the influence of various neck positions on cervical vertebral radiographic measurements in horses. ANIMALS 18 client-owned horses examined for lameness but free of cervical disease. PROCEDURES Laterolateral radiographs of the cervical vertebrae from C1 through T1 were acquired for each horse in 3 neck positions (low, neutral, and high). Minimum sagittal diameter, intravertebral sagittal diameter (intra-VSD) ratio, inter-VSD ratio, length of the articular processes joint ratio, vertebral alignment angle, and vertebral fossa angle were measured at each segment in each neck position. Values for the high and low positions were compared with those for the neutral position. RESULTS No significant differences from neutral position values were identified for minimum sagittal diameter, intra-VSD ratio, and vertebral fossa angle as measured in low and high neck positions. Compared with results in the neutral position, the high position resulted in a greater vertebral alignment angle at C3-4 and inter-VSD ratio at C4-5 and a lower length of the articular processes joint ratio at C2-3, C3-4, and C4-5; the low position resulted in a lower vertebral alignment angle at C4-5. However, all observed differences were small. CONCLUSIONS AND CLINICAL RELEVANCE Neck position influenced some radiographic measurements of the cervical vertebrae in horses free of cervical disease. However, because several of these measurements were not or were only minimally affected by neck position, some latitude in neck position may be possible without concern about substantially affecting radiographic measurements in this region.

A survey of ocular ultrasound abnormalities in horse: 145 cases.

PURPOSE: To describe the association of clinical and ultrasonographic (US) findings in horses affected by visual impairments, to estimate the most frequent ultrasonographic alteration as well importance and limits of US as a part of ophthalmic evaluation in equine patients. METHODS: One-hundred-forty-five horses referred to the Veterinary Teaching Hospitals of the University of Perugia and Camerino for ocular problems were submitted to ophthalmic examination and ocular ultrasound. The following group of abnormalities was established: corneal alteration, cataract, synechiae, iris prolapse, anterior chamber alterations, vitreous opacities, globe reduction, globe enlargement, retinal detachment, lens subluxation/luxation, lens rupture, intraocular masses, retrobulbar masses. Specificity, sensitivity, positive and negative predictive value and related 95% confidence interval were calculated. Kappa value was estimated for concordance evaluation. RESULTS: A total of 384 clinical alterations were observed during ophthalmological examination, while 357 were found by ultrasound investigation. A very good agreement was found for lens subluxation/luxation, intraocular masses, iris prolapse, globe enlargement, lens rupture, vitreous opacities and cataract. Moderate agreement was found for retinal detachment, anterior chamber alterations and synechiae. Corneal alteration and globe reduction resulted in a fair and poor agreement, respectively. CONCLUSIONS: Ultrasonography affords the benefit of providing a complete cross-sectional view of the eyeball, facilitating the identification of ocular diseases in cases of loss of transparency of ocular media. It also represents an indispensable aid whenever anterior opacification precludes the use of ophthalmoscopic or biomicroscopic examination techniques.

Efficacy, chondrotoxicity and plasma concentrations of tramadol following intra-articular administration in horses undergoing arthroscopy: preliminary findings.

Intra-articular administration of analgesics is performed to ensure good perioperative pain management avoiding undesirable systemic effects. To evaluate the effect of intra-articular injection of tramadol on postoperative pain after arthroscopy in horses and to determine whether tramadol had a local effect. Before the in vivo study, an in vitro test was performed aiming to evaluate the viability of equine chondrocytes after exposure to various concentrations of tramadol. The concentration identified as most appropriate was used to treat the horses' joints. Twelve horses affected by osteochondrosis were randomly assigned to two groups that were treated intra-articularly at the end of surgery with tramadol (4 mg/mL) and saline, respectively. At predetermined time-points a Composite Pain Scale was applied and blood samples were collected in order to define the extent of tramadol absorption into the systemic circulation. The Mann-Whitney test was used for statistical analysis. Serum of four out of six treated horses revealed traces of tramadol (range 10.6-19.3 ng/mL) sporadically between 0.5 and 4 hours post-treatment, while in the other two horses, no trace of drug was found. Findings suggested that any eventual effect was probably due to local action rather than systemic absorption. The pain scores obtained in tramadol-treated horses were lower between 1 and 6 hours post-administration, than those obtained in the control group, but the differences were not statistically significant. These preliminary results suggest that tramadol, at this concentration, is only mildly beneficial in the pain management of horses after arthroscopy.

Heart rate and blood pressure variations after transvascular patent ductus arteriosus occlusion in dogs.

The objective of the study was to retrospectively analyse the cardiovascular effects that occurs following the transvascular occlusion of patent ductus arteriosus in dogs. Sixteen anaesthesia records were included. Variables were recorded at the time of placing the arterial introducer, occlusion of the ductus, and from 5 to 60min thereafter, including, among the other, heart rate, systolic, diastolic and mean arterial blood pressure. The maximal percentage variation of the aforementioned physiological parameters within 60min of occlusion, compared with the values recorded at the introducer placing, was calculated. The time at which maximal variation occurred was also computed. Correlations between maximal percentage variation of physiological parameters and the diameter of the ductus and systolic and diastolic flow velocity through it were evaluated with linear regression analysis. Heart rate decreased after occlusion of the ductus with a mean maximal percentage variation of 41.0±14.8% after 21.2±13.7min. Mean and diastolic arterial blood pressure increased after occlusion with a mean maximal percentage variation of 30.6±18.1 and 55.4±27.1% after 19.6±12.1 and 15.7±10.8min, respectively. Mean arterial blood pressure variation had a significant and moderate inverse correlation with diastolic and systolic flow velocity through the ductus. Transvascular patent ductus arteriosus occlusion in anaesthetised dogs causes a significant reduction in heart rate and an increase in diastolic and mean blood arterial pressure within 20min of closure of the ductus.

Effects of xylazine and dexmedetomidine on equine articular chondrocytes in vitro.

OBJECTIVE: To assess the effects of xylazine and dexmedetomidine on equine chondrocytes, in vitro. STUDY DESIGN: Prospective, experimental study. STUDY MATERIAL: Equine articular chondrocytes from five male horses. METHODS: Chondrocytes were isolated from healthy equine articular cartilage of the metacarpo/metatarsophalangeal joints. Cell viability was assessed using the WST-8 assay by exposing chondrocytes to xylazine (0.5, 1, 2, 4, 8, 16.6, 25, 50 mg mL-1) or dexmedetomidine (0.001, 0.005, 0.01, 0.05, 0.175, 0.25 mg mL-1) for 15, 30 and 60 minutes. Based on the results of these tests, cells were treated with xylazine (1, 4, 25 mg mL-1) or dexmedetomidine (0.05, 0.175, 0.25 mg mL-1) for 15 minutes to further evaluate: cell viability by neutral red uptake; cell membrane integrity by lactate dehydrogenase release and by fluorescence microscopy with Hoechst 33342 and propidium iodide (PI), and apoptosis by flow cytometry using double staining with annexin V-fluorescein isothiocyanate/PI and by cell morphology. RESULTS: Both drugs reduced cell viability in a dose-dependent manner. Specifically, all xylazine concentrations, except 0.5 mg mL-1 and 1 mg mL-1, significantly reduced cell viability, whereas the effects of dexmedetomidine were evident only at 0.175 mg mL-1 and 0.25 mg mL-1. The highest concentrations of xylazine (25 mg mL-1) and dexmedetomidine (0.25 mg mL-1) caused loss of membrane integrity. Cell morphology and flow cytometry analyses demonstrated signs of late apoptosis in xylazine-treated cells, and signs of late apoptosis and necrosis in dexmedetomidine-treated cells. CONCLUSIONS AND CLINICAL RELEVANCE: This study offers new insights into the potential chondrotoxicity induced by dexmedetomidine and xylazine. Therefore, the intra-articular administration of α2-agonists should be conducted with care, especially for doses of ≥ 4 mg mL-1 of xylazine and 0.175 mg mL-1 and 0.25 mg mL-1 of dexmedetomidine.