Alexander Valverde

Alexander Valverde
University of Guelph | UOGuelph · Department of Clinical Studies

DVM, DVSc, Diplomate ACVA

About

108
Publications
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2,237
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Additional affiliations
September 2005 - present
University of Guelph
February 2001 - July 2005
University of Florida

Publications

Publications (108)
Article
The objective of this study was to design and assess the validity and reliability of a new feline multiparametric sedation scale (FMSS). A total of 89 household cats were recruited, enabling a total of 534 sedation assessments. Every assessment was performed by 3 blinded observers with varying expertise levels (Level 1: Student; Level 2: RVT; Level...
Chapter
This chapter focuses on unique features in the horse that may be of benefit for clinical understanding. The general considerations regarding anesthetic drug selection, delivery, and monitoring techniques in animals undergoing urogenital surgery using sedation or anesthesia are similar to those of the non-pregnant animal. Pregnancy causes major adap...
Article
Objectives The aim of this study was to evaluate the change in packed cell volume (PCV) and total protein following intramuscular preanesthetic sedation with one of three drug combinations in cats. Methods Thirty client-owned cats were enrolled in this prospective, randomized, blinded, clinical study. A venous blood sample was obtained prior to ad...
Article
Full-text available
Resuscitative fluid therapy aims to increase stroke volume (SV) and cardiac output (CO) and restore/improve tissue oxygen delivery in patients with circulatory failure. In individualized goal-directed fluid therapy (GDFT), fluids are titrated based on the assessment of responsiveness status (i.e., the ability of an individual to increase SV and CO...
Article
Full-text available
The objective of this study was to investigate the effect of anesthesia duration on the quality of recovery in horses. The medical records of horses that were anesthetized and underwent surgery for elective and emergency soft tissue and orthopedic conditions from 2013 to 2019 were reviewed. Horses included in the study (N = 305) fulfilled the follo...
Chapter
This chapter summarizes the pre‐ and intraoperative factors that predispose to higher risk, their pathogenesis, prevention, and/or treatment. These factors include idiosyncratic characteristics of the horse, cardiorespiratory function, muscle blood flow, and logistic aspects such as proper positioning on the surgery table, anesthetic time, type of...
Article
Full-text available
Hypotension is a common occurrence, especially in anesthetized patients and in critical patients suffering from hypovolemia due to shock and sepsis. Hypotension can also occur in normovolemic animals, anesthetized or conscious, under conditions of vasodilation or decreased cardiac function. The main consequence of hypotension is decreased organ per...
Article
Objective To describe and evaluate an ultrasound-guided modified subcostal approach for the transversus abdominis plane (TAP) block in horse cadavers in lateral or dorsal recumbency. Study design Prospective experimental cadaveric study. Animals Study of one preserved foal and eight fresh adult horse cadavers. Methods The lateral and ventral abd...
Article
Objective To evaluate anesthetic conditions and postoperative analgesia with the use of intraoperative constant rate infusions (CRIs) of fentanyl–lidocaine or fentanyl–ketamine in dogs undergoing thoracolumbar hemilaminectomy. Study design Prospective, randomized, blinded, clinical study. Animals A total of 32 client-owned dogs. Methods Dogs wer...
Article
Full-text available
Introduction: While the current tools to assess canine postoperative pain using physiological and behavioural parameters are reliable, an objective method such as the parasympathetic tone activity (PTA) index could improve postoperative care. The aim of the study was to determine the utility of the PTA index in assessing postoperative analgaesia....
Article
Objective To assess cardiopulmonary function in sedated and anesthetized dogs administered intravenous (IV) dexmedetomidine and subsequently administered IV lidocaine to treat the dexmedetomidine-induced bradycardia. Study design Prospective, randomized, crossover experimental trial. Animals A total of six purpose-bred female Beagle dogs, weighin...
Article
Objective To characterize the cardiovascular effects of increasing dosages of norepinephrine (NE) in healthy isoflurane-anesthetized rabbits. Study design Prospective experimental study. Animals A total of nine female ovariohysterectomized New Zealand White rabbits weighing 3.4 ± 0.2 kg (mean ± standard deviation). Methods Rabbits were premedica...
Article
Objective To compare the effectiveness of a paravertebral nerve block vs local portal blocks for laparoscopic closure of the nephrosplenic space in standing sedated research horses. Study design Randomized clinical trial. Animals Twelve horses were randomly allocated to two groups (n = 6 per group), paravertebral block of nerves T18, L1, and L2 o...
Article
Full-text available
Objective: To review the effects of carbon dioxide pneumoperitoneum during laparoscopy, evaluate alternative techniques to establishing a working space and compare this to current recommendations in veterinary surgery. Study Design: Literature review. Sample Population: 92 peer-reviewed articles. Methods: An electronic database search identified hu...
Article
Arterial blood pressure is a common parameter evaluated in conscious and anesthetized veterinary patients for a variety of reasons. Non-invasive blood pressure measurement techniques, such as Doppler ultrasound and oscillometry, are attractive in certain veterinary patients due to their availability and ease of use. The greatest limitation to non-i...
Article
The objective of this study was to evaluate the effect of intra-abdominal pressure (IAP) on cardiorespiratory parameters during pneumoperitoneum with carbon dioxide in domestic rabbits. Six juvenile female New Zealand white rabbits were assigned to randomized sequences of IAP (0, 4, 8 mmHg) in a crossover study. The following parameters were measur...
Article
Arterial blood pressure is a common parameter evaluated in conscious and anesthetized veterinary species. Non-invasive blood pressure measurement techniques, such as Doppler ultrasonic flow detector and oscillometry, are attractive in certain animals due to their availability and ease of use. The greatest limitation to non-invasive blood pressure m...
Article
Objective To determine the dose and cardiopulmonary effects of propofol alone or with midazolam for induction of anesthesia in American Society of Anesthesiologists status ≥ III dogs requiring emergency abdominal surgery. Study design Prospective, randomized, blinded, clinical trial. Animals A total of 19 client-owned dogs. Methods Dogs were sed...
Article
Sympathomimetic drugs mimic the physiological action of the sympathetic nervous system through interaction with adrenergic receptors. These drugs are commonly used to provide cardiovascular support in many veterinary species. Despite their common use, the literature evaluating their effectiveness can be somewhat limited depending on the species. Th...
Article
Full-text available
Background In veterinary medicine, the administration of nonsteroidal anti-inflammatory analgesics (NSAIDs) for the control of postsurgical pain in dogs and cats is common given the anti-inflammatory, analgesic, and antipyretic effects of these drugs. This study compared the serum biochemical changes and postoperative analgesic effects of paracetam...
Article
Objective: To evaluate the performance of an endoscopic 3-mm electrothermal bipolar vessel sealing device (EBVS) intended for single use after multiple use-and-resterilization cycles. Study design: Ex vivo study. Sample population: Eight 3-mm EBVS handpieces. Methods: Handpieces were subjected to a maximum of 15 cycles of testing, including...
Article
Full-text available
Ovarian remnant syndrome (ORS) is a condition resulting from incomplete removal of ovarian tissue during ovariectomy and/or ovariohysterectomy. Single-port laparoscopy (SPL) is an alternative to ventral midline laparotomy for treatment of ORS. Medical records of 13 client-owned female dogs who underwent SPL for the treatment of ORS were retrospecti...
Preprint
Full-text available
Background In veterinary medicine, the administration of nonsteroidal anti-inflammatory analgesics (NSAIDs) for the control of postsurgical pain in dogs and cats is common given the anti-inflammatory, analgesic, and antipyretic effects of these drugs. This study compared the serum biochemical changes and postoperative analgesic effects of paracetam...
Article
Alpha-2 agonists have potent analgesic effects, in addition to their sedative actions. Alpha-2 agonists provide analgesia through any of several routes of administration, including parenteral, oral, epidural or intrathecal and intraarticular, because of spinal and supraspinal actions. Systemic doses are short acting, whereas local administration at...
Article
The degree of analgesia provided by blind techniques for brachial plexus blocks (BPBs) has not been compared in clinical cases undergoing surgery of the thoracic limb. The objective of this study was to evaluate the anesthetic conditions and postoperative analgesia resulting from 3 different BPB local anesthetic techniques in canine patients underg...
Article
Full-text available
OBJECTIVE To evaluate effects of pneumoperitoneum created with warmed humidified CO2 (WHCO2) during laparoscopy on core body temperature, cardiorespiratory and thromboelastography variables, systemic inflammation, peritoneal response, and signs of postoperative pain in healthy mature dogs. ANIMALS 6 mature purpose-bred dogs. PROCEDURES In a randomi...
Article
Objective To compare volumes for epidural injection calculated on body weight or the length from sacrococcygeal space to occipital crest in dogs. Study design Prospective study. Animals A total of 431 dogs weighing mean ± standard deviation (range) 24.6 ± 16.1 (1.3–88.0) kg and with vertebral column length 67.6 ± 38.4 (24.8–119.4) cm. Methods Do...
Article
A 15-year-old, intact, female miniature poodle was presented for further evaluation of a large abdominal mass. Computed tomography was conducted to determine the origin of the mass and 2 large uterine masses were discovered. Ovariohysterectomy was performed and histopathological evaluation revealed a massive uterine Iipoleiomyoma (27 X 17 X 15 cm),...
Article
A laparoscopic-assisted ovariohysterectomy was performed in a 19-year-old intact, female Bengal tiger (Panthera tigris tigris) presented for surgical treatment of pyometra. A multi-port technique was used with intra-corporeal sealing of the ovarian pedicles and extra-corporeal ligation of the uterine vessels and body. The tiger recovered from surge...
Chapter
Local anesthetics can be infiltrated in close proximity to peripheral nerves or nerve endings, applied on the skin as transdermal patches or cream, injected into the epidural/spinal space, and injected into the systemic circulation of an area confined by a tourniquet. The traditional approach for a brachial plexus block is performed by positioning...
Article
Objectives: To describe the ventral spinal nerve rami contribution to the formation of the brachial plexus (BP), and to compare ease of performing and nerve staining between three blind techniques for BP blockade in dogs. Study design: Prospective, randomized, blind study. Animals: A total of 18 dog cadavers weighing 28.2 ± 9.7 kg (mean ± stan...
Article
OBJECTIVE To evaluate the effects of IV diphenhydramine hydrochloride administration on cardiorespiratory variables in anesthetized dogs undergoing mast cell tumor (MCT) excision. DESIGN Randomized, blinded clinical trial. ANIMALS 16 client-owned dogs with MCTs. PROCEDURES In a standardized isoflurane anesthesia session that included mechanical ven...
Article
Full-text available
This study evaluated the cardiovascular effects of a constant rate infusion (CRI) of lidocaine, lidocaine and dexmedetomidine, and dexmedetomidine in dogs anesthetized with sevoflurane at equipotent doses. Treatments consisted of T1-Lidocaine [loading dose 2 mg/kg body weight (BW), IV, and CRI of 100 g/kg BW per min] at 1.4% end-tidal of sevofluran...
Article
A healthy, 9-month-old black Angus bull was presented for elective penile-preputial translocation and caudal epididymectomy. After premedication and induction, general anesthesia was maintained with inhalant anesthetic. Over an hour into the anesthetic period the bull developed severe hyperthermia and hypercapnia that resulted in fatality despite t...
Chapter
In ruminant and swine practice, it is common to combine local anesthetics with restraint methods that may include physical and/or chemical means, to provide a cost-effective and humane alternative to general anesthesia. Local anesthetics can be infiltrated by perineural injection, infiltration at nerve endings in the skin or tissues, injection into...
Article
Objectives: To compare propofol and alfaxalone, with or without midazolam, for induction of anesthesia in fentanyl-sedated dogs, and to assess recovery from total intravenous anesthesia (TIVA). Study design: Prospective, incomplete, Latin-square study. Animals: Ten dogs weighing 24.5 ± 3.1 kg (mean ± standard deviation). Methods: Dogs were r...
Article
The objective of this study was to determine the pharmacokinetics of diphenhydramine (DPH) in healthy dogs following a single i.v. or i.m. dose. Dogs were randomly allocated in two treatment groups and received DPH at 1 mg/kg, i.v., or 2 mg/kg, i.m. Blood samples were collected serially over 24 h. Plasma concentrations of DPH were determined by hig...
Article
Objective: To describe fentanyl pharmacokinetics during isoflurane anesthesia and on recovery from anesthesia with concurrent administration of acepromazine, dexmedetomidine or saline in dogs. Study design: Experimental blinded, randomized, crossover study. Animals: Seven adult hound dogs. Methods: Dogs were administered intravenous (IV) fen...
Article
Objective: To compare isoflurane and propofol for maintenance of anesthesia and quality of recovery in client-owned dogs with intracranial disease undergoing magnetic resonance imaging (MRI). Study design: Prospective, randomized, clinical trial. Animals: Twenty-five client-owned dogs with intracranial pathology, 13 females and 12 males, ages...
Article
The objectives of this study were to establish a reference interval for canine cerebrospinal fluid lactate (CSFL) and to compare CSFL and plasma lactate (PL) concentrations in anesthetized dogs with and without intracranial disease. Using a prospective study, canine blood and cerebrospinal fluid were collected for lactate analysis in 11 dogs with i...
Article
Full-text available
Eight healthy dogs undergoing elective ovariohysterectomy were anesthetized with a standard protocol and received a low-dose medetomidine constant rate infusion during surgery. Cardiorespiratory parameters, including non-invasive cardiac output, were measured at various times. This protocol resulted in acceptable and stable cardiovascular performan...
Article
Objective: To evaluate the cardiopulmonary effects of IV fentanyl administration in dogs during isoflurane anesthesia and during anesthetic recovery with or without dexmedetomidine or acepromazine. Animals: 7 sexually intact male purpose-bred hound-type dogs aged 11 to 12 months. Procedures: Dogs received a loading dose of fentanyl (5 μg/kg, I...
Article
Balanced anesthetic techniques are commonly used in equine patients, and include the combination of a volatile anesthetic with at least one injectable anesthetic throughout the maintenance period. Injectable anesthetics used in balanced anesthesia include the α2-agonists, lidocaine, ketamine, and opioids, and those with muscle-relaxant properties s...
Article
Pain management is a major issue in ruminant practice because many husbandry procedures thought to improve productivity and safety, such as castration and dehorning, are commonly performed with minimal or no analgesia. An increased awareness of ruminant welfare issues has led to more extensive use of analgesic drugs and techniques to decrease pain...
Article
Full-text available
The objective of this study was to compare the effect on the minimum alveolar concentration (MAC) of isoflurane when ketamine was administered either after or without prior determination of the baseline MAC of isoflurane in rabbits. Using a prospective randomized crossover study, 8 adult, female New Zealand rabbits were allocated to 2 treatment gro...
Article
Objectives To compare the effects of sedative doses of acepromazine, xylazine or xylazine/ketamine administered to horses after isoflurane anesthesia on the quality of recovery and anesthesia recovery times. To determine if recovery scores improve after repeated consecutive anesthetic episodes. Study design Prospective, randomized, crossover study....
Article
Full-text available
This study investigated associations between perioperative factors and probability of death and length of hospitalization of mares with dystocia that survived following general anesthesia. Demographics and perioperative characteristics from 65 mares were reviewed retrospectively and used in a risk factor analysis. Mortality rate was 21.5% during th...
Article
Full-text available
The objective of this study was to determine the effects of the administration of a high volume of isotonic crystalloid at a rapid rate on cardiovascular function in normovolemic, isoflurane-anesthetized dogs during induced hypotension.Using a prospective study, 6 adult dogs were induced to general anesthesia and cardiovascular and hematological va...
Article
To compare the determination of cardiac output (CO) via arterial pulse pressure waveform analysis (FloTrac/Vigileo) versus lithium dilution method. Prospective study. University teaching hospital. Six adult dogs. Dogs were instrumented for CO determinations using lithium dilution (LiDCO) and FloTrac/Vigileo methods. Direct blood pressure, heart rat...
Article
Alpha-2 agonists, such as xylazine, clonidine, romifidine, detomidine, medetomidine, and dexmedetomidine, are potent analgesic drugs that also induce physiologic and behavioral changes, such as hypertension, bradycardia, atrioventricular block, excessive sedation and ataxia, all of which can potentially limit their systemic use as analgesics in som...
Article
Observations: A 26-year-old male white rhinoceros (Ceratotherium simum), weighing approximately 2000 kg was anesthetized for an exploratory celiotomy. Sedation was achieved with intramuscular butorphanol (0.04 mg kg(-1)) and detomidine (0.025 mg kg(-1)) and induction of anesthesia with intravenous glyceryl guaiacolate (50 g) and three intravenous...
Article
The effects of lidocaine combined with medetomidine or lidocaine alone on cardiovascular function during anaesthesia and their effects on recovery have not been thoroughly investigated in isoflurane-anaesthetised horses. To determine the effects of an intraoperative i.v. constant rate infusion of lidocaine combined with medetomidine (Group 1) or li...
Article
Full-text available
Objective – To compare cardiac output (CO) measured by use of lithium dilution (LiDCO) and ultrasound velocity dilution (UDCO) in conditions of high, intermediate, and low CO in anesthetized foals. Design – Original prospective study. Setting – University teaching hospital. Animals – Six foals 1–3 days of age (38–45 kg). Interventions – Neonatal fo...
Article
Full-text available
To evaluate the effects of increasing doses of remifentanil hydrochloride administered via constant rate infusion (CRI) on the minimum alveolar concentration (MAC) of isoflurane in cats. 6 healthy adult cats. For each cat, 2 experiments were performed (2-week interval). On each study day, anesthesia was induced and maintained with isoflurane; a cat...
Article
To compare cardiac output (CO) measured by lithium arterial pressure waveform analysis (PULSECO) and CO measured by transpulmonary pulse contour analysis (PICCO) in anesthetized foals, with CO measured by use of lithium dilution (LIDCO) considered the criterion-referenced standard. 6 neonatal (1- to 4-day-old) foals that weighed 38 to 45 kg. Proced...
Article
Standing surgical procedures are performed commonly in horses under sedation. This approach minimises the morbidity/mortality risks associated with general anaesthesia. The use of a medetomidine and morphine combination has not been investigated in horses despite the usefulness of each drug individually. To determine the efficacy of a medetomidine...
Article
Reasons for performing study: Lidocaine single boluses and/or constant rate infusions are commonly administered intraoperatively during inhalant anaesthesia to lower inhalant concentrations, promote or maintain gastrointestinal motility, and potentially supplement analgesia. The benefits of using lidocaine with injectable anaesthesia for field sur...
Article
Current knowledge of drugs administered epidurally has allowed an effective way of providing analgesia for a wide variety of conditions in veterinary patients. Proper selection of drugs and dosages can result in analgesia of specific segments of the spinal cord with minimal side effects. Epidural anesthesia is an alternative to general anesthesia w...
Article
To determine the effectiveness and safety of 2 sedative-analgesic protocols to facilitate assisted ventilation in healthy dogs. 12 healthy dogs. Dogs were randomly assigned to 2 groups. Mean dosages for protocol 1 were diazepam (0.5 mg/kg/h [n = 3 dogs]) or midazolam (0.5 mg/kg/h [3]), morphine (0.6 mg/kg/h [6]), and medetomidine (1.0 microg/kg/h [...
Article
Objective – To determine the effects of IV lactated Ringer's solution at a rate of 10 mL/kg/h in anesthetized dogs on total protein (TP) measurement and calculation of unmeasured anions (UAs) using 2 quantitative methods of acid-base status determination, strong ion gap, and modified base deficit.Design – Prospective clinical study.Animals – Forty-...
Conference Paper
Full-text available
Remifentanil significantly reduces the minimum alveolar concentration (MAC) of enflurane in dogs. This study evaluated the effects of ascending remifentanil constant rate infusions (CRIs) on the MAC of isoflurane in cats. Six adult spayed cats were anaesthetised on two occasions with isoflurane under mechanical ventilation. Esophageal temperature a...
Book
In recent years, a number of important developments have been made in equine anaesthesia and analgesia. These include new methods of monitoring the patient, the availability of new drugs and the implementation of new procedures. This book not only covers all the traditional methods of anaesthesia and recent developments, but it provides students an...
Article
To compare cardiac output (CO) measured by use of the partial carbon dioxide rebreathing method (NICO) or lithium dilution method (LiDCO) in anesthetized foals. Data reported in 2 other studies for 18 neonatal foals that weighed 32 to 61 kg. Foals were anesthetized and instrumented to measure direct blood pressure, heart rate, arterial blood gases,...
Article
To determine the effects of dobutamine, norepinephrine, and vasopressin on cardiovascular function and gastric mucosal perfusion in anesthetized foals during isoflurane-induced hypotension. 6 foals that were 1 to 5 days of age. 6 foals received 3 vasoactive drugs with at least 24 hours between treatments. Treatments consisted of dobutamine (4 and 8...
Conference Paper
Analgesic and systemic effects of two epidural doses of ketamine with or without epinephrine in dogs E Gutierrez-Blanco1, A Navarrete-Jimenez1, A Valverde2, C Sauri-Arceo1, A Ortega-Pacheco1 1Facultad de Medicina Veterinaria y Zootecnia, Universidad Autonoma de Yucatan, Mexico; 2University of Guelph, Canada Epinephrine is used to prolong the durati...
Article
A greater one-horned Asian rhinoceros (Rhinoceros unicornis) presented for presumed ocular trauma to the left eye, with secondary bacterial infection, resulting in severe and progressive corneal ulceration. Following a poor response to medical therapy, the animal was anesthetized for further examination, and a bulbar conjunctival pedicle graft perf...
Article
Lidocaine constant rate infusions (CRIs) are common as an intraoperative adjunct to general anaesthesia, but their influence on quality of recovery has not been thoroughly determined. To determine the effects of an intraoperative i.v. CRI of lidocaine on the quality of recovery from isoflurane or sevoflurane anaesthesia in horses undergoing various...
Article
Objective: This review discusses the different analgesic drugs and routes of administration used in large animals for acute pain management. General guidelines and doses are given to assist in choosing techniques that provide effective analgesia.Etiology: Noxious stimuli are perceived, recognized, and localized by specialized sensory systems locate...
Article
The objective of this study was to assess 2 noninvasive methods of measuring cardiac output (CO) in neonatal foals by comparing results to that of the lithium-dilution method. Ten neonatal foals were anesthetized and CO was manipulated by varying the depth of anesthesia and infusion of dobutamine. Concurrent CO measurements were obtained by lithium...
Article
Full-text available
The objective of this study was to assess 2 noninvasive methods of measuring cardiac output (CO) in neonatal foals by comparing results to that of the lithium-dilution method. Ten neonatal foals were anesthetized and CO was manipulated by varying the depth of anesthesia and infusion of dobutamine. Concurrent CO measurements were obtained by lithium...