Anatomical and Physiological Considerations for Anaesthesia

The risk of anaesthetic-related death has been documented as 1 in 1849 in healthy dogs, whilst in compromised patients (American Society of Anaesthesiologists Grade 3-5) the risk increased to 1 in 75 (Brodbelt et al. 2008). In cats, the same piece of literature found that healthy patients had a risk of 1 in 895, and ASA 3-5 patients saw an increase to 1 in 71. Healthy rabbits were found to have a risk of 1 in 137, and ASA 3-5 rabbits increased to 1 in 14 patients. Given the risks involved with anaesthesia, it is important to fully evaluate a patient presenting for a procedure in order to consider any individual clinical requirements and tailor the anaesthetic plan accordingly. There are a number of genetic or congenital physiological considerations that can have critical implications for anaesthetic management and carry high risk for complications; it is therefore particularly important to adapt the anaesthetic plan accordingly in these patients in order to minimise the risks involved where possible. This article aims to outline the most common genetic or congenital physiological considerations seen in practice and how the anaesthetic plan may be adapted to support the individual needs of the patient.

Brachycephalic breeds

Perhaps the most obvious patient population when discussing physiological changes dictating a change in anaesthetic protocol, brachycephalic breeds of dog are characterised by a skull that is shortened in the rostrocaudal direction, resulting in a short nose. This altered skeletal conformation results in excess soft tissues (relative to the space available) in the upper respiratory tract, with brachycephalic obstructive airway syndrome (BOAS) and increased resistance to inspiratory airflow a common consequence in these breeds (Emmerson 2014). BOAS can cause anaesthesia in these dogs to be challenging; the syndrome is characterised by URT obstruction, with clinical signs including dyspnoea and cyanosis among the more severe symptoms (Emmerson 2014). These breeds are also predisposed to conditions such as gastroesophageal reflux and abnormal ocular conformation predisposing to corneal ulceration, both of which may require specific management as part of the patient’s anaesthetic plan (Poncet et al. 2005, O’Neill et al. 2017).

When formulating an anaesthetic plan for these patients, it is important to tailor the protocols to the individual clinical needs for the dog in front of you. However, there are a number of steps that can be taken to reduce the risk of the more commonly seen complications in this patient population when undergoing anaesthesia.

Clinical Examination:

Dogs should be assessed for evidence of a respiratory abnormality such as dyspnoea, tachypnoea, decreased nasal air flow, or upper respiratory noise (Downing and Gibson, 2018). Any evidence or history of gastrointestinal signs should also be noted.

ASA Grading:

ASA grading promotes consideration of the individual clinical needs for each patient, which may then prompt tailoring of the anaesthetic plan for a proposed procedure. Given the statistical differences in mortality rate quoted above between the various ASA grades, assigning the correct ASA grade is essential to ensure appropriate adaptation of that anaesthetic plan. Jurox have recently updated our detailed ASA chart to reflect current thinking, that a brachycephalic patient presenting with any degree of respiratory or gastrointestinal signs is now suggested to be assigned an ASA grade 3. This is in recognition that these patients may warrant extra caution when presented for anaesthesia given their compromised anatomical and physiological function. If you wish to acquire an updated copy of this ASA chart, please contact your local Jurox representative.

Premedication:

Premedication choices can be challenging, with no widely accepted approach in these patients. Instead, the choice often depends on the patient’s temperament and the severity of concurrent disease, as well as the procedure to be carried out. Acepromazine is favoured by some as having minimal effect on ventilatory function; however, it may exacerbate the risk of airway obstruction through relaxation of pharyngeal muscle tone, and is unlikely to be a potent enough sedative to avoid stress induced respiratory changes in recovery. Acepromazine is also not reversible in recovery, which is widely accepted to be a critical time for BOAS patients; maintenance of a patent airway is essential until the patient has sufficient muscle tone and is alert enough to do this themselves (Downing and Gibson, 2018). Alpha-2 agonists such as medetomidine and dexmedetomidine offer more profound sedation for the induction and recovery periods, with the ability to reverse this sedation partially or completely using atipamezole if required. These sedative agents have also been found to result in shorter time to extubation during recovery following surgery for BOAS (Petruccione et al. 2021). However, caution must be exercised to avoid excessive sedation and consequent excessive hypoventilation, and reduced pharyngeal muscle tone along with increased likelihood of recumbency.

Preoxygenation:

Preoxygenation using 100% oxygen delivered via a facemask for 3 minutes before induction of anaesthesia increases the time to arterial oxygen desaturation following apnoea (McNally et al. 2009). This is likely to be of particular benefit to brachycephalic breeds, in which URT obstruction is common during induction of anaesthesia. Many brachycephalic dogs also have lower arterial oxygen concentrations than is considered normal when conscious and at rest (Hoareau et al. 2012), resulting in desaturation being more commonly seen during periods of apnoea in these patients. These factors mean effective preoxygenation is imperative when anaesthetising this patient population.

Induction agent and intubation:

Given the potential for difficult endotracheal intubation in brachycephalic dogs, it is important to choose an induction agent that gives sufficient duration of action to allow intubation to be achieved successfully. A range of endotracheal tube sizes is essential given the potential of a hypoplastic trachea in these patients, and a good light source and suction catheter, to allow suction of saliva or regurgitated material should also be considered (Downing and Gibson, 2018). Minimising the risk of apnoea is also advised as hypoventilation is not uncommon in brachycephalic dogs (Hoareau et al. 2012), the risk of which is likely to be increased by general anaesthesia. Alfaxalone has been shown to have reduced risk of apnoea in comparison to propofol when given at equipotent doses (Keates and Whittem, 2012), so is an ideal choice of induction agent when administered appropriately in this patient population.

Ocular ulcers:

Corneal lubrication should be administered regularly to reduce the risk of corneal ulceration whilst under general anaesthesia (Downing and Gibson, 2018).

Gastroesophageal reflux:

The oral administration of 1mg/kg omeprazole at least 4 hours prior to induction of anaesthesia has been shown to reduce the incidence of gastroesophageal reflux in anaesthetised patients (Panti et al, 2009).

Sighthounds

Drug choice:

Historically sighthounds have been associated with comparatively delayed recoveries from certain injectable anaesthetic drugs in comparison to other breeds; these drugs include propofol, as well as thiobarbiturates such as thiopental (Martinez et al. 2020, Court, 1999). Initially, the low body fat composition commonly seen in Greyhounds was thought to be the cause for this sensitivity, resulting in limited redistribution of lipophilic anaesthetic products from the brain into peripheral fatty tissues and subsequently delaying the return of consciousness (Court, 1999). More recent studies have suggested that one or more cytochrome P450 enzymes implicated in the metabolism of these drugs may be deficient in Greyhounds and their close relatives (Martinez et al. 2020). In contrast, there is evidence available demonstrating that recoveries following alfaxalone induction are the same in sighthounds as those seen in non-sighthound breeds (Pasloske et al. 2009), which may make alfaxalone a preferred choice of induction agent for these patients.

Hypothermia:

Sighthounds also tend to have a lean body conformation with high surface area to volume ratio, which can predispose the patient to perioperative hypothermia and potentially further prolonged recovery times (Court, 1999, Pottie et al. 2007). Therefore, preventative methods should be taken to minimise heat loss in these patients. A full discussion of such methods is presented in a separate Anaesthesia 1st newsletter article on hypothermia, available to read here.

Species

The perianaesthetic mortality risk is increased for cats and rabbits in comparison to dogs; Brodbelt, 2009 found that rabbits in particular had a considerably higher anaesthetic risk, with 0.17% mortality noted in dogs, 0.24% in cats and 0.73% in rabbits. This is likely to be due to a number of factors:

Induction agent:

In cats, the induction agent chosen can have significant bearing on the subsequent anaesthetic; adverse effects on the quality of recovery from anaesthesia, clinical status and red blood cell physiology have been reported when propofol is administered on consecutive days to induce anaesthesia (Andress et al. 1995). This has been attributed to the relative deficiency of glucuronidation (a stage of metabolism or metabolic conjugation) in cats, resulting in phenolic oxidative injury (and Heinz body formation) in red blood cells. An induction agent such as alfaxalone, which has no toxicity concerns in cats when given repeatedly (Warne et al. 2015, Whittem et al. 2008) may be preferred for these patients, particularly if repeated anaesthetic induction is required.

Intubation:

The feline and rabbit airways are small and more sensitive to trauma and spasm than that of the dog, therefore topical local anaesthesia use to desensitise the larynx prior to intubation is vital in order to help avoid laryngeal trauma and subsequent anaesthetic complications. Intubation in rabbits can be technically challenging; ensuring the pharynx is clear of food material or other debris is important in these patients, as is ensuring the patient is genuinely at stage 3 anaesthesia before attempting to intubate in order to avoid laryngeal stimulation and in turn conscious breath holding, as well as tachycardia, hypertension and increased myocardial oxygen demand. With these technical difficulties in mind for both cats and rabbits, preoxygenation to lower the risk of perianaesthetic hypoxia in these patients is essential.

Hypothermia:

Both rabbits and cats have a high surface area to volume ratio, predisposing the individual to perioperative hypothermia. Perioperative hypothermia has been associated with increased anaesthetic mortality in cats (Redondo et al. 2012).

Fluid overload:

Brodbelt, 2009 found an increased risk of death associated with what may have been overzealous intravenous fluid therapy administration in cats; this is likely to be reflective of the potential for volume overload, given that relatively few practices are likely to be measuring central venous pressure or using fluid pumps to administer intravenous fluids on a regular basis. Therefore careful fluid administration and monitoring is recommended in cats.

Portosystemic shunt

A portosystemic shunt is a vascular anomaly that diverts blood from the abdominal organs to the heart, bypassing the liver. Portosystemic shunts can occur as congenital anomalies, or may develop secondary to liver disease. The liver is responsible for the metabolism of compounds including many anaesthetic agents, so the presence of a portosystemic shunt may result in exacerbated responses to these agents and subsequently increased risk of perianaesthetic mortality. Prior to anaesthesia, patient stabilisation with medical treatment such as lactulose, antibiotics and a low protein diet is recommended to optimise the patient’s condition (De Vries, 2011). Determining the degree of hepatic dysfunction will subsequently allow a tailored approach to the anaesthetic plan for an individual patient; using agents that are reversible such as an alpha-2 agonist means that atipamezole can be used to antagonise if required, but these agents can also have cardiovascular depressant effects so should be used judiciously (De Vries, 2011). Occasionally an opioid alone may provide sufficient sedation; methadone will also provide analgesia, butorphanol will provide sedation only. Opioids may also be antagonised using naloxone.

Undetected abnormalities or disease

Although less prevalent in modern veterinary medicine with the capacity to perform preanaesthetic bloods as well as a thorough clinical examination, it is possible that a congenital abnormality or subclinical disease may remain undiagnosed until the event of a complication at the time of anaesthesia. Examples of a structural abnormality include tracheomalacia, which is an abnormality of the tracheal cartilage inducing excessive collapsibility; this might predispose a patient to tracheal collapse unexpectedly. Examples of subclinical disease may include ‘early’ renal, hepatic or respiratory disease; such conditions may have no observable clinical symptoms and only be detectable as a result of pre-operative bloodwork – which may not routinely be carried out on a young fit patient presenting for an elective procedure, or due to financial constraints. Another example, especially relevant given the risks posted during anaesthesia, is seen in rabbit patients; many rabbits presenting for anaesthesia have been reported to carry subclinical Pasteurella multocida respiratory infections (Flecknell, 1996); this could potentially remain undiagnosed on a preanaesthetic clinical examination, but may increase the likelihood of anaesthetic complications and perioperative mortality. Cardiovascular and respiratory complications represent the major causes of perioperative anaesthetic death documented in small animal literature (Brodbelt et al. 2008); as such the impact of a subclinical respiratory infection, for example, should not be underestimated.

Genetic mutation

MDR1:

The most common genetic mutation affecting anaesthesia is the MDR1 gene; this gene encodes P-glycoprotein (P-gp), which is a drug transporter. P-gp is also a component of the blood brain barrier, and promotes drug excretion through bile and urine (Geyer and Janko, 2012). A mutation to this gene can result in increased sensitivity to certain drugs; this has been documented primarily in herding dogs in the UK (Tappin et al. 2012). Increased sensitivity to acepromazine and butorphanol was observed in MDR1 gene mutation dogs, which experienced a more pronounced and prolonged central nervous system depression compared with normal dogs (Geyer and Janko, 2012). Therefore in cases where the MDR1 mutation is a concern, it is advisable to use agents other than acepromazine and butorphanol; an alpha-2 agonist should not cause the same sensitivity, nor should methadone or buprenorphine - although dose reduction of these agents should still be considered. Warne et al. 2018 report that to mitigate the risk of adverse anaesthetic events, genetic screening for MDR-1 gene mutations should take place in every suspected case prior to elective procedures. Warne et al. 2018 also suggest that diligent monitoring of known cases should take place following sedation, premedication/sedative doses should be reduced by at least 25% and drugs that are antagonisable should be considered.

Breed effects:

There have been anecdotal reports of arrhythmias, hypotension and syncope in Boxer dogs medicated with acepromazine, although these reports appear to be without clear scientific reference. However, this has been attributed to vaso-vagal syncope thanks to the high resting vagal tone that can be seen in Boxers, which may contribute to complications with acepromazine (Murrell, 2007). Consequentially, acepromazine tends not to be a premedicant of choice in this breed, and very low doses (<0.01mg/kg) are recommended along with careful monitoring if it is to be used. Giant breeds of dog are also considered to be ‘more sensitive’ to the effects of acepromazine, which is likely to be a result of relative overdosing of large dogs when dose is calculated according to bodyweight, rather than metabolic body size (Murrell, 2007). Given these sensitivities, it is prudent to remain cautious with acepromazine use in these patient populations.

Summary

An understanding of the physiological alterations that may significantly impact anaesthesia is essential in order to minimise the risk of perianaesthetic mortality in certain patients. Adaptation of the anaesthetic plan for an individual patient to accommodate these alterations can not only reduce the risk of mortality, but also improve a patient’s anaesthetic and surgical experience.

Article by
Dr. Carina Northern
BVSc MRCVS

Veterinary Technical Advisor UK

Originally published: Tuesday, 11th October 2022

References

Andress et al. 1995. The effects of consecutive day propofol anaesthesia on feline red blood cells. Veterinary Surgery 1995 24, 277-282.

Brodbelt et al. 2008. The risk of death: The Confidential Enquiry into Perioperative Small Animal Fatalities. Veterinary Anaesthesia & Analgesia 35, 365-373

Brodbelt, D. 2009 Perioperative mortality in small animal anaesthesia. The Veterinary Journal 182 152-161

Court, M. 1999. Anaesthesia of the sighthound. Clinical Techniques in Small Animal Practice 14(1), 38-43.

De Bries, M. 2011. Anaesthesia and Liver disease: when is the time to start to worry? Veterinary Times, November 2011.

Downing, F. and Gibson, S. 2018. Anaesthesia of brachycephalic dogs. Journal of Small Animal Practice 59(12), 725-733.

Emmerson, T. 2014. Brachycephalic obstructive airway syndrome: a growing problem. BSAVA Journal of Small Animal Practice 55(11), 543-544.

Flecknell, P. 1996. Laboratory animal Anaesthesia. Harcourt Brace & Company, London, 182-189.

Geyer J, Janko C. Treatment of MDR1 mutant dogs with macrocyclic lactones. Current Pharmaceutical Biotechnology. 13(6), 969-86

Hoareau et al, 2012. Evaluation of arterial blood gases and arterial blood pressures in brachycephalic dogs. Journal of Veterinary Internal Medicine 26, 897-904.

Keates, H. and Whittem, T. 2012. Effect of intravenous dose escalation with alfaxalone and propofol on occurrence of apnoea in the dog. Research in Veterinary Science 92(3), 904-906.

Martinez et al. 2020. Pharmacogenomics of poor drug metabolism in Greyhounds: Cytochrone P450 (CYP) 2B11 genetic variation, breed distribution, and functional characterisation. Scientific Reports 10, 69.

McNally et al. 2009. Comparison of time to desaturation between preoxygenated and nonpreoxygenated dogs following sedation with acepromazine maleate and morphine, and induction of anaesthesia with propofol. American Journal of Veterinary Research 70, 1333-1358.

Murrell, J. 2007. Choice of premedicants in cats and dogs. In Practice 29, 100-106.

O’Neill et al 2017. Corneal ulcerative disease in dogs under primary veterinary care in England: epidemiology and clinical management. Canine Genetics and Epidemiology 4, 5.

Panti et al. 2009. The effect of omeprazole on oesophageal pH in dogs during anaesthesia. The Journal of Small Animal Practice 50, 540-544.

Pasloske et al. 2009. Plasma pharmacokinetics of alfaxalone in both premedicated and unpremedicated Greyhound dogs after single, intravenous administration of Alfaxan at a clinical dose. Journal of Veterinary Pharmacology and Therapeutics, 32(5), 510–513.

Petruccione et al. 2021. Comparison between dexmedetomidine and acepromazine in combination with methadone for premedication in brachycephalic dogs underdoing surgery for brachycephalic obstructive airway syndrome. Veterinary Anaesthesia and Analgesia 2021 48, 305-313.

Poncet et al. 2005. Prevalence of gastrointestinal tract lesions in 73 brachycephalic dogs with upper respiratory syndrome. The Journal of Small Animal Practice 46, 273-279.

Pottie et al. 2007. Effect of hypothermia on recovery from general anaesthesia in the dog. Australian Veterinary Journal 85(4), 158-62.

Redondo et al. 2012. Retrospective study of the prevalence of postanaesthetic hypothermia in cats. Veterinary Record 170(8), 206.

Tappin et al. 2012. Frequently of the mutant MDR1 allele in dogs in the UK. Veterinary Record 171, 72.

Warne et al. 2015. A review of the pharmacology and clinical application of alfaxalone in cats. The Veterinary Journal 203, 141-148.

Warne et al. 2018. Standards of care: Anaesthesia guidelines for dogs and cats. Australian veterinary journal. 96(11): 413-427.

Whittem et al. 2008. The pharmacokinetics and pharmacodynamics of alfaxalone in cats after single and multiple intravenous administration of Alfaxan at clinical and supraclinical doses. Journal of Veterinary Pharmacology and Therapeutics 31, 571-579.

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What's the Point? Peripheral Intravenous Cannulation.

Peripheral venous cannulation is a common invasive procedure in small animals, but what are the best-practice insertion techniques and what can we do to avoid complications?

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Rabbit Anaesthesia – Understanding Your Patient.

How does the anatomy, physiology, behaviour and response to drugs affect your decision making when anaesthetising the rabbit patient?

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Paper summary: Heated intravenous fluids alone fail to prevent hypothermia in cats under general anaesthesia.

In this summary of a paper by Jourdan et al (2017) we examine the common practice of warming intravenous fluids and the effect on patient temperature.

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Watch the induction and intubation of a brachycephalic.

Induction of anaesthesia and intubation of a brachycephalic dog with Matt Gurney.

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Considerations for anaesthesia of the brachycephalic dog.

In this article Matt Gurney discusses the induction of anaesthesia and intubation of the brachycephalic patient.

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Paper summary: The effect of omeprazole on oesophageal pH in dogs during anaesthesia

This summary of a publication by Panti et al., examines the effect of orally administered omeprazole on gastro-oesophageal reflux in the anaesthetised dog.

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How does a syringe driver benefit your patients?

Syringe drivers are becoming increasingly commonplace in modern veterinary practice and are a useful tool for multiple applications. This article looks at the science behind constant rate infusions and the basics of syringe driver use.

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Paper summary: Pet owner opinions about anaesthesia, pain and surgery in small animals

In this paper we explore perceptions and opinions of Canadian pet owners about anaesthesia, pain and surgery in small animals.

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Achieving Safer Anaesthesia with ASA and Joanne Michou MA VetMB DipECVAA MRCVS

How can a Veterinary version of the ASA Physical Status Classification help you achieve safer anaesthesia? To find out how watch our webinar.

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Paper summary: ASA classification and risk of anaesthetic related death in dogs and cats.

This scientific paper assessed whether the American Society of Anesthesiologists (ASA) Physical Status Classification correlated with the risk of anaesthetic death in dogs and cats.

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A retrospective comparison of two analgesic strategies after uncomplicated tibial plateau levelling osteotomy in dogs.

In this review we summarise a publication by Bini (2018) examining two protocols for the administration of methadone following TPLO surgery in dogs.

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Practical Acute Pain Assessment

In this summary of acute pain assessment, Carl Bradbrook examines why we should be monitoring patients for pain and looks at the commonly used scoring systems.

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Alfaxan for the maintenance of anaesthesia: Peer reviewed clinical papers.

In this article we have identified the key clinical peer reviewed papers to support the use of Alfaxan for maintenance of Anaesthesia in Cats and Dogs.

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TIVA or not? (Total intravenous anaesthesia).

In this article the Jurox UK Technical Team discuss the use of intravenous agents to maintain anaesthesia in the dog and cat.

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Benzodiazepines - can they help reduce anaesthesia related side effects?

In part 4 of this series on premedicant agents we examine the pros and cons of benzodiazepines.

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Paper summary: Effect of benzodiazepines on the dose of alfaxalone needed for endotracheal intubation in healthy dogs

This paper examined whether a benzodiazepine, administered as a co-induction agent with alfaxalone, improved endotracheal intubation, and reduced the dose of alfaxalone, in the dog

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Putting methadone in its place in your pain management.

In this article we examine why methadone could be considered the analgesic of choice for many of our patients and understand its importance in modern veterinary medicine. The article includes a link to a downloadable summary sheet.

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Purr-fecting Pain Management

In this article summary we examine which of the two opioids, buprenorphine or butorphanol, provides the most appropriate analgesia following ovariohysterectomy in the cat.

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Perspectives on Premeds - Phenothiazines: from Mental Health to Premedication

In this article from the Perspectives on Premeds series, Karen takes us through the properties and uses of phenothiazines in modern veterinary practice.

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Methadone with Acepromazine - when is enough, enough?

This study looks at the effects of three methadone doses combined with acepromazine on sedation and some cardiopulmonary variables in dogs.

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Time: is 30 minutes long enough?

This recent study examined whether the application of EMLA cream, for 30 or 60 minutes, would be a useful tool to improve patient compliance prior to intravenous cannula placement in the veterinary clinical practice setting.

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Caesarean Section Survival Guide. Part 2: Anaesthetic Protocol Selection & Peri-operative Considerations.

In this second instalment of the 2-part article, we explore premedication, induction, maintenance & monitoring, recovery and analgesia for the Caesarean section patient.

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Buprenorphine: it’s not all static in rabbits

Opioids are well known for causing gastrointestinal stasis in mammalian species. This recent paper examined the effects of a single high dose of buprenorphine on the rabbit gastrointestinal tract using non-invasive imaging techniques.

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Caesarean Section Survival Guide. Part 1: Physiology & Pre-anaesthetic Considerations.

In the first instalment of this 2-part review Karen examines the physiological changes that occur during pregnancy and how those adjustments can affect the selection of anaesthetic protocols for the increasingly common Caesarean section.

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No leeway for the spay: A comparison between methadone and buprenorphine for perioperative analgesia in dogs undergoing ovariohysterectomy.

This recent paper compares post-operative pain scores and requirement for rescue analgesia following premedication with methadone or buprenorphine, in combination with acepromazine or medetomidine, in 80 bitches undergoing ovariohysterectomy.

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Cardiac arrest - the human factor

Cardiac arrest in dogs and cats is, thankfully, relatively rare. However, when it does happen it can have devastating consequences for the animal, owner and the veterinary team. This study examined the common causalities leading up to a cardiac arrest with the aim of changing protocols to improve outcomes.

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Are you Using Safety Checklists in your Practice?

In this article, Carl focuses on the benefits of introducing a safety checklist in practice to reduce patient morbidity, mortality and to improve communication between members of the veterinary team. The article contains links to the AVA safety checklist as well as a link to a customisable list that you can adapt to your practice needs.

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Paper Summary - Effects of alfaxalone, thiopental, propofol and diazepam on laryngeal motion in healthy dogs

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The Big Chill - Temperature Management in Sedated and Anaesthetised Patients

The effects of hypothermia are very far reaching throughout the peri-anaesthetic process. In this article, James takes us through the interesting mechanisms of body cooling and warming, the clinical relevance of hypothermia and what we can do to prevent it.

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Keeping the Finger on the Pulse - Nuances in CV Monitoring

All patients are exposed to the risks associated with general anaesthesia. Continuously monitoring anaesthetised patients maximises patients safety and wellbeing. In this article, Dan takes us through the common monitoring techniques that provide information about the cardiovascular status of your patient.

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Effect of Maropitant on Isoflurane Requirements & Postoperative Nausea & Vomiting

Despite being widely recognized in humans, postoperative nausea and vomiting (PONV), and the role of maropitant in reducing inhalational anaesthetic requirements have been poorly documented in dogs. This recent study evaluates PONV and isoflurane requirements after maropitant administration during routine ovariectomy in bitches.

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New! Alfaxan® Multidose Now Available

We are happy to announce we have enhanced our anaesthesia and analgesia portfolio with the introduction of Alfaxan®Multidose for dogs, cats and pet rabbits.

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Sevoflurane requirement in dogs premedicated with medetomidine and butorphanol

Little information is available about the effect that different doses of medetomidine and butorphanol may have when using sevoflurane for maintenance of anaesthesia in dogs. This recent study evaluates heart rate and median sevoflurane concentration required at different dose rates.

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Capnography II - What happened to the elephants? A summary of abnormal traces

In this second article of the capnography series, James provides a guide to a few of the most common traces that you will encounter during surgery. Scroll to the end of the article to download a printable capnography cheatsheet.

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Pain, what a Pain! (Part 2) – Practical Tips On How To Perform Dental Nerve Blocks In Companion Animal Practice

In this second article of the Pain, what a Pain! series, Dan takes us through the LRA techniques associated with dental and oral surgery. In this article, you will find practical tips and pictures on common dental nerve blocks as well as safety concerns to consider.

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Peri-anaesthetic mortality and nonfatal gastrointestinal complications in pet rabbits

This recent retrospective study looks at the cases of 185 pet rabbits admitted for sedation or general anaesthetic and evaluates the incidence and risk factors contributing to peri-anaesthetic mortality and gastrointestinal complications.

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Pain, what a Pain! How Locoregional Anaesthesia can Improve the Outcome and Welfare of Veterinary Patients (Part 1)

In this first article out of a series of two, Dan takes us through an introduction and practical tips for appropriate local anaesthesia delivery. Find out why these anaesthesia techniques, that are well recognised in human medicine, have seen an increase in popularity in veterinary medicine over the recent years

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Perspectives on Premeds – Opioids

Perspectives on Premeds is a series of articles touching on different pharmacological, physiological and clinical aspects of pre-anaesthetic medication. This second article aims to provide a refresher on opioids.

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Effects of Dexmedetomidine with Different Opioid Combinations in Dogs

Read the highlights of a recently published research paper that evaluates cardiorespiratory, sedative and antinociceptive effects of dexmedetomidine alone and in combination with morphine, methadone, meperidine, butorphanol, nalbuphine and tramadol.

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Preoxygenation Study Highlights

This study evaluates the effectiveness of two methods of preoxygenation in healthy yet sedated dogs and the impact of these methods on time taken to reach a predetermined haemoglobin desaturation point (haemoglobin saturation (SpO2) of 90%) during an experimentally induced period of apnoea.

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