Analgesia for anesthetized patients

Perioperative Pain Management for Mastectomy in Dogs: A Narrative Review

Mammary tumours are the most common neoplasia in adult female dogs. Mastectomy leads to moderate to severe pain. Effective pain management is crucial in veterinary medicine. This review outlines analgesic techniques for managing perioperative pain in dogs undergoing mastectomy. A literature search on dog mastectomy analgesia was conducted from January 2001 to January 2025. Pre-emptive meloxicam reduces postoperative cardiovascular changes without affecting renal function. When combined with gabapentin, it lowers the need for rescue analgesic opioids, similar to robenacoxib. With regard to tramadol, it offers contrasting analgesia in the studies considered when used alone, while its effect appears enhanced when used in combination with meloxicam/dipyrone. However, methadone provides superior pain control, especially when given preoperatively or intraoperatively. The combination of ketamine, lidocaine, and maropitant enhances pain management, while fentanyl, alone or with lidocaine and ketamine, is effective for intraoperative pain control. Local infiltration with lidocaine/bupivacaine provides effective pain control, and devices like Comfont-in® or WSC facilitate this process. Tumescent anaesthesia using lidocaine/ropivacaine allows for extensive infiltration of the mammary gland. Epidural analgesia, paravertebral blocks, and TAP blocks are beneficial in multimodal protocols. Transdermal patches containing fentanyl/buprenorphine offer prolonged analgesia, while electroacupuncture can help reduce the need for rescue analgesics. Multimodal analgesic protocols are crucial for effective pain management in dog mastectomy surgeries, minimising the need for rescue opioids.

The Welfare of Fighting Dogs: Wounds, Neurobiology of Pain, Legal Aspects and the Potential Role of the Veterinary Profession

Simple Summary

Dog fights are cruel and harmful events which have a clear impact on animal welfare. For this reason, many countries have banned these events via statute. However, in some regions of the world they are still legal. Moreover, the enforcement of legal bans can be problematic in countries where they are illegal, and they may still occur. This article provides background information on dog fighting and the welfare implications of it. This includes consideration for the pain inflicted, and its mechanisms of perception and recognition. It also analyzes the injuries and emotions experienced by the animals and considers the profile of the breeders and handlers involved in the activity. Since welfare concerns often extend beyond the animals’ fighting lives, a discussion around the possibilities of reintroduction into suitable environments for these animals is also made. Finally, attention is turned to the role that veterinarians can and should play in dealing with these issues of welfare.

Abstract

Throughout history it has been common to practice activities which significantly impact on animal welfare. Animal fighting, including dogfighting, is a prime example where animals often require veterinary care, either to treat wounds and fractures or to manage pain associated with tissue and where death may even result. Amongst the detrimental health effects arising are the sensory alterations that these injuries cause, which not only include acute or chronic pain but can also trigger a greater sensitivity to other harmful (hyperalgesia) or even innocuous stimuli (allodynia). These neurobiological aspects are often ignored and the erroneous assumption made that the breeds engaged in organized fighting have a high pain threshold or, at least, they present reduced or delayed responses to painful stimuli. However, it is now widely recognized that the damage these dogs suffer is not only physical but psychological, emotional, and sensory. Due to the impact fighting has on canine welfare, it is necessary to propose solution strategies, especially educational ones, i.e., educating people and training veterinarians, the latter potentially playing a key role in alerting people to all dog welfare issues. Therefore, the aim of this review is to describe the risk factors associated with dogfighting generally (dog temperament, age, sex, nutrition, testosterone levels, environment, isolation conditions, socialization, education, or training). A neurobiological approach to this topic is taken to discuss the impact on dog pain and emotion. Finally, a general discussion of the format of guidelines and laws that seek to sanction them is presented. The role that veterinarians can play in advancing dog welfare, rehabilitating dogs, and educating the public is also considered.

2022 AAHA Pain Management Guidelines for Dogs and Cats

These updated guidelines present a practical and logical approach to the assessment and management of acute and chronic pain in canine and feline patients. Recognizing pain is fundamental to successful treatment, and diagnostic guides and algorithms are included for assessment of both acute and chronic pain. Particularly for chronic pain, capturing owner evaluation is important, and pain-assessment instruments for pet owners are described. Expert consensus emphasizes proactive, preemptive pain management rather than a reactive, "damage control" approach. The guidelines discuss treatment options centered on preemptive, multimodal analgesic therapies. There is an extensive variety of pharmacologic and nonpharmacologic therapeutic options for the management of acute and chronic pain in cats and dogs. The guidelines include a tiered decision tree that prioritizes the use of the most efficacious therapeutic modalities for the treatment of acute and chronic pain.

Effects of morphine on histamine release from two cell lines of canine mast cell tumor and on plasma histamine concentrations in dogs with cutaneous mast cell tumor

OBJECTIVE

To determine the effects of morphine on histamine release from 2 canine mast cell tumor (MCT) cell lines and on plasma histamine concentrations in dogs with cutaneous MCTs.

ANIMALS

10 dogs with cutaneous MCT and 10 dogs with soft tissue sarcoma (STS).

PROCEDURES

The study consisted of 2 phases. First, 2 canine MCT cell lines were exposed to 3 pharmacologically relevant morphine concentrations, and histamine concentrations were determined by an ELISA. Second, dogs with MCT or STS received 0.5 mg of morphine/kg, IM, before surgery for tumor excision. Clinical signs, respiratory rate, heart rate, arterial blood pressure, rectal temperature, and plasma histamine concentrations were recorded before and 5, 15, 30, and 60 minutes after morphine administration but prior to surgery. Data were compared by use of a 2-way ANOVA with the Sidak multiple comparisons test.

RESULTS

In the first phase, canine MCT cell lines did not release histamine when exposed to pharmacologically relevant morphine concentrations. In the second phase, no differences were noted for heart rate, arterial blood pressure, and rectal temperature between MCT and STS groups. Plasma histamine concentrations did not significantly differ over time within groups and between groups.

CONCLUSIONS AND CLINICAL RELEVANCE

No significant changes in histamine concentrations were noted for both in vitro and in vivo study phases, and no hemodynamic changes were noted for the in vivo study phase. These preliminary results suggested that morphine may be used safely in some dogs with MCT.

Antinociceptive and analgesic effect of continuous intravenous infusion of maropitant, lidocaine and ketamine alone or in combination in cats undergoing ovariohysterectomy

Background

Multimodal analgesia consists of the combination of analgesic drugs at low doses to act in different places along the path of pain. Studies with continuous infusion of analgesic drugs in cats are not common. This study aimed to evaluate the analgesic effect of maropitant, lidocaine and ketamine alone or in combination (intravenous bolus + subsequent continuous intravenous infusion) in the management of acute postoperative pain in cats undergoing ovariohysterectomy. Seventy healthy cats undergoing an ovariohysterectomy received a standard anesthetic protocol consisting of acepromazine and morphine, propofol (anesthesia induction), and isoflurane (anesthesia maintenance). The animals were stratified into seven groups (n = 10 in each group): control (CG), maropitant (MG), lidocaine (LG), ketamine (KG), maropitant + lidocaine (LMG), maropitant + ketamine (KMG), and maropitant + lidocaine + ketamine (LKMG). All drugs were injected first as an intravenous bolus and then by continuous intravenous infusion. During surgery, esophageal temperature, respiratory rate, heart rate, oxygen saturation, expired isoflurane concentration, and partial pressure of carbon dioxide at the end of expiration were evaluated at 7 time points. Postoperative pain was evaluated for 6 h after extubation using the visual analogue scale and the UNESP-Botucatu multidimensional composite pain scale for assessing postoperative pain in cats.

Results

Adverse effects related to maropitant, lidocaine and ketamine infusion were not observed. Pain scores were lower in the MG, KG and LG groups when compared to the CG group using both scales. Although pain scores were also lower in all combination groups than CG, more animals in these groups required rescue analgesia compared to MG. This indicates that the postoperative analgesic effect of all drugs, either alone or in combination, confers analgesia, although the combinations did not promote greater analgesia.

Conclusions

Continuous intravenous infusion of maropitant, lidocaine, and ketamine alone induces postoperative analgesic effect in cats undergoing ovariohysterectomy, but combinations of these drugs did not increase the analgesic effect. No adverse effect was observed with any drug or their combination.

Meloxicam administration in the management of postoperative pain and inflammation associated with caesarean section in beef heifers: Evaluation of reproductive parameters

Post-operative pain and inflammation are normal physiological reactions to caesarean section. Their management in cattle have rarely been investigated. This surgical procedure negatively affects reproductive function with, for example, a reduction in fertility resulting in an increase in calving interval. In this multicenter clinical trial, the objective was to evaluate the impact on reproductive performance of meloxicam injected before caesarean section to manage post-operative pain and inflammation. Meloxicam is a non-steroidal anti-inflammatory drug. One hundred and twenty-seven Charolais heifers (n = 127) were recruited from 47 farms in six French veterinary practices in the Burgundy region. The heifers underwent a non-elective standardized caesarean section operation. Heifers were randomly assigned to one of two groups: meloxicam (n = 66), intravenous meloxicam injection before surgery, or control (n = 61). Reproductive performance and health information were recorded from the time of the caesarean section to the next calving or to culling. In our study, meloxicam administration before caesarean section had no effect on the incidence of retained placenta (18.2% of treated vs 25.0% of control cows, p = 0.35). The pregnancy rate was higher in treated than in control cows (83.1% vs 67.8%, p = 0.04 after multivariate analysis) and a survival analysis showed that the median calving interval was 35 days shorter in the meloxicam (t_50% = 417 days) compared to the control group (t_50% = 452 days, p = 0.05). A trend was also observed for culling rate to be lower in treated (4.7%) compared to control cows (13.3%, p = 0.09). In conclusion, this study suggests that there is a beneficial effect of meloxicam administration before caesarean section on reproductive performance in Charolais heifers.

ACVIM consensus statement on pancreatitis in cats

Background

Pancreatitis in cats, although commonly diagnosed, still presents many diagnostic and management challenges.

Objective

To summarize the current literature as it relates to etiology, pathogenesis, diagnosis, and management of pancreatitis in cats and to arrive at clinically relevant suggestions for veterinary clinicians that are based on evidence, and where such evidence is lacking, based on consensus of experts in the field.

Animals

None.

Methods

A panel of 8 experts in the field (5 internists, 1 radiologist, 1 clinical pathologist, and 1 anatomic pathologist), with support from a librarian, was formed to assess and summarize evidence in the peer reviewed literature and complement it with consensus clinical recommendations.

Results

There was little literature on the etiology and pathogenesis of spontaneous pancreatitis in cats, but there was much in the literature about the disease in humans, along with some experimental evidence in cats and nonfeline species. Most evidence was in the area of diagnosis of pancreatitis in cats, which was summarized carefully. In contrast, there was little evidence on the management of pancreatitis in cats.

Conclusions and Clinical Importance

Pancreatitis is amenable to antemortem diagnosis by integrating all clinical and diagnostic information available, and recognizing that acute pancreatitis is far easier to diagnose than chronic pancreatitis. Although both forms of pancreatitis can be managed successfully in many cats, management measures are far less clearly defined for chronic pancreatitis.

Postoperative evaluation of analgesia promoted by the use of dexmedetomidine alone and associated with morphine as an intramuscular pre-anesthetic medication in bitches submitted for ovariohysterectomy

Abstract This study aimed to evaluate the postoperative analgesic efficacy of dexmedetomidine alone and when associated with morphine in patients under general inhalational anesthesia with isoflurane and undergoing elective ovariohysterectomy (OH). Twenty healthy bitches were selected via physical and laboratory examinations. Prior to the study, they underwent a 24-h period of adaptation to the environment and observers. They were then randomly divided into two groups: the dexmedetomidine group receiving a dose of 10 μg/kg, and dexmedetomidine group (10 μg/kg) associated with morphine receiving a dose of 0.3 mg/kg, administered via the intramuscular route. Thereafter, patients were induced with propofol and maintained with isoflurane diluted in 100% oxygen administered through a calibrated vaporizer. To verify postoperative analgesia, pain assessments were performed using the modified Glasgow (EGM) and Melbourne (EM) scales. For sedation assessment, the Dobbins scale was used at different times: before the administration of pre-anesthetic medication (T0) and at another six times in the postoperative period, 1 (T1), 2 (T2), 4 (T3), 8 (T4), 12 (T5), and 24 (T6) h after orotracheal extubation. No statistical differences were observed between groups in the scales according to Dunn’s Kruskal-Wallis post hoc test, and between the times a statistical difference was noticed by the Friedman test (p<0.05) for the EGM and EM scale scores, but there was no need for analgesic rescue. Therefore, we found that isolated dexmedetomidine and morphine produced adequate analgesic effects in the postoperative period of bitches submitted for OH.

Review of different methods used for clinical recognition and assessment of pain in dogs and cats

In light of the need to perform surgical techniques and the importance of animal welfare because of acute pain, the objectives of the veterinary anaesthetists are to manage muscle relaxation and adequate analgesia in order to conserve a balance in the autonomic nervous system, enhance the action of the parasympathetic system in the face of the emerging action of the sympathetic portion provoked by the surgeon, and maintain a balance among them. The aim of the present review is to describe different evaluation criteria for acute pain using unidimensional and multidimensional scales, correlating these findings to parasympathetic tone activity (PTA) and bispectral index (BIS) assessment, to conduct an objective evaluation of pain that patients (dog or cat) perceives, in order to administrate an adequate analgesic treatment in each case. In conclusion, this integral, objective evaluation will allow veterinarians – especially anaesthesiologists – to improve the management of pain in the patients.

Nonanesthetic Effects of Ketamine: A Review Article

Ketamine is considered a dissociative anesthetic medication, and it is commonly administered by a parenteral route. It works mainly by blocking the N-methyl-D-aspartate receptor. It inhibits the voltage-gated Na and K channels and serotonin and dopamine reuptake; also, it affects specific receptors, such as α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, kainate, and aminobutyric acid A receptors. Ketamine appears to have particular mechanisms that are potentially involved during analgesic induction, including enhancing of descending inhibition and antiinflammatory effects. More recently, it has been shown that ketamine has potential in clinical practice for the management of chronic pain, cognitive function, depression, acute brain injury, and disorders of the immune system.

Management of acute pancreatitis in dogs: a critical appraisal with focus on feeding and analgesia

Knowledge about acute pancreatitis has increased recently in both the medical and veterinary fields. Despite this expansion of knowledge, there are very few studies on treatment interventions in naturally occurring disease in dogs. As a result, treatment recommendations are largely extrapolated from experimental rodent models or general critical care principles. General treatment principles involve replacing fluid losses, maintaining hydrostatic pressure, controlling nausea and providing pain relief. Specific interventions recently advocated in human medicine include the use of neurokinin-1 antagonists for analgesia and early interventional feeding. The premise for early feeding is to improve the health of the intestinal tract, as unhealthy enterocytes are thought to perpetuate systemic inflammation. The evidence for early interventional feeding is not supported by robust clinical trials to date, but in humans there is evidence that it reduces hospitalisation time and in dogs it is well tolerated. This article summarises the major areas of management of acute pancreatitis in dogs and examines the level of evidence for each recommendation.

Globe penetration in a cat following maxillary nerve block for dental surgery

CLINICAL SUMMARY

Dental treatment was carried out in an 8.5-year-old castrated male domestic shorthair cat found to have tooth resorption. Right mandibular, and right and left maxillary nerve blocks were administered using a 1 ml syringe attached to a 25 G x 5/8 inch needle and an intraoral technique. The following day the cat displayed blepharospasm of the right eye. The ocular signs progressed and 5 days later an ophthalmologist confirmed a blind, glaucomatous right eye. It was suspected that the eye had suffered a penetrating injury during dental surgery. Enucleation of the right eye was performed and gross and histopathological examination revealed a penetrating wound consistent with a needle tract injury.

PRACTICAL RELEVANCE

Complications arising from veterinary dental regional anaesthesia appear to be rare; however, it may be that they are under-reported. This case report highlights the risks involved and reviews the safest and most efficacious regional anaesthesia technique for the feline maxilla.