Postoperative Pain In Dogs Research Articles

A systematic review of analgesia practices in dogs undergoing ovariohysterectomy

Aim:This was a systematic review conducted to evaluate the analgesic drugs and techniques used in the management of pain in dogs undergoing ovariohysterectomy.Materials and Methods:Systematic searches in PubMed, Google Scholar, and ScienceDirect were conducted for peer-reviewed articles written in English and published from 1995 to 2015. The key search words were dogs, ovariohysterectomy, pain, and analgesics. This was followed by a manual search of the references within the primary data sources. Inclusion and exclusion of studies and data extraction were performed independently by two reviewers. All randomized studies evaluating the effects of analgesics during ovariohysterectomy in dogs were included.Results:A total of 31 trials met the criteria and were, therefore, included in the study. Data on the type of analgesic drugs used, the technique of administration, and the need for rescue analgesia were extracted from the papers. Individual analgesic protocols were used in 83.9% of the studies compared to multimodal drug therapy, which was used in 16.1% of the studies. Opioids were used in 39.0% of studies, nonsteroidal anti-inflammatory drugs (NSAIDs) in 19.4%, a combination of NSAIDs and opioids in 19.4%, local analgesics in 6.5%, and acupuncture in 3.2% of the studies. Drug administration was done using three approaches that included pre-operative (64.5%), post-operative (22.6%) as well as combined pre- and post-operative approach (12.9%). In 77.4% of the studies, administration of analgesics was done once, while in 12.9%, it was done as a 72-h post-operative course. 24-h and 48-h courses of post-operative pain therapy were done in 6.5% and 3.2% of the studies, respectively. About 57% of the dogs in the control groups required rescue analgesia as compared to 21.6% in the single and 11.3% in multimodal drug therapy groups. The requirement for rescue analgesics was highest in dogs treated using acupuncture (43.8%) and lowest in dogs treated using NSAID-opioid combination (8.6%). Fewer dogs among those that received pain medication preoperatively and postoperatively required rescue analgesia compared to those in groups given drugs before and after surgery only. More dogs (26.4%) among those given analgesics only once postoperatively required rescue analgesia as compared to those that received analgesics daily for 72 h (4.4%).Conclusions:This study provides evidence that opioids are the mainstream analgesic drugs used in managing acute post-operative pain in dogs’ post-ovariohysterectomy. In addition, multimodal drug therapy, particularly, NSAID-opioids combination is more effective for pain management than single drug administration. Administering analgesics both before and after surgery is associated with better outcomes and so is a protracted course of post-operative pain therapy. Although these practices should be encouraged, controlled studies should be conducted to conclusively determine the best practices for pain management in dogs undergoing ovariohysterectomy.

Comparison of different tools for pain assessment following ovariohysterectomy in bitches

BACKGROUND: Accurate identifying and assessment of the degree of pain that the animal is suffering can be a challenge, and, control of painful condition is becoming an increasingly important part of veterinary medicine. OBJECTIVES: This study was carried out to compare different tools for postoperative pain assessment in bitches. METHODS: Ten adult mixed breed bitches were selected and randomly divided into two equal treatment and control groups. Anaesthesia was premedicated with acepromazine (0.03 mg/kg, IM) and induced with Sodium thiopental (6-10 mg/kg, IV). Halothane was used for maintenance of the anesthesia. Ovariohysterectomy performed in the two groups. Treatment group received 3 mg/kg of tramadol intramuscularly (i.m.) and control group received normal saline (equal volume with tramadol, i.m.) before the anesthetic induction. After operation the injections of tramadol and normal saline were repeated for every 6 hours in 7 days. The animals were monitored at hour 2, 3 and 4 after each injection and they were scored for signs of pain by two trained assessors who were blinded to the groups. The measured variables were pain assessment with different methods including Simple Descriptive Scale (SDS), Visual Analogue Scale (VAS), and University Melbourne Pain Scale (UMPS). Duration of anesthesia and duration of surgery, were also recorded. RESULTS: There were no significant differences between the two groups in regard to analgesia that were measured based on VAS and SDS methods, but in UMPS method, analgesia was significantly better in treatment group. Among simple clinical criteria body temperature and respiratory rate did not show any significant alterations, but heart rate had significant changes between the groups. CONCLUSIONS: The ability to quantify the degree of pain experienced by animals is an important aspect in the assessment of animal welfare; in addition, we concluded, that the great challenge for the veterinarians is the evaluation of postoperative pain in dogs

Effects of a transdermal lidocaine patch on indicators of postoperative pain in dogs undergoing midline ovariohysterectomy.

OBJECTIVE To determine the effects of a transdermal lidocaine patch (TLP) on indicators of postoperative pain in healthy dogs following ovariohysterectomy. DESIGN Randomized, blinded controlled trial. ANIMALS 40 healthy shelter-owned female dogs admitted to a student surgery program for ovariohysterectomy. PROCEDURES Dogs were randomly assigned to receive after ovariohysterectomy a 5-cm-wide strip of TLP applied topically on both sides of the incision, for the full length of the incision and a wound dressing (n = 19) or a placebo patch (nonmedicated wound dressing; 21). All dogs underwent midline ovariohysterectomy. Immediately afterward, dogs received 2 IM morphine injections, carprofen (SC, q 12 h for 2 days), and the assigned patch (left in place for 18 hours). Postoperative comfort was evaluated by use of the short form of the Glasgow Composite Measures Pain Scale and serum cortisol concentrations measured prior to premedication and 1, 2, 4, 6, 8, 10, and 18 hours after surgery. RESULTS No significant difference in pain scores or serum cortisol concentrations was identified between dogs that received the TLP and dogs that received a placebo patch after ovariohysterectomy. CONCLUSIONS AND CLINICAL RELEVANCE The TLP provided no additional analgesic benefit to dogs treated concurrently with recommended doses of morphine and carprofen following ovariohysterectomy. Additional studies are needed to investigate whether similar results might be achieved in dogs treated concurrently with other analgesics. (J Am Vet Med Assoc 2017;250:1140-1147).

Effect of intrafragmentary bupivacaine (haematoma block) on analgesic requirements in dogs undergoing fracture repair

ObjectiveTo test the efficacy of intraoperative intrafragmentary administration of bupivacaine (haematoma block) in controlling postoperative pain in dogs undergoing osteosynthesis of long-bone isolated diaphyseal fractures. Study designRandomized, ‘blinded’, placebo-controlled, prospective study. AnimalsA total of 23 client-owned dogs with isolated long-bone fractures. MethodsDogs were allocated randomly to two groups: bupivacaine group (B) or placebo group (P). Group B dogs (n = 11) were administered an intraoperative intrafragmentary injection of 0.5% bupivacaine (1.1 mg kg–1) just before fracture fixation, whereas group P dogs (n = 12) were administered normal saline. Postoperative pain evaluations using the University of Melbourne Pain Scale (UMPS) and algometer were performed upon arrival to the recovery room and 1, 2, 4, 6, 8, 20 and 32 hours later. Algometer measurements were performed on: the incision site, a healthy region near the fracture line and the contralateral healthy limb. When the pain score exceeded 14 points in the UMPS, rescue analgesia was administered. The time-standardised area under the curve (AUCst) was used to compare UMPS scores and mechanical pain thresholds between the two groups. ResultsNone of the group B dogs required rescue analgesia, whereas eight of the 12 group P dogs did (p = 0.001). The pain threshold AUCst at the incision line was higher in group B [16.3 (2.9–41.6) N] than in group P [5.6 (2.5–17.4) N] (p = 0.029). The mean UMPS score AUCst was lower in group B (3.7 ± 1.8) than in group P (9.4 ± 4.6) (p = 0.016). In a small number of animals of both groups that were evaluated radiologically, adequate bone healing was noted. Conclusions and clinical relevanceAn intraoperative bupivacaine haematoma block is a simple, quick and effective method that can be used to aid in postoperative pain control in dogs submitted to long-bone osteosynthesis.

Postoperative pain in dogs undergoing hemilaminectomy: Comparison of the analgesic activity of buprenorphine and tramadol

Abstract The objective of this study was to compare the analgesic activity of buprenorphine and tramadol for the management of postoperative pain after hemilaminectomy because of acute intervertebral disc extrusion in dogs. This is a randomized, blinded, and prospective clinical trial. The study was carried out on 50 dogs undergoing hemilaminectomy. After diagnosis, the dogs were divided randomly into 2 groups: group A (n = 25 dogs) received 3 mg/kg −1 of tramadol intramuscularly and group B (n = 25 dogs) received 0.02 mg/kg −1 of buprenorphine intramuscularly 10-15 minutes before the end of surgery and, then, every 8 and 6 hours, respectively, for 48 hours. Using the short form of the Glasgow Composite Pain Scale at 4 time points (before and 2, 12, and 24 hours after surgery), the dogs were clinically monitored and scored by the same operator who was blinded to the treatment. Data were analyzed using Mann-Whitney U tests. Significance was set at P

Agreement between veterinary students and anesthesiologists regarding postoperative pain assessment in dogs

ObjectiveTo determine the levels of agreement among first- and second-year veterinary students and experienced anesthesiologists in assessing postoperative pain in dogs from video-recordings. Study designCross-sectional study. SubjectsTwenty-seven veterinary students, five anesthesiologists and 13 canine clinical patients. MethodsPrior to their enrolment in a core anesthesia course, veterinary students volunteered to watch 13 90 second videos of dogs. Dogs were hospitalized in an intensive care unit after a variety of surgical procedures. Students were asked to score the level of the dogs’ pain using the Dynamic Interactive Visual Analog Scale and the Short Form of the Glasgow Composite-Measure Pain Scale. The same videotapes were scored by five board-certified anesthesiologists. The differences and agreement between the ratings of anesthesiologists and students, and first- and second-year students were determined with Mann-Whitney U-tests and Fleiss’ or Cohen’s kappa, respectively. ResultsPain scores assigned by students and anesthesiologists differed significantly (p < 0.01). Students assigned higher pain scores to dogs that were given low pain scores by anesthesiologists, and lower pain scores to dogs deemed to be in more pain by anesthesiologists. On average, students assigned higher scores on both scales. Conclusions and clinical relevanceVeterinary students early in their training assigned pain scores to dogs that differed from scores assigned by experienced anesthesiologists.

Attitudes and perceptions of veterinary paraprofessionals in New Zealand to postoperative pain in dogs and cats

AIM: To survey the attitudes and perceptions of veterinary paraprofessionals in New Zealand to postoperative pain in dogs and cats.METHODS: In December 2011, veterinary paraprofessionals (VP) from throughout New Zealand were invited to participate in an online survey. Eleven questions, which were divided into five sections, were used to determine demographic information, the respondents’ assessment of pain after commonly performed surgeries in dogs and cats, their opinions on provision of analgesia, who had responsibility for pain monitoring and the use of any formal pain scoring system in the practice.RESULTS: Data from 165 respondents were able to be used, and 162 (98%) respondents to the survey were female. According to the respondents’ estimates, fracture repair in dogs and repair of diaphragmatic hernias in cats had the highest pain score following surgery. Neutering procedures involving dogs were scored higher than for cats (p<0.01). All respondents agreed that animals benefit from perioperative analgesia. The veterinary nurse was reported to be predominantly responsible for monitoring pain in animals postoperatively by 116/165 (70.3%) respondents. Of 165 respondents, 154 (93%) considered that their knowledge of pain and assessment of pain could be enhanced.CONCLUSIONS: This survey reflects the attitudes and perceptions of a sample of VP in New Zealand to postoperative pain in dogs and cats. The results indicate that all respondents believe that surgery results in sufficient pain to warrant analgesic therapy. Routine neutering surgeries were considered to be more painful in dogs than in cats. The current survey also provides information to educators on potential areas of focus, given that 93% of respondents felt that their knowledge of pain and assessment of pain could be enhanced.

Clinical efficacy of hydrocodone-acetaminophen and tramadol for control of postoperative pain in dogs following tibial plateau leveling osteotomy

To evaluate clinical efficacy of hydrocodone-acetaminophen and tramadol for treatment of postoperative pain in dogs undergoing tibial plateau leveling osteotomy (TPLO). ANIMALS 50 client-owned dogs. Standardized anesthetic and surgical protocols were followed. Each patient was randomly assigned to receive either tramadol hydrochloride (5 to 7 mg/kg, PO, q 8 h; tramadol group) or hydrocodone bitartrate-acetaminophen (0.5 to 0.6 mg of hydrocodone/kg, PO, q 8 h; hydrocodone group) for analgesia after surgery. The modified Glasgow composite measure pain scale was used to assess signs of postoperative pain at predetermined intervals by an investigator who was blinded to treatment group. Scoring commenced with the second dose of the assigned study analgesic. Pain scores and rates of treatment failure (ie, dogs requiring rescue analgesia according to a predetermined protocol) were compared statistically between groups. 12 of 42 (29%; 5/19 in the hydrocodone-acetaminophen group and 7/23 in the tramadol group) dogs required rescue analgesic treatment on the basis of pain scores. Median pain score for the hydrocodone group was significantly lower than that of the tramadol group 2 hours after the second dose of study analgesic. The 2 groups had similar pain scores at all other time points. Overall, differences in pain scores between dogs that received hydrocodone-acetaminophen or tramadol were minor. The percentage of dogs with treatment failure in both groups was considered unacceptable.

Pharmacokinetics of hydrocodone and tramadol administered for control of postoperative pain in dogs following tibial plateau leveling osteotomy

To evaluate the pharmacokinetics of hydrocodone (delivered in combination with acetaminophen) and tramadol in dogs undergoing tibial plateau leveling osteotomy (TPLO). 50 client-owned dogs. Dogs were randomly assigned to receive tramadol hydrochloride (5 to 7 mg/kg, PO, q 8 h; tramadol group) or hydrocodone bitartrate-acetaminophen (0.5 to 0.6 mg of hydrocodone/kg, PO, q 8 h; hydrocodone group) following TPLO with standard anesthetic and surgical protocols. Blood samples were collected for pharmacokinetic analysis of study drugs and their metabolites over an 8-hour period beginning after the second dose of the study medication. The terminal half-life, maximum serum concentration, and time to maximum serum concentration for tramadol following naïve pooled modeling were 1.56 hours, 155.6 ng/mL, and 3.90 hours, respectively. Serum concentrations of the tramadol metabolite O-desmethyltramadol (M1) were low. For hydrocodone, maximum serum concentration determined by naïve pooled modeling was 7.90 ng/mL, and time to maximum serum concentration was 3.47 hours. The terminal half-life for hydrocodone was 15.85 hours, but was likely influenced by delayed drug absorption in some dogs and may not have been a robust estimate. Serum concentrations of hydromorphone were low. The pharmacokinetics of tramadol and metabolites were similar to those in previous studies. Serum tramadol concentrations varied widely, and concentrations of the active M1 metabolite were low. Metabolism of hydrocodone to hydromorphone in dogs was poor. Further study is warranted to assess variables that affect metabolism and efficacy of these drugs in dogs.

Postoperative analgesic effects of either a constant rate infusion of fentanyl, lidocaine, ketamine, dexmedetomidine, or the combination lidocaine-ketamine-dexmedetomidine after ovariohysterectomy in dogs

ObjectiveTo evaluate the postoperative analgesic effects of a constant rate infusion (CRI) of either fentanyl (FENT), lidocaine (LIDO), ketamine (KET), dexmedetomidine (DEX), or the combination lidocaine-ketamine-dexmedetomidine (LKD) in dogs. Study designRandomized, prospective, blinded, clinical study. AnimalsFifty-four dogs. MethodsAnesthesia was induced with propofol and maintained with isoflurane. Treatments were intravenous (IV) administration of a bolus at start of anesthesia, followed by an IV CRI until the end of anesthesia, then a CRI at a decreased dose for a further 4 hours: CONTROL/BUT (butorphanol 0.4 mg kg−1, infusion rate of saline 0.9% 2 mLkg−1 hour−1); FENT (5 μg kg−1, 10 μg kg−1hour−1, then 2.5 μg kg−1 hour−1); KET (1 mgkg−1, 40 μg kg−1 minute−1, then 10 μg kg−1minute−1); LIDO (2 mg kg−1, 100 μg kg−1 minute−1, then 25 μg kg−1 minute−1); DEX (1 μgkg−1, 3 μg kg−1 hour−1, then 1 μg kg−1 hour−1); or a combination of LKD at the aforementioned doses. Postoperative analgesia was evaluated using the Glasgow composite pain scale, University of Melbourne pain scale, and numerical rating scale. Rescue analgesia was morphine and carprofen. Data were analyzed using Friedman or Kruskal–Wallis test with appropriate post-hoc testing (p < 0.05). ResultsAnimals requiring rescue analgesia included CONTROL/BUT (n = 8), KET (n = 3), DEX (n = 2), and LIDO (n = 2); significantly higher in CONTROL/BUT than other groups. No dogs in LKD and FENT groups received rescue analgesia. CONTROL/BUT pain scores were significantly higher at 1 hour than FENT, DEX and LKD, but not than KET or LIDO. Fentanyl and LKD sedation scores were higher than CONTROL/BUT at 1 hour. Conclusions and clinical relevanceLKD and FENT resulted in adequate postoperative analgesia. LIDO, CONTROL/BUT, KET and DEX may not be effective for treatment of postoperative pain in dogs undergoing ovariohysterectomy.

Evaluation of preemptive dexketoprofen trometamol effect on blood chemistry, vital signs and postoperative pain in dogs undergoing ovariohysterectomy.

To investigate the postoperative analgesic effects of preemptive dexketoprofen trometamol in dogs subjected to ovariohysterectomy (OHE). Seventeen adult bitches of various breeds were used in this study. The dogs were randomly allocated into of two groups. Subjects in the dexketoprofen trometamol (DEX) group (n=10), received intravenous (i.v.) dexketoprofen trometamol, 1 mg/kg, 15 minutes before premedication, while those assigned to the control (C) group (n=7) were given no analgesics prior to premedication. Pain level was assessed by two researchers before the administration of anaesthesia (15 minutes before start) and 0, 1, 2, 4 and 6 hours after surgery. A modified University of Melbourne Pain Scale (UMPS) was used to evaluate pain in both groups. Serum cortisol level changed from 0 to 1 h and from 0 to 1 to 4 h were compared between the groups; the increase in the C group was statistically significant. The modified UMPS was applied to both groups at baseline and postoperative 1, 2, 4 and 6 h. According to this test, the values for DEX were significantly lower than controls at 4 and 6 h (p<0.001). Stable vital signs with unchanged biochemical parameters on dexketoprofen administration are a promising finding. The clinical advantage shown by the pain scale difference and the low serum cortisol levels should qualify dexketoprofen for preemptive pain management in dogs (Tab. 5, Fig. 2, Ref. 30).

Anestesia convencional e técnica de tumescência em cadelas submetidas à mastectomia. Avaliação da dor pós-operatória

As neoplasias mamárias são as mais comuns em cadelas e geralmente acometem fêmeas de meia-idade a idosas, não castradas ou que foram submetidas ao procedimento de ovario-histerectomia tardiamente. A principal forma de tratamento é a excisão cirúrgica, sendo a ressecção unilateral das glândulas mamárias o procedimento mais realizado na prática veterinária. O objetivo do presente estudo foi comparar a dor pós-operatória em cadelas submetidas ao procedimento de mastectomia unilateral sob efeito das técnicas anestésicas de tumescência ou convencional. Foram utilizadas 20 cadelas, divididas em dois grupos: um grupo recebeu apenas a anestesia geral inalatória (grupo convencional), e o outro recebeu adicionalmente a anestesia infiltrativa por tumescência (grupo tumescência). Elas foram avaliadas nas primeiras 24 horas do período pós-operatório, e o processo álgico foi avaliado pela escala de dor da Universidade de Melbourne. As médias dos escores obtidos ao longo do tempo foram submetidas ao teste de Tukey a um nível de 5% de significância (p&lt;0,05). Não foram observadas diferenças significativas entre os grupos com relação à dor pós-operatória. A técnica anestésica infiltrativa por tumescência apresentou a vantagem da redução do sangramento transoperatório e mostrou-se exequível em pequenos animais, entretanto seu uso está relacionado à experiência e à preferência do cirurgião e do anestesista.

The safety and effectiveness of a long‐acting transdermal fentanyl solution compared with oxymorphone for the control of postoperative pain in dogs: a randomized, multicentered clinical study

A prospective, double-blinded, positive-controlled, multicenter, noninferiority study was conducted to evaluate the safety and effectiveness of transdermal fentanyl solution (TFS) compared with oxymorphone for the control of postoperative pain in dogs. Five hundred and two (502) client-owned dogs were assigned to a single dose of TFS (2.7 mg/kg) applied 2–4 h prior to surgery or oxymorphone hydrochloride (0.22 mg/kg) administered subcutaneously 2–4 h prior to surgery and q6h through 90 h. Pain was evaluated over 4 days by blinded observers using a modified Glasgow composite pain scale, and the a priori criteria for treatment failure was a pain score ≥8 or adverse event necessitating withdrawal. Four TFS- and eight oxymorphone-treated dogs were withdrawn due to lack of pain control. Eighteen oxymorphone-treated, but no TFS-treated dogs were withdrawn due to severe adverse events. The one-sided upper 95% confidence interval of the difference between TFS and oxymorphone treatment failure rates was −5.3%. Adverse events associated with oxymorphone were greater in number and severity compared with TFS. It was concluded that a single administration of TFS was safe and noninferior to repeated injections of oxymorphone for the control of postoperative pain over 4 days at the dose rates of both formulations used in this study.

Assessment of postoperative pain after unilateral mastectomy using two different surgical techniques in dogs

BackgroundThere are few studies reporting pain and postoperative analgesia associated with mastectomy in dogs. The aim of this study was to evaluate postoperative pain after unilateral mastectomy using two different surgical techniques in the dog.FindingsTwenty female dogs were assigned (n=10/group) to undergo unilateral mastectomy using either the combination of sharp and blunt dissection (SBD) or the modified SBD (mSBD) technique, in which the mammary chain is separated from the abdominal wall entirely by blunt (hand and finger) dissection except for a small area cranial to the first gland, in a prospective, randomized, clinical trial. All dogs were premedicated with intramuscular acepromazine (0.05 mg/kg) and morphine (0.3 mg/kg). Anesthesia was induced with intravenous ketamine (5 mg/kg) and diazepam (0.25 mg/kg), and maintained with isoflurane. Subcutaneous meloxicam (0.2 mg/kg) was administered before surgery. Postoperative pain was evaluated according to the University of Melbourne pain scale (UMPS) by an observer who was blinded to the surgical technique.. Rescue analgesia was provided by the administration of intramuscular morphine (0.5 mg/kg) if pain scores were >14 according to the UMPS. Data were analyzed using t-tests and ANOVA (P>0.05). There were no significant differences between the groups for age, weight, extubation time, and duration of surgery and anesthesia (P>0.05). There were no significant differences for postoperative pain scores between groups. Rescue analgesia was required in one dog in each group.ConclusionsThe two surgical techniques produced similar surgical times, incidence of perioperative complications and postoperative pain. Multimodal analgesia is recommended for treatment of postoperative pain in dogs undergoing unilateral mastectomy.

Effects of tramadol or morphine in dogs undergoing castration on intra-operative electroencephalogram responses and post-operative pain

AIM: To compare the effects of pre-operatively administered tramadol with those of morphine on electroencephalographic responses to surgery and post-operative pain in dogs undergoing castration.METHODS: Dogs undergoing castration were treated with either pre-operative morphine (0.5 mg/kg S/C, n = 8) or tramadol (3 mg/kg S/C, n = 8). All dogs also received 0.05 mg/kg acepromazine and 0.04 mg/kg atropine S/C in addition to the test analgesic. Anaesthesia was induced with thiopentone administered I/V to effect and maintained with halothane in oxygen. Respiratory rate, heart rate, end-tidal halothane tension (EtHal) and end-tidal CO2 tension (EtCO2) were monitored throughout surgery. Electroencephalograms (EEG) were recorded continuously using a three electrode montage. Median frequency (F50), total power (Ptot) and 95% spectral edge frequency (F95) derived from EEG power spectra recorded before skin incision (baseline) were compared with those recorded during ligation of the spermatic cords of both testicles. Post-operatively, pain was assessed after 1, 3, 6 and 9 h using the short form of the Glasgow composite measure pain scale (CMPS-SF).RESULTS: Dogs premedicated with tramadol had higher mean F50 (12.2 (SD 0.2) Hz) and lower Ptot (130.39 (SD 12.1) µv2) compared with those premedicated with morphine (11.5 (SD 0.2) Hz and 161.8 (SD 15.1) µv2, respectively; p<0.05) during ligation of testicle 1. There were no differences in EEG responses between the two treatment groups during ligation of testicle 2 (p>0.05). The F95 of the EEG did not differ between the two groups during the ligation of either testicle (p > 0.05). Post-operatively, no significant differences in the CMPS-SF score were found between animals premedicated with tramadol and morphine at any time during the post-operative period. No dog required rescue analgesia.CONCLUSION AND CLINICAL RELEVANCE: Tramadol and morphine administered pre-operatively provided a similar degree of post-operative analgesia in male dogs at the doses tested.

The Challenges of Assessing Osteoarthritis and Postoperative Pain in Dogs

The challenge of measuring pain in veterinary medicine is compounded by the lack of fully validated, reliable methods to measure and assess pain in nonverbal patients. In human medicine, there are numerous, validated pain assessment tools (PATs) for assessing various, specific types of pain. The advances in human medicine pain management and numerous validated pain scales should serve as incentives and templates to facilitate similar advances in the development of validated PATs for use in dogs (and other species). The limited number of canine PATs constrains our ability to adequately and reliably assess pain. Improving the ability to quantify osteoarthritis and postoperative pain in dogs would enhance the development of analgesics for animals, advance the management of animal pain, facilitate the use of animal pain models in preclinical trials for human analgesics, and provide insight into the quantification of pain responses in humans who lack the ability to adequately communicate. This review describes the need for practical, valid, and reliable PATs for use in veterinary patients and discusses some currently available PATs commonly used to evaluate acute and chronic pain in dogs.

The effectiveness of a long‐acting transdermal fentanyl solution compared to buprenorphine for the control of postoperative pain in dogs in a randomized, multicentered clinical study

A prospective, double-blinded, positive-controlled, multicenter, noninferiority clinical study was conducted to evaluate the safety and effectiveness of a long-acting transdermal fentanyl solution (TFS) for the control of postoperative pain. Four hundred forty-five client-owned dogs of various breeds were randomly assigned to receive a single dose of TFS (2.6 mg/kg [∼50 μL/kg]) (N = 223) applied 2-4 h prior to surgery or buprenorphine (20 μg/kg) (N = 222) administered intramuscularly 2-4 h prior to surgery and every 6 h through 90 h. There were 159 (35.7%) males and 286 (64.3%) females ranging from 0.5 to 16 years of age and 3 to 98.5 kg enrolled. Pain was scored using the modified Glasgow Composite Pain Scale with an a priori dropout criteria of ≥ 8 (20 maximum score). The one-sided upper 95% confidence interval of the mean difference between fentanyl and buprenorphine treatment failures was 5.6%, which was not greater than the a priori selected margin difference of 15%. Adverse events attributed to either treatment were minimal in impact and were approximately equal between groups. Sustained plasma fentanyl concentrations provided by a single pre-emptive dose of TFS are safe and effective and are noninferior to repeated injections of buprenorphine in controlling postoperative pain over 4 days. This long-acting fentanyl formulation provides veterinarians with a novel, registered option for the control of postoperative pain in dogs that improves dosing compliance and potentially mitigates the disadvantages of oral, parenteral, and patch delivered opioids.

The history and pharmacology of fentanyl: relevance to a novel, long‐acting transdermal fentanyl solution newly approved for use in dogs

Fentanyl is a potent mu opioid receptor agonist that was discovered to identify an improved human health analgesic over morphine, an opioid frequently associated with histamine-release, bradycardia, hyper- or hypotension, and prolonged postoperative respiratory depression. Historically, the pharmacological features of fentanyl have been described primarily through the study of the human approved fentanyl citrate formulation. In conscious dogs, fentanyl has a wide margin of safety, possesses minimum effects on the cardiovascular and respiratory systems, and is readily reversible. Other pharmacological features include sedation, mild reductions in body temperature, and dose-dependent reduction in food intake. The short duration of effect of available fentanyl citrate solutions has limited its clinical use to perioperative injections or constant rate infusions (CRIs). To extend the analgesic effect, additional fentanyl delivery technologies have been developed for human health including the fentanyl patch that has been used in an extra-label manner in dogs. Beyond the slow onset and variability in fentanyl delivery, several additional disadvantages have precluded common use of patches in dogs. The recent approval of long-acting transdermal fentanyl solution for dogs provides a new approach for sustained delivery of fentanyl for the control of postoperative pain in dogs. It has a rapid onset of action, prolonged duration, and mitigates the disadvantages of oral, parenteral, and patch-delivered opioids. The availability of a safe and effective approved opioid in dogs may allow further optimization of postoperative analgesia in this species. The objective of this review is to summarize the history and pharmacology of fentanyl and to integrate information about the newly approved long-acting transdermal fentanyl solution.

Population pharmacokinetics of transdermal fentanyl solution following a single dose administered prior to soft tissue and orthopedic surgery in dogs

A novel, long-acting transdermal fentanyl solution (TFS) that delivers sustained plasma fentanyl concentrations following a single application for the control of postoperative pain has recently been approved for use in dogs. The pharmacokinetics (PKs) of this formulation have been evaluated in healthy laboratory dogs, but they have not been reported in a clinical population of dogs for which it is indicated. Plasma fentanyl concentrations were determined from 215 dogs following a single, small-volume (∼50 μL/kg) dose of TFS administered 2-4 h prior to orthopedic or soft tissue surgery. A population PK model was fit, and a 1-compartment open PK model with first-order absorption and an absorption lag-time best described the data. No tested clinical covariates had a significant effect on the PKs. The final model adequately described the population PKs and gave results consistent with laboratory PK studies in healthy dogs. The PKs were primarily characterized by a rapid initial increase in plasma fentanyl concentrations and a long terminal half-life of 74.0 (95% C.I. [54.7-113]) h governed by flip-flop kinetics for the typical subject. The plasma fentanyl concentrations were sustained over days in the range considered to be analgesic for postoperative pain in dogs.

Postoperative pain and perioperative analgesic administration in dogs: practices, attitudes and beliefs of Queensland veterinarians

The aim of this study was to describe the practices, attitudes and beliefs of Queensland veterinarians in relation to postoperative pain and perioperative analgesia in dogs. One veterinarian from each of the 50 randomly selected Queensland veterinary practices was enrolled after selection by convenience sampling. The study response rate was 94.3%. Demeanour, vocalisation and heart rate were the most common postoperative pain assessment tools used, even though the most sensitive tools were considered to be demeanour, heart rate and respiratory rate. Only 20% of respondents used formalised pain scoring systems. Preoperative analgesic administration was always used by 72% of respondents. There was marked variability in the frequency with which analgesia was administered perioperatively for ovariohysterectomy. Only 24% of veterinarians discharged animals with ongoing analgesia even though 38% agreed that pain is still present 7 days postoperatively. Multimodal analgesia was used by 82% of respondents. Epidural and local anaesthetic analgesic techniques were not being utilised by any respondents. Conclusions These results indicate that management of postoperative pain in dogs in Queensland is frequently suboptimal and, at times, is not consistent with the veterinarian's attitudes and beliefs. Continuing education into analgesic use and pain evaluation may be effective in addressing this.