Characteristics of pain and response to analgesic treatment in dogs and cats examined at a veterinary teaching hospital emergency service

OBJECTIVE: To estimate the prevalence and characteristics of pain in dogs and cats examined by an emergency service at a veterinary teaching hospital and evaluate the response of dogs and cats with signs of pain to analgesic treatment. DESIGN: Cross-sectional study. ANIMALS: 317 dogs and 112 cats. PROCEDURE: A questionnaire was used to categorize the characteristics of pain. The location, cause, and signs of pain were determined by obtaining a thorough history and conducting a physical examination. Pain was categorized by type (superficial somatic, deep somatic, or visceral), mechanism (inflammatory, neuropathic, or both), severity (mild, moderate, or severe), and duration. Evidence for primary or secondary hypersensitivity and hyposensitivity to manipulation was determined. The response to single or multiple analgesic drug administration was assessed. RESULTS: 179 (56%) dogs and 60 (54%) cats had signs of pain. In most of these dogs and cats, pain was classified as acute (< 24 hours' duration) and of moderate severity and was associated with primary hypersensitivity. Most dogs had deep somatic pain; most cats had visceral pain. Inflammation was the most common mechanism. One hundred nineteen (66%) dogs and 41 (68%) cats were treated with analgesic drugs. Analgesic treatment was considered effective in 73 (61%) dogs and 31 (76%) cats. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that moderate to severe acute somatic pain caused by inflammation is common in dogs and cats examined by an emergency service and that a combination of multiple analgesic drugs is more effective than any single analgesic drug in the treatment of pain in these dogs and cats.     

A comparison of epidural buprenorphine with epidural morphine for postoperative analgesia following stifle surgery in dogs

Objective To compare the efficacy of epidural buprenorphine with epidural morphine for post‐operative pain relief in dogs undergoing cranial cruciate ligament rupture repair. Study design A randomized, double blind clinical trial. Animals Twenty client‐owned dogs with cranial cruciate ligament rupture. Methods Dogs were randomly assigned to receive either epidural buprenorphine (4 µg kg^?1) or epidural morphine (0.1 mg kg^?1) in a total volume of 0.2 mL kg^?1. Epidural injections were performed immediately after induction of anesthesia. End‐tidal halothane and CO₂ were recorded every 15 minutes from the time of epidural administration of drug to extubation. A numerical rating pain score system was used by a blinded observer to evaluate analgesia beginning at extubation and continuing at specific intervals for 24 hours after surgery. Heart rate, respiratory rate, and blood pressure were recorded noninvasively at the same times. If pain score indicated moderate discomfort, rescue morphine at 1.0 mg kg^?1 was administered intramuscularly. Results There were no significant differences between groups with respect to pain score, heart rate, respiratory rate, indirect blood pressure, end‐tidal halothane or end‐tidal CO₂ at any time point. Fifty percent of dogs in the buprenorphine group and 50% of dogs in the morphine group required rescue analgesic medication. Time of systemic rescue morphine administration did not differ significantly between the two groups. There were no clinically observable side‐effects from epidural administration of either drug in any of the dogs of this study. Conclusions Epidural buprenorphine is as effective as epidural morphine for the relief of postoperative hindlimb orthopedic pain in dogs. Clinical relevance Buprenorphine appears to be an effective opioid for epidural use in healthy dogs. Buprenorphine may offer certain advantages over morphine for epidural use, such as lower abuse potential and, in some clinics, reduced cost and less wastage of drug.     

Anticonvulsant activity and tolerance of ELB138 in dogs with epilepsy: a clinical pilot study

A new antiepileptic and anxiolytic drug, ELB138, was evaluated in a clinical pilot study in dogs with newly diagnosed or chronic idiopathic epilepsy. The purpose was to verify clinically the anticonvulsant effectiveness of this substance, which had already been demonstrated experimentally. Data from 29 dogs treated with ELB138 were compared with results obtained retrospectively from 82 dogs treated with conventional antiepileptic medication. The reduction in seizure frequency using ELB138 in dogs with newly diagnosed idiopathic epilepsy was comparable to the reduction in dogs treated either with phenobarbital or primidone. In dogs with chronic epilepsy and add-on therapy with either ELB138 or potassium bromide, such supplementation reduced the seizure frequency and the duration and severity of seizures. The most obvious difference between ELB138 treatment and conventional medications became clear in the evaluation of side effects, which in those dogs treated with ELB138 were rare, and consisted mostly of transient polyphagia. This pilot study confirmed that ELB138 has a potent anticonvulsant effect in dogs with idiopathic epilepsy. These results will form the basis for a multicentre, blinded study.     

Analgesic effect of meloxicam in canine acute dermatitis--a pilot study

A double-blind trial was performed on 12 client-owned dogs suffering from acute and painful dermatitis. Clinically these cases represented pyotraumatic dermatitis and pyotraumatic folliculitis. Six dogs were injected with meloxicam and 6 were given placebo. Signs of pain were recorded on a visual analogue scale before administering the drug. This was repeated over the following 2-3 days. All dogs were treated with cephalexin orally. Six dogs given meloxicam and cephalexin showed an average decrease of pain on day 2 of 28.3%, whereas the 6 dogs given placebo and cephalexin showed an average decrease of pain on day 2 of 8.3%. When compared in the Wilcoxon two-sample test, using change in percent and absolute change, the 2 groups yielded p = 0.026 and p = 0.064 respectively. These findings indicate that meloxicam has an analgesic effect on acute dermatitis in dogs.     

The use of analgesic drugs by South African veterinarians

According to a survey, non-steroidal anti-inflammatory agents were the most popular analgesic used in South Africa for management of peri-operative pain, acute post-operative pain and chronic pain. The most popular non-steroidal anti-inflammatory agents are flunixin meglumine and phenylbutazone. The most popular opioid type drug is buprenorphine, followed by morphine. In the peri-operative setting, analgesic agents were not actively administered to 86.3% of cats and 80.7% of dogs. Analgesic premedications were frequently administered, e.g. xylazine or ketamine, but no specific drug was administered for post-operative pain. Veterinarians need to critically review their anaesthetic and analgesic practices in order to achieve balanced anaesthesia.     

Prevalence and characteristics of pain in dogs and cats examined as outpatients at a veterinary teaching hospital

OBJECTIVE: To determine prevalence of pain among dogs and cats examined as outpatients at a veterinary teaching hospital and characteristics of pain in dogs and cats with evidence of pain. DESIGN: Cross-sectional study. ANIMALS: 1,153 dogs and 652 cats examined as outpatients at The Ohio State University during 2002. PROCEDURE: A questionnaire was administered to owners of all dogs and cats. For dogs and cats with evidence of pain, the cause, signs, anatomic location, type (superficial somatic, deep somatic, or visceral), duration, and severity of the pain and the principle mechanism (inflammatory, neuropathic, both, or unknown) responsible for the pain were determined on the basis of questionnaire responses and results of physical examination. The presence of primary hyperalgesia, secondary hyperalgesia, allodynia, and hyposensitivity was recorded. RESULTS: 231 (20%) dogs and 92 (14%) cats had evidence of pain. Dogs with evidence of pain were significantly older and heavier than dogs without. Cats with evidence of pain were significantly older than cats without. In most dogs and cats with evidence of pain, the pain was determined to be of short duration (< 7 days), of mild or moderate severity, somatic, associated with primary hyperalgesia, and inflammatory. Analgesic drugs were frequently administered to dogs with chronic pain, but were not always considered effective. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that mild or moderate pain associated with inflammation may be seen in dogs and cats examined as outpatients. Older, heavier dogs and older cats were more likely to have evidence of pain.     

Diagnosis and treatment of arthrosis of cervical articular facet joints in Scottish Deerhounds: 9 cases (1998-2002)

OBJECTIVE: To determine diagnostic features and efficacy of treatment of arthrosis of the cervical articular facet joints between C2 and C3 in Scottish Deerhounds. DESIGN: Retrospective study. ANIMALS: 9 client-owned dogs. PROCEDURE: Medical records of affected dogs were reviewed. Diagnosis was confirmed by results of clinical examination (signs of severe pain from unilateral or bilateral flexion of the cervical vertebral column), radiography, myelography, and computed tomography. Treatment consisted of fluoroscopy-guided intra-articular injection of corticosteroids and lidocaine. RESULTS: Unilateral or bilateral arthrosis of the cervical facet joints between C2 and C3 was detected in all dogs. In 7 dogs, signs of pain were elicited by flexion of the side of the neck in which affected joints were detected radiographically. Two dogs had signs of pain during right lateral flexion, although bilateral lesions were detected. Five dogs had unilateral lesions, and 4 dogs had bilateral lesions; sclerosis and hypertrophy of the articular process were common. Two dogs had bridging of the articular space. Use of computed tomography confirmed the diagnosis. Myelography did not reveal abnormalities of the spinal cord or canal. After treatment, 8 dogs had rapid marked improvement of clinical signs, and 7 dogs remained free of clinical signs for > 4 months. CONCLUSIONS AND CLINICAL RELEVANCE: Arthrosis of the cervical facet joints in Scottish Deerhounds is a severely painful condition for which conventional radiography is a useful screening test. Intra-articular administration of corticosteroids and anesthetic is efficacious, long-lasting, and minimally invasive.     

Effect of carprofen, etodolac, meloxicam, or butorphanol in dogs with induced acute synovitis

OBJECTIVE: To compare the analgesic and anti-inflammatory effect of single doses of carprofen, etodolac, meloxicam, and butorphanol in dogs with induced acute synovitis (acute pain model) via kinetic gait analysis and orthopedic evaluation and examine measurement of serum C-reactive protein (CRP) concentration as an indicator of treatment efficacy. ANIMALS: 12 Beagles and 6 additional Beagles that were used only in serum CRP analyses. PROCEDURE: Acute synovitis was induced in right stifle joints of dogs via intra-articular injection of monosodium urate solution. Treatments included butorphanol (0.2 mg/kg, i.v.), carprofen (4 mg/kg, PO), etodolac (17 mg/kg, PO), or meloxicam (0.2 mg/kg, PO); control dogs received no treatment. The procedure was repeated (3-week intervals) until all dogs received all treatments including control treatment. Lameness was assessed on a biomechanical force platform and via orthopedic evaluations of the stifle joints; blood was collected to monitor serum CRP concentration. RESULTS: Compared with control dogs, treated dogs had significantly different vertical ground reaction forces and weight-bearing scores. Greatest improvement in lameness was observed in carprofen-treated dogs. Etodolac had the fastest onset of action. Compared with butorphanol treatment, only carprofen and etodolac were associated with significantly lower pain scores. An increase in serum CRP concentration was detected after intra-articular injection in all dogs; this change was similar among groups. CONCLUSIONS AND CLINICAL RELEVANCE: Carprofen, etodolac, and meloxicam had greater efficacy than butorphanol in relief of acute pain. Carprofen was most effective overall. In this acute pain model, serum CRP analysis was not useful to assess drug efficacy.     

Postoperative use of analgesics in dogs and cats by Canadian veterinarians.

Four hundred and seventeen Canadian veterinarians were surveyed to determine their postoperative use of analgesics in dogs and cats following 6 surgical procedures, and to determine their opinions toward pain perception and perceived complications associated with the postoperative use of potent opioid analgesics. Three hundred and seventeen (76%) returned the questionnaire. The percentage of animals receiving analgesics postoperatively ranged from 84% of dogs and 70% of cats following orthopedic surgery to 10% of dogs and 9% of cats following castration. In general, with the exception of orthopedic surgery, roughly equal percentages of dogs and cats received postoperative analgesics. Opioids were used almost exclusively to provide postoperative analgesia, with butorphanol the most commonly administered drug to both dogs and cats. Analgesics were usually administered either once or twice postoperatively. With regard to the administration of potent opioid agonists, the 3 major concerns included respiratory depression, bradycardia, and sedation in dogs, and excitement, respiratory depression, and bradycardia in cats. Seventy-seven percent of veterinarians considered their knowledge of issues related to the recognition and control of postoperative pain to be inadequate. Experience in practice is currently the major source of knowledge, with undergraduate veterinary school and research articles in journals ranked as the least important sources. Lectures or seminars delivered at the regional level were the preferred format for continuing education.     

Pathophysiology and treatment of neuropathic pain associated with syringomyelia

The pain behaviour expressed by dogs with syringomyelia suggests that they experience neuropathic pain, probably due to disordered neural processing in the damaged dorsal horn. As such it is likely that conventional analgesic medication will be ineffective. In this review, physiological and pathological pain processing through the dorsal horn is summarised and mechanisms by which syringomyelia could result in a persistent pain state are discussed. Finally, current knowledge regarding treatment of Chiari malformation and syringomyelia is reviewed and possible drugs which may give improved pain relief in affected dogs are discussed.     

Syringomyelia in cavalier King Charles spaniels: the relationship between syrinx dimensions and pain

OBJECTIVES: This study was designed to test the hypothesis that pain associated with syringomyelia in dogs is dependent upon size and involvement of the dorsal part of the spinal cord. METHODS: Masked observers determined syrinx dimensions and precise location within the spinal cord on magnetic resonance images of 55 cavalier King Charles spaniels with syringomyelia. After removal of masking, syrinx size and location were compared between the cohorts of dogs that exhibited pain with those that did not. RESULTS: Maximum syrinx width was the strongest predictor of pain, scratching behaviour and scoliosis in dogs with syringomyelia. Both pain and syrinx size were positively correlated with syrinxes located in the dorsal half of the spinal cord. CLINICAL SIGNIFICANCE: Large syrinxes associated with damage to the dorsal part of the spinal cord are associated with persistent pain suggesting that the pain behaviour expressed by this group of patients is likely to be "neuropathic pain," resulting from disordered neural processing in the damaged dorsal horn. As such it is likely that conventional analgesic medication may be ineffective.     

Effects of combinations of medetomidine/pethidine when used for sedation and pre-anaesthetic medication in dogs

Medetomidine, either 5, 10 or 20 (μg/kg, was administered together with pethidine, 2 mg/kg, by either the intramuscular or subcutaneous route to 88 dogs from a clinical population. Administration of all the drug combinations consistently produced profound sedation in the dogs, accompanied by dramatic reductions in heart rate. The degree of sedation was similar to that seen after 40 μg/kg medetomidine is administered on its own to dogs. Intramuscular administration produced more reliable sedation, but was associated with more pain than subcutaneous administration. In a number of dogs, sedation permitted the completion of various diagnostic or therapeutic procedures. Several dogs were anaesthetised with thiopentone and the induction doses required were characteristically low (mean doses between 2 to 3·3 mg/kg depending on the dose of medetomidine and the route of administration). Administration of atipamezole at the termination of sedation or anaesthesia, produced a rapid and full recovery (mean time to standing between seven and 11 minutes).     

Validity of a health-related quality-of-life scale for dogs with signs of pain secondary to cancer

OBJECTIVE: To develop and validate a health-related quality-of-life scale for dogs with pain secondary to cancer. DESIGN: Questionnaire development. ANIMALS: 40 healthy dogs with no history or signs of pain, 20 dogs with dermatologic disease but no signs of pain other than mild pruritus, and 20 dogs with cancer. PROCEDURE: Owners of all dogs completed a questionnaire containing 12 questions with 4 options for each question, and a quality-of-life score ranging from 0 to 36 was calculated. Scores for dogs with cancer were compared with scores for healthy dogs and dogs with dermatologic disease. RESULTS: All owners indicated that the questionnaire was easy to complete. Scores for healthy dogs were significantly different from scores for dogs with cancer and scores for dogs with dermatologic disease. Scores for dogs with dermatologic disease were significantly different from scores for dogs with cancer. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that a simple questionnaire may be useful in assessing health-related quality of life in dogs with pain secondary to cancer, in that dogs with cancer had significantly lower scores than did healthy dogs and dogs with dermatologic disease.     

Pharmacokinetics of clindamycin HCl administered intravenously, intramuscularly and subcutaneously to dogs

A buffered aqueous solution of clindamycin Hcl (200 mg/mL) was injected intravenously (i.v.) intramuscularly (i.m.) and subcutaneously (s.c.) in a non-randomized, partial cross-over trial involving six male and six female dogs. Blood samples were collected at conventional, predetermined time periods and serum drug concentrations were determined by microbiological assay. Dogs were observed clinically for signs of pain, and activity of serum creatine phosphokinase (CPK) was monitored after i.m. dosing. The i.v. data from five of the dogs best fitted a two-compartment open-system pharmacokinetic model whereas a non-compartment model was most suitable for analysis of the data from the remaining seven dogs. The mean i.v. elimination half-life (t1/2 beta) and the mean residence time (MRT) were 124 and 143 min, respectively. The mean volume of distribution at steady state (Vss) was 0.86 L/kg. Little pain was recorded upon i.m. injection; mean peak serum drug concentration (Cmax) was 4.4 micrograms/mL, the elimination half-life (t1/2el) was 247 min and the calculated bioavailability (F) was 115% of the i.v. dose. Serum CPK activity was elevated to 25-fold the pretreatment level in samples collected 4, 8 and 12 h after i.m. injection. Pain was not recorded after s.c. drug administration; the mean Cmax of 20.8 micrograms/mL was significantly greater than the corresponding value for the i.m. route, and F was 310%. The s.c. route appears to be superior to the i.m. route in terms of local tolerance and serum drug level; a 10 mg/kg SID treatment regimen is suggested for treatment of canine infections due to clindamycin sensitive bacteria.     

Duration, complications, stress, and pain of open ovariohysterectomy versus a simple method of laparoscopic-assisted ovariohysterectomy in dogs

OBJECTIVE: To describe a simple method of laparoscopic-assisted ovariohysterectomy (LAOHE) and compare duration of surgery, complications, measures of surgical stress, and postoperative pain with open ovariohysterectomy (OHE) in dogs. DESIGN: Randomized, prospective clinical trial. ANIMALS: 20 healthy sexually intact female dogs weighing >10 kg (22 lb). PROCEDURES: Dogs were randomly allocated to receive conventional OHE or LAOHE. Intraoperative complications, anesthetic complications, total anesthesia time, and total surgery time were recorded. Serum cortisol and glucose concentrations, temperature, heart rate, and respiratory rate were measured preoperatively and 1, 2, 4, 6, 12, and 24 hours postoperatively. Pain scores were assigned by a nonblinded observer at 1, 2, 4, 6, 12, and 24 hours postoperatively. Duration of surgery, pain scores, objective measures of surgical stress, anesthetic complications, and surgical complications were compared between OHE and LAOHE. RESULTS: Age, weight, PCV, and duration of surgery did not differ between treatment groups. Nine of 10 dogs in the OHE group required additional pain medication on the basis of pain scores, whereas none of the dogs in the LAOHE group did. Blood glucose concentrations were significantly increased from preoperative concentrations in the OHE group at 1, 2, 4, and 6 hours postoperatively and at 1 hour postoperatively in the LAOHE group. Cortisol concentrations were significantly increased at 1 and 2 hours postoperatively in the OHE group. CONCLUSIONS AND CLINICAL RELEVANCE: LAOHE caused less pain and surgical stress than OHE and may be more appropriate for an outpatient setting.     

Plasmapheresis in five dogs with systemic immune-mediated disease

Five dogs with signs referable to systemic immune-mediated disease, four with systemic lupus erythematosus, and one with probable lupus myopathy were treated with plasmapheresis in combination with low-dose immunosuppressive drug therapy. Previous treatment with conventional dosages of prednisone was not satisfactory and was associated with adverse side effects. Two dogs had short-term responses to combined therapy, and 3 dogs had sustained responses. Clinical remission was associated with normalization of serum complement levels and decreases in antinuclear antibody titers. Toxicosis potentially related to plasma component depletion was observed in 2 dogs. Acute clinical illness and disease states refractory to conventional immunosuppressive therapy should be considered indications for plasmapheresis.     

Effects of preoperative administration of meloxicam on whole blood platelet aggregation, buccal mucosal bleeding time, and haematological indices in dogs undergoing elective ovariohysterectomy

The purpose of the study was to evaluate the effect of preoperative administration of meloxicam, a non-steroidal anti-inflammatory drug used for pain control, on primary haemostasis in dogs. Twenty healthy female dogs undergoing elective ovariohysterectomy were enrolled in the study. Sixty minutes before pre-anaesthesia, a single dose of meloxicam (0.2 mg/kg) was randomly administered intravenously (IV) to 10 dogs (treatment group) while control dogs received an equivalent volume of saline solution IV. Platelet aggregation, buccal mucosa bleeding time, platelet count and haematological indices were measured at 0, 1, 6 and 24 h after administration of meloxicam. Since significant differences between groups were not observed for any of the measured parameters, preoperative administration of meloxicam may be used for pain control before elective ovariohysterectomy in healthy dogs, without compromising primary haemostasis.     

Incisional block with bupivacaine for analgesia after celiotomy in dogs

A blind, placebo-controlled clinical trial was performed to evaluate the postoperative analgesic effect of preoperative infiltration of the incision site with bupivacaine in dogs undergoing celiotomy. Sixty dogs were randomly allocated into four groups: preoperative bupivacaine, postoperative bupivacaine, preoperative saline, and postoperative saline. All dogs were premedicated with acepromazine and meperidine; then they were anesthetized with thiopentone and isoflurane. Each group received either bupivacaine or normal saline before midline incision or just before skin closure. After surgery, pain scores were assigned using a numerical rating scale. Preoperative bupivacaine was associated with significantly lower pain scores and a significantly lower need for opioid administration. The authors conclude that a preoperative incisional block with bupivacaine seems to be a useful adjunct for controlling pain after celiotomy in dogs.     

Development of a scale to evaluate postoperative pain in dogs

OBJECTIVE: To design and evaluate a scale for measurement of postoperative pain in dogs. DESIGN: Randomized, blinded, prospective study, with positive- and negative-control groups. ANIMALS: 36 dogs undergoing general anesthesia for ovariohysterectomy and 12 dogs undergoing general anesthesia without surgery. PROCEDURE: A pain assessment scale was developed for dogs, which incorporated physiologic data (heart and respiratory rates) and behavioral responses (response to palpation, activity, mental status, posture, and vocalization). This pain scale was then applied to a study in which dogs were allocated to 2 groups, depending on the type of medication administered (acepromazine maleate only or acepromazine and butorphanol) before induction of general anesthesia. The 36 dogs that had ovariohysterectomy were allocated to 3 groups, members of which received butorphanol, carprofen, or no analgesic after surgery. Dogs were scored for signs of pain and videotaped at 0, 1, 2, 4, 6, 8, 12, and 18 hours after surgery by an assessor who was blinded to the groups. Results were analyzed for significant differences in pain scores for single categories and total pain scores among groups. Video segments were scrambled and then scored by a second external assessor to test the repeatability of the results, using the pain assessment scale. RESULTS: Mean total pain scores were significantly different between the group of dogs that underwent general anesthesia only and each group of dogs that underwent general anesthesia and surgery. Pain scores for the analgesic-treatment groups reflected the known onset and duration of action of the analgesic used. Agreement between the internal and external assessors was excellent and indicated high precision between the 2 assessors for the population of dogs as a whole. CLINICAL IMPLICATIONS: Behavioral and physiologic measurements can be used reliably to evaluate degree of pain in dogs during the postoperative period and their response to analgesics.