Managing pain in feline patients

Temporomandibular Joint Gape Angles in Normal and Painful Domestic Felines

The purpose of this study was to determine and compare the gape angles (temporomandibular joint range of motion with mouth opening) of conscious and anesthetized domestic felines and to compare gape angles with and without evidence of oral pain. This prospective study evaluated the gape angle of 58 domestic felines. The cats were grouped into painful (n = 33) and nonpainful cohorts (n = 25) and gape angles were compared during conscious and anesthetized conditions. Gape angles were determined based on measurements of the maximal interincisal distance and lengths of the mandible and maxilla followed by calculation of the law of cosines. The mean feline gape angle (standard deviation) was determined to be 45.3° (8.6°) and 50.8° (6.2°) for conscious and anesthetized felines respectively. There was no significant difference between painful and non-painful feline gape angles during conscious (P = .613) or anesthetized (P = .605) evaluations. There was a significant difference between anesthetized and conscious gape angles (P < .001) for both painful and non-painful cohorts. This study determined the standardized, normal feline temporomandibular joint (TMJ) gape angle in both conscious and anesthetized states. This study suggests that the feline gape angle is not a useful indicator of oral pain. By determining the feline gape angle, which was previously unknown, further evaluation of its utility as a non-invasive clinical parameter for evaluation of restrictive TMJ motions as well as its use for serial evaluations may be pursued.

"What Would You Do?": How Cat Owners Make End-of-Life Decisions and Implications for Veterinary-Client Interactions

Cats are the most common companion animals in New Zealand. Advances in veterinary care means that cats are living longer and there are many older cats. End-of-life decisions about cats are complicated by owner-cat relationships and other psychosocial factors. Our study explored the ways in which end-of-life decisions were being made by owners of older and chronically ill cats in New Zealand and the role of their veterinarian in the process. Qualitative data were gathered via retrospective semi-structured interviews with 14 cat owners using open-ended questions. Transcripts of these interviews were explored for themes using template analysis and nine themes were identified. Four were animal-centered themes: cat behavior change, pain was a bad sign, signs of ageing are not good, and the benefits of having other people see what owners often could not. Five were human-centered themes: veterinarians understanding owners' relationships with their cat, normalizing death, the need for a good veterinarian to manage end of life, veterinary validation that owners were doing the right thing, and a strong desire to predict the time course and outcome for their cat. End-of-life decision making is complex, and the veterinarian's role is often poorly defined. Our owners appreciated the expertise and validation that their veterinarian provided but continuity of care was important. Future research aimed at exploring the veterinarian's perspective during end-of-life decision making for cats would be a valuable addition to the topic.

Evaluation of meloxicam for the treatment of obstructive feline idiopathic cystitis

Objectives The aim of the study was to investigate the effect of the non-steroidal anti-inflammatory drug meloxicam on the clinical course of obstructive idiopathic cystitis in cats in a placebo-controlled clinical study. Methods Thirty-seven cats with obstructive idiopathic cystitis were enrolled. Cats received supportive treatment and an indwelling transurethral catheter for 48 h. On days 0 and 1, all cats received buprenorphine 0.01 mg/kg subcutaneously every 8 h. On day 1, cats were randomly assigned to the meloxicam (n = 18) or placebo group (n = 19) and received meloxicam (0.1 mg/kg on day 1, 0.05 mg/kg on days 2-5) or placebo orally for five consecutive days. Cats were monitored by repeated physical examinations and urinalysis, and with a 5 day questionnaire filled in by the owners after discharge and a telephone interview 3 months after presentation. Parameters for evaluation of treatment success were the occurrence of recurrent urethral obstruction, results of physical examinations and questionnaires. Results Recurrent urethral obstruction occurred in 4/18 cats (22%) in the meloxicam group and 5/19 cats (26%) in the placebo group ( P = 1.000). General demeanour and pain on abdominal palpation during hospitalisation improved significantly in both groups ( P <0.001). After discharge, with regard to general demeanour, food intake and voiding behaviour, there were no significant differences within or between groups at different time points. Conclusions and relevance Orally administered meloxicam for 5 days did not influence the incidence of recurrent urethral obstruction and the recovery from clinical signs in cats with obstructive feline idiopathic cystitis. The persistence of clinical signs in most of the cats 1 week after initial presentation indicates that symptomatic treatment for a longer period of time is warranted.

Antinociceptive effects of intravenous administration of hydromorphone hydrochloride alone or followed by buprenorphine hydrochloride or butorphanol tartrate to healthy conscious cats

OBJECTIVE

To evaluate antinociceptive effects of IV administration of hydromorphone alone or followed by buprenorphine or butorphanol to cats.

ANIMALS

6 healthy adult cats.

PROCEDURES

In a randomized, blinded crossover design, cats received each of 4 treatments in which 2 IV injections were given 30 minutes apart: 2 of saline (0.9% NaCl) solution (Sal-Sal) or 1 each of hydromorphone HCl and saline solution (H-Sal), hydromorphone and buprenorphine HCl (H-Bupre), or hydromorphone and butorphanol tartrate (H-Butor). Skin temperature and thermal threshold were recorded before (baseline) and for 12 hours after the first injection. Percentage of maximum possible effect (%MPE) and thermal excursion (TE) were compared among treatments and measurement points.

RESULTS

Compared with baseline values, skin temperature was higher from 0.75 to 2 hours after the first injection for H-Sal; at 0.5, 1, 3, and 4 hours for H-Bupre; from 0.5 to 3 hours for H-Butor; and from 0.5 to 1 hours for Sal-Sal. Thermal excursion was higher than at baseline from 0.25 to 2 hours for H-Sal and H-Bupre and 0.25 to 0.75 hours for H-Butor; %MPE increased from 0.25 to 2 hours for H-Sal, 0.25 to 3 hours for H-Bupre, and 0.25 to 0.75 hours for H-Butor. Results were similar for comparisons with Sal-Sal, except TE was greater for H-Sal versus Sal-Sal and TE and %MPE were greater for H-Bupre versus Sal-Sal from 0.25 to 1 hours after the first injection.

CONCLUSIONS AND CLINICAL RELEVANCE

Butorphanol administration decreased the duration of antinociception achieved with hydromorphone administration in cats. This opioid interaction and its impact on pain management require additional investigation.

Evaluation of injectable robenacoxib for the treatment of post-operative pain in cats: results of a randomized, masked, placebo-controlled clinical trial

Background

Few pharmaceuticals are registered in cats for the management of post-operative pain and inflammation. The objective of this study was to assess the field efficacy and safety of an injectable formulation of the nonsteroidal anti-inflammatory drug robenacoxib in cats undergoing surgery. The study was a multi-center, prospective, randomized, masked, parallel-group, placebo-controlled clinical trial. A total of 349 cats were enrolled and underwent surgery comprising forelimb onychectomy, as an example of orthopedic surgery, plus either ovariohysterectomy or castration. All cats received butorphanol prior to anesthesia and forelimb four-point regional nerve blocks with bupivacaine after induction of general anesthesia. Cats were randomized to receive daily subcutaneous (s.c.) injection of robenacoxib, at a target dosage of 2.0 mg/kg (n = 174), or placebo (n = 175) once prior to surgery and for an additional two days post-operatively.

Results

Significantly (P = 0.037) fewer cats administered robenacoxib received additional analgesia rescue therapy (34 of 173, 19.7 %) compared to cats given placebo (73 of 175, 41.7 %). The percentage of treatment success was therefore 80.3 % with robenacoxib and 58.3 % with placebo. Behavior, posture, pain on palpation of the paw and soft tissue surgery sites, and overall pain were significantly (P < 0.05) improved versus placebo at various time points within the first 8 h in cats receiving robenacoxib. The most frequently reported adverse events were incision site infection/dehiscence, bleeding, vomiting, decreased appetite and lethargy. Frequencies of reported adverse clinical signs, hematology, serum chemistry and urinalysis variables, and body weight changes were similar between groups. There were no significant changes from baseline with robenacoxib in hepatic, hematological or renal clinical pathology variables.

Conclusions

Robenacoxib by s.c. injection was effective and well tolerated in the control of post-operative pain associated with orthopedic, ovariohysterectomy and castration surgery in cats.

Evaluation of oral robenacoxib for the treatment of postoperative pain and inflammation in cats: results of a randomized clinical trial

The efficacy and safety of robenacoxib were assessed for the control of postoperative pain and inflammation in cats. The study was a multicenter, prospective, randomized, blinded, and parallel group clinical trial. A total of 249 client-owned cats scheduled for forelimb onychectomy plus either ovariohysterectomy or castration surgeries were included. All cats received butorphanol prior to anesthesia and forelimb four-point regional nerve blocks with bupivacaine after induction of general anesthesia. Cats were randomized to receive daily oral tablet robenacoxib, at a mean (range) dosage of 1.84 (1.03–2.40) mg/kg (n = 167), or placebo (n = 82), once prior to surgery and for two days postoperatively. Significantly (P < 0.05) fewer robenacoxib cats received additional analgesia rescue therapy (16.5%) than placebo cats (46.3%). Pain elicited on palpation of the soft tissue incision site, behavior following social interaction, and posture assessed during the first 8 hours after extubation were significantly (P < 0.05) improved in cats receiving robenacoxib. Frequency of reported adverse clinical signs, hematology, serum chemistry and urinalysis variables, and body weight changes weresimilar between groups. In conclusion, robenacoxib was effective and well tolerated in the control of postoperative pain and inflammation in cats undergoing onychectomy with ovariohysterectomy or castration.

Dose range finding study for the efficacy of meloxicam administered prior to sodium urate-induced synovitis in cats

OBJECTIVE

To determine the lowest efficacious dose of oral meloxicam for relieving pain in cats with a sodium urate (SU)-induced acute inflammatory synovitis.

STUDY DESIGN

Randomized, blinded, controlled, and four-way crossover study.

ANIMALS

Eight surgically neutered cats (four males, four females) paired according to sex.

METHODS

Each pair of cats was treated with 0 (placebo), 0.025, 0.05, or 0.075 mg kg(-1) oral meloxicam once daily for 4 days prior to injection, into alternating stifles, of 1 mL of 20 mg mL(-1) SU crystals, beginning with the right stifle. Each cat received each of the four treatments, separated by at least 21 days. Analgesic efficacy was evaluated based on objective (e.g., pressure mat data total force, contact pressure, and contact area) and subjective (e.g., scores for Analgesia Scale [AS], Lameness Scale [LS], and Visual Analog Scale [VAS]) outcome measures for pain assessment. All outcome measures were recorded before and during 30 hours after SU injection. The pre-defined primary outcome measure was the area under the response-time curve (AUC(0-30) hours) of the total force of the injected limb. Data were analyzed by analysis of variance. A sequential test procedure was applied and the test sequence stopped in case of a nonsignificant result.

RESULTS

Meloxicam at doses of 0.05 and 0.075 mg kg(-1) day(-1) PO was significantly different from placebo for the pre-defined primary outcome measure (i.e., AUC(0-30) hours of total force). All tested meloxicam doses were lower than placebo for the subjective outcome measures (i.e., AUC(0-30) hours of AS, LS, and VAS).

CONCLUSIONS AND CLINICAL RELEVANCE

The lowest efficacious dose of meloxicam for relieving pain in cats with an SU-induced synovitis was 0.05 mg kg(-1) day(-1) PO according to the pre-defined primary outcome measure. However, lower doses may also be effective as seen in the subjective outcome measures.

Long-term pain in cats: how much do we know about this important welfare issue?

PRACTICAL RELEVANCE

Long-term pain in cats is an important welfare issue but is often overlooked and undertreated.

AUDIENCE

All practitioners are faced with cats that require analgesic intervention to improve their quality of life.

PATIENT GROUP

Any cat may potentially experience long-term pain and discomfort. Degenerative joint disease and diabetic-related pain is more common in middle-aged or older individuals, whereas persistent postsurgical pain can occur at any age and is seen in young cats following onychectomy.

EVIDENCE BASE

Robust evidence on long-term pain issues in cats - specifically, relating to prevalence, etiology, and treatment protocols and outcomes - is missing from the veterinary literature. The aim of this review is to summarise the current state of knowledge. In doing so, it takes a practical approach, highlighting the obvious, and some not so obvious, causes of long-term pain in cats; some aspects that warrant closer attention; our ability to recognize pain and monitor how this impacts on quality of life; and today's treatment options.

Comparison between the analgesic effects of morphine and tramadol delivered epidurally in cats receiving a standardized noxious stimulation

This study compared the analgesic effects of epidural tramadol versus morphine in six healthy cats. Under general anesthesia, each cat received an epidural injection of saline 0.22 ml/kg (control treatment, CT), tramadol 1mg/kg (tramadol treatment, TT), or morphine 0.1mg/kg (morphine treatment, MT). After cats had recovered from anesthesia a simple descriptive scale (SDS), visual analog scale (VAS) and physiological parameters (respiratory and heart rate) were used to assess analgesia level to a noxious stimulus (base of the tail skin fold clamping) at 1, 2, 3, 4, 6, 8, 10, and 12h post-epidural. Group TT had a higher SDS and VAS score when compared to MT at 8, 10 and 12h post-epidural. CT had higher SDS and VAS score at all time points when compared to TT and MT. In conclusion both morphine and tramadol provided analgesia in this model for the first 6h; with epidural morphine resulting in longer lasting analgesia when compared to tramadol.

Analgesic efficacy of perioperative use of vedaprofen, tramadol or their combination in cats undergoing ovariohysterectomy

The analgesic efficacy of tramadol and/or vedaprofen was evaluated in cats submitted for elective ovariohysterectomy, using a randomised double blind placebo controlled design. Forty adult female cats (3.0+/-0.32kg; 1.8+/-0.7 years) were distributed into four groups. Vedaprofen PO (0.5mg/kg), tramadol SC (2mg/kg), both, or placebo was administered 1h before surgery and every 24 and 8h, respectively, for 72h after surgery. Pain score evaluated by interactive visual analogue and composite pain score and hyperalgesia by the von Frey filament test were recorded at 1, 2, 4, 6, 8, 12, 24, 28, 32, 48, 52, 56, 72, 96h and on the 7th day after surgery. Animals treated with combined vedaprofen and tramadol treatment did not need rescue analgesia, did not develop hyperalgesia, and their serum cortisol concentrations and pain scores were lower than placebo until 24 and 72h after surgery, respectively. Combined vedaprofen and tramadol treatment provided more effective postoperative analgesia and prevented hyperalgesia than when used on their own. Multimodal technique is a superior method of treating pain after feline ovariohysterectomy. This work also provides evidence for the benefits of analgesia for up to 3 days following ovariohysterectomy.

Antinociceptive effects of tramadol and acepromazine in cats

Effects of tramadol and acepromazine on pressure and thermal thresholds were examined in eight cats. After baseline measurements, subcutaneous (SC) tramadol 1 mg/kg, acepromazine 0.1 mg/kg, tramadol 1 mg/kg with acepromazine 0.1 mg/kg, or saline 0.3 ml were given. Serial measurements were made for 24 h. Mean thermal thresholds did not change significantly [analysis of variance (ANOVA)] from baseline. The maximum thermal threshold increase above baseline was 2.8+/-2.8 degrees C at 6 h (P>0.05) after tramadol; it was above the 95% confidence interval (CI) at 0.75, 3 and 6 h. Pressure thresholds increased above baseline from 0.25 to 2 h after acepromazine (P<0.05) and from 0.5 to 3 h after the combination (P<0.05), with a maximum increase of 132+/-156 mmHg 0.25 h after acepromazine and 197+/-129 mmHg 0.5 h after the combination. Pressure thresholds were above the 95% CI from 0.25 to 2 h after acepromazine and from 0.5 to 3 h after the combination. SC tramadol at 1 mg/kg in cats had limited effect on thermal and pressure nociception, but this was enhanced by acepromazine. Acepromazine alone had pressure antinociceptive effects.

Recent developments in nonsteroidal antiinflammatory drugs in cats

Pain, particularly chronic pain, is an underestimated ailment in cats. Veterinarians tend to under-diagnose and under-treat pain in this aloof and stoic species. Until recently, there was only one analgesic (i.e., butorphanol) approved in the United States for use in cats; but many analgesics, particularly opioids, have been used extra-label for this purpose. Nonsteroidal antiinflammatory drugs (NSAIDs) have been used sparingly in cats because of safety concerns, which are less of an issue with the newer agents. Meloxicam is the only NSAID labeled for use in cats in the United States, but other agents are available in this country and are labeled for use in cats in other countries.

Behavioral alterations and severity of pain in cats recovering at home following elective ovariohysterectomy or castration

OBJECTIVE

To identify behavioral alterations in client-owned cats recovering at home following elective ovariohysterectomy or castration and determine owner perceptions regarding severity of postoperative pain.

DESIGN

Cohort study. Animals-145 cats undergoing elective ovariohysterectomy (n = 80) or castration (65) at 4 veterinary clinics in Finland.

PROCEDURES

Owners were asked to complete a questionnaire on their cats' behavior during the 3 days after surgery. Owners were also asked to indicate their perceptions of the severity of postoperative pain during these days by use of a 100-mm visual analog scale.

RESULTS

Owners consistently indicated that there were changes in their cats' behavior, with the most commonly reported alterations being a decrease in overall activity level, an increase in the amount of time spent sleeping, a decrease in playfulness, and altered way of movement. Changes (ie, either an increase or decrease) in aggressive behavior were rare. Median pain score the day of surgery was 15.0 mm for male cats and 25.0 mm for female cats. Behavior score was significantly associated with day of observation, type of surgery (ovariohysterectomy vs castration), owner-assigned pain score, and veterinary clinic.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that behavioral alterations can be detected for several days after surgery in cats recovering at home following ovariohysterectomy or castration and emphasized owner concerns about the existence of postoperative pain.

Nonsteroidal anti-inflammatory drugs in cats: a review

OBJECTIVE

To review the evidence regarding the use of nonsteroidal anti-inflammatory drugs (NSAIDs) in cats.

DATABASES USED

PubMed, CAB abstracts.

CONCLUSIONS

Nonsteroidal anti-inflammatory drugs should be used with caution in cats because of their low capacity for hepatic glucuronidation, which is the major mechanism of metabolism and excretion for this category of drugs. However, the evidence presented supports the short-term use of carprofen, flunixin, ketoprofen, meloxicam and tolfenamic acid as analgesics in cats. There were no data to support the safe chronic use of NSAIDs in cats.

Effects of subcutaneous methadone, morphine, buprenorphine or saline on thermal and pressure thresholds in cats

This study compared pressure and thermal thresholds after administration of three opioids in eight cats. Pressure stimulation was performed via a bracelet taped around the forearm. Three ball-bearings were advanced against the forearm by inflation of a modified blood pressure bladder. Pressure in the cuff was recorded at the end point (leg shake and head turn). Thermal threshold was tested as previously reported using a heated probe held against the thorax [Dixon et al. (2002) Research in Veterinary Science, 72, 205]. After baseline recordings, each cat received subcutaneous methadone 0.2 mg/kg, morphine 0.2 mg/kg, buprenorphine 0.02 mg/kg or saline 0.3 mL in a four period cross-over study. Measurements were made at 15, 30, 45 min and 1, 2, 3, 4, 8, 12 and 24 h after the injection. Data were analysed by anova (P<0.05). There were no significant changes in thresholds after saline. Thermal threshold increased at 45 min after buprenorphine (maximum 2.8+/-3 degrees C), 1-3 h after methadone (maximum 3.4+/-1.9 degrees C) and 45 min to 1 h (maximum 3.4+/-2 degrees C) after morphine. Pressure threshold increased 30-45 min (maximum 238+/-206 mmHg) after buprenorphine, 45-60 min after methadone (maximum 255+/-232 mmHg) and 45-60 min and 3-6 h (maximum 255+/-232 mmHg) after morphine. Morphine provided the best analgesia, and methadone appears a promising alternative. Buprenorphines limited effect was probably related to the subcutaneous route of administration. Previously, buprenorphine has produced much greater effects when given by other routes.