Effects of methadone, alone or in combination with acepromazine or xylazine, on sedation and physiologic values in dogs

Objective To evaluate the effects of methadone, administered alone or in combination with acepromazine or xylazine, on sedation and on physiologic values in dogs.Study design Randomized cross-over design.Animals Six adult healthy mixed-breed dogs weighing 13.5 +/- 4.9 kg.Methods Dogs were injected intramuscularly with physiologic saline (Control), or methadone (0.5mg kg(-1)) or acepromazine (0.1 mg kg(-1)) or xylazine (1.0 mg kg(-1)), or acepromazine (0.05 mg kg(-1)) plus methadone (0.5 mg kg(-1)) or xylazine (0.5 mg kg(-1)) plus methadone (0.5 mg kg(-1)) in a randomized cross-over design, with at least 1-week intervals. Sedation, pulse rate, indirect systolic arterial pressure, respiratory rate (RR), body temperature and pedal withdrawal reflex were evaluated before and at 15-minute intervals for 90 minutes after treatment.Results Sedation was greater in dogs receiving xylazine alone, xylazine plus methadone and acepromazine plus methadone. Peak sedative effect occurred within 30 minutes of treatment administration. Pulse rate was lower in dogs that received xylazine either alone or with methadone during most of the study. Systolic arterial pressure decreased only in dogs receiving acepromazine alone. When methadone was administered alone, RR was higher than in other treatments during most of the study and a high prevalence of panting was observed. In all treatments body temperature decreased, this effect being more pronounced in dogs receiving methadone alone or in combination with acepromazine. Pedal withdrawal reflex was absent in four dogs receiving methadone plus xylazine but not in any dog in the remaining treatments.Conclusions Methadone alone produces mild sedation and a high prevalence of panting. Greater sedation was achieved when methadone was used in combination with acepromazine or xylazine. The combination xylazine-methadone appears to result in better analgesia than xylazine administered alone. Both combinations of methadone/sedative were considered effective for premedication in dogs.

Comparison of decompressive surgery, electroacupuncture, and decompressive surgery followed by electroacupuncture for the treatment of dogs with intervertebral disk disease with long-standing severe neurologic deficits

Objective To compare the effects of decompressive surgery (DSX), electroacupuncture (EAP), and DSX followed by EAP (DSX + EAP) for the treatment of thoracolumbar intervertebral disk disease (IVDD) in dogs with severe neurologic deficits of > 48 hours' duration.Design Retrospective case series and prospective clinical trial.Animals-40 dogs between 3 and 6 yEAPs old and weighing between 10 and 20 kg (22 and 44 lb) with long-standing (>48 hours) clinical signs of severe neurologic disease attributable to thoracolumbar IVDD.Procedures Thoracolumbar medullar injury was classified on the basis of neurologic signs by use of a scale ranging from 1 (least severe) to 5 (most severe). The DSX dogs (n = 10) were retrospectively selected from those that underwent DSX for the treatment of thoracolumbar IVDD. In addition, 19 dogs received EAP alone and 11 dogs underwent DSX followed by EAP (DSX + EAP). Outcome was considered a clinical success when a dog initially classified as grade 4 or 5 was classified as grade 1 or 2 within 6 months after the end of treatment.Results The proportion of dogs with clinical success was significantly higher for dogs that underwent EAP (15/19) than for dogs that underwent DSX (4/10); the proportion of dogs with clinical success for dogs that underwent DSX + EAP was intermediate (8/11).Conclusions and Clinical Relevance EAP was more effective than DSX for recovery of ambulation and improvement in neurologic deficits in dogs with long-standing severe deficits attributable to thoracolumbar IVDD. (J Am Vet Med Assoc 2010;236:1225-1229)

Effects of the opiold remifentanil on the arrhythmogenicity of epinephrine in halothane-anesthetized dogs

Opioids may exert a protective effect against ventricular arrhythmias via a vagally mediated mechanism. This study evaluated the effects of the opioid remifentanil on arrhythmogenicity of epinephrine during halothane anesthesia. Eight dogs were assigned to 2 treatments in a randomized crossover design, with 1-week intervals between treatments. Anesthesia was maintained with 1.3% end-tidal halothane in oxygen and mechanical ventilation to maintain eucapnia. A constant rate infusion of remifentanil (0.72 mu g/kg/min) was administered throughout the study in the experimental treatment, while control animals received physiologic saline as placebo. The arrhythmogenic dose of epinephrine (ADE), defined as 4 premature ventricular complexes (PVCs) within 15 s, was determined by administering progressively increasing infusion rates of epinephrine (2.5, 5.0, and 10 mu g/kg/min), allowing 20 min intervals between each infusion rate. In both treatments, epinephrine infusions induced bradyarrhythmias and atrioventricular conduction disturbances, which were followed by escape beats and PVCs. In the remifentanil treatment, mean s ADE values (11.3 +/- 4.9 mu g/kg) did not differ from values observed in control animals (9.9 +/- 6.1 mu g/kg). on the basis of the ADE model for assessing the arrhythmogenity of drugs during halothane anesthesia, the present study did not demonstrate a protective effect of remifentanil (0.72 mu g/kg/min) against ventricular arrhythmias in dogs.

Post-operative analgesic effects of butorphanol or firocoxib administered to dogs undergoing elective ovariohysterectomy

ObjectiveTo compare the post-operative analgesic effects of butorphanol or firocoxib in dogs undergoing ovariohysterectomy.Study designProspective, randomized, blinded, clinical trial.AnimalsTwenty-five dogs > 1 year of age.MethodsDogs received acepromazine intramuscularly (IM), 0.05 mg kg-1 and either butorphanol IM, 0.2 mg kg-1 (BG, n = 12) or firocoxib orally (PO), 5 mg kg-1 (FG, n = 13), approximately 30 minutes before induction of anesthesia with propofol. Anesthesia was maintained with isoflurane. Ovariohysterectomy was performed by the same surgeon. Pain scores using the dynamic and interactive visual analog scale (DIVAS) were performed before and at 1, 2, 3, 4, 6, 8 and 20 hours after the end of surgery by one observer, blinded to the treatment. Rescue analgesia was provided with morphine (0.5 mg kg-1) IM and firocoxib, 5 mg kg-1 (BG only) PO if DIVAS > 50. Groups were compared using paired t-tests and Fisher's exact test (p < 0.05). Data are presented as mean +/- SD.ResultsThe BG required significantly less propofol (BG: 2.6 +/- 0.59 mg kg-1; FG: 5.39 +/- 0.7 mg kg-1) (p < 0.05) but the anesthesia time was longer (BG: 14 +/- 6, FG: 10 +/- 4 minutes). There were no differences for body weight (BG: 7.9 +/- 5.0, FG: 11.5 +/- 4.6 kg), sedation scores, and surgery and extubation times (BG: 10 +/- 2, 8 +/- 5 minutes; FG: 9 +/- 3, 8 +/- 4 minutes, respectively) (p > 0.05). The FG had significantly lower pain scores than the BG at 1, 2 and 3 hours following surgery (p < 0.05). Rescue analgesia was administered to 11/12 (92%) and 2/13 (15%) dogs in the BG and FG, respectively (p < 0.05).Conclusion and clinical relevanceFirocoxib produced better post-operative analgesia than butorphanol. Firocoxib may be used as part of a multimodal analgesia protocol but may not be effective as a sole analgesic.

Hemodynamic effects in dogs anesthetized with isoflurane and remifentanil-isoflurane

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Comparison of the cardio-respiratory effects of methadone and morphine in conscious dogs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Electroacupuncture analgesia in dogs: is there a difference between uni- and bi-lateral stimulation?

Objective To compare the analgesic effect of uni- and bi-lateral electroacupuncture (EA) in response to thermal and mechanical nociceptive stimuli and to investigate the cardiorespiratory, endocrine, and behavioral changes in dogs submitted to EA.Study design Prospective, randomized cross-over experimental study.Animals Eight adult, clinically healthy, cross-breed dogs, weighing 13 +/- 4 kg.Methods Dogs underwent electrostimulation at false acupoints (T-false); bilateral EA at acupoints, stomach 36, gall bladder 34 and spleen 6 (T-EA/bil); unilateral EA at the same points (T-EA/uni) or were untreated (T-control). All animals received acepromazine (0.05 mg kg(-1)) IV; and heart rate, pulse oximetry, indirect arterial blood pressure, respiratory rate, PECO2, rectal temperature, and plasma cortisol concentration were measured before, during, and after EA. Analgesia was tested using thoracic and abdominal cutaneous thermal and mechanical stimuli, and an interdigital thermal stimulus. Behavior was classified as calm or restless. Analysis of variance for repeated measures followed by Tukey's test was used for analysis of the data.Results There were no cardiorespiratory differences among the treatments. The cutaneous pain threshold was higher after EA, compared with false points. The latency period was shorter and analgesia was more intense in T-EA/bil than T-EA/uni, when both were compared with T-false and T-control. Six out of eight animals treated with EA were calm during treatment, and 5/8 and 4/8 of the T-false and T-control animals, respectively, were restless. Latency to interdigital thermal stimulation increased in T-EA/bil compared with the others. There was no difference in plasma cortisol concentrations among the treatments.Conclusions Bilateral EA produced a shorter latency period, a greater intensity, and longer duration of analgesia than unilateral stimulation, without stimulating a stress response.Clinical relevance Bilateral EA produces a better analgesic effect than unilateral EA.

Effect of remifentanil on requirements for propofol administered by use of a target-controlled infusion system for maintaining anesthesia in dogs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of intravenous propofol and remifentanil on heart rate, blood pressure and nociceptive response in acepromazine premedicated dogs

ObjectiveTo investigate the cardiorespiratory, nociceptive and endocrine effects of the combination of propofol and remifentanil, in dogs sedated with acepromazine.Study designProspective randomized, blinded, cross-over experimental trial.AnimalsTwelve healthy adult female cross-breed dogs, mean weight 18.4 +/- 2.3 kg.MethodsDogs were sedated with intravenous (IV) acepromazine (0.05 mg kg-1) followed by induction of anesthesia with IV propofol (5 mg kg-1). Anesthesia was maintained with IV propofol (0.2 mg kg-1 minute-1) and remifentanil, infused as follows: R1, 0.125 mu g kg-1 minute-1; R2, 0.25 mu g kg-1 minute-1; and R3, 0.5 mu g kg-1 minute-1. The same dogs were administered each dose of remifentanil at 1-week intervals. Heart rate (HR), mean arterial pressure (MAP), respiratory rate (f(R)), end tidal CO(2) (Pe'CO(2)), arterial hemoglobin O(2) saturation, blood gases, and rectal temperature were measured before induction, and 5, 15, 30, 45, 60, 75, 90, and 120 minutes after beginning the infusion. Nociceptive response was investigated by electrical stimulus (50 V, 5 Hz and 10 ms). Blood samples were collected for plasma cortisol measurements. Statistical analysis was performed by anova (p < 0.05).ResultsIn all treatments, HR decreased during anesthesia with increasing doses of remifentanil, and increased significantly immediately after the end of infusion. MAP remained stable during anesthesia (72-98 mmHg). Antinociception was proportional to the remifentanil infusion dose, and was considered satisfactory only with R2 and R3. Plasma cortisol concentration decreased during anesthesia in all treatments. Recovery was smooth and fast in all dogs.Conclusions and clinical relevanceInfusion of 0.25-0.5 mu g kg-1 minute-1 remifentanil combined with 0.2 mg kg-1 minute-1 propofol produced little effect on arterial blood pressure and led to a good recovery. The analgesia produced was sufficient to control the nociceptive response applied by electrical stimulation, suggesting that it may be appropriate for performing surgery.

CYR61, a cellular proliferation marker in dogs with prostatic disease

The life expectancy of dogs is increasing and is associated with a greater frequency of age-related disease, including that of the prostate gland. A marker of cell proliferation, CYR61, may be detected in a number of conditions in humans, including hyperplasia and neoplasia. The objective of the present study was to investigate the degree of CYR61 expression in a number of different prostate diseases in dogs in order to understand the potential of this marker for diagnosis of prostatic disease. Immunohistochemistry with a CYR61 antibody was performed on prostatic tissue from 22 dogs with different diseases. Intense stromal staining was observed in cases of prostatic dysplasia and benign prostate hyperplasia. In contrast, CYR61 staining was very intense in alveolar epithelial cells in cases of epithelial benign prostate hyperplasia and one case of adenocarcinoma. An obvious CYR61 staining pattern was absent in cases of prostatitis. In conclusion, CYR61 may be a useful marker of cell proliferation in a number of prostatic pathologies, although further studies of normal tissue are warranted. (c) 2006 Elsevier B.V. All rights reserved.

Acute bacterial cystitis does not cause deoxyribonucleic acid damage detectable by the alkaline comet assay in urothelial cells of dogs

Considering the high incidence of dogs with acute bacterial cystitis (BC) and the relationship among inflammation, genotoxicity, and carcinogenesis, we conducted a case-control study comparing the frequency of deoxyribonucleic acid (DNA) lesions assessed by the comet assay between disease-free animals (13 males and 13 females) and cytology-confirmed cases of acute BC (12 males and 12 females), which was mainly caused by Staphylococcus sp. (40%) and Escherichia coli (35%). The results show no increase in DNA damage in cells obtained by bladder washings and no influence of age, sex, and breed due to acute BC. In conclusion, DNA damage was seemingly not associated with the infection by specific bacteria.

Molecular characterization of Giardia duodenalis in dogs from Brazil

The intestinal protozoan parasite Giardia duodenalis (syn. Giardia intestinalis and Giardia lamblia) is a widespread enteric pathogen in human and domestic animals. This organism is one of the most common parasites in domestic dogs in Brazil. In this study, we determined the occurrence and genetic characterization of G. duodenalis isolated from dogs from south-central São Paulo state, Brazil. A total of 300 fecal samples were collected. Fecal specimens were screened for the presence of G. duodenalis using microscopy (zinc sulfate solution flotation technique) and polymerase chain reaction (PCR) targeting the small subunit ribosomal (SSU-rDNA) and glutamate dehydrogenase (GDH) genes. Genetic characterization was performed using restriction fragment length polymorphisms (RFLP) and sequencing analysis of the GDH gene. In addition, selected samples were further characterized by RFLP and sequencing of the beta-giardin gene. The overall occurrence of G. duodenalis was 17.3% (52/300). The occurrence was higher in stray dogs (28%) than in household dogs (6.25%). of the 36 PCR-positive samples that were selected for genotyping, only dog-specific genotype C (20 isolates), D (11 isolates) and mixed C+D (five isolates) isolates were detected in the study. This study provides current information on the infection rates of G. duodenalis genotypes in canine populations and describes for the first time the presence of mixed infections within host-specific C and D genotypes in dogs in Brazil. These genotypes were widespread and commonly found in domestic dogs living in urban and suburban environments of the studied area and confirmed the endemic status of Giardia in this region.

Prevalence of von Willebrand disease in dogs from São Paulo State, Brazil

The aims of the current study were to assess the prevalence of von Willebrand disease (vWD) in dogs from the region of Botucatu, São Paulo State, Brazil, and to evaluate laboratory tests to diagnose this disease. The study included 350 dogs of various ages, different breeds, and both sexes. Dogs included in the study had no historical or clinical evidence of abnormal bleeding. von Willebrand factor antigen (vWF:Ag), buccal mucosal bleeding time, activated partial thromboplastin time, and factor VIII activity were evaluated in their ability to diagnose vWD. The prevalence of vWD in dogs was 1.43% in the Botucatu region of Brazil. Determination of vWF:Ag was the best laboratory test to diagnose vWD.

Clinical and electrocardiographic evaluation during experimental toad poisoning in dogs

Accidents involving toad poisoning are frequent and dogs are the most common victims; they become poisoned by biting or ingesting a toad. When released in the organism, the venom is absorbed by both the oral mucosa and the digestive tract, initiating its toxic action. The aim of this work was to evaluate the clinical and electrocardiographic aspects of dogs subjected to experimental toad poisoning, as well as their response to treatment with propranolol. Twenty dogs were divided into two groups, a control group (n = 5) and a poisoned group (n = 15). After general anesthesia, the control group received a placebo, while the poisoned group received a venom aliquot through an orogastric tube. Results were tested through multivariate analysis (p < 0.05). The animals in the poisoned group had gastrointestinal symptoms including emesis, intense salivation, hyperemic or congested oral mucosa and pasty diarrhea. Non-responsive mydriasis, nystagmus, depression, stupor, tachypnea, opisthotonus and ataxia were also manifested by 100% of the poisoned animals. Affected dogs had an increase in blood pressure, statistically significant throughout study. Five poisoned animals developed ventricular tachycardia and were treated with propranolol (0.5 mg/kg IV). All propranolol-treated animals returned to normal sinus rhythm, which evidences the efficacy of this drug to treat ventricular arrhythmias caused by toad venom.

Toad poisoning in three dogs: case reports

Toad poisoning is frequent in dogs, but has been infrequently addressed in published case reports and review articles. Dogs can be poisoned when they bite a toad or otherwise ingest the venom. The venom effects manifest soon after the accident, since the toxin is rapidly absorbed by the mucous membrane of the digestive system. Hospital records of three dogs, diagnosed with toad poisoning, were retrospectively reviewed from January 2005 to July 2007. Poisoned dogs may present only local irritation or systemic signs in the gastrointestinal, cardiac and neurological systems. All three cases presented herein had clinical signs of gastrointestinal alterations including vomiting, sialorrhea and diarrhea. Two dogs developed abnormal cardiac rhythm and two exhibited neurological signs. A poisoned animal requires emergency care and symptomatic therapy with intense monitoring of its clinical parameters. Although there have been reports on the low mortality of dogs poisoned by toads, one animal died even after appropriate therapy. The severity of clinical signs and the risk of death must be considered by the veterinarian.