Effects of preanesthetic administration of metamizole on renal function, blood parameters and bone marrow cells in healthy dogs

Pain Management and Analgesics Used in Small Mammals during Post-Operative Period with an Emphasis on Metamizole (Dipyrone) as an Alternative Medication

Metamizole (dipyrone) is a widely used non-opioid analgesic in both human and animal medicine. Metamizole's safety has been the topic of numerous opposing debates, given the fact that in certain countries metamizole is frequently used as an over-the-counter (OTC) medicine, while in others it is banned due to the risk of agranulocytosis. Further, small mammals such as rabbits, ferrets, rodents, and hedgehogs have become some of the most common pets present in veterinary practice, and each of these species has specific analgesic needs due to their anatomy and physiology. The key to providing appropriate medical care is in finding a substance that has minimal negative effects. In small mammals, analgesia is an important factor and, it happens frequently that, pain in these patients is not well managed. Post-operative pain management is an important topic in the welfare of animals. The objectives of this review, thus, were to provide a concise overview of analgesics that are used in the treatment of postoperative pain in small mammals (e.g., rabbits and rodents) and to highlight the importance of this product, metamizole, in veterinary medicine, as well as the potential of this substance as an alternative analgesic for the treatment of postoperative pain in small mammals.

Cyclooxygenases 1 and 2 inhibition and analgesic efficacy of dipyrone at different doses or meloxicam in cats after ovariohysterectomy

OBJECTIVE

To evaluate the cyclooxygenases (COX) inhibition, adverse effects and analgesic efficacy of dipyrone or meloxicam in cats undergoing elective ovariohysterectomy.

STUDY DESIGN

Prospective, blinded, randomized, clinical study.

ANIMALS

A total of 30 healthy young cats.

METHODS

The cats were randomly assigned to three postoperative groups: D25 (dipyrone 25 mg kg^-1 every 24 hours), D12.5 (dipyrone 12.5 mg kg^-1 every 12 hours) and M (meloxicam 0.1 mg kg^-1 every 24 hours). In the first 24 hours, the drugs were administered intravenously (IV), and then orally for 6 (dipyrone) or 3 days (meloxicam). Prostanoids thromboxane B₂ and prostaglandin E₂ concentrations served as indicators of COX activity and, with physiological variables and pain and sedation scores, were measured for 24 hours after first analgesic administration. Rescue analgesia (tramadol, 2 mg kg^-1 IV) was provided if Glasgow feline composite measure pain scale (CMPS-Feline) ≥5. Laboratory tests included symmetric dimethylarginine and adverse effects were evaluated regularly up to 7 and 10 days after surgery, respectively. Parametric and nonparametric data were analyzed with two-way anova and Kruskal-Wallis tests, respectively (p < 0.05).

RESULTS

In the first half hour after analgesic administration, COX-1 activity was close to zero and remained significantly lower than before drug administration for 24 hours in all groups. The inhibition of COX-2 activity was significant for 30 minutes in all groups and up to 4 hours in group M. No alterations in laboratory tests or significant adverse effects were observed. Pain scores and need for rescue analgesia did not differ statistically among groups.

CONCLUSIONS

Dipyrone at both doses and meloxicam provided a nonselective inhibition of COX-1 and -2 activities and effective analgesia without causing significant adverse effects or laboratory tests alterations.

CLINICAL RELEVANCE

Dipyrone at both doses provides equally effective analgesia without causing adverse effects in cats undergoing ovariohysterectomy.

Evaluation of postoperative pain and toxicological aspects of the use of dipyrone and tramadol in cats

OBJECTIVES

The aim of this study was to evaluate the effects of dipyrone and tramadol, used for 5 days, on postoperative pain, hematological and biochemical parameters, and oxidative markers on erythrocytes.

METHODS

Twenty-eight healthy cats underwent ovariohysterectomy and were randomly allocated to four groups (each n = 7), according to the postoperative treatment administered intravenously: control (saline 1 ml q8h), DIP1 (dipyrone 25 mg/kg q24h), DIP2 (dipyrone 25 mg/kg q12h) and DIP3 (dipyrone 25 mg/kg q8h). All animals received tramadol (2 mg/kg q8h). Pain was assessed by visual analog (VAS), multidimensional UNESP and Glasgow pain scales for cats preoperatively and at 3, 6, 12, 24, 36 and 48 h after extubation. Venous blood was collected daily for 5 days, and on day 10, to perform a complete blood count (CBC) and determine the percentage of Heinz bodies (HBs). Serum biochemistry was evaluated preoperatively and on days 5 and 10; superoxide dismutase (SOD), catalase (CAT), myeloperoxidase (MPO) and lipoperoxidation were evaluated preoperatively and on days 3, 5 and 10.

RESULTS

Control cats had higher pain scores than DIP3 cats by UNESP (P = 0.0065), and DIP2 (P = 0.0035) and DIP3 cats (P = 0.0108) by VAS 3 h postoperatively. Rescue analgesia was required by two animals in the control group and one each in the DIP1 and DIP2 groups. There was no difference in SOD or CAT among groups. On day 5, MPO was more active in DIP2 than in DIP3 cats (P = 0.0274). No difference in lipoperoxidation among treatment and control cats was found. CBC remained constant and without statistical difference among groups. Control, DIP2 and DIP3 cats presented a similar percentage of HBs on day 10. Biochemical variables were similar among groups and times.

CONCLUSIONS AND RELEVANCE

The administration of dipyrone in cats, when used in combination with tramadol, did not ensure better analgesia than tramadol alone. Dipyrone did not significantly affect biochemical variables and oxidative markers, despite minimal, clinically irrelevant, hematological differences between groups.