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Animals : an open access journal from MDPI2025; 15(4); 571; doi: 10.3390/ani15040571

Analgesic and Gastrointestinal Effects of Morphine in Equines.

Abstract: Morphine has significant clinical and analgesic effects in horses, but its impact on the gastrointestinal tract requires further understanding. This study assessed the analgesic and gastrointestinal effects of morphine in horses undergoing elective orchiectomy in the quadrupedal position. Thirty uncastrated male horses were randomly assigned to three groups: orchiectomy without morphine and sedation protocol (OSM), orchiectomy with morphine and sedation protocol (OM), and administration of morphine alone in the absence of orchiectomy (M). The anesthetic protocol involved acepromazine (0.05 mg/kg IV) and detomidine (10 mcg/kg IV) sedation in groups OSM and OM, with morphine sulfate (0.05 mg/kg IV) given to OM and M, and NaCl to OSM. The team measured clinical parameters, pain, and sedation using the EQUUS-FAP scale, while they monitored bowel motility and gastric dilation through abdominal ultrasound. These assessments were performed on the previous day (m1), 20 min before surgery (m2), and at various time points following the administration of morphine or saline solution: one hour (m3), two hours (m4), four hours (m5), six hours (m6), and eight hours (m7) post-procedure for all three groups. There was no significant difference in pain score between OSM and OM, though OM had better sedation. Ultrasound revealed decreased colon contractions and minor gastric dilation in OSM and OM, normalizing within 6 h. Group M showed reduced motility and significant gastric dilation lasting 8 h. In conclusion, while morphine enhanced sedation without causing greater gastrointestinal dysfunction than OSM, its administration alone resulted in a more pronounced reduction in gastrointestinal motility and an increased risk of gastric dilation.
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Publication Date: 2025-02-17 PubMed ID: 40003052PubMed Central: PMC11851385DOI: 10.3390/ani15040571Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The researchers explored the effects of morphine on pain relief and gastrointestinal function in horses undergoing surgical castration. The results indicated that morphine can effectively enhance sedation in this context, without causing significant adverse effects on the digestive system. However, when morphine was given on its own, it reduced gastrointestinal motility and increased the risk of stomach expansion.

Study Design

  • The study was conducted on 30 uncastrated male horses that were randomly divided into three groups.
  • The first group (OSM) underwent surgical castration without being given morphine, but was given a sedation protocol involving two other drugs.
  • The second group (OM) also underwent surgical castration but was given both morphine and the same sedation protocol as the first group.
  • The third group (M) was given morphine alone, without undergoing the surgical procedure.

Methodology

  • The sedation protocol in the study involved the use of two drugs, acepromazine and detomidine, which were administered intravenously to the first two groups of horses.
  • Morphine was also given intravenously to the second and third groups, while the first group received a saline solution instead.
  • The researchers used a specialized scale known as the EQUUS-FAP to measure clinical parameters, levels of pain, and sedation in the horses.
  • The functioning and movements of the horses’ intestines were monitored using abdominal ultrasound, and this method was also used to detect signs of stomach dilation.

Findings

  • The results showed that the levels of pain experienced by the horses in the first and second groups (OSM and OM) were not significantly different.
  • However, the second group (OM), which was given morphine as part of its pain relief protocol, exhibited better sedation than the first group (OSM).
  • The ultrasound observations revealed that the horses in these two groups showed decreased intestinal movements and minor signs of stomach dilation, which returned to normal levels within six hours after the procedure.
  • On the other hand, the third group of horses (M), which was given morphine alone, showed reduced gastrointestinal motility and significant stomach dilation, which lasted for eight hours.

Conclusion

  • Morphine can enhance sedation in the context of equine surgical castration without causing any greater disruption to the digestive system than surgical castration without morphine.
  • However, when morphine is administered on its own, it can reduce the movements of the digestive system and increase the risk of stomach expansion, which were more pronounced and lasted longer than when morphine was administered alongside a surgical procedure.

Cite This Article

APA
Guzmán JFC, Gontijo AS, Melgaço ES, Faria SA, Baldi MLC, Sousa LN, Wenceslau RR, Fantini P, Xavier ABDS, Beier SL. (2025). Analgesic and Gastrointestinal Effects of Morphine in Equines. Animals (Basel), 15(4), 571. https://doi.org/10.3390/ani15040571

Publication

Animals : an open access journal from MDPI
ISSN: 2076-2615
NlmUniqueID: 101635614
Country: Switzerland
Language: English
Volume: 15
Issue: 4
PII: 571

Researcher Affiliations

Guzmán, Juan Felipe Colmenares
  • Clinics and Veterinary Surgery Department, Veterinary School, Minas Gerais State Federal University, UFMG, Belo Horizonte 31270-901, MG, Brazil.
Gontijo, Amaranta Sanches
  • Clinics and Veterinary Surgery Department, Veterinary School, Minas Gerais State Federal University, UFMG, Belo Horizonte 31270-901, MG, Brazil.
Melgaço, Emanuel de Sousa
  • Clinics and Veterinary Surgery Department, Veterinary School, Minas Gerais State Federal University, UFMG, Belo Horizonte 31270-901, MG, Brazil.
Faria, Samuel Andrade
  • Clinics and Veterinary Surgery Department, Veterinary School, Minas Gerais State Federal University, UFMG, Belo Horizonte 31270-901, MG, Brazil.
Baldi, Maria Luiza Castilho
  • Clinics and Veterinary Surgery Department, Veterinary School, Minas Gerais State Federal University, UFMG, Belo Horizonte 31270-901, MG, Brazil.
Sousa, Lara Nunes
  • Clinics and Veterinary Surgery Department, Veterinary School, Minas Gerais State Federal University, UFMG, Belo Horizonte 31270-901, MG, Brazil.
Wenceslau, Raphael Rocha
  • Clinics and Veterinary Surgery Department, Veterinary School, Minas Gerais State Federal University, UFMG, Belo Horizonte 31270-901, MG, Brazil.
Fantini, Priscila
  • Clinics and Veterinary Surgery Department, Veterinary School, Minas Gerais State Federal University, UFMG, Belo Horizonte 31270-901, MG, Brazil.
Xavier, Andressa Batista da Silveira
  • Clinics and Veterinary Surgery Department, Veterinary School, Minas Gerais State Federal University, UFMG, Belo Horizonte 31270-901, MG, Brazil.
Beier, Suzane Lilian
  • Clinics and Veterinary Surgery Department, Veterinary School, Minas Gerais State Federal University, UFMG, Belo Horizonte 31270-901, MG, Brazil.

Grant Funding

  • Coordenau00e7u00e3o de Aperfeicoamento de Pessoal de Nu00edvel Superior

Conflict of Interest Statement

The authors declare no conflicts of interest. The funders had no role in the design of this study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

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