Case report
Adverse reactions after orange essential oil administration to lambs

https://doi.org/10.1016/j.vprsr.2021.100593Get rights and content

Highlights

  • An oral orange essential oil (OEO) formulation was administered to lambs.

  • After doses of 200 mg/kg, 300 mg/kg and 600 mg/kg lambs showed adverse reactions.

  • The most common clinical signs observed were head shaking, backward head movement, and ataxia.

  • With dose of 600 mg/kg lambs showed more severe clinical signs and longer duration of symptoms.

Abstract

The major compound in orange essential oil (OEO) is limonene, which has in vitro anthelmintic properties; however, a safe in vivo dose has not been defined for animals. Therefore, a pilot study was conducted to evaluate the effect of an OEO formulation for the control of gastrointestinal nematodes in sheep and to investigate adverse reactions in lambs after OEO administration. A total of 17 lambs received an oral OEO formulation at a concentration of 600 mg/mL, in doses of 200, 300, and 600 mg/kg. The most common clinical signs observed were head shaking (88.8%), backward head movement (51.1%), and ataxia (74.4%). Lambs treated with 600 mg/kg of OEO showed more severe combined clinical signs and longer duration of symptoms, presenting adverse reactions for up to 2 h after OEO administration. Testing of different doses and formulations with slower release of the active ingredient is recommended to minimize or eliminate these effects.

Introduction

Orange essential oil (OEO) mainly comprises limonene (Gaínza et al., 2015) which represents approximately 95% of its composition (Vora et al., 1983; Bermejo et al., 2011). Limonene is one of the most common monoterpenes found in essential oils from Citrus trees, belonging to the family Rutaceae.

Some publications suggest the use of OEO to control gastrointestinal nematodes (GIN) in sheep. In vitro and in vivo studies have reported promising results when OEO was used for this purpose (Squires et al., 2010; Gaínza et al., 2015). However, Squires et al. (2010) mentioned that some of the lambs that received the OEO presented head shaking and lack of appetite, and that these behaviors persisted for a maximum of 20 min.

A pilot study was conducted to evaluate the effectiveness of an OEO formulation for the control of GIN in sheep. Adverse reactions were very evident post OEO administration and this case report provides warning regarding the peracute side effects that may occur with the therapeutic use of OEO in sheep.

Section snippets

Case presentation

The pilot study was conducted in July 2019 at the sheep farming sector of the Gralha Azul Experimental Farm of the Pontifical Catholic University of Paraná.

The objective of this pilot study was to test different formulations of a commercial OEO (Óleo Essencial de Laranja; Dica Comercial Ltda, Canoas, Brazil) for viscosity, and concentration, as well as the ease of oral administration. The main project was approved by the Ethics Committee on the Use of Animals of the Pontifical Catholic

Discussion

The lipophilicity and low molecular weight of terpenes makes these compounds of interest to the health sector, as these combined pharmacokinetic properties favor manipulation and transformation into medications (Vieira et al., 2018).

Limonene (97% purity) formulated in 400 mg capsules for oral administration in humans is considered safe when used in single or daily doses between 8 and 12 g/(m2 day) for 21 days, as it has low toxicity (Vigushin et al., 1998). Limonene is reported to have no

Conclusion

OEO administration to lambs at doses between 200 and 600 mg/kg caused adverse reactions. Lambs treated with 600 mg/kg showed more severe combined clinical signs and lambs treated with lower doses showed signs with shorter duration.

This case report describes the clinical signs caused by OEO ingestion and the approximate time for the animals to return to their normal condition. Thus, this report serves as a warning regarding the observed side effects and helps in designing future research for

Funding

This work was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) – Brazil – Finance Code 001.

Declaration of competing interest

None of the authors have any conflict of interest to declare.

Acknowledgements

We would like to acknowledge Francineia Souza (Dexter Latina) for orange essential oil formulations.

References (22)

Cited by (4)

  • Phytochemical modulation of P-Glycoprotein and its gene expression in an ivermectin-resistant Haemonchus contortus isolate in vitro

    2022, Veterinary Parasitology
    Citation Excerpt :

    Studies suggest that the action of compounds such as those mentioned above occurs synergistically with each other; so, it would be feasible to assume that their combined use in animals would produce better bioactivity than when used separately. Although there are some studies involving the anthelmintic activity of phytochemicals (Katiki et al., 2017; Katiki et al., 2011) against H. contortus in vitro and some in vivo (Squires et al., 2010; Silva et al., 2021), we did not find any studies involving the exact mechanism of action of these phytochemicals in H. contortus. However, compounds such as limonene have been reported to modulate the function of human nicotinic acetylcholine receptors (Lozon et al., 2016).

  • Can orange essential oil reduce the severity of parasitic infection in sheep?

    2021, Veterinary Parasitology: Regional Studies and Reports
    Citation Excerpt :

    However, there were some adverse reactions due to OEO intake in the pilot study, such as head shaking, backward head movement, and ataxia. The highest dose (600 mg/kg) resulted in more clinical signs, which were occasionally more intense and long lasting (da Silva et al., 2021). Therefore, initially, lower doses were tested to minimize these signs while maintaining the percentage of parasitic load reduction.

View full text