## 7 Safety Considerations of Essential Oils  
While EOs have gained popularity, a major concern lies in the limited studies on their toxicity [119]. The potentially harmful effects of EOs and their components are typically assessed in lab animals like rodents. Initial tests on rats have shown that most EOs have low toxicity, with an LD50 range of 1-20 g/kg [120]. However, studies examining their effects on the host are scarce.  
Preliminary toxicity tests on peppermint EO (_M. piperita_) in sheep demonstrated no adverse effects on behavior, blood parameters, or kidney and liver functions. It indicates the safety of using the formulation on sheep, especially in the short term [96]. Similar resultswere observed for lemongrass EO _Cymbopogon schoenanthus_ L. (_C. schoenanthus_) applied to sheep at doses of 180 and 360 mg/kg orally [121] and for the encapsulated combination of anethole and carvone applied to lambs at doses of 20 and 50 mg/kg orally [122]. In both cases, there were no toxic effects on animal behavior or liver and kidney functions, affirming their safety [121; 122].  
Studies demonstrate that pesticides classified as having minimal risk and not registered with the Environmental Protection Agency (EPA) can have notable detrimental effects on dogs and cats. Among the exposed animals, most (92%) exhibited symptoms after using naturally derived plant flea products. It's worth noting that even when labeled as \"natural\" and applied according to the instructions, these minimal-risk pesticides may still have adverse effects on animals [23]. Furthermore, individual animals may display varying sensitivity to EOs due to their distinct host characteristics [23; 123].  
In a study, pets infested with fleas were thoroughly treated with an infusion derived from _Melissa officinalis_ (_M. officinalis_) (prepared as a decoction) for 30 min. The animals' coats were allowed to air dry after this treatment. Additionally, alternative formulations, including a spray made from _Citrus_ spp. (prepared as a decoction), _L. officinalis_ (also prepared as a decoction), and EOs from _Thuja plicata_ (_T. plicata_) and _Juniperus communis_ (_J. communis_), were employed against the fleas [124]. In all trials, effective repellence was observed 24 h after treatment. However, the study did not provide information regarding the percentage of infestation post-treatment, which consequently hindered the determination of overall efficacy [124].  
Utilizing botanical anthelmintics presents various benefits. These include their diverse chemical composition, comprising compounds from different chemical groups, which reduces the likelihood of resistance development. Additionally, their natural origin leads to fewer residues in animal products and the environment, making them an economically viable option [59; 125; 126; 127]. Furthermore, employing an encapsulation technique can enhance the in vivo effectiveness of EO by safeguarding its active components from degradation, thus increasing their availability [128].  
Alternatively, better outcomes can be attained by augmenting the dosage or administering multiple doses over consecutive days instead of a single application. However, assessing the potential toxicity when employing higher doses or multiple administrations is imperative [129]. Alternative application methods like lick blocks containing plant-based compounds [130] can also enhance efficiency and facilitate controlled release, allowing for prolonged usage [129].