Carvacrol is an essential oil extracted from oregano which can be used as a natural additive in poultry litter and could have a positive impact not only on production rates but also on the quality of poultry meat. The aim of this study was to evaluate the effect of the addition of carvacrol to litter on weight gain and the occurrence of residues in chicken tissues.

The aim of this study was to evaluate the antimicrobial activity and determine the minimum bactericidal concentration (MBC) of the essential oils derived from Origanum vulgare (oregano), Melaleuca alternifolia (tea tree), Cinnamomum cassia (cassia), and Thymus vulgaris (white thyme) against Salmonella Typhimurium, Salmonella Enteritidis, Escherichia coli, Staphylococcus aureus and Enterococcus faecalis. The study also investigated the ability of these different bacterial strains to develop adaptation after repetitive exposure to sub-lethal concentrations of these essential oils. The MBC of the essential oils studied was determined by disc diffusion and broth dilution methods. All essential oils showed antimicrobial effect against all bacterial strains. In general, the development of adaptation varied according to the bacterial strain and the essential oil (tea tree > white thyme > oregano). Therefore, it is important to use essential oils at efficient bactericidal doses in animal feed, food, and sanitizers, since bacteria can rapidly develop adaptation when exposed to sub-lethal concentrations of these oils.

This study examined the therapeutic effects of aromatherapy for the treatment of otitis externa in dogs. Eleven dogs with otitis externa were examined. The control group (5 dogs) was treated with susceptible antibiotics, and the experimental group (6 dogs) was treated with aroma-oil applied topically to the ear canal. The aroma-oil contained 10 ml sweet almond oil, 0.3 ml bergamot oil, 0.2 ml lavender oil, 0.1 ml tea tree oil and 0.1 ml roman chamomile oil. The blended aroma-oil (0.1 ml) was applied to the ear canal twice daily for 2 weeks. The authors examined the changes in the clinical signs, bacterial count in discharges, total WBC count and neutrophil/lymphocyte ratios in the two groups. The bacterial cell counts in the experimental group were significantly lower at one (p less than 0.01) and two weeks (p less than 0.05) after treatment than the control group. These results suggest that aromatherapy is an effective and practical treatment for otitis externa in dogs.

Objective—To evaluate the effectiveness of a topically applied gel containing essential oils (menthol and thymol) and polyphenolic antioxidants (phloretin and ferulic acid) for reducing halitosis in dogs. Animals—20 dogs. Procedures—A blinded crossover clinical trial was conducted. Dogs received a dental cleaning and examination (periodontal examination including periodontal probing and assessments of plaque, calculus, and gingivitis). Owners then applied a gel (active or placebo) to oral soft tissues twice daily for a 4-week period. Teeth of the dogs were cleaned again, and owners applied the other gel for a 4-week period. Clinicians scored halitosis immediately after the initial cleaning and at 4 and 8 weeks, and owners scored halitosis weekly. Results—Halitosis assessment by clinicians revealed that both groups had improvement in halitosis scores. Two dogs were removed because of owner noncompliance. In the active-to-placebo group (n = 9), halitosis was significantly reduced during application of the active gel but increased during application of the placebo. Seven of 9 owners reported increased halitosis when treatment was changed from the active gel to the placebo. In the placebo-to-active group (n = 9), halitosis decreased during application of the placebo and continued to decrease during application of the active gel. Seven of 9 owners reported a decrease in halitosis with the active gel. Conclusions and Clinical Relevance—An oral topically applied gel with essential oils and polyphenolic antioxidants applied daily after an initial professional dental cleaning decreased oral malodor in dogs.

In this study we examined the anti-tick properties of the essential oil of Tagetes minuta L. (Asteraceae: Asterales) against Hyalomma rufipes ticks. We obtained the essential oil of T. minuta by hydro-distillation of a combination of fresh flowers, leaves and soft stems, and analysed these by using gas chromatography (GC) and gas chromatography-linked mass spectrometry (GC-MS). The oil had a high percentage of monoterpenes and the major compounds identified were cis-ocimene (28.5%), beta-ocimene (16.83%) and 3-methyl-2-(2-methyl-2-butenyl)-furan (11.94%). Hyalomma rufipes adults displayed a significant (P < 0.05) dose repellent response to the essential oil of T. minuta. Probit analysis indicated a repellent EC50 of T. minuta essential oil for male ticks to be 0.072 mL/mL (CI 0.053 mL/mL to 0.086 mL/mL) and 0.070 mL/mL (CI 0.052 mL/mL to 0.084 mL/mL) for female ticks. There were no significant differences in repellent responses between male and female ticks. The oil also significantly (P < 0.05) delayed moulting of 60% of H. rufipes engorged nymphs. These results suggest that T. minuta may be a potential source of anti-tick agents.

Objective: The objective of this study was to determine the comparative larvicidal efficacy of com¬mercial ylang-ylang (Cananga odorata) essential oils from India and Thailand against the Aedes aegypti mosquito to be used as a guideline for Aedes mosquito control. Materials and Methods: The bioassay for the larvicidal activity of commercial ylang-ylang essen¬tial oils in this experiment was modified from the World Health Organization standard protocols. The concentration ranges at 0.025, 0.050, 0.075, 0.100, 0.125, and 0.150 ppm in each treatment were used for testing, and four replicates were used per concentration. The larval mortality was observed and recorded 24- and 48-h after exposure. Results: The results of this study clearly revealed that commercial ylang-ylang essential oils from India and Thailand were highly toxic to the larvae of the dengue vector Ae. aegypti, and Indian ylang-ylang had an LC50 value of 0.064 ppm, whereas Thai ylang-ylang had an LC50 value of 0.042 ppm after 24-h exposure. Conclusion: This study revealed the efficacy of commercial Indian and Thai ylang-ylang essential oils as natural vector control for the larval stage of the dengue vector Ae. aegypti. Usually, natural larvicide products are not commonly found in the market due to complex production processes. The results of this research support the use of commercial essential oils to aid in further control of Aedes mosquito larvae populations in the community. [J Adv Vet Anim Res 2020; 7(3.000): 391-396]