Respiratory diseases constitute one of the major challenges to poultry production in the Middle East, resulting in substantial economic losses due to increased mortality, reduced growth performance, poor feed conversion and higher costs of medication and control.

The epidemiology of respiratory diseases in the region is complex and influenced by infectious agents, climatic conditions, production systems and varying levels of biosecurity:

• Infectious Bronchitis: remains among the most prevalent viral respiratory diseases affecting poultry. Outbreaks are reported mainly during the winter season, when low ambient temperatures, increased humidity, and inadequate ventilation favor virus survival and transmission. The continuous emergence of new IB variant strains compromise vaccine efficacy, leading to clinical disease even in vaccinated flocks.
• Avian Influenza: continues to represent a serious and ongoing threat to poultry production in the Middle East. Outbreaks may occur during different seasons and increase during spring and autumn, coinciding with the migration of wild birds along migratory pathways. Those wild birds act as natural reservoirs of influenza A viruses, and their seasonal movement facilitates the introduction of new virus strains into domestic poultry populations, particularly in open housing systems with insufficient biosecurity measures.
• Newcastle Disease: is endemic in many Middle Eastern countries and characterized by recurrent outbreaks throughout the year. These outbreaks are commonly associated with immunity gaps, improper vaccination schedules, poor vaccine handling, or inadequate application techniques. Symptoms might be respiratory, nervous or digestive disorders with very high mortalities when infections involve virulent strains such as genotype VII.
• Mycoplasma infections: mainly Mycoplasma gallisepticum and Mycoplasma synoviae, play a significant role in chronic respiratory disease complexes. Both vertical transmission from breeder flocks and horizontal transmission between farms are frequently observed. Co-infection with viral pathogens such as IB, ND, or AI markedly aggravates clinical signs and production losses, especially under stressful environmental conditions.
• Escherichia Coli: respiratory pathogens like IBV, Mycoplasma and NDV or stressors (poor ventilation, high ammonia), cause mucous damage and predispose respiratory tract to APEC invasion causing severe fibrinous inflammations.

In addition to vaccination, biosecurity and antimicrobial therapy when indicated, the use of respiratory enhancers represents an important supportive strategy in the management of respiratory diseases. These products do not replace vaccines or treatments but help alleviate clinical signs, improve respiratory function, and support the immune response during periods of high respiratory challenge.

Respiratory enhancers based on essential oils have become a trusted solution among farmers and veterinarians due to their natural origin, fast-acting effect, and ease of administration. Delivered through drinking water, these combinations ensure uniform intake across the flock and act quickly at the respiratory tract level, providing immediate relief and support.

Beyond their convenience, these products combine multiple functional components that work synergistically to improve breathing and overall respiratory health, enhance bird comfort, and maintain performance under stress conditions. In the following part, we will explore the three key components that drive these benefits, each playing a distinct role in optimizing respiratory function and overall flock wellbeing:

1. Menthol: Beyond its decongestant and cooling properties, menthol has been shown to significantly improve broiler performance. Studies report that menthol supplementation for broilers increases body weight and daily gain by up to 18%, enhances feed intake, and improves feed conversion ratio (FCR) (Abdel-Wareth et al., 2019). These benefits are attributed to menthol’s ability to support immune function, ease breathing, and reduce oxidative stress. Additionally, menthol’s activation of TRPM8 receptors exhibits cooling effects that help birds cope with stress and respiratory discomfort, further promoting feed and water intake under challenging conditions (Bernard et al., 2025).
2. Thymol: Thymol is widely recognized for its multifunctional properties in poultry health. Beyond its antimicrobial and antioxidant activities, thymol acts as a potent respiratory enhancer, functioning primarily as an expectorant. It promotes mucus liquefaction and clearance from the trachea and bronchi, thereby improving airway patency and facilitating efficient oxygen exchange, critical under respiratory stress conditions. In addition to these benefits, thymol influences growth performance and feed utilization. Some trials summarized by Majid et al. (2022) indicate that thymol can deliver measurable improvements in growth performance when used at optimized doses or in synergistic blends with other phytogenic compounds. Additional benefits include increased body weight gain, improved feed intake, and enhanced feed conversion ratio (FCR). These positive outcomes are attributed to thymol’s ability to enhance digestive enzyme activity, modulate gut microbiota, and exert antioxidant and anti-inflammatory effects, which contribute to nutrient absorption and metabolic efficiency (Majid et al., 2022).
3. Eucalyptol: Eucalyptol offers immune-supporting and mild antimicrobial properties, enhancing local respiratory defense mechanisms, stimulating macrophage activity, and contributing to improved air quality within poultry houses. Its immunomodulatory effects are linked to the suppression of pro-inflammatory cytokines and the upregulation of anti-inflammatory mediators, while its antimicrobial activity helps maintain respiratory health by reducing pathogen load. Eucalyptol supplementation has been shown to improve broiler growth performance significantly. Research indicates that adding 20 – 30 mg/kg of eucalyptol increases average daily gain (ADG) and reduces feed conversion ratio (FCR). These improvements are attributed to enhanced intestinal morphology and overall health status, making eucalyptol a promising phytogenic additive for boosting productivity and supporting overall flock resilience under stress conditions (Di et al., 2022).

In brief, respiratory diseases in the Middle East poultry sector are multifactorial and dynamic. Effective prevention and control rely on integrated strategies that combine proper vaccination programs, strict biosecurity, proper housing and ventilation, continuous surveillance, and supportive measures such as respiratory enhancers. The strategic use of essential oil based respiratory enhancers containing thymol, menthol, and eucalyptol like UtriRespi, can alleviate clinical severity, improve flock comfort, and support recovery, particularly during high-risk periods.