Chad ( Figure 1 ) is a landlocked country located between the 7th and 14th degrees of north latitude and the 13th and 24th degrees of east longitude. Serving as a bridge between the Maghreb and Central Africa, the country spans an area of 1,284,000 km², making it the fifth largest nation in Africa. Chad shares borders with Sudan to the east, Cameroon, Niger, and Nigeria to the west, Libya to the north, and the Central African Republic to the south.

Administratively, Chad is divided into 23 provinces, 107 departments, and 377 municipalities, with a total population of 17 million inhabitants, corresponding to a population density of 12 inhabitants per square kilometre [8] .

Chad is a Sahelian country with an agropastoral vocation, and its economy relies heavily on agriculture and livestock farming. Livestock farming plays a crucial role in poverty reduction and serves as a key instrument for enhancing food security.

Indeed, the socio-economic importance of the livestock subsector is indisputable, with a national herd of 94 million animals of all species combined. The subsector sustains approximately 40% of the rural population, accounts for 53% of the rural sector’s GDP, and provides employment to 80% of the active population [9] .

Study Framework

The study was conducted in poultry farms located in N’Djamena, the capital of Chad, which lies within the Sahelian zone and is characterised by an agro-pastoral orientation. Although geographically peripheral, N’Djamena is the main communication hub of the country and has experienced rapid population growth since the early 1980s. With an average annual growth rate of 7 percent, the population was estimated at over 1,700,000 inhabitants in 2022, representing nearly 10 percent of the country’s total population [8] .

Field activities began with several surveys conducted in veterinary services, followed by consultation of archives, to gain an understanding of the overall situation regarding antibiotic use in livestock within the study area. These surveys involved key institutions such as the Sub-directorate of Hygiene and Public Veterinary Health and the Sub-directorate of Veterinary Pharmacy, both under the National Directorate of Veterinary Services (DSV) of Chad.

The interviews were guided by a questionnaire covering the following points:

Following the interviews with officials, archives were reviewed to gather information on the main veterinary drug outlets, veterinary clinics, and poultry farms within the urban and peri-urban zones of N’Djamena.

The survey was conducted at veterinary drug outlets where veterinarians, para-veterinarians, and poultry farmers typically procure their medications. The aim was to collect data on the following:

After completing this survey, addresses of poultry farmers, veterinarians, and para-veterinarians who regularly use these outlets were recorded to identify potential participants for the next stage of the study.

This stage consisted of surveys targeting veterinarians and para-veterinarians responsible for managing poultry farm health issues. Topics included:

The survey among poultry farmers focused on:

Sampling of poultry farms was carried out using a non-probabilistic “snowball” method. Veterinary drug retailers identified volunteer veterinarians and para-veterinarians working in poultry farms, who in turn directed the survey team to poultry farms and farmers.

The study covered layer, broiler, and mixed-type poultry farms located in urban and peri-urban zones of N’Djamena. This method was chosen due to the absence of an exhaustive list of poultry farms and the reluctance of some poultry farmers to grant access to their premises. GPS was used to avoid duplication in the selection of poultry units.

Data collection followed a daily schedule covering veterinary drug outlets, veterinary clinics, and poultry farms. Upon completion, data were entered into Epi Info 7 software and then transferred to Excel and Word for organisation into tables and figures.

The survey conducted with officials from the Directorate of Veterinary Services (DSV) revealed that the distribution of veterinary medicines in Chad is handled by multiple stakeholders, including wholesale importers, veterinary pharmacies, and retailers. However, no quantitative data exist on the types and quantities of veterinary antibiotics consumed in the country, particularly those intended for poultry.

The concepts of antimicrobial resistance and antibiotic residues in animal products are well understood by the officials interviewed. A national action plan to combat antimicrobial resistance within the framework of One Health exists, as well as regulations governing the use of veterinary medicines.

However, some officials believe that these regulations are poorly enforced, thus allowing unqualified individuals to possess, distribute, and use veterinary medicines. This situation is exacerbated by the illegal importation and sale of medicines of questionable quality and origin, as well as their misuse. This phenomenon is facilitated by the porous nature of national borders.

The officials also stressed that the misuse of antibiotics in livestock farming has direct consequences for public health.

Regarding the inventory of poultry farms in the urban and peri-urban zones of N’Djamena, no precise data could be obtained. According to the officials interviewed, many farms have ceased activity over the past two years due to the ban on importing day-old chicks from Cameroon and Nigeria, the main suppliers of poultry farmers in Chad. This measure was taken following outbreaks of avian influenza in those countries. Nevertheless, a directory containing contact details of some veterinary clinic managers, veterinary drug outlets, and a few poultry farmers was retrieved through archive consultation.

During the survey conducted among the managers of veterinary drug outlets, various general pieces of information were collected and are presented in Table 1 .

It emerges from this table that the majority of the surveyed establishments are wholesale importers, representing 71% of the total, followed by veterinary pharmacies (29%). Among the seven establishments surveyed, 72% have been operating for more than 10 years in the sale of veterinary medicines. Furthermore, the presentation of a prescription is not always required for the dispensing of medications, which is contrary to the Chadian pharmacy law. This 2004 law stipulates that—any dispensing of veterinary medicines or antibiotics must be based on a prescription issued by a veterinarian and must be documented through a secured prescription. The absence of retailers in these results is explained by their refusal to participate in the survey, due to mistrust, stemming from the informal and often fraudulent nature of their activities.

The antibiotic molecules sold in the surveyed veterinary drug sales establishments were listed, and the results are presented in Table 2 .

From this table, we understand that eight (08) families of antibiotics were identified, namely macrolides, polypeptides, tetracyclines, nitrofurans, quinolones, sulfonamides, aminoglycosides, and beta-lactams. However, the variety of antibiotic families marketed varies from one establishment to another.

This result is explained by the fact that veterinary drug sales establishments in Chad source their supplies from pharmaceutical companies of their choice. These observations are similar to the findings of Soromou et al. (2022) [10] in Dubréka (Guinea) and Khalen (2013) [11] in Western Cameroon, where eight (08) families of antibiotics were also used in laying hens.

Furthermore, data on the quantity sold per antibiotic molecule were not provided by the managers of the sales establishments, citing confidentiality reasons.

Regardless of the presence or absence of diseases in the farms, poultry farmers sometimes call upon animal health professionals to ensure medical care and health monitoring of their livestock. The data corresponding to the timing of these interventions are illustrated in Figure 2 .

Veterinarians and paraveterinarians in the urban and peri-urban areas of N’Djamena are consulted in 42% of cases after the worsening of symptoms, and in 28% of cases due to therapeutic failure. In contrast, 14% of poultry farmers seek their assistance at the onset of symptoms or on a regular basis. The timing of medical intervention is crucial. A visit at the onset of clinical signs, before the animals’ condition worsens, allows the veterinarian to make a prompt diagnosis and act effectively to control not only direct losses (morbidity, mortality) and indirect losses (reduced weight gain, increased feed conversion ratio, decreased livestock population), but also the deterioration in the quality of products delivered to the consumer.

These results are lower than those reported by Henaoui and Dine (2013) [12] , who observed that 55% of poultry farmers in the Chlef region of Algeria consult veterinarians at the first signs of illness. This difference may be explained by the high level of collaboration established between poultry farmers in Chlef and their veterinarians.

The information gathered on the diagnostic methods used by veterinarians is presented in Table 3 .

Clinical examination forms the basis of diagnosis for all surveyed veterinarians and paraveterinarians. 58% combine clinical examination with necropsy to establish a diagnosis. However, none of the respondents reported using laboratory tests.

The prescription of an antibiotic treatment depends largely on the diagnostic methods used. If clinical examination alone is not always conclusive, necropsy performed on a sufficient number of subjects may provide valuable information. These data should, in principle, be supplemented with laboratory analyses (bacteriology, serology, parasitology, histology).

In avian pathology, due to the similarity of symptoms among various diseases but with different causes, clinical and/or necropsy examination alone, without laboratory testing, is not always sufficient. A correct and complete diagnostic approach must include all key principles relating to the subjects examined, including medical history, clinical, anatomopathological, epidemiological data, and laboratory analyses.

These results differ from those reported by Naimi E (2022) [13] , who observed that 53% of veterinarians in the Wilayas of Biskra, Algeria, collaborate with laboratories for diagnosing avian diseases. The lack of laboratory use by veterinarians and paraveterinarians in N’Djamena may be explained, on the one hand, by the high cost of laboratory tests, and on the other hand, by the need for rapid treatment without waiting for laboratory results, which sometimes take a considerable amount of time.

The proportion of surveyed veterinarians and paraveterinarians who resort to the use of antibiotics is shown in Figure 3 .

This figure shows that all respondents use antibiotics as part of the health management of their livestock. This result is consistent with the findings of Slatnia et al. (2008) [8] , who reported that 100% of veterinarians prescribe antibiotics for the sanitary management of their farms.

Data related to the period of antibiotic use in farms are presented in Figure 4 .

According to this figure, antibiotics are used throughout the entire farming cycle—that is, at all stages of production. This practice is now banned in some developed countries in Europe and America, where, as a precautionary measure, the use of antibiotics as growth promoters in animal feed is prohibited. These findings are consistent with those of Bodering et al. (2017) [7] , who reported that 100% of semi-industrial farms in N’Djamena were subjected to continuous application of products containing antibiotics.

The behavior of veterinarians and para-veterinarians following therapeutic failure was observed, and the results are presented in Table 4 .

Following the failure of an initial antibiotic treatment, 57% of respondents reported extending the duration of the same treatment, 28% opted for switching to a different molecule, and 14% preferred increasing the dose of the same product. None of them sought laboratory assistance or performed an antibiogram, which could contribute to the emergence or spread of antibiotic resistance in livestock farms. Similar observations following treatment failure were also reported by Soromou et al. (2022) in the municipality of Dubréka, Guinea [10] .

Information regarding the knowledge of the withdrawal period by veterinarians and para-veterinarians, as well as whether or not it is taken into account during treatments, is presented in Table 5 .

From this table, it appears that 100% of the veterinarians and para-veterinarians responsible for the health management of poultry farms are aware of the concept of withdrawal period, but do not apply it systematically. These findings are consistent with those of Soromou et al. (2022), who reported that all surveyed personnel claimed to have knowledge of the withdrawal period, but unfortunately, not all of them took it into account when prescribing antibiotics [10] .

Information regarding the knowledge of antibiotic residues among veterinarians and para-veterinarians is presented in Table 6 .

The concept of antibiotic residues in animal-derived food products is known by 71% of the respondents, while 29% are unaware of it. Regarding the consequences, 28% mentioned toxicity and diseases in humans, while 14% associated these residues with the emergence of antibiotic resistance. Although these responses lack detail, they generally reflect a certain level of awareness among veterinarians and para-veterinarians in the study area, as they are consistent with the risks associated with antibiotic residues reported in the literature, particularly by Dosso (2014) [14] and Khalen (2013) [11] . These risks include toxicity, fetotoxicity, allergic reactions, and the development of antibiotic resistance.

Information regarding the knowledge of antibiotic resistance and its consequences among veterinarians and para-veterinarians is presented in Table 7 .

The concept of antibiotic resistance is known by 85% of respondents, who identified therapeutic failure (71.42%) and reduced production (14.29%) as the main consequences. However, they consider these effects to be limited to animals, which demonstrates a partial understanding of the potential consequences of antibiotic misuse. According to Messai (2006), these effects occur on three levels.

In the survey conducted among poultry farmers, we examined the level of education of the respondents (see Table 8 ).

In terms of education, 25% of poultry farmers had a primary level of education, while 16% had received no formal education. Only 25% of respondents had attained post-secondary or university education. Thus, the educational level of poultry farmers remains relatively low, which may have a negative impact on their animal health and husbandry practices. A farmer, as a key stakeholder in poultry production, with limited education, may face difficulties in improving techniques and responding effectively to situations that could compromise the performance of their farms.

These percentages differ from those reported by Bodering et al. (2017), who investigated the use of antibiotics in poultry farming in the cities of N’Djamena and Doba, Chad. Their study revealed that 50% of poultry farmers in N’Djamena had a university-level education [7] . This difference may be attributed to policies and vocational training initiatives implemented in the sector.

In order to assess the development of poultry farming in the N’Djamena area, the flock size of each surveyed poultry farmer was determined. The results are presented in Table 9 .

It should be noted that flock sizes vary from one poultry farmer to another. These differences may be attributed to several factors, including the financial capacity of the farmers, the availability of infrastructure, the level of experience in poultry farming, and access to feed and veterinary resources.

These results differ from those reported by Khalen (2013), who conducted a study on modern poultry farms in the Western Region of Cameroon, where 51% of the surveyed farms had flock sizes ranging from 5000 to 10,000 birds [11] .

In order to determine the types of poultry production systems practiced by farmers in our study area, data were collected on the production orientation of the surveyed farms. The results are presented in Figure 5 .

Egg production is the primary activity in the surveyed farms. In contrast, these findings differ from the findings of Toe (2013) in Ivory Coast, who observed a predominance of broiler farms (68.6%) compared to layer farms (31.4%) [15] .

In order to determine the level of involvement of animal health professionals in farm health monitoring, information was collected on the presence or absence of a designated health officer for each surveyed farm. The results are presented in Figure 6 .

It should be noted that 46% of the surveyed farms have a designated health monitoring officer, while 54% do not. This situation may be explained by the preference of many farm owners to hire familiar personnel, thus excluding qualified professionals in this area.

These results are lower than those reported by Dosso (2014) who observed that 60% of farms in the Agnibilékrou district, Côte d’Ivoire, received veterinary assistance [14] . This difference may be explained by the presence of veterinary training institutions providing expertise in the field.

The survey to determine the presence or absence of a health monitoring officer on farms led us to identify the profile of the health monitoring officers in the surveyed farms (see Table 10 ).

Veterinary Para-professionals, including zootechnicians and other animal health professionals, represent the majority of health monitoring officers in the surveyed farms, with a rate of 78.57%, compared to 21.43% for veterinarians. This situation could be explained by the preference of Chadian veterinarians for working in public institutions, as well as their generally higher fees compared to other professionals.

These results are notably lower than those reported by Soromou et al. (2022), who found that 75% of the professionals working in farms in the Dubréka commune, Guinea, were veterinarians. This difference may be attributed to the presence of a veterinary school in Guinea, notably the Institute of Science and Veterinary Medicine of Dalaba, which trains qualified professionals in the field [10] .

In order to assess the level of professionalism of poultry farmers in the urban and peri-urban areas of N’Djamena, we determined the level of poultry farming training of the respondents. The results are presented in Figure 7 .

From Figure 8 , we observe that 46% of the surveyed poultry farmers have received training in poultry farming, while 54% have not received any training in this field.

This rate is higher than that reported by Biagui (2012), who noted that only 19% of the surveyed farmers had a specialization in poultry farming [16] . This difference could be explained by the growth in training provided to farmers in recent years, especially due to initiatives from development organizations and improved access to new communication technologies. Additionally, the training organized by private veterinarians also contributes to enhancing the skills of poultry farmers.

In order to identify the health issues leading to the use of antibiotics in the farms, the dominant pathologies in the surveyed farms were recorded. The results are presented in Table 11 .

The results show that coccidiosis infestation is the most common disease, affecting 58% of the visited farms. Newcastle disease (41%) ranks second in terms of prevalence, followed by colibacillosis (37%). Other diseases are also frequently observed in these farms, including Gumboro disease (25%), infectious bronchitis (20%), fowl pox (20%), and to a lesser extent, Marek’s disease and salmonellosis. These findings could explain the high use of antibiotics. These results are consistent with those reported by Niyibizi (2012), who found that the dominant diseases in the Dakar region and its surroundings were coccidiosis, Gumboro disease, and Newcastle disease for viral diseases, and colibacillosis and salmonellosis for bacterial diseases [17] .

To assess the vaccination coverage in poultry farms in N’Djamena, the diseases against which the poultry farmers vaccinate were recorded. The result is summarized in Table 12 .

Here, we note that the diseases against which poultry farmers vaccinate are viral in origin, such as Newcastle disease, Gumboro, infectious bronchitis, and fowl pox. The lack of vaccination against non-viral diseases may be explained by the fact that viral diseases are generally perceived as the most deadly in poultry farming.

To determine the causes of therapeutic failure, information was collected on those responsible for prescribing antibiotics on the farms. The result is shown in Figure 8 .

The rate of self-medication in the surveyed farms is 46%, which is lower than that reported by Soromou et al. (2022), where 70% of poultry farmers in the commune of Dubréka practiced self-medication [10] .

Information on the person responsible for administering medication in the farms is presented in Figure 9 .

Regarding the administration of medications, 8% of poultry farmers rely on the veterinarian or para-veterinarian in charge of the farm’s health monitoring. However, the majority of poultry farmers (92%) prefer to consult pharmacists and administer the products to their animals themselves. In practice, some veterinarians provide prescriptions and then leave the administration of medications to the farmers. This situation could lead to consequences such as dosage errors, improper storage practices, and inadequate preparation of medications. These findings are similar to those observed by Messai (2006), who found that 90% of farmers in the Wilayas of Algeria administered medications themselves [18] .

The results related to the use of antibiotics by poultry farmers are shown in Figure 10 .

It appears from this figure that 100% of poultry farmers use antibiotics on their farms. This result is similar to the findings of Bodering et al. (2017), who studied the use of antibiotics in poultry farming in the cities of N’Djamena, where all the surveyed farmers also used antibiotics in their farms [7] . This demonstrates their widespread use throughout the farming cycle, as well as their accessibility without the need for a veterinary prescription.

Oxytetracycline (83.33%), enrofloxacin (54.16%), and tylosin (45.83%) are the most commonly used antibiotic molecules by poultry farmers. These results align with those of Faye (2022), who indicates that tetracyclines and their combinations represent more than half (61%) of the usage in laying hen farms in the peri-urban area of Dakar [19] .

The data related to the supply of antibiotic medications is presented in Figure 11 .

The survey on the supply of antibiotics revealed that 100% of poultry farmers obtain their antibiotics from veterinary pharmacies. This can be explained by the perception that these pharmacies offer higher-quality products and provide poultry farmers with the opportunity to benefit from the advice of pharmacists. These results are similar to those of Bodering et al. (2017) [7] , who also found that 100% of farmers in semi-industrial poultry farms sourced their antibiotics from pharmacies.

Information regarding the poultry farmers’ attitude in case of therapeutic failure was collected and is presented in Figure 12 .

The investigation into poultry farmers’ attitudes toward therapeutic failure revealed that, in most cases (37.5%), farmers prefer to extend the duration of the same medication or administer another antibiotic. These results are similar to those of Soromou et al. (2022) [10] , where 33% of poultry farmers in the urban commune of Dubréka extended the treatment without resorting to an antibiogram in the case of therapeutic failure.

According to the table, it appears that 100% of poultry farmers administer antibiotics orally by mixing them with the drinking water, preparing the necessary amount of water for daily treatment. These results are comparable to those obtained by Zerbo (2014) and Khalen (2013) in poultry farms in Ouagadougou (Burkina Faso) and western Cameroon, where, in all the farms visited, the oral method is systematically used to administer medications by adding them to the drinking water [11] [20] .

The information on the administration of antibiotics to chickens in the finishing or laying phase is presented in Table 15 .

It appears from the table that 100% of poultry farmers administer antibiotics to chickens in the finishing phase and to laying hens. This practice can be explained by the recognized effectiveness of antibiotics in treating various diseases in farms. Additionally, the farmers’ lack of awareness regarding withdrawal periods, antibiotic residues, and antibiotic resistance contributes to this attitude. These results are similar to those reported by Dosso S. (2014), who observed that 100% of the farms surveyed did not consider withdrawal periods [14] .