Diarrhea in Newborn Lambs: Causes, Field Epidemiology in Iraq, and Scientific Critique of Antibiotic Use

Dr. Nahlan Juwair Hassan / Poultry and Animal Diseases Specialist / Samarra – Iraq

29-3-2026

Abstract

Diarrhea in newborn lambs is one of the most important diseases with a significant economic impact on sheep farming, as it is associated with high mortality rates and reduced productivity (Radostits et al., 2007). The disease is complex, multifaceted, and multifactorial, primarily involving infectious agents such as Escherichia coli bacteria, enteroviruses such as Rotavirus and Coronavirus, and some parasites such as Cryptosporidium spp. (Merck Veterinary Manual, 2023; Constable et al., 2017). In addition to non-infectious factors, primarily poor colostrum feeding management and adverse environmental conditions (grounding, temperature, mixing, etc.), cases in Iraq generally appear as field outbreaks within enclosed barns, with the widespread and irrational use of antibiotics, particularly enrofloxacin. This review aims to examine the causative agents and field epidemiology, critically assess antibiotic use, and emphasize supportive and preventative treatment.

1- Introduction

Neonatal lamb diarrhea is one of the most common health problems in sheep flocks during the first few weeks of life (Smith & Sherman, 2009). The disease is characterized by its multiple causes and the interplay of infectious, environmental, and management factors, making it a classic example of a multifactorial disease (Constable et al., 2017). The disease leads to significant economic losses due to mortality, reduced growth, increased treatment costs, and lost season.

2- Pathogens and Pathogenic Mechanisms

The main infectious agents include:

• Escherichia coli (Enterotoxigenic strains)
• Rotavirus and Coronavirus (viral enteritis)
• Cryptosporidium parvum

These agents (pathogens) lead to the destruction of the intestinal epithelial cells (lining), causing malabsorption and impaired secretion of fluids within the intestinal lumen and resulting in severe diarrhea (Radostits et al., 2007). In severe cases, the primary cause of death is indirect (dehydration and metabolic acidosis) rather than the direct effect of the pathogen (Constable et al., 2017).

Non-infectious factors also play a significant role, including:

• Insufficient or delayed colostrum intake, which contains maternal antibodies that protect the newborn during the first period of life (failure of passive transfer) (Smith & Sherman, 2009).
• Maternal malnutrition, which directly affects fetal health and immunity.
• Overcrowding and poor ventilation, which cause the spread of diseases within the herd and directly impact newborn births.
• Contaminated birthing environment, including contaminated bedding and flooring, which may harbor pathogens that are easily transmitted to the newborn through the mouth, placenta, or respiration.

3- Clinical and Epidemiological Characteristics:

The infection manifests as watery or yellowish diarrhea, severe dehydration, general weakness, and a decrease in grazing behavior and feeding. Epidemiologically, cases often occur as outbreaks among newborns within the herd, indicating a stressful environmental factor and poor management (Merck Veterinary Manual, 2023).

4- Field Epidemiology in Iraq

Across all regions of Iraq, neonatal diarrhea is one of the most common diseases in traditional and semi-intensive poultry farming systems, and it may be more severe during the winter calving season. Field observations indicate that the disease is more closely related to housing conditions and management (handling of calving) than to being a random disease (FAO, 2021). Key field factors include:

• Poorly ventilated, enclosed barns (hypertrophic conditions).
• High humidity and manure accumulation (stress factors and irritants to the respiratory system).
• Poor hygiene in calving areas (easily transmits diseases through direct contact). • Delayed or insufficient colostrum administration (weakened maternal immunity and reduced ability to fight off pathogens).
• Overcrowding and mixed ages (a stress factor that facilitates disease transmission).

Field reports and local research indicate that the most common pathogens are E. coli, Cryptosporidium parvum, and enteroviruses, and infections are often mixed (Constable et al., 2017; Merck Veterinary Manual, 2023).

5. Scientific Critique of Antibiotic Use in the Field

5.1 Common Use: In many farms in Iraq, the antibiotic enrofloxacin is widely used as a first-line treatment for diarrhea without proper laboratory diagnosis (FAO, 2021).

5.2 Lack of Scientific Justification: Diarrhea does not necessarily have to be caused by a pathogen sensitive to enrofloxacin. Evidence suggests that a significant proportion of diarrhea cases are due to pathogens that do not respond to antibiotics, such as:

• Viral pathogens (Merck Veterinary Manual, 2023)
• Parasitic pathogens such as Cryptosporidium
• Management and dietary factors

5.3 Pharmacological Limitations of Enrofloxacin Use

• Inconsistent absorption from the intestines of newborns after oral administration.
• Negative interaction with milk and colostrum.
• Potential for reaching subtherapeutic concentrations. • Increased risk of antibiotic resistance (WHO, 2020)

5.4 Antibiotic resistance: Irrational use of fluoroquinolones leads to the emergence of resistant strains of E. coli and reduces the effectiveness of future treatment (WHO, 2020).

5.5 Treatment recommendations: Treatment should primarily consist of:

• Fluid replacement and electrolyte correction (Constable et al., 2017)
• Correction of metabolic acidosis
• Keeping the infant warm
• Supporting colostrum intake
• Antibiotics should only be used in cases of confirmed or suspected septicemia.

6- Prevention and Control

Disease control depends on the following factors:

• Administering colostrum within the first 2–6 hours after birth (Smith & Sherman, 2009)
• Improving hygiene in lambing pens
• Reducing overcrowding
• Improving ventilation
• Isolating infected lambs
• Focusing on supportive care

7- Conclusion

Diarrhea in newborn lambs is a multifactorial disease that depends heavily on the success of field management. In Iraq, environmental conditions, coupled with poor colostrum management, play a pivotal role in increasing infection rates. The routine use of antibiotics, particularly enrofloxacin, which is not based on strong scientific evidence in most cases, may contribute to antibiotic resistance without improving treatment outcomes. Therefore, strategies should be redirected towards prevention and supportive treatment.

references :

• Radostits, O.M. et al. (2007). Veterinary Medicine.

• Constable, P.D. et al. (2017). Veterinary Medicine: A textbook of the diseases of cattle, sheep, goats.

• Smith, M.C. & Sherman, D.M. (2009). Goat Medicine.

• Merck Veterinary Manual (2023). Neonatal diarrhea in ruminants.

• FAO (2021). Small Ruminant Health Management Reports.

• WHO (2020). Antimicrobial resistance and veterinary use guidelines.