Sheep sometimes exhibit behavior that involves hitting their heads, ranging from natural social interaction to a grave sign of neurological distress. This action may involve rapid, forceful impact against another animal or slow, persistent pressure against an inanimate object. Understanding the context of this behavior is crucial to determine its severity. Observing who is performing the action, against what, and if any other symptoms are present is the most important first step in assessing the situation.
Head-Butting as Normal Social Behavior
The most common form of sheep hitting their heads is head-butting, a fundamental part of establishing and maintaining the flock’s social structure. This forceful behavior is typically directed toward other sheep, often involving a charging motion before the impact. Head-butting serves as a non-fatal method for animals to resolve disputes over resources or social standing, creating a stable dominance hierarchy within the group.
Rams engage in the most dramatic head-butting, particularly during the rutting season when they compete for breeding rights. These contests involve two rams backing away from each other and then charging to meet head-to-head with a loud impact. This ritualistic fighting establishes which males are strongest and most dominant, ensuring the breeding season proceeds with minimal conflict.
Young lambs also engage in head-butting as a form of play behavior, testing their strength and coordination in preparation for later life. This playful sparring is generally less intense than the clashes between mature rams and helps the lambs develop motor skills and integrate into the social order. Ewes, or female sheep, also use head-butting and shoulder-pushing to communicate or maintain their position in the hierarchy.
Head-Pressing and Neurological Concerns
Head-pressing is a concerning behavior distinct from social head-butting. The animal pushes its forehead continuously against a fixed object, such as a wall, fence, or corner. This action is a classic sign of neurological dysfunction, indicating inflammation or pressure within the brain. Two common causes of this abnormal behavior are the infectious disease Listeriosis and the nutritional disorder Polioencephalomalacia (PEM).
Listeriosis, or “circling disease,” is caused by the bacterium Listeria monocytogenes, often introduced through consuming spoiled silage. The bacteria ascend a cranial nerve, localizing the infection to one side of the brainstem and causing unilateral nerve deficits. Affected sheep may show a characteristic head tilt, a drooping ear, and paralysis of the lip on one side of the face. They often propel themselves into corners because they are disoriented.
Polioencephalomalacia (PEM), also known as cerebrocortical necrosis (CCN), results from a thiamine (Vitamin B1) deficiency or high sulfur intake. This condition destroys neurons in the cerebral cortex, leading to clinical signs like blindness, “star-gazing” (head pulled back), and the compulsion to press the head against objects. While both Listeriosis and PEM cause head-pressing, PEM-affected sheep are often blind and may arch their heads backward.
Environmental and Nutritional Causes of Abnormal Head Behavior
Several non-infectious environmental and nutritional factors can disrupt brain function and trigger abnormal head behavior. These causes primarily involve the ingestion of toxins or a lack of specific micronutrients. Heavy metal toxicity, such as lead poisoning from ingesting discarded batteries or contaminated materials, is a concern.
Lead poisoning often results in central nervous system signs, including blindness, incoordination, and the characteristic head-pressing behavior. This toxic accumulation causes swelling and damage to the brain’s cerebral cortex, leading to altered mental status and the compulsion to push against fixed points.
Cobalt Deficiency
A severe deficiency of Cobalt, which is necessary for the synthesis of Vitamin B12 in the rumen, can lead to nervous signs in lambs known as “ovine white liver syndrome.” Affected young animals may display depression, aimless wandering, or head pressing against objects due to the resulting liver and brain damage.
Vitamin A Deficiency
A lack of Vitamin A can also cause neurological deficits, including night blindness, an unsteady gait, and convulsions. This highlights the brain’s sensitivity to diet and micronutrient levels.
When Head Behavior Requires Veterinary Intervention
Differentiating between normal social head-butting and pathological head-pressing is necessary for determining when to seek professional help. If the behavior is a rapid, aggressive interaction directed toward another animal, it is likely a normal social display. However, any behavior involving sustained pressure against a fixed object, or a sudden change in head posture, requires immediate veterinary consultation.
Secondary symptoms accompanying the head behavior are the most reliable warning signs of a severe underlying disease. These include systemic signs like fever, lack of appetite, and isolation from the rest of the flock. Neurological signs such as circling, an unsteady gait (ataxia), blindness, or facial paralysis indicate a brain or brainstem lesion. Prompt treatment, such as antibiotics for Listeriosis or thiamine injections for PEM, can significantly increase the chances of recovery if administered early in the disease progression.