The question of whether cows cry tears is best answered by separating the biological function from the emotional experience. Cows absolutely produce tears as a normal physiological function, necessary for maintaining eye health, just like all mammals. However, they do not produce the specific type of tears linked to complex emotions like sadness or grief, which is widely considered a unique characteristic of human psychology. When a cow appears to be crying, it is almost always a physical reaction to irritation or illness, not an outward sign of emotional distress.
The Biological Purpose of Tears
All land mammals, including cattle, possess a lacrimal system that continuously secretes a fluid to protect the eye’s surface. These tears form a three-layered film over the eye for lubrication and clear vision. The outer layer is an oily substance that prevents the tear film from evaporating too quickly, while the deepest layer is composed of mucins that anchor the tear film to the cornea.
The middle layer, the thickest, is an aqueous solution containing proteins and electrolytes. This layer supplies the cornea with necessary nutrients and oxygen, and provides a washing action to remove small debris. Tears contain antimicrobial agents, such as lysozyme, which help the eye defend against invading pathogens and infections.
Understanding Emotional Crying
Tears are generally categorized into three types: basal (for constant maintenance), reflex (in response to irritants), and psychic or emotional tears. While cows produce basal and reflex tears, scientific evidence does not support the existence of psychic tears in cattle. The production of emotional tears in humans is thought to be tied to complex social signaling and specific brain structures that trigger the lacrimal glands in response to strong feelings.
This does not mean that cows are devoid of feeling; they are sentient animals that experience a wide range of emotions, including fear, anxiety, and distress. When a cow is distressed, such as during separation from a calf, they express this through behavioral changes like increased vocalizations and altered posture, not through lacrimal overflow.
Causes of Excessive Tearing in Cows
When a cow exhibits excessive tearing, medically known as epiphora, it signals a problem with the eye’s physical environment or health. One common cause is a reaction to environmental irritants, such as ammonia fumes in barn air, dust, pollen, or strong winds. These irritants stimulate the lacrimal glands to produce a flood of reflex tears as the eye attempts to flush out the offending material.
The overflow can also be caused by blockages in the nasolacrimal duct, the drainage pathway that carries tears from the eye into the nasal cavity. If this duct is obstructed by inflammation, a foreign body like a grass seed, or a congenital issue, the tears simply spill out onto the face instead of draining internally.
Excessive tearing is also a primary clinical sign of several common eye diseases in cattle. Infectious Bovine Keratoconjunctivitis (Pinkeye) is a bacterial infection that causes irritation, pain, and a profuse, watery discharge that can progress to a thick, cloudy secretion. Other conditions, such as Infectious Bovine Rhinotracheitis (IBR) or the presence of eye worms, can trigger this same watery discharge as the body attempts to fight off the infection or flush out the parasite.