Femoral Nerve Paralysis in Cows: Weak Quadriceps and Hindlimb Collapse

Femoral nerve paralysis is a loss of normal function in the femoral nerve, the nerve that helps the quadriceps muscle extend the stifle. When this nerve is injured, the cow may not be able to straighten the hind limb well enough to stand or support weight. Affected cows can look suddenly weak behind, buckle at the stifle, or become recumbent.

In cattle, hindlimb nerve injuries are often discussed alongside calving paralysis and other pelvic-limb nerve problems. Merck notes that femoral nerve injury causes inability to extend the stifle, a weak to absent patellar reflex, quadriceps atrophy, and reduced sensation on the very medial surface of the foot. That pattern helps your vet distinguish femoral nerve damage from sciatic or obturator nerve injury, which can cause different gait changes and hoof placement problems.

This is not a condition to watch at home for long. A cow that cannot rise or stand safely is at risk for pressure injury, muscle damage, poor feed and water intake, and secondary recumbency. Early veterinary assessment gives the best chance to identify whether the problem is a temporary conduction injury, a more severe nerve lesion, or another condition that only looks like nerve paralysis.

Femoral nerve paralysis happens when the femoral nerve or its nerve roots are stretched, compressed, bruised, or torn. In cattle, this may follow difficult calving, pelvic trauma, slipping injuries, prolonged recumbency, or pressure injury around the pelvis and upper hind limb. Although Merck describes calving paralysis most often affecting the sciatic and obturator nerves after excessive intrapelvic pressure from fetopelvic disproportion, the same postpartum setting can also raise concern for other pelvic-limb nerve injuries that leave a cow unable to stand normally.

Trauma is a common cause of acute monoplegia in animals. Merck explains that peripheral nerve injuries may range from neurapraxia, which is a temporary conduction problem, to axonotmesis or neurotmesis, which are more severe injuries with a more guarded outlook. The closer the injury is to the muscle it must reinnervate, the better the chance of recovery. That is one reason your vet may talk about prognosis in terms of lesion location, not only the cow's current ability to stand.

Other conditions can mimic femoral nerve paralysis and need to be ruled out. These include fractures of the femur or pelvis, hip luxation, severe quadriceps or adductor muscle injury, spinal cord disease, metabolic causes of recumbency such as hypocalcemia, and combined nerve injuries involving the sciatic or obturator nerves. In fresh cows, more than one problem may be present at the same time.

Diagnosis starts with a careful history and a full physical and neurologic exam. Your vet will ask whether the weakness began after calving, trauma, slipping, prolonged time down, or difficult handling. On exam, they will watch posture and gait if the cow can stand, then assess the stifle, patellar reflex, pain perception, muscle tone, and areas of skin sensation. Merck notes that femoral nerve lesions cause inability to extend the stifle, a weak to absent patellar reflex, quadriceps atrophy, and sensory loss on the very medial surface of the foot.

Your vet will also work to localize the lesion and separate femoral nerve paralysis from sciatic, obturator, or spinal disease. Merck emphasizes that evaluation of gait, spinal reflexes, superficial and deep pain perception, and muscle mass helps determine whether the lesion is in a specific peripheral nerve, the plexus, or the nerve roots. This matters because prognosis is usually better for more distal peripheral nerve injuries than for root or plexus lesions.

Additional testing depends on the case. A down cow may need bloodwork to check for metabolic disease, and some cows need imaging to look for fractures, hip injury, or severe soft tissue trauma. Electromyography can help detect denervation about 7 to 10 days after the nerve insult, but it is not always practical in field settings. In many farm cases, diagnosis is based on the pattern of deficits plus the calving or trauma history.

Not every case can be prevented, but risk can often be lowered by reducing trauma around calving and minimizing time spent recumbent. Good calving management matters. Merck links calving paralysis to excessive and prolonged intrapelvic pressure from fetopelvic disproportion, especially with difficult births. Prompt obstetric help, appropriate use of calving assistance, and timely veterinary intervention for dystocia can reduce nerve and muscle injury risk.

Housing and footing also matter. Fresh cows and injured cows need secure, non-slip surfaces and deep bedding so they are less likely to splay, fall, or struggle. If a cow goes down, early movement to a well-bedded area with good traction and frequent repositioning can help prevent secondary muscle and pressure damage. Merck specifically recommends good footing and limiting excessive hindlimb spread in calving paralysis cases to reduce further injury.

Work with your vet on herd-level prevention if you have repeated postpartum recumbency or traumatic nerve injuries. That may include reviewing sire selection and calf size risk, body condition, calving supervision, facility design, flooring, and fresh-cow monitoring. Prevention is usually a combination of safer calving, safer footing, and faster response when a cow first shows weakness.