Spastic paresis is a progressive neuromuscular disorder that causes spastic contraction of the gastrocnemius or quadriceps, resulting in hyperextension of one or both hind limbs. It occurs sporadically in most breeds of cattle. Post-legged cattle are most frequently affected. Attempts to move are believed to simultaneously trigger contractions of both extensors and flexors of the limb. Spastic paresis has long been considered to be inherited via a recessive gene or genes with incomplete penetrance, although the etiology has not been conclusively elucidated. Although the condition appears in many beef and dairy breeds, in Holstein calves, spastic paresis is also known as Elso heel in reference to a possible genealogical link to a popular sire: a Friesian bull named Elso II.
Clinical Findings of Spastic Paresis in Cattle
Spastic paresis may develop within the first 6 months of life. As the animal ages, the gastrocnemius muscles gradually contract. The hock and stifle joints become increasingly extended. Over a period of months, the hind limbs become so stiff that the animal walks with short, pendulum-like steps. If only one limb is affected, the animal stands with the affected limb camped back and the unaffected contralateral limb held toward the midline to maintain balance. If both hind limbs are affected, the animal may attempt to bear more weight on the forelimbs by holding them well back and simultaneously arching its back.
The quadriceps muscle has been implicated in the pathology of spastic paresis and can be distinguished from the form of the disorder affecting the gastrocnemius through administration of a femoral nerve block or lumbosacral epidural with procaine or lidocaine. The clinical signs are thought to be primarily caused by an overactive stretch reflex that appears to be associated with defective glycinergic synaptic transmission in the accompanying spinal cord segment.
Treatment of Spastic Paresis in Cattle
There is no successful medical treatment for spastic paresis. Because the disorder is heritable, affected animals (especially breeding bulls) should be eliminated from the herd. Palliative surgical treatment may be attempted, although ethical issues should be considered when breeding stock is involved. The procedures, usually performed on calves, include the following: complete tibial neurectomy, which results in sufficient relief to permit a steer to be finished for slaughter; complete tenotomy of the gastrocnemius tendon, which results in a dropped hock; and partial tenectomy of the two insertions of the gastrocnemius muscle and the calcanean tendon sheath, which overcomes the problem of the dropped hock. Of these treatments, tibial neurectomy provides the most satisfactory results because it retains the normal anatomy while addressing the specific response to an overactive stretch reflex.
For More Information
de Lahunta A, Divers TJ. Chapter 13: Neurologic Diseases. In: Divers TJ, Peek SF. Rebhun's Diseases of Dairy Cattle. 3rd ed. Philadelphia: Saunders Elsevier, 2018;605–667.
Lorenz MD, Coates JR, Kent M. Handbook of Veterinary Neurology. 5th ed. St Louis: Saunders/Elsevier; 2011.