Spastic paresis

What it is

Bovine spastic paresis (Elso heel) is a sporadic, progressive neuromuscular disease in which one or more muscles of the pelvic limb have increased tone or permanent spasm. In the classic form the gastrocnemius muscle is affected, often together with the superficial digital flexor, and the tarsus (hock) is held in hyperextension. A quadriceps femoris form, which extends the stifle, and a mixed form are also described. Its cause is unknown; a disturbance in the nervous control of the stretch reflex is suspected, without obvious structural lesions in the muscle.

Although it is classified as a congenital disease and is usually attributed to inheritance, signs appear after birth and the genetic basis has not been demonstrated (see Key studies). It should not be confused with bovine spastic syndrome (crampy) of adults, which causes episodes of spasm of both pelvic limbs when the animal rises.

Who it affects

Calves of beef and dairy breeds; it has been described in many breeds, with frequent cases in Holstein and Belgian Blue. Signs usually appear between the first weeks and the first months of life and progress gradually. One or both pelvic limbs may be affected.

Anatomy involved

• Gastrocnemius muscle: its lateral and medial heads arise from the caudal aspect of the distal femur and insert, through the common calcaneal tendon, on the calcaneal tuber. Its contraction extends the tarsus; in this disease the muscle is tense and hard on palpation.
• Superficial digital flexor muscle of the pelvic limb: it arises from the supracondylar fossa of the femur, its tendon winds around that of the gastrocnemius, forms a cap over the calcaneal tuber and continues to the digits. It takes part in the spasm in many animals. Both muscles are innervated by the tibial nerve, which is the basis of neurectomy.
• Tarsus: the tarsocrural joint is held wide open and the hock almost straight. The calcaneus, where both muscles insert, is the lever on which the spasm acts.

Clinical signs

The affected limb is held stiff and extended backwards, with the hock wide open and sometimes only the tip of the claw touching the ground. When walking, the animal swings the limb back and forth like a pendulum, barely bears weight on it and is lame. Signs are seen when standing and moving, and disappear when the animal lies down. Over time the spasm intensifies, the animal grows less well and loses condition. In the quadriceps form the stifle is held extended; in the mixed form both patterns combine.

Diagnosis

• Clinical: the typical posture with the hock in hyperextension, tension in the gastrocnemius and calcaneal tendon, and disappearance of signs at rest.
• Identifying which muscles are involved (gastrocnemius, quadriceps or both) is key to choosing treatment; anaesthetic blocks of the nerves involved can help.
• Differential diagnosis: upward fixation of the patella, lesions of the tarsus or stifle, hip luxation, spinal cord lesions and the spastic syndrome of adults.

Treatment

• Partial tibial neurectomy: section of the branches of the tibial nerve that supply the gastrocnemius and, depending on the case, the superficial digital flexor; the most widely used treatment for the gastrocnemius form.
• Tenotomy or tenectomy of the gastrocnemius tendon (with or without the superficial digital flexor), as an alternative; it can cause excessive flexion of the hock.
• The quadriceps form has no effective surgical treatment, and in the mixed form surgery only partially improves the animal.
• Without treatment the disease progresses; many animals are fattened and slaughtered early.
• Traditionally, affected animals are not used for breeding, although heritability is unproven.
• Anaesthetics and analgesics used in surgery are subject to national regulations and to withdrawal periods for meat and milk.

Key studies

There are no controlled trials on this disease; the available evidence consists of narrative reviews and retrospective series without a control group.

• De Vlamynck et al. (2014), narrative review, the current reference. It describes the gastrocnemius, quadriceps and mixed forms, notes that in some breeds the atypical forms appear to be increasing, that distinguishing them is difficult and that surgical treatments usually fail in the atypical forms.
• Goeckmann et al. (2016), narrative review of the genetic background. It concludes that there is no definitive proof that spastic paresis is inherited, even though this has been assumed since its first description in 1922, and that known allele frequencies and the incidence of proven hereditary diseases in cattle contradict that assumption.
• De Vlamynck et al. (2016), retrospective series of 79 calves with long-term telephone follow-up: 26 with the gastrocnemius form (33%), 16 with the quadriceps form (20%) and 37 mixed (47%). Of 26 calves with the gastrocnemius form, 25 underwent partial tibial neurectomy and 86% recovered completely. In the mixed form, 81.5% of the 29 operated calves improved but none recovered fully, and all unoperated calves worsened. No calf with the quadriceps form was operated on; 66.7% worsened and 33.3% improved spontaneously.
• Vlaminck et al. (2000), series of 113 Belgian Blue calves (52 unilaterally and 61 bilaterally affected) treated by partial tibial neurectomy and followed by telephone for at least 3.5 months. The result was good in 83.2%; 4.4% improved considerably but still had intermittent spasms, 4.4% developed severe hyperflexion of the hock requiring early slaughter and 8% showed little or no improvement. It is an uncontrolled series in a single breed.