This condition is most common in cats with arterial thromboembolism secondary to myocardial disease. It also is seen in dogs with a variety of underlying disorders including hyperadrenocorticism, hypothyroidism, renal disease, cancer, and heart disease. Occlusion occurs most commonly at the distal aortic trifurcation, resulting in ischemia of muscles and nerves in the pelvic limbs. There is acute, painful paraparesis and an inability to flex or extend the hock. The flexor reflex and, in some cases, the patellar reflex are lost. Sensation distal to the hock is decreased. The gastrocnemius and cranial tibial muscles are often firm and painful. The nails may be cyanotic, and the femoral pulses are weak or absent.
Diagnosis can usually be made based on clinical features. Serum CK is often elevated. Doppler ultrasonography is useful in evaluating blood flow in the distal aorta and femoral arteries. Pathologic changes are present distal to the level of the middle to lower thigh and are characterized as focal muscle necrosis and degeneration of the central portions of the sciatic nerve and its branches. Management consists of diagnosis and treatment of any underlying disease (eg, cardiomyopathy) and anticoagulant or antiplatelet-aggregating drugs. Neurologic deficits may improve within 2–3 wk, but 6 mo may be required for complete recovery. Permanent deficits are possible. The longterm prognosis is guarded because of the underlying heart disease and high risk for recurrence of thrombo-embolism.
Last full review/revision July 2011 by William B. Thomas, DVM, MS, DACVIM (Neurology)