Vascular disorders of the peripheral nerves in animals encompass diseases in which the blood supply to peripheral nerves is disrupted or compromised, causing damage to nerve tissue, which can occur with ischemia, vasculitis, infections, and hypercoagulable states. The most common vascular disease affecting the peripheral nerves in animals is ischemic neuromyopathy associated with aortic thromboembolism.
Ischemic Neuromyopathy
Ischemic neuromyopathy is most common in cats that have arterial thromboembolism secondary to myocardial disease. It also occurs in dogs with a variety of underlying disorders, including hyperadrenocorticism (pituitary-dependent, adrenal-dependent, or iatrogenic), hypothyroidism, renal disease, cancer, and heart disease. Occlusion occurs most often at the distal aortic trifurcation, resulting in ischemia of muscles and nerves in the pelvic limbs.
Clinical signs of ischemic neuromyopathy include the following:
acute, painful paraparesis
an inability to flex or extend the hock (tarsus)
loss of the flexor reflex and, in some cases, the patellar reflex
decreased sensation distal to the hock
firm and painful gastrocnemius and cranial tibial muscles
cyanotic nails
weak or absent femoral pulses
Diagnosis of ischemic neuromyopathy is usually based on clinical signs. Serum creatinine concentration and serum CK activity are often increased. Blood glucose concentrations might vary substantially between affected and unaffected limbs. Doppler ultrasonography helps evaluate blood flow in the distal aorta and femoral arteries.
Histopathological 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 of ischemic neuromyopathy consists of analgesic administration, nursing care, and treatment of any underlying disease (eg, cardiomyopathy). Thrombolytic therapy, such as administration of streptokinase or tissue plasminogen activator, does not improve the rate of survival to discharge (1). Anticoagulants, such as unfractionated heparin or low-molecular-weight heparin, are used to decrease continued thrombus formation. Neurological deficits might improve within 2–3 weeks after starting treatment; however, 6 months might be required for complete recovery. Permanent deficits are possible.
Approximately 60% of cats with ischemic neuromyopathy die or are euthanized during the initial episode (1). In cats that survive, the long-term prognosis is guarded (median 12 months) because of the underlying heart disease and high risk of thromboembolism recurrence.
For More Information
Feline Aortic Thromboembolism (FATE or Saddle Thrombus). Veterinary Partner, VIN.
Also see pet owner content regarding vascular disorders of the peripheral nerves in dogs and cats.
References
Guillaumin J. Feline aortic thromboembolism: recent advances and future prospects. J Feline Med Surg. 2024;26(6):1098612X241257878. doi:10.1177/1098612X241257878
