PNS Flashcards
Nerves are collections of:
axons/dendrites outside the CNS
Ganglia are collections of:
neuronal cell bodies outside the CNS
What main diseases affect the PNS?
Inflammatory Degenerative Metabolic Toxic Neoplastic
A Coonhound presents to your clinic with tetraparesis. The owner said the dog has been increasingly less mobile since an altercation with a raccoon a couple weeks ago, and he’s looking rather skinny lately. What is the pathogenesis?
Demyelination and influx of inflammatory cells to the ventral nerve roots and peripheral nerves.
This is idiopathic acute polyradiculoneuritis. Can occur after a bite or scratch from a raccoon, or idiopathic. Compared to Guillain-Barre in humans. Affected dogs will recover with time, but will have extensive dennervation atrophy.
You arrive at a farm to examine a horse with tail paralysis, urinary incontinence, fecal retention, and hind limb ataxia. The owner states the horse hasn’t been injured and hasn’t gotten into any toxins. Hearing this, you know the prognosis is poor. What do you expect to see on necropsy?
Thickened nerve roots of the cauda equina, and lymphocytic inflammation on histology.
This is neuritis of the cauda equina. Inflammatory cell infiltration and demyelination of the cauda equina and lumbar nerves roots leads to hind end paralysis. Etiology is unknown, but suspected immune-mediated.
A Bouvier de Flandres arrives at your clinic for dry cough, exercise intolerance, and episodes of respiratory distress. The owner also believes that the dog’s voice has changed. Considering the breed, and the fact that there is no history of trauma in the neck, you determine that this condition is hereditary. Clinical signs are attributed to neurogenic atrophy of which muscle?
Cricoarytenoideus dorsalis.
This is canine laryngeal paralysis. Can be congenital or acquired, and is more common in larger breed dogs. Laryngeal paralysis is a component of generalized polyneuropathy and chronic axonal degeneration. Can be unilateral or bilateral.
Trixie, a FS 5 year old Doberman, arrives for her appointment non-weight bearing on her RR leg. After a couple minutes, she begins flexing the hip and stifle on the LR leg, and continues to alternate between legs. The owner states that this has been progressing over the past couple months and she insists the dog sustained no injuries. You perform a neuro exam and find proprioceptive deficits in the pelvic limbs, while the thoracic limbs appear unaffected. Is this disease affecting the nerves or muscles of the pelvic limbs?
Both.
This is dancing doberman disease, an inherited condition. Pathologic changes are found in both nerves and muscles, with neither being confirmed as the primary cause.
*Does not result in severe disability.
A rescue group brings in a 2 year old Rottweiler that is unable to use his front legs, and seems weak in the hind end. You test the dog’s reflexes and find that they are decreased, and you note muscle atrophy of the front legs. What is the likely pathogenesis?
Denervation of distal muscles of the limbs and decreased nerve conduction velocity.
This is distal polyneuropathy of Rottweilers. Can be confirmed on histo with presence of macrophages around the nerve fibers in the distal limbs. Prognosis is poor, although corticosteroids might give temporary relief.
One of your horses has shown brisk, involuntary flexion of the pelvic limbs while walking, and appears to have some muscle atrophy. What nerves are affected?
Peroneal and Tibial nerves.
This is Stringhalt. Axonal degeneration of the peroneal and tibial nerves.
What form of Stringhalt occurs sporadically around the world and it mainly unilateral?
Classic/Ordinary
What form of Stringhalt occurs in outbreaks in a region and affects both pelvic limbs, usually in late summer or autumn when dandelions and mallow are on pasture?
Australian
A cat presents dragging the right thoracic limb on its dorsal surface. On exam, you note endopthalmos and mydriasis of the right eye, along with ipsilateral loss of panniculus reflex. There is no response with a deep pain test of the limb. What is the best treatment option?
Amputation.
This is avulsion of the brachial plexus. Ipsilateral Horner’s and loss of panniculus reflex occur in severe cases. There will also be loss of sensation on the caudal aspect of the limb.
Post operative complication in dogs with docked tails, when attempts by the body to regenerate severed axons fail:
Amputation neuromas
Although calving paralysis has been attributed to compression of the obturator nerve, what actually accounts for most of the paralysis?
Damage to the 6th lumbar nerve root
What is a cardinal sign of diabetic neuropathy in cats?
Hind limb weakness with plantigrade stance
