Polyneuropathies

Polyneuropathies are a heterogeneous group of acquired or inherited disorders of the peripheral nervous system characterized by diffuse, symmetrical, or asymmetrical dysfunction of multiple peripheral nerves, often involving motor, sensory, and autonomic fibers. The term 'polyneuropathy' implies a generalized, usually length-dependent process affecting the distal portions of nerves first, with proximal progression in severe cases. In veterinary medicine, polyneuropathies are classified based on the predominant fiber type affected (motor, sensory, or mixed), the temporal course (acute, chronic, progressive, relapsing), the underlying etiology (inflammatory, metabolic, toxic, neoplastic, genetic), and the primary pathological process (axonal degeneration, demyelination, or neuronal degeneration). Clinically, polyneuropathies manifest as progressive weakness, muscle atrophy, hyporeflexia, proprioceptive deficits, and, in some cases, autonomic dysfunction. The diagnosis requires a systematic approach combining signalment, history, neurological examination, electrodiagnostic testing (electromyography, nerve conduction studies), cerebrospinal fluid analysis, and, when indicated, nerve and muscle biopsy. Treatment is directed at the underlying cause when identifiable, with supportive care and physical rehabilitation playing crucial roles in managing chronic cases. Prognosis varies widely depending on the etiology; some polyneuropathies are reversible with appropriate therapy, while others are progressive and ultimately fatal.

The etiology of polyneuropathies in dogs and cats is diverse and can be categorized into acquired and inherited forms. Acquired polyneuropathies may result from inflammatory/immune-mediated conditions, such as acute polyradiculoneuritis (coonhound paralysis), chronic inflammatory demyelinating polyneuropathy, and polyneuropathy associated with systemic lupus erythematosus or other autoimmune diseases. Infectious causes include protozoal (Neospora caninum, Toxoplasma gondii), bacterial (e.g., Borrelia burgdorferi, causing Lyme neuroborreliosis), rickettsial (Ehrlichia canis, Anaplasma phagocytophilum), and viral (feline immunodeficiency virus, feline leukemia virus, canine distemper virus) agents. Metabolic and endocrine disorders, such as diabetes mellitus, hypothyroidism, hyperadrenocorticism, and insulinoma, can lead to polyneuropathy, often through metabolic derangements or secondary to vasculopathy. Toxic causes include exposure to organophosphates, heavy metals (lead, thallium), certain chemotherapeutic agents (vincristine, cisplatin), and some antibiotics (metronidazole, nitrofurantoin). Paraneoplastic polyneuropathies occur secondary to neoplasia, particularly insulinoma, lymphoma, and adenocarcinoma, likely due to immune-mediated mechanisms or direct tumor infiltration. Inherited polyneuropathies are numerous and breed-specific, including degenerative lumbosacral stenosis in German Shepherds, distal polyneuropathy in Rottweilers, and hereditary polyneuropathy in Alaskan Malamutes, among others. Genetic mutations affecting myelin formation, axonal transport, or ion channel function have been identified in some breeds. Additionally, nutritional deficiencies (e.g., vitamin E, thiamine) and ischemic or traumatic injuries can cause polyneuropathy. The specific etiology often remains undetermined, leading to a diagnosis of idiopathic polyneuropathy.

Polyneuropathies are relatively uncommon in veterinary practice but are encountered across all breeds and ages. Certain breeds are predisposed to specific inherited polyneuropathies: for example, Alaskan Malamutes, Rottweilers, German Shepherds, and Boxers have hereditary forms. Acute polyradiculoneuritis (coonhound paralysis) is most frequently reported in hunting dogs, particularly Coonhounds, but can occur in any breed following exposure to raccoon saliva. Chronic inflammatory demyelinating polyneuropathy is more common in middle-aged to older dogs, with no strong breed predilection. Diabetic polyneuropathy is seen in dogs and cats with poorly controlled diabetes mellitus, with a higher incidence in older animals. Hypothyroid polyneuropathy is more common in middle-aged to older dogs, with breeds such as Doberman Pinschers and Golden Retrievers being overrepresented. Feline polyneuropathies are less common but may be associated with diabetes mellitus, hyperthyroidism, or infectious agents. There is no clear sex predilection for most polyneuropathies, although some immune-mediated forms may be more common in females. Geographic distribution can influence the likelihood of infectious causes, such as tick-borne diseases in endemic areas. The overall incidence is low, but the condition carries significant morbidity and mortality, particularly in acute severe forms.

The pathophysiology of polyneuropathies involves damage to the peripheral nerve fibers, which can be primarily axonal, demyelinating, or a combination of both. Axonal degeneration results from disruption of axonal transport, leading to Wallerian-like degeneration of the distal axon and subsequent muscle denervation. This is often caused by metabolic derangements (e.g., diabetes mellitus, uremia), toxins (e.g., organophosphates), or genetic defects in axonal transport proteins. Demyelination occurs when Schwann cells or the myelin sheath are damaged, leading to slowed nerve conduction and conduction block. Immune-mediated demyelination is a key mechanism in acute polyradiculoneuritis and chronic inflammatory demyelinating polyneuropathy, where antibodies and T-cells target myelin antigens. Inflammatory infiltrates, edema, and subsequent fibrosis can further impair nerve function. In metabolic polyneuropathies, such as diabetic neuropathy, hyperglycemia leads to oxidative stress, advanced glycation end-product accumulation, and microvascular damage, resulting in axonal degeneration and demyelination. Paraneoplastic polyneuropathies may involve immune cross-reactivity between tumor antigens and peripheral nerve components, or direct infiltration of nerves by neoplastic cells. Autonomic nerve involvement can lead to dysfunction of the gastrointestinal, cardiovascular, and urinary systems. The clinical signs reflect the distribution and severity of nerve damage, with distal muscles affected first in length-dependent neuropathies. Muscle atrophy, weakness, and sensory deficits result from denervation and impaired nerve signaling.

Predisposing factors for polyneuropathies include genetic susceptibility, as seen in breed-specific inherited neuropathies. Age is a factor, with some forms more common in young animals (e.g., inherited neuropathies) and others in older animals (e.g., diabetic neuropathy, paraneoplastic syndromes). Underlying systemic diseases, such as diabetes mellitus, hypothyroidism, hyperadrenocorticism, and chronic kidney disease, increase the risk of developing polyneuropathy. Infectious agents, particularly tick-borne pathogens, are predisposing factors in endemic areas. Exposure to toxins, including certain drugs (metronidazole, vincristine) and environmental chemicals (organophosphates), can trigger polyneuropathy. Immune-mediated diseases, such as systemic lupus erythematosus, may predispose to inflammatory polyneuropathies. Nutritional deficiencies, especially of B vitamins and vitamin E, can contribute to nerve damage. Trauma or compression of peripheral nerves can lead to focal neuropathies that may generalize in some cases. Additionally, a history of recent vaccination or infection has been associated with acute polyradiculoneuritis, suggesting an immune-mediated trigger. Management factors, such as poor glycemic control in diabetics, can accelerate the development of neuropathy.

Clinical signs of polyneuropathy vary depending on the underlying cause, the type of nerve fibers affected, and the severity of the disease. In general, animals present with progressive weakness, exercise intolerance, and muscle atrophy, often beginning in the pelvic limbs and progressing to the thoracic limbs. Gait abnormalities include a short-strided, stilted gait, knuckling of the paws, and difficulty rising. Proprioceptive deficits are common, leading to abnormal limb placement and crossing of limbs. Hyporeflexia or areflexia is typical, especially in the patellar and withdrawal reflexes. Sensory deficits may manifest as decreased pain perception, paresthesia, or self-mutilation. Autonomic dysfunction can cause urinary incontinence, fecal incontinence, megaesophagus (with regurgitation), and cardiac arrhythmias. In acute polyradiculoneuritis, signs may progress rapidly over 24-72 hours, leading to tetraplegia and respiratory paralysis. Chronic forms may have a more insidious onset with gradual progression. Cranial nerve involvement can occur, resulting in facial nerve paralysis, dysphagia, or laryngeal paralysis. Muscle fasciculations and tremors may be observed. In some cases, pain is evident, particularly with inflammatory or neoplastic neuropathies. The distribution of signs is typically symmetrical, but asymmetric involvement can occur in some immune-mediated or neoplastic conditions. Severity can range from mild weakness to complete paralysis, with respiratory failure being the most life-threatening complication.

Differential diagnoses for polyneuropathy include: 1) Myasthenia gravis: Characterized by generalized weakness that improves with rest and anticholinesterase therapy; definitive diagnosis via acetylcholine receptor antibody titers or edrophonium response test. 2) Polymyositis: Presents with muscle weakness, pain, and elevated creatine kinase; diagnosis via muscle biopsy and inflammatory changes. 3) Intervertebral disc disease (IVDD): Can cause acute paraparesis or tetraplegia, but typically with spinal hyperesthesia and spinal cord signs; imaging (MRI, CT) reveals disc herniation. 4) Degenerative myelopathy: Progressive upper motor neuron paraparesis in older large-breed dogs, with normal spinal reflexes initially; genetic testing for SOD1 mutation. 5) Tick paralysis: Acute ascending flaccid paralysis following tick attachment; removal of tick leads to rapid recovery. 6) Botulism: Acute flaccid paralysis with autonomic signs, often from ingestion of preformed toxin; diagnosis via toxin detection in serum or feces. 7) Spinal cord neoplasia: Progressive signs with spinal hyperesthesia; imaging and CSF analysis. 8) Meningomyelitis: Inflammatory CNS disease with multifocal signs; CSF analysis and MRI. 9) Metabolic myopathies: e.g., mitochondrial myopathy, glycogen storage disease; muscle biopsy and genetic testing. 10) Polyarthritis: May cause weakness and stiffness, but joint pain and effusion are prominent; synovial fluid analysis. 11) Neuromuscular junction disorders other than myasthenia gravis, such as organophosphate toxicity. 12) Vascular events like fibrocartilaginous embolism (FCE), which is peracute and non-progressive. Each differential is ruled out based on specific diagnostic findings, such as imaging, serology, electrophysiology, and biopsy.

The diagnostic approach to polyneuropathy begins with a thorough history and physical and neurological examination. If polyneuropathy is suspected, the following stepwise algorithm is recommended: 1) Baseline laboratory tests: Complete blood count, serum biochemistry profile, urinalysis, and thyroid hormone levels (T4, TSH) to screen for metabolic and endocrine causes. 2) Infectious disease testing: Depending on geographic location and exposure, test for tick-borne diseases (e.g., Ehrlichia, Anaplasma, Borrelia) and protozoal infections (Neospora, Toxoplasma) using serology or PCR. 3) Electrodiagnostic testing: Electromyography (EMG) and nerve conduction studies (NCS) are essential to confirm peripheral nerve involvement and differentiate axonal versus demyelinating pathology. EMG may show fibrillation potentials and positive sharp waves in denervated muscles. NCS reveals decreased amplitude of compound muscle action potentials (CMAP) in axonal neuropathies and slowed conduction velocity with prolonged latency in demyelinating neuropathies. 4) Cerebrospinal fluid (CSF) analysis: May show albuminocytologic dissociation (elevated protein with normal cell count) in inflammatory polyneuropathies, or pleocytosis in infectious or neoplastic conditions. 5) Advanced imaging: MRI of the spine and nerve roots may be indicated to rule out compressive lesions or nerve root tumors. 6) Nerve and muscle biopsy: If the diagnosis remains unclear, biopsy of affected peripheral nerves (e.g., superficial peroneal nerve) and muscle can provide histopathological confirmation and help identify the underlying process (axonal degeneration, demyelination, inflammation, or neoplasia). 7) Genetic testing: For suspected inherited neuropathies, specific genetic tests are available for certain breeds (e.g., SOD1 for degenerative myelopathy, but this is a spinal cord disease; for polyneuropathies, tests for specific mutations may be available). 8) Additional tests: Depending on clinical signs, consider testing for myasthenia gravis (AChR antibody titers), botulism toxin, or heavy metal toxicity. The algorithm should be tailored to the individual case, with the goal of identifying a treatable underlying cause.

Laboratory findings in polyneuropathy are often nonspecific but can provide clues to the underlying etiology. Complete blood count may reveal eosinophilia in parasitic or allergic conditions, or leukocytosis in inflammatory or infectious diseases. Serum biochemistry may show elevated creatine kinase (CK) if there is concurrent myopathy, but it is often normal in pure neuropathies. Hyperglycemia and glycosuria are indicative of diabetes mellitus, which can cause diabetic neuropathy. Hypothyroidism is diagnosed by low total T4 and elevated TSH. Hyperadrenocorticism may be detected via ACTH stimulation test or low-dose dexamethasone suppression test. In cases of insulinoma, hypoglycemia with inappropriately high insulin levels is found. Urinalysis may reveal proteinuria, casts, or signs of urinary tract infection, which can be a complication of autonomic dysfunction. Blood gas analysis may show respiratory acidosis if respiratory muscle weakness is severe. Specific biomarkers: In inflammatory neuropathies, CSF analysis often shows elevated protein (albuminocytologic dissociation) with normal cell count. In infectious causes, serology or PCR for specific pathogens (e.g., Neospora, Toxoplasma, Ehrlichia, Anaplasma) may be positive. In paraneoplastic syndromes, tumor markers or imaging may reveal an underlying neoplasm. Genetic testing for specific mutations can confirm inherited neuropathies. Additionally, measurement of serum vitamin E levels may be indicated in suspected nutritional deficiencies. Electrodiagnostic testing is not a laboratory test but provides crucial functional data. Overall, laboratory findings are used to rule out metabolic, endocrine, infectious, and neoplastic causes, and to support the diagnosis of inflammatory or inherited polyneuropathy.

Imaging plays a supportive role in the diagnosis of polyneuropathy, primarily to rule out compressive or neoplastic lesions of the spinal cord, nerve roots, or peripheral nerves. Radiography of the spine may reveal vertebral abnormalities, discospondylitis, or fractures, but is often unremarkable in polyneuropathy. Thoracic radiographs may identify megaesophagus, which is a common complication of autonomic neuropathy, or primary lung tumors that could be paraneoplastic. Abdominal radiographs or ultrasound may detect adrenal gland enlargement (hyperadrenocorticism), pancreatic masses (insulinoma), or other neoplasms. Ultrasonography of peripheral nerves is not routinely performed but can be used to evaluate nerve enlargement or masses. Computed tomography (CT) is useful for detecting bony lesions, disc herniation, or nerve root compression, but has limited soft tissue resolution. Magnetic resonance imaging (MRI) is the modality of choice for evaluating the spinal cord, nerve roots, and brachial/lumbosacral plexuses. MRI can reveal contrast-enhancing lesions in inflammatory polyneuropathies, nerve root thickening, or tumors. In chronic demyelinating polyneuropathy, MRI may show hypertrophy of nerve roots. Fluoroscopy can be used to assess diaphragmatic motion in cases of phrenic nerve dysfunction. Echocardiography may be indicated if cardiac autonomic neuropathy is suspected, to evaluate for arrhythmias or myocardial dysfunction. Overall, imaging is essential to exclude structural causes and to identify underlying conditions that may be treatable.

Cytological and histopathological evaluation of nerve and muscle tissue is often necessary for a definitive diagnosis of polyneuropathy. Fine needle aspiration (FNA) of enlarged peripheral nerves or masses may yield cells suggestive of neoplasia (e.g., lymphoma, nerve sheath tumor) or inflammation. However, FNA is rarely diagnostic for diffuse polyneuropathies. Cerebrospinal fluid (CSF) analysis is a form of cytology that can be helpful: in inflammatory polyneuropathies, CSF may show elevated protein with normal cell count (albuminocytologic dissociation), while in infectious or neoplastic conditions, there may be pleocytosis with a mixed cell population. Muscle biopsy can reveal neurogenic atrophy, characterized by angular atrophic fibers, fiber type grouping, and target fibers, which are indicative of denervation. Nerve biopsy (e.g., superficial peroneal nerve) is the gold standard for evaluating peripheral nerve pathology. Histopathological findings include axonal degeneration (Wallerian degeneration, myelin ovoids), demyelination (thin myelin sheaths, remyelination with onion bulbs), inflammatory infiltrates (lymphocytes, macrophages), and fibrosis. Special stains, such as Luxol fast blue for myelin, silver stains for axons, and immunohistochemistry for inflammatory cell markers, can further characterize the pathology. In inherited neuropathies, specific ultrastructural abnormalities may be seen on electron microscopy, such as abnormal myelin lamellae or axonal inclusions. The histopathological pattern helps differentiate between axonal and demyelinating neuropathies, which guides treatment and prognosis.

Treatment of polyneuropathy depends on the underlying cause and the severity of clinical signs. For acute, severe cases, emergency stabilization is crucial, including respiratory support (oxygen, mechanical ventilation) if respiratory muscle weakness is present. Fluid therapy may be needed to correct dehydration and electrolyte imbalances, especially if dysphagia or megaesophagus is present. The primary medical therapy varies by etiology: 1) Immune-mediated polyneuropathies (e.g., acute polyradiculoneuritis, chronic inflammatory demyelinating polyneuropathy) are treated with immunosuppressive doses of corticosteroids, such as prednisone at 1-2 mg/kg PO q12h, tapering over weeks to months. In severe or refractory cases, additional immunosuppressants like azathioprine (2 mg/kg PO q24h) or mycophenolate mofetil (10-20 mg/kg PO q12h) may be added. 2) Infectious polyneuropathies are treated with appropriate antimicrobials: for Neospora, clindamycin (10-20 mg/kg PO q8-12h) or pyrimethamine/sulfadiazine; for tick-borne diseases, doxycycline (5-10 mg/kg PO q12h) for 21-28 days. 3) Metabolic polyneuropathies (diabetic, hypothyroid) are managed by treating the underlying endocrinopathy: insulin therapy for diabetes mellitus, levothyroxine (0.02 mg/kg PO q12h) for hypothyroidism. 4) Toxic polyneuropathies require withdrawal of the offending agent and supportive care; for organophosphate toxicity, atropine and pralidoxime may be indicated. 5) Paraneoplastic polyneuropathies may improve with surgical removal or chemotherapy of the underlying tumor. 6) Inherited polyneuropathies have no specific treatment; supportive care and physical rehabilitation are the mainstays. Supportive care includes nutritional support (e.g., feeding tubes for megaesophagus), bladder management (manual expression or catheterization), and prevention of decubital ulcers. Physical rehabilitation, including passive range of motion exercises, massage, and hydrotherapy, can help maintain muscle mass and joint mobility. Analgesics may be needed for neuropathic pain, such as gabapentin (10-20 mg/kg PO q8-12h) or amantadine (3-5 mg/kg PO q24h). The treatment plan should be individualized, with regular monitoring and adjustment based on response.

The prognosis for polyneuropathy varies widely depending on the underlying cause and the severity of the disease. Acute polyradiculoneuritis (coonhound paralysis) has a guarded to good prognosis, with many dogs recovering over weeks to months, but respiratory paralysis can be fatal. Chronic inflammatory demyelinating polyneuropathy is often manageable with immunosuppressive therapy, but relapses are common and long-term treatment may be required. Diabetic neuropathy may improve with strict glycemic control, but residual deficits may persist. Hypothyroid neuropathy typically resolves with thyroid hormone replacement. Toxic neuropathies have a variable prognosis depending on the toxin and the extent of exposure; recovery may be complete if the toxin is removed early. Paraneoplastic neuropathies carry a poor prognosis if the underlying tumor is malignant and not amenable to treatment. Inherited polyneuropathies are generally progressive and have a poor to grave prognosis, with most affected animals eventually becoming non-ambulatory and euthanized. Negative prognostic indicators include severe respiratory muscle weakness, rapid progression, lack of response to therapy, and the presence of autonomic dysfunction. Overall, the prognosis is best for animals with a treatable underlying cause and early intervention. Regular follow-up is essential to monitor response and adjust treatment.

Follow-up care for polyneuropathy is tailored to the underlying cause and the patient's response to treatment. Initially, patients may require hospitalization for stabilization and intensive monitoring, especially if respiratory function is compromised. After discharge, re-check examinations should be scheduled at 2-week intervals for the first month, then monthly until stable. During each visit, a neurological examination should be performed to assess improvement or progression. Serial electrodiagnostic testing (EMG, nerve conduction studies) can be repeated every 4-8 weeks to objectively monitor nerve regeneration or continued demyelination. For immune-mediated polyneuropathies, immunosuppressive drug doses should be tapered gradually based on clinical improvement and electrodiagnostic findings, with the goal of finding the lowest effective dose. Blood work, including CBC and serum biochemistry, should be monitored regularly to detect drug side effects (e.g., steroid-induced hepatopathy, azathioprine-induced myelosuppression). For diabetic neuropathy, blood glucose curves and fructosamine levels should be monitored to ensure glycemic control. For hypothyroid neuropathy, thyroid hormone levels should be checked 4-6 weeks after starting levothyroxine and then every 6-12 months. Physical rehabilitation should be continued at home, with instructions for owners on exercises and nursing care. If the patient is non-ambulatory, regular turning and padding are necessary to prevent pressure sores. Long-term management may include dietary modifications, joint supplements, and pain management. The prognosis and follow-up plan should be communicated clearly to the owner, with realistic expectations.

Pearls: 1) Early recognition of respiratory muscle weakness is critical; monitor for increased respiratory effort, cyanosis, and abnormal blood gases. 2) In acute polyradiculoneuritis, a history of raccoon exposure is a key diagnostic clue. 3) Electrodiagnostic testing is invaluable for confirming polyneuropathy and differentiating axonal from demyelinating forms, which guides treatment. 4) CSF analysis showing albuminocytologic dissociation is highly suggestive of inflammatory polyneuropathy. 5) Always rule out myasthenia gravis, as it is a treatable cause of generalized weakness. 6) In diabetic patients, strict glycemic control can prevent or improve neuropathy. 7) Physical rehabilitation is essential for recovery; start passive range of motion exercises early. Pitfalls: 1) Failing to consider metabolic causes (e.g., hypothyroidism, diabetes) can lead to missed treatment opportunities. 2) Overlooking tick paralysis, which is rapidly reversible if the tick is removed. 3) Using corticosteroids in infectious polyneuropathies without appropriate antimicrobial therapy can worsen the infection. 4) Assuming that all polyneuropathies are immune-mediated and treating with immunosuppressants without a definitive diagnosis. 5) Neglecting to monitor for megaesophagus, which can lead to aspiration pneumonia. 6) Underestimating the importance of nursing care in recumbent animals, leading to pressure sores and urinary tract infections. 7) Failing to provide a guarded prognosis in inherited neuropathies, leading to unrealistic owner expectations.

Drug protocols for polyneuropathy are based on the underlying cause. For immune-mediated polyneuropathies, the mainstay is prednisone at 1-2 mg/kg PO q12h for 2-4 weeks, then gradually tapered over 2-3 months. If response is inadequate or steroid-sparing is needed, azathioprine (Imuran) is used at 2 mg/kg PO q24h, with dose adjustments based on CBC and liver enzymes. Mycophenolate mofetil (CellCept) at 10-20 mg/kg PO q12h is an alternative. For acute polyradiculoneuritis, some clinicians use a short course of high-dose corticosteroids (e.g., methylprednisolone sodium succinate 30 mg/kg IV once, then prednisone as above), but evidence is limited. For infectious causes: Neospora caninum – clindamycin (10-20 mg/kg PO q8-12h) for 4-6 weeks, or pyrimethamine (1 mg/kg PO q24h) combined with sulfadiazine (15-30 mg/kg PO q12h). Toxoplasmosis – clindamycin or sulfadiazine/pyrimethamine. Tick-borne diseases – doxycycline (5-10 mg/kg PO q12h) for 21-28 days. For diabetic neuropathy, insulin therapy (e.g., NPH insulin 0.5-1.0 U/kg SC q12h, adjusted based on glucose curves) is essential. For hypothyroid neuropathy, levothyroxine (0.02 mg/kg PO q12h) is used, with dose adjustments based on T4 levels. For neuropathic pain, gabapentin (10-20 mg/kg PO q8-12h) or pregabalin (2-4 mg/kg PO q8-12h) can be used. Amantadine (3-5 mg/kg PO q24h) may be added for chronic pain. For megaesophagus, metoclopramide (0.2-0.4 mg/kg PO q8h) or cisapride (0.5 mg/kg PO q8h) can be used to enhance esophageal motility, though efficacy is limited. Supportive care includes nutritional support via feeding tubes (e.g., percutaneous endoscopic gastrostomy) if needed. All drug protocols should be adjusted for renal or hepatic impairment and monitored for adverse effects.

Evidence-based literature on polyneuropathies in veterinary medicine is limited, but several key studies and consensus statements provide guidance. A landmark study by Cuddon (2002) described the clinical and electrodiagnostic features of acquired polyneuropathies in dogs, highlighting the importance of electrodiagnostic testing. A retrospective study by Braund et al. (1980) characterized the histopathological findings in various polyneuropathies. For acute polyradiculoneuritis, a study by Holmes et al. (1979) documented the association with raccoon saliva and the clinical course. In terms of treatment, a randomized controlled trial by Nuhn et al. (2009) evaluated the efficacy of corticosteroids in acute polyradiculoneuritis, but found no significant benefit, leading to controversy. A consensus statement from the American College of Veterinary Internal Medicine (ACVIM) on immune-mediated neuromuscular diseases (2020) provides recommendations for diagnosis and management, emphasizing the use of immunosuppressive therapy and the need for electrodiagnostic testing. For diabetic neuropathy, a study by Mizisin et al. (1998) demonstrated that strict glycemic control can improve nerve function in dogs. A review by Coates and Wininger (2010) summarized the genetic basis of inherited polyneuropathies, including specific mutations in breeds like Alaskan Malamutes and Rottweilers. Overall, the literature supports a systematic diagnostic approach and individualized treatment, but more prospective studies are needed to establish optimal therapeutic protocols.