Peripheral nerve disease in dogs – neuropathy and weakness

Overview

The location of damage determines the signs

Neuropathy may affect a nerve running to a limb or the face, for example. Degeneration of several nerves can cause weakness and muscle wasting in all limbs. When a nerve's communication is interrupted, the muscle it controls also malfunctions.

The central nervous system, by contrast, comprises the brain and spinal cord. A neurological examination first establishes which part of the nervous system fits the signs. Difficulty walking alone therefore does not establish whether the problem lies in the spinal cord, a peripheral nerve or muscle.

Acute nerve root inflammation can rapidly progress to paralysis of all limbs. Recovery is nevertheless possible. Some chronic degenerative neuropathies instead worsen gradually. A single recovery time cannot be applied to all these diseases.

Causes

Inflammation and nerve degeneration

A peripheral nerve can be damaged by infection or an abnormal immune response. In acute polyradiculoneuritis, inflammation particularly affects the ventral nerve roots leaving the spinal cord and the peripheral nerves. The name polyradiculoneuritis means inflammation of many nerve roots.

Raw chicken is a risk factor associated with this acute disease. A possible explanation is an immune response triggered by Campylobacter in contaminated meat. Individual cases following vaccination have been described, but a causal relationship has not been established.

In chronic inflammatory demyelinating polyneuropathy, the nerve's myelin insulation is damaged. Chronic axonal degeneration in an older dog instead causes widespread damage to nerve fibres.

Injury, underlying disease or a tumour

In an accident, a nerve can be stretched, bruised or severed. Brachial plexus avulsion can result from injury around the neck and shoulder. The sciatic nerve can be damaged with a fracture around the hip. Damage can also be associated with fracture surgery. An underactive thyroid can be associated with neuropathy. A nerve sheath tumour can also cause local nerve damage.

In delayed organophosphate poisoning, nerves degenerate. A tumour outside the nervous system can sometimes trigger paraneoplastic neuropathy.

Risk factors

Peripheral nerve diseases occur at different ages, but predisposition depends on the disease form. Chronic axonal degeneration and associated laryngeal paralysis typically affect middle-aged or older dogs. Laryngeal paralysis occurs particularly in large dogs, such as Labrador and Golden Retrievers.

LPN1, LPN2 and LPPN3 genetic tests are available for Leonbergers. Distal polyneuropathy in Rottweilers has been diagnosed in both sexes at 1–4 years of age. This form does not represent every nervous system disease in Rottweilers.

Protozoal nerve root inflammation in a puppy can result from Neospora or Toxoplasma infection. Signs may begin at 3–8 weeks of age.

Sensory ganglioneuritis, inflammation of sensory nerve ganglia, can occur in different breeds. Siberian Huskies have an increased risk. Affected dogs are typically 1–6 years old.

Typical symptoms

Signs may be localised or spread to several limbs. At home, you may notice:

• A short-strided gait and hindlimb weakness.
• Your dog cannot remain standing or support their body.
• A paw drags on the ground and weight bearing is abnormal.
• Visible muscle wasting.
• A hoarse bark or noisy breathing.
• Difficulty swallowing, regurgitation or coughing.
• Facial asymmetry or difficulty blinking.

Acute nerve root inflammation can progress from hindlimb signs to flaccid paralysis of all limbs within 1–2 days. Muscle wasting can already be severe within 10–14 days. Alertness and appetite may nevertheless remain normal. Pain sensation is also preserved in this form. Tail movement, urination and defaecation usually remain normal.

Neuropathy associated with hypothyroidism may occur alongside obesity and hair loss. Sometimes, however, neurological signs are its only visible features. Pain and weakness in one leg caused by a nerve sheath tumour can resemble a bone or muscle injury.

In sensory ganglioneuritis, walking may be uncoordinated without true limb weakness. Pain sensation may be reduced or absent in the limbs and face. Some dogs also show abnormal sensitivity to touch and self-injury.

Complications and consequences

Breathing and swallowing can be endangered

Severe acute nerve root inflammation can cause respiratory paralysis. Laryngeal paralysis can form part of a wider polyneuropathy in an older dog, called GOLPP. Oesophageal dysfunction increases the risk of inhaling food or water. Aspiration pneumonia can follow.

A dragging limb with reduced sensation can be injured or chewed by the dog. Amputation of a severely damaged limb may sometimes be necessary. An extending nerve sheath tumour can also compress the spinal cord.

Recovery varies with the damage

In acute nerve root inflammation, the dog's condition may continue to worsen during the first 10 days. If breathing remains stable, function usually improves slowly over the following 1–2 months.

Improvement in acute polyradiculoneuritis often starts within 3 weeks of signs beginning. Full recovery can take 2–6 months. A severely affected dog with considerable muscle loss may retain deficits.

A bruised nerve has a better prognosis than complete nerve root avulsion. In chronic axonal degeneration, neurological signs generally worsen slowly. The recovery period measured in months for acute inflammation is therefore not used as the prognosis for degenerative disease.

Diagnosis at the vet

First locating the nervous system lesion

Your vet assesses alertness, movement, postural reactions, reflexes and pain sensation. Cranial nerve examination assesses functions including facial movement and swallowing. In acute polyradiculoneuritis, spinal reflexes are weak or absent.

Blood tests can look for underlying diseases explaining weakness. Thyroid function or possible infection is investigated where needed. Myasthenia gravis, botulism, muscle disease and poisoning can also cause similar signs.

Electrical tests and samples

Electromyography, or EMG, can reveal muscle changes consistent with loss of nerve supply. Nerve conduction velocity testing examines signal transmission along a peripheral nerve. In chronic demyelinating polyneuropathy, conduction may slow even when EMG is normal. The tests therefore complement one another.

A 2024 investigation included 71 dogs with suspected acute polyradiculoneuritis. Electrical tests detected abnormalities as early as 1–6 days after signs began. Testing therefore does not always need to be postponed simply because onset was recent.

In acute nerve root inflammation, cerebrospinal fluid may have raised protein but a normal cell count. A nerve or muscle biopsy can help define the damage type. Imaging may be needed if a problem around the spine is suspected, for example. Laryngeal paralysis is diagnosed by examining laryngeal movement in a sedated dog.

Investigations of predominantly sensory nerve disease can specifically measure sensory nerve conduction. A sensory nerve biopsy may show loss of myelinated nerve fibres and scarring. This investigates a different damage mechanism from disease reducing muscle strength alone.

Treatment

Treatment follows the diagnosis

Your vet plans treatment according to whether the problem is inflammation, injury or an underlying disease. Supportive care is the foundation of treatment for acute idiopathic polyradiculoneuritis. Corticosteroids do not benefit this form. Signs of chronic inflammatory demyelinating polyneuropathy, however, may improve with a corticosteroid. In the chronic form, signs can return after treatment ends.

Neuropathy associated with hypothyroidism is treated by addressing the hormone deficiency. Tumour-associated neuropathy may improve if treatment of the underlying tumour succeeds. A severed nerve may require prompt surgery. There is little evidence for benefit from anti-inflammatory medicines alone in traumatic nerve injury.

Protecting breathing, nutrition and skin

A dog with acutely worsening weakness has breathing monitored in hospital. Respiratory paralysis may require a ventilator. Laryngeal paralysis can be treated with surgery widening the airway. Surgery does not, however, correct widespread nerve degeneration.

A dog unable to move is provided with padded, clean and dry bedding. Their position is changed if they cannot turn themselves. Help may be needed with eating, drinking and toileting. Swallowing and feeding position are assessed separately if aspiration risk is increased.

Rehabilitation maintains function

Guided physiotherapy may include passive joint movements and supported standing and walking. Long-term care of nerve injury aims to reduce muscle wasting and maintain joint movement. A damaged limb may be protected with a bandage or splint. Nerve function may return only once a nerve fibre has regrown from the injury site to the muscle. Scar tissue or widely separated severed nerve ends can prevent healing.

Prevention

The cause of every neuropathy is not known, so there is no single preventive measure for all of them. Avoiding the risk associated with raw chicken reduces exposure to a factor linked to acute nerve root inflammation. This does not mean every peripheral nerve disease is food-related.

Prevention of hereditary diseases uses genetic tests relevant to the breed. Some Leonberger breeding guidelines require polyneuropathy genetic results before mating. Suitability of a genetic test for the breed matters because the significance of every test has not been studied in every breed. A result for one tested gene change is therefore not a general certificate of a healthy nervous system.

Important for dog owners

Record whether weakness began suddenly or gradually and which limb was affected first. Take a short video of walking on a safe surface with good grip if your dog can move. Also monitor the bark, breathing, swallowing, paw skin and weight. Laryngeal dysfunction may be the first sign of widespread neuropathy.

Follow the individual turning, feeding and rehabilitation plan. Do not test limb pain sensation yourself by squeezing the toes. In acute nerve root inflammation, pain sensation may remain despite severe paralysis. A preserved appetite does not remove the need to monitor breathing either.

Report a new cough, difficulty swallowing or altered breathing immediately. Aspiration pneumonia associated with laryngeal paralysis is possible even without surgery. Keep test results and the exact diagnosis so that later assessments can establish which type of neuropathy occurred.

Frequently asked questions

Does neuropathy always mean permanent paralysis?

No. Different nerve diseases follow different courses. Acute polyradiculoneuritis can resolve completely within 2–6 months. In traumatic nerve injury, separation of the nerve ends or scar tissue blocking healing makes recovery harder. Prognosis therefore requires the cause and extent of the damage.

Can a dog be alert despite being unable to walk?

In acute nerve root inflammation, alertness and appetite can remain normal. Pain sensation can also be preserved. The disease can nevertheless paralyse breathing muscles in its most severe form. Inability to move and rapidly progressive weakness therefore require assessment even if your dog follows their surroundings and eats willingly.

Why use a muscle electrical test for suspected nerve disease?

EMG can show changes in muscle caused by loss of nerve supply. Nerve conduction velocity testing provides different information about nerve function. In chronic demyelinating polyneuropathy, conduction can be slow even when EMG is normal. Rather than relying on one measurement, diagnosis therefore combines signs, examination findings and any additional samples needed.

Do corticosteroids help every inflammatory neuropathy?

Corticosteroids have not shown benefit in acute idiopathic polyradiculoneuritis. Its treatment centres on supportive care and rehabilitation. Signs of chronic inflammatory demyelinating polyneuropathy, however, often improve with a corticosteroid. Treatment decisions are therefore not made from the word inflammation alone: your vet distinguishes these forms through investigation.

Can a hoarse bark be linked to weak legs?

Laryngeal paralysis can be the first sign of widespread polyneuropathy in an older dog. The same syndrome can later cause limb weakness and impaired movement coordination. Laryngeal surgery may ease breathing but does not restore the larynx's own function.