Polyradiculoneuritis in dogs: weakness and recovery

Overview

This is an acquired peripheral nervous system disorder mainly affecting the nerves that control muscle movement. Idiopathic means that the trigger for inflammation usually cannot be identified. The acute form is one of the most common sudden-onset polyneuropathies in dogs.

The canine disease shares many features with Guillain–Barré syndrome in people. Alertness and appetite may remain normal despite severe limb weakness. Slowly relapsing nerve root inflammation is a separate, rare disease.

In the chronic form, symptoms may improve spontaneously for a time and then return.

The chronic form causes slowly increasing exercise intolerance and weakness. Sensory deficits may also develop in severe disease.

Causes

The immune system is suspected of damaging the dog's own nerve structures. Damage may affect both the nerve fibre and its surrounding myelin sheath. Changes mainly affect motor nerve roots leaving the spinal cord. Tissue samples may show inflammation, loss of myelin and degeneration of nerve fibres.

In a dog eating raw chicken, an immune reaction triggered by Campylobacter in the meat is a possible cause. In North America, a form associated with raccoon saliva is known as coonhound paralysis. However, most dogs develop symptoms without an identifiable exposure of this kind.

One possible mechanism is cross-reaction: an antibody directed against a foreign protein also recognises the dog's own tissues. Respiratory infections have also been suspected as triggers.

Protozoal polyradiculoneuritis develops through a different mechanism from the idiopathic form. Infection most often passes from the mother to her puppies through the placenta. Several puppies in the same litter may be affected.

Risk factors

No clear risk group limited to a particular age or sex has been described. Raw chicken has been identified as a risk factor. Symptoms may start 7–14 days after a raccoon bite or scratch. Repeated raccoon contact is also associated with recurrence in hunting dogs.

Isolated cases have been described after vaccination, but a causal link has not been established. In a case–control study, vaccination was not associated with increased disease risk.

The disease has been described, for example, in a 9-year-old bitch that had eaten raw duck. Another dog treated in the same case report was a 5-year-old neutered male.

Typical symptoms

Initially, hindleg steps may shorten, and flaccid weakness of all four limbs can develop within 1–2 days.

• The hindlegs give way and getting up becomes difficult.

• Weakness spreads to the front legs, leaving your dog lying down.

• Neck muscle weakness makes lifting the head difficult.

• The bark becomes quieter or the voice changes because of laryngeal weakness.

• Facial movements may weaken.

• Muscles become smaller as the disease progresses.

• In severe disease, breathing is shallow or requires obvious effort.

Tail wagging, urination and defaecation usually remain normal. Pain perception is generally preserved. However, some dogs are unusually sensitive when the trunk or limbs are touched. Occasionally, symptoms start in the front legs rather than the hindlegs.

Complications and consequences

Breathing and the effects of immobility

Paralysis of the breathing muscles can be fatal. A dog unable to turn itself may develop pressure sores and broken skin. Severe muscle wasting becomes visible within just 10–14 days. A severely affected dog may not recover completely.

Prolonged lying down increases the risk of partial lung collapse, known as atelectasis. Respiratory secretions may also accumulate in the lungs.

Recovery takes weeks and months

Most dogs start to improve within 3 weeks of symptoms beginning. Full recovery usually takes 2–6 months. Early return of function may be visible after just 7–10 days. Involvement of the breathing muscles worsens the outlook.

In a rehabilitation report involving two dogs, one regained independent walking 25 days after rehabilitation started. The other took 50 days from the start of rehabilitation. The disease may recur later.

Deterioration can continue for up to 10 days after the first symptoms. If breathing remains stable, gradual improvement is seen over the following 1–2 months.

In the protozoal form, stiffness from muscle shortening and severe nerve damage may be permanent. Stiffening of a puppy's hindlegs then indicates a poor outlook for neurological recovery.

Diagnosis at the vet

Neurological examination and ruling out other causes

Diagnosis relies on the history, symptom progression and examination findings consistent with polyneuropathy. The vet often finds reduced or absent limb reflexes. Other causes of similar weakness include myasthenia gravis, botulism and poisoning. In some countries, tick paralysis and snakebite must also be considered.

Blood tests investigate problems including metabolic disorders and infections. Thyroid hormone measurement may be part of investigating other causes of weakness. Neospora and Toxoplasma antibodies help assess possible protozoal infection. Chest X-rays and abdominal ultrasound may help rule out tumour-related causes.

Electrical nerve tests and samples

Electromyography, which records electrical activity in muscles, may reveal disrupted nerve supply. Abnormal findings may not appear during the first 5–7 days. F-waves in nerve conduction testing help identify slowing at nerve root level.

Cerebrospinal fluid collected from the lumbar region may show increased protein with a normal cell count. A nerve or muscle biopsy is sometimes needed. A peripheral nerve biopsy may be non-specific because the most marked inflammation is in the nerve roots.

The cerebrospinal fluid protein change often becomes more evident only at least 7 days after symptoms start. Repetitive stimulation can investigate neuromuscular junction dysfunction. Acetylcholine receptor antibody testing helps distinguish myasthenia gravis.

MRI can look for changes in the spinal cord or discs. A mildly bulging disc may be an incidental finding that does not explain widespread weakness. Electrical nerve tests may be performed under anaesthesia.

Treatment

Breathing support and daily nursing care

The vet plans supportive care and closely monitors breathing muscle function. Respiratory paralysis requires mechanical ventilation. A severely affected dog may need hospital care for weeks. Intravenous fluids can treat dehydration.

Bedding should be padded, clean and dry. Turn your dog regularly if it cannot change position itself. Provide the help needed with eating, drinking and toileting. Offer food in a more upright position so your dog does not eat while lying on its side.

Pain relief may be used if your dog is sore or uncomfortable. Corticosteroids have not shown benefit in acute idiopathic disease.

Rehabilitation is adapted to the strength remaining

An appropriately sized rehabilitation ball can support the trunk during exercises. Underwater treadmill speed and exercise duration are increased as recovery progresses.

Physiotherapy may include passive joint movements and assisted standing and walking. Massage may be included in home rehabilitation. Water-based rehabilitation and exercises for awareness of limb position may form part of the programme.

In the two-dog rehabilitation report, both could lie on their chests without support after 2 weeks. One managed assisted standing by the end of the third week. The other reached this stage by the end of the fifth week.

Passive joint movements aim to prevent stiffness and fibrous tissue formation in the joints. During assisted standing, the legs and paws are placed naturally. Initially, the helper may need to support 75–100% of the dog's weight. The amount of support decreases as strength returns.

Water buoyancy reduces the load on the limbs. When water reaches the greater trochanter of the femur, the reduction in weight-bearing load has been estimated at about 62%. Water resistance increases muscle work during a step.

As rehabilitation progresses, balance board exercises can develop balance and awareness of limb position. Guided stepping over obstacles increases active joint movement and lengthens the stride.

Immune treatments under investigation

The benefits of intravenous immunoglobulin and plasma exchange are being investigated, but more evidence is needed.

In a small comparison, median time to independent walking was 27.5 days in the immunoglobulin group.

In the comparison group, median time to independent walking was 75.5 days.

Recovery times in the immunoglobulin group ranged from 15–127 days. In the comparison group, the range was 5–220 days. In another report involving two dogs, the dog receiving immunoglobulin recovered 12 days after the first visit. The dog treated without immunoglobulin recovered 34 days after the first visit.

Plasma exchange separates the liquid part of blood from its cells and replaces it with donor plasma. In one severe canine case, independent breathing returned 3 days after plasma exchange. However, the same dog was later euthanased because of tracheostomy complications. This single case could not establish whether improvement resulted from plasma exchange or continuing supportive care.

Plasma exchange may cause adverse circulatory or immune reactions. Citrate in donor plasma may lower blood calcium. Monitoring during the procedure includes ECG, blood pressure and breathing.

Prevention

There is no known way to prevent every case, as most dogs have no identifiable trigger. Avoiding raw chicken reduces exposure to a recognised risk factor. Raw pet food can contain Campylobacter. The microbiological risks of raw food are greater than those of heat-treated food.

Wash equipment used for raw food immediately after use in water above 70°C. Wash food and water bowls too, as bacteria survive on their surfaces. Wash your hands after handling raw food before preparing food for people.

Important for dog owners

Record the first day of weakness, progression from hindlegs forwards, bark changes, head control and ability to eat. Mention diet, previous diarrhoea, vaccinations and travel abroad too. Take a short video of movement without forcing your dog to stand.

Home care can start when symptoms are stable and your dog can eat and drink. Setbacks can occur even after initial improvement, so monitoring continues.

Before discharge, agree how to lift, support and help your dog with toileting. Ask for a practical demonstration of position changes, feeding posture and individual exercises. Record even small improvements separately: lifting the head and supported standing are different from independent walking.

Frequently asked questions

Can a paralysed dog recover?

Yes: most dogs begin improving within 3 weeks. Full recovery may take 2–6 months. However, severe symptoms and marked muscle wasting can leave permanent weakness. Breathing muscle weakness makes the situation more serious.

Is my dog in pain or losing sensation?

Pain perception usually remains in the acute form, even when a dog cannot move its legs. Some dogs are sensitive to touch on the trunk or limbs, even if weakness is otherwise the main sign. The vet may include pain relief in supportive care for this discomfort.

Do corticosteroids help nerve root inflammation?

Corticosteroids have not shown benefit in acute idiopathic polyradiculoneuritis. They may help some dogs with the chronic relapsing form. Chronic disease typically progresses slowly over months. Treatment is therefore not transferred from one form to another simply because the names are similar.

Is stiffening of a puppy's hindlegs the same disease?

Nerve root inflammation in puppies may be caused by Neospora or Toxoplasma protozoa. Symptoms can begin at 3–8 weeks of age. Severe stiffness with the hindlegs held extended may develop. This form needs antiprotozoal treatment, which works better when started early.

Can raw chicken be linked to the disease?

Raw chicken has been identified as a risk factor for acute disease. A possible link is an immune reaction triggered by Campylobacter. However, most affected dogs have no clearly identified triggering exposure. Diet history is therefore part of the investigation but does not replace a neurological examination.