Degenerative Peripheral Neuropathy (DPN)

Unfortunately I have had this occur in several  of the dogs that I have bred. Onset is normally 8-9 years of age and you normally get 2-3 years of progression before they are unable to get up by themselves and their quality of life must be questioned. Here is all that I could find written by Vets on this disease. I have spent in excess of $30000 trying to get a diagnosis and hopefully a treatment on this disease with no success РI have worked with Vet Scientists, Vet Neurologists, multiple Vet practices and basically there is no treatment and there is no genetic test for this as multiple genes come into play so it is not a matter of a simple Mendelian ratio to eliminate this.

I thought long and hard about continuing with my lines once I realised I had an issue (8-9 yrs is well past breeding age and it wasn’t until the second dog had it that I started to see an issue) and I thought about ditching them altogether and starting again. Only after discussion with several Vets that I decided to continue and try to breed out this issue – which I still do not know if I have – by using judicious outcrosses from long lived sound lines. Some may say I should have started again but if I had, who knows what other disease I may have ended up with trying to eradicate that may or may not have been worse than this. Yes I believe I know which lines it comes from but due to legal issues I will not publicly post this – you are more than welcome to email me should you wish to know more.

The classic form of inflammatory neuropathy in the dog is a progressive weakness, which generally starts in the hindlegs, not associated with sensory or mental deficits. The onset may be insidious and progression slow, or signs may develop suddenly. The results of peripheral nerve testing are often variable.

Neuropathy means a disease of, or damage to nerves. When it occurs outside of the brain or spinal cord, it is called a peripheral neuropathy. When particularized to dogs, polyneuropathy is a collection of peripheral nerve disorders that are often breed-specific.

The job of the peripheral nervous system (PNS), is to carry information from the central nervous system, the brain, and spinal cord, to the rest of the body. While sensory nerves relay messages about touch, smell and taste, motor nerves serve to help the brain control the muscles. Autonomic nerves are central to the body as they control heart rate, breathing and digestion. Nerve damage substantially impacts the communication between the PNS and the entire body.

Peripheral neuropathies are neurological diseases or disorders which cause the reduction of motor function in the peripheral nerves. Peripheral nerves are located outside the brain and spinal cord.  Peripheral nerves form a network of nerves, which are a link between the brain and spinal cord to communicate with the body.

This network of nerves is responsible for coordination, digestion and physical responses. When the peripheral nerves are damaged they are not able to properly transmit. There can be many causes for the condition including neoplasia, inherited disease, diabetes, and toxin exposure. In the Staffordshire Bull Terrier we have found it to be caused by bony changes to T5 & T6 which is viewable on xray from approx 7-8 years of age.

Symptoms may vary depending on the underlying condition and the severity of the disorder:

  • Muscle tremors
  • Atrophy of the muscles
  • Weak reflexes
  • Lameness – dragging of toes front and / or rear
  • Abnormal gait – wide stepping in the rear
  • Unable to climb stairs
  • Tires easily
  • Lack of coordination
  • Weight gain
  • Increased thirst

Polyneuropathy is a nerve disorder that affects multiple peripheral nerves. Unlike the central nervous system, which has the vertebrae of the spine, and the bone of the skull to protect it, the peripheral nerves are more exposed to the elements that enter into the body and come into contact with the body, so they are more susceptible to physical injury and toxic damage. They are spread over the entire body, and are responsible for conscious, coordinated movement (somatic), for automatic physical responses (autonomic), and for the movement of the digestive system (enteric).

Myelin, the white, fatty, lipid material that acts as an insulator coat (also called a sheath) for some nerve fibers, can be lost through a process called demyelination, a condition that causes the myelin to deteriorate, resulting in electrical signals in the nerves being lost, and impairing function. Or, there may be axonal degeneration with secondary demyelination. Axonal degeneration occurs when the actual nerve fibers deteriorate within the myelin sheath.

Peripheral neural or muscular disease can occasionally be confused with orthopaedic disease. While the distinguishing characteristics of these two categories of disease can usually be observed during the physical examination, diagnosis is not always a simple matter. The hallmark of neural and muscular diseases is disuse of the flaccid type: sore limbs are carried; denervated limbs are dragged. However, peripheral soft tissue disease is often incomplete, leading to weakness and ataxia that are sometimes difficult to distinguish from gait abnormalities due to pain from orthopaedic problems. It is the purpose of this chapter to discuss the major peripheral nerve, muscular, and neuromuscular diseases in the dog, many of which might be confused with orthopaedic disease.

Inflammatory neuropathies are most often generalized and predominantly motor in type, but they may be localized and they may be predominantly sensory* or mixed in their functional effects. The classic form of inflammatory neuropathy in the dog is a progressive weakness, which generally starts in the hindlegs, not associated with sensory or mental deficits. The onset may be insidious and progression slow, or signs may develop suddenly. The results of peripheral nerve testing are often variable. In severe cases, complete motor nerve block may occur, making motor nerve conduction velocity (MNCV) determination impossible.

Tests that might be beneficial and that are often performed when inflammatory neuropathies are suspected include spinal fluid analysis and peripheral nerve biopsy. Unfortunately, the results of these tests are often inconclusive. Cummings and deLahunta reported an increased protein content in cerebrospinal fluid (CSF) in dogs with paralysis, while others report normal protein levels. Nerve biopsies are often normal in the face of severe disease, presumably because the inflammation is either patchy in its distribution or located in the ventral roots and not in areas of the peripheral nerve from which biopsy specimens can be easily obtained.

Prognosis and treatment of inflammatory neuropathies also present problems for which there are no simple solutions. As in humans, the leading cause of death in patients with these diseases is pneumonia secondary to respiratory insufficiency. The debilitation produced by the disease can be long lasting as well as profound, and the level of support and nursing care required to maintain such animals may be Herculean. There is no hard rule about the duration of illness. A logical mode of therapy would seem to include the use of immunosuppressive levels of corticosteroids, but such treatment may not be advisable because corticosteroids may hasten the advent of pulmonary complications. My preference is to use high levels of corticosteroids for a brief period-2 to 3 days- and if they prove to be beneficial as judged by neurologic evaluation, they are continued as needed. If the trial corticosteroid regimen produces no improvement, the drugs are stopped, and the clinician is left with simply trying to maintain the animal.

Currently, there is no treatment for these conditions. Though top researchers and veterinary colleges have devoted decades to the study of canine polyneuropathy, there are still more questions than answers.

On a personal note I did find with Jitt that maintaining back leg exercises in coordination helped slow the progress of this disease, unfortunately she did not live long enough for us to fully test this theory.

Litter 2 – affected – Maddy
Litter 7 – affected – Murtle, Grosby
Litter 8 – affected – Angel, Scooby
Litter 10 – affected – Daisy, Rosie
Litter 11 – affected – Oprah
Litter 12 – affected – Nougat
Litter 13 – affected – Jitty