Saved from the sidelines: Conservative management of intervertebral disk disease

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Saved from the sidelines: Conservative management of intervertebral disk disease

Score a touchdown with veterinary clients by getting affected dogs back safely on all fours with less monetary investment.
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Apr 19, 2017

"Put me in coach." (Shutterstock)

While CVC expert and educator Theresa Pancotto, DVM, MS, DACVIM (neurology), CCRP, thinks intervertebral disk disease (IVDD) is a primarily a surgical disease in most cases, sometimes—as we all know—the money just isn’t there. Fortunately, grades 1 and 2 IVDD can be treated successfully with conservative management. Read on for how to formulate a winning game plan.

Quick team huddle: Even though grades 1 and 2 IVDD respond favorably to medical management, Dr. Pancotto thinks those cases are still ultimately surgical candidates, and the earlier that pet is treated, the better the prognosis. Be sure to counsel owners on the option of surgery even for cases with comparably mild signs since even ambulatory dogs can have extruded disk material that will never resolve and cause chronic discomfort that goes unrecognized by owners. This is particularly true for dogs with cervical IVDD.

Choose your players wisely

When it comes to conservative management, the location, severity and duration of IVDD all influence whether or not treatment will be successful. Dogs with cervical disease do not respond as well to conservative therapy as do dogs with injury in the T3-L3 area, Dr. Pancotto says. Grades 1 and 2 IVDD on the modified Frankel scale are the best candidates for medical therapy.

First, let’s get everyone on the same page1:

Grade 1: Pain only, no proprioceptive deficits

Grade 2: Ambulatory with or without pain, ataxia, proprioceptive deficits

Grade 3: Fecal and urinary incontinence, nonambulatory tetra/paraparesis

Grade 4: Tetra/paraplegia, incontinence

Grade 5: Loss of deep pain

Chondrodystrophic dogs are the No. 1 dog Dr. Pancotto sees for grade 1 IVDD, especially dachshunds, beagles, cocker spaniels and basset hounds. In large breeds, Labrador retrievers, Weimaraners and German shepherds have a higher incidence of type 1 versus type 2 disease. The patients are typically young (3 to 5 years old) and present with acute pain and some degree of ataxia in either two or four legs. They can progress quickly or stay stagnant over several weeks to months.

The grade of disease is the most important prognostic indicator for whether your patient will respond to conservative therapy. Dr. Pancotto says the prognosis of patients that have lost deep pain is about 50:50 with surgery and essentially 0% without surgery. With increasing severity, patients will have less of a chance of responding to conservative therapy and, as the grade worsens, Dr. Pancotto says the success rate of conservative management goes down 10% to 15%.

The success rate for surgical management of type I IVDD is > 95% and 60% to 80% with type 2 IVDD, depending on ambulatory status.1

On initial assessment, Dr. Pancotto cautions that on physical exam you cannot discriminate between patients that have spinal shock, which is an acute and typically self-limiting functional change in the spinal cord, versus those that have myelomalacia, which is ascending hemorrhage and necrosis that occurs secondary to severe intervertebral disk extrusion. If a patient with a T3-L3 spinal cord injury presents with loss of deep pain, a high panniculus and decreased reflexes in the pelvic limb instead of upper motor neuron signs, then be suspicious of myelomalacia or spinal shock. Spinal shock patients will get better, myelomalacia patients will not. Dr. Pancotto recommends counseling the owner on the possibility of both for up to five days after presentation.

Plot your Xs and Os

The location of the lesion is key. Cranial cervical myelopathy patients frequently present with pain and normal neurologic function. Caudal cervical myelopathy typically presents as thoracic limb weakness with both ataxia and weakness in the pelvic limbs. These signs are commonly seen in older Dobermans with disk-associated Wobbler’s syndrome (DAWS). Reflexes in the thoracic limbs are inaccurate approximately 30% of the time.2 In these cases, Dr. Pancotto recommends assessing the muscle tone of the limb. Dogs with caudal cervical lesions tend to have more “floppy” limbs, and dogs with cranial cervical lesions tend to have increased extensor tone.

The most common location for type 1 nuclear extrusion is T3-L3; within this segment, T10-L2 segments are predisposed, notes Dr. Pancotto, causing upper motor neuron signs in the pelvic limbs. Lesions at L5-S1 cause pain, paraparesis and pelvic limb lower motor neuron signs.

Plain radiographs cannot definitively diagnose a disk problem, Dr. Pancotto says, but they can rule out other conditions (e.g. discospondylitis, atlantoaxial luxation, osteomyelitis, neoplasia), and may have radiographic evidence of narrowed disk spaces and degenerative changes supportive of IVDD.

Tag your treatment tactics

Goals of medical management include controlling pain, preventing further deterioration, and preventing complications, such as decubital ulcers, urinary tract infections and self-mutilation.

Grades 1 and 2

When it comes to medical management, cage rest is the most important—and the most ignored therapy by your client, especially as the dog starts to feel better. Dr. Pancotto’s trick for getting clients to grasp the concept of absolute cage rest is to tell them that for two weeks, the dogs have to be in “prison.” No exceptions. That means in the kennel at all times and carried outside for bathroom breaks. They don’t get time to sniff around. If they don’t pee, they go back in the house and you can try again later. The reason Dr. Pancotto requires two weeks is if there is a tear in the annulus, then two weeks are required to heal that tear and prevent additional nuclear material from being extruded or, in layman’s terms, “squished out.”

After the first two weeks, Dr. Pancotto requires two additional weeks of restricted activity with specific guidelines regarding physical rehabilitation for a total of four weeks of rest. If you give the client specific instructions, she says, then they are more likely to follow your instructions and continue the cage rest while they are doing the specific exercises. Dr. Pancotto starts with three- to five-minute walks on a leash and specific physical rehabilitation exercises such as a sit-to-stand, standing and weight-shifting exercises, and passive range of motion.

If the patient presents with moderate pain, Dr. Pancotto recommends giving an injectable opioid and carprofen in the hospital. Butorphanol is not enough, she says—use oxymorphone, hydromorphone, methadone or morphine.

Pain may be managed orally with tramadol (5 to 8 mg/kg) and an anti-inflammatory. Acetaminophen with codeine can be accurately dosed in large breeds but should be compounded for small breeds. Codeine may also be helpful.

With grade 2, Dr. Pancotto will add in gabapentin or methocarbamol, but she thinks methocarbamol only helps dogs with visible muscle spasms. Gabapentin can be useful long term in dogs that you think may be predisposed to chronic pain.

If the patient is severely painful, Dr. Pancotto recommends hospitalizing the dog and giving intermittent opioid injections (every four to six hours) or a poly-pharmacy constant-rate infusion (CRI) such as morphine/lidocaine/ketamine with loading doses. If the client is unable to elect hospitalization because of financial constraints but you feel like this patient would really benefit from injectable pain medication, you can also suggest that the client bring the pet back for injections or apply a fentanyl patch.

The first recheck should be within 48 hours to ensure that the patient is responding to the medication, Dr. Pancotto says. If the patient is the same, then you can add in additional medication, acupuncture and heat and ice packing, or consider referral. If the patient is worse than on initial presentation, then the odds of success by continuing what you are doing are not good. If the patient is improved, continue as previously directed. Dr. Pancotto medicates these patients for a full two weeks and then tapers medications one by one.

The second recheck should be at the two-week mark, before the client reinstitutes controlled physical activity, and the final recheck should be scheduled around eight weeks.

Grade 3

 

Treatment for grade 3 is the same in regards to cage rest and pain control, but now you will need to counsel the owners to monitor their pets’ bladder function. Dr. Pancotto finds that bladder management impacts quality of life and is usually the leading cause of euthanasia in these patients.

If there are signs of overflow incontinence, then prazosin or phenoxybenzamine should be prescribed to relax the urethral sphincter and aid in bladder expression. Dr. Pancotto recommends giving the medication 30 minutes before expressing the bladder. If the abdominal wall is very tense, you can prescribe diazepam or methocarbamol to reduce abdominal wall tone as needed. Dr. Pancotto advises against prescribing bethanechol in dogs with upper motor neuron signs (tight urethral sphincter) because of the risk of bladder rupture.

Dr. Pancotto recommends hospitalization for grade 3 dogs, if only to closely monitor them for signs of deterioration in bladder or neurologic function that may go undetected by the owner. Furthermore, manual bladder expression is cheap, but painful. If you have a grade 3 dog that is painful and needs bladder expression, Dr. Pancotto recommends hospitalization with intermittent or indwelling urinary catheterization to avoid exacerbating pain during manual bladder expression.

If clients cannot afford to hospitalize, even if the dog is urinating on its own, teach them how to express the bladder and to monitor whether the dog is emptying its bladder completely twice daily. Also discuss what the signs of overflow incontinence are. Husbandry issues, such as rotating the dog’s position every four to six hours, keeping bedding clean and dry, and providing appropriate padding to prevent decubital ulcers are also important points of education for your client.

When you recheck grade 3 patients at 48 hours and two weeks, check them for signs of urine scald, decubital ulcers or self-mutilation. The penis and the toes are most likely areas that are self-mutilated. Dr. Pancotto recommends checking a urine culture at the two-week visit for grade 3 dogs.

For dogs with urinary incontinence that does not resolve, Dr. Pancotto performs monthly urine cultures for three months. If the results are consecutively negative, then culture every six to 12 months.

Grades 4 and 5

Even if these dogs respond and regain deep pain or movement, they are likely to have permanent neurologic deficits without surgical intervention. These patients are managed the same way as grade 3 patients, and it is necessary to counsel the owners on the potential for the need for permanent bladder management and the possible need for a cart. Grade 5 patients have a very poor prognosis for return to function, even if deep pain returns.

Dr. Pancotto recommends hospitalizing these patients. If they are not hospitalized, she recommends a daily neurologic exam to monitor for any progression of disease.

What’s the deal with corticosteroids? Dr. Pancotto says glucocorticoid administration can complicate the care of recumbent and incontinent patients because of PU/PD side effects and a predisposition to decubital ulcers. Corticosteroids can also mask inflammatory conditions or undiagnosed lymphoma as well as contribute to complications with bleeding. If you do give corticosteroids, dosages should be kept between 0.5 and 1 mg/kg (prednisone equivalent). Dexamethasone is contraindicated even at an appropriate dose because of complications associated with GI bleeding and hemorrhage within and around the spinal cord.3

The use of corticosteroids in spinal cord disease is controversial because in studies, there has not been a statistical difference between dogs that received a single dose of methylprednisolone versus those that have not.4,5 In people, a single high dose is correlated with an increase in fine motor function, which has not translated to functional outcomes in dogs.4,5 A few high-dose protocols are described, but no strong evidence that they work. A single high dose of 30 mg/kg over an hour, followed by a CRI of a lower dose over 24 hours can be used. Note: Single high-dose corticosteroid administration is with methylprednisolone sodium succinate, never dexamethasone, says Dr. Pancotto.

Time to bring in the special teams?

Dr. Pancotto likes acupuncture in her postoperative patients for pain relief and neuromodulation. She also recommends heat for areas where dogs are likely to have compensatory pain, such as the shoulders and upper back. Dogs with thoracolumbar disease tend to shift their weight onto their thoracic limbs and shoulders, so warm-packing their necks may be more beneficial than warm-packing their backs.

Dr. Pancotto theorizes that therapeutic laser is reasonable for IVDD but may be contraindicated in cases with degenerative myelopathy. Because degenerative myelopathy is a gain-of-function superoxide dismutase 1 mutation, it results in increased antioxidant activity. Laser, a stimulatory treatment, could worsen this activity. It is known to be contraindicated in the face of neoplasia or active hemorrhage for similar reasons. Dr. Pancotto recommends against chiropractic in dogs with acute disk disease.

Small steps to get your patients back in the game

Dr. Pancotto recommends starting physical rehabilitation, including leash walks and massage, after the two weeks of strict rest and then more active physical rehabilitation after four weeks, with a gradual return to full function by eight weeks. In general, avoid all high-impact activities during recovery and counsel your clients to invest in ramps for the couch and the bed.

References

1. Sharp NJ, Wheeler SJ. Small animal spinal disorders, diagnosis and surgery. 2nd ed. Philadelphia: Elsevier, 2005.

2. Forterre F, Konar M, Tomek A, et al. Accuracy of the withdrawal reflex for localization of the site of cervical disk herniation in dogs: 35 cases (2004-2007). J Am Vet Med Assoc 2008;232:559-563.

3. Levine JM, Levine GJ, Boozer L, et al. Adverse effects and outcome associated with dexamethasone administration in dogs with acute thoracolumbar intervertebral disk herniation: 161 cases (2000-2006). J Am Vet Med Assoc 2008;232:411-417.

4. Olby NJ, Muguet-Chanoit AC, Lim JH, et al. A placebo-controlled, prospective, randomized clinical trial of polyethylene glycol and methylprednisolone sodium succinate in dogs with intervertebral disk herniation. J Vet Intern Med 2016;30:206-214.

5. Bush WW, Tiches DM, Kamprad C, et al. Functional outcome following hemilaminectomy without methylprednisolone sodium succinate for acute thoracolumbar disk disease in 51 non-ambulatory dogs. J Vet Emerg Crit Care 2007;17:72-76.

Editor's note: The sentences above concerning laser therapy to treat IVDD have been changed from the original to clarify the possible contraindications associated with the use of this therapeutic modality.