All this and a jam donut
The types of disc disease.
Disc disease. We’ve all told owners that it’s a ‘slipped disc’ but how true is that? It’s more along the lines of a disc herniation – where the disc isn’t in its correct anatomic location. This can be further subdivided into disc extrusion or protrusion.
Extrusion is found in Hansen type 1 disc disease, and can be thought of as a jam donut squishing out. Primarily found in chondrodystrophic dogs, the dehydrated nucleus can be chronic or acute. Often seen as ‘Fluffy was painful last night and now can’t move her legs’.
Protrusion is found in Hansen type 2 disease, where both the inner and outer layers of the disc protrude into the spinal canal. I suppose you can think of this more like a yorkshire pud bulging out of a tin. No, I don’t know where all this food comparison comes from but it sure does make it easier to visualise. Protrusion, type 2 disc disease, usually presents in animals 6-8 years old. The longer the disc sits in the cord, the more likely atrophy is.
In both of these cases, the compression leads to a hypoxic environment which then leads to free radicals. Sort of like a bruise inside the spinal cord. Compression can cause secondary effects like neurogenic shock, biochemical changes, and electrolyte changes.
In chondrodystrophic dogs, the dehydration of the discs and associated degeneration starts as early as 6 months old.
At 1 year, 75% of discs are dehydrated and at 2yrs approximately 90% are dehydrated.
This doesn’t necessarily mean that there are clinical signs though.
The Wild Card
A potential third type of disc disease?
A third type of disc disease has been found, although it doesn’t sound as ‘Hansen type 3’ because Hansen didn’t discover it, it’s still important to know about it! The stereotypical patient in type three disc disease is a large dog with an acute onset non-painful disease. It’s a high velocity, low volume extrusion of the nucleus into the spinal column. There is some trauma, some cord contusion but theres no compression or disc degeneration. The good news? If there’s still good pain perception, the patients have an 80% chance of recovering with supportive care.
On a scale of 1-10, how much does it hurt?
The grading scheme.
I’m a huge proponent for grading schemes. It helps clinicians and nurses monitor the changes over time, and provides a simple way to portray information between note-takers. The grading scheme for disc disease is as follows…
What are my chances, doc?
Prognosis and future predictions.
Any dog that’s paralysed and cannot feel their digits is at risk of progressive myelomalacia. This is usually delayed in onset, approximately after the first 72 hours. Profound pain and hyperthermia (temperature >40*C) can be found. You can also notice an ascension of the cutaneous trunci reflex, loss of anal tone and continence, and even progression to respiratory arrest.
The chances of recover depends greatly on the grade. After a certain grade, the choice between medical and surgical management can result in a drastically different outcome. See below the chances of recovery depending on medical or surgical treatment.
In this webinar review, I won’t be going over the surgical management as the webinar didn’t cover it. That being said, since the webinar mentioned steroids and I wanted to cover that as Dr. Simon Platt had some great points.
Steroids. Yay or Nay?
Therapeutics for Disc Disease.
There’s a lot of controversy about whether or not to use steroids in IVDD. It turns out that ‘solu-medrol’ used to be part of a therapy protocol, was proven not to be effective. Some have misinterpreted this as no steroids at all in disc disease.
We have to return to our first principles. There is inflammation present in these cases and it’s important to control that .
You can do this with NSAIDs or low-dose steroids (that is, 0.5mg/kg) for a short course. Combine this with strict cage rest for 4-6 weeks, gabapentin, opioids, and muscle relaxants (such as diazepam and methocarbamol) to supplement healing. This protocol is best with sub-acute cases.
Supportive care is quite hands-on, and requires quite a lot of monitoring. Monitor for decubital ulcers, urine scald, aspiration pneumonia. You can assist your patient by turning them every four hours, using non-slip mats and waterbeds, and cushioning them as much as possible.
As the muscles in the hindlimb are often not being used – or are not being used enough – physiotherapy and hydrotherapy can be useful to support regeneration of the muscles.
Summary of Disc Disease
This webinar came at the best time for me, I had just treated a pup with high grade IVDD and wanted to make sure that I had given them the best chance that I could. Dr. Simon Platt presents the information in this webinar in a really succinct and clear way that’s easily understandable. Although this may not be an appropriate webinar for neurology specialists, it’s definitely at the right level for general practitioners and for people who want to brush up on the latest in the IVDD sphere. The webinar contains a lot more information and some great underpinning understanding of the disease, so I’d recommend you give it a watch here.
If you’d like to have a bit of a chat about the webinar or just look at fun cases and chat with other vets, you can find our social group, VetTalk.
I hope you enjoyed, and as always happy watching!