Medical Beat (3-16-10)

Post date: Mar 9, 2010 5:14:13 PM

Back to my real hobby, doggie medical research!

Progressive Retinal Atrophy: New Data

When I learned that Trevor had prcd-PRA in the fall of 2008, the conventional wisdom said that PRA was an inexorable disease whose course could not be changed in any way. You could find a few websites hinting at the possibility that antioxidants might slow progression. But there were no details. So like other PRA moms and dads who found themselves in a similar situation, I had to put together my own program and hope for the best.

Today, only 18 months later, the picture is entirely different. I have to admit that I'm amazed by how much things have evolved in such a short period of time. There is now compelling evidence that diet and supplements can in fact make a difference in the progression of retinal degeneration.

Here are some recent developments:

    • RetinaComplex. For most of 2009, the cornerstone of Trevor's regime was a human supplement called RetinaComplex (he is now getting OcuGLO instead, since it is the canine version of the same key ingredients). In September 2009, RetinaComplex completed its first year of clinical trials for retinitis pigmentosa, which is the human version of PRA. They have already seen positive results after first year of for RP (Sept. 2009). Excerpt from referenced article:

In the placebo group the Multi focal ERG readings taken at the beginning of the study showed a statistically significant difference to those taken at the end of the 12 month period. Patients receiving Retina Complex showed no statistically significant difference between the two sets of data. This confirms that there is a SLOWER progression of disease in the treated subjects compared with those getting only placebo.

    • Saffron. Dr. Silvia Bisti has been researching the use of saffron to slow the progression of retinal degeneration. She started with rodent trials, and she recently completed her first human trial for macular degeneration (January 2010). The trial showed strikingly positive results. Here is the University of Sydney press release. Here is another article on the trial. Excerpt:

Professor Jonathon Stone of The Vision Centre, an Australian research organisation, said, "The outcome of this experiment was remarkable – significant improvement in vision after several weeks of taking saffron in pill form, which reversed when the patients were taken off it.

"This is very encouraging for a non-invasive way to treat certain important eye diseases."

The effects of green tea catechins in reducing harmful oxidative stress in the eye lasted for up to 20 hours, the study says.

    • OcuGLO. One of the most exciting developments of the past 6 months has been the commercial release of OcuGLO, the first human grade eye supplement designed for dogs. One of its primary uses is in dogs with retinal degeneration, where the hope is that it will slow progression of the disease. The data is anecdotal so far, but very promising.

Of course it's hard to say what any of this means. None of these things constitutes a cure. Even if these supplements do delay progression by a "statistically significant" amount, does that make a quantifiable difference from the patient's perspective? No one knows. On the other hand, it seems obvious that preserving your dog's eyesight for as long as possible is a good thing. There is also the chance that a real treatment will become available (i.e., gene therapy) if you can preserve viable photoreceptor cells for long enough.

Masticatory Muscle Myositis

In July 2009, my lab Rowan was diagnosed with masticatory muscle myositis (negative on titer test, diagnosis was made through muscle biopsy). We have been treating him with prednisone. This past week (March 10, 2010) we tapered him all the way back to a schedule of 10mg/5mg on alternating days. If this goes well, in a month we'll taper back further to 10mg every other day. Fingers crossed that Rowan doesn't relapse as we taper his dosage back. It's been a long road. If you've ever had a dog on a high dose of prednisone, you know what I mean!

Here is a summary of his prednisone treatment:

August 8, 2009: Started 20mg/day.

August 21, 2009: 40mg/day.

September 9, 2009: 60mg/day.

September 30, 2009: 50mg/day.

October 14, 2009: 40mg/day.

October 28, 2009: 30mg/day.

November 17, 2009: 20mg/day.

December 18, 2009: 15mg/day.

January 8, 2010: 10mg/day.

March 10, 2010: Switched to a month of alternating days of 10mg/5mg. Will continue for a month, then switch to 10mg every other day.

How is Rowan Doing?

Rowan is doing well. The frustrating thing about prednisone is that its side effects are so severe that once you start giving it, it's hard to distinguish the pred side effects from the disease itself. But in summary:

    • Rowan's MMM is unilateral--left side only--so he has never shown the jaw paralysis that is the primary symptom of the disease.
    • In late August/early September 2009, he started exhibiting jaw problems. His jaw was never closed or paralyzed, but he was working it a lot and we could hear clicking. That's when we dramatically increased his dosage.
    • Once we increased his dosage, the jaw symptoms rapidly diminished, and they have not returned to date.
    • He subsequently developed a dent on the right side of his head too. This could be the progression of the disease, but it is more likely a side effect of the pred. He also started to show a lot of muscle wasting in his spine and hindquarters--definitely the pred.
    • As we've tapered his dose, his muscle tone has improved. However, his head is as dented on both sides as ever. Also, his hair still hasn't grown back from when he was shaved for his various tests back in July/August. He still looks like Frankendog, poor guy.
    • There is very little data on long term outcomes with MMM. You have to stay vigilant since there is always the possibility of a recurrence. I found a few links that hint at how the disease may play out long term:
    • Small study: http://www.marvistavet.com/html/body_masticatory_myositis.html
    • Golden Retriever forum where several people share their experiences with MMM. It's anecdotal and filled with all kinds of misinformation, but it yields an interesting composite portrait of the disease.