Category: fovea

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Seizures

Seizures are a bummer. Any owner who has a seizure dog can relate to the stress of going out of town because of a complicated medication regimen, the fear of the seizure dog getting out with the pack while no one is home, the concern for possible injury with cluster seizures, and the balance of keeping a few extra pounds on the dog in case they have a severe cluster.

Seizures can be caused my brain tumors, autoimmune disease, and infections. However, the majority of seizures are idiopathic meaning that no one knows why they happen.

Darla has idiopathic epilepsy with severe clusters. Meaning once she has one seizure she is going to have another and another. She recently spent a few days in the ICU to get her medications adjusted and so far she is doing better. She currently takes two medications—levetiracetam and phenobarbital. We also have a “cluster buster” pill that she takes once she has a seizure. After discharge from the ICU she was receiving medication four times a day, it was a full time job to make sure she was getting what she needed.

Due to the complexity of home care for some seizure dog I wanted to highlight what we have done to simplify things.

  1. Get a pill organizer—I used to question if I had given her medication or not this helped.
  2. The seizure dog needs an identifiable food bowl—the dog that needs the medication, CBD, or supplement needs to get it! I recommend stainless steel bowls like these
  3. If possible switch to extended release medication—our four times a day dosing was reduced to two times per day (remember these extended release tablets cannot be halved or they become immediate release).
  4. Medication coupons—we have a 50% off coupon for one of her medications through GoodRx.
  5. Take the kid gloves off—After Darla has been sick I want to keep her calm and in the house, not fun for Darla. Make sure that your seizure dog gets to do doggy things. A slow easy walk always seems to lift Darla’s spirit after she’s been sick—remember to take it easy, muscles are very sore after seizures.
  6. Feed your seizure dog! I tend to keep a few extra pounds on Darla and after a seizure I feed her a larger portion. She burned a huge amount of calories and needs fuel.

Life is different with a seizure dog but is still very good! These ideas are simple and make life easier for us and hopefully more enjoyable for Darla.

Living her best life now!

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The Fovea has it

Science really gets me excited.  What is most exciting is when something new is discovered.  This could be a new treatment, new technology, or revisiting of a previously thought notion or idea.

Eyes are one of the coolest organs in the body.  They are windows to the brain and some would say to the soul.  In humans the vital sign of the eye is visual acuity—you know, when you have to cover one eye and read the eye chart.  20/20 vision means that you see the same as a normal eye would see at 20 feet.  20/100 vision means that you see what a normal eye would see at 100 feet.  As you might imagine it’s much more difficult to test the visual acuity of a dog’s eye—they can’t tell us what they see.  Due to this, some scientists believe that the visual acuity of the dog has been underestimated.

We know that dogs see differently than humans do.  For many years we have known that dogs can see much better in low light than us; they have rapid vision that allows them to detect rapid changes in the light, and, due to the placement of their eyes in their skulls, they have wider visual fields than we do (Miller & Murphy, 1995).

All of these qualities aid the dog, a predator, in its ability to hunt.  However, the acuity at which the dog can focus was thought to be diminished, as the dog is known to lack a fovea (Miller & Murphy, 1995).  Fovea centralis (fovea) is a structure in the human eye.  The fovea is a depression within the retina that contains a large number of densely packed cones type cells that are responsible for visual acuity (Beltran et al., 2014).

For years scientists have felt that the dog’s visual streak was responsible for their visual acuity.  The visual streak is an area in the retina with increased amounts of photosensitive retinal ganglionic cells and cone cells (Miller & Murphy, 1995).  However, in 2014 things changed.

In 2014 the canine retina was evaluated with in vivo (in life) and ex vivo (in death) imaging (Beltran et al., 2014).  The researchers found an area in the retina very similar to a non-human primate fovea, which they deemed the area centralis.  This area was tiny but full of densely packed cone cells (Beltran et al., 2014).  This area was not a fovea-like depression but was very similar from a histologic standpoint to what is seen in the center of the human fovea, the foveola (Beltran et al., 2014).

You may be asking why is she so excited about this? This information is incredibly important.  This indicates that a dog’s visual acuity is actually better than previously thought.  The visual acuity of a dog was thought to be about 20/50 (Miller & Murphy, 1995).  Based on the findings in this study, the visual acuity of the dog would be between 20/24 and 20/13 (Beltran et al., 2014).  That means that dogs could be able to see at 20 feet what a normal eye would see at 13 feet!

The canine eye is an important structure for multiple reasons.  For our Greyhounds the eye is important for racing, lure coursing, coursing, hunting, fetching, running through agility obstacles, and their everyday lives.  Just imagine having better than perfect vision and then adding a wider visual field, the ability to detect rapid changes in light, and the ability to see in low light—I would be overwhelmed with that much stimuli going through my brain all the time!  Dogs are complex animals and the more we learn about them the more I amazed by all they do!

Beltran, W. A., Cideciyan, A. V., Guziewicz, K. E., Iwabe, S., Swider, M., Scott, E. M., Aguirre, G. D. (2014). Canine retina has a primate fovea-like bouquet of cone photoreceptors which is affected by inherited macular degenerations. PLoS One, 9(3), e90390. doi:10.1371/journal.pone.0090390
Miller, P. E., & Murphy, C. J. (1995). Vision in dogs. J Am Vet Med Assoc, 207(12), 1623-1634.