Report on Ocular Melanosis Project

Simon Petersen-Jones & Lexi Mentzer
Michigan State University
Dept of Small Animal Clinical Sciences
D-208 Veterinary Medical Center
East Lansing, MI 48864-1314
Tel: (for Dr. P-J and Lexi Mentzer) 517-353-3278

Samples received:

DNA Samples: Thus far, we have 204 DNA samples (blood) from Cairn Terriers, of which 96 are from dogs affected with Ocular Melanosis, and the remainder are from relatives of dogs with Ocular Melanosis (OM). We have pedigree information on 240 dogs, and have linked many of them together to better analyze the mode of inheritance of the disease.

Enucleated Eyes: Since January we have received 2 additional enucleated eyes.

Gene mapping project

We are sending 94 samples from Cairn terriers within our extended pedigree of Cairns with ocular melanosis for genotyping. The reason that 94 samples are being sent is that the assay is done using microplates that hold 94 samples. We have to ensure that DNA quality and amount in each of those 94 samples is very similar. We are just finishing off diluting the samples to the same concentration and checking that the DNA in those samples can be amplified before sending them off.

Histological analysis

Lexi Mentzer spent two weeks with a veterinary ocular pathologist at University of Wisconsin going through all their archived material searching for more eyes from Cairns with ocular melanosis. They identified 45 Cairn eyes with ocular melanosis. This enabled them to compare the disease process between different dogs and attempt to rank the severity of each dog in a histological way, which we hope will benefit other veterinarians with their diagnosis of this disorder. We have also obtained additional slides from all these cases that we can stain with special stains to further define what the cell type is that is proliferating in the affected dogs.

We have had parts of affected and normal control eyes processed for electron microscopy and are in the process of examining the semithin-sections to choose the best areas to process for electron microscopy.

We have processed more eyes for immunohistochemistry which will also help us identify the cell type involved in ocular melanosis. Additional antibodies have been purchased and once the appropriate dilutions and staining protocol has been established in the lab we will use these to stain sections from our affected dogs.

Culture of abnormal cells from ocular melanosis

Lexi has established a collaboration with a researcher experienced in culturing cells. The reagents we will need for culturing the iris cells are ordered and a suitable protocol established. The first step will be for Lexi to learn this technique and to culture normal iris cells. Once this has been achieved we will then be ready to try and culture cells from an ocular melanosis affected eye. We will then need to wait until an eye becomes available. It is important that the eye is handled in a special way so we will need to contact the veterinarian involved to make sure that they are willing to help us.

What we need:

  1. We always need DNA samples (blood) from affected and related Cairns, accompanied by pedigrees and details of eye examinations.
  2. We need enucleated (removed) eyes from Cairns with ocular melanosis. It is important that we are contacted before they are removed so that we can ensure that the eye is handled in an appropriate manner for the part of the project we intend to use the eye for. See reference information above [...] for Lexi Mentzer.