Enhance Detection, Diagnosis and Treatment of Canine Lymphoma

A Collaborative Study by Veterinary Oncologists, Pathologists, and Diagnostic Laboratories to Enhance Detection, Diagnosis and Treatment of Canine Lymphoma

To enhance detection, diagnosis and treatment of lymphoma. Therefore altering cost of treatment according to the type of tumor (as in humans) and increase survival rate.

Results

Canine lymphoma is the neoplasm most often treated by chemotherapy, yet there is little data relating response to therapy of its different subtypes. This study is based on 1043 cases of canine biopsies where lymphoma was the clinical diagnosis. All cases were phenotyped by staining with CD3 and CD79alpha. Cases with histiocytic proliferation were stained with CD18 and 12 cases were examined by PCR to verify clonality. Survival data was obtained on 466 dogs where time cause of death or time of last follow-up when known to be alive was available; additional covariate information included phenotype, stage and grade of lymphoma, and treatment protocol. One hundred dogs were still alive at last follow-up. Because of the many subtypes of B and T-cell lymphoma the cases were grouped into 7 diagnostic categories that included: 1.benign hyperplasia, 2. low grade B-cell, 3. high grade B and T-cell, 4. Low grade T-cell, 5. centroblastic large B-cell of all mitotic grades, 6. immunoblastic large B-cell of all mitotic grades and 7. high grade peripheral T-cell. Grouping was determined by histologic grade (based on mitotic rate/400X field, with low grade 0-5, intermediate 6-10 and high grade >10) and clinical grade for survival function estimation. No impact on survival was found with size or breed of dog and sex.

All diagnostic categories of indolent or low grade type had low mitotic rates, while those with clinically high grades were high. The diagnostic category with the most cases was large B-cell lymphoma. This category, with a broad range of mitotic rates, was also evaluated for survival based on clinical stage of tumor. Treatments for high, intermediate and low grade lymphomas were divided into two groups based on the presence or absence of hydoxy-daunorubicin to evaluate survival analysis using the most populous group (5) for reference. Patients with T-zone lymphoma had the longest median survival (223 days) while the shortest median survival was in patients with peripheral T-cell subtype (162 days). The reference group of centroblastic large B-cell was sub-divided by clinical stage, median survival of 328 with low stage, 223 days with intermediate stage, and 202 days with advanced stage. Animals with T zone lymphoma were probably diagnosed in later stages of disease because of the lack of signs associated with progression. As with human lymphomas, a histological diagnosis with immunophenotyping is a minimal requirement for diagnosis of a specific subtype. Lymphoma can be diagnosed by cytologic examination, but a specific subtype cannot be determined by this method or flow cytometry.

Co-sponsored with the AKC Canine Health Foundation, Grant Number: 00768

RESEARCHERS

Ted Valli, DVM
University of Illinois

Mapping Genes Associated with Canine Hemangiosarcoma

Hemangiosarcoma (HSA), a malignant tumor of vascular endothelial cells, is a significant health concern in dogs, with an incidence of ~2% of all tumors. A national health survey of Golden Retriever reported that neoplasia accounted for >60% of all reported deaths and HAS was the most common malignant tumor affecting >15% of Golden Retrievers. A particularly high disease incidence of hemangiosarcoma in Golden Retriever suggests a genetic susceptibility.

The purpose of this study is to identify the mutations causing the increased risk for hemangiosarcoma in Golden Retriever. To do this, we have proposed to compare the genotypes of dogs diagnosed with HSA with healthy older dogs using a statistical analysis.

Results

To date, we have collected 125 blood samples from Golden Retrievers diagnosed with HSA and more than 400 healthy Golden Retrievers over 8 years old. We have identified six regions in chromosomes associated with HSA and are have narrowed these to precise regions (a few hundred thousand base). We now need to find the precise mutations that cause the disease and link them to functionality. In the long term, this work should allow the development of specific genetic tests for carriers of HSA. Ultimately, understanding of the disease biology, which will lead to identification of target genes for prevention, early detection and novel treatments of this malignancy.

Co-sponsored with the AKC Canine Health Foundation, Grant Number: 00593A

RESEARCHERS

Kerstin Lindblad-Toh, PhD
Broad Institute at MA

Identifying Genes Regulating Addison’s Disease in the Portuguese Water Dog

Addison’s disease, or primary adrenocortical insufficiency, is characterized by destruction of the adrenal cortex, resulting in the inability to produce cortisone when stimulated with the hormone ACTH. In Portuguese Water Dogs (PWDs), this disease occurs with a frequency of 1-2 percent, and is a heritable autoimmune disease of low penetrance, caused by several interacting genes.

Using both new and existing data, we propose to identify regions of the PWD genome that contain genes regulating the frequency of Addison’s disease. Within those large regions we propose to identify the specific DNA sequence variants that are associated with Addison’s.

Results

To date we have obtained DNA from about 90 Addisonian PWDs, as well as a number of unaffected PWDs, for which no family history of Addison’s is reported. We have already identified two genomic regions, on canine chromosomes 12 and 37, that appear to be associated with the disease. To identify candidate genes, we will make selections using the newly available canine genome sequence, as well as the more detailed human genome sequence. Once affected gene disease frequency is identified, our long term hope is that prognostic tests can be developed that will aid breeders in selecting the most genetically compatible dogs for future.

Co-sponsored with the AKC Canine Health Foundation, Grant Number: 00589B

RESEARCHERS

Elaine Ostrander, PhD
National Human Genome Research Institute

Mapping Refinement of Quantitative Trait Loci for Canine Hip Dysplasia

Hip dysplasia is one of the most common inherited traits in dogs with an extremely high incidence in some large breeds. It is caused by mutations in multiple genes. In previous studies, investigators discovered the genetic markers that point to the chromosomal regions that harbor the genes that contribute to hip dysplasia.

In this study, they will narrow down these regions through additional genetic evaluation. By narrowing the regions that harbor hip dysplasia genes across breeds, they hope to discover the contributing mutations and use that information to design genetic tests that can be used to prevent the propagation of dysplastic dogs.

Results

Researchers identified the first mutation associated with canine hip dysplasia in Labrador retrievers. This mutation could be used in conjunction with a panel of genetic markers to identify susceptible dogs. The team also learned that there is no single gene identified for hip dysplasia in dogs. This study pointed to several other genes that contribute to the disease, and researchers believe they will discover these genes through the process they have developed.

Based on their findings, the researchers hypothesize that identifying dogs that are resistant to hip dysplasia will involve a panel of genetic markers that may be breed specific. Breeders could then use these panels in conjunction with breeding values to genetically screen puppies before the mutations themselves can be identified. This project lead to the discovery of the first gene associated with canine hip dysplasia.

Co-sponsored with the Morris Animal Foundation, Grant Number: D04CA-135

RESEARCHERS

Rory J. Todhunter, BVSc, PhD
Cornell University

Canine Lymphoma

MicroRNAs (miRNAs) are small non-coding RNAs that have been implicated in humans as having a fundamental role in cancer initiation and progression. Canine diffuse large B cell lymphoma (DLBCL) represents one of the most frequently encountered canine neoplasms. We hypothesized that canine DLBCL possess a unique miRNA expression signature and that miRNA dysregulation contributes to chemoresistance and prognosis.

Results

In this study we confirmed that miRNAs in the dog are very similar to those in humans, i.e. are highly evolutionarily conserved, and that different miRNA analysis technologies that are applied to human cancers can be similarly applied to canine cancers. Furthermore, miRNA expression in healthy normal tissues is similar in dogs and humans. When we used “next generation” sequencing of canine DLBCL tumor samples to determine their miRNA expression profiles we identified a miRNA that was significantly overexpressed in chemotherapy naïve tumors compared to chemotherapy relapse tumors from the same patients. Significantly, this was a miRNA with known importance in human cancers. Additionally, we identified a unique miRNA expression signature (multiple coordinately expressed miRNAs) that was associated with overall survival in dogs with DLBCL and treated with a standard chemotherapy regimen. These findings provide insights into mechanisms of lymphomagenesis and potential targets for future therapies.

Co-sponsored with the AKC Canine Health Foundation, Grant Number: 00632

RESEARCHERS

W. C. Kisseberth, DVM, PhD, Dip. ACVIM (Oncology)
Ohio State University

Gene Expression Profiling of Relapsed Lymphoma in Dogs

Lymphoma is one of the most common cancers in dogs. Breeds with a high incidence include Boxers, Golden Retrievers, and German Shepherds. It is also one of the most treatable cancers – more than 90 percent of dogs treated with chemotherapy go into remission. Unfortunately, most dogs relapse and eventually die from the disease.

Results

The investigators compared gene-expression patterns of tumors before and after chemotherapy to determine changes that took place in the dogs that relapsed. They identified important candidate genes and different subtypes of lymphoma that will help in the development of new cancer treatments. These candidate genes must now be independently validated in another set of patient samples but have already contributed greatly to the understanding of genes associated with relapse and potential new therapeutic targets.

Co-sponsored with the Morris Animal Foundation, Grant Number: D03CA-132

RESEARCHERS

W. C. Kisseberth, DVM, PhD
Dip. ACVIM (Oncology)
Ohio State University

Establishing a Genetic Linkage Between Addison’s Disease and DNA Markers

Statistical evaluation of the dogs’ pedigrees suggests a single locus of large Addison’s disease is a late onset disorder caused by deterioration of the adrenal gland cortex. Although Addison’s disease occurs in the general canine population, some breeds show a greater prevalence as noted by owners and breeders: Bearded Collies, Standard Poodles, Leonbergers, Portuguese Water Dogs, and West Highland White Terriers.

Results

We have demonstrated that for Standard Poodles and Bearded Collies, Addison’s disease is highly heritable. Effect significantly influences the expression of Addison’s in the Standard Poodle and that this locus acts as an autosomal recessive. Similar findings characterize Addison’s for the Bearded Collie although the level of significance is less robust.

The specific objectives of this grant are to expand our pedigree, phenotypic, and DNA databases for all possible Bearded Collies, Standard Poodles, Leonbergers, Portguese Water Dogs and West Highland White Terriers as related to Addison’s disease and to continue our genome scan of the DNA to identify a genetic marker linked to the single locus suggested by the pedigree analyses.

Co-sponsored with the AKC Canine Health Foundation, Grant Number: 00225

RESEARCHERS

Anita M. Oberbauer, PhD
University of California, Davis

Characterizing the Inheritance of Addison’s Disease and Linked DNA Markers

Addison’s disease is a late onset disorder caused by the deterioration of the adrenal gland. Addison’s occurs in the domestic dog at approximately 0.1 percent, with some breeds showing a greater prevalence. Notably, the Bearded Collie, the West Highland White Terrier, the Standard Poodle, the Portuguese Water Dog, and the Leonberger are considered to have unacceptable rates of Addison’s disease. Breeders have noted a familial tendency of Addison’s disease suggesting a genetic basis to the disorder.

Results

Our laboratory has determined that Addison’s is highly heritable in Bearded Collies. Further, although Addison’s is not fully governed by a single locus in the Bearded Collie, it does appear to be regulated by a single gene of large effect.

The specific objectives of this study are to develop a genetic marker associated with an Addison’s locus in the Bearded Collie; such a genetic marker will provide a useful tool to aid breeders in making health-based breeding decisions. The second objective is to determine if Addison’s disease in the Standard Poodle, West Highland White Terrier, Portuguese Water Dog and Leonberger also has a genetic basis and if so, whether there is a common genetic defect across all these breeds.

Co-sponsored with the AKC Canine Health Foundation, Grant Number: 0002226

RESEARCHERS

Anita M. Oberbauer, PhD
University of California at Davis