What_is_MegaEsophagus
It is thought that bitches should NOT BE USED  for further breeding IF they have produced  any offspring with either singular or multiple defect, defects which could prevent their offspring from living a normal, healthy life without major surgical or medical intervention becoming necessary.
Current Studies
Rhodesian Ridgeback


White German Shepherd Dog


Addison's  Disease  Study
Bearded Collie, Great Dane, Leonberger, Portuguese Water Dog, Standard Poodle  or  West Highland White Terrier.  Please visit the  U.C. Davis
Canine Genetic Analysis Project
to learn how you  can become involved.

Golden Retriever
Cricopharyngeal Dysphagia
University of Pennsylvania

The Canine Genetics Laboratory at Clemson University has funding from the Canine Health Foundation to use the newly available canine SNP aray to identify genes having a role in megaesophagus, pancreatic insufficiency, and degenerative myelopathy.

To Read the Full Article: Click Here

~ ~ ~


Heritability by John Pollack, Ph.D., Cornell University

Genetic Testing: A Guide for Breeders by Mary Whiteley, Ph.D.


The Nature of Genetic Disease
by John Armstrong
Canine Genetic Primer
Dis-'ease':  Vital Force & Genetics

Prioritizing Genetic Defects
(Megaesophagus is listed as a 'severe' trait in the Hierarchy of Disagreeableness of a Genetic Trait)
"We need to quit whispering about defects, and gossiping about defects, and instead set up a sound program that allows the standard selection procedures to go on so that we breed good dogs and avoid major defects."
~  Dr. George A. Padgett, DVM
Samples needed from megaE  GSDs!


The Canine Genetics Laboratory at Clemson University has funding from the Canine Health Foundation to use the newly available canine SNP aray to identify genes having a role in megaesophagus, pancreatic insufficiency, and degenerative myelopathy.

To Read the Full Article: Click Here
"Once you choose hope and knowledge, anything is possible."
The term heritable should be distinguished from the term congenital (birth defects), which may or may not be heritable.

Adjective: inheritable  (in'heritubul)
That which can be inherited "inheritable traits such as eye colour."

Adjective: genetic (ju'netik)
Tending to occur among members of a family, usually by heredity
- familial, hereditary, inherited, transmitted,         transmissible.
By definition:
"Increased susceptibility to a particular disease due to the presence of one or more gene mutations, and/or a combination of alleles (haplotype), not necessarily abnormal, that is associated with an increased risk for the disease, and/or a family history that indicates an increased risk for the disease ." 
The disease has been reported as being genetic in the breed involved.

The disease has been reported to be genetic in other breeds.

The disease has been reported as being genetic in other species.

The disease follows family lines, and it occurs in multiple generations of a given line."
Inherited GI Disorders
Although breed predispositions are recognized for many  gastrointestinal disorders, in most cases the scientific studies to  establish the inheritance have yet to be carried out.





Twenty disease states are listed as inherited gastrointestinal disorders.

Megaesophagus is one of the twenty listed.                          ~  Merck Vet. Manual
As excerpted from The Control of Canine Genetic Disease
by Dr. Padgett

The criteria for including a disease as genetic includes any or all of the following:
"These criteria may be considered to be very loose or minimal as requirements for categorizing a disease as genetic and may have resulted in a few errors among the diseases included. However, the goal of this book is to prevent genetic diseases in breeding kennels as well as within breeds. If there are errors here, they are on the side of preventing the spread of a disease by recognizing the disorder as being genetic or very likely to be genetic.

Megaesophagus is confirmed to be inherited.
Genetic inheritance may not be limited to the following breeds:

Akita   .   .   .   .   .   .   .   .   .   .   .   .
Alaskan  Malamute 
Australian Shepherd
Beagle
Bedlington Terrier
Boston Terrier   .   .   .   .   .   .   .                    
Boxer                       
Bouvier des Flandres    .   .   .                                                       
Burnese Mountains Dogs
Chinese Shar-Pei     .   .   .   .   .   .                  
Cocker Spaniel                          
Dalmation     .   .   .   .   .   .   .   .   .                    

Doberman                                    
English Bulldog   .   .   .   .   .   .    
English Setter ~                
FlatCoated Retriever
French Bulldog
Fox Terrier     .   .   .   .   .   .   .   .                    
German Shepherd Dog     
Golden Retriever    .   .   .   .   .   .                 
      <-------     <------- Gordon Setter
Great Dane    .   .   .   .   .   .   .   .                    
Greyhound                           
Irish Setter .   .   .   .   .   .   .   .   .          
Irish Water Spaniel~           

Irish Wolfhound    
Irish Red & White Setter  ~              
Italian Greyhound    .   .   .   .   .                  
Jack Russel Terrier          
Labrador Retriever  .   .   .   .   .   .           
                                                         
Lakeland Terrier
Leonberger
Mastiff   .   .   .   .   .   .   .   .   .   .   .                    
Miniature Pinscher
Miniature Schnauzer .   .   .   .   .    
Newfoundland              
Poodle    
Pug
Portuguese Water Dog
Rhodesian Ridgeback  .   .   .   .        
Rottweiler                                  
                                                      
Scottish Terrier   .   .   .   .   .   .   .
Shetland Sheepdog
Springer Spaniel      
Skye Terrier
Duck Tolling Retriever
West Highland White Terrier
White Shepherd     .   .   .   . . 
*Wirehaired Fox Terrier                       
** Highly variable expression
~ List update, Dr. Jean Dodds
* As per the Canine Inherited Disorders Database:
                "It is advised that affected dogs of these breeds not be bred. In other breeds in which inheritance is unknown,  it is safest to avoid breeding affected dogs, their parents and siblings".

Major Contributing Source:
Breed Predisposition to Disease and Congenital Conditions

The No. 1 breed experiencing MG with associated ME
Autosomal Recessive-  (LP & ACP complex that can include ME)

Esoph. achalasia & PRAA
Esophageal dilation


Congenital Laryngeal Paralysis, Esoph./pharyngeal muscle
        degeneration and dysphagia, Megaesophagus

Congenital Megaesophagus
Esoph. achalasia & PRAA
LP & ACP complex that often includes ME
Suspected Auto. Recessive - LP & Vascular compression/Esophagus





Esoph. achalasia & PRAA , Congenital Myasthenia gravis
* * (Simple autosomal recessive), Myasthenia Gravis
Megaesophagus, Myasthenia gravis, Laryngeal paralysis
      <-------     <------- Gordon Setter
Autosomal Recessive
(Verify autosomal dominant)
Congenital idiopathic megaesophagus, Gastric dilatation/volvulus


GDV & Mega-E

PRAA, Esoph.Stenosis. PRAA is being studied; Mega-E is not.
Congenital Megaesophagus & Myasthenia gravis, Cushings
"Appears to be genetic in Labs; mode of inheritance unknown"  
                                                              Also, Laryngeal paralysis


Dilated esophagus. Can be inherited.

* Autosomal dominant Congenital idiopathic megaesophagus
Congenital idiopathic megaesophagus
See Poodle Health Registry


Believed to be simple recessive
Eosinophilic gastroenteritis/enteritis/enterocolitis
        Gastrointestinal eosinophilic granuloma
Study shows Scotties to be the 3rd  highest at risk for  MG - ME
Megaesophagus
Megaesophagus
Autosomal recessive Megaesophagus

Undetermined < 6 months * MegaE (Esoph.Achalasia – vomiting)
List of breeds
having incidence of Megaesophagus
& closeley related conditions
via known familial predisposition:
Identifying and Controlling Defective Genes
Knowing How is the First Step  in Tackling the Problem
by Jerold S. Bell, DVM
Steps to Eliminate Carriers:

1.   Not repeat the breeding
2.   Not use the sire/dam again
3.   Test the offspring and not breed from carriers


4.   Exclude littermates of those affected
5.   Not breed to close relatives of those affected.
Please Note:  A genetic marker test is not yet available.
Increasing Genetic Disease
Dr. Jerold S. Bell, D.V.M.
Clinical Assoc. Prof. Dept. of Clinical Sciences
Tufts University School of Veterinary Medicine

"The problem with increasing genetic disease and the perception of decreased genetic diversity in dog breeds, is from the popular sire syndrome. If popular sires carry deleterious recessive genes, then these will be spread into the gene pool through their descendants. This is called the founders effect. I have seen genetic disorders become fixed and increase in frequency in breeds through the founders effect. This is not a problem only for breeds with small gene pools. I have seen it in some of the larger AKC registered breeds." (Visit the Canine Diversity Project on the web for more details.) "Most of my recommendations on disorders without known modes of inheritance, or without tests for carriers, involve knowledge of affected or carrier dogs in the depth and breadth of the pedigree. ... most people are not talking about the affected dogs they produced."
~   ~   ~   ~   ~
~Dr. Bell is Dir. of the Clinical Vet. Gen. Course for the Tufts University School of Vet. Medicine & National Project Admin. for numerous genetic disease control programs of purebred dogs. He performs genetic counseling through Veterinary Genetic Counseling and practices small animal medicine in Ct. He and his wife breed Gordon Setters.
RISK RATIO ASSESSMENT
Autosomal Recessive Trait*
Risk of being a carrier if related to an affected dog

                                                                      Degree of          Minimum
Relationship              Relationship      Carrier Risk

Parent, Progeny

Full Brother / Sister       

Grandparents, Aunts, Uncles,         
   Half-brothers or sisters, Grandchildren         

Niece, Nephew        

Great-grandparent, First Cousins,             
  Half-aunts and uncles, Great-grandchildren   

Great-great-grandparents,         
  1st Cousin once removed, 2nd Cousins         

Great-great-great grandparent,         
  1st Cousin twice removed, 3rd Cousins   

*This chart is used for Autosomal Recessive Traits as well as Polygenic Traits – 
the risk for the Polygenic Trait will be "at least" this percentage.
1

1

2
2

2

2
2

3
3

-
-

100%

60.0%

50.0%
50.0%

33.3%

25.0%
25.0%

12.5%
12.5%

6.25%
6.25%

The Canine
Genetic Heritage Project
Preserving the genetic
past for future generations
"In summary, a brilliant book for bringing  genetic diseases out of the closet."
~ A Reader
by
George A. Padgett
"If people tell you their dogs have never produced a defect, their dogs have only produced one litter, they don't follow up on their puppies, or what is most likely the case, they are being less than truthful."
~  Dr. George A. Padgett, DVM