Lens Luxation In The Miniature Bull Terrier

Lens Luxation mutation FOUND!!

September 1, 2009
University of Missouri, College of Veterinary Medicine

  A mutation responsible for the development of lens luxation in many breeds of dogs has been identified by a team of researchers led by Gary Johnson DVM PhD at the University of Missouri College of Veterinary Medicine. A DNA test for this mutation is expected to be available by late September 2009 through a partnership with OFA (Orthopedic Foundation for Animals).

Lens Luxation is an eye problem well known in many Terrier breeds, Chinese Cresteds , Australian Cattle Dogs, Tibetan Terriers, and other breeds. The lens is held in place in the eye by fibers known as zonules. If these zonules break or disintegrate, the lens can fall out of place, or luxate. When this happens it often requires immediate veterinary attention to remove the displaced lens. Lens luxation can cause secondary glaucoma, which also leads to pain, loss of vision, and sometimes loss of the entire eye.

Research at the University of Missouri has led to identification of a DNA mutation that predicts which dogs are at risk for developing lens luxation as they age. A simple DNA test will reveal if a dog is NORMAL (has 2 normal copies of the gene), a CARRIER (has one normal copy and one mutated copy of the gene) who will not develop lens luxation but could pass the mutation on to offspring, or AFFECTED/AT RISK (has 2 mutated copies of the gene). Wise use of this test gives breeders a tool to avoid producing individuals at risk of developing lens luxation, while still retaining many other desirable traits in their dogs.

Breeders and individual owners will be able to test their dogs using the testing kit that can be ordered online through the OFA website (www.OFFA.org). DNA is collected using a cheek swab, and the barcoded sample will be tested by the Animal Molecular Genetics Lab at the University of Missouri, with results reported directly to the owner by OFA. PLEASE NOTE: this test is not yet online at OFA, but should be available by the end of September 2009. This website will be updated with an announcement as soon as the test is online at OFA. 

Researchers collaborating on this project have agreed to:

• Share DNA samples, phenotype and genotype data

• Co-author manuscripts resulting from the research

• Place discoveries in the public domain

Currently the researchers included are

University of Missouri Gary Johnson DVM, PhD Elizabeth Giuliano DVM, MS, DACVO Kristina Narfstrom PhD Shahnawaz Khan PhD Liz Hansen

Animal Health Trust Matthew Binns PhD Cathryn Mellersh PhD

2.  The issue of heart disease in  Miniature Bull Terriers is primarily seen in the form of congenital heart disease.  The two forms commonly seen is Mitral Valve Dysplasia and Sub-aortic Stenosis. 

Heart disease can either be congenital (dog was born with it)  or acquired (a problem occurring later in life).

Mitral valve dysplasia presents as a "leaking" valve between the two chambers of the heart, the left atrium and left ventricle.  Usually the mitral valve does not shut completely which causes the blood that should be pumped entirely into the aorta to supply the body with oxygenated blood from the left ventricle; to leak back into the left atrium.  The result is a murmur.  It is called Mitral Regurgitation.  When the mitral valve is narrowed, it is difficult for the blood to leave the left atrium.  This is called Mitral Stenosis.  Dogs with this condition can be affected mildly or severely.  Most dogs can live active normal lives, but with age the condition can worsen and they can die of heart failure.

Sub-aortic Stenosis is the narrowing of the aorta, the major artery carrying the blood supply away from the heart.  The condition leads to pulmonary edema which results in left-sided heart failure.

There are several tests your veterinarian can perform to screen for these conditions, x-ray series of the chest, ECG or electrocardiography to measure the heart's electrical activity, and a cardiac ultrasound or echocardiography.  Many reputable breeders test their dogs with cardiac color Doppler ultrasound for very accurate diagnosis. 

We start Echo Color Heart Doppler testing our miniature bull terriers at the age of six months  and then again between the age of one year and 18 months.  All additional testing will be per Cardiologists recommendations.

Here at Cambria Miniature Bull Terriers we strive very hard to do a good breeding program, We do Echo Color Heart Dopplers on all our breeding parents.  We have done over thirty Dopplers with all different results.. One thing I can say about the Dopplers and the findings is...  over 75% of the dogs I have tested have had to some degree a Mitral Valve regurgitation.  Some of my dogs that have MV have been given a normal and some have been given an Equivocal (A congenital or acquired heart disorder cannot be definitively diagnosed or excluded.) Cambria has used both Normals and Equivocals in our breeding program.  Several of the progeny have been Echo Dopplered and the results have been comparable. 

Cambria takes every effort to make the best health decisions for our planned breeding program.  We are very honest and will devulge any and every known health problem that we are aware of in our pedigrees. 

Skin

4.  Skin Diseases

Some Miniature Bull Terriers, particularly white Miniature Bull Terriers, may have skin problems.  Some dogs respond well to dietary changes of a more natural-type foods or raw with few or no chemical additives.  Others may require allergy testing along with long-term treatment of antibiotics, food change and possible allergy injections. 

Do remember even though the parents of future puppies may have been tested for all of the above health related problems.  This does not guarantee that the animal will not later become afflicted with the maladies that we mentioned.

Breed Standard

General Appearance  

The head should be long, strong and deep, right to the end of the muzzle, but not coarse. The full face should be oval in outline and be filled completely up, giving the impression of fullness with a surface devoid of hollows or indentations, i.e., egg shaped. The profile should curve gently downwards from the top of the skull to the tip of the nose. The forehead should be flat across from ear to ear. The distance from the tip of the nose to the eyes should be perceptibly greater than that from the eyes to the top of the skull. The underjaw should be deep and well defined.

To achieve a keen, determined and intelligent expression, the eyes should be well sunken and as dark as possible with a piercing glint. They should be small, triangular and obliquely placed, set near together and high up on the dog's head. The ears should be small, thin and placed close together, capable of being held stiffly erect when they point upwards. The nose should be black, with well developed nostrils bent downwards at the tip. The lips should be clean and tight. The teeth should meet in either a level or scissor bite. In the scissor bite, the top teeth should fit in front of and closely against the lower teeth. The teeth should be sound, strong and perfectly regular.

Neck, Topline, Body

The hind legs should be parallel when viewed from behind. The thighs are very muscular with hocks well let down. The stifle joint is well bent with a well developed second thigh. The hind pasterns should be short and upright.

Feet - The feet are round and compact with well arched toes like a cat.

Coat - The coat should be short, flat and harsh to the touch with a fine gloss. The dog's skin should fit tightly.

Color - For white, pure white coat. Markings on head and skin pigmentation are not to be penalized. For colored, any color to predominate.

Gait - The dog shall move smoothly, covering the ground with free, easy strides. Fore and hind legs should move parallel to each other when viewed from in front or behind, with the forelegs reaching out well and the hind legs moving smoothly at the hip and flexing well at the stifle and hock. The dog should move compactly and in one piece but with a typical jaunty air that suggests agility and power.

Temperament

Thank you for taking the time to read about the Miniature Bull Terrier!