DEAFNESS
Bull Terriers along will other breeds carry the deafness gene It can affect both coloured and white Bull Terriers. Dogs can be totally deaf (Bilateral
deafness )or can have hearing in one ear ( Unitaleral deafness)
Inside the dogs ear.
Their are four parts to a dogs ear, the ear flap, the ear canal , the middle ear and the inner ear. The ear flap is made of cartilage, muscle and skin which
you can see on the dogs head this flap captures sound waves and allows them to travel to the ear drum (tympana membrane) which than vibrates. The
middle ear is the area behind the ear drum which contains the tympana cavity. This is where the auditory tube, the tympana nerve, the vestibulal window
and the cochlea along with other parts are. Also within the middle ear are three small bones ( the smallest bone in the body) the malleus. The incus and
the stapes. These bones transmit the air vibrations from the ear drum and tympanic cavity to the inner ear. The inner ear is where the air vibations are
converted into nerve impulses, which when reaching the brain results in hearing. It is a labyrinth of fluid filled sacs, which are contained within an
osseous lebyrinth. The osseous parts of the inner ear are a shell shaped cochlea. This cochlea winds around a hollow core,containing the cochlea
nerve. Within the cochlea are around 10,000hair cells which respond to the air vibrations and stimulates the nerve cells to send messages to the brain,
these hair cells are what the ear uses to changes to electrical signals that the brain then recognises as sound.
What causes deafness
The cause of deafness is not yet fully understood, however it is believed to be caused by the loss of blood supply to the cochlea and thus causing the
degeneration of the hair cells contained in the cochlea. Without these hair cells their is no way the ear can change air vibrations into electrical signals
which the brain recognises as sound. Inheritance is not known at this time though DNA testing is being conducted to try and find the gene which
produces deafness, as two fully hearing parents can produce deaf or partial deaf puppies while in the same litter you can have full hearing puppies.
BAER testing
BAER (Brainstem Auditory Evoked Response) The only way to be certain that you dog can hear properly from both ears. In this test a computer is used
to record the electrical activity of the brains response to sound stimulation. A sound stimuli, a series of clicks, is passed though headphones placed over
the dogs ears whilst recording electrodes are placed on the dogs neck just behind the head. Puppies can be tested from 6 weeks of age and will require
a light sedation to keep them still. BAER testing is required only one in a puppies life and a certificate will show the results
HEART DISEASE
What is congenital heart disease?
A heart condition due to structural defect within the heart present at birth. Cardiac defects in Bull terriers include leaky valves or narrowed valves. Both
of these general defects will result in a heart murmur - an abnormal heart sound which is detected with a stethoscope by a veterinary cardiologist or a
veterinary surgeon.
Overall view of the normal anatomy of the heart:
The heart has four chambers. The right atrium (RA) collects venous blood from the body, and it passes through the tricuspid valve to the right ventricle
(RV) The right ventricle pumps the venous blood, though the pulmonic valve, into the pulmonary artery and so into the lungs, where the blood is
oxygenated. The blood returns to the heart, into the left atrium(LA) Blood passes though the open mitral valve into the main pumping chamber of the
heart, the left ventricle (LV) When this pumps, the mitral valve closes and blood is ejected out via the open aortic valve into the aorta which divides to
every artery to all the organs of the body.
Mitril Dysplasia:
Mitral dysplasia is a malformation of the mitral valve apparatus. The normal mitral valve apparatus consists of two valve cusps. These are anchored by
chordae tendinae to two papillary muscles in the left ventricle. The papillary muscles and the cow the valve to close when the ventricle contracts, but
restrain the valve so it does not flap back into the left atrium. The closed valve should be a tight seal, allowing no blood into the left atrium.
With mitral Dysplasia in Bull Terriers, the mitral valve apparatus is deformed. The valve cusps become thickened and nodular. The papillary muscles are
very large and thick and only very short, thickened and chordae tendinae attach the papillary muscles to the valve leaflets.
The most common consequence of mitral dysplasia is a leaky mitral valve. During ventricular contraction (systole) instead of the mitral valve sealing
shut it allows a jet of blood to pass backwards into the left atrium, as well as pumping blood forward in the normal direction, into the aorta. This leak is
known as mitral regurgitation The turbulent jet of blood flow due to mitral regurgitation can be heard with a stethoscope it is a systolic heart murmur,
which is most intense over the mitral valve area of the dogs chest. Loud murmurs can radiate to other parts of the dogs chest as well.
Occasionally, the mitral valve in mitral dysplasia can be narrowed as well, called mitral stenosis. It is difficult for the left atrium to empty into the left
ventricle. Pressures can build up in the left atrium. The left atrium may become greatly enlarged.
Consequences of mitral dysplasia:
Dogs with mitral dysplasia will have a heart murmur. If the valve is only slightly leaky, the murmur is only soft and the dog may not be affected at all.
Where there is severe mitral regurgitation, a large volume of blood moves back and forwards across the mitral valve, overloading the left side of the
heart. The left atrium and left ventricle can became very large indeed. Changes occur gradually, but eventually, pressures build up in the left atrium,
and blood dams back into the lungs, and comes out of the circulation into the normally air filled spaces of the lungs - this is called pulmonary oedema.
Once this happens, the dog is in congestive heart failure. Dogs with pulmonary oedema will be breathless and will cough. With mitral stenosis also
present, left atrial enlargement in massive and pulmonary oedema rapidly develops. Where the left atrium becomes very stretched, irregular or chaotic
heart rhythms can develop, such as atrial fibrillation. The rhythm will worsen the symptoms of dogs with congestive heart failure, especially if they have
mitral stenosis.
Dogs with severe mitral dysplasia have poor heart output into their circulation they may faint on exertion or excitement or stress (syncope) as their
brains can become short of oxygen.
Aortic Stenosis
The aortic valve is positioned between the left ventricle and the aorta. It opens as the left ventricle contracts, allowing the left ventricle to eject blood into
the aorta. It normally offers no restriction to blood flow.
With aortic stenosis, the aortic valve itself or a fibrous band beneath the valve (Subaortic stenosis) restricts the outflow to blood from the left ventricle.
The left ventricle has to work hard just to eject blood, and the heart muscle becomes thickened to compensate. Blood ejecting past the obstruction to
outflow is very fast and turbulent. This turbulent flow causes a heart murmur which can be detected with a stethoscope over the aortic valve area of the
chest wall. The louder the murmur, the more severe the aortic stenosis and the faster and more turbulent the blood flow passing the obstruction. This
turbulent blood flow can affect the walls of the aorta, and it can stretch, called post-stenotic dilation. As the left ventricle muscle thickens, it exceeds the
coronary artery blood supply to it. This means that areas of the heart can be deprived of oxygen. The muscle becomes irritable and may cause
abnormal beats (called ventricular premature complexes or VPCs)
Diagnosis of congenital heart disease
As explained above, congenital heart disease is manifested by a heart murmur, which is detected by a veterinary surgeon or a veterinary cardiologist by
careful clinical examination, including auscultation, with a stethoscope. Because Bull Terriers are not easy dogs to auscultate, sometimes the dogs own
veterinary surgeon may not have detected the murmur.
Heart murmurs show that there is turbulent blood flow in the heart, which is abnormal. Murmurs are graded out of 6 - where Grade 6 is the loudest
murmur which can be detected. Grade 1 murmurs are the most quiet and difficult to detect. A very quiet room, a good quality stethoscope and a quiet,
calm dog who is not panting are required before the murmur is detected.
Mode of inheritance
This is not yet been proven, However the fact it is common in Bull Terriers and in certain family lines, there is significant clustering of heart disease, it
probably is inherited. Careful family history, cardiac examinations is necessary before breeding and any animals found with heart murmurs of any grade
should be removed from a breeding programme.
KIDNEY DISEASE
What the Kidneys do
The Kidneys primary function is to regulate the plasma and tissue fluid in the body by the formation of urine, quite simply the kidneys are filtering
harmful toxins from the body though the urine. In the process of urine formation the kidneys also regulate:
1. The volume of blood plasma and thus significantly to the regulation of blood pressure,
2. The concentration of waste products in the blood,
3. The concentration of electrolytes and other ions in the plasma and
4. The pH of plasma
So if the kidneys do not work correctly it can have a devastating effect on the whole body.
WHAT IS POLYCYSTIC KIDNEY DISEASE
Polycystic kidney disease (PKD) is an inherited disease characterized by the growth of numerous cysts filled with fluid in the kidneys. PKD cysts can
slowly replace much of the mass of kidneys, reducing kidney function and leading to kidney failure.
There is no cure for Polycystic kidney disease some diets may slow down the speed of the kidney degeneration however the final result is death from
kidney failure.
Mode of inheritance
Polycystic kidney disease is a autosomal dominant hereditary disease, which means that one or both of the parents have the gene and will pass it on to
up to 90% of the litter.The disorder can be readily eliminated by avoiding the breeding of affected individuals.
Testing for Polycystic kidney disease
Testing for Polycystic kidney disease is by renal ultrasound, which demonstrates the presence of fluid -filled cysts in the cortices and medullae of the
kidney
WHAT IS HEREDITARY NEPHRITIS:
Hereditary Nephritis is inherited in an autosomal dominant manner and is characterised by glomerulopathy, progressive renal atrophy and renal failure
at varying ages.
Mode of inheritance .
Hereditary Nephritis is an autosomal hereditary disease which may be inherited from either parent, is reqiured to produce the trait. The parent with the
dominant trait will pass the affected gene to approximately half the offspring, and the trait will be apparent in both the parent and the affected progeny.
The disorder can be readily eliminated by avoiding the breeding of affected individuals.
Testing for Hereditary Nephritis:
Testing is by the collection of a midstream urine sample ( the first of the day ) in a sterile pot and sent to the lab for Protein:creatinine ratio analysis. The
UPC will be returned within 24 hours and should be 0.3 or under. UPC of over 0.3 does not mean the dog has hereditary Nephritis and tests should be
preformed to rule out renal tract infection.