Unfortunately,
the Boxer is susceptible to several potential health
problems, below is a short list of those conditions
most common in the boxer breed.
• Major concerns: cardiomyopathy,
SAS, CHD
• Minor concerns: gastric torsion,
tumors, intervertebral disc degeneration,
corneal erosion, colitis
• Life span: 8 - 10 years
• Note: sensitive to heat and anesthesia.
See info below on Acepromazine |
Hip Dysplasia
Hip dysplasia is the number one cause of hind limb lameness
in dogs and results in an arthritic condition of the
hip joint which is initially caused by a laxity (looseness)
in the hip joint itself. This joint is a ball and socket
joint in which the head of the thigh bone (femur) fits
into a cup-like depression (acetabulum) in the pelvis.
The laxity is associated with the tissues which surround
and hold the joint in place, that is, the tendons, ligaments,
connective tissue, and muscle, and this laxity leads
to bony abnormalities of the ball and socket. While
the laxity of the joint is not thought to change much
with time, the presence of joint instability causes
abnomal wear and tear on the cartilage lining of the
joint with subsequent development of arthritis as the
dog ages.
Indeed, the Orthopedic Foundation for
Animals (OFA) believes that there is little change in
the test for dysplasia after 4 months of age; however,
they require testing at two years of age or older for
certification purposes, to err on the side of caution.Clinical
signs can be extremely variable -- from no symptoms
to severe lameness. Severity of arthritic changes on
radiographs (X-rays) does not necessarily correlate
with degree of lameness.
Diagnosis is made from radiographs of
the hip joint (from the pelvis to the kneecap) and does
require sedation or anesthesia. Positioning of the dog
is critical for proper evaluation. The radiographs are
evaluated by veterinary radiologists specially trained
for this task. The dogs are graded as excellent, good,
fair, borderline, or mildly, moderately, or severely
dysplastic.
A newer method of evaluating hip joint
laxity called PennHIP has been developed at the University
of Pennsylvania School of Veterinary Medicine. This
involves a different method of positioning the dog and
uses a distraction device that is fitted to the dog
during the procedure. Three views are taken, including
a compression view, a distraction view and the standard
(OFA) extended view. From the radiographs, the dog is
assigned a DI or distraction index from 0-1.0, with
values of 0.3 or below considered NOT at high risk for
developing dysplasia. The dog is also ranked with other
members of its breed in a percentile. (A dog ranking
in the 80th percentile has 20% of its breed showing
tighter hips.) This test can be performed at 16 weeks
of age, but the originators of the method admit greater
reliability if the test is performed later (at one year).
Hip dysplasia is thought to be genetically
determined in part, but the mode of inheritance has
not been established, since multiple genes and environmental
factors such as nutrition and rapid growth may play
a role in its development.
While some have questioned the frequency
and severity of hip dysplasia in the boxer, many owners
are now testing their dogs. The OFA currently reports
the boxer as 67th in incidence of dysplasia (among breeds
where over 100 dogs have been tested) with 2.9% of boxers
testing excellent and 11.3% dysplasitic. The OFA Web
Site at www.offa.org,
or the PennHip website at www.vet.upenn.edu.html
are sources of additional information. This and other
information is best discussed with your own veterinarian.
Thyroid Disease in
Boxers
Thyroid disease in the boxer occurs primarily as hypothyroidism,
or impaired thyroid gland function with low thyroid
hormone levels. It often develops slowly over several
months or years. The animal's body, for as yet unknown
reasons, forms antibodies against its own thyroid gland
resulting in partial or complete destruction of the
gland and the subsequent inability to produce adequate
thyroid hormone.
Many breeds, including the boxer, seem
to be genetically predisposed to hypothyroidism. Affected
animals may be listless, develop coarse haircoats, have
significant hair loss, gain weight, experience infertility
and/or fetal resorption or show neurologic problems.
In some cases, abnormal test results may preceed the
clinically apparent stage of the disease. A simple thyroid
test (T4) obtained from your veterinarian is often inaccurate
and can give falsely low readings in normal dogs with
concurrent non-thyroid illness and normal values when
thyroid disease is in the early stages.
More definitive testing may be obtained
by performing a panel of tests which include Total T4,
TGAA (thyroglobulin autoantibodies), cTSH (canine thyroid
stimulating hormone), so-called "free T4 by equilibrium
dialysis," and sometimes T3 and free T3. This panel
is currently not available from all diagnostic laboratories
and must be sent to one of several reference laboratories
by your veterinarian. Repeat testing may be recommended
at regular intervals, because the disease can be slow
to develop and current test results may not predict
future abnormalities. Your veterinarian may not feel
the need for these additional tests if the dog has no
clinical signs of hypothyroidism, but owners who suspect
their animals of being hypothyroid despite normal values
on simple T4 tests and/or those who suspect an hereditary
condition due to knowledge of affected relatives may
wish to pursue more definitive testing as a screening
mechanism in consultation with their veterinarian.
Boxer Cardiomyopathy
One of the most common causes of sudden/unexpected death
in boxers, both young and old, is a condition thought
to be inherited and characterized by abnormal heart
rhythms involving the ventricles (the main blood pumping
chambers) of the heart. This condition can cause varying
degrees of disability and occasionally results in congestive
heart failure. Current research has determined that
the disease is the result of an electrical conduction
disturbance which causes the heart to contract too early,
thus producing an extra, ineffective beat, the so called
Premature Ventricular Contraction (PVC). While many
dog breeds may have a few of these PVC's, the boxer
seems to be prone to having more of these premature
beats. When large numbers of these PVC's occur together,
the heart muscle cannot produce a normal, effective
contraction, which results in a lack of blood flow to
vital organs including the brain and the heart itself.
This can cause the animal to experience a seizure-like
or fainting episode (syncope). A prolonged sequence
of PVC's can lead to complete cardiac arrest unless
the heart resumes a normal pattern of contractions.
Less commonly, the lack of adequate contractions may
cause the heart to fail and the dog's heart may dilate,
causing congestive heart failure with symptoms such
as shortness of breath, exercise intolerance, abdominal
swelling, coughing and symptoms similar to those occurring
in humans with heart failure. This is known as dilated
cardiomyopathy —a less frequent condition in the
boxer than the more commonly seen electrical conduction
defect.
The definitive test for this disease would
be a DNA test for the abnormal gene. This research is
currently underway at Ohio State University, but research
of this type can take a considerable amount of time
and funding. Since affected dogs are often asymptomatic
until a seizure or sudden death occurs, current attempts
in screening for the disease are directed at the healthy
appearing animal. The most sensitive tool has been determined
to be a Holter Monitor examination (24-hour EKG), which
records the dog's electrocardiographic activity over
at least 24 hours. The monitor is strapped to the dog
and electrodes are placed on the chest while the dog
goes about its normal activities. The total number of
beats, including the abnormal PVC's, are recorded. The
electrodes must be correctly placed and the results
must be interpreted by trained personnel. While current
research at Ohio State University by Dr. Kate Meurs,
funded by the American Boxer Charitable Foundation and
the AKC Canine Health Foundation, has suggested certain
thresholds of PVC's or other abnormalities for diagnosis
of the condition, she has also discovered that an individual
dog's numbers may vary from day to day or week to week.
Her ongoing research, and that of others, will hopefully
determine with greater certainty the value of this screening
tool in the future until a definitive genetic test is
available. While it is true that a symptomatic dog usually
has thousands of beats in a 24 hour period and in severe
cases may be diagnosed by simple auscultation of the
heart or by a brief EKG, the Holter monitor is still
probably the best screening tool for early detection,
due to the often intermittant occurrance of the PVCs
in the asymptomatic dog.
Of recent interest to boxer cardiology
researchers is a somewhat similar condition found to
occur in human families, the so-called arrhythmogenic
right ventricular dysplasia (ARVD), in which young and
old persons, previously in good health, experience sudden
death. To our knowledge, attempts to find a precise
DNA marker have not been successful so far, but if this
occurs, it may help veterinary cardiologists find the
canine genetic defect sooner. BCM appears to be unique
to boxers, so far, in the dog world, and is dissimilar
in many respects to cardiomyopathy occurring in other
breeds, such as the Doberman and Great Dane. Continuing
research and follow-up of dogs already under study will
hopefully provide better insight and understanding of
this unique condition in the boxer, as well as more
widespread availability of screening.
Aortic / Subaortic
Valvular Stenosis: AS/SAS
One of the most common heart defects occurring in dogs,
boxers in particular, is aortic or subaortic stenosis.
In most cases the stenosis, or narrowing, is produced
by a fibrous ring of tissue below the aortic valve,
hence the term "subaortic." The disease is
inherited but its mode of transmission is not known
at this time.
Oxygen-rich blood flows from the left
ventricle of the heart, through the aortic valve and
into the aorta, which transports the oxygenated blood
to all organs and tissues in the body except the lungs.
Narrowing of the aortic valve requires the left ventricle
to work harder to pump the necessary amount of blood.
This increased workload can result in hypertrophy (thickening)
of the left heart muscle. Since the blood is being forced
through a smaller-than-normal opening, there is also
increased pressure generated by the pumping action of
the heart. This increase in pressure can cause dilation
(ballooning) of the aorta. Reduced flow can produce
symptoms of fainting (syncope) and even sudden death,
although abnormal heart rhythms (arrhythmias) may also
contribute to these symptoms.
The stenosis creates a change in the flow
of blood through the valve causing turbulence which
results in swishing sound called a heart murmur. Often
the stenosis can be seen on echocardiography. Murmurs
are graded from one to six, but a weak murmur may not
always be detectable, even by a trained cardiologist.
Exercising the dog during the cardiac exam may increase
detection of murmurs in some cases. Not all murmurs
are the result of aortic stenosis/subaortic stenosis,
but may be so-called "innocent," or physiologic
murmurs, particularly when they occur in young animals.
The diagnosis of AS/SAS is best made by
a veterinary cardiologist, or one with equivalent experience
and training. When a murmur is identified and not presumed
to be physiologic, further investigation is warranted.
The least invasive and most available testing consists
of Echo/Doppler.This testing is best performed when
the animal is full grown or at least one year of age,
unless the dog is experiencing symptoms of heart disease,
in which case testing should be pursued promptly.
As in many instances in medicine,
these tests have limitations and are not perfect. False
positive and false negative diagnoses may occur. In
some cases this is simply because the abnormality is
too subtle to be diagnosed with currently available
knowledge and/or technology. Echo-Doppler flow rates
can vary considerably in the same animal depending on
the proficiency of the operator and the amount of stress
to which the animal is subjected. These limitations
may be minimized in part by examiners with advanced
training using the appropriate ultrasound equipment,
techniques, and standards established by the American
College of Veterinary Internal Medicine, Specialty of
Cardiology.
ACEPROMAZINE
There is one drug used in anesthetic protocols that
should not be used on the Boxer. That drug is Acepromazine,
a tranquilizer that is often used as a preanesthetic
agent. In the Boxer, it tends to cause a problem called
first degree heart block, a potentially serious arrhythmia
of the heart. It also causes a profound hypotension
(severe lowering of the blood pressure) in many Boxers
that are given the drug. Recently on the Veterinary
Information Network, a computer network for practicing
veterinarians, an announcement was placed in the cardiology
section entitled "Acepromazine and Boxers".
This described several adverse reactions to the drug
in a very short time span at a Veterinary Teaching Hospital.
All the adverse reactions were in Boxers. The reactions
included collapse, respiratory arrest, and profound
bradycardia (slow heart rate, less than 60 beats per
minute). The announcement suggested that acepromazine
should not be used in dogs of the Boxer breed because
of a breed related sensitivity to the drug.
Further warning from a boxer breeder and
veterinarian
This drug is the most commonly prescribed tranquilizer
in veterinary medicine. It is also used orally and is
prescribed for owners who want to tranquilize their
dogs for air travel. I would strongly recommend that
Boxer owners avoid the use of this drug, especially
when the dog will be unattended and/or unable to receive
emergency medical care if it is needed. Wendy Wallner,
DVM December, 1995
When you first take your boxer to a vet
(or to a new vet), for any kind of treatment have them
write in red on the outside of the patient record "NO
ACE". Be firm! If they refuse to do this then I
would immediately remove my dog and find another vet.
Don't be fooled by an uninformed
vet...this is a matter of LIFE AND DEATH! |