One of the most common heart defects occurring in dogs, boxers in particular, is aortic or subaortic stenosis. In most cases the (stenosis) 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 currently known. 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 and techniques.

 

This is one of the true emergencies in veterinary medicine

 

 

 

Gastric Dilation (bloat) with Volvulus (torsion), or GDV.
 
Simply put, bloat describes a stomach which has become abnormally enlarged or distended. The stomach is filled with gas, food, liquid, or a combination of both. Torsion is the abnormal positioning of the stomach which is caused by the stomach's rotation about its axis, i.e. twisting of the stomach. Bloat usually leads to torsion, although torsion can occur without bloat.  Depending on how quickly the problem is dealt with, GDV may result in a stomach that is rotated by anywhere from 90° to 360°. Severe torsion usually means the displacement of both the stomach and the spleen (they exchange positions). The speed at which the stomach empties itself, as well as the stomach's digestive contraction pace, are thought to play a role in the development of GDV.
GDV most commonly occurs in large, deep-chested breeds, but has also been reported in Bassets, Dachshunds and cats. 

It is of major importance that you make sure that your veterinarian is familiarized with the proper procedures before his/her skills are needed, never be shy to enquire. If your veterinarian is not receptive to or is offended by your queries, then it may perhaps be time for you to find a more responsive veterinarian. 

Early signs of bloat may include

restlessness
excessive drooling
pain in the abdomen
retching
and/or non-productive attempts to vomit.
The dog may vomit foamy mucous, or a mucousy foam may be evident around the lips.

A more advanced sign of bloat is characterized by

enlarged abdomen Some people have reported early detection by observing abnormal behavior, such as not wanting to move around; or laying down in a curled up position, etc. when the dog would normally run around and play. During this early phase, stomach enlargement may not be visually evident yet. Bloat can usually be detected when you make the dog stand up and gently feel his/her abdomen. The abdomen should feel soft and tapered inward when the dog is relaxed. If the abdomen feels hard, or sounds hollow (like a drum) when you tap it gently with your hand, then your dog is probably bloating or even torsioning.
pale gum colour

If you're not sure, get the dog in to the veterinarian (or at least call) right away just in case--it's better to be safe than sorry.

Prevention

There are no sure-fire ways to prevent or predict GDV. Below is a list of suggestions :
Feed 2 or 3 smaller meals daily (as opposed to 1 large meal) ensuring the food/water bowls are raised to minimise the intake of air when eating/drinking.
Any changes in the diet should be made gradually, over a period of a week.
Vigorous exercise, excitement and stress should be avoided from 1 hour before to 2 hours after meals.
Excessive drinking should also be avoided.
Avoid feeding food that are known to cause flatulence (gas), e.g. soy, beans, peas, onions, etc.
Some veterinarians advocate the feeding of large pieces of fresh/raw fruits and vegetables (e.g. apples, oranges, carrots) 3 to 4 times a week. The reason is that commercial dog food lacks the appropriate amount of roughage that a dog needs in order for the stomach to function properly.
Some people give their dogs over-the-counter anti-flatulent just before or after they put their dogs through stressful situations. 
On dogs known to be highly susceptible to GDV (e.g. ones that have already bloated before) discuss the use of medicinal prevention with your 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.

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 date, attempts to find a precise DNA marker have not been successful, 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.

Degenerative Myelopathy (DM)

Degenerative myelopathy (DM), a potentially debilitating neurological condition that can eventually paralyze its victims, can occur with relative frequency in Boxers. Unfortunately, the cause of DM remains unknown, although researchers are working to find answers.

What is particularly frustrating is that signs of the condition - progressive spinal weakness and paralysis - do not usually appear until later in life, after a dog has been used in a breeding program.

Understanding DM

Signs usually appear when a dog is between 5 and 9 years old. It begins with a loss of coordination in the hind legs. The dog may wobble or drag its feet. The condition generally results in rear leg paralysis in approximately three to six months, foreleg paralysis in about another three to six months, and respiratory failure approximately three to six months later.

No pain appears to be associated with the paralysis, other than the dog wanting to continue life as before but being unable to. Both sexes appear to be equally affected.

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 looseness is associated with the tissues which surround and hold the joint in place; tendons, ligaments, connective tissue, and muscle, and this laxity leads to bony abnormalities of the ball and socket. While the looseness of the joint is not believed 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.  

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.

 

 

 

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.

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 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.

 

 

 

 

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