Mitral Valve Dysplasia in Cats

Mitral valve dysplasia is a hereditary birth defect that prevents the heart from developing properly. Specifically, it affects the heart valve responsible for regulating the flow of deoxygenated blood into the heart by making it too weak to adequately contain the fluid pressure that builds up during contraction of the heart muscle. This means that not only is the strength of circulation dramatically decreased, but blood will pool in the tissues surrounding the heart (namely the lungs). Although serious, the condition is manageable by administering the relevant drugs, which can go a long way to improving a cat's quality of life. 

As with many internal congenital problems, it can be difficult to notice if your cat is suffering from mitral valve dysplasia. There are, however, some tell-tale signs that will often aid in diagnosis.

Breathing Problems

One of the immediate effects of mitral valve dysplasia is a marked increase of fluid in the lungs. This is caused by the pressure that the 'backlog' of blood waiting to enter the heart can put on the surrounding tissues. It is common for cats suffering from the condition to exhibit shortness of breath and wheezing from an early age. A habitual cough may also develop, as the animal will be frequently experiencing discomfort from excess fluid in the airway.

Unwillingness to Exercise

Although all cats are often characterized as lazy, one of the tell-tale symptoms of heart problems is a flat-out refusal of your pet to engage in normal levels of movement and activity. This is due to the difficulties they may be having in breathing during cardiovascular exercise paired with the uncomfortable strain that it places on their malformed heart tissues.

Fainting

Just as humans suffering from serious heart problems can be prone to blackouts, so can our pets. This is caused by the inability of the cat's heart to circulate enough oxygenated blood around the body as it is needed.

The main cause of mitral valve dysplasia is genetic. Due to a lack of external pressures on the modern feline population, such serious birth defects are no longer the death sentence that they were in the wild, meaning that animals with such conditions are able to live to an age when they are capable of passing on their genes. Unfortunately, there are very few practical ways to screen for such defects, meaning that there is no way to know for sure until the cat starts to exhibit outward symptoms.

The condition can also be caused by tumors of the thyroid gland (which is responsible for many regulatory processes in the developing body). This can, in turn, cause the heart muscles to excessively thicken, contorting the mitral valve in the process.

Upon presenting your cat to a vet, they will often perform a full blood panel in order to determine if there are any other defects present that could help them isolate the exact nature of the problem. They will also perform scans of the chest cavity and heart using x-rays and echocardiography devices, as well as possibly using an electrocardiogram monitor to eliminate the possibility of the symptoms being caused by a case of arrhythmia instead. These tests will also help rule out a problem with any of the other heart valves, as deformation of these can cause similar symptoms to occur. The vet may also have questions for you regarding your pet's behavior and any problems the cat has had so far (so it is best to have their medical history readily accessible).

It is quite likely that the vet will either diagnose your cat with mitral valve dysplasia or go beyond that and diagnose congestive heart failure. Although congestive heart failure is very serious, it is most often treated with the same methods used to combat valve dysplasia in any case.

Depending on diagnosis, the vet will most likely recommend fighting the condition with a combination of the following methods:

Vasodilator Drugs 

Vasodilators will maintain the dilation of blood vessels. This will decrease the cat's blood pressure (making exercise easier) and stop it from developing circulation problems to its extremities.

Antiarrhythmic Drugs 

An antiarrhythmic will keep all the chambers and valves of the heart contracting and expanding in the correct order. This will go a long way towards preventing the faulty valve from allowing blood to be pushed backward into the adjoining veins. 

Diuretics 

Diuretic drugs are key to preventing fluids from building up and impacting your pet's quality of life. This is done by promoting increased urine production, meaning that excess liquid that would once have pooled in the lungs will now be expelled from the body. This increased loss of water can also result in radical weight loss, so be sure to keep track of your cat's health before follow-up visits to the vet.

Note that these drugs are almost always delivered in pill form, and commonly are crushed into food to aid delivery.

In the event of a thyroid tumor, surgical intervention may be necessary to prevent it from spreading throughout the body.

As mitral valve dysplasia in cats is a congenital condition, there is little that can be done to 'cure' it. However, the treatment options outlined above will drastically improve your cat's quality of life.

In addition to the prescribed drugs, your vet will most likely want to schedule periodic follow-up appointments, when tests similar to those used to perform the initial diagnosis will be used to track how far the condition has abated. These follow-up appointments are also an ideal time to discuss alternative drugs if you feel that one of the ones prescribed is having undesirable side effects.

After treatment has begun, you may notice a sudden change in your cat's behavior, with them becoming more willing to exercise, explore and roam. Because of this, your vet may advise you to get the cat sterilized (if it is not already) to prevent them from mating and spreading the condition via their offspring.