Heart Conditions: Grave and Chronic

It seems an ironic shame that a breed capable of such love and devotion can suffer from diseases of its generous heart. Heart disease is not rare among Chihuahuas. Moreover, several forms of heart disease are found to occur three to six times more frequently in Chihuahuas than in most other breeds. Since bad luck appears to come in threes, perhaps it's not so coincidental that the Chi suffers from three heart diseases: patent ductus arteriosus (PDA), pulmonic stenosis, and chronic valvular disease, or endocardiosis.


This disease occurs when blood is abnormally moved through a shunt from the left to the right side of the Chi's heart, causing increased blood to flow to the lungs. This in turn causes a buildup in fluid and a strain on the left side of the heart. Symptoms that a Chihuahua is suffering from a serious case of PDA include coughing, weight loss, exercise intolerance, and (eventually) congestive heart failure.

If a Chihuahua is diagnosed with a more serious form of PDA, and the disease is caught within the first two years of the puppy's life, surgery can resolve the shunting of blood from one side of the heart to the other. If PDA is not discovered until later in life, surgery is not as successful at this time.

Is it possible to have PDA and not be seriously ill?

Yes. Some Chihuahuas have an incomplete shunt or one that allows only a trickle of blood through from left to right. In these cases, a Chi may live without symptoms or any significant health repercussions.

Pulmonic Stenosis

This heart disease is caused by a malformation that creates an obstruction in the right side of the heart that prevents full flow of blood from the heart into the lungs. The extent of this obstruction dictates how seriously ill your Chihuahua could become. If the blood flow is restricted to the point that the heart must work very hard to function, this work overload will result in congestive heart failure. On the other hand, a slight obstruction may go completely undetected. In severe cases, surgery is often recommended to remedy the situation.


Chronic mitral valvular disease (CMVD), also known as endocardiosis, is an acquired heart disease that results from the degeneration or loss of elasticity of the heart's valves. Male Chis tend to be affected more often than females and older Chis more often than young adults. When the edges of the heart valves degenerate, they lose their perfect seal and allow the backflow of blood into the heart, which can be heard as a murmur. Whenever there are leaks, the dog's circulation is compromised, and eventually the Chi will begin to show signs of heart failure. Symptoms include the following:

  • Lethargy

  • Loss of appetite

  • Depression

  • Coughing, difficulty breathing

  • Weakness

  • Dizziness, disorientation, fainting

  • Distended abdomen

  • At the current time, there is no cure for heart valve complications; however, there are many drugs available to help ease the Chihuahua's discomfort and help extend the length and quality of life, in some cases substantially.

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