Dogs and cats can have heart failure due to progressive changes within the heart associated with the heart muscles or heart valves. This initial symptoms may include coughing, exercise intolerance, increased breathing rate and a heart murmur may be heard when the vet listens to your pet’s heart with a stethoscope.
Heart failure can be staged according to the severity of the signs and therapy can be selected from the options reviewed below based on the patient’s stage. Stage is determine via physical examination, symptoms, x-rays and ultrasound.
Clinical stages of Heart Failure
STAGE I > The patient has heart disease but there are no clinical signs of any kind.
STAGE II > The patient has heart disease and clinical signs of heart failure occur with exercise but not at rest.
STAGE III > Heart disease is producing clinical signs of failure with day to day activity.
STAGE IV > Severe signs of failure are present even at rest.
Patients in Stage IV require emergency care. However patients with Stage III and below can be managed on oral medications usually as outpatients. Not every patient will respond to therapy and it may take weeks to achieve the desired balance.
In most heart failure scenarios, the heart is unable to handle the blood volume with which it is presented. Fluid backs up and leaks out, creating either fluid in the lung (pulmonary edema) or fluid buildup in the belly. The more sodium the pet ingests, the higher the blood volume.
Studies have indicated a diet of moderate-sodium levels is ideal for a cardiac patient. These are commercially available or can be home-cooked.
Omega 3 Fatty Acids
Supplementation with omega 3 fatty acids is currently being researched as a possible treatment for the drastic weight loss (cardiac cachexia) that occurs with some cases of heart failure. If a pet enjoys these fishy flavored supplements, this may be a particularly helpful way to encourage appetite.
People often ask how much restriction in exercise they should impose. Your pet should guide you on how much exercise they require. Generally a gentle walk is adequate. Avoid exercise that leads to excessive panting or weakness.
Diuretics help draw the fluid caused by heart congestion out of the body cavities. Whilst the drug is extremely effective in these cases, overuse can damage the kidneys so a careful juggle of dosing is required. Frusemide is usually the first-choice diuretic in cardiac patients and is often used in combination with other cardiac medications. Spironolactone is another diuretic commonly used especially in patients who do not respond adequately to furosemide alone.
When an animal is placed on diuretics, the vet will likely monitor blood kidney parameters and reduce the dose to as low as possible to avoid the above mentioned kidney side effects. This drug will also cause your pet to drink a lot more and urinate more often.
This drug blocks the Angiotensin cascade from occurring which means we get less sodium retention and keep blood vessels open. This helps effectively pump blood through the vessels around the heart and around the body taking some of the pressure off the heart.
However ACE inhibitors also reduce blood flow through the kidney, drop blood pressure and cause potassium retention so like diuretics we must use these with caution and monitor kidney parameters closely.
Pimobendan works by helping the heart pump more efficiently and strongly. It also dilates blood vessels both going to and from the heart thus giving the “extra” blood a place to go so as not to overload the heart. This drug has been recently proven to significantly slow progression of heart disease even before it is symptomatic so we will commonly start patients on this drug first followed later by the addition of other drugs such as ACE inhibitors or diuretics as listed above.
A patient’s breathing or respiration rate is an excellent indicator of how they are coping with their heart disease. Your vet will likely ask you to monitor your pet’s respiration rate at home. This is best done over 1 minute whilst they are at complete rest (e.g. sleeping). A rate of great than 30 breaths per minute indicates they are struggling and a vet check is warranted particularly if this is repeatable over a few days. Rates over 50 breaths per minute are very abnormal and should be addressed urgently.
Your vet will likely recommend they see your pet every 3-6 months to assess how their heart is going. This will involve a physical exam and careful auscultation of their chest as well as a discussion of how their breathing is at home and whether they are coping with exercise. Your vet may also run blood panels to monitor their electrolyte and kidney function and ultrasounds or x-rays might be needed to determine the progression of their heart disease.