Heart Disease – Common Symptoms and their Mechanisms

Author: Katt

Cough

Cough is a common symptom of heart disease and heart failure in ferrets (and humans). A cough can be due to a variety of non heart-related problems and should always be evaluated thoroughly by your vet. In some ferrets, heart enlargement may result in pressure on the trachea leading to a chronic cough. The more common and classic cause of cough in a ferret with heart disease however, is fluid accumulation in the lungs due to a back-up of pressure in the circulatory system called venous congestion.

In Heart Failure the heart is not able to pump blood effectively; meanwhile, blood from the circulatory system is still trying to enter the heart. The best analogy for this is a hose with tiny holes in it. When the water pressure is low or normal, the holes might drip a little but the majority of the water flows out of the hose nozzle. However, if you turn the water up to high pressure, and squeeze the end of the hose so only a little water can exit the nozzle, the water has nowhere else to go and will spray through the holes at a much higher volume. The same thing happens in the blood vessels. The increased pressure causes fluid from the circulatory system to leak out of the vessels and into the body or lungs – called fluid extraversion. When the fluid leaks into the lungs, Pulmonary Edema develops. When fluid accumulates around the lungs, it is called Pleural Effusion.

Pulmonary Edema can be seen as fluid in the lungs on X-Ray, where the lungs will typically appear more hazy and white than normal lungs. This fluid causes a chronic cough, as well as difficulty breathing. In ferrets this can manifest as symptoms such as:

• rapid, shallow breathing
• reduced energy and loss of interest in play
• reduced stamina
• flat ferreting
• raspy, squeaky, or gurgly breathing sounds

Here is a video showing Koda demonstrating raspy breathing (beginning of video – turn up volume) and a characteristic but severe cough due to heart failure:

Edema (“Pear-Shaped” abdomen, bloat)

In the same way that fluid can back-up into the lungs, fluid can also back up into the body causing swelling. In humans this often appears as swelling in the legs, in ferrets this appears more in the hips and abdomen, causing the characteristic pear-shaped abdomen.

Another form of fluid buildup, called ascites, can also occur when heart failure becomes so severe that the blood flow in the liver becomes congested, leading to liver failure (see hepatosplenomegaly below) and further fluid accumulation in the abdomen.

 

 

 

 

 

 

 

 

 

 

 

 

 

Fatigue and Weakness

In Heart Failure, the heart is not able to pump enough blood to deliver enough oxygen and nutrients to meet the needs of the rest of the body. Fatigue may occur both due to difficulty breathing from pulmonary edema (fluid in the lungs), as well as due to insufficient oxygen delivery to the body and lungs. Additionally, the lack of oxygen and nutrient supply to the muscles and other tissues can result in weakness. As the ferret becomes fatigued more and more easily, they spend less and less time being active; as a result they lose more of their muscle mass. This creates a cycle of progressive fatigue and weakness.

Light-Headed or Reduced Alertness

The brain, like other tissues in the body, requires oxygen from the bloodstream in order to function properly. In early heart disease or failure the body is able to compensate, and maintain adequate flow to the brain. As Heart Failure progresses however, it may reach a point beyond which the body can compensate, and the brain begins to be deprived of oxygen and nutrients. Several of the medications for heart disease and heart failure work by reducing blood pressure. If blood pressure drops too low, the brain will also be deprived. This can cause a ferret to feel light-headed and if severe enough, they may even pass out. If this happens you need to get to an emergency vet ASAP. Light-headedness is difficult to assess in ferrets, who cannot tell you what they are feeling. Watch for signs such as:

• weakness
• worsening fatigue and flat-ferreting
• tooth grinding (may be a sign of nausea or pain)
• decreased alertness

If these symptoms occur, you need to seek veterinary care immediately.

Hepatosplenomegaly (Enlarged Liver and Spleen)

Venous congestion (backed-up pressure in the vessels due to the heart’s failure to pump blood effectively) can have significant effects on the liver and spleen. Using the clogged hose analogy again (see Cough above), imagine a hose in which you clamp off the end and turn the water up to full pressure – the hose will eventually give and start to expand. This occurs in the blood vessels also, causing dilated veins in addition to the fluid leakage (extraversion), which can then cause the liver and spleen to become engorged (aka enlarged). Eventually, liver failure will develop as a result.

Blood Clots – Stroke, Saddle Thrombus

Another potential result of heart disease is the formation blood clots. In a ferret, this is usually catastrophic. Blood clots may occur in early heart disease, often before a diagnosis has been made, as well as in advanced heart disease and heart failure. When the heart is not pumping effectively, blood does not flow well and some amount of blood may pool in the heart or in other parts of the body. The pooled blood begins to coagulate, and a clot is formed. Pieces of a clot formed in the heart or a larger vessel may then break off and travel to narrower vessels where they get stuck and block off blood flow to the surrounding tissues – this is called a thromboembolus or embolus. Alternatively, a clot may form in a vessel and block flow where it sits, without pieces breaking off – this is called a thrombus. Blood clots can form in many places of the body, but two of the most common clots are a stroke and a pelvic saddle thrombus, described below.

Stroke: a blood clot that blocks flow to the brain causes a stroke. A few common symptoms of stroke in a ferret include staggering, walking in circles, falling to one side, weakness of one limb, or weakness both legs on one side of the body.

Saddle Thrombus: a blood clot that blocks flow at a major branch point of large vessels is called a saddle thrombus. This happens most often in the legs or lungs. In the legs, sometimes called a pelvic saddle thrombus, a clot from the heart travels down the aorta and gets lodged at the division to the iliac arteries. This blocks flow to the entire hind-end including the hips, both hind legs, and tail. Symptoms include paralysis of the hind legs, and severe pain. Most often, the animal must be euthanized. However, there are a few rare cases in which immediate intervention with anticoagulant medications has been successful. Dr. Holly Carter at Evergreen Avian and Exotic Animal Hospital in Kirkland, WA successfully treated one of HFF Moderator’s ferrets Mickey. Read Mickey’s Story Here.

In the lungs, the clot blocks off the pulmonary arteries, stopping blood flow to the lungs. This typically results in death.

Below is a link to a video of one of HFF Admin’s ferrets, Captain Jack, after recovering from a Pelvic Saddle Thrombus. He has recovered significantly in this video, but you can still see his residual hind-limb weakness. Note also the large abdomen due to his underlying heart disease.

Click for Video

Please Note that we do NOT promote the use of rubber toys in ferrets due to the high risk of Blockages – Captain Jack was ONLY permitted to play with this toy while being snuggled (with constant hands and eyes on supervision).

 

 

 

 

 

 

References:

1. Johnson-Delaney, C. (2017). Ferret Medicine and Surgery. Boca Raton, Fl: Taylor & Francis Group, LLC.
2. Lewington, J. (2007). Ferret Husbandry, Medicine, and Surgery, 2e. Philadelphia, PA: Elsevier.
3. Quesenberry, K., Carpenter, J. (2012). Ferrets, Rabbits and Rodents Clinical Medicine and Surgery, 3e. St. Louis, MO: Elsevier.