By far the most common lung disease that we see in cats is asthma. Officially known as Feline Asthma Bronchitis Complex, or FABC, there are a variety of causes for asthma in cats. Less common lung diseases include bacterial pneumonia, fungal pneumonia, tracheitis, and cancer metastasis. Not technically a lung disease, but affecting the lungs, is pleural effusion, which consists of fluid building up outside of the lungs. This can include congestive heart failure, chylothorax, pyothorax, FIP, infectious feline leukemia, and of course, cancer.
Asthma is unfortunately fairly common in cats. If your cat is coughing more than once or twice a month, then there is a reasonable chance that they have asthma. If you are not sure what a coughing cat sounds like, it is kind of like trying to hack up a hairball, but nothing comes up, and it can seem to last longer than just hacking up a hairball. Rather than rewrite a description of feline asthma, there is an excellent website that goes through the pathogenesis of asthma and the treatment options involved. The website is at www.fritzthebrave.com. Even though this website was written by a non-veterinarian, it has been reviewed by multiple veterinarians and is an excellent resource for feline asthma information. If you think your cat might have asthma, the first thing we would do would be to do an x-ray to look for signs of chronic lung congestion. If we feel that your cat likely has asthma, we will probably start your cat on a combination of steroids and bronchodilators. These can be given in a variety of ways, from pills to liquid, and injections to inhalers. Yes, you can give your cat an inhaler. See the website listed above for more information. If treated correctly, asthma does not necessarily mean your cat's life span will be shortened.
Bacterial pneumonia. If your cat was sick with an upper respiratory infection recently, and we hear lovely crackles in their lungs when we listen to them, or they are suddenly coughing or open-mouth breathing, there is a good chance that your cat developed bacterial pneumonia. This is very treatable, but depending on just how sick your cat is, they may need to spend a little time at the clinic in an oxygen cage while we treat with multiple antibiotics.
Fungal pneumonia. Rare, but we do see it. This can take years to come on to the point where we see clinical signs, and by the time we see clinical signs, you have a very sick cat. The most common fungus implicated in fungal pneumonia is histoplasmosis, but other fungal organisms can cause it as well. We may want to do several tests, including a blood test and a fine needle aspirate of the lungs to diagnose the fungal pneumonia, but once we diagnose it, we will put your cat on an antifungal medication for several months. Because antifungal medications can have some fairly serious side effects on bone marrow and the liver, we will want to do pretty regular blood tests on your cat while they are on treatment to make sure that they are tolerating the medication okay. Don't ask what happens if they can't tolerate the medication. We cross that bridge when we come to it.
Tracheitis. This is rare in cats, but can be fatal if not treated. This involves inflammation in the trachea that results in a thick coating of mucus building up in the trachea. The most common organism to blame is bordetella (aka kennel cough), but it is not the only one. We may culture the mucus in the trachea to determine the bacterial cause and what antibiotics will work most effectively.
Cancer metastasis. Back to that nasty little bug. A lot of malignant cancers will metastasize, which means spread to other organs, and the lungs are a favorite place for cancers to metastasize too. Once cancer has spread to the lungs, chemotherapy is unlikely to have the desired effect. That doesn't mean it isn't worth trying, but sometimes we just want to get the best quality of life for our cat, even if it means a shorter life.
Congestive heart failure. This can affect both the inside of the lungs and the outside of the lungs. When the heart is failing and cannot adequately pump all of the blood, the blood starts to back up to the least area of resistance. With left-sided heart failure, that is the lungs. A lot of biochemical and biophysical factors decide whether the fluid goes into the lungs or in the chest cavity outside of the lungs. Either way, your cat suddenly has a hard time breathing, then maybe a few hours before they were fine. If the fluid is inside of the lungs, that can be treated with high doses of diuretics.
If the fluid is outside of the lungs, also known as pleural effusion, then we can perform what is called a thoracocentesis where we will stick a needle directly into your cat's chest cavity, and using a large syringe, draw out as much fluid as we can. This procedure is not without risks. The less fluid left in the chest, the closer the moving lungs can get to that needle sticking in there. While we take precautions to minimize how much the needle sticks in, it can still happen that the needle will lacerate the lungs resulting in hemorrhage that may or may not stop. However, this is the best way to get the fluid out of your cat's chest in a fast manner so they can breathe again before they go into respiratory arrest, which is not good and can be followed by cardiac arrest.
Chylothorax is an uncommon disorder where lymphatic fluid will build up in the chest cavity. Sometimes this is because a lymphatic duct ruptured, sometimes this is a result of lymphoma, and sometimes we just have no idea what caused it. The only immediate treatment for this is thoracocentesis, but there is always a chance that it will come back. There is an herb called rutin that has been shown to minimize the reoccurrence of chylothorax, but it is not a complete preventative. Some cats will develop chylothorax once, and never again. Other cats will keep filling up with in their chest until either their owner says enough, or until they develop so much scar tissue in their chest that there is nothing more that we can do. Surgery can be performed to try and find and fix the ruptured duct, but since we don't always know if that is the cause, it may not be successful, and since in involves thoracic surgery, you are looking at a high cost and probably traveling to find a board certified surgeon who can perform it.
Pyothorax is very rare, which is good, because we have a hard time treating it at an average veterinary clinic. Pyothorax is an accumulation of pus from infection in the chest cavity. Antibiotics have a hard time penetrating into this large volume of infection. It needs to be repeatedly drained, but it is so thick that it will not generally go through a needle, and so a chest tube needs to be placed, which tends to require 24 hour care, such as in an ICU. If we think your cat may have pyothorax, we will recommend that you go to a 24 hour facility, such as Kansas State University Veterinary Medical Teaching Hospital for treatment. If that is out of your price range, we will throw all kind of antibiotics at it, but it is a crapshoot as to whether or not we can get the infection under control in time.
FIP. This disease just plain sucks. It tends to hit the very young and the very old, and no one yet can predict what causes it in some cats, and not in others. While most commonly it affects the abdominal cavity, hence the "Feline Infectious Peritonitis", peritonitis meaning inflammation of the abdominal cavity, it can also affect the chest cavity. While dry FIP has a fighting chance of a slim percent of survival if we can find it early enough, wet FIP, which is what would cause fluid accumulation in the chest cavity has a 99.99% fatality rate. If we diagnose your cat or kitten with wet FIP in the chest, we will probably recommend euthanasia, rather than letting your cat continue to suffer with no real hope of getting better.
Feline leukemia. We don't see this result in fluid build up in the chest cavity very often, but if you have a young cat or kitten that suddenly can't breathe, and we do a leukemia test and it is positive, we will also recommend euthanasia. Cats don't survive this when it gets to the point of fluid in the chest cavity.
Cancer. And then, of course, there is our old enemy cancer. Wow, these last few are pretty depressing. The most common type of cancer that will cause fluid build-up in the chest cavity is lymphoma. This can hit at any age, from 1 to 25. Again, not a whole lot we can do. We can also see primary lung cancers such as large cell carcinoma. These can progress fairly slowly in cats, but by the time we start to see coughing, it is pretty much everywhere. If we can determine the type of cancer and the source, chemotherapy may have some benefits and buy your cat a few more years of quality life. If chemo is not something you are interested in pursuing, then if pleural effusion is present we can drain the chest and put your cat on very high dose steroids, but that is only to buy you a few weeks or months. It will most likely come back. Okay onto the next page and things that are more fixable.