There are several diseases that are related to Feline Asthma. Lungworms, heartworms, upper & lower respiratory infections, lung cancer, cardiomyopathy and lymphocytic plasmacytic stomatitis can all mimic asthma symptoms and therefore should be ruled out. Please note that these diseases, particularly heartworm, react favorably to steroid treatment, so you cannot assume that it is in fact asthma simply from a favorable reaction to treatment. Diabetes and kidney disease can result from feline asthma treatment.

Lungworms
Lungworms are parasitic nematodes that require an intermediate host for infection to cats. The route of infection for lungworms is oral. Lungworms can be ruled out by a fecal test.

Heartworms
How Come All of a Sudden You are Telling Us Cats Can Get Heartworm?

Veterinarians have been missing the diagnosis of heartworm disease in cats for years. We long believed that the cat disease was rare, and if seen would look like the dog disease, i.e. progressive cough leading to heart disease, wasting away, followed by death from heart failure. Recently we've learned that only the very rare case of cat heartworm disease looks like this. Because of new testing procedures we have found that feline heartworm disease is much more common than we ever thought. The majority of cases were diagnosed as chronic bronchitis or asthma. In fact if you have a cat who was diagnosed with asthma or chronic bronchitis in the past and was well controlled with cortisone, he may have had heartworm disease. Asthma, chronic bronchitis and heartworm infection cause inflammation of the lungs and all are treated with cortisone. Therefore even if your heartworm infected cat was misdiagnosed as having asthma, he was treated with the appropriate drug for heartworm disease and probably recovered.

Heartworms are parasitic nematodes that require an intermediate host for infection to catsThe route of infection for heartworms is through the skin; they are transmitted to cats by mosquitoes that carry the larvae. Heartworm does cause coughing in some cats. Heartworms are difficult to diagnose. There are two kinds of tests for feline heartworms: antigen and antibody. The antibody test only indicates exposure not infection with worms, which can lead to false positives. The antigen test looks for a specific hormone that the worms release and so it is evidence of a current infection. However, because most cats have a very low worm load, and presumably low circulating antigen levels, the odds of a false negative are good. Cardiac ultrasound is additional diagnostic tool that can also assess the current health of the heart as well as provide an idea about worm load.

Because of a lack of substantial symptoms associated with heartworm disease in cats and the high risk involved in treatment, most often it is recommended that the cat begin heartworm prevention (Heartgard/ivermectin) to prevent the current worms from reproducing while waiting for them to complete their lifespan which is about two years. The death of the worms may be uneventful so that the body absorbs their remains or may cause a cardiovascular obstruction that could be fatal.

Heartgard (active ingredient ivermectin) works to kill the larvae that circulate in the blood vessels before developing into the adult heartworm. Ivermectin has no effect on adult heartworms. Ivermectin toxicity in cats is only a concern at much higher doses than Heartgard provides, is more common when it is injected subcutaneously, and such toxicity is unrelated to current infection with heartworms.

Feline Heartworm information from the American Heartworm Society

Ray Dillon, DVM, MS - Heartworm information

Upper Respiratory Infection
A detailed report on upper respiratory infection.

Lower Respiratory Infection
A detailed report on lower respiratory infection.

Lung Cancer - From PetProspects
Unlike humans, felines usually do not have tumors that originate within the lungs. In cats, the tumors are found elsewhere in the patient's body and they have merely spread (metastasized) to the lungs. As tumors grow, cancer cells tend to break away and float through the bloodstream. These cancer cells frequently lodge in the small vessels (capillaries) of the lungs and grow to form tumors. Eighty percent of all lung tumors of cats are termed adenocarcinomas. These are malignant (life threatening) cancer growths that grow from abnormal glandular tissues in the intestines, uterus or mammary glands. Skin and bone cancer may also spread to the lungs.

The symptoms of lung cancer depend on the number and size of the tumors. The one universal symptom is difficult breathing. As the normal lung tissue is destroyed by the growing tumors, the patient tends to exhibit labored breathing that is rapid and shallow. Patients with lung cancer may also experience coughing, occasionally bringing up bloody mucous. In advanced cases, the patient will lose weight and eventually die. As mentioned earlier, other tissues in the cat are usually involved. Other symptoms depend on which other organs or areas of the body are also affected.

Cardiomyopathy
Prolonged coughing can sometimes lead to heart trouble by enlarging and thickening the heart. This is not true cardiomyopathy but may show as slightly enlarged heart on ultrasound.

True cardiomyopathy will present with the heart as an abnormal shape and fluid may be detected in or around the lungs. If a large amount of fluid is present around the lungs, it may be necessary to remove it and take more radiographs because the presence of this fluid interferes with evaluation of the heart. Ultrasound and electrocardiogram (EKG) are common tests for cardiomypopathy.

Lymphocytic Plasmacytic Stomatitis
An auto immune condition, which generally affects the gums and Mouth and is caused by an overactive immune system. It is linked to viral infections such as Calici and Herpes, but there also appears to be a genetic component as well. The precise cause of the condition is unknown. Severe cases can affect nose and sinuses as well, causing wheezing and laboured breathing due to inflamation in the nose and throat. This condition is typically treated with oral steroids.

Diabetes
Long term use of oral steroids can in some cases lead to steroid induced diabetes. Fortunately, it is not that common ho wever, senior cats, long term steroid users and particularly long acting steroid shot (Depo) users
are more at risk.

The warning signs to look out for are excessive drinking and urinating, extreme hunger and weight gain or inappetance and weight loss. The animal generally becomes lethargic, as the blood glucose is not converted into energy.

Diabetes is easily diagnosed with a blood test which will show an elevated blood glucose however, if in the early stages, this can sometimes we written off as stress, because stress also has the affect of increasing blood glucose. For this reason, always have regular blood work done, particularly for senior cats.

Diabetes is a very serious disease and left untreated, causes damage to the heart, kidneys, circulation and causes muscle wasting, and can lead to a premature death. It also leaves the body ripe for opportunist infection, particularly oral and urinary.

The Original Internet Guide to Feline Diabetes

Harry's Blood Glucose Testing in Diabetic Pets.

Kidney Disease/Chronic Renal Failure
Long term steroid use can play a part in the early onset of kidney failure. Symptoms to watch out for are excessive drinking and urinating, nausea and vomiting. Obviously, if your pet does display any of these symptoms, he/she should be taken to a vet ASAP where the kidney function can easily be assessed with a simple blood test, which will show elevated BUN and Creatinine if there is a degree of renal insufficiency. Other blood values may also be out of whack, depending on the stage the disease has reached. There can be other reasons for elevated blood renal values, such as intestinal blockage however, your vet will be able to assess this.

Feline CRF Support Forum

Caring for CRF Felines Yahoo Group

Feline CRF Information Centre

Allergies and Asthma
Double trouble: The link between allergies and asthma