If you notice any symptoms that could be asthma, take them to the veterinarian for a complete diagnosis. Below are some of the tests you can expect your pet to receive.
The first step your vet will take will likely be a chest x-ray. The veterinarian looks for such irregularities as: Inflammation around the airways in the lungs (doughnuts), A flat-looking diaphragm (a healthy diaphragm should be round), and a partial collapse of the lung. Additionally, apart from the characteristic donut shapes you see, chronic inflammation and/or infection will appear as white fluffy clouds on the plate. Infection generally leads to an abundance of fluid and fluid tends to pool in the affected area. Your vet should be sure to differentiate between fluid associated with infection or a cardiac problem, because heart problems may not be visible on x-ray. However, some cats suffer both cardiac and respiratory disease combined so if in doubt, your vet should send the x-rays to a vet qualified to interprete them. Cardiac problems can be further confirmed with EKG and/or cardiac ultrasound, which sometimes show enlargement or valve abnormalities. .Not all asthmatic cats lungs appear abnormal in an x-ray, however, particularly if your cat is in the early stages of asthma.
Your veterinarian will also likely take blood work. Blood work can be useful in determining infection, because you will generally see an elevated white blood cell count during an acute infection however, if there has been a low grade undiagnosed infection present for some time, the white cell count may not be elevated at all. It can also be used to assess raised levels of esoinopils, mast ceels, neutrophils and macrophages all of which can be associated with respiratory disease. Blood tests can also check the major organ functions (liver, kidney, heart) and help rule out other disease causes such as diabetes.
Bronchoalveolar Lavage (BAL)
The most definitive test available is the Bronchoalveolar Lavage (BAL), which involves taking a mucus sample from the bronchioles and studying it under a microscope to determine whether there is an increased number of eosinophils (a type of white blood cell). This test is also useful for ruling out lung cancer.
There is some debate about relying on the Bronchoalveolar Lavage (BAL) when infection is suspected. First off, if an animals lungs are in a serious state, the anaesthetic risk needs to be very seriously weighed.
High quality culture sampling by Specialist labs are crucial. Mycoplasma infection is a common infection and Tetracycline antibiotics (Doxyseptin) must be employed here. They cannot be combined with any other antibiotics and you must ensure that the pill is swallowed because in cases where the drug has lodged in the trachea, it causes very painful ulcers. Bordella infection must also be ruled out, commonly known as kennel cough. These two infections cause bronchial disease in cats and are commonly missed by the standard lab cultures.
Infection can exist deep in the lung and when this occurs, it can be impossible to ever get a good sample. If there is no obvious infection present in the mucus sample obtained, infection may be wrongly ruled out so your vet should consider giving a short course of antibiotics to see if an improvement is noted before proceeding to standard asthma drugs, including steroids. Vets tend to avoid combining initial antibiotic therapy with steroids, because steroids suppress the immune system and can therefore interfere with the body's ability to fight infection. Studies have shown that this suppression starts with doses as low as 5mg.
Please bear in mind though, that lung infection is actually pretty rare in cats and when present, is usually the result of an undiagnosed underlying respiratory disease such as Asthma or Bronchitis. These inflammatory conditions clog the lungs with mucus and sometimes, bacteria normally filtered out in a healthy patient, becomes trapped. It is therefore crucial that once an infection has been treated, that the inflammatory process is halted with aggressive therapy which can be tapered down as symptoms improve. Untreated inflammation can permanently damage the lungs and left unchecked, leads to scar tissue and damage to the small airway branches so therefore, the longer the problem is left, the more long term problems the patient is likely to have. The good news is that many cats are very well controlled with various drugs and do go on to lead happy and healthy lives.