A variety of inhaled substances can have adverse affects on cats. In general, these substances are the same things that would cause problems for people. Carbon monoxide, smoke, fumes from bleach and other cleaning products, sprayed insecticides, etc. are some of the toxic substances that can be inhaled. Most of these substances irritate the airways.
For example, carbon monoxide, which is produced by car exhaust, gas appliances, kerosene heaters, etc., blocks the ability of blood to carry oxygen. This can be fatal if not treated quickly.
In the case of carbon monoxide, watch for bright red tongue, gums and other tissues inside the mouth.
Diagnosis is based primarily on the information you provide, so give your veterinarian as many details as you can. Your veterinarian will perform a thorough examination on your cat and order various tests to determine the physiological damage. This will usually include X-rays and blood tests, among other diagnostic procedures.
Your cat will likely be put on oxygen, especially if she is suffering from carbon monoxide poisoning. Medication to relieve irritation and swelling of the airways, like corticosteroids, will be used in most cases. Additional medication to help breathing or the heart may be given, as well as intravenous fluids and other supportive care.
If the irritation is severe enough, secondary infection can set in, resulting in pneumonia. This would require antibiotics and possibly hospitalization. You will want to watch for symptoms that don’t go away or that get worse. Should there be any possibility of permanent lung damage or other long-term issues, your veterinarian will inform you.
The same precautions you would take for you and your family apply to your cat as well. Keep cleaners and solvents in sealed containers in well-ventilated rooms. Don’t leave your car running in your garage. Be sure gas appliances, kerosene heaters, and fireplaces are functioning properly and well-ventilated. Equip your home with carbon monoxide detectors. Lastly, be aware of your cat's movements so that he does not get trapped in an area where he would be at risk of exposure to these poisons.