Asthma or chronic bronchial disease are rare respiratory diseases in cats.
Clinically, respiratory diseases in cats manifest themselves in coughing, wheezing, a drop in performance, and shortness of breath. They are characterized by inflammation of the lower airways without an identifiable cause. Young and middle-aged cats are most commonly affected, and the disease is found somewhat more frequently in Siamese cats.
As with asthma in humans, the exact causes in cats have not been fully elucidated. The clinical symptoms of coughing and shortness of breath can be explained by a blockage (obstruction) of the lower airways. This leads to inflammation of the bronchi and an increase in size (hypertrophy) of the bronchial muscles and mucous glands. This leads to a reduced air flow into the alveoli and clinically manifests itself in increased breathing up to and including shortness of breath.
In human medicine, allergens are known to be potential risk factors for the development and symptoms of asthma. The role of allergens in asthmatic cats is not clear; Allergy-triggering substances, air pollution and irritations in the form of aerosols can potentially aggravate the clinical symptoms and possibly also trigger the disease.
Attention should be drawn to possible allergen exposure. Allergy-causing substances can be a new (scented) cat litter, cigarette smoke, open fire, scented aerosols (carpet cleaners, room fragrances, deodorants, hairspray), increased exposure to dust (moving) or seasonal pollen count.
Cats with a chronic bronchial disease often show recurrent coughing, wheezing or shortness of breath and possible exhaustion (lethargy). The cat may exhibit a labored breathing pattern (pumping) and a prolonged exhalation phase due to the obstruction of the small lower airways causing air trapping in the alveoli.
About 20% of cats with bronchial disease show an increased level of eosinophils (a type of white blood cell) in the blood. Since other allergic or parasitic diseases (lungworms, heartworms, gastrointestinal parasites, skin parasites) can also lead to an increase in eosinophilic granulocytes, this is a non-specific finding.
A fecal examination to rule out parasites should always be carried out on a coughing cat. A 3 day fecal sample should be examined as this increases the chance of finding parasites. A negative test does not exclude the presence of parasites, since they are not always (intermittently) excreted. Recommended faecal examinations are emigration methods according to Baermann (lung worms).
The classic x-ray of a cat with chronic bronchial disease shows thickening of the bronchial walls, which can be seen in the form of circular rings (also called donuts) and tram rails. The lung field may appear enlarged by hyperinflation, causing the diaphragm to be displaced caudally (toward the tail). In some cats, the strained breathing can also lead to broken ribs, which can be seen in the x-ray.
Bronchoscopy is an examination method in which a small camera is used to examine the trachea and bronchi. Here, a washing (lavage) of the bronchi and the air sacs (alveoli) is also carried out. The liquid obtained during washing is examined cytologically and bacteriologically.
Since allergens can aggravate or trigger the clinical picture in cats, it is important to avoid potential allergens. In some cases this is not possible (e.g. pollen count), in other cases (e.g. smoking) it is feasible. In any case, it should be found out whether potential allergens are present which could have worsened the clinical picture.
In principle, there is the possibility of inhalation therapy in the treatment of cats with chronic bronchial diseases. This offers the advantage that the drug accumulates primarily in the lower respiratory tract and can therefore have a targeted effect. Another advantage is the reduction of side effects compared to systemic therapy. Corticosteroids in particular can lead to serious side effects in cats (e.g. diabetes mellitus) depending on the dose.
The aim is to get the cat used to inhalation therapy carefully and playfully. It usually makes sense to start therapy with oral medication at the beginning, while the cat can slowly get used to inhalation therapy. In most cases, chronic bronchial disease therapy is a lifelong therapy, which is why it is necessary to find the most minimal, but most effective dosage for the treatment of the disease. It makes sense to start therapy early, as the chronic cough and inflammatory stimulus can lead to a progressive deterioration in the clinical picture. If neither the administration of medication nor inhalation therapy is feasible, there is the possibility of administering steroids with a depot effect (every 2-4 weeks). This is not ideal as the dose cannot be well regulated and the risk of side effects is higher.
As previously mentioned, cat inhalation therapy is the best form of therapy, but not all cats tolerate it.
When should you contact the vet?
A cat with acute shortness of breath (mouth breathing) is an absolute emergency and requires immediate presentation to the vet as the first emergency measure. Here the cat needs oxygen for stabilization. With all cats in acute respiratory distress, it is important NOT to stress the animal.
Emergency medical treatment can initially be administered intramuscularly (rapid absorption). Drugs that are used are bronchodilators to widen the bronchi. The cat should respond to therapy (improvement in breathing pattern, pink tongue) within 30-45 minutes. If unsuccessful, a corticosteroid can be given. In very severe cases of shortness of breath that do not respond to therapy, temporary artificial ventilation with 100% oxygen must be considered.
A cat at risk of a recurring asthma attack should have emergency medication at home. A bronchodilator (terbutaline) can also be given at home in an emergency. Depending on the cat’s owner and the cat’s tolerance, the medication can be administered under the skin or through a breathing mask. If the cat does not respond to therapy within 15-30 minutes, it may require supplemental oxygen or corticosteroids and should be seen to a veterinarian immediately.