Feline asthma and lower airway disease
Feline allergic asthma, Feline lower airway disease (FLAD), Feline chronic bronchial disease, Feline chronic bronchitis, Allergic bronchitis in cats, Asthma in cats
Feline asthma means the small breathing tubes deep in your cat's lungs become inflamed (swollen and irritated) and squeeze shut, so air cannot move easily. The most common sign is a dry, repeated cough where the cat crouches low with the neck stretched out and the head down - it looks exactly like trying to bring up a hairball, except nothing comes up. Other cats wheeze, breathe fast while resting, or get winded easily. This is a treatable, manageable disease and most cats do well for years, but it needs a real diagnosis first, because heartworm, lungworm and heart disease can look identical and are treated completely differently. Most cats are managed with an inhaled steroid given through a small mask and spacer made for cats, plus a rescue inhaler for bad days. If your cat is ever breathing with its mouth open, that is an emergency - go now, do not wait.
What you might notice
- A dry, repeated cough where your cat crouches low, stretches the neck out and points the head down - it looks just like trying to bring up a hairball, but nothing comes up
- A wheeze: a soft whistle or squeak you can hear when your cat breathes out, sometimes only after activity
- Breathing fast while resting or asleep - a settled healthy cat usually breathes about 20 times a minute and almost always under 30
- Open-mouth breathing or panting; healthy cats do not pant like dogs, so this always means something is wrong
- Getting winded easily: stopping partway up the stairs, or needing to rest after a short play session
- Episodes that come and go, with completely normal spells in between - many owners only notice a pattern after months
- Coughing fits set off by a trigger: cigarette smoke, dusty or scented cat litter, aerosol sprays, perfume, cleaning products, fireplace or incense smoke
- A gag or retch at the end of a coughing fit, which is often the reason the cough gets written off as a hairball problem
Standard of care
Confirm it is inflammatory lower airway disease and exclude the preventable, curable and lethal look-alikes FIRST - before any long-term steroid
Approved / guideline-backedFull physical exam and resting respiratory rate from a home video; three-view thoracic radiographs; heartworm antigen and antibody; Baermann faecal for Aelurostrongylus abstrusus; cardiac auscultation, NT-proBNP and echocardiography; then bronchoalveolar lavage for cytology, culture and Mycoplasma PCR to establish whether the inflammation is eosinophilic (asthma) or neutrophilic (chronic bronchitis). Add paired inspiratory/expiratory CT where available. A cat given lifelong steroids for 'asthma' that is actually heartworm, lungworm, cardiac disease or neoplasia has been mismanaged, not treated.
Named products: No therapeutic drug at this step. Heartworm preventive (macrocyclic lactone, product and licensure varies by market) belongs here as prevention and as part of the rule-out logic, not as asthma therapy.
Signalment, single clinical signs, haematology and radiographs cannot differentiate feline asthma from feline chronic bronchitis in 97 cats - the authors' explicit conclusion. Blood eosinophilia was the only significant discriminator (40% vs 27%, P=0.026). Heartworm and asthma overlap clinicopathologically but diverge in cause, treatment and prognosis, and feline heartworm disease is 'often under-recognized'.
Emergency stabilisation of the cat in respiratory distress - oxygen, minimal handling, inhaled bronchodilator, parenteral fast-acting glucocorticoid
Approved / guideline-backedOxygen by cage or flow-by. Minimal restraint - a struggling dyspnoeic cat can be killed by the physical examination, so stabilise before you investigate. Inhaled short-acting beta-2 agonist (albuterol/salbutamol 100 microgram metered dose, delivered through a feline spacer and mask, repeated as needed) is the practical rescue; injectable terbutaline is used where an inhaler cannot be applied. Add a rapid-acting parenteral glucocorticoid. Defer radiographs, blood draws and bronchoalveolar lavage until the cat can tolerate them.
Named products: Albuterol (salbutamol) 100 microgram/actuation human MDI via feline spacer and mask - OFF-LABEL, no NADA. Terbutaline injectable - OFF-LABEL, no NADA. Dexamethasone sodium phosphate or prednisolone sodium succinate injectable - OFF-LABEL. No FDA-approved or EMA-authorised product for feline asthma was located in this search (2026-09-12); this is an open verification item, not a settled negative.
HONEST TIER NOTE: this step is graded 1 because it is uniform, standard-of-practice care described in the peer-reviewed review literature - NOT because a regulator approved it and NOT because a controlled trial exists. No randomised trial of emergency management of feline asthmatic crisis was located, no product is approved for this indication in any jurisdiction we searched, and every drug named here is used off-label from a human label. The review literature is explicit that treatment is inhaled corticosteroids often combined with bronchodilators.
Glucocorticoids are the therapeutic backbone, and the inhaled route is the preferred long-term choice - to limit systemic exposure, not because inhalers have been proven superior
Controlled trial in this speciesInhaled fluticasone propionate via a feline spacer and mask is the usual maintenance choice. Dose-finding in an induced model found 44, 110 and 220 microgram q12h reduced airway eosinophilia by 74%, 82% and 81% respectively with NO difference between doses and NO hypothalamic-pituitary-adrenal axis suppression at any dose, and the authors concluded 44 microgram q12h is the dose that should be evaluated in naturally occurring disease. Inhaled budesonide 400 microgram q12h is the alternative with the largest naturally occurring case series. Oral prednisolone (never prednisone - see safety) is used for induction, for cats that will not accept a mask, and as a 7-day overlap at the start of inhaled therapy. Bank on 8 weeks to judge response.
Named products: Fluticasone propionate MDI 44/110/220 microgram per actuation (human product, e.g. Flovent HFA) - OFF-LABEL in cats, no NADA located. Budesonide inhaler 400 microgram q12h - OFF-LABEL. Prednisolone oral - OFF-LABEL for this indication. All require a feline spacer/mask device for the inhaled route. No animal-drug approval number can be published for any of these in feline asthma.
IN NATURALLY OCCURRING DISEASE: 9 cats with asthma randomised to oral glucocorticoid (n=4) or inhaled fluticasone (n=5) with a 7-day oral overlap at the start; at 8 weeks ALL cats were clinically normal with significantly improved airway eosinophilia and decreased nucleated cell count, fructosamine did not change, and radiographic changes did NOT improve with either therapy (PMID 33390654, n=9 - a pilot, not a definitive trial). Inhaled budesonide 400 microgram q12h in 43 owner-reported cats: the 23 still on therapy improved clinically, and 19 re-evaluated cats had significantly better barometric whole-body plethysmography (basal PENH P=0.048, PCPenh300 P=0.049) - but 20 of 43 owners had stopped the therapy on their own, and HPA axis suppression was detected in 3 of 15 tested (PMID 24000786). IN THE INDUCED MODEL: fluticasone 44/110/220 microgram q12h reduced airway eosinophilia 74/82/81% with no HPA suppression (PMID 19647461); high-dose fluticasone, alone or with salmeterol, inhibited allergen-induced airway hyper-responsiveness (all three steroid arms P<0.05) in a 6-cat crossover (PMID 21354836). INDEPENDENT APPRAISAL - quote this caveat alongside any of the above: an RCVS Knowledge Veterinary Evidence knowledge summary appraising three prospective randomised trials graded the strength of evidence as WEAK and concluded there is 'weak evidence to suggest equal treatment efficacy of oral and inhaled glucocorticoid therapy', with higher-powered studies needed before a definitive recommendation (PMID 42004677).
Bronchodilators are adjunct and rescue therapy - never monotherapy, because they open the airway without touching the inflammation
Controlled trial in this speciesInhaled short-acting albuterol/salbutamol for acute flares and as a rescue inhaler the owner keeps at home, with the owner instructed to log every use. A long-acting beta-2 agonist (salmeterol) may be combined with an inhaled steroid in cats needing more control - but only alongside a steroid, never instead of one. Rising rescue-inhaler use is the single most actionable early warning that control is being lost.
Named products: Albuterol (salbutamol) MDI 100 microgram/actuation - OFF-LABEL. Salmeterol 50 microgram/actuation, or a fluticasone/salmeterol combination inhaler - OFF-LABEL. Terbutaline injectable for in-clinic rescue - OFF-LABEL. No approved veterinary bronchodilator for feline asthma was located.
In a 6-cat randomised crossover in experimentally induced acute asthma, allergen-induced airway hyper-responsiveness was significantly inhibited by all three steroid-containing arms (P<0.05), and mean BALF eosinophil percentage fell significantly in the prednisolone and the fluticasone/salmeterol combination arms - the authors' framing is that high-dose fluticasone 'particularly in combination with' salmeterol ameliorated inflammation and hyper-responsiveness in this model. LIMITS TO STATE PLAINLY: n=6, experimentally induced disease, 4-day treatment, and the combination arm cannot be separated from its steroid component. No trial of bronchodilator monotherapy in naturally occurring feline asthma was located, and there is no evidence that a bronchodilator alone modifies the disease.
Environmental control, smoke elimination, dust-free litter and weight management - low risk, mechanistically sound, and not proven by a trial in cats
Approved / guideline-backedRemove tobacco smoke entirely from the household. Switch to a low-dust, unscented litter and avoid clay dust clouds at the box. Stop aerosol sprays, air fresheners, scented candles, incense and powdered carpet products in the cat's air space. Use HEPA filtration and manage humidity. Keep the cat lean, because a heavier cat has less respiratory reserve for a flare. Do all of this in parallel with drug therapy, never instead of it.
Named products: No drug at this step.
HONEST STATEMENT OF THE EVIDENCE GAP: no controlled trial of environmental modification in cats with asthma was located. The rationale is that the trigger for many feline bronchiolar disorders is environmental, and that because humans share that environment and have similar susceptibility, feline small-airway disease has genuine One Health relevance - which is a mechanistic and epidemiological argument, not trial evidence. Related finding, for context only and NOT an owner intervention: chronic neonatal aerosol exposure to Bermuda grass allergen tolerised kittens rather than sensitising them, the first evidence that a neonatal intervention could potentially prevent allergic asthma in cats - this was done in purpose-bred kittens of asthmatic queens and must not be presented as a reason to expose a pet kitten to anything.
Allergen-specific immunotherapy - real in-species signal, but only in purpose-bred cats with induced disease, and the sequencing with steroids matters
Early evidenceRush immunotherapy escalates allergen doses over about 24 hours followed by weekly maintenance, delivered subcutaneously or intranasally. It is the only approach studied in cats that targets the underlying hypersensitivity rather than suppressing its consequences. It should be considered a referral-level option offered with an explicit statement that no cat with naturally occurring asthma has been enrolled in a published immunotherapy trial.
Named products: Allergen extracts compounded for the individual cat's sensitisation profile. No approved feline allergen immunotherapy product for asthma was located. Dosing in the published protocols escalated 20-200 microgram Bermuda grass allergen over 24 hours with 200 microgram weekly maintenance - a research protocol, not a label.
In 12 cats sensitised to Bermuda grass allergen, BALF eosinophils fell from 62 +/- 12% to 9 +/- 4% at month 6 with subcutaneous rush immunotherapy and from 54 +/- 9% to 14 +/- 6% with intranasal; more adverse events occurred with subcutaneous (12) than intranasal (6) delivery, but only the subcutaneous protocol avoided life-threatening adverse events and gave more consistent resolution of clinical signs (PMID 19144412). Cross-protection was demonstrated when the immunotherapy allergen did not fully match the sensitising allergen (P<0.001; in dually sensitised cats single-allergen immunotherapy but not placebo reduced airway eosinophilia, P=0.038) (PMID 21937250). CRITICAL SEQUENCING FINDING: in cats receiving immunotherapy, BALF eosinophils rose significantly over time between months 6 and 9 only in the group started on an ORAL glucocorticoid (P=0.031), leading the authors to conclude inhaled glucocorticoids might be better for dampening inflammation until immunotherapy normalises the immune system (PMID 23434218). ALL of this is experimentally induced asthma in purpose-bred research cats.
Steroid-sparing second line for refractory cats, or cats in whom steroids are contraindicated - each option rests on one small in-species study, and none is proven in naturally occurring disease
Early evidenceReserve these for cats that remain symptomatic on optimised inhaled steroid plus bronchodilator plus environmental control, or for cats with concurrent diabetes or cardiac disease in whom systemic steroid exposure must be minimised. Nebulised lidocaine 2 mg/kg q8h is an adjunct only. Oral masitinib has a single supportive feline study. Ciclosporin is listed in the current review as an option supported by limited studies. Present every one of these to the owner as a trial with a defined stop date and a defined success measure, not as an established therapy.
Named products: Lidocaine 2% preservative-free for nebulisation, 2 mg/kg q8h - OFF-LABEL, research dosing. Masitinib (Masivet/Kinavet, authorised in DOGS for mast cell tumour, NOT for cats and NOT for asthma) 50 mg/day PO - OFF-LABEL cross-species use, and the feline safety database for chronic use is thin. Ciclosporin (an oral solution is approved for feline allergic dermatitis in some markets) - OFF-LABEL for asthma.
NEBULISED LIDOCAINE: in a crossover trial of 5 healthy and 9 experimentally asthmatic research cats, 2 weeks of nebulised lidocaine 2 mg/kg q8h increased the methacholine dose needed to raise airway resistance 200% (10 +/- 2 vs 5 +/- 1 mg/mL, P=0.043) but did NOT reduce BALF eosinophilia (36 +/- 10% lidocaine vs 33 +/- 6% placebo) - the authors state it is therefore 'unsuitable for monotherapy' and may serve only as adjunctive therapy; it was well tolerated and did not induce inflammation or hyper-responsiveness in healthy cats (PMID 23392613). MASITINIB: in 12 cats with induced chronic asthma, 4 weeks of oral masitinib 50 mg/day lowered BALF eosinophils to 7 +/- 9% versus 30 +/- 27% in controls (P=0.023) and improved plateau pressure (P=0.033) - but READ THE METHODS: one-tailed significance was set at P<0.1, which is a substantially weaker threshold than conventional, and BALF allergen-specific IgE was unaffected (PMID 22487554). CICLOSPORIN: named as an additional option 'mostly supported by limited studies' in the 2026 review (PMID 42320919); no controlled feline asthma trial of ciclosporin was retrieved in this search.
What NOT to do - four interventions to actively decline, three of them because in-species studies are negative
No evidence located(1) Do not use maropitant for feline asthma, acutely or chronically. (2) Do not reach for long-acting depot injectable glucocorticoid (methylprednisolone acetate) as a convenience option in an asthmatic cat. (3) Do not use dexamethasone as the routine chronic oral steroid where prednisolone will do. (4) Do not start antibiotics because a Mycoplasma PCR came back positive, absent supportive cytology and clinical picture.
Named products: Maropitant citrate (Cerenia, FDA-approved in cats for vomiting - NOT for airway disease): declined for this indication on the basis of two negative in-species trials. Methylprednisolone acetate (Depo-Medrol): avoid in asthmatic cats. Dexamethasone: not the routine chronic oral choice in cats.
MAROPITANT IS NEGATIVE TWICE OVER, IN CATS. Chronic dosing (2 mg/kg PO q48h for 4 weeks, randomised placebo-controlled crossover, 6 induced-asthma cats) produced no significant difference versus placebo in clinical scoring (P=0.589 and P=1.0), airway hyper-responsiveness (P=0.818) or airway eosinophilia (P=0.669); the authors state it 'cannot be recommended as a novel treatment for this disorder' (PMID 25964466). A single 2 mg/kg SC dose given immediately post-allergen challenge in 7 cats failed on clinical composite score (P=0.902), visual analogue scale (P=0.710), AHR (P=0.456) and airway eosinophilia (P=0.165), and 'cannot be recommended as treatment for feline status asthmaticus' (PMID 25964467). DEPOT STEROID: methylprednisolone acetate 5 mg/kg IM in 12 cats caused a substantial rise in serum glucose and expanded plasma volume by 13.4%, exceeding 40% in 3 of the 12 cats, by an intra- to extracellular fluid shift secondary to glucocorticoid-mediated hyperglycaemia - the authors conclude this may predispose cats with any cardiovascular disorder to congestive heart failure (PMID 16579749). DEXAMETHASONE: 0.55 mg/kg/day PO versus clinically equipotent prednisolone 4.4 mg/kg/day for 56 days in 14 cats produced significantly more glucosuria in the dexamethasone group (P=0.027) with trends toward higher fructosamine and reduced insulin sensitivity - dexamethasone is the more diabetogenic of the two in cats (PMID 19723844). MYCOPLASMA: M. felis was detected by PCR in BALF of 4 of 9 control cats WITHOUT respiratory signs versus 6 of 17 cats with asthma or bronchitis (P=0.6924), and the authors raise the possibility that Mycoplasma species are commensals of the feline lower respiratory tract (PMID 24574148).
Feline Asthma - Update on Diagnosis and Treatment Recommendations (current reference review). THERE IS NO CONSENSUS GUIDELINE FOR THIS DISEASE. — Veterinary Clinics of North America: Small Animal Practice - a peer-reviewed clinical review, NOT a consensus guideline. NO ISFM, AAFP, ACVIM or ECVIM consensus guideline for feline asthma or feline lower airway disease was located in this search (2026-09-12), and PetSmartMeds must not cite one. The closest thing to independent evidence grading is an RCVS Knowledge Veterinary Evidence knowledge summary, which appraised three prospective randomised trials of inhaled versus oral glucocorticoid in feline asthma and graded the strength of evidence as WEAK, concluding only that there is 'weak evidence to suggest equal treatment efficacy of oral and inhaled glucocorticoid therapy' and that higher-powered studies are required before a definitive recommendation can be made. Where a feline drug-safety question arises in this protocol - NSAIDs, comorbid chronic kidney disease, analgesia - the governing document is the 2024 ISFM and AAFP consensus guidelines on the long-term use of NSAIDs in cats (Taylor S, et al. J Feline Med Surg. 2024;26(4). PMID 38587872. DOI 10.1177/1098612X241241951), which is a real consensus guideline but is not about airway disease.
How it is diagnosed
- History plus an owner-recorded phone video of an actual episode. This one step changes management more than any other, because the crouched-neck-extended cough is visually distinctive and owners almost always describe it as vomiting or hairballs. Ask the owner to film the cat breathing at rest at home as well - respiratory rate in the consultation room is uninterpretable (median 64 breaths/min in clinically healthy cats, reference interval 32-135) whereas the same cats at home had a median resting rate of 27 and sleeping rate of 20 (PMID 29680402).
- Thoracic radiographs, ideally three views. Expect a bronchial or bronchointerstitial pattern, lung hyperinflation, and in some cats right middle lung lobe collapse. Two hard limits: radiographs were abnormal in 94% of asthma and 91% of chronic bronchitis cats and could NOT distinguish them (PMID 31483195), and thoracic radiography has low utility for detecting small-airway (bronchiolar) disease at all (PMID 30982233). Normal films do not exclude the disease, and abnormal films do not confirm it.
- Heartworm antigen AND antibody testing plus a Baermann faecal for Aelurostrongylus abstrusus, in every coughing cat, before committing to lifelong steroids. Heartworm-associated respiratory disease (HARD) and asthma share bronchial radiographic patterns, eosinophilia and clinical signs, but differ in cause, progression, treatment and prognosis - and HARD is preventable while asthma is not (PMID 31446863).
- Cardiac assessment before steroids: auscultation, NT-proBNP and ideally echocardiography. Dyspnoea in a cat is cardiac until proven otherwise, and systemic glucocorticoids expand plasma volume in cats (PMID 16579749, PMID 31816124) - so an occult cardiomyopathy found after the steroid starts is the worst possible sequence.
- Bronchoalveolar lavage with cytology, total and differential cell counts, aerobic culture with quantitative interpretation, and Mycoplasma PCR. This is the defining test: eosinophilic inflammation defines asthma, neutrophilic defines chronic bronchitis. Bronchoscopic appearance alone is useless for the distinction - excess mucus (83%), bronchial stenosis and nodular epithelial irregularity (56%), hyperaemia (54%), airway collapse (48%) and bronchiectasis (27%) occurred across asthma, pneumonia and neoplasia with no differentiating features (PMID 21314731). Interpret Mycoplasma PCR cautiously: M. felis was recovered from BALF of 4 of 9 sick cats with NO respiratory signs versus 6 of 17 cats with asthma or bronchitis, a non-significant difference (P=0.6924) (PMID 24574148).
- Disclose and plan for the risk of the diagnostic itself. General anaesthesia and bronchoalveolar lavage have precipitated bronchospasm severe enough to cause inability to ventilate and cardiac arrest in an asthmatic cat (PMID 26331417). Pre-oxygenate, have a bronchodilator drawn up, keep the procedure short, and refer if the cat is unstable.
- Computed tomography with PAIRED inspiratory and expiratory scans where available - it is the imaging modality able to detect pathology centred on the small airways that radiographs miss, and it is what the proposed feline bronchiolar-disorder classification is built on (PMID 30982233).
- Allergy testing is optional, interpret it narrowly. In the only randomised trial in naturally occurring feline asthma, 50% of cats tested positive for allergen-specific IgE (PMID 33390654). A positive serum IgE panel identifies sensitisation, not causation, and does not by itself justify treatment.
Where a biologic fits
Our own product, graded by the same rule
There is no legitimate role for mesenchymal stem cell, exosome or peptide products in feline asthma or feline lower airway disease, and PetSmartMeds will not offer them for this condition: the only published cell-therapy studies were done in purpose-bred cats with experimentally induced asthma, the study that tested the clinically relevant scenario of treating disease that was already established failed to reduce either airway inflammation or airway hyper-responsiveness and its imaging benefit was gone by 12 months, no cat with naturally occurring asthma has ever been treated in a published trial, and no exosome or peptide product has any efficacy evidence in this species at all - while inhaled corticosteroids, which do work, are cheap, well tolerated and available today.
What exists
TWO MESENCHYMAL STROMAL CELL STUDIES EXIST IN CATS, BOTH IN EXPERIMENTALLY INDUCED (BERMUDA GRASS ALLERGEN) ASTHMA IN PURPOSE-BRED RESEARCH CATS, BOTH FROM THE SAME GROUP. (1) CHRONIC, ALREADY-ESTABLISHED DISEASE - the clinically relevant scenario, and it FAILED. Cats with chronic experimentally induced asthma received six intravenous infusions of allogeneic adipose-derived MSC (0.36-2.5 x 10^7 cells per infusion) or placebo bimonthly, followed for 1 year. Verbatim result: 'There were no differences between treatment groups or over time with respect to airway eosinophilia or AHR.' The only positive findings were lower CT lung attenuation (P=0.0311) and bronchial wall thickening (P=0.0489) scores at month 8 - and those were NOT sustained at month 12. No differences in allergen-specific IgE, cellular IL-10 production or allergen-specific lymphocyte proliferation. Authors' own conclusion, verbatim: 'When administered after development of chronic allergic feline asthma, MSCs failed to reduce airway inflammation and AHR.' [Trzil et al. 2014, PMID 25220646] (2) ACUTELY INDUCED DISEASE - n=4 treated versus n=2 placebo. Five IV infusions of allogeneic cryopreserved adipose MSC (2 x 10^6, 4 x 10^6, 4.7 x 10^6, 1 x 10^7, 1 x 10^7 per cat) over 130 days, plus separate imaging control groups of 4 untreated asthmatic and 6 healthy cats, followed 9 months. Early airway eosinophilia was NOT affected and was numerically WORSE in treated cats (post-treatment average 41 +/- 15% MSC vs 34 +/- 16% placebo). By month 9, eosinophil percentages in all MSC-treated cats had fallen into the normal reference interval (MSC 6%, placebo 20%, normal <17%), airway hyper-responsiveness was diminished at day 133, and CT lung attenuation (-865 +/- 12 HU vs -820 +/- 11 HU untreated asthmatic, P=0.004) and bronchial wall thickening score (0 [0-1.5] vs 11.6 [7.3-27.3], P=0.010) were significantly better at month 9. The authors state 'no clear immunologic mechanisms by which MSCs act were determined' and that results 'warrant additional investigation.' At n=4 versus n=2 no inferential statistic is meaningful. [Trzil et al. 2016, PMID 26384398] CONTEXT FROM ADJACENT SPECIES AND INDICATIONS, LABELLED AS SUCH: the only regulator-authorised MSC product for a companion-animal indication is DogStem (EMA EMEA/V/C/005829), which uses EQUINE umbilical-cord MSC in DOGS - a xenogeneic product - for canine osteoarthritis, reporting 51% of treated dogs versus 5% of placebo meeting a force-plate gait endpoint at 8 weeks. That is a different species, a different organ and a different disease, and it says nothing about feline airways. Equally, the claim that these cells are 'immune-privileged' is NOT defensible: Punzon et al. found that BOTH equine and canine MSC RAISED ANTIBODY TITRES in dogs, although safety was nonetheless acceptable (Front Vet Sci 2023;10:1098029, PMID 37266387). PetSmartMeds must never describe these products as immune-invisible.
What has not been shown
ZERO CATS WITH NATURALLY OCCURRING ASTHMA HAVE BEEN TREATED WITH MSC, EXOSOMES OR PEPTIDES IN ANY PUBLISHED TRIAL. Everything above is an induced laboratory model in purpose-bred cats. NO EXOSOME OR EXTRACELLULAR-VESICLE PRODUCT has any published in-vivo clinical efficacy evidence in feline airway disease - a PubMed search for exosome/extracellular vesicle combined with feline airway disease and asthma returned ZERO records (run 2026-09-12), consistent with the broader finding that exosome/EV products have no published in-vivo clinical efficacy evidence in dogs or cats for any indication. NO PEPTIDE has controlled efficacy evidence for feline asthma, or for any feline indication. BPC-157 returns zero feline PubMed records. The entire 'thymosin beta 4 / TB-500 in cats' literature consists of two 1983 biochemistry papers on the tissue distribution of the ENDOGENOUS peptide across vertebrate species (PMID 6838210; PMID 6578703) - that is comparative biochemistry, not therapy, and TB-500 is additionally banned by the FEI. KPV, LL-37, GHK-Cu and vasoactive intestinal peptide have no feline clinical data; VIP has an airway mechanistic rationale only, and aviptadil holds no FDA approval. NO CELL OR EXOSOME PRODUCT IS FDA-APPROVED FOR ANY ANIMAL SPECIES. In the United States these are unapproved new animal drugs. There is no EMA-authorised stem cell product for dogs or cats at all. AND THE MOST IMPORTANT ABSENCE OF ALL: there is no evidence that any biologic modifies airway eosinophilia, airway hyper-responsiveness, cough frequency, rescue-inhaler use, steroid dose or survival in a pet cat with asthma. Offering one in place of, or before, a diagnostic bronchoalveolar lavage and an inhaled corticosteroid would delay effective, inexpensive, well-tolerated therapy in a disease whose prognosis with conventional treatment is described as good to excellent.
Sources
- MSC in CHRONIC induced feline asthma - THE NEGATIVE TRIAL, and the one that matters clinically — Trzil JE, Masseau I, Webb TL, Chang C-H, Dodam JR, Cohn LA, Liu H, Quimby JM, Dow SW, Reinero CR. Long-term evaluation of mesenchymal stem cell therapy in a feline model of chronic allergic asthma. Clin Exp Allergy. 2014;44(12):1546-57. PMID 25220646. DOI 10.1111/cea.12411 (PMC4247171). NIH-funded. Null on airway eosinophilia and airway hyper-responsiveness; CT remodelling benefit at month 8 not sustained at month 12; group sizes are not stated in the abstract. https://doi.org/10.1111/cea.12411
- MSC in ACUTELY induced feline asthma - the pilot, n=4 treated vs n=2 placebo — Trzil JE, Masseau I, Webb TL, Chang C-H, Dodam JR, Liu H, Quimby JM, Dow SW, Reinero CR. Intravenous adipose-derived mesenchymal stem cell therapy for the treatment of feline asthma: a pilot study. J Feline Med Surg. 2016;18(12):981-990. PMID 26384398. DOI 10.1177/1098612X15604351. No early effect on airway eosinophilia (numerically worse in treated cats); delayed normalisation of eosinophil percentage and improved CT remodelling scores at month 9; mechanism undetermined. https://doi.org/10.1177/1098612X15604351
- Feline MSC clinical-trial landscape - which feline indications actually have trial data — Quimby JM, Borjesson DL. Mesenchymal stem cell therapy in cats: Current knowledge and future potential. J Feline Med Surg. 2018;20(3):208-216. PMID 29478398. DOI 10.1177/1098612X18758590. Feline MSC clinical-trial data exist for gingivostomatitis, chronic enteropathy, asthma and kidney disease - and only the first two are positive. https://doi.org/10.1177/1098612X18758590
- 'Immune-privileged' is NOT a defensible claim - MSC raised antibody titres in dogs — Punzon E, et al. Front Vet Sci. 2023;10:1098029. PMID 37266387. Both equine and canine mesenchymal stromal cells raised antibody titres in dogs; safety was nonetheless acceptable. Never publish that these products are immune-invisible. https://doi.org/10.3389/fvets.2023.1098029
- The one authorised companion-animal MSC product - equine cells, in DOGS, for osteoarthritis (not cats, not airways) — DogStem, EMA EMEA/V/C/005829. Xenogeneic equine umbilical-cord-derived MSC authorised for canine osteoarthritis; 51% of treated dogs versus 5% of placebo met a force-plate gait endpoint at 8 weeks. Cited here only to mark the boundary of what is authorised - it has no bearing on feline asthma. https://www.ema.europa.eu/en/medicines/veterinary/EPAR/dogstem
- Effective conventional therapy exists - which is why an unproven biologic here causes harm by delay — Verschoor-Kirss M, Rozanski EA, Sharp CR, Oura TJ, Egan A, Bain P, Knoll J. Treatment of naturally occurring asthma with inhaled fluticasone or oral prednisolone: A randomized pilot trial. Can J Vet Res. 2021;85(1):61-67. PMID 33390654 (PMC7747657). All 9 cats were clinically normal after 8 weeks with significantly improved airway eosinophilia on either route. https://pmc.ncbi.nlm.nih.gov/articles/PMC7747657/
- Prognosis with conventional treatment is good to excellent - the bar any biologic would have to clear — Garrity S, Lee-Fowler T, Reinero C. Feline asthma and heartworm disease: Clinical features, diagnostics and therapeutics. J Feline Med Surg. 2019;21(9):825-834. PMID 31446863. DOI 10.1177/1098612X18823348. 'In asthma, morbidity is relatively high, but mortality is low, with an overall good to excellent prognosis.' https://doi.org/10.1177/1098612X18823348
- Thymosin beta 4 in cats is 1983 comparative biochemistry, not therapy - the honest basis for 'no peptide evidence' — Erickson-Viitanen S, Ruggieri S, Natalini P, Horecker BL. Distribution of thymosin beta 4 in vertebrate classes. Arch Biochem Biophys. 1983;221(2):570-6. PMID 6838210. DOI 10.1016/0003-9861(83)90177-7; and Thymosin beta 10, a new analog of thymosin beta 4 in mammalian tissues. Arch Biochem Biophys. 1983;225(2):407-13. PMID 6578703. DOI 10.1016/0003-9861(83)90047-4. These are tissue-distribution studies of the endogenous peptide that happen to include cat spleen. They are not evidence for TB-500 as a therapy in any species. https://doi.org/10.1016/0003-9861(83)90177-7
Tracking response
How you know whether it is working
STATE THIS PLAINLY: there is NO validated, licensed, owner-completed clinical metrology instrument for feline asthma. We searched and did not find one (2026-09-12), and PetSmartMeds must never imply a validated feline asthma score exists. What we use instead is a three-part composite, each part of which is defensible on its own terms. (1) HOME RESTING AND SLEEPING RESPIRATORY RATE, counted by the owner and logged - the only quantitative, reference-anchored, zero-cost, zero-risk measure available for this disease. (2) A CLIENT-SPECIFIC OUTCOME MEASURE (CSOM) style set of owner-nominated items: coughing episodes per week, rescue-inhaler actuations per week, and one activity the owner's own cat currently struggles with. CSOM is a method rather than a copyrighted item list, so it can be implemented without licensing anything. (3) VETERINARIAN-SIDE OBJECTIVE RE-STAGING where the clinical question justifies it: repeat bronchoalveolar lavage cytology, and thoracic imaging - but note that radiographic changes did NOT improve after successful treatment with either inhaled or oral glucocorticoid in the only randomised trial in naturally occurring disease, so imaging is a poor treatment-response endpoint in this condition.
RESPIRATORY RATE REFERENCE VALUES: Dijkstra E, Teske E, Szatmari V. Respiratory rate of clinically healthy cats measured in veterinary consultation rooms. Vet J. 2018;234:96-101. PMID 29680402. DOI 10.1016/j.tvjl.2018.02.014. In 88 clinically healthy adult cats, respiratory rate in the consultation room ranged 28-176 breaths/min (median 64, calculated reference interval 32-135), whereas from owner-made home video recordings of the SAME cats the resting rate was median 27 (range 16-60, n=32) and the sleeping rate median 20 (range 9-28, n=38), both significantly lower (P<0.0001 each). The authors conclude that textbook reference intervals reflect resting rate AT HOME, that clinic-derived values would erroneously label many cats tachypnoeic, and that 'owners should be encouraged to film their pets before they visit their veterinarian'. TWO CAVEATS TO CARRY WITH IT. First, these are reference values established in HEALTHY cats; they have not been validated as a severity or treatment-response outcome measure in feline asthma, and we must not present them as one. Second, clinical signs alone cannot even separate feline asthma from feline chronic bronchitis - cough was reported in 95% versus 96% and dyspnoea in 73% versus 79% of the two groups, all non-significant (Grotheer M, et al. J Feline Med Surg. 2020;22(7):649-655. PMID 31483195. DOI 10.1177/1098612X19872428) - so an owner-reported score tracks how the cat is doing, never what the cat has. WHY IMAGING IS NOT THE ENDPOINT: in 9 cats with naturally occurring asthma made clinically normal at 8 weeks with significantly improved airway eosinophilia, 'no improvement was seen in radiographic changes after treatment with either therapy' (Verschoor-Kirss M, et al. Can J Vet Res. 2021;85(1):61-67. PMID 33390654). WHY ADHERENCE MUST BE MEASURED: of 43 cats prescribed inhaled budesonide, owners had withdrawn therapy in 20 of them by the time of follow-up contact (Galler A, et al. J Small Anim Pract. 2013;54(10):531-6. PMID 24000786. DOI 10.1111/jsap.12133). Roughly half of prescriptions stopped on their own is the single biggest determinant of outcome in this disease, and only a check-in system will catch it.
Suggested cadence: BASELINE, BEFORE THE FIRST DOSE: seven consecutive days of owner-counted sleeping respiratory rate; a seven-day cough-episode count; body weight and body condition score; the owner's three nominated CSOM items; and - if any systemic glucocorticoid is planned - blood glucose, fructosamine, blood pressure, and cardiac screening with auscultation, NT-proBNP and ideally echocardiography. FIRST REASSESSMENT AT 2-4 WEEKS to catch technique failure, mask refusal and early adverse effects; this is a process check, not an efficacy verdict. EFFICACY VERDICT AT 8 WEEKS. Both studies in naturally occurring disease read out at that horizon - the randomised pilot evaluated cats at baseline and 8 weeks (PMID 33390654) and the budesonide series re-evaluated cats still on therapy after more than 2 months (PMID 24000786) - so 8 weeks is the honest window in which to judge whether an inhaled steroid is working. Do not declare failure at 2 weeks and do not let a non-responder drift for 6 months. ONCE STABLE: owner respiratory-rate log and cough/rescue-puff counts every 4 weeks through the check-in system; veterinary recheck with weight and auscultation every 3 months; glucose, fructosamine and blood pressure at every recheck while any systemic steroid is being given, and at least every 6 months on inhaled therapy alone; heartworm prevention and testing reviewed annually. TRIGGER AN UNSCHEDULED VISIT ON ANY OF: sleeping respiratory rate above 30 on two consecutive nights, rescue inhaler use rising week on week, a new nocturnal cough, weight loss, or new polyuria and polydipsia. RE-OPEN THE DIAGNOSIS rather than escalating the steroid in any cat that fails to respond by 8 weeks - the commonest reason a feline 'asthmatic' does not respond to a steroid is that it does not have asthma.
Questions you can answer at home
- While your cat was sound asleep, how many breaths did you count in one minute? (Count the chest rises for 30 seconds and double it. A settled healthy cat is usually around 20 and almost always under 30. Two nights in a row above 30 means call us.)
- How many coughing episodes did your cat have in the last 7 days? (An episode is one bout of that crouched, neck-stretched-out coughing - count bouts, not individual coughs.)
- How many times did you need to use the rescue inhaler in the last 7 days, and was that more, less, or the same as the week before?
- Since the last check-in, has your cat had ANY episode of breathing with its mouth open, or breathing hard with the belly heaving? (If yes, tell us even if it passed quickly.)
- Be honest with us: did your cat get every scheduled dose of the inhaler, or were doses missed or stopped? (In one study, owners had stopped the inhaler in 20 of 43 cats. Nobody is in trouble - we just cannot help if we do not know.)
- Is your cat jumping, playing, eating and keeping weight on as well as at the last check-in - and is there anything new in the house, like a new litter, a new cleaning product, a candle or someone smoking indoors?
Last reviewed: 2026-09-12 · Every claim on this page carries a citation you can check. If one does not hold up, tell us and we will correct it. science@azzamedical.com
Build a profile for your pet
Tell us what you are dealing with and the site will show you only what applies.