This is an article written by Dr. Danièlle Gunn-Moore, which you may wish to print off and share with your vet.
Since writing these notes, Dr. Gunn-Moore is now testing the Aerokat
feline spacer in practice.
LOCALISATION OF THE CAUSE OF DYSPNOEA
The first step in diagnosing the cause of dyspnoea is to determine if it is due to non-respiratory causes, URT disease, LRT disease or disease affecting the pleural space. This differentiation should be possible by taking a detailed history and performing a thorough physical examination (Table 1). Inspiratory dyspnoea is usually associated with URT disease resulting in airway obstruction, or pleural disease preventing full lung expansion. URT disease may be accompanied by sneezing, nasal discharge, wheezing, snoring, snorting, facial deformity, obstructed nares, or dysphagia. Laryngeal disease may cause a change in the animal’s voice. Expiratory dyspnoea is usually a sign of LRT disease. Tachypnoea (rapid breathing) or orthopnoea (dyspnoea when recumbent) do not help in localising the cause of the dyspnoea.
Acute URT disease - Cat ‘flu’
Cat ‘flu’ is the common name used to describe infectious acute URT disease. It is frequently seen in unvaccinated cats and kittens, particularly when they are kept in large groups, either in private homes, or rescue centres. While the disease can be caused by a number of different organisms, over 80% of cases are caused by infection with either feline calicivirus (FCV), or feline rhinotracheitis virus (FRV, also called feline herpes virus). Other organisms may also be involved, including feline coronavirus (FCoV), mixed bacteria; Bordetella bronchiseptica, Pasturella multocida and Mycoplasma species, and Chlamydophila felis (formerly Chlamydia psittaci). Many cases of cat ‘flu’ involve infection with a number of different organisms. Environmental factors, such as poor ventilation, high humidity, and over-crowding may exacerbate the problem.
Factors involved in cat ‘flu’:
rhinotracheitis virus (FRV)
Diagnosis of cat ‘flu’:
· A presumptive diagnosis is usually made on the presence of typical clinical signs and a history of possible exposure to causal organisms. While different organisms tend to produce characteristic changes in the laboratory situation, in mixed natural infections it is not usually possible to determine which organisms are involved from clinical signs alone. That said, FRV tends to cause more severe disease than FCV, with more prominent conjunctivitis, perfuse nasal discharge, and obvious coughing. FCV tends to be associated with milder clinical signs, and oral ulceration. Chlamydophila felis is usually associated with conjunctivitis, which may initially be unilateral. Bordetella bronchiseptica may cause coughing, and is generally seen when kittens are kept in over-crowded conditions.
· Nasal or oropharyngeal swabs can be taken for isolation and culture. Care should be taken when interpreting the results since FRV is shed only intermittently, and FCV shedding may result from infection with either pathogenic or non-pathogenic field strains of virus, or vaccine virus. Bacteriology is generally of little value unless the diagnostic laboratory is instructed to look for specific agents e.g. B. bronchiseptica, Mycoplasma spp., or C. felis. It is advisable to speak to the laboratory prior to collecting the samples since specific transport media may be required.
· Serology can be used to determine whether or not a cat has been previously exposed to FCV or FRV. However, it is of limited value since most cats have usually been vaccinated.
Treatment of cat ‘flu’:
usually involves symptomatic therapies and good nursing care.
Prevention of cat ‘flu’:
To reduce respiratory disease within a group of cats it is necessary to address infectious and non-infectious causes. This may require instigating a suitable vaccination and/or isolation programme, treating with suitable antibacterials, improving ventilation, and reducing over-crowding.
a suitable vaccination program
Causes of chronic URT disease
post-viral rhinitis / idiopathic chronic rhinitis:
/ Trauma / Oedema / Polyp / Granulomata / Neoplasia:
body / Trauma:
Stenosis / Tracheal Collapse / Neoplasia:
DIAGNOSIS OF URT DISEASE
Diagnosis of URT disease, as with all diagnostic investigations, relies on a combination of knowing the signalment of the patient (i.e. its age, sex and breed), gaining a complete medical history, performing a thorough physical examination, then undertaking selected further investigations.
The signalment can be of help since congenital detects will usually cause clinical signs within a few days of birth. However, cat ‘flu’ is seen most frequently in older kittens, and neoplasia is seen most typically in old cats. While the breed rarely has a bearing on URT disease, the author has seen nasonasal polyps most frequently in Oriental breeds of cat.
the history it is important to determine;
points to look out for include:
· The character of breathing, and whether or not the breathing is noisy when the cat breathes through its mouth, may help to localise disease to the nasal area or the larynx. Generally, the breathing is more stertorous (snoring) when disease is in the nose, but more stridorous (high pitched and harsh) when disease affects the larynx.
· Facial examination may reveal a lack of symmetry or facially swelling (most typically associated with neoplasia or fungal infections). Facial pain and resentment of facial examination is common among cats with URT obstruction, especially those with intranasal foreign bodies, or polyps. In Siamese cats the facial hair overlying the inflamed nasal chambers may become de-pigmented.
· Ocular examination should involve assessment of the periocular area, the anterior and posterior chambers, and the retina. Examination may reveal a serous ocular discharge resulting from tear duct damage associated with previous URT viral disease, or occasionally associated with cancer within the nose. Previous FCV, FRV or C. felis infections can result in chronic conjunctivitis, which in the case of FRV infection may also result in keratitis. Retinal lesions may be seen associated with intranasal neoplasia or fungal rhinitis.
· Aural examination may reveal evidence of painful or infected ears associated with inflammatory polyps.
· General body condition and body weight. Cats with URT obstruction often have a poor appetite and so experience a degree of weight loss. Marked weight loss is more suggestive of neoplasia, fungal disease or severe systemic disease.
· Cats with chronic URT disease frequently have mild to moderate submandibular lymphadenopathy. If submandibular lymphadenopathy is marked, or if lymph nodes elsewhere in the body are also affected, neoplasia or fungal infections are most likely to be the cause.
· Kidneys should be assessed for size and shape since nasal LSA may be associated with renal LSA.
Since different diseases can present very similarly it is important not to over-interpret the presence of a particular clinical sign. A few general rules usually hold true, e.g. facial deformity with associated pain, especially if accompanied by a unilateral nasal haemorrhage or marked lymphadenopathy, is usually suggestive of nasal neoplasia or fungal infection. However, a lack of these findings does not rule out these diagnoses; some cases of nasal LSA cause bilateral nasal obstruction and little nasal discharge of any kind. Also, although post-viral rhinitis usually presents with chronic bilateral purulent discharge, it can also present with unilateral discharge, sometimes blood tinged and occasionally with frank haemorrhage.
Assessment of serum biochemistry, haematology, and FeLV/FIV status will help to gain an overall picture of the cat’s health.
Attempts to make a diagnosis from nasal swabs taken from a conscious cat are rarely successful (unless C. neoformans is detected). If C. neoformans is detected its presence should be confirmed by culture and/or serology. Bacteria detected in this manner usually represent only secondary contaminants.
The detection of FRV or FCV by oro-pharyngeal swab and viral culture is rarely helpful. Vaccinated cats and cats that have been previously infected with FCV may also be shedding virus. Since FRV is shed only intermittently, failure of its detection does not negate against it playing a causal role in disease.
It is usually only by performing a detailed examination of the URT (for which the cat has to be anaesthetised), taking radiographs, and collecting samples for microbiological and histopathological examination, that a definitive diagnosis may be made. These procedures are performed under general anaesthesia; anaesthesia is induced, the mouth and larynx are examined as the cat is intubated, radiographs are taken, and then the nasopharynx and nasal chambers are examined. The investigations can be performed under the same anaesthetic. Radiographs should be taken before the introduction of flushing solutions, an endoscope, or biopsy instruments since these procedures may result in haemorrhage that will alter the radiographic appearance.
To prevent head movement radiographic investigations should be performed with the cat under general anaesthetic. When taking the radiographs it is advisable to remove the endotracheal tube to prevent it obscuring essential details.
investigation should include:
Lateral oblique view Open mouth view Intraoral views
Radiographs should be assessed for the presence of dental disease, evidence of middle ear infection, obstruction of the nasopharynx by soft tissue, soft tissue density within the frontal sinuses, loss of integrity of the nasal septum, and loss of turbinate detail. Whether the loss of turbinate detail is unilateral or bilateral, and its position within the nasal chambers may help to localise the disease. The loss of turbinate detail may be due to an overall loss of turbinate bone, or an overlying increase in soft tissue. While the nature of the change should be assessed, it is rarely specific. An overall loss of turbinate bone may be seen with chronic destructive post-viral rhinitis, neoplasia, a focal reaction to a foreign body, or fungal rhinitis. An overlying increase in soft tissue may be seen with chronic post-viral rhinitis, neoplasia, nasonasal polyps and allergic rhinitis.
rostral nasal chambers:
TREATMENT of CHRONIC URT DISEASE
When undertaking the treatment of a cat with chronic URT disease it is helpful (where possible) to differentiate between the possible underlying causes (see diagnosis). This allows for the correct treatment to be given and a prognosis to be considered. However, since most cases of chronic URT disease result from chronic post-viral damage, it is important to remember that the likelihood for full recovery is poor.
a specific disease is diagnosed, specific treatment should be given:
• Foreign bodies can be removed. Local infection can be reduced by curettage.
• Fungal rhinitis should be treated with antifungal drugs (e.g. itraconazole, fluconazole, ketoconazole).
• Laryngeal paralysis can be ameliorated by performing a unilateral ‘laryngeal tie-back’. Any underlying cause should be corrected.
Post-viral rhinitis/idiopathic rhinitis is rarely curable. The emphasis
is on management not cure. Many of the therapeutic options discussed in
the section on treatment of cat ‘flu’ also apply here (see
Lower Respiratory Tract Disease in Cats
CAUSES OF LOWER RESPIRATORY TRACT (LRT) DISEASE (Table 1)
• Chronic bronchopulmonary disease:
This describes a commonly occurring, yet poorly understood, group of conditions that affect the airways and alveolar space. It includes ‘feline asthma’, bronchitis, broncho-pneumonia, chronic obstructive pulmonary disease, and emphysema. In many cases, the exact aetiopathogenesis of the different conditions remains unclear.
The main clinical signs are coughing, wheezing and respiratory distress. Coughing arises because of:
Disease is seen most frequently in young to middle aged cats (2-8 years of age), with female cats and the Siamese and Burmese breeds perhaps being over-represented. Historically, the cats may have previously experience cat ‘flu’, have initially shown a degree of seasonality to their disease, or had their clinical signs exacerbated by airway irritants (smoke, temperature changes, aerosols, dusty cat-litter). Coughing may conclude with a terminal retch to clear mucus from the pharynx.
In cats with episodic signs clinical examination is often unremarkable. During an episode of coughing or in cats with more protracted disease, increased lung sounds can be heard on auscultation (wheezes and crackles), the chest may take on a barrel-shape, and a ‘heave line’ may be evident.
Bacterial pneumonia is seen most frequently in immunocompromised individuals. Mixed and pure cultures of B. bronchiseptica have been found in pneumonic kittens of 5-10 weeks of age that have come from poor environments. Bacterial bronchopneumonia usually presents with a cough, tachypnoea, dyspnoea, nasal discharge, fever and depression. Auscultation may reveal increased lung sounds, crackles, wheezes, and silent areas.
Parasitic pneumonia: A. abstrusus is probably the most common lungworm of cats, although C. aerophilia infection may also occur. While A. abstrusus may be present in up to 20% of free-roaming cats, it rarely causes disease. Clinical signs are more prevalent in immunosuppressed individuals. The infection is gained by eating infected slugs or snails (the intermediate host), or infected rodents, lizards or birds (the transport hosts). Affected cats may present with a chronic cough, with associated crackles and wheezes. Perhaps the most important consideration of A. abstrusus infection is its differentiation from chronic bronchopulmonary disease, particularly ‘feline asthma’. Since both conditions can result in a eosinophil-rich bronchoalveolar lavage (see later), it is advisable to treat all coughing cats with a therapeutic course of fenbendazole (see later), prior to undertaking further investigations.
• Pulmonary oedema:
• Pulmonary contusion (trauma):
DIAGNOSIS OF LRT DISEASE
The signalment of the patient can be of help: Young cats from unhygienic multi-cat households are most likely to develop B. bronchiseptica associated bronchopneumonia, Siamese and Burmese middle-aged cats are over-represented in cats with chronic bronchopulmonary disease, and primary lung tumours are seen mainly in older cats.
From the history it is important to determine;
A cough that starts seasonally may be suggestive of ‘feline asthma’ or lungworm infection. ‘Asthmatic’ cats may cough more at night when sleeping on their owner’s bed, or at the end of a bout of play, and their clinical signs may be exacerbated by their owner’s smoking. Cats that go outside, hunt, or eat snails are more likely to become infected with Aelurostrongylus abstrusus (lungworm). A history of a road traffic accident may suggest pulmonary contusion.
Particular points to look out for include:
• The character of breathing: Generally, LRT disease is associated with expiratory dyspnoea. Severely ‘asthmatic’ cats may have a very exaggerated expiratory effort. An increased abdominal effort is seen in many dyspnoeic cats. Tachypnoea (rapid breathing), or orthopnoea (dyspnoea when recumbent), are generally associated marked respiratory compromise.
• The presence and character of a cough: A cough may be seen in LRT disease when the larger airways are affected. A dry harsh cough is found most commonly associated with tracheal or bronchial irritation, while a productive moist cough is usually associated with bronchopneumonia.
• The presence of tracheal sensitivity confirms inflammation of the upper airways.
• Assessment of the mucous membranes can help to assess the level of general peripheral perfusion, determine whether or not the animal is cyanotic (an indication of severe respiratory dysfunction), assess the patient’s level of hydration, and see whether or not the patient is septic (injected dirty-red membranes). The presence of petechial haemorrhages may suggest a clotting disorder.
• Thoracic palpation should be used to check for the presence of trauma (bruises, pain, fractured ribs), or congenital defects (‘flat-chested’ kittens, or kittens with sternal deformities). Thoracic palpation will also help to localise the position of the apex beat of the heart, and detect whether or not a cardiac thrill is present. In severely ‘asthmatic’ cats the exaggerated expiratory effort may lead to a barrel-chested appearance, and enhanced musculature (a ‘heave line’).
• Thoracic compression may be reduced in cases of air-trapping, associated with severe ‘asthmatic’ change. It may also be reduced in cases with pleural fluid accumulation or when an intrathoracic mass is present.
• Thoracic percussion can help to determine the extent of the thoracic cavity. Significant caudal extension of the pulmonary field may result from air-trapping, associated with ‘asthma’. Percussion may also help to detect fluid or soft tissue masses within the chest (a reduction in resonance, especially ventrally), or unusual gas accumulations (an increase in resonance, usually located dorsally).
• Thoracic auscultation can be used to detect the presence of wheezes and crackles, an increase or decrease in respiratory noise, to detect the extent of the respiratory field, and as part of the cardiac examination. Wheezes are generally associated with narrowing of the airways, while crackles indicate fluid within the alveoli. Respiratory noise may be increased in LRT disease, referred for the upper respiratory tract, or amplified due to the presence of air in the pleural space. To determine which is the case it is necessary to auscultate over the trachea to determine how much of the sound is referred. Percussion may help to differentiate LRT disease from a pneumothorax. A decrease in respiratory noise may be associated with fluid or soft tissue within the pleural space.
• Regurgitation may be present when disease within the thoracic cavity impedes the transit of food through the oesophagus (e.g. with thymic LSA). When regurgitation and coughing are seen together mixed disease is usually present, e.g. megaoesophagus resulting from mediastinal disease, with secondary aspiration pneumonia and coughing. Mediastinal disease alone only occasionally cause coughing. This usually results from marked enlargement of the hilar lymph nodes.
• General body condition and body weight. Severely dyspnoeic cats often have a poor appetite and so experience a degree of weight loss. Marked weight loss is more suggestive of neoplasia, or severe systemic disease, such as congestive heart failure.
• General physical examination: Many intrathoracic diseases have systemic involvement. Ocular examination may suggest the presence of uveitis or retinitis in cases of FIP, or signs of hypertension associated with hypertrophic cardiomyopathy (HCM). Detection of goiter may be helpful as hyperthyroid cats may develop HCM. Examination of the abdomen may reveal ascites in cases of FIP, congestive heart failure, or generalised neoplasia. Generalised or regional lymphadenopathy is seen most frequently in cases of neoplasia or mycobacterial infection.
Prior to undertaking further investigations, or even completing a full physical examination, it may be necessary to stabilize the patient. This can be done most simply by placing the cat in an oxygen enriched environment (oxygen box, tent, or mask).
While assessment of serum biochemistry, haematology, and FeLV/FIV status will help to gain an overall picture of the cat’s health, they rarely lead to a definitive diagnosis. For this, radiography, and the collection of samples for cytological, histopathological, and microbiological examination, are usually required.
Haematology may support a diagnosis of pneumonia (a raised neutrophil count with a left shift, and possibly the presence of toxic changes within the neutrophils). Lymphopenia may be associated with FeLV or FIV infections, or with FIP. Hypereosinophilia may be associated with ‘feline asthma’ or lungworm infection, or be unrelated to the thoracic disease (e.g. concomitant flea infestation). Serum biochemistry may on occasion be of help, and FeLV/FIV status should be assessed as an aid to determining prognosis. Any cat found to have HCM should have its serum total T4 assessed.
In theory, lungworm larvae (A. abstrusus) can be detected by faecal examination. However, it is generally more convenient to perform a therapeutic trial, using fenbendazole @ 50mg/kg/day PO for 3 days.
Where there is suggestion of cardiac dysfunction a more detailed cardiac examination should be performed. This may include ECG, thoracic radiographs, assessment of blood pressure, and echocardiography.
Ideally, the investigation should include good quality dorsoventral (DV – good for cardiac detail), ventrodorsal (VD – good for pulmonary detail), and lateral views. A general anaesthetic may be helpful as it allows control of respiration, enabling radiographs to be taken at the end of inspiration. It also allows the patient to have an increased oxygen supply.
Radiographs should be assessed for the integrity of the thoracic skeleton, presence of pleural or mediastinal fluid, masses or gas shadows, lung density and position, heart size and position, the presence of masses within the lung-fields, and the integrity of the diaphragm. Abdominal radiographs may be needed to assess the positions of the abdominal organs, the size of the liver, and the presence of ascitic fluid.
Care should be taken when assessing thoracic radiographs since on some occasions they may show no changes, despite the presence of severe disease. This is often true of chronic bronchopulmonary disease, or pulmonary thrombosis. To assess these cases further radiography may need to be repeated at a later date. Where fluid is present radiography should be repeated after thoracocentesis.
Radiography of cats with chronic bronchopulmonary disease usually reveals a prominent bronchial pattern, with or without interstitial changes, and/or patchy alveolar infiltrates. The right middle lobe may occasionally be collapsed, presumably due to occlusion of the bronchi with mucus and debris. The lungs may appear over-inflated due to air-trapping, with flattening of the diaphragm and peripheral emphysema. In very severe cases rib fractures may be evident.
Ultrasound examination can be useful at detecting masses located within the thoracic fluid. It can also be used to provide guidance for fine needle aspiration (FNA) or True-Cut needle biopsy of thoracic masses, and in the assessment of cardiac function.
Collection of samples:
• Tracheal washes can rarely be performed in conscious cats, and the technique can only sample the upper respiratory tree. The author finds this procedure unrewarding.
• Bronchio-alveolar lavage (BAL). This technique is much more rewarding. The cat is lightly anaesthetised, and placed in lateral recumbency. Where a human pediatric bronchoscope is available an endoscopically guided BAL can be collected. When performing the technique without endoscopic guidance a sterile catheter (canine urinary catheter, or an endoscopic catheter) is measured against the cat’s chest and marked at a level 2/3 of the way down the chest. The catheter is then introduced through the endotracheal tube and advanced gently until it can be advanced no further (approximately to the level at which it was pre-marked). Sterile saline is then flushed down the catheter (~5-10ml/cat). Very little of this first flush can ever be re-aspirated. A second and third flush/aspiration is then made. The cat’s chest can be coupáged (clapped) between each flush. The second flush is generally used for microbiological examination (culture), while the third flush is usually assessed cytologically. The third flush usually has the best harvest of alveolar cells. Fluid that is aspirated back should be slightly cloudy (cellular) and frothy (denotes the presence of surfactant). After performing a BAL the cat should be given oxygen enrichment for a few minutes.
Cats with bacterial bronchopneumonia usually have elevated levels of neutrophils, while chronic bronchopulmonary disease usually results in increased neutrophils, macrophages, hyperplastic epithelial cells, or excessive amounts of mucus. Cats with allergic lung disease (‘feline asthma’) may have raised numbers of eosinophils, mast cells, neutrophils and macrophages.
• Bronchial mucosal biopsy can be performed with or without endoscopic guidance. It is usually achieved using endoscopic biopsy grabs. The procedure should not be undertaken lightly as the generation of a full-thickness perforation may lead to pneumothorax or pyothorax. The collection of bronchial cells using an endoscopic brush is considerably less traumatic.
• Transthoracic FNA of a soft tissue mass can be performed with or without ultrasound guidance. When collecting FNA samples from masses in close association with the heart or major vessels, or collecting samples by True-Cut needle biopsy, ultrasound guidance is recommended. In both cases it is strongly advised that the patient be anaesthetized. The skin overlying the area of interest must be aseptically prepared.
BAL fluid should be assessed by culture and cytology:
• Culture: This requires a sterile container. All of the air should be removed from the container if anaerobic culture is to be performed. Ideally, all fluids should be assessed for both aerobic and anaerobic bacteria, fungi and yeasts. It is often beneficial to contact the laboratory that will be performing the culture prior to sending the samples. In order to detect some infections specific transport medium will be required, and the lab has to be specifically requested to look for others, e.g. B. bronchiseptica, Mycoplasma species.
• Cytology: Heparin or EDTA tubes are used for cytology. They should be processed promptly before cellular detail is lost. Where samples are to be sent away for assessment 4-6 slides should be prepared at the time of collection, and prepared as preferred the cytologist (air dried, spray fixed or fixed in alcohol). If few cells are present, the sample can be spun (200 rpm for 2-4 minutes), then smears can be made with the cell pellet. For in-house assessment, Gram stain and ‘Diff-Quik’ are suitable stains. Cell counts can be performed on EDTA anti-coagulated samples.
With LRT disease the treatment will generally depend on the specific diagnosis.
• Management of bronchopulmonary disease:
The treatment of chronic bronchopulmonary disease aims to control clinical signs rather than achieve a cure. Therapy should be tailored to each individual case.
• Alter life-style
Inhaled medication (approximate prices as of January 2004):
Suggested treatment regimens:
Moderate cases: i.e. clinical signs are occurring on a daily basis.
Severe cases: Treat as for moderate cases (i.e. Salbutamol [1-2 doses, 2-4 times daily] + inhaled steroids [1-2 doses, twice daily]). However, since inhaled steroids may take 1-2 weeks to achieve maximal effect oral steroids are also required. These can usually be reduced or discontinued once the disease is under better control, typically over 2-4 weeks. (i.e. 5mg prednisolone twice daily for 1 week, then 5mg prednisolone once daily for 1 week, then 5mg prednisolone every other day for 1 week, then stop).
Salmeterol (‘Serevent’), is a long-term bronchodilator that takes up to 1-2 hours to take effect but lasts ~8-12 hours. (See above for treatment regimens). Use of high doses can result in tachycardia and muscle twitching.
Terbutaline (‘Bricanyl’) 0.625-1.25 mg PO q12h
• Theophylline: Slow release theophylline (‘Corvental-D’) 20-25mg/kg PO q24h.
Fluticasone propionate (‘Flixitide’), Beclomethasone bipropionate (‘Becotide’,‘Qvar’) and Budesonide (‘Pulmicort’) are available as inhaled medications. They have virtually no systemic effects (especially Fluticasone and Budesonide). In cats they can occasionally cause airway irritation. (See above for treatment regimens).
Prednisolone 0.25-2 mg/kg PO q12h, then taper off slowly.
• Anti-serotonergics: Cyproheptadine (‘Periactin’) 0.1-1.0mg/kg PO q8-24h
• Leukotriene receptor antagonists: Zafirlukast (‘Accolate’) 5-10mg/cat PO q12 h.
• Antibiotics: Cats with chronic bronchopulmonary disease are very susceptible to opportunistic airway infections. Whenever infection is found it should be treated. Ideally, selection of antibiotics should be made on culture and sensitivity. However, empirical choices include doxycycline, penicillins, and fluoroquinolones. Treatment for 4-6 weeks is often required. Recommended treatment for mycoplasmosis is doxycycline 5mg/kg PO q12h.
• Mucolytics: Bromhexine (‘Bisolvon’) 3mg/cat IM/day, or 1mg/kg PO/day.
In severe respiratory distress;
Some drugs can be administered via an inhaler or in nebulised air. Unfortunately, administration via nebulised air can result in their therapeutic concentrations taking a longer time to be reached. e.g. Salbutamol (two doses every 30 minutes for up to 2-4 hours) and/or Fluticasone (see above).
2. Bacterial bronchopneumonia:
3. Lungworm infection:
Figure 1. Causes of lower respiratory tract disease in cats
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