Respiratory tract therapeutics

Question 1

Goal of oxygen therapy is to

Answer 1

increase the fraction of inspired oxygen FiO2.

▪ Improves oxygen delivery, decreases the risk of organ damage due to hypoxia.

Any animal with respiratory difficulty, any animal in shock should get oxygen.
▪ Especially when PaO2 < 70 mmHg, SpO2 < 93%.

Methods of O2 administration:
▪ Face mask, flow-by, oxygen collar, oxygen cage, nasal oxygen catheter, mechanical ventilation.

NB Oxygen is no wonder drug, it can be toxic!

Question 2

Describe flow-by oxygen therapy.

Answer 2

▪ Keep the oxygen tube as close as you can

▪ Easy, well tolerated, for short term emergencies

▪ An Oxygen flow rate of 2-3l/min gets you 25-40% FiO2.

Question 3

Describe face mask oxygen therapy.

Answer 3

▪ Place a mask over the muzzle

▪ Easy, higher FiO2 than in flow-by (>40%).

▪ Do not place a mask that is too small and tight!

Question 4

Describe oxygen collar O2 therapy.

Answer 4

▪ Easily made

▪One size bigger collar, wrap 75% of the opening, tape oxygen tube ventrally.

▪Not for panting dogs, risk of hyperthermia

▪ Flow rate approximately 1l/10kg/min

Question 5

Describe nasal oxygen catheter O2 therapy.

Answer 5

▪ For long-term use in hospital setting.

▪ Catheters simple to place,
minimal equipment, well tolerated.

▪ Needs Humidified oxygen source!

▪ Flow rate maximum 1l/10kg/min

Question 6

Describe oxygen cage O2 therapy.

Answer 6

▪ Long-term use in hospital setting, expensive.

▪ Pro is Administration of a known FiO2

Question 7

Describe corticosteroids in resp. patients.

Answer 7

▪Reduce inflammation by inhibiting the production of inflammatory mediators and decreasing the migration of inflammatory cells to the airways.

▪Injectable, oral, inhaled steroids avail.

▪ Short-acting oral steroids preferred over long-acting steroids.

▪ Prednisolone preferred over injectable methylprednisolone acetate.

▪Dose and treatment length depend on the individual, severity of the disease, response to treatment, side effects.

Question 8

Indications for use of Injectable corticosteroids. (2)

Give two drug examples, doses if you remember them.

Answer 8

▪ Emergency treatment for upper airway
obstruction

▪ Emergency treatment for feline asthma/bronchitis

▪ Dexamethasone 0.1-1 mg/kg iv, long-acting

▪ Hydrocortisone 5-10 mg/kg iv, rapid-acting

Question 9

Indications for use of oral corticosteroids in cats vs dogs. (1+4)

Give two drug examples, doses if you remember them.

Answer 9

Long-term management of inflammatory airway diseases:
▪ Cats: Feline asthma/bronchitis

▪ Dogs: Chronic bronchitis,
eosinophilic bronchopneumopathy,
idiopathic pulmonary fibrosis?,
tracheal collapse

Prednisolone po is preferred over prednisone.

▪ Feline asthma: 1-2mg/kg BID for 1-2 weeks, then gradually taper down.

▪ Canine chronic bronchitis: 0,5-1mg/kg BID 1 week or until signs resolve, then gradually taper.

▪ Canine eosinophilic bronchopneumopathy: 1mg/kg BID for 2 weeks, then gradually taper down.

Question 10

Indications for use of inhaled corticosteroids in cats vs dogs. (1+2)

Give two drug examples, doses if you remember them.

Answer 10

Long-term management of inflammatory airway diseases:
▪ Cats: Feline asthma/bronchitis

▪ Dogs: Chronic bronchitis,
eosinophilic bronchopneumopathy

▪Minimal systemic adverse effects compared to oral medications.

▪ Fluticasone or budesonide metered dose inhaler, fitting facemask and chamber!

Question 11

Give two drug examples of inhaled corticosteroids commonly used in small animals.

Answer 11

Fluticasone & budesonide (metered dose inhalers)

Question 12

Describe Aerokat® and Aerodawg®

Answer 12

Brand of small animal corticosteroid Inhalation chamber and facemask.

▪May take several days up to two weeks
before full effect.

▪Use oral corticosteroids to start treatment
if immediate treatment needed.

Question 13

Describe Inhaled fluticasone.

Answer 13

▪ 50µg, 125µg or 250µg/puff concentrations available

▪Dose depends on the severity of the disease and the size of the animal.

Cats: 50-125µg/puff, 1 puff BID starting dose.

Dogs: 125µg/puff, 1 puff BID < 10kg starting dose

and

250 µg/puff, 1 puff BID > 10kg starting dose

Question 14

Antibiotics and the dyspneic or respiratory patient.

Answer 14

▪Not all coughing animals require antibiotic treatment

▪ Viral infections common!

▪Ideally, antibiotic choice should base on bacterial culture of a respiratory sample and antibiotic sensitivity testing which is Often not possible!

▪ Know what are the most common bacteria are, make an empirical choice, consider your patient characteristics.

Question 15

Bacterial pneumonia typically presents with the following:

Answer 15

▪ Animal systemically ill, respiratory distress, elevated CRP (dogs), +/- fever,
+/- leukocytosis, left shift, neutrophilia, leukopenia

▪ Alveolar pattern in thoracic radiographs (typical in dogs)

Question 16

Bacterial tracheobronchitis typically presents with…

Answer 16

▪ Persistent cough, more common in young dogs, otherwise bright and alert

Question 17

Pyothorax is a

Answer 17

▪ Bacterial infection of pleural cavity with free, highly cellular, bad-smelling fluid in pleural cavity (Intracellular bacteria).

Question 18

Common pathogens and Antibiotic choice for dogs with bacterial pneumonia.

Answer 18

▪ Pasteurella, Klebsiella, E. coli, Streptococcus, Staphylococcus,
Bordetella bronchiseptica

Mild disease: Doxycycline po / trimetoprim sulfonamide po / amoxicillin-clavulanate po

Severe disease: Ampicillin + enrofloxacin iv / amoxicillin-clavulanate iv

Question 19

Antibiotic choice for Bacterial tracheobronchitis (Bordetella bronchiseptica!) in dogs. (3)

Answer 19

▪ Doxycycline po / trimetoprim sulfonamide po / amoxicillin-clavulanate po

Question 20

Cats with Respiratory infections caused by Mycoplasma, Pasteurella, Bordetella, Streptococcus spp., Stapyhylococcus spp., Escherischia coli.

Whats your antibiotic choice?

Answer 20

Mild disease: Doxycycline po / amoxicillin-clavulanate +/- fluoroquinolone po

Severe disease: Ampicillin + enrofloxacin iv

Question 21

Dogs with Pyothorax. What pathogens may be at play?
Whats your AB choice?

Answer 21

Broad spectrum, both aerobe and anaerobe coverage

▪ Pasteurella spp. Actinomyces spp., E. coli, Nocardia spp. Streptococcus spp., Staphylococcus spp., Corynebacterium, Bacteroides, Fusobacterium

Choose Ampicillin or clindamycin + enrofloxacin iv.

Question 22

Cats with Pyothorax. What pathogens? Whats your AB choice?

Answer 22

Broad spectrum, both aerobe and anaerobe coverage.

▪ Pasteurella spp. Clostridium spp., Fusobacterium spp, Bacteroides spp., Actinomyces spp., Peptostreptococcus spp., Mycoplasma spp. …

Choose Ampicillin or amoxicillin-clavulanate.

Question 23

When are bronchodilators needed?

Answer 23

Emergency treatment for asthmatic attack in cats.

+ Long term management of Cats with asthma/bronchitis which continue to have symptoms despite corticosteroid treatment.

May be tried in dogs with airway disease. but NB! In dogs, Reversible smooth muscle contraction leading to bronchoconstriction is not a feature in dogs with airway disease.

Question 24

Name 2 groups of bronchodilators.

Answer 24

Methylxanthines and ß-2 agonists.

Question 25

Name and Describe a methylxanthine + dosages.

Answer 25

Theophylline po

▪ Relatively weak bronchodilator, not for emergency use

Additional benefits:
▪ Increases diaphragmatic strength, reduces respiratory effort, stimulates mucociliary clearance (dogs).

Dosages:
▪ Extended release 10mg/kg BID dogs, 100mg/cat SID or eod (?)

Low therapeutic index
Consider drug interactions!

▪ NB Reduce dosage or discontinue when on enrofloxacin

Question 26

Name and Describe a beta-2 agonist bronchodilator + dosages.

Answer 26

Parenteral terbutaline
▪ Fast and short-acting

▪ Emergency treatment for asthmatic attack in cats 0.01mg/kg iv, im, sc, can be repeated once after 30 min if no effect

Question 27

Name 2 inhaled options for corticosteroids.

Answer 27

ß-2 agonists:
▪Salbutamol inhalation (also called albuterol) or Combined salmeterol/fluticasone –inhalation

Question 28

Describe Salbutamol inhalation (also called albuterol).

Answer 28

▪ Fast-acting
▪ Proinflammatory in cats! Only use for rescue!

▪ Cats: One 100 µg puff when asthmatic attack, can be repeated in 30 min

▪Dogs: 1-2 puffs of 100 µg BID-TID

Question 29

Describe Combined salmeterol/fluticasone –inhalation

Answer 29

▪ Longer acting

▪ Cats: E.g. 25µg/125µg 1 puff BID

▪Dogs: as in cats if < 10 kg, 2 puffs BID if > 10 kg

Question 30

Describe Cough suppressants in small animals.

Answer 30

Palliative treatment when cough is disturbing sleep or exhausting the dog

▪ Centrally acting antitussives inhibit cough reflex

▪ Do not use if cough is productive

▪Maropitant suppresses cough in dogs

1. detromethorphan
2. butorphanol
3. hydrocodone

Question 31

Describe mucolytics in small animals.

Answer 31

Makes secretions more watery and easier
to cough/sneeze out.

▪ Saline drops to nostrils in rhinitis

▪ Saline nebulization with a nebulizer

▪ Nebulizer turns liquid into mist

▪ N-acetylcysteine?

Question 32

Sedation of respiratory patients.

Answer 32

▪Light sedation useful in dyspneic patients:
stress increases oxygen demand!

▪ Consider short-acting drugs with minimal respiratory effect

Butorphanol
▪ Light sedative and cough suppressant
▪ Dogs: 0.1-0.4mg/kg iv, 0.25-0.5mg/kg sc, im
▪ Cats: 0.10-0.25mg/kg iv, 0.2-0.4 mg/kg im

Acepromazine may be used in dogs if otherwise healthy.

Do not use medetomidine or dexmedetomidine!