Flashcards in Respiratory tract diseases of SA 2 - approach to dyspnoea and common conditions of the dog and cat Deck (46):
What are the 4 main categories of dyspnoea causes?
Loss of thoracic capacity
Pulmonary parenchymal disease
Others - metabolic, physiological, vascular
What must happen to cause obstructive disease?
• Significant obstruction of the URT
obstruction of a large number of the small airways of the LRT
What do URT obstructions sound like?
increased inspiratory noise (as URT tends to narrow on inspiration)
What do LRT obstructions sound like?
increased expiratory effect
List some causes of airway obstruction - 12
- Nasal obstruction
- Laryngeal paralysis
- Tracheal collapse
- Brachycephalic obstructive airway disease (Soft palate, Stenotic nares, Laryngeal collapse)
- Extralumenal mass lesions
Brachycephalic obstructive airway disease
Broad causes - loss of thoracic cavity - 4
• Compromise due to Fluid/air in pleural space
• Organs displaced from abdomen
• Less commonly
– Marked cardiomegaly
DDx - loss of thoracic cavity - 7
– Pleural effusion
– Ruptured diaphragm
– Cranial abdominal organ enlargement
– Gross cardiomegaly
– PPDH (pericardio-peritoneodiaphragmatic hernia)
List broad causes of pulmonary parenchymal disease - 3
- Diffusion abnormalities due to disease of the alveolar wall and interstitium
• Alveolar flooding with oedema, blood or exudate
• Abnormal pulmonary vascular supply
– Ventilation-perfusion mismatch
Ddx - pulmonary parenchymal disease - 6
- Pulmonary oedema - Cardiogenic or non-cardiogenic
- Neoplasia; primary or secondary
- Pulmonary haemorrhage
- Pulmonary fibrosis; idiopathic or toxic
- LRT parasites (Aelurostrongylus or Filaroides hirthii)
DDx - miscellaneous/ metabolic/ physiological causes of dyspnoea - 9
[MAY NOT BE ASSOCIATED WITH OBVIOUS ABNORMALITIES OF THE RESPIRATORY TRACT]
• CNS disease
• Endocrine disease
• Neuromuscular disease
• Thoracic wall abnormalities
2 broad causes of pulmonary vascular disease as a cause of dyspnoea
- Pulmonary hypertension (causes increased RV afterload)
- pulmonary thromboembolic disease
What is the basic approach to a dyspnoiec patient?
- Same as other systems - history, PE, DDx, diagnostics
- BUT marked dyspnoeic cases may require emergency stabilisation first. Minimise stress (esp. cats). Oxygen supplementation will improve the dyspnoea.
What is the most effective technique to confirm pulmonary parenchymal or pleural disease?
Thoracic radiographs (n.b. URT obstruction, metabolic, physiological and vascular causes often have normal radiographs).
What should you do with your initial assessment of dyspnoeic patients?
Try to differentiate between types of dyspnoea
• OBSTRUCTIVE - URT obstruction and dyspnoea
associated with noise and increased inspiratory effort
– Laryngeal paralysis
– Tracheal collapse - honking sounds
• PLEURAL (i.e. loss of thoracic cavity)- decreased respiratory noise on auscultation, fluid line on percussion
• PULMONARY – may have increased respiratory noise on auscultation particularly wheezes and crackles
How common is pulmonary parenchymal disease in dogs/cats?
Significant cause but probably overall less common than airway disease and pleural effusion.
List examples of pulmonary parenchymal disease in the dog/cat - 9
- Pulmonary oedema - cardiogenic or non-cardiogenic
- Pulmonary haemorrhage
- Pulmonary neoplasia
- Pulmonary fibrosis
- Pulmonary infiltrate with eosinophils
- Parasitic pneumonia
- FAAD (feline asthma)
- Paraquat poisoning
What emergency measures are needed for URT obstruction? 3
- establish airway
- anaesthesia and intubation to bypass obstruction
- tracheostomy (severe cases, bypass upper airway completely)
What emergency measures are needed for pleural effusion/pneumothorax?
How can radiography help you determine cause for dyspnoea?
• Pulmonary disease
• Pleural disease
• Absence of pleural and/or pulmonary disease implies
the presence of obstructive or non-respiratory cause
for the signs.
T/F: causes of URT obstruction tend to be surgical diseases
How to investigate pulmonary parenchymal disease? 3
THORACIC RADIOGRAPHS - best method to confirm involvement of parenchyma, look for lung patterns
HAEM/BIOCHEM - look for evidence of inflammatory disease and discriminate eosinophilic from neutrophilic inflammation. Some causes of parenchymal disease may give normal readings with these tests.
TRACHEOBRONCHIAL or BRONCHOALVEOLAR WASHES - most useful for determining the type of inflammation in the LRT, may also enable ID of the primary agent that is involved.
When would you see eosinophilic inflammation with pulmonary parenchymal disease? 3
- pulmonary infiltrate with eosinophils (PIE)
When might you see neutrophilic inflammation with pulmonary parenchymal disease?
What is another name for cat flu?
Feline infectious upper respiratory disease complex (most likely to occur in groups of cats, widespread vaccination has reduced the incidence but outbreaks still common).
What organisms are implicated in cat flu? (majorly *, minorly -) 7
* FHV-1 (also referred to as FVR)
* Feline calicivirus
* Chlamydophila felis
* Bordatella bronchiseptica (questioned)
- Feline Reovirus
- Cowpox virus
Clinical signs - cat flu
- variable (organism, level of exposure, immune status)
- FVR - more severe
- similar CS
- Chlamydophila --> ocular signs
- Calicivirus --> oral ulceration and in rare cases lameness and sometimes severe and fatal systemic disease.
Conjunctivitis, rhinitis, tracheitis, laryngitis
Sneezing, hypersalivation, serous or mucopurulent
Dendritic corneal ulcers
• Congenitally infected kittens
– Encephalitis and hepatitis
Outline feline calicivirus
Rhinitis, conjunctivitis, interstitial pneumonia
What about pathogenic strains of calicivirus
Relatively new syndrome described in US, UK and
elsewhere associated with calicivirus
• FCV-associated virulent systemic disease
• Respiratory disease
• Cutaneous oedema, ulcerative dermatitis
• Anorexia, jaundice
• up to 50% mortality
When is a definitive diagnosis required?
only in cases of an outbreak as specific control measures need to be instituted.
viral isolation (FCV, FHV)
PCR (FHV, FCV and Chlamydophila)
Why is serology not useful for diagnosis?
widespread vaccination - most cats will have positive Ab titres to the causal organisms.
Advisory Board for Cat Diseases
Treatment - feline infectious respiratory disease
Most important = supportive care. Most nursing should be done at home (because contagious). Don't share airspace with healthy cats. Thorough disinfection and washing. Good hygiene.
What are specific treatments that are indicated for C.felis or B.bronchiseptica infection?
Oxytetracycline or Doxycycline (but these should be avoided in young animals and pregnant queens due to the risk of enamel staining on developing teeth)
What concurrent infections should you check for and when?
In a particularly debilitated patient or in a group of
animals affected by an outbreak it may be worth
checking status with relation to FIV and FelV.
T/F: FHV and FCV can both be chronically shed by animals that have been previously infected
True. Shedding may occur continuously (more likely with Calicivirus) or intermittently at times of stress (more likely with Herpesvirus)
What are the 3 main routes of exposure of cats to FHV and FCV?
1.) close contact or aerosol (<2m)
2.) environmental contamination (fomites. FHV can persist for up to 24 hours and FCV for up to one week)
3.) Persistent carriers (shedding the virus without CS)
How can herpes and calicivirus be controlled? 3
Routine vaccines - either LAV (systemic), live IN or inactivated vaccines.
What are the problems with calicivirus vaccines?
Calicivirus - not all strains are covered by the vaccine so CS may develop in vaccinated animals.
Cats may also develop infection with agents against which they are not vaccination (Chlamydia and Bordatella).
T/F: there are some vaccines available agianst Chlamydia and Bordatella
True - but not widely used.
Suggest tx options for viruses - 3
Agents suggested to be of benefit but with limited proof
• IFN – Not licensed for use in cats with cat flu (licensed for use in Felv/FIV) – May have some effect
• Aciclovir – Limited efficacy in cats with FHV ulceration
What are general tx principles for feline respiratory problems? 4
• Assist respiration – Clear secretions from external nares – Decongestants? – Nebulise saline to moisten airways and humidify atmosphere
• Adequate hydration - fluid therapy if necessary
• Provide nutritional support
• Antibiotics to control secondary infections/treat
[Ideally patients treated at home unless severely ill]
What are general problems with vaccines? 2
1.) Vaccine induced disease - Inappropriate route of administration or inherent pathogenicity
2.) “Vaccine breakdowns”- Diversity of aetiological agents means that vaccinated cats can still develop signs of flu. Heterogeneity of FCV strains mean vaccine does not necessarily protect against all FCV. Animal incubating disease at time of vaccination will still show CS.