resp notes cat diseases

Question 1

Feline herpesvirus
- character of infection
- histo lesions

Answer 1

• latent after the initial infection is cleared by the immune response
• recrudescence may occur during stressful periods, causing disease and/or infecting other cats
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• Intranuclear inclusion bodies are often present in diseased tissues

Question 2

Feline calicivirus
- nature of infection, shedding
- rare forms?

Answer 2

• infections may be chronic, and infected cats shed the virus almost continuously
• rare but highly virulent strains of feline calicivirus cause severe systemic and fatal disease

Question 3

feline herpes and calicivirus
- tissues they infect
- damage
- signs
- possible sequelae

Answer 3

• mainly infect the upper respiratory tract and conjunctival epithelium
• necrosis of epithelial cells
• can infect lungs and cause primary viral pneumonia in some cases (kittens)
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• young and old cats
• mucopurulent nasal and ocular discharge and sneezing
• +/- fever
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• may be secondary bacterial bronchopneumonia, or chronic rhinitis and sinusitis

Question 4

Why can upper respiratory infections become chronic?

Answer 4

• Persistent infections. Latent herpesvirus infection may be reactivated in times of stress. Calicivirus and Bordetella infections are often persistent.
• Respiratory defences are impaired. FeLV or FIV infections impair nasal defences. Chronic rhinitis destroys ciliated epithelium and excavates turbinate bone, impairing clearance of mucus from the nasal cavity.
• Infections of sinuses (sinusitis) and of bony tissue (osteomyelitis) may be difficult to eliminate.

Question 5

Auditory (nasopharyngeal) polyp
- who gets it?
- where does it arise?
- where can it go, and effects

Answer 5

• young adult cats
• arises in the middle ear or auditory (Eustachian) tube
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• may grow into:
• pharynx to cause gagging or dysphagia,
• nasal cavity to cause stertor and nasal discharge
• middle ear to cause head tilt, head shaking, or Horner’s syndrome

Question 6

The major nasal neoplasms of cats are?

Answer 6

• primary nasal lymphoma and adenocarcinoma
• also, squamous cell carcinoma and other tumours of the nasal planum
• Sinonasal lymphoma typically begins in the nasal cavity (rather than arising elsewhere and spreading to nasal tissues)

Question 7

Cryptococcus neoformans
- what is it? found where?
- histology
- how it infects cats
- possible diseases?

Answer 7

• fungus that is maintained in avian feces
• thick capsule that invokes very little inflammation > gross lesions appear as a gooey gelatinous mass of yeast bodies
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• inhalation leads to nasal disease
• can invade from the nasal cavity through the cribriform plate to cause meningoencephalitis
• Aspiration of infected nasal mucus may cause pneumonia
• immunosuppressed individuals
  > hematogenous spread results in ulcerating cutaneous nodules, uveitis, or lesions in the viscera

Question 8

chronic bronchitis and asthma in cats
- how this arises
- signs
- histology?
- obstruction causes?

Answer 8

• most likely a chronic hypersensitivity response
• cough, wheeze, or dyspnea, as a result of increased airway resistance due to bronchoconstriction
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• eosinophilic inflammation affects the bronchi and/or bronchioles
• goblet cell hyperplasia
• increased mucus secretion
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• Airway obstruction is the result of:
• bronchoconstriction
• obstruction by mucus and inflammatory cells
• edema of the airway wall

Question 9

bacterial bronchopneumonia in cats
- etiology, pathogens

Answer 9

• often secondary to upper respiratory infections
• The major causes include:
• Pasteurella multocida
• Bordetella bronchiseptica

Question 10

pulmonary neoplasia in cats
- what is common? appearance / distribution?
- metastases?
- neoplasms that metastasize to lung?

Answer 10

• Pulmonary adenocarcinoma is fairly common
• focal lung mass > but frequently develops innumerable tiny metastases throughout the lung, or disseminates within the pleural cavity
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• Distant metastasis is frequent: footpad, skeletal muscle, bone, eye, brain, or skin
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• Common neoplasms that metastasize to the lung of cats include:
• lymphosarcoma
• mammary carcinoma
• oral squamous cell carcinoma

Question 11

Toxoplasma gondii
- what is it?
- general life cycle
- who is susceptible
- infection route
- replication, lesions
- type of lung disease?

Answer 11

• apicomplexan protozoan
• Cats are the definitive host (they pass oocysts in feces)
• Disease occurs in cats, sheep, dogs, humans, and others
• Infection is by ingestion of oocysts containing sporozoites (from contamination with cat feces), by ingestion of tissues of an intermediate host which contain bradyzoites, or by congenital infection
• Asexual replication within host cells results in either release of tachyzoites by rupture of the cell (resulting in necrosis of tissue and
  infection of adjacent cells), or formation of cysts containing bradyzoites that are infectious if ingested.
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• mostly immunosuppressed
• Clinical signs are highly variable; may include respiratory, nervous, hepatic, pancreatic, cardiac, ocular, muscular, and/or enteric disease.
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• diffuse interstitial pneumonia

Question 12

aelurostrongylus abstrusus
- what is this
- who gets this?
- IH?
- signs? issues?
- lesions

Answer 12

• Infection with this nematode is common in young cats with access to the snail or slug intermediate hosts
• often no clinical signs
• common cause of anesthetic death when spaying/neutering humane society cats
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• soft 2-5 mm diameter nodules beneath the pleura of the dorsal lung
• worms are too tiny to be seen grossly
• each nodule contains microscopic adults, larvae and eggs, and a granulomatous inflammatory response

Question 13

paragonimus kellicotti
- what is it?
- route of infection?
- lesions?
- illness? significance?

Answer 13

• trematode (fluke) parasite
• acquired from crayfish intermediate host or from a paratenic host
• adult flukes and their pigmented eggs reside in cyst-like cavitations in the lung
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• most infected cats have no clinical signs
• However, the
  infection can be significant in two ways:
• The cyst can be mistaken radiographically for a neoplasm, leading to unnecessary euthanasia.
• Rupture of the cysts causes pneumothorax with acute dyspnea.

Question 14

Feline infectious peritonitis
- can it affect lungs? how?
- lesions?

Answer 14

• some cats with FIP have pleuritis with or without lesions in other tissues
  > tiny raised white granulomas are present on the pleural surface of the lung
  > In the wet form, cloudy, protein-rich fluid fills the pleural cavity

Question 15

pyothorax in cats
- causes, pathogens?
- appearance?

Answer 15

• penetrating injuries contaminate the pleural cavity with bacteria such as Pasteurella multocida
  > suppurative inflammatory response fills the pleural cavity with cloudy fluid

Question 16

chylothorax in cats
- nature of fluid?
- causes?

Answer 16

• accumulation of lymph fluid in the chest
  > characteristically high lymphocyte count and high triglyceride concentration compared to serum
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  The causes include:
• Heart failure, because increased central venous pressure reduces drainage from thoracic duct into vena cava. Hypertrophic cardiomyopathy is the most common heart disease causing chylothorax.
• Mediastinal masses (thymic lymphoma, thymoma).
• Thrombosis of the vena cava.
• Many cases are idiopathic.

Question 17

hydrothorax in cats
- appearance, cause?

Answer 17

Hydrothorax appears as clear, low-protein fluid in the chest, and is most commonly the result of right- or left-sided heart failure