Infectious Diseases - Cats Flashcards
What is the definition of ‘infectious’?
Ability of a disease to be passed from one person/animal/plant to another
What is a zoonosis?
A disease that can be passed from animals to humans
Whats is a reverse zoonosis?
A disease than can be passed from humans to animals
What is a community-acquired infection?
A disease that is acquired in the community
What is a nosocomial infection?
A disease that is acquired in hospital
What is a pathogen?
A disease-causing organism
What is a commensal?
An organism that inhabits a specific mucosal surface in the body and is a normal finding
What are bacteria?
Single celled, prokaryotic organisms
How do bacteria reproduce?
Binary fission
What are the main morphologies of bacteria?
Coccoid
Bacillus
Spiral
How can a bacterial infection be diagnosed?
Organism detection (microscopy and/or culture) Demonstration of antibody
What is the treatment for bacteria?
Antibiotics
What is a virus?
Sub-microscopic organism of diverse morphology
How does a virus replicate?
Requires a living host cell
How can a viral infection be diagnosed?
Demonstration of virus via antigen or DNA
Demonstration of antibody presence
What are the treatments for viruses?
Antivirals when available
Supportive therapies
What are fungi?
Multi-cellular eukaryotic organisms
How do fungi reproduce?
Capable of sexual and asexual reproduction
How can fungal infections be diagnosed?
Organism identification (microscopy, fungal culture, antigen, DNA) Demonstration of antibody
How are fungal infections treated?
Antifungals - prolonged treatment often required
How do parasites reproduce?
Capable of sexual and asexual reproduction
What are parasites?
Eukaryotic, multi-cellular organisms
How are parasitic infections diagnosed?
Usually via identification of organism/microscopy/gross visualisation, also antigen/DNA
How are parasitic infections treated?
Anti-parasitics - specific to type of parasite
What are protozoa?
A type of eukaryotic parasite which commonly cause GI or multi-systemic disease
What are the 2 forms of protozoa?
Cyst (dormant) and trophozoite (active)
How are protozoal infections diagnosed?
Organism detection - microscopy/antigen/DNA
Demonstration of antibody
How are protozoal infections treated?
Anti-protozoals
Some respond to antibiotics
Through which routes can veterinary diseases often be spread?
Human hygiene issues Fomites Exoparasites Fighting between animals Aerosols Blood product sharing Vomiting/diarrhoea
What are the 4 most common causes of feline upper respiratory tract disease (cat ‘flu’)?
Feline herpesvirus
Feline calicivirus
Chlamydia felis
Bordetella bronchiseptica
What is the structure of feline herpesvirus-1?
Enveloped DNA virus
How is feline herpesvirus-1 contracted?
Fomites
Close contact transmission (ocular/saliva/nasal)
Immunosuppressive drugs increase susceptibility
How does feline herpes develop once contracted?
Stressful event makes latent infection more likely to become active
Reactivation of shedding 4-12 days later, shed for 1 week
(May or may not have clinical signs)
What is the general structure of feline calicivirus?
Non-enveloped, RNA virus
Do cats become carriers after exposure to calicivirus?
Yes - post-infection FCV persists in oropharyngeal tissues for >1 month
Lifelong in some cats
How is feline calicivirus transmitted?
Close contact (saliva/nasal/ocular)
Aerosols
Fomites
Shed in urine/faeces of infected cats
What is the incubation period of FHV/FCV?
2-6 days, viral shedding starts 1 day post-infection (before clinical signs)
What are the clinical signs of feline herpesvirus?
Dendritic ulcers of the eye
Gingivostomatitis (tongue lesions)
Nasal and ocular discharge
Conjunctivitis
What are the clinical signs of FCV?
Nasal and ocular discharge
Conjunctivitis
Gingivostomatitis
Lingual ulcers
How is FCV/FHV-1 diagnosed?
Conjuctival/pharyngeal swabs
PCR testing
Virus isolation (FCV)
Culture to check for Chlamydia felis/Bordetella
What general nursing considerations should be taken when nursing cat ‘flu?
Clean face with warm, wet, soft wipes
Barrier creams to prevent scald from discharge
Ocular lubricant
Nebulisation to loosen secretions
Injectable medications when possible, no oral handling
Restrain without hand under mouth
What nutritional considerations should be taken when nursing a FCV/FHV cat?
Correct dehydration/electrolyte imbalances fist (within 48hr)
Oral preferable - small volume of palatable, warm food
Offer fresh food frequently
Gentle hand feeding if at home with owner
Consider anti-emetics or appetite stimulants
Severe cases may need tube feeding
What specific therapies are available for treating FCV?
Recombinant feline interferon - improves mouth inflammation
What specific therapies are available for treating FHV?
Famciclovir (antii-virals)
Lysine (oral) improves conjunctivitis (only benefits in home)
When would you suspect a secondary bacterial infection with FCV/FHV?
Suspect if thick, mucopurulent discharges - ideally culture and sensitivity
How do you treat a secondary bacterial infection to FHV/FCV?
Doxycycline first line choice
(Oesophageal stricture risk - amoxycillin clavulanate is an alternative)
Opioids/NSAIDs
Mucolytics
What patient handling/hygiene considerations should be made when nursing a cat with suspected/diagnosed FCV/FHV?
Isolation facilities if possible
Barrier nursing (disposable equipment) - single staff member
Hand-washing very important - also wash arms
Leave cage empty for 2 days after end of stay
Is there a vaccine available for FCV/FHV?
Yes - part of core vaccines for kittens
From 6-8 weeks old, every 3-4 weeks until at least 16 weeks old
What form is the vaccine for FCV/FHV?
Attenuated live vaccine
Inactivated form available only for use in immunosuppressed/pregnant cats
How can you manage prevention/outbreaks of FHV/FCV?
Minimise stress and overcrowding
House cats individually in catteries
Quarantine new additions to multi-cat households for 3-4 weeks/swab newcomers
Do not breed from clinically affected queens
What are the signs of HIGHLY VIRULENT calicivirus?
severe cutaneous and respiratory signs
Marked pyrexia, anorexia, lethargy and weight loss
+/- death, may be peracute
What is Chlamydia felis?
What form does it take?
Obligate intracellular bacteria
Exists in 2 forms - reticulate body (non-infectious) and elementary body (infectious)
How is chlamydia felis transmitted?
Direct contact (usually ocular discharge)
Fomites
Aerosols
How long is the incubation period for Chlamydia felis?
2-5 days
What is the main clinical presentation of chlamydia felis?
Conjunctivitis (acute and chronic/recurrent)
+/- upper respiratory signs
Sometimes corneal ulceration (rare)
Which cats are more susceptible to chlamydia felis?
Young cats (2-12 months) living in a multi-cat household
How is C. felis diagnosed?
PCR (conjunctival swabs)
What is the treatment for a C. felis infection?
Is there a vaccine?
Oral doxycycline, 4 weeks Vaccine available (non-core)
What is Bordetella bronchiseptica?
An aerobic, gram negative, cocco-bacilli bacteria
In which dogs is B. bronchiseptica found?
Found in some clinically healthy dogs as well as those with respiratory disease
Prevalent in high density populations (boarding kennels, shelters) - highly contagious
How is B. bronchiseptica transmitted?
Airborne
Fomites
Infected water sources
What is the incubation period for B. bronchiseptica?
2-10 days
What are the main clinical presentations of B. bronchiseptica?
URT/large airway disease - sneezing, mucopurulent nasal discharge, harsh cough
How is B. bronchiseptica diagnosed?
Bronchoalveolar lavage (lung swab) - culture and sensitivity, PCR
What is the treatment for B. bronchiseptica?
Doxycycline 1-4 weeks
Is there a vaccine available for B. bronchiseptica?
Intra-nasal vaccine available (non-core)
What are the 2 most common retroviruses in cats?
Feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV)
What are the major genes in retroviruses?
gag - encodes core viral proteins
pol - encodes enzymes
env - encodes envelope glycoproteins
Is FeLV more or less pathogenic than FIV?
More pathogenic (more direct association with clinical disease)
What other conditions can be caused by FeLV?
Bone marrow disorders
Haematopoietic neoplasia
Immunosuppression
How is FIV transmitted?
“fighting” virus
Bite wounds - high concentrations in saliva
Vertically from mother (1/3 of kittens)
Infected blood products
How is FeLV transmitted?
Allogrooming and fomites (prolonged oronasal salivary exposure)
Vertically from mother
Infected blood products
Which cats are more likely to contract FIV?
Fighting cats with outdoor access, older and male, ferals
Which cats are more likely to contract FeLV?
Close-contact cats
Outdoor access
Entire cats
3 years (median age)
What is involved in the acute phase of FIV?
Virus is contracted and replicates in local lymphoid tissue
Peak viraemia 8-12 weeks post-infection, causes transient illness (lethargy, pyrexia, inappetence, GI signs, weight loss)
What is involved n the asymptomatic phase of FIV?
Disease present but may last for life without causing further clinical problems
Impaired lymphocyte response to infectious agents (virus destroys CD4+ cells)
What happens if FIV progresses to the terminal phase?
Acquisition of opportunistic infections
Chronic gingivostomatitis
Neurological disease
Neoplasia
Myelosupression
5
5
How is FIV diagnosed?
Common to screen sick cats for FIV - detects antibodies
What if a kitten <6 months old tests positive for FIV?
Kittens may acquire maternal antibodies without FIV infection - retest at 6 months to check for antibodies again
Why should you always confirm a positive FIV result with another test?
FIV has major implications for the cat - must be kept inside for the rest of its life
Are false negative results for FIV possible? When?
Yes:
In early disease - takes up to 8 weeks for antibodies to become detectable
In terminal disease - antibody production may be impaired
In kittens with rapidly progressive disease - may have huge viral burden with minimal antibody response
What should you do if you suspect a false negative test result for FIV?
Re-test 2 months after initial test
OR
Get a PCR test done
Apart from symptomatically, in what situations should you test for FIV?
Known exposure to a FIV+ cat
Before rehoming to multi-cat household
Blood donor screening
Before vaccinating for FIV
What are the 3 possible outcomes when a cat becomes infected with FeLV?
Abortive infection - immunity
Regressive infection - effective immune response after spread
Progressive infection - manifestation of disease, persistent viraemia
What other conditions can occur as a result of FeLV associated immunosuppression?
Opportunistic infections (gingivostomatitis, upper respiratory infections, Mycoplasma haemofelis)
Impaired response to vaccinations
Anaemia/bone marrow disorders
Neoplasia
Which type of anaemia typically occurs with FeLV infection?
Macrocytic, non-regenerative (but regenerative also possible)
What haematological findings might there be with FeLV?
Non-regenerative anaemia (macrocytic)
Neutropenia
Thrombocytopenia
Severe and pre-malignant leukaemic bone marrow disorders
What types of neoplasia are most commonly seen as a result of FeLV?
Lymphoma (thymic)
Leukaemia
What ocular sign can be seen with FeLV?
Anisocoria (difference in pupil sizes)
How is FeLV diagnosed?
ELISA blood screening for FeLV antigen (capsid protein p27)
Immunofluorescent antibody (IFA)
PCR
What should the next steps be if a cat tests positive for FeLV?
Confirm result with different manufacturer/methodology (rule out false positives)
Are false negative results possible when testing for FeLV?
Yes - may take up to 1 month for antigen to be detectable
Re-test in 1-2 months if suspected exposure (but negative test)
Do maternal antibodies/vaccinations interfere with diagnosis of FeLV in kittens?
No - FeLV tests are for antigen, not antibodies
What is the treatment for FIV/FeLV?
No medication can clear virus from the body - more about supportive management and general nursing care
What supportive management/general nursing care should be provided to cats with FeLV/FIV?
Ensure well-hydrated
Adequate nutritional provision
Management of manifestation of disease (antibiotics, analgesia, anti-inflammatories)
Antiviral drugs may help
What home-management considerations need to be taken with FIV and FeLV cats?
Indoor-only with regular health checks
Vaccinate against core diseases (only inactivated vaccines)
Separate positive and negative cats (ideally)
Both viruses labile outside host - consider fomites
No hunting/raw food (infection risk)
How can FIV be prevented?
Vaccination (not fully protective) - only vaccinate seronegative cats
How can FeLV be prevented?
Vaccination (not 100% effective) - usually outdoor cats, multi-cat environments
What is the prognosis for FIV?
Sick positive cats <1 year
BUT
Healthy positive cats same life expectancy as negative cats
What is the prognosis for FeLV?
Regressive infection usually results in FeLV associated disease within 3-5 years
Once sick, prognosis/quality of life is usually poor
What is feline coronavirus (FCoV)?
A large, enveloped RNA virus
What does a low virulence feline coronavirus cause?
Gi infection but no disease
What does a medium virulence feline coronavirus cause?
GI infection +/- GI disease
What does a high virulence feline coronavirus cause?
Multi-systemic, fatal disease
has ability to infect macrophages
What is the prevalence of feline coronavirus in the cat population?
Up to 100% of cats in multi-cat households will be infected with FCoV at some stage (but with a low prevalence of clinical disease)
How is FCoV transmitted?
Faeco-oronasal transmission
Shared litter trays, faecally contaminated fomites
What other disease is FCoV able to mutate into?
Feline infectious peritonitis (FIP) - happens in very few cats (5%)
Where does FCoV replicate in the body? When it is shed?
Intestine - frequently without signs
Shed via faeces 1 week later
Does feline infectious peritonitis spread between cats?
Not usually
What are the 2 types of FIP? Why are there 2 types?
“wet” (more common)
“dry” (less common)
- depends on cats immune response
How do cats with “wet” FIP present?
Jaundiced, lethargy, inappetence, weight loss, pyrexia
Abdominal/pleural/pericardial effusions
How do cats with “dry” FIP present?
Development of pyo/granulomatous lesions within organs leading to organ dysfunction No effusions (may develop over time) Jaundiced, lethargy, inappetence, weight loss, pyrexia
Where can the pyo/granulomatous lesions develop in ‘dry’ FIP?
Lymph nodes Brain (neuro signs e.g. seizures) Eyes (uveitis, chorioretinitis) Intestines (focal granulomas) Liver Kidney (renomegaly)
Is there a test which can differentiate FCoV from FIP?
No - they are the same virus, only differ in their ability to cause multi-systemic disease/infect macrophages
What type of cats are more prone to FIP?
Young, pure-bred cats from multi-cat households, commonly <1 yr old
What examination findings would you expect to see in a cat with FIP?
Weight loss, poor condition
+/- effusions/ocular changes/neurological signs/palpably enlarged lymph nodes/kidneys/liver
What haematology changes may occur with FIP?
Lymphopenia
Non-regenerative anaemia
What serum biochemistry signs may be seen with FIP infection?
Increased globulin and bilirubin
Decreased albumin
Increased a-1 acid glycoprotein
What should you be looking for during ultrasound for suspected FIV?
Fluid - abdominal/pleural/pericardial effusion
Lymphadenomegaly
What is the most useful test to perform with suspected FIP?
Effusion analysis
What should you see on effusion analysis if a cat has FIP?
Thick, yellow, proteinaceous exudate Increased protein (globulin) Moderate cellularity (often neutrophils and macrophages)
What further tests can be done with FIP effusion fluid?
FCoV reverse transcriptase polymerase chain reaction
Immunocytochemistry (demonstrate FCoV within macrophages)
What tests can be done if the suspected FIP is not “wet”?
Wait and see if effusion develops
OR
Histopathology of grossly abnormal organs
Immunohistochemistry for macrophages
Why isn’t serology useful in diagnosis of FCoV/FIP?
Only demonstrates prior exposure - majority of cats are infected/carriers of FCoV
What is the treatment for FIP?
No treatment - nursing management aims at improving quality of life, many euthanised on diagnosis
Prednisolone or immunomodulators may help transiently
Is there a vaccine against FIP?
Yes - not currently advised as only licensed from 16 weeks and most kittens have already caught FCoV by this time
How can you rid FCoV from the surrounding environment?
Dispose of all faeces correctly
Susceptible to most disinfectants, including bleach
What steps should be taken in post-infection household management after a FIP death?
Inform the breeder
Wait 2 months before acquiring new cat
Reduce stress/overcrowding in multi-cat households
Ensure cleanliness
What considerations should breeders take to prevent FCoV/FIP?
Queens should kitten away from other cats
Consider early weaning (6 weeks)
Avoid repeat matings that have resulted in FIP kittens
Quarantine the household and avoid breeding for 6 months if there is a FIP case
What are the best preventative measures against FIP?
Do not re-home kittens too early
Temporally separate major events
Aim for single/small group cat households - avoid introducing new cats
Hygiene measures
What is Toxoplasmosis (Toxoplasma gondii)?
Coccidian protozoal parasite
What is the definitive host of toxoplasma gondii?
Cats
What are the intermediate hosts of toxoplasma gondii?
Most warm-blooded vertebrates, including cats and people
Is toxoplasmosis a zoonotic disease?
Yes
What is the definitive host of a parasite?
The host in which parasitic sexual maturity and reproduction occurs
What is the intermediate host of a parasite?
The host in which one (or more) stage(s) of parasitic development occurs
What is the transport host of a parasite?
A host in which the parasite may survive but no parasitic development occurs (may be a vector/vehicle for transmission to other hosts)
What are the 2 types of T. gondii oocysts?
Unsporulated form (non-infectious)
and
sporulated form containing sporozoites (infectious)
What do T. gondii oocysts produce when they undergo schizogony?
Asexual reproduction Produces merozoites (2 identical daughter cells)
How does T. gondii reproduce sexually?
Merozoites transform into macro or microgametes - microgametes penetrate the macrogamete to form a zygote (oocyst)
When are T. gondii tachyzoites produced?
During the rapidly dividing stage of infection (active infection)
When are T. gondii bradyzoites produced?
During the slow division/tissue cyst stage (latent infection)
What happens to bradyzoites if they are ingested by a cat?
They transform into merozoites within the GI tract
How are cats typically infected by T. gondii?
By hunting - ingestion of bradyzoites in prey tissues
How long are oocysts shed in the direct hosts faeces after ingestion of T. gondii bradyzoites?
Up to 3 weeks post-ingestion
What is involved in the immune response to T. gondii?
Production of IgM during acute infection and IgG during convalescence
What are the risk factors for T. gondii exposure?
Outdoor lifestyle
Faecal ingestion
Hunting
Higher age
What are the clinical signs of T. gondii infection?
Lethargy, anorexia
Ocular - uveitis, chorioretinitis
Neurological - CNS signs, neuromuscular disease
Other symptoms are location-dependent (pulmonary, hepatic)
Rarely causes GI signs
How is toxoplasmosis diagnosed?
Serology (IgG and IgM levels)
Cytology/histology - look for the organism in tissue/fluid
PCR
What is the treatment for toxoplasmosis?
Clindamycin, 4 weeks
Give with food/follow with water (oesophageal strictures)
What supportive management can be given for toxoplasmosis?
Analgesia and anti-inflammatories
Systemic prednisolone (some cases)
Nutritional/fluid support/anti-emetics
What is the prognosis for toxoplasmosis in cats?
Poor - esp CNS/hepatic/pulmonary involvement
Concurrent disease/immunosuppression increases risk of poor outcome
How effective is the treatment for toxoplasmosis?
Treatment suppresses replication - improves clinical signs but does not eliminate infection
How does T. gondii pose an infection risk to humans?
Ingestion of raw/undercooked meat
Lambing
Sporulated oocysts - resistant in environment
Initial infection in pregnancy risks foetal complications including stillbirth
What is haemoplasmosis?
A feline erythrocytic infection
How is haemoplasmosis transmitted?
Proven method not confirmed Possibly iatrogenic (transfusions), through arthropod vectors, or bite/fight wounds
What factors make a cat more likely to catch haemoplasmosis?
Males Outdoor access Non-pedigree Young FIV/FeLV positive
What is mycoplasma haemofelis also known as?
Feline infectious anaemia
How does mycoplasma haemofelis cause anaemia?
It is a cell surface pathogen, causes RBCs to be targeted for destruction by the immune system
How long is the incubation period for M. haemofelis?
2 days - 1 month
How long does acute haemolytic anaemia typically last in M. haemofelis infections?
2-4 weeks
What are the clinical signs of M. haemofelis anaemia?
Vary depending on severity
Weak, lethargic, inappetent, pyrexia
Pallor
tachypnoea
tachycardia, heart murmurs
+/- splenomegaly
Pica
What haematological findings are seen with M. haemofelis anaemia?
Regenerative anaemia - presence of reticulocytes
+/- autoagglutination (RBCs clumped together due to antibodies on surface)
How is haemoplasmosis diganosed?
PCR of blood sample
Blood smear examination not reliable
Why is a blood smear not sufficient to diagnose haemoplasmosis?
Infection can be cyclical - haemoplasmas not always visible on RBCs or may ‘fall off’
Many other features cannot be reliably differentiated from haemoplasmas e.g. Howell-Jolly bodies
What is the treatment for haemoplasmosis?
Doxycycline 2 weeks (for clinical remission - may not eradicate organism)
+/- blood transfusions
+/- prednisolone
Usually respond within a few days
Can dogs get haemoplasmosis?
Yes - canine-specific Haemoplasma spp.
Of rare clinical significance - splenectomised or immunocompromised dogs