Canine and Feline Infectious Diseases

define immune deficiency disorder

failure of immune system to acquire or sustain immunity thus increasing susceptibility to infection

what is the difference between a primary and secondary immune deficiency

Primary: genetic

Secondary: acquired (immune mediated, infectious, neoplastic) (most comon)

what is primary ciliary dyskinesia

immotile cilia dont beat mucous and bacterial/viral infections not cleared

causes recurrent bacterial pneumonia and nasal discharge

what are the three components of the immune system and name one disease process in each

1. barrier/mucosal (mucous, cilia, IgA, skin, chemicals)

- primary ciliary dyskinesia

2. innate (neutrophils. macrophages, complement)

- leukocyte adhesion deficiency

3. adaptive (Antibodies, cytotoxic T cells)

- SCID

describe pelger huett anomaly

1. deficiency of what system

2. breeds it effects

3. characteristics

4. effect

1. innate

2. australian shepards and cocker spaniels

3. nuclei of granulocytes are not lobed

4. usually normal

describe canine leukocyte adhesion deficiency :

1. deficiency of what system

2. breeds it effects

3. characteristics

4. effect

1. innate

2. irish setters

3. Mac 1 deficiency causes inability of neutrophils to extravastate out of endothelium

4. neutrophilia, fever, decreased healing, susceptible to infections

define canine cyclic neutropaenia

1. defieincy of what system

2. breeds it effects

3. characteristics

4. effect

1. innate

2. grey collies

3. cyclic neutropaenia every 11-12 days followed by recovery

4. platelet dysfunction, susceptible to infections

describe immune mediated neutropaenia

1. deficiency of what system

2. characteristics

3. treatment

1. adaptive

2. Ab destruction of neutrophils leading to severe neutrophil deficiency

3. glucocorticoids

define Erlichia canis

1. deficiency of what system

2. characteristics

3. symptoms

4. location

1. adaptive

2. bacterial tick borne disease (brown dog tick vector)

3. fever, LN enlargement, thrombocytopaenia, bone marrow suppression

4. endemic to NT, WA and north QLD

list some viral diseases that effect bone marrow

1. feline panleukopaenia

2. canine parvovirus

3. canine distemper

4. feline leukaemia virus

what are the 2 serotypes of feline coronavirus

Type 1

most common, worldwide

Type 2

resultant virus from recombination between type 1 FCoV and canine coronavirus

describe how feline enteric coronavirus progresses to feline infectious peritonitis

persistent infection of feline enteric coronavirus, undergoes mutation with altered tropism from epithelial cells towards monocytes

describe the epidemiology of feline infectious peritonitis host, agent, environment

host: <2 YO, purebred

agent: ubiquitous, chronic shedding

environment: overcrowded, unsanitary, stressful

what are the non specific clinical signs of feline infectious peritonitis

- fever

- lethargy

- anorexia and weight loss

- neurological

- uveitis

- papular lesions

- LN swelling

describe the clinical signs of the wet/effusive form of feline infectious peritonitis

- ascites

- thoracic and pericardial effusion

what pathology is seen in a cat with feline infectious peritonitis

- leukocytosis or leukopaenia

- anaemia

- elevated liver enzymes, urea and creatinine

what are the steps in diagnosing feline infectious peritonitis

1. good clinical history

2. clinical signs

3. imaging and analysis of any effusion

4. exploratory laparotomy and histopathology

5. advancing imaging and CSF analysis

discuss the treatments available for feline infectious peritonitis

Antiviral remdesvir

GS441524 tablets (best)

Mefloquine (more affordable)

how do retroviruses replicate

1. reverse transcriptase converts viral RNA to DNA

2. incorporated into host cell genome

3. cell produces viral proteins via transcription and translation of new viral DNA

why are retroviruses prone to mutation

high error rate of reverse transcriptase particularly with env genes

describe the pathogenesis of feline immunodeficiency virus in terms of:

1. transmission

2. serotype in Aus.

3. target cell

4. susceptible population

1. mainly cat bites

2. A

3. CD4 T cells and a lesser extent CD8 T cells

4. intact free roaming adult males (mixed breed and sick)

describe the primary, asymptomatic and secondary stage of the disease course of feline immunodeficiency virus

Primary (weeks)

- initial viraemia followed by decreased viral load as immune system keeps in check

Asymptomatic (years)

- CD4 drops and immunity begins to wane

secondary (months)

- increased viraemia

why is viral antigen of feline immunodeficiency virus not tested for, but the Ab instead

viral load is low and undetectable for most of disease course

after window period, FIV Ab remain consistently elevated

what are the clinical signs of feline immunodeficiency virus

- usually asymptomatic

- increased susceptibility to infection and lymphoma

- gingivostomatitis

what pathology are you likely to see on a cat with feline immunodeficiency virus

- hyperglobulinaemia

- mild anaemia

- neutropaenia

- thrombocytopaenia

describe the serological testing of feline immunodeficiency virus

- lateral flow ELISA

- often performed in combination with FeLV

what management options are there for a cat with feline immunodeficiency virus

- whole mouth extraction (severe stomatitis)

- Abx/fluids/supportive care

why is PCR not a suitable option for testing for feline immunodeficiency virus

less sensitive as viral load is low most of the disease course

do we vaccinate cats for feline immunodeficiency virus

No

- non core, reserved for high risk settings

what are the subtypes of feline leukaemia virus

A- wild type, transmitted

B- recombines with endogenous DNA-> B cell Lymphoma

C- point mutation in env gene-> non regenerative anaemia

D- mutation-> tumours

what cells to feline leukaemia virus target

lymphocytes and monocytes

what is the disease course of feline leukaemia virus

1. abortive

2. regressive

3. progression

what are the clinical signs of feline leukaemia virus

1. abortive- no signs

2. regressive- no signs unless reactivation occurs

3. progressive

- OI

- lymphoma and sarcoma

- pure red cell aplasia

- bone marrow suppression

- neurological disease

describe the testing and diagnostics of feline leukaemia virus

- lateral flow ELISA, repeated 30 days after exposure

- PCR for proviral DNA- test for abortive infection

what treatment options are available for feline leukaemia virus

- supportive

- chemo for lymphoma

do we vaccinate for feline leukaemia virus

- non core vaccine

- injection site sarcomas

what is the transmission of feline leukaemia virus

infects cat saliva and transmitted through grooming, licking and sharing bowls

Feline Immunodeficiency Virus

1. risk group

2. transmission

3. immunosuppression

4. diagnosis

5. prognosis

1. intact free roaming adult males

2. bites

3. causes immunosuppression

4. antibody detection

5. no shorter life expectancy

Feline Leukaemia virus

1. risk group

2. transmission

3. immunosuppression

4. diagnosis

5. prognosis

1. young, multiple cat households

2. close contact, transplacental

3. causes immunosuppression

4. antigen detection

5. die within 3-5 years

what factors increase risk of upper respiratory tract infections/snuffles

- indoor environment- poor ventilation

- crowding

- stress

- poor hygiene

- poor body condition

- retroviral infections

why is it difficult to eradicate upper respiratory tract infections/snuffles

- chronic carriers

- vaccination does not confer robust immunity

list some causes of upper respiratory tract infections/snuffles

- feline rhinotracheitis (feline herpes virus 1)

- feline calicivirus

- bordetella bronchiseptica

- idiopathic feline rhinosinusitis

what are the clinical signs of upper respiratory tract infections/snuffles

- sneezing

- nasal discharge

- conjunctivitis/keratitis/ocular discharge

- stomatitis/gingivitis

describe the pathogenesis of upper respiratory tract infections/snuffles

1. predilection for resp mucosa

2. cell injury/necrosis

3. inflammation and repair

4. carrier state

describe feline herpes virus in terms of

1. transmission

2. clinical signs

1. droplet spread

2. ocular lesions/sneezing

describe the difficulty of diagnosis of feline herpes virus in terms of

1. agent

2. PCR

3. serology

1. not always possible to identify agent

2. may be negative, may be detect vaccinated live virus

3. previous exposure does not indicate active infection, vaccination may interfere

how can you reduce spread of upper respiratory tract infections/snuffles in catteries/shelters (calicivirus and herpes)

- address overcrowding if possible

- hygiene

- vaccination of kittens and queens prior to breeding

- isolate sick cats

- quarantine new animals

what are the clinical signs of feline calicivirus

- severe mouth lesions

describe the treatment of feline calicivirus

- symptomatic and supportive (similar to herpes virus)

what are the issues with preventing feline calicivirus

- vaccine does not stop shedding

- does not prevent transmission, only reduce severity

what cells does canine parvovirus target

rapidly dividing cells such as intestinal mucosa and neutrophils/bonemarrow

describe the pathogenesis of canine parvovirus

damage to intestinal crypt cells stripping of intestinal lining and increased intestinal permeability leading to haemorrhaegic diarrhoea and intractable vomiting

what are the clinical consequences of canine parvovirus

- dehydration and sepsis

- neutropaenia

- death

what are the clinical signs of canine parvovirus

- young unvaccinated puppies

- purebreeds

- anorexia

- severe vomiting

- profuse watery to haemorrhaegic diarrhoea

how can we diagnose canine parvovirus

antigen lateral flow ELISA (snap test) matches clinical signs

- neutropaenia/hypokalaemia/hypoglycaemia

what are the management priorities for a puppy with canine parvovirus

- prevent spread (isolate, PPE, dedicated equipment)

- treat dehydration, hypovolaemia and electrolyte loss

- nasogastric tube to provide nutritional support

- prevent sepsis with Abx, regular changing of catheters

describe the treatment for a puppy with canine parvovirus

- IV fluids to maintain hydration

- potassium supplementation

- glucose IV

- Abx

describe canine distemper in terms of:

1. transmission

2. incubation period

3. susceptible population

1. oronasal route via resp secretions, vomit, faeces

2. 1-3 weeks

3. young unvaccinated dogs

what are the 3 clinical syndromes of canine distemper

acute

- fever, ocular/nasal discharge, diarrhoea, uveitis

subacute

- pneumonia, weightloss, neurological disease, enamel hypoplasia

chronic

- neurological disease and immunosuppression

describe the diagnosis of canine distemper

- clinical signs

- vaccination status

- possible exposure

- distension inclusion bodies in RBC

why is diagnosis of canine distemper difficult

- no pathognomic findings on blood analysis

- serology is complicated by vaccination (best in Aus)

- RT-PCR is complicated by vaccination

describe the treatment of canine distemper∫

- supportive fluids, feeding etc.

- antivirals not effective

what is the prognosis of canine distemper

dogs that survive mucosal disease and dont develop neuro signs from chronic disease have better prognosis

dogs that develop neurological signs have poor prognosis

describe the epidemiology of infectious canine hepatitis (blue eye) in terms of

1. viral cause

2. cell tropism

3. transmission

4. susceptible population

1. canine adenovirus type 1

2. endothelial cells, epithelium and hepatocytes

3. oronasal (not airborne)

4. unvaccinated puppies

describe the pathogenesis of infectious canine hepatitis

- spread via contact with contaminated surfaces

- replicates in endothelium and hepatocytes causing hepatitis, haemorrhaege

what are the syndromes associated with infectious canine hepatitis

1. systemic inflammatory syndrome

2. DIC

3. haemorrhaegic viraemic syndrome

what are the clinical signs of infectious canine hepatitis

- vomiting, fever and anorexia

- blue eye

- neurological signs, stuport and seizures

describe the diagnosis of infectious canine hepatitis

- unvaccination

- clinical signs

- PCR

describe the treatment of infectious canine hepatitis

- fluids

- monitor electrolytes

- monitor glucose

- feeding

(symptomatic and supportive care)

what is the prognosis of canine infectious hepatitis

- poor of neurosigns develop

what are the 3 canine viral diseases that are easily preventable by vaccines

1. canine parvovirus

2. canine distemper

3. infectious canine hepatitis

what are some aetiological agents that cause kennel cough

- canine parainfluenza, adenovirus type 2, herpes virus, distemper

bordetella bronchiseptica

describe the morbidity and mortality of kennel cough

highly contagious non threatening

what is the susceptible population for kennel cough

any age breed or sex that has had exposure

what are the clinical signs of kennel cough

- harsh dry unproductive cough

- bright and alert

- irritable trachea

what is the diagnosis of kennel cough

- clinical signs

- PCR

- serology complicated by vaccine

often not necessary to isolate agent as self limiting infection

what are the treatments available for kennel cough

- symptomatic treatment

- humidifier

- anti inflammatories

- antitussives

what prevention methods are available for kennel cough and how does this impact control

- systemic and intranasal vaccines

- vaccines only reduce severity not prevent transmission

- vaccines do not provide long lasting immunity

- dont stop shedding

- difficult to administer intranasal vaccines

describe the transmission cycle of leptospira

- contact with water bodies or maintenance hosts (rodents)

describe the pathogenesis of leptospira

- penetrates intact mm after contact with water bodies or incidental hosts

- effects kidneys and renal tubule damage, hepatic injury

- causes hypokalaemia

when should you suspect a diagnosis of leptospirosis

- farm dog from rural wet environment of FNQ

- presents with acute renal and liver failure, uveitis and occular lesions

describe the diagnosis of leptospirosis

- challenging to diagnose

- MAT microagglutination test (lab variation in performance)

- point of care ELISA (best)

- detects IgM Ab, does not give serovar

- detects acute infection faster then MAT

- PCR

- blood or urine, doesnt give serovar

- dark field microscopy

- not very sensitive, risky to personelle

how can you diagnose leptospirosis in unvaccinated clinical case

ELISA- +ve IgM is likely diagnosis

- PCR +ve- likely diagnosis

how can you diagnose leptospirosis in vaccinated clinical case

IgM and PCR +ve- need to confirm with MAT

what treatment is available for leptospira

- support liver, kidney and lungs with fluids, electrolytes and feeding

- Penicillin and doxycycline

- reduce zoonotic spread (PPE, catheterisation)

describe the prevention available for leptospirosis

- vaccination of correct serovar with annual boosters

- not a core vaccine

describe feline panleukopaenia virus in terms of

1. susceptible population

2. mortality

3. tissue tropism

1. young unvaccinated cats

2. highly fatal

3. gut, bone marrow, neurotissue in utero

what are the clinical signs of feline panleukopaenia virus

- diarrhoea

- vomiting

- dehydration

- anorexia

- fever

- pallor

describe the pathogenesis of feline panleukopaenia virus

- faecal oral transmission

- infects gut and bone marrow causing sloughing of intestines, haemorrhaege, lymphopenia, neuropaenia and anaemia

explain the diagnosis of feline panleukopaenia virus

- typical clinical signs in unvaccinated cats

- antigen point of care ELISA

what treatments are available for feline panleukopaenia virus

- fluid and electrolyte supplementation

- feeding (issue as tube feeding may create food eversion)

- antibiotics for secondary infections

what are the characteristics of an ideal vaccine

- safe

- induces robust immunity

- does not require frequent boosters

- good cross reactivity between strains

what kind of diseases respond well to vaccines

- systemic diseases

- low mutation rate of antigen

- antibodies are protective

- no sophisticated immune evasion strategies

describe modified live vaccines

- weakened form of infectious agent that induces very strong immunity

- more likely to cause side effects

- may cause actual infection in immune compromised individual

describe killed vaccines

- no live pathogen

- require adjuvants to make them visible to immune system

- induce weaker immune response

- less likely to cause side effects

describe recombinant vaccine

pathogen DNA is packaged into a vector

define core vaccine and provide examples

essential for all pets regardless of geographical location

- canine distemper

- canine parvovirus

- rabies

- feline calicivirus

- feline panleukopaenia virus

- feline herpes virus

define non core vaccine and provide examples

risk based administration

- bordetella bronchiseptica

- leptospira

- feine leukaemia virus

- feline immunodeficiency virus

what is the window of susceptibility in vaccines

as maternal antibodies decline, they reach a point that it is too low to prevent infection but high enough to interfere with seroconversion of vaccination

why do puppies/kittens have so many vaccinations

- unknown when animal successfully seroconverts and where the level of maternal immunity it at