Infectious dz: Cat 3 Flashcards
What feline virus is worldwide and accounts for the most disease related deaths in pet cats?
Feline leukemia virus
retrovirus (needs DNA for replication)
What tissues does FeLV replicate in?
Bone marrow, salivary glands, respiratory epithelium
T/F: Endogenous FeLV passed down from mother to kitten is non pathogenic
TRUE
Exogenic FeLV that is passed horizontally from cat to cat is pathogenic and infectious –> FeLV-A
Cats who have endogenous inherited FeLV are more prone to get the pathogenic form
What is the FeLV associated gag protein that is produced in large quantities in infected cats?
gag protein P27
this is used as the antigen to test for FeLV infections
What cats are more likely to get FeLV, young or adult cats?
Adults - since they have more time for exposure
Outdoor cats and male cats are of greater risk
What is the mode of transmission of FeLV?
Close contact virus shedding
Saliva (predominantly) and blood
Vertical spread possible when queen is viremic (transplacental or nursing)
T/F: FeLV is very stable in the environment
FALSE
It is readily inactivated in the environment and easy to clean/disinfect
What is an abortive type FeLV infection?
Cats that have very high neutralizing effects - once they get exposed to the FeLV antigen their immune system will immediately destroy it.
These cats will never get infected and will always test negative for FeLV antigen
What is a regressive type FeLV infection?
cats test positive - then will become and test negative in a few months (3-6 weeks)
- once the virus begins replicating in the cells the immune system will kick in and stop any more replication
- The virus will still be present in their genome - but the viremia will be cleared
- if the cat becomes immunosuppressed - the virus could become active again (or in pregnancy)
- The cat will always be PCR positive for FeLV - but will be Negative for the p27 antigen
What is a progressive type FeLV infection?
These cats do not have a properly functioning immune system
the virus will replicate and spread all over
- these cats remain viremic (positive for FeLV antigen)
- tend to die within 3 years
What is an atypical or focal type FeLV infection?
Not really seen in clinical practice
noted in lab/virus induced animals - where the virus will be restricted to certain tissues like the spleen, LN, Small intestine, or mammary glands
(p27 antigen positive OR negative)
What clinical signs are associated with FeLV?
Hematopoietic malignancy, myelosuppression, infectious dz, various co-infections, Fading kitten syndrome (born with fatal viremia), neuropathy
What modes of diagnostic testing are used to diagnose FeLV ?
Direct detection of the virus - Look for p27 antigen using ELISA
*Direct FA testing
PCR (this will be positive even in a regressive cat - but could be helpful to link lymphoma to a previous FeLV infection)
T/F: Antibody detection is a good method to diagnose FeLV
FALSE
useless - immune cats will have antibodies
Antigen testing is ideal (p27)
what is the treatment for regressive FeLV positive cats?
Separate from FeLV negative cats and confine indoors to prevent spread to other cats
- good nutrition and husbandry
- exam, blood work, fecal, urine culture - yearly to ensure no underlying infections
(if the cat can not be separated from other FeLV NEG cats - the Neg cats should be vaccinated)
T/F: FeLV positive cats with tumors have a worse prognosis than FeLV negative cats with tumors
TRUE
since they will have a decreased immune tumor fighting capabilities.
Treatment however, will not be different
T/F: Most hematological disorders caused by FeLV are not reversible
FALSE
Most are reversible
- blood transfusions
- Recombinant human EPO injections (required daily)
- Darbopoietin (long acting EPO synthetic injection required monthly)
- Granulocyt colony stimulating factor for patients with neutropenia ($$$$$$)
What is the treatment for progressive FeLV infections?
Antiviral chemotherapy (Zidovudine, didanosine) - anemia can be a side effect: CBCs should be checked routinely
Immunomodulatory therapy: Feline Interferon to stimulate the cell mediated immunity (T cells) –> this therapy will decrease clinical signs and increase life expectancy
What cats are more susceptible to Feline Immunodeficiency virus? (FIV)
outdoor cats and cats in high population densities
Males
Adults are more susceptible than kittens
How is FIV transmitted?
Parental inoculation of virus in saliva or blood (**bite wounds)
(experimentally all parental routes)
Transmission through the mucosal route is RARE
Transmission from mother to kitten in utero or postpartum is VERY RARE
FIV is found in high concentrations in milk; why don’t the suckling kittens get infected?
It does not go through their MM and then gets denatured in the GI tract
T/F: The younger a cat is when he/she gets infected with FIV - the sooner they will show clinical signs and as a result die sooner
TRUE
A stray kitten is brought into your clinic, and you estimate it is 8 weeks old. The FIV test comes back positive, is this a death sentence for the kitten?
NO
The kitten may have maternal antibodies against FIV
These can last up to 6 months. The kitten should be retested after that time
The FIV virus is initially cleared by _______. Virus replication occurs in target tissues rich in ______
Cleared by macrophages initially
Replication occurs in tissues rich in lymphcytes - thymus, spleen. LN
When are viral antibodies able to be detected post FIV infection?
2 -4 weeks post infection
after initial viremia the host will mount an antibody response
What occurs in the asymptomatic period of the FIV infection?
The virus still continues to infect additional cells
plasma levels of virus and viral RNA will increase from time to time
T/F: FIV affects the cell mediated and humoral immunity, so CD8 and CD4 cells will be affected
TRUE
this can disrupt the normal immune function
What clinical signs may be seen in the acute stage of FIV?
this is during initial viremia
fever, malaise, +/- secondary infections, lymphandenopathy, enteritis, resp. tract disease, stomatitis, dermatitis
What clinical signs are seen in the terminal phase of FIV infection?
This is feline AIDS. It occurs after the cat goes through a clinical asymptomatic phase
*secondary infections, neurological signs: behavior change, seizurews, paresis, multifocal motor abnormalities,
Ocular dz - anterior uveitis (usually secondary to toxoplasma)
Neoplasia - lymphoma or leukemia
The most effective ELISA snap test for FIV is looking for _________?
ANTIBODIES
What changes may be noted on the bloodwork of an FIV positive patient?
neutropenia and lymphopenia
Anemia
Hyperglobulinemia
What tests can be done to confirm FIV in a cat?
ELISA - antibody testing
(ELISA antigen is not routinely used and PCR may have false positives - bc the virus undergoes many changes while in the body)
T/F: Kittens may have FIV antibodies from their mother, so if they have a positive test, they should retest at 4 months
FALSE
It is true kittens can have FIV antibodies from their mother - but those can be present until the kitten is up to 6 months old. Retest after 6 months
If you fear a cat has been exposed to FIV - how long should you wait before testing that cat?
60 days post potential exposure - this ensures there will not be a false negative result in the early stage of infection
What treatment is recommended for FIV positive cates?
Antiviral chemotherapy
AZT (zidovudine) - improves quality of life and prolongs life expenctancy
**regular CBCs should be done as a side effect is anemia
Immunomodulatory therapy: Interferon alpha - stimulates the immune system
What management protocols should be considered with FIV positive cats?
Keep cats strictly indoors Feed a balanced diet Avoid raw meat and milk Proper flea, tick, and parasite control Treat underlying infections immediately
T/F: The FIV vaccine provides total immunity against the virus
FALSE
single strain vax only protect against that specific strain
New vas with subtype A and D that is promising for a broad spectrum virus neutralising antibodies
