Feline Vaccines

feline injection-site sarcoma (FISS)

• Vaccine-associated sarcoma was first recognized as an issues in cats in the early 1990s

• Current risk below 1/10,000 dose of vaccine (very low)

• Initial reports: development of sarcomas at vaccination sites inactivated (killed) rabies or FeLV vaccines, and aluminum-based adjuvants

• Early identification and surgical removal (3-5 cm margins + 2 fascial planes deep) in the event fibrosarcoma is confirmed

• All recombinant and MLV feline vaccines sold in the US and Canada are adjuvant- free

feline core vaccines (AAHA/AAFP 2020)

• Feline Panleukopenia virus (FPV)

• Feline Herpesvirus1 (FHV1)

• Feline Calicivirus (FCV)

• Feline Leukemia Virus (FeLV)*

• Feline Rabies Virus

• Feline Infectious Peritonitis #

→ *for cats under 1 year of age

→ #not generally recommended

feline herpesvirus 1 (FHV 1) & Feline Calicivirus

• Upper respiratory complex

• Rhinotracheitis: inflammation of the conjunctiva; discharge from the eyes and nose

• Highly contagious

• Calicivirus

• Ulcerations and blisters in the mouth and the tongue

• Widespread and highly contagious

feline respiratory disease complex

• Feline viral rhinotracheitis (FVR; feline herpesvirus type 1), feline calicivirus (FCV), Chlamydia felis, Mycoplasma felis, or combinations of these infections: exotic and domestic species.

• Natural transmission: via aerosol droplets/fomites, which can be carried to a susceptible cat by a handler

• Convalescent cats may harbor virus for many months.

• Calicivirus is shed continually, infectious FVR virus is released intermittently.

• Stress may precipitate a secondary course of illness.

• Incubation period: 2–6 days for FVR, FCV; 5–10 days for pneumonitis [Feline pneumonitis (Chlamydia psittaci)]

two types of modified-live virus FVR-FCV vaccines

• The first type: parenteral administration

• The second type: to healthy cats by instillation into the conjunctival cul de sacs and nasal passages; cats inoculated oronasally may sneeze frequently for 4–7 days after vaccination. Faster protection: high risk population and with kittens against respiratory disease Annual revaccination: single dose is recommended

feline panleukopenia virus (FPV)

• “Feline distemper”: highly contagious, often fatal

• The causative parvovirus very resistant: 1 year at room T° in the environment, if protected in organic material; transported long distances via fomites (shoes, clothing); peroxygen disinfectants

• Virus particles: all secretions/excretions during the acute phase of illness; shed in the feces of survivors for as long as 6 week after recovery

• Incubation period: 2–7 days

• Cats infected oronasally: infected animals, their feces, secretions, or contaminated fomites free-roaming cats

• Currently diagnosed infrequently by veterinarians: widespread vaccine use

• Infects and destroys actively dividing cells bone marrow, lymphoid tissues, intestinal epithelium; very young animals: cerebellum and retina.

• Fever, lethargy, anorexia, vomiting, diarrhea, marked leukopenia (secondary bacterial infections)

• When pregnant queens are infected in early/mid pregnancy: stillbirth is the usual result. Infection late in pregnancy: kitten "cerebellar hypoplasia”

FPV attenuated vaccines

vaccination of pregnant queens and kittens < 4 weeks of age should be avoided because of the theoretical concern for cerebellar hypoplasia; theoretical risks of clinical signs due to residual virulence for immunocompromised animals: avoid them in cats with retrovirus infection

inactivated FPV vaccines

likely safer in pregnant cats and those with retrovirus infections

Feline Leukemia (FeLV)

• FeLV, HIV retroviruses; reverse transcriptase inserts copies of their own genetic material into that of the cells they have infected.

• FeLV is more commonly spread from mother to kittens.

• The virus can also be spread between cats that live together or those that fight.

• It is mainly spread in saliva during grooming and when food and water bowls are shared.

• The virus is less often spread through urine or feces.

• In North America, 4% of tested cats are found to be infected with the virus; America Latina up to 42%

• Three varieties of FeLV infection: FeLV-A (naturally infected cats), FeLV-B, FeLV-C, and FeLV-T

• After oronasal inoculation: → oropharyngeal lymphoid tissue → blood mononuclear cells → spleen, lymph nodes, GI and bladder epithelial cells, salivary glands, bone marrow.

• Viremia: 2-4 weeks after infection; acute stage: 2-6 weeks after infection: mild fever, malaise, lymphadenopathy, blood cytopenias.

• Cats unable to mount an adequate immune response: persistently viremic, progressive infection (fatal disease).

• Oncogenesis: when FeLV virus inserts into the host cellular genome

• The most common cause of cancer in cats (Family Oncovirine): lymphoma, leukemia, various blood disorders (anemia), immune deficiency (secondary infections)

• No treatment available

• Diagnostic tests (ELIZA)

• Consider FeLV vaccination of uninfected cats (FeLV-negative cats): FeLV antigen testing (-p27- and not antibody testing); there is not proven benefit to vaccinating infected cats

• Vaccinations recommended for all kittens, again one year later, and regularly for cats that have access outdoors.

• Adult indoor-only cats living alone or with uninfected cats may not need to be vaccinated after the first 2 years

Feline Leukemia spread

• High quantities in saliva, nasal secretions, but also in milk from infected cats (horizontal and vertical transmission)

• Cat-to-cat transfer: bite wound, during mutual grooming; shared use of litter boxes/feeding dishes

• Transmission from an infected mother cat to her kittens, either before they are born or while they are nursing

• FeLV not survive long outside a cat's body: less than a few hours under normal household conditions

Feline leukemia: mgt of infected cats

• Infected cats may have a good quality of life: many cats die within 3 years of diagnosis, others clinically healthy for many years

• Preventive vet care: frequent PE, laboratory monitoring, core vaccination, spay/neuter surgery, dental prophylaxis, parasite control

• Avoid transmission to other cats by preventing access to outdoors and other uninfected cats in household

feline non-core vaccines

• Chlamydophila felis [Chlamydia psittaci (feline strain)]

• Bordetella bronchiseptica

• Feline Leukemia Virus (FeLV)*

• Feline Infectious Peritonitis (FIP) #

bordetella bronchiseptica

• Highly contagious respiratory disease (bacterial): inflammation of the trachea and bronchi.

• The clinical signs very similar to those of viral upper respiratory tract disease and there is mounting evidence that infection is widespread

• Easily spread through direct (licking, nuzzling) or indirect contact (air: coughing or sneezing)

• Transmission can occur between dogs and cats.

• The disease is most severe in kittens (where fatal bronchopneumonia has been reported).

More common than previously supposed: seroprevalence rates ranging from 24% to 79%

chlamydophila felis

• Bacterial: “Feline Pneumonitis”, however, most symptoms: eyes (conjunctivitis) or the upper respiratory tract (nose/throat)

• Because Chlamydia lives inside cells of the body and is not able to survive for long in the environment, spread of infection relies on direct or close contact with an infected cat (aerosol, fomites)

• Young cats and kittens: one of the most common causes of infectious conjunctivitis in cats

• Following infection, the incubation period is 3-10 days → conjunctiva (mucosal tissue)

• Intense conjunctivitis with extreme hyperaemia of the nictitating membrane, blepharospasm and ocular discomfort → watery discharge, mucopurulent; chemosis (edema) of the conjunctiva.

• Infected cats develop ABs and kittens appear to be protected initially for the first 1-2 months of life by MDA

• If one cat in the home is diagnosed with a C. felis infection: all cats in the household should be treated.

• Zoonotic risk: on rare occasions, C. felis: isolated from people living with infected cats and guinea pigs. Follicular conjunctivitis: one immunocompromised person that was found to be infected with C. felis.

Routine hygiene practices (washing before and after handling sick pets), may reduce the potential for transmission from affected animals to people

feline infectious peritonitis (FIP)

AAHAA/AFP lists the FIP vaccine as not generally recommended

• This vaccine is labeled for administration from 16 weeks of age, whereas many kittens become infected with coronaviruses well before this age.

• It also contains a serotype II strain of FIP virus.

• Serotype I FIP virus strains predominate in the field and do not have cross-reactive neutralizing epitopes with serotype II strains.

• Therefore, as noted in the previous iteration of the AAHAA/AFP guidelines there remains insufficient evidence that this vaccine induces clinically relevant protection in the field

FIP: immune-mediated disease triggered by infection with a feline coronavirus (FCoV)

• “internal mutation theory” (FCoV) & “viral genetics/host immunity theory”; other felid species susceptible; FCoV: important pathogen in nondomestic felids (cheetah)

Although the prevalence of FCoV infection is very ↑ in multicat households, <5% of cats in these situations develop FIP; lower in a single cat environment

• FCoV via fecal-oral transmission (inhalation -rare-): viral replication site intestinal epithelium → diarrhea in some cats.

• In many cats, infection for weeks to months with NO clinical signs; these cats shed FCoV either intermittently or continually (source of infection for other cats)

• Clinical signs of FIP depending on organ involvement: liver, kidneys, pancreas, CNS, eyes

• Susceptibility to FIP a polygenic inherited trait: Persians, Birmans; breeds with higher prevalence of FIP: Rex, Abyssinian, Bengal, Birman, Himalayan, Ragdoll

the “wet” effusive / exudative form of FIP

immune complexes aggregate in blood vessel walls, leading to vasculitis and subsequent leakage of fluid. “Pendulous Abdomen” (ascites)

the “dry” non-effusive / non-exudative FIP

multiple granulomas or pyogranulomas in various sites (e.g., lungs, liver, kidneys, intestines and CNS: anisocoria)

FIP Rivalta test

• Rivalta test: to differentiate between effusions caused by FIP and effusions caused by other diseases. The high protein content and high concentrations of fibrin and inflammatory mediators lead to a positive reaction; water and acetic acid + one drop of the effusion

• If the drop disappears and the solution remains clear: Θ.

• If the drop retains its shape, stays attached to the surface, or slowly floats down to the bottom of the tube (drop- or jelly-fish-like): ⊕

FIV Vaccine

• It was considered a non-core vaccine: administered on a case-by- case basis, depending on an individual cat’s risk of infection.

• The vaccine contained certain strains of inactivated (killed) virus, which offered protection against some (but not all) FIV infections; certain geographic areas, like UK: the vaccine offered little-to-no protection.

• The vaccine also needed to be readministered on a yearly basis.

• But the FIV vaccine contained adjuvants (additives that stimulate the immune system): concerns of vaccine-site sarcoma, a type of cancer that can develop at the injection site when a vaccine contains adjuvant

• Infected cats may appear normal for years (lentivirus). Infection eventually leads immune deficiency; median survival time for a cat diagnosed with FIV: ∼ 5 years.

• No treatment available

• Although FIV is similar to HIV (human immunodeficiency virus) and causes a disease in cats similar to AIDS, it is a highly species-specific virus that infects only felines

• Secondary and opportunistic infection respiratory tract, GI, urinary tract, skin

• Previous vaccinations do not prevent infections; preventing exposure, even for vaccinated pets; vaccination may have an impact on future FIV test results

• Diagnostic tests (ELIZA, PCR): positive (vaccination, infected cat; kittens from infected mothers) and negative (not infected cat; the cat’s immune systems is so compromised: no longer production detectable levels of ABs)

Many FIV-infected cats are not diagnosed until after they have lived for years with other cats: all the other cats in the household should be tested

FIV transmission

• Transmission: saliva, bite wounds (free-roaming, outdoor, aged male)

• Casual, non-aggressive contact: not an efficient route (household cat stable social structures low risk)

• On rare occasions: from an infected mother cat to her kittens (birth canal, infected milk)

• Sexual contact is not a major mean of spreading FIV

• In North America, about 3 to 5% of tested cats are found to be infected with FIV.; America Latina up to 25%

• All infected cats: separated from the non-infected ones (if fighting or rough play is not taking place: low risk to the non-infected cats)

• FIV not survive outside the cat for more than a few hours in most environments. However, FIV-infected cats are frequently infected with other infectious agents

• Clean and disinfect (dilute household bleach solution) or replace food and water dishes, bedding, litter pans, and toys.

Any new cats or kittens should be properly vaccinated against other infectious agents before entering the household

FIV symptoms

• Early in the course of infection: virus→ lymph nodes, where it reproduces in T-lymphocytes → fever.

• An infected cat's health may deteriorate progressively or recurrent illness with periods of relative health.

• Poor coat condition, persistent fever with a loss of appetite

• Gingivitis and stomatitis; persistent diarrhea

• Some cats: seizures, behavior changes, neurological disorders

• Slow but progressive weight loss, often followed by severe wasting late in the disease process.

• Several kinds of cancer, blood diseases

FIV vaccine summary

• Between 2002 and 2015, an inactivated (killed) whole-virus vaccine was available in North America that interferes with antibody results using some test kits

• FIV-vaccinated cat may test antibody positive for more than 7 years after the last vaccination

• Additionally, cats may travel from locations where the vaccine is still in use to the USA, Canada, and other countries where the vaccine is not available; rapid in-clinic test kits to differentiate between FIV-infected and FIV-vaccinated cats are available

dermatophytosis

• Microsporum canis: the most common fungal infection in cats; one of the most important infectious skin diseases

• M. canis produces arthrospores that may remain infective for about 1 year; easily transmitted: direct contact/fomites to cats, other animal species and humans (zoonosis).

• Many cats are infected subclinically or are fomite carriers of the arthrospores.

• Circular alopecia, desquamation, sometimes an erythematous margin around central healing (“ringworm”)

vaccination of sheltered-house cats

Limited to those diseases that are likely to be transmitted within the shelter itself

(FPV and upper respiratory infections)

• Earlier age, shorter intervals vs. pet cats

• Rapid onset of protection is critical: FPV, FHV-1, FCV vaccines should be considered for all cats at the time of (or ideally, before) intake.

• Rabies Vaccine: single dose at the time of entry or release

• FeLV Vaccine: single dose at the time of intake if group-housed

• Bordetella bronchiseptica and Chlamydophila felis: limited benefit; cats and dogs contacts

• FIV and FIP: generally not recommended

• Dermatophytosis vaccination: no vaccines available in the USA

montgomery county shelter core vaccines

• FVRCP: feline viral rhinotracheitis, calicivirus, panleukopenia

• Shelters that do not vaccinate with core vaccines immediately on entry, or do not vaccinate all animals: more likely to experience deadly outbreaks of vaccine-preventable disease

• Vaccinate against rabies when a long-term stay is anticipated; when risk of exposure is elevated; or when mandated by law

• Re-vaccination for kittens (FVRCP ) at 2-3 week intervals for the duration of their shelter stay or until they are over 18-20 weeks old

vaccination of cats in trap-neuter-return programs

Advisory Panel (AAFP, 2013): cats in TNR programs should receive FPV, FHV-1, FCV, and rabies vaccines at the time of surgery

vaccination of cats housed in breeding catteries

Limited to those diseases that are relevant to the cattery and determined by risk factor analysis

– Rate of population turnover

– Population size and density

– Number of litters/year

– Presence of endemic disease

• Catteries assessed as:

– “low risk” similar to pet homes

– “high risk” similar to shelters

• In high-risk environments: earlier age vaccinations,

shorter intervals (endemic upper respiratory tract disease)

vaccinations for foster cats

• Kittens or adult cats temporarily housed for rescue, rehabilitation, and rehoming purposes.

• The most important point: ensuring that the permanent population of the household is appropriated vaccinated to provide protection from disease exposure originating with foster cats