How Do I Treat Nasal Herpes?

Feline herpesvirus (FHV-1) is a large virus (100-130nm in diameter), with an envelope and double-stranded DNA, which proliferates in the nucleus and forms intranuclear inclusions. Feline herpes virus is extremely unstable under acidic conditions, is very sensitive to heat, ether, chloroform, formalin, and phenol. It survives in a dry environment for no more than 12 hours. Therefore, the virus appears to be quite fragile in the environment. General disinfection Agent can effectively disinfect. The infected subject FHV-1 can only infect felines, and the virus has been isolated from dogs, but its importance is unknown.

Feline rash virus, also known as viral nasal bronchitis, is widespread throughout the world, and only one serotype has been identified, but its virulence varies among virus strains. Feline herpes virus replicates and proliferates in the conjunctival and epithelial epithelial cells, as well as in neuronal cells. Infection with neurons can lead to latent infections throughout the life, although feline herpes virus is antigen-associated with canine herpes virus Sexual, but it is unknown whether they will be transmitted to each other.

Feline herpes virus is susceptible to many commercial disinfectants and cleansers. It is not activated within 3 hours at 37 ° C and not activated within 5 minutes at 56 ° C. It is still infectious at 4 ° C, and It lasts for at least 5 months, and maintains infectivity at 25 ° C for about one month.

Chronic latent infection is a typical result of acute infection with feline herpes virus, and is intermittently reactivated, causing the virus to be discharged in the oral and nasal and conjunctival secretions. Unless it is kept in a cat house, environmental pollution is not the main source of infection. The main source of infection is cats in acute infection period and cats with chronic latent infection and reactivation of detoxification. The possibility of a placental infection has not been confirmed, but chronic latently infected female cats are considered an urgent state during childbirth and lactation, so they will cause the virus to reactivate and begin to emit the virus. Therefore, young cats may be exposed to the virus very early. . However, the result of infection depends on the amount of the mother's migration antibodies. When there is sufficient migration antibodies, cats will be protected by the migration antibodies, so asymptomatic infection will form and a latent infection state will be formed. If the migration antibodies are insufficient, There may be clinical symptoms.

In healthy small ethnic groups, the incidence of viral emissions may be less than 1%, and in large symptomatic populations, the incidence of viral emissions may reach 20%. Such a low incidence of viral emissions may reflect The characteristics of intermittent virus discharge from latently infected cats, but if it is in the shelter, the risk will become higher. After 4% of the cats entering the shelter, after one week, up to 50% of the cats may emit virus ^[1]

The virus enters the cat's body through the mouth, nose, and conjunctiva, and then causes lytic infection of nasal mucosal epithelial cells, which then spreads to the conjunctiva, throat, trachea, bronchi, and small bronchi. The focus is local multiple necrosis (neutrophil Neutrophil infiltration) and inflammatory lesions. There have been reports of transient viremia, especially in newborns or hypothermia, as feline herpes virus prefers to replicate at lower temperatures. The virus started to be released 24 hours after infection, and lasted for 1-3 weeks. The acute disease would be relieved within 10-14 days, and some would form chronic lesions of the upper respiratory tract and eyes.

The virus spreads along the sensory nerves and reaches neurons, especially in the trigeminal ganglion, where the main latent infection is located, and almost all infected cats become life-long poisonous. At present, there is no simple test method to determine this latent state, because the virus genes will exist in the nucleus of infected neurons and do not replicate. About 70% of infected cats can induce virus reactivation through steroid administration. And detoxification, other pressing factors that may induce virus reactivation include lactation (40%) and environmental change (18%).

Some adult cats may form lesions during the period of virus reactivation. We prefer to refer to diseases that are caused by virus reactivation as recrudescence. Conjunctivitis may be accompanied by corneal ulcers and may form chronic corneal osteomalacia. Stromal keratitis is a secondary immune-mediated response because the virus is present in the corneal epithelial cells or the stroma. If acute cases cause damage to the turbinate, it is easy for some cats to develop chronic rhinitis ^[1]

Feline herpes virus infection is common and can cause serious and fatal illnesses, so it is considered a core vaccine, and it is recommended that all cats be vaccinated ^[1] .

Disease control for feline herpes virus special conditions

1. Shelter

The condition of feline herpes virus infection is particularly serious in the shelter, so how to control the infection is as important as vaccination. If a new cat is immediately mixed with the original cat, the infection rate must be very high, so the new Cats must be quarantined separately for two weeks, if they are from the same family, they can be together. The design and management of the shelter should focus on avoiding cross-contamination. New cats should be vaccinated as soon as possible. If the shelter is at high risk of infection, it is recommended to receive a weak vaccine because it can provide protection early. In the case of respiratory diseases, laboratory tests should be performed immediately to distinguish between feline herpes virus and feline calicivirus, which will help in the design of appropriate precautions.

2, breeding ground

For many breeding grounds, feline herpesvirus infection can be a major problem. Most of the infection problems that occur are in young cats before weaning, 4-8 weeks of age. At this time, when the migrating antibodies started to weaken, most of the viruses originated from the mothers who were latently infected by the urgent production and lactation. Clinical symptoms can be severe and all kittens are infected and may cause death, while some recovered kittens may develop chronic rhinitis. Maternal vaccination does not prevent this problem, because vaccination does not prevent the mother from becoming a carrier, but if the mother has a high antibody titer, then the colostrum's migrating antibodies will help provide the cat's initial pediatric weeks. Protective effects, so regular vaccination of female cats is necessary and should be done before breeding. Feline herpes virus is not recommended during pregnancy. Inactivated virus vaccines should be used even if they are vaccinated, but only with a few exceptions.

Breeding management plays a decisive role in the control of feline herpes virus infection in the cat house. Female cats should be produced in isolation. The kittens born should not be mixed with other cats until the vaccination is completed. When several fetuses have been confirmed to infect the kittens, the kittens born to it must consider early vaccination. The minimum age for vaccination of feline herpes virus vaccine in the instructions is 6 weeks, but it can be considered to be inoculated around 4 weeks of age. Because you are already immune at this point, you need to strengthen it every two weeks until the normal vaccination plan begins.

3.Immunosuppressed cats

Vaccination cannot produce an immune effect under conditions of impaired immune function, such as systemic diseases, virus-induced immunodeficiency, nutritional deficiencies, congenital immunodeficiency, treatment with immunosuppressive agents, or prolonged urgency Although it is best for such cats to avoid contact with pathogens, it may not be completely avoided, so vaccination must also be considered, but an inactivated inactivated vaccine is recommended.

4.Cat leukemia or cat AIDS-positive cat

Even healthy leukemia or AIDS-positive cats should be protected against nasal bronchitis. Because it is quite difficult to completely restrict their activities in the home environment, they must be vaccinated to obtain protection. Some people worry that vaccination will worsen cat AIDS, but there are too many other infections that can make cat AIDS worse than vaccination. The benefits of vaccinating against upper respiratory tract diseases far outweigh their possible disadvantages; even if AIDS-positive cats may be carriers of upper respiratory tract diseases (herpes virus, calicivirus), you must also consider vaccination to maintain your cat In a stable state. As with any systemic disease, vaccination is not recommended if the cat is sick and has cat-AIDS-related illnesses.

5. Chronic diseases

If the cat's chronic disease is under stable control, such as hyperthyroidism or chronic renal failure, vaccination is still recommended. Cats treated with steroids or other immunosuppressants

Depending on the dose and duration of the medication, steroids can cause immunosuppressive effects, so steroids should be avoided during vaccination ^[1] .

Feline herpes virus vaccination recommendations

Feline herpes virus vaccine can induce antibodies and cellular immunity, but like other respiratory-restricted diseases, feline herpes virus vaccine's protective effect against clinical symptoms is not complete (an experimental challenge shortly after vaccination can reduce about 90% % Clinical severity), under the condition of extreme challenge or in the face of immunosuppression, the protective effect of vaccination will be poor, and no variant virus strain of feline herpes virus can be escaped at present The protective effect of vaccines ^[1] .

The protection provided by the vaccine is against disease, but may not be able to fight infection, but it can reduce virus emissions in the face of infection.

The feline herpes virus vaccines currently on the market are bivalent vaccines mixed with feline calicivirus, or more multivalent vaccines mixed with other pathogens (such as three-in-one, five-in-one), and inactivated. Both attenuated vaccines and attenuated vaccines are available, but attenuated vaccines still have certain virulence, which may cause clinical symptoms by accident (vaccination of the vaccine fluid by accidental inhalation by cats, or fluid adhesion to cat skin).

The predictive value of serological tests after vaccination for protection is very limited, because even after the cats have not been seroconverted (antibodies), they still have a protective effect (cellular immunity) and they are vaccinated. Afterwards, even if the antibody titer continues to drop to a very low level, when the pathogen is contacted again, a large amount of antibodies can be produced quickly and for a long time. This phenomenon is called anamnestic response ^[1] .

1.The initial vaccination schedule

The international feline medical society recommends that all kittens should be vaccinated with feline herpes virus. The mother's migratory antibodies may interfere with the immune response to vaccination, so the initial vaccination usually recommends a second dose at about two months of age. After two weeks, the vaccine has been considered to produce sufficient protection. If adult or young cats cannot confirm whether they have been vaccinated before, it is still recommended to administer two consecutive doses at intervals of 2-4 weeks ^[1] .

2. Regular reinforcement

If the cat is in a high risk of infection, it is recommended to strengthen it once a year. If the cat is kept indoors and stays at home, it can be vaccinated once every three years, but those cats who go out regularly to take a bath or visit the hospital often It should be considered high risk. Some experimental studies have found that most cats can protect against feline herpes virus for up to one year after vaccination, but investigations in the field have found that many cats are not. Most cats can An adequate antibody titer was measured to combat feline calicivirus and feline blast, or an anamnestic response occurred after the vaccine was boosted, but 30% of them did not detect feline herpesvirus antibodies, and about 20% There is no recall response after booster vaccination, so it is very difficult to determine how long the protection can be provided after vaccination, but it is certain that vaccination does not give cats 100% protection against feline herpes virus , Even after a short time after vaccination, and this protective capacity gradually decreases over time.

If the time of the booster vaccination is delayed, if the time of the last vaccination is not more than three years, it is only necessary to apply it once, but if it is more than three years, it is recommended to apply it twice, with an interval of 2-4 weeks ^[1] .