Herpes Virus or Rhinotracheitis in Catteries, Shelters and Multi Cat Households

Herpes and calicivirus and Kittens

Question: Dr. Richards:

I am expecting the first of 5 litters of kittens this weekend since the outbreak of herpes in my cattery and have a few more questions. Thank you in advance for your help and your timely response.

1) I was under the impression that kittens were given some immunity at birth from the herpes virus from the Mom cat. In reviewing the information on your web site, you responded to a client as follows: "Kittens do not seem to get much effective immune protection from their mothers, who are often stressed by the birth and lactation periods and therefore may be shedding the virus." How are we to protect the kittens from Day 1 until Day 10 when the eyes come open and we can administer the heska vaccine? Or is it unlikely that the kittens would get sick that quickly due to an incubation period? Have you had other breeders give you any feedback on this?

2) Somewhere along the line, we had heard from a vet that the Mom cats should be treated for a week or so before delivery with an anti-biotic. I don't recall exactly why but I seem to remember something about it keeping the babies from being infected coming through the birth canal. In your information, you stated that this was not necessary. Can you see any benefit at all to administering anti-biotics (particularly Zithromax) to the Mom ahead of time? If not, why not?

3) If we use the 10-day early vaccination plan, how soon can the next vaccine be administered? Can we vaccinate as early as 5 weeks or should we wait until the 6-week mark?

4) I have every cat and kitten in my cattery on a protocol of l-lysine and interferon and they have been for two weeks. This was the earliest I could get the l-lysine compounded by a phamacist. Is two weeks sufficient to suppress the virus? We have gotten information recently about the l-lysine that it is not effective unless administered BEFORE the onset of the herpes virus. Would there be any benefit to administering it to the newborn kittens up to 10 days (perhaps mixed with KMR). Could there be any danger in doing so?

5) Other precautions I have taken are to have all my carpets cleaned, I have disinfected my hard floors with chlorox and will completely isolate the Mom cat and kittens from all other cats in my cattery. Are there any other precautions I can take? My vet did not feel it make any difference removing shoes going from the main part of the house into the birthing room (kittens will be in box and obviously, Mom has already been exposed to everything in my house). Do you have any feelings on this? I, of course, will be washing hands coming in and out of kitten rooms.

6) I still have two older kittens in which the ocular problem has not cleared up. I used 8 vials of Viroptic drops, tried Vira A and used various anti-biotic eye creams, none of which helped. I just heard from a fellow breeder that Zovirax was quite effective and am just now trying it. Do you know anything about this medication. I do have an appt. on Tuesday with an eye specialist if things haven't cleared up by then.

Again, thank you so much for all the information you have provided.

Answer:

1) Kittens do get protection against herpes virus and calicivirus from the mother through ingestion of colostrum. I didn't meant to say they did not have maternal antibodies. The intranasal vaccine seems to be able to break through this maternal immunity better than the injectable vaccinations, though, allowing it to be used earlier than the injectable vaccines. Remember to use a vaccine that does not contain panleukopenia virus if you use an early vaccination protocol!

The maternal immunity is variable among kittens but should have worn off by about twelve weeks of age in almost all kittens. Unfortunately, many kittens become exposed to viral strains that are more potent than the vaccination strains and these "wild viruses" break through the maternal antibody protection before the kitten can be protected, if only injectable vaccines are used and sometimes even when both intranasal and injectable vaccines are used. Using vaccination at a very young age, as soon as the intranasal vaccine is likely to work, the hope is that the vaccine will establish protection in the local tissues the virus must establish itself in, before the kitten is exposed to a potent viral strain.

2) I have seen information, from someone who signs their name as "Dr. David Richardson" on the internet about the use of azithromycin (Zithromax Rx) on the 58th day of pregnancy to try to eliminate chlamydiosis in pregnant cats. The implication in the material is that chlamydiosis is a major problem among cattery cats but the evidence for viral pathogens as the major cause of upper respiratory problems is much greater. In general I try to avoid the use of antibiotics during pregnancy on the premise that any side effects that affect the mother could potentially be bad for the kittens, as well as worry over direct effect on kittens. However, I have no evidence to suggest that there are problems from the use of azithromycin in this manner -- I just don't know one way or the other.

3) I don't see much point in vaccination using injectable vaccines prior to eight weeks of age, IF intranasal vaccine is used earlier, because maternal immunity starts to fall into the range where these vaccines are likely to work at that age. However, there is no reason that kittens can not be vaccinated as early as five or six weeks of age and then every three to four weeks until they are over twelve weeks of age. There is a potential risk for causing cerebellar problems if a modified live vaccine containing panleukopenia virus is given prior to four weeks of age.

4) L-lysine works by interfering with virus replication (reproduction). It is used in chronically infected cats to try to suppress intermittent clinical signs by preventing the virus from suddenly ramping up replication successfully when the cat is stressed enough for its immune system to be functioning poorly. So in a sense, the information about using l-lysine prior to an infection is correct, except that it is new outbreaks of signs in cats who are chronically infected. I suppose that l-lysine might be useful in preventing a new infection with herpes virus, due to the same mechanism of action but I don't know of any research on this. I have no reason to suspect problems with supplementing l-lysine in young kittens but I also have absolutely no information that suggests it is safe. It does usually take a month or so of administration in chronically ill cats to see much effect.

5) I suspect that your vet is right that changing your shoes would only offer a miniscule difference in protection against spread of the spread of herpes or calicivirus. But having been a large animal vet once, and having changed boots lots of times when going from farm to farm, part of me still thinks it is a good idea.

6) In a study done by Dr. Nasisse, et al. (1989), the order of effectiveness listed for antiviral drugs was 1) trifluridine (Viroptic Rx) 2) idoxuridine 3) vidarabine (Vira-A Rx) 4) bromovinyldeoxyuridine 5) acyclovir (Zovirax Rx). Dr. Nasisse is one of the more active herpes virus researchers but primarily is concerned with ophthalmologic effects, so there may be some differences if systemic effects were considered. Some people are using famciclovir (Famvir Rx) for herpes virus in cats now, but there isn't much information on safety or efficacy of this medication, at least that I can find. Valacyclovir (Valtrex) is considered to be pretty toxic to cats, so there are some antiviral agents that are not safe.

I hope that this helps some.

Mike Richards, DVM 1/31/2001

Herpes virus (rhinotracheitis virus) and persistent ear infections

Question: Dear Dr. Richards:

I have a small "haven" for cats that is the result of moving to the country and experiencing the thoughtless acts of people depositing their unwanted cats and kittens on my lawn. My mom is an animal lover and instilled in me the love I have for animals along with taking responsibility for them. (In the last 3-4 years I have had upwards of 30 cats spayed and neutered.

We have a special cat room set up, heated and immaculate that houses about 20 cats. Here is my problem. They are all innoculated and tested for the cat diseases. None have tested positive for leukemia that are in the room. I've read some of the e-mails sent to you on the topic of the herpes/rhino virus and am wondering if that is what I have. Many of the antibiotics mentioned have been tried. Baytril seems to be the best and I found the interferon to help after the meds stop (but now my vet is having trouble getting it at a reasonable cost) But lately the cats have gotten some inner ear complications (additional Prednisone treatment) that if I don't notice a change in their behaviour immediately, progresses quickly to total incapacitation (can't do more than lift their heads up). I've lost 2 after discovery despite aggressive treatment at the vets. The others end up with a head tilt.

It's the same scenario as some of your other subcribers....stop the antibiotics and the upper respiratory returns. The younger ones seem to be more susceptible, and some of the older ones have no symptoms at all. What is happening when it goes from eyes and nose to the ear? Does the virus attack the central nervous system, or is there a bacteria that's involved? It affects the cats differently. I've noticed the cats that have the cough, don't end up with the ear thing. Is herpes/rhino spread through shared feed and water dishes ?(the cats I've isolated don't seem to have the re-occurring problem.)

When the ears are examined, some have tumor-like growths deep inside that don't go away. One has one that you can see with your eye - Gentocin Otic seems to reduce it, but it never goes away and has a tendency to get gooey.

I put alot of time (and money) into nursing these cats back to health, but I am getting frustrated because it feels like a losing battle sometimes (not all the time, there have been happy endings too.)

I would deeply appreciate any information or help you can give me with this.

Sincerely, Christina

(who is going back to school this fall to be a licensed vet tech so I can be a better cat nurse!)

Answer: Christina-

You probably do have a problem with herpes virus (rhinotracheitis virus). It is extremely hard to suppress this virus when there are more than seven to ten cats interacting on a regular basis. The virus is spread primarily by close contact between cats so in a shelter situation a big part of the solution is to keep the individual cats caged so they don't have direct contact. This wouldn't seem to be very practical for your situation, though. Shared water bowls, food bowls and litter pans all contribute to the contact among cats and are probably strong contributing factors in virus transmission. Vaccination doesn't seem to help much among the adult cats in group situations but it is hard to be sure that it isn't limiting some of the damage even when it isn't controlling the problem.

We notice a strong correlation between cats who have persistent sneezing problems and cats with persistent ear infections. Our assumption is that these cats probably have blockages of the eustachian tube or perhaps viral inflammation of the middle ear causing them to have external ear infections. Persistent ear infections in cats often lead to the development of purple lumps in the ears which are usually granulometous (caused by irritation) rather than cancer. We do see some cats with ceruminous gland adenocarcinomas, a tumor that affects the ear canal, but so far I have not made a strong connection between these tumors and herpes virus infections.

Chronic herpes virus infections and calcivirus infections seem to induce nasal polyps in some cats and these have been associated with middle ear/inner ear problems in some cases, presumably due to blockages of the eustachian tube. Sometimes it takes examination under anesthesia to see these polyps in the pharyngeal region (upper rear portion of the oral cavity) or the nasal passages. If there is infection of the inner ear it may be possible to see this on X-rays.

We have the best luck with azithromycin (Zithromax Rx) for secondary bacterial infections from chronic herpes virus infections but other antibiotics have worked on occasion, including enrofloxacin (Baytril Rx) and amoxicillin-clavulanic acid combination (Clavamox Rx). Giving l-lysine, 500mg per day per cat, also seems to help lower the incidence of problems (but not eliminate them). Interferon is reported to help in some instances. Unfortunately, the best way to reduce the incidence of recurrences is to limit the contact among the cats, which may be difficult for you in your circumstances.

We have not tried the intranasal vaccines for herpes virus and calicivirus but some vets feel these help, even in older cats who are chronically infected, since these viruses provide better local protection in the oral and nasal tissues where the infection gets its first foothold.

I wish that I did have something really good to offer you in the way of dealing with this problem. It must take a lot of dedication to provide a private shelter situation as you are doing and I know that this makes it much harder.

Mike Richards, DVM 1/29/2001

Christina,

Congratulations on your new career choice. You're right, the more you know, the better advocate and nurse you are for your cats. I'm sure you'll do fine in your studies and the cats will help in any way they can. They are sooo good at leaving study material alone.

Michal

Herpes virus in Costa Rican Shelter

Question: Dear Dr. Richards,

Our vet has red the article about herpes viruses in cats (especially kittens) He requested to ask you the question What type of antibiotics is most effective to combat this virus in kittens and cats? We have a lot of problems with this virus in our shelter.

Lilian-

There is new information that suggests that transmission of herpes virus in group situations may require closer contact than was previously thought. It can help a great deal in preventing spread of the infection just to keep cats from closely interacting. This is hard with very young kittens but keeping them together in litters or small groups and avoiding contact between groups may help limit the spread of the virus.

Using an intranasal rhinotracheitis (herpes virus) and calicivirus vaccine and innoculating kittens as soon as their eyes open can help to control infections in shelters and group situations.

Limiting spread of the virus through fomites (things like cleaning mops, cleaning cloths, etc) can be helpful --- using paper towels and throwing them out between cages can be very helpful. Dilute chlorine bleach diluted 1 part bleach to 30 parts water is effective at killing the virus and is inexpensive.

Doxycycline is an effective antibiotic that kills the most common secondary invaders, such as Bordetella, chlamydiosis and mycoplasma organisms. Azithromycin ( Zovirax Rx) is also effective against most of the secondary bacterial invaders and can be very helpful in controlling secondary infections. There are a lot of protocols for the use of azithromycin but 5mg/kg once a day for 5 days, then every other day is one of the more conservative approaches.

Upper respiratory infections in shelter situations are really difficult to control in some cases. I hope that some of this information is helpful.

Mike Richards, DVM 11/4/2000

Herpes virus breakout in Cattery

Question: Dr. Richards,

I subscribed to Vetinfo Digest because, I, cat breeder, have had a virus infection permeate my cattery. My vet sent to a state lab, samples of the nasal discharge for testing for Herpes and Chlymidia. It came back positive for only the Herpes. We have a number of breeding females and one male stud. Of the 6 moms, only 3 showed signs of a mild URI. Every litter of kittens 'caught' it, some with just eye infections, some the runny, stuffy nose. We lost 4 of the kittens that were under 3 weeks old. We had the youngest litter, 2 weeks old, just come down with it. Two died, 4 others have URI. My vet is using Heska drops, nasally administered, as well as antibiotics for secondary infections and genticin eye drops.

My questions, regarding this, for you, are in the area of my breeding cats, what to expect now, with some having been sick, etc. I will list them here. (My vet just learned that the nasal Heska drops might save my youngest litter, the 4 that haven't died.

1. What are the latest drugs to treat herpes? 2.How long do the cats stay contagious? They seem to sneeze well after the other symptoms have disappeared. Are they still contagious during this period? 3.Only the kittens tested positive for Herpes. The adults who had it were not tested. Do the healthy ones still carry Herpes? (They have shown no signs of illness) 4. The kittens who have had it and recovered, can they go to their new homes, and do they remain carriers, and as such infect the persons other resident cats? 5.My male, who has had a severe URI, but not tested for Herpes, can he still be used as a stud? 6. Must each of these cats and kittens who have symptoms, be spayed or neutered? (It has been assumed by my vet, that every kitten had it, the females then caught it, and since the kittens tested positive for Herpes, that the adults will also test for Herpes. 7. Should I close my cattery and start all over?

The first litter of kittens that showed evidence of this virus, was several days after their mother returned from a vet hospital where she had been after getting a severe infection, assumed to be a retained placenta and hospitalized for 5 days. Noone else was or has ever been, in 5 years, a victim of any infection. They are all up to date on their vaccines, tested annually for FeLv, etc.

Thank you so much for undertaking all this extensive problem.

Answer: Herpes virus can be a really frustrating problem, especially in a cattery or shelter situation. I don't think that it is necessary to close down and start all over again, though.

The first thing to consider is the high rate of kitten death that you have experienced. I really think that this is unusual for herpes virus alone. Herpes virus does make it possible for secondary bacterial infections to occur and the combination can result in a higher fatality rate. Bordetella bronchiseptica would be a strong consideration with the death rate that you have experienced, especially if coughing is present as a clinical sign. Chlamydiosis and mycoplasma are other common secondary invaders when kittens are infected with herpes virus. Most of the time veterinarians try to avoid using tetracyclines in young kittens due to dental problems that can occur, but this is less likely when doxycycline is used and this group of antibiotics is helpful for all three of these secondary bacterial infections, so it is worth considering.

Cats that are infected with herpes virus are infected for life. The infection rate in cats is estimated to be at least 70% and is probably closer to 90%, though. The virus is shed intermittently, so it is hard to figure out if one particular cat is more responsible for the continuing infections in a group situation. If one cat shows a strong tendency towards intermittent sneezing or repeated infections it might be worth considering separating that cat from the others. There is a chance of virus shedding during any time when clinical signs are present, so the cats probably are shedding virus during most of the time they are actively sneezing.

When there is a persistent problem with herpes virus in a cattery, it can help to use the intranasal vaccinations for rhinotracheitis (herpes virus) and calicivirus. These can be administered at 14 days of age when necessary. Weaning the kittens at four to six weeks of age and separating them from their mother and the rest of the cats can also be helpful. Then continue their vaccinations on a normal schedule until they are twelve weeks of age. They can be reintroduced to the cattery about a week after the last vaccination in the series.

If kittens show clinical signs of herpes virus, it can help to use interferon topically for eye problems and orally to help suppress the herpes virus, using standard dosages (the topical application to the eyes is done using the oral formulation). Antibiotics can be helpful in preventing secondary infections. Since you have had multiple kitten deaths, it may be best to consider using doxycycline but other antibiotics are helpful, if your vet prefers not to use doxycycline in kittens. Topically, tetracycline ointment (hard to find right now), chloramphenicol drops or ointment and erythromycin drops or ointment may be helpful since these work well against chlamydia and mycoplasma organisms. L-lysine is helpful over the long term and you should consider giving this to all the cats (250 to 500mg/day). Topical antiviral agents are helpful if there is severe conjunctivitis or ulcers. The most effective medication is supposed to be 1% trifluridine (Viroptic Rx) but it is also the most irritating. It has to be used every 2 hours for 24 hours and then 4 to 6 times a day. Compounding pharmacies can also make 0.1% idoxuridine, which many vets favor. There is a third antiviral ointment, 3% vidarabine (Vira A Rx), which we have not ever tried. The last two medications have to be administered 5 or 6 times a day, too.

Due to the high prevalence of this virus there is no reason not to let the kittens go to new homes when they are well. There is no reason to stop using your male stud. All of the cats are potential carriers but this is true of most cats, so even though you are experiencing an obvious problem there is no reason to quit breeding based on this disease alone. It is necessary to continue to consider the possibility of other problems. Sometimes it is very helpful to have a complete post-mortem (necropsy) examination done when a kitten dies but this can also be frustrating since it is not uncommon for the necropsy not to show much.

Good luck with this. Your best bet probably does involve early intranasal vaccination of the kittens, an early weaning and separation program and long term use of l-lysine and perhaps interferon in the rest of the cats. I wish there were more to offer for treatment options but we still lack really good treatments for most viral illnesses.

Mike Richards, DVM 11/4/2000