Restarting vaccination

RE: Restarting vaccination

Braden Collins — Fri, 15 Apr 2016 07:32:22 GMT

We have taken the path of charging the same for our vaccines, regardless of the species or type of vaccine. that is, a C3 costs the same as a C5 as a F6.... It has taken the finincial side of the decision away and makes it very easy to tailor the vaccine to the animals requirements. We have done it for around 12 months now, and we are finding the vaccines are still being used in similar proportions. We strongly believe in tailoring the vaccine to the pets requirements, so indoor cats don't get FIV or FeLV, but if they're not committed to keeping them in, we given them the works.

Parvo is definately still around. We would have seen well over 100 cases over the last 5 years at our clinics. There wasn't any for a lot of years locally, herd immunity dropped and it hit hard.

RE: Restarting vaccination

Nhombokisheni — Thu, 14 Apr 2016 15:29:25 GMT

Very technical and interesting. You have just given us a good review of the subject right there!!!!!!

p45 is the nonglycosylated form of the envelope glycoprotein gp70 of FeLV. It therefore encodes for the envelope protein. The following paper does give some useful info about p45 (http://www.google.co.uk/url?sa=t&source=web&cd=2&rct=j&q=p45%20and%20gp70%20for%20felv&ved=0ahUKEwity4yYm47MAhXEORQKHZX4B90QFggoMAE&url=http%3A%2F%2Fwww.ema.europa.eu%2Fdocs%2Fen_GB%2Fdocument_library%2FEPAR_-_Scientific_Discussion%2Fveterinary%2F000144%2FWC500063497.pdf&usg=AFQjCNEgeUAQchV2KmKqAZJ6btWVmZrTNQ) As I have already said licencing takes care of whether a vaccine is good enough or not, in fact manufacturers have to meet the requirements of EU Directive 2001/81/EC as amended.

On the issue of efficacy you can look at these two studies:http://www.google.co.uk/url?sa=t&source=web&cd=9&ved=0ahUKEwjmxJikoI7MAhXFQBoKHS3QCeEQFghBMAg&url=http%3A%2F%2Fweb.mnstate.edu%2Fstockram%2Fsdarticle.pdf%2520feline%2520leukemia.pdf&usg=AFQjCNG7QoxyUrdOls65aZhETkJDJhN-kw and

http://www.google.co.uk/url?sa=t&source=web&cd=4&ved=0ahUKEwjmxJikoI7MAhXFQBoKHS3QCeEQFggqMAM&url=http%3A%2F%2Fwww.pfizerpro.com.co%2Fsites%2Fg%2Ffiles%2Fg10013506%2Ff%2Fpublicaciones%2F2014_32_22_Efficacy%2520of%2520an%2520inactivated%2520FeLV%2520vaccine%2520compared%2520to%2520a%2520recombinant%2520FeLV%2520vaccine%2520in%2520minimum%2520age%2520cats%2520following%2520virulent.pdf&usg=AFQjCNFOYMskA5pjzNyEdctV41hYKa8acA

While the papers look and read good, according tohttp://www.google.co.uk/url?sa=t&source=web&cd=1&rct=j&q=felv%20vaccines%20efficacy%20compared%20pdf&ved=0ahUKEwjmxJikoI7MAhXFQBoKHS3QCeEQFggfMAA&url=http%3A%2F%2Feprints.gla.ac.uk%2F100617%2F7%2F100617.pdf&usg=AFQjCNHry__k-cySE4q_C0r8bptq06AIHQ some interesting observations are advanced. Most importantly that efficacy studies completely ignore the basis of vaccine manufacture.....that is cross reactivity. By varying the vaccinal antigens, it means each vaccine performs based on how homologous the challenge virus is with the vaccine antigen components.....i.e. if you use vaccine with antigens C, D, E which cross react to cover P, T, G, B , and then challenge with virus strain C the response will be very high, yet the same vaccine challenged with strain G (heterologous) will give a poorer response. Hope this is making sense.

It's like getting two burgers....one from Burger King and the other from McDonald's ....I sure which one will elicit the more positive reaction although both can sort my hunger.......honestly I am poor at giving examples please pardon!!!!!!

So I say again these registered vaccines have met the minimum requirements and provide cover. One of the papers brings in a dimension of intercurrent disease which is vital because cats are notorious for going around as if all is well when it's far from that.

I honestly believe subsequent vaccines provide cover regardless of brand, and the choice of how frequent you do it can be influenced by disease challenge risk...yes. At the end of the day you want to know you did the right thing.....after all vaccines may suppress clinical disease but new research tools are showing that the subcinical picture has its own story to tell.

RE: Restarting vaccination

John Flynn — Wed, 13 Apr 2016 23:33:02 GMT

[quote user="Nhombokisheni"]Hope this helps.[/quote]

Thanks, that is helpful (ditto to the other reply earlier).

So to spell out what I think I know about FeLV vaccines and check there's no big gaps:

Fevaxyn (Zoetis) is an inactivated (whole-virus) feline leukaemia virus, strain 61E (adjuvanted). A course of 2 injections 3-4 weeks apart is recommended. Booster vaccinations are recommended at intervals of 1 to 3 years dependent on risk.

Fel-O-Vax (Boerhinger-Ingelheim) is a killed (whole-virus) FeLV virus vaccine (different strain to Fevaxyn, adjuvanted). A course of 2 injections 3-4 weeks apart is recommended. Booster vaccinations are recommended at intervals of 1 to 3 years dependent on risk.

Merial PureVax is a recombinant Canarypox virus vaccine (vCP97). This vaccine strain is a recombinant canarypox virus expressing the env and gag genes of FeLV-A. Under field conditions, only sub-group A is infective and immunisation against sub-group A provides full protection against A, B and C. After inoculation, the virus expresses the protective proteins, but does not replicate in the cat. A course of 2 injections 3-5 weeks apart is recommended to induce cellular immunity which whould cross-protect with sub-groups B&C. Booster vaccinations are recommended at intervals of 1 to 3 years dependent on risk.

Leucogen/Nobivac (Virbac) is a recombinant purified p45 FeLV-envelope antigen vaccine (adjuvanted). A course of 2 injections 3-4 weeks apart is recommended. Booster vaccinations are recommended annually.

Leukocell 2 (Zoetis) is a mixed subunit vaccine containing inactivated sub-unit antigens (gp 70 and FOCMA) of feline leukaemia virus (FeLV) sub-types A, B and C. A course of 2 injections 3-4 weeks apart is recommended. Booster vaccinations are recommended annually.

Versifel (Zoetis) is another mixed subunit vaccine similar to Leukocell 2 (Zoetis) I think, though I am not clear whether the immunologic component differs or not.

The whole-virus (killed) and recombinant Canarypox vaccines probably afford better immunity than the ones based on isolated or restricted antigens.

I think p45 is supposedly the specific fraction of the envelope glycoprotein gp70 involved in the immune process, in which case I can see how a booster vaccine subsequent to a primary course of one of these vaccines could "boost" the cellular immunity memory no matter which vaccine was given.

The only one then I'm not 100% clear on then is the PureVax (Merial) Canarypox recombinant vaccine with the env and gag genes - I'm guessing that the env genes encode for envelope proteins to include the gp70/p45 thus allowing these isolated vaccines to "boost" the cellular immunity to this specific antigen when administered to a cat recieving a primary course of PureVax, but I couldn't easily find information to confirm this as fact.

So, in conclusion, it is generally advisable to give 2 injections of the same vaccine if the patient has not previously had a course of 2 injections of any FeLV vaccine. However, to boost this immunity at a desired interval, a single injection of any of the vaccines would be acceptable (with the caveat that the whole-virus or Canarypox vaccines are likely to outperform the limited antigen ones and a single injection of one of these to "boost" a previous primary course of a subunit one may not provide as good immunity as if the primary course had been with a whole-virus or Canarypox vaccine; this may be justification for giving a primary course with one of the more effective vaccines at a year of age if presented for a booster for a cat having recevied initial kitten vaccines with less effective vaccine and now being resident in area of greater disease challenge).

RE: Restarting vaccination

Nhombokisheni — Wed, 13 Apr 2016 16:32:10 GMT

[quote user="John Flynn"]

I must say I'm still confused on FeLV vaccines - I know I could read all the guidelines and probably find the answer, but if anyone could just quickly summarize for me I'd appreciate the effort.

Given that most of these vaccines are based on different antigens, if I use a specific brand of vaccine (Merial) and a cat comes to me that has previously had vaccinations with a different type of FeLV vaccine, am I correct to assume that it would need 2 injections of my brand of vaccine given that I don't carry all the various other brands?

Cheers!

[/quote]

Hi. This is a question we had to deal with back in the day when zim economy went downhill and getting the same brand quickly became a luxury.

The thing is vaccines are essentially selected antigens.....and the selection is based on cross reactivity. So while viruses have many variants, the vaccine is made up of those components/variants whose cross reactivity covers the other variants. Based on this, two brands marketed for the U.K. market may have different antigens, however the cross reactivity spectra is not any significantly different.

Manufacturers actually publish these data and use the same to track mutations and variability and only update when significant cross reactivity is lost. This is why some vaccines have not changed in decades.

So to answer your question...... NO you really do not need to start all over again. As far as I know there is no point because part of the licencing process looks at the "efficacy" and I believe vaccines licenced for U.K.all provide adequate cross reactivity despite the use of different antigens.

I believe you can always contact the manufacturers for data if you want to satisfy yourself. It's very much like running out of vibramycin made by one Company A when you just need to give the dog one more shot......and then telling the owner you have to restart the entire course because you only have Monodox made by Company B.

Hope this helps.

RE: Restarting vaccination

Martin Atkinson — Wed, 13 Apr 2016 11:20:26 GMT

[quote user="Anthony Todd"]I'm not sure the mind of the average "Highgate Housewife" has changed that much, let alone your average client.[/quote]I suspect you underestimate the intelligence of the 'average client' Sweeney! With access to Dr Google all except the bottom feeders, who probably don't present for boosters anyway, are more genned up.

RE: Restarting vaccination

Anthony Todd — Tue, 12 Apr 2016 18:49:44 GMT

[quote user="Evelyn Barbour-Hill"]Maybe thirty years ago that was so.[/quote]

A convenient and common reply, and an easy rebuff, but I'm not sure the mind of the average "Highgate Housewife" has changed that much, let alone your average client.

RE: Restarting vaccination

Evelyn Barbour-Hill — Tue, 12 Apr 2016 18:22:47 GMT

[quote user="Anthony Todd"]Without the annual "booster" [sort of like "steroids", without any down side, in most owners' mind] you have no opportunity to influence the health of the animal before you.[/quote]

Maybe thirty years ago that was so.

My clients are all pretty well aware that a vaccine is just a vaccine, they often ask what it's for or whether it's necessary, and they all come for their annual "health check" their "MOT", their "yearly do" or whatever they like to call it.

RE: Restarting vaccination

Rob Davis — Tue, 12 Apr 2016 18:10:01 GMT

[quote user="Gillian Mostyn"] Even an indoor dog (if one existed) could contract disease from a fomite[/quote]

Tangent alert..... I love the word "fomite" - it always reminds me of when at university, one of my fellow students (who is a regular contributer to the forums...) entered the equine theatre in inapproriate attire. The surgeon shouted, "Get out of my theatre, you f**king fomite" - fabulous insult!

RE: Restarting vaccination

Anthony Todd — Tue, 12 Apr 2016 18:03:23 GMT

[quote user="Bob Russell"]Thirty years in practice and not seen my first injection site sarcoma but do accept they can happen.[/quote]

Won't get into a ***sing competition but I would agree.

Nobody has mentioned the "Epivax effect" which is the firm belief that booster vaccination is some sort of medical super-charging effect which prevents ALL known diseases and disease processes in a single, simple injection. Also stops cancer, organ failure and senility.....

The clue is in the name!

Baloney, of course, but the only chance you guys are going to be able to influence [not much] the diet, lifestyle and veterinary management of a beloved pet, which is far more important than the theoretical [and dodgy] belief that boosting immunity to the manufacturer's antigen is a good thing.

Without the annual "booster" [sort of like "steroids", without any down side, in most owners' mind] you have no opportunity to influence the health of the animal before you.

Any science will show it's a load of cobblers, just look carefully at the evidence but take the "booster" opportunity to help the animal in more relevant ways.

RE: Restarting vaccination

Gillian Mostyn — Tue, 12 Apr 2016 16:01:01 GMT

There is no comparison to be made for occasional cats not needing Felv vs routine canine vaccination.

The diseases and modes of transmission are completely different. Even an indoor dog (if one existed) could contract disease from a fomite. The same cannot be said for felv.

RE: Restarting vaccination

Anthony Dennison — Tue, 12 Apr 2016 15:37:49 GMT

Yeah, I found a lot of the 'medicine on a budget' lectures had a pretty big budget!

RE: Restarting vaccination

Martin Atkinson — Tue, 12 Apr 2016 15:31:05 GMT

[quote user="Anthony Dennison"]Was that the one Saturday mid-morning? [/quote]No I went to the corneal trauma lecture as well, it was Sunday morning, medicine on a budget; 'This dog won't stop coughing'. Despite the fact that a PCR screen is hardly low budget the rest was what your namesake (Sweeney) would have approved of - diagnosis as a balance of probabilities and giving therapeutic trials. As a consequence one chronic cougher I have which doesn't appear to have any cardiac/lung or URT pathology and has failed to respond to steroid inhalers has already gone onto long term Doxycycline and Corventral.

RE: Restarting vaccination

Richard Carter — Tue, 12 Apr 2016 14:40:27 GMT

[quote user="Alet Engelbrecht"]Surely clients are bright enough with enough resources to realise nowadays with many vaccines having 3 yearly licences, that their pets are not behind? I truthfully think that amnesties will ultimately harm our profession and make clients trust us less. [/quote]

Absolutely agree - standing in front of a doctor trying to justify the 5th annual vaccine in her cat and having to say 'the data sheet made me do it' is pretty poor.

Absolutely agree that vaccines have put us in the disease free position we are now (in the UK). If you want to see parvo and distemper, you don't have to travel far so yes, vaccines definitely have their place and dropping your guard is an invitation for a disaster. As for FeLV and the cat flu's - definite decrease in incidence and at the end it is about the % in the population that stops the disease, not the individual.

However we also know from WSAVA and personal experience that the general risks of not repeating a vaccine every year are extremely low and that the risk of inducing some sort of vaccine reaction may be higher than the incidence of disease and that reducing to every 3rd year or even longer may be more intelligent and in the patient and client's interests.

So don't try to sell c**p science to your client just because it is convenient or profitable. It will come back in your face. Remember all those politicians who voted for war on the known 'dodgy dossier'??

RE: Restarting vaccination

Anthony Dennison — Tue, 12 Apr 2016 14:32:35 GMT

[quote user="Martin Atkinson"]As a bit of tangent, I went to a talk on chronic respiratory disease in dogs at BSAVA congress and in one survey in the USA a PCR panel revealed the presence of CDV in dogs with chronic coughs at a rate of something like 12%.[/quote]

Was that the one Saturday mid-morning? Almost went, did corneal trauma lecture instead. Was it any good?

RE: Restarting vaccination

Anthony Todd — Tue, 12 Apr 2016 13:47:08 GMT

[quote user="Alet Engelbrecht"]risk/benefit analysis[/quote]

As a very successful vet in Toorak, Melbourne pointed out to me; the "risk", as far as an owner is concerned, is 100% when that owner's animal gets a preventable disease, even if the disease is "very rare" in the general population!.

RE: Restarting vaccination

Alet Engelbrecht — Tue, 12 Apr 2016 12:41:20 GMT

[quote user="Bob Russell"]WSAVA seem to accuse the rabies vaccine of being higher risk. We now have the Purevax cat rabies in the fridge![/quote]

I attended a very good CPD a few years back about the prevention of rabies and the importance of herd immunity. While I agree that the vaccination protocols should be tailored to the individual's risk factors, are we not running the risk of significantly lowering the herd immunity if excluding FeLV from our routine protocol. I would rather say it is an 'optional exclusion' at my practice.

If going back to the OP - in my opinion vaccination amnesty is a big con pushed by the vaccine providers. Surely clients are bright enough with enough resources to realise nowadays with many vaccines having 3 yearly licences, that their pets are not behind? I truthfully think that amnesties will ultimately harm our profession and make clients trust us less. The only positive that it is achieving, is getting patients who haven't been to the vets for more than a year, through the door and the clinical exam may be able to pick up early problems. For that matter a discount may have the same effect and not clogg up consults with needless '2nd vacs' for a month or 2. I am sure the MBA's will have some data about the increased revenue from the 2nd vacs too, but when the MBA in charge of our group suggested an amnesty at our young branch, I fought him on it.

Now for the devil's advocate - are we using the same logic and risk/benefit analysis when offering pre-anaesthetic blood tests? For example the 6 month old coming in for the spay? And before bringing it up, how common are dysplastic kidneys really?

RE: Restarting vaccination

Martin Atkinson — Tue, 12 Apr 2016 12:27:31 GMT

[quote user="George Cooper"]Do you all also "risk analysis" for the other constituents of cat vaccines? I am not certain that I've really seen anything other than the infernal Calici virus associated problems over the last 10 - 20 years.[/quote]There is a risk from live vaccines that are aerosolised or spilled on the cat causing vaccine induced disease in naive kittens so i consider that but as so many kittens are already FHV carriers it would be difficult to distinguish this from latent disease flare-up. I've seen a few cases of post vaccine lameness presumed to be joint inflammation from the FCV component.

[quote user="George Cooper"] Neither distemper nor parvo have been anything like as common as they were, though I have heard of the very occasional case of parvo through the grapevine.[/quote]We saw a case of CPV a couple of months ago - dodgy eastern European import, but in some areas it is still quite prevalent.

As a bit of tangent, I went to a talk on chronic respiratory disease in dogs at BSAVA congress and in one survey in the USA a PCR panel revealed the presence of CDV in dogs with chronic coughs at a rate of something like 12%. There is no reason to believe that it is not also the case here. I also had a chat with Mike Davies, now of Nottingham Uni., and recalled old times when he worked for Fort Dodge and we were seeing CPV vaccine breakdowns. He said back then and again now that we should be looking at failure to achieve adequate immunity against CDV as well as CPV. Make no mistake these diseases are there waiting to make a comeback if we drop our guard.

RE: Restarting vaccination

Bob Russell — Tue, 12 Apr 2016 12:25:56 GMT

Parvo is still around and there is a reservoir of distemper in the wildlife population. Stop vaccinating and cases start to increase.

Dog vaccination is doing a good job keeping the number of clinical cases low. I am under the impression this is why we do it!

There is nothing wrong with building a successful business on the back of protecting patients but vaccination does not mean adequate veterinary care! £15 for a quick booster does not necessarily do much for animal welfare.

RE: Restarting vaccination

George Cooper — Tue, 12 Apr 2016 11:56:36 GMT

Not quite ready to lie down on this one yet!!

Do you all also "risk analysis" for the other constituents of cat vaccines? I am not certain that I've really seen anything other than the infernal Calici virus associated problems over the last 10 - 20 years.

Dog vaccination also appears to have been a successful initiative. Neither distemper nor parvo have been anything like as common as they were, though I have heard of the very occasional case of parvo through the grapevine.

I can recall, way back when, as a schoolboy accompanying the local VS in a mining area of Fife doing a round of visits in some of the mining villages and putting down half a dozen (at least) dogs with distemper. And those were the days of fewer cars, dogs allowed to roam freely during the day and more fractured legs too.

And by way of a PS - many of us have built successful businesses on the back of boosters!

RE: Restarting vaccination

Robin Grimmer — Tue, 12 Apr 2016 11:36:04 GMT

Round here I can't remember the last case of FeLV I saw and FIV is getting rarer. I have however seen several cases of injection site sarcoma which can be just as deadly as FeLV. So in accordance with the WSAVA recommendations, we should tailor vaccines to suit the individual cat. So I don't recommend FeLV vaccination for indoor cats or over 10 years old.

And actually not all cases of FELV are fatal - some cats will become immune, which is why you should always retest a positive 3 months later (unless it has obvious FeLV related disease). It's only when they are persistently viraemic that it is fatal.

RE: Restarting vaccination

Bob Russell — Tue, 12 Apr 2016 11:27:24 GMT

I cannot see any reason why we should not be tailoring vaccinations according to likely risks. If in doubt, protect!

The last soft tissue sarcoma I saw was a mass removed from the chest of a cat. I removed it because it seemed to be growing a bit faster than I was comfortable with. I gave it my 'routine' margins for an unknown mass and was a bit alarmed by the path report when it came back.

Thankfully the cat got away with it! This was the site of a previous cat fight injury so was not injection related.

WSAVA seem to accuse the rabies vaccine of being higher risk. We now have the Purevax cat rabies in the fridge!

RE: Restarting vaccination

Martin Atkinson — Tue, 12 Apr 2016 10:17:01 GMT

[quote user="George Cooper"]It also seems to have been SO much more prevalent in the States than over here. I , like Bob, have never encountered a single case, [/quote]The last time I heard there was a definite link with the multi-valent vaccines they use over the pond which typically also included rabies and FIV which of course we don't.

I have only ever seen one case of VSS and that was in a cat vaccinated by someone else. Histology revealed the presence of aluminium particles in the tumour so that was pretty well confirmed as vaccine induced.

However I have seen a couple of soft tissue sarcomas in cats on the spine which were in sites not traditionally associated with vaccination i.e. caudal lumbar spine so my curve ball of the day is: is the spine of the cat a prediction site for soft tissue sarcomas irrespective of vaccination?

RE: Restarting vaccination

Gillian Mostyn — Mon, 11 Apr 2016 22:25:40 GMT

George - no need to be so aggressive in your reply.

[quote user="George Cooper"]And all of you who do a "risk analysis" - do you also analyse the Houdini nature of in-house cats that wriggle through legs and escape into the big wide world[/quote]

Yes. That is discussed

[quote user="George Cooper"]do you also analyse the 'risk' of owners actually deciding to move home and live somewhere other than your cosy risk free environs[/quote]

Yes, also discussed

[quote user="George Cooper"]do you also analyse the risk of the sheer minimalist "RISK" compared with the fact that FeLV is FATAL, and the any cat might, just might be exposed at some stage[/quote]

Yes, also discussed

[quote user="George Cooper"]And all to save a client fifteen quid or whatever[/quote]

Very rarely a reason for felv not being given. If the cost of vaccination was an issue, the client would be very unlikely to be stood in front of me in the first place. However, your 'fifteen quid' could actually be a lot of money for some people. If they don't need to spend it, why should they?

[quote user="George Cooper"]I'd say stop being so goddamn academic and perhaps live in a real world where cat owners want protection for their cats not some airy fairy "it might get this or that".[/quote]

I disagree. It isn't an academic exercise. I'd estimate that 99% of kittens and 90% of all cats in our practice are vaccinated for felv. There is justification for including it in routine vaccination protocols and if there is any possibility of the cat mixing with others, we would recommend it. However, felv transmission requires prolonged, intimate contact between cats. The virus doesn't survive outside of the body. I allow my clients to have the intelligence to decide if their cat actually requires it.

(I owned a blind, indoor cat for 10 years. He didn't need felv vaccination.)

Oh - and I don't have any reason not to vaccinate other than that it isn't needed. I don't worry about sarcomas - I have only ever seen one. I don't vaccinate for felv in some cats for the same reason I don't vaccinate my children against yellow fever. I only would if they were likely to be exposed.

RE: Restarting vaccination

George Cooper — Mon, 11 Apr 2016 20:36:53 GMT

OK - so there is ONE single side effect that we need to really really worry about - that of a sarcoma developing. This has not to my understanding been linked immutably to the vaccine and there are a number of postulates as to the origin.

It also seems to have been SO much more prevalent in the States than over here. I , like Bob, have never encountered a single case, and I've been using FeLV vaccines since they became available and I managed to rise above what I perceived as the "price objection" - which was in fact a myth.

And all of you who do a "risk analysis" - do you also analyse the Houdini nature of in-house cats that wriggle through legs and escape into the big wide world; do you also analyse the 'risk' of owners actually deciding to move home and live somewhere other than your cosy risk free environs; do you also analyse the risk of the sheer minimalist "RISK" compared with the fact that FeLV is FATAL, and the any cat might, just might be exposed at some stage. And all to save a client fifteen quid or whatever.

Like I said - to the owner whose cat gets the preventable disease it is 100%. I'd say stop being so goddamn academic and perhaps live in a real world where cat owners want protection for their cats not some airy fairy "it might get this or that".

RE: Restarting vaccination

Martin Atkinson — Mon, 11 Apr 2016 16:50:00 GMT

[quote user="John Flynn"]Given that most of these vaccines are based on different antigens,[/quote]Are they? I suspect this is a myth spread by vaccine companies to promote brand loyalty.

[quote user="John Flynn"]...if I use a specific brand of vaccine (Merial) and a cat comes to me that has previously had vaccinations with a different type of FeLV vaccine, am I correct to assume that it would need 2 injections of my brand of vaccine given that I don't carry all the various other brands?[/quote]Well first we have to assume that your first statement is correct which I don't believe it is. But if we do, then if you then vaccinate it twice with your strain what happens to the immunity from the previous strain - presumably immunity against that will eventually lapse and the cat will become susceptible and could die from the previous stain of FeLV? This clearly is a nonsense, a rose is a rose by any other name. I would not mix two different brands of vaccine together at the same time i.e, brand A CHP with brand B FeLV as a diluent but I see no issue with boosting one brand with another at a different time or even different components at the same time but at a different site.