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September 20, 2023

How to correctly vaccinate your livestock with MSD

Mark Ferguson: Welcome back to Head Shepherd. This week we're talking about vaccines. It's a topic that a lot of people are thinking about. Whether they should be vaccinating animals, when they should or how they should. And when things get tough, things like animal health treatments start coming under question. We thought it'd be a great opportunity today to get MSD's Veterinary Technical Advisor in the Lower South Island, Kim Kelly, along to talk us through vaccinology and I'm looking forward to that chat. Welcome Kim. 

Kim Kelly: Great to be here. Thanks for having us on. 

You deal with people asking questions about vaccines and making sure that, if you're going to spend the money, you use them in the most effective way possible. What are the small mistakes that you see being made out there?

First of all, when you say vaccinology, people freak out and think, what on earth is this that we're talking about? And don't worry, I'm not going to go into a lecture on what vaccinology is all about. 

Essentially, farmers are paying for these vaccines and we want them to be able to get their best bang for buck. Often, with slight tweaks in the way you're doing it, you can make sure you're going to get the most bang for your buck. So, you need to use the vaccines and, if you're going to spend X dollars, let's do it well and get the best out of it.

What are the common mistakes that you see made?

Most often, things like the timing isn't right, the dose isn't right or the site of administration might not be in the right place. Even time of year and animals involved - some groups of animals need the vaccines at different times from others. And, if you can get your timing right, then you might end up using less vaccine and save yourself money.

That sounds like a good plan. Often the vaccine fridge is also the beer fridge in the shearing shed. In terms of storing vaccines, are there mistakes that we see happening around that? 

My favourite mistake is when the farmer rings up and says - and this happens every time - the shearers have turned down the fridge in their woolshed to keep the beer cold, which means that they're actually freezing their vaccine. And, while the vaccine does need to be kept cool, it doesn't like being frozen. If you do have frozen vaccine, I'm afraid that is an instant ‘chuck it out’. It is not going to work. But it's always the shearer's fault and it's always about beer.

Everything we're going to talk about today is associated with reading what's on the label. Farmers in general, but generally it's male farmers, do not read labels. If you made a lot of these little mistakes - only giving one shot or doing things wrong with the needles - it's actually written on the label. The first lesson is, if you can, read the label. 

For storage specifically, it's not just how it's stored in your fridge in the woolshed, it's when you then take it up to the paddock or the yards and it might sit in the sun for half a day on the way out there and it is not staying nice and cool. Things like using a chiller bag to transport it from where you buy it to the farm and having it in a chiller bag when you're out in the yards in the sun are really important - in some cases, the vaccine will be destroyed by heat. There's no point spending all your money and all your time vaccinating when the actual vaccine is probably not going to do its job.

Exactly. It seems like a common theme, our like of cold beer and not reading labels. It's quite easy to relate to a few of those things. 

A bit of a stereotype there, I didn't say that was the case, but we do have some farmers who openly tell me they have never read the label within their 25 years of farming.

I think I would probably squeeze into that category - even that couple of hours trip from the shops to the fridge in the shearing shed, the vaccine should still be insulated to protect your investment?

It depends on where you are. If you're somewhere in the country that's a hell of a lot warmer than central Otago in the winter, it's more likely to be a problem than down where it is pretty cold. I do know of someone who put it beside the fridge in the woolshed and it froze because it was that cold outside. It would have been better had it been in a chilly bag, because it wouldn't have gotten as cold. 

Is there any way you can tell that it's either cooked or frozen? Or does it all still look the same? 

Great question. When it's cooked, you would pick it up and it's not cool at all, and in some cases that will be fine. It's worth checking with the manufacturer and working out exactly how long it's been like that. But, if it's frozen, it will often look different in appearance. There'll be ice crystals in there for a start, but it can change the colour of it as well. So, in general, if in doubt, throw it out. Don't use it if you're not sure. You don’t want it to do any harm to your sheep.

You do hear of - and see - the odd lesion on carcasses and those downgrades that go along with that. I guess there's some ‘vaccine disadoption’ from farmers because of that. What can you do to avoid those lesions happening? 

In general, read the label, which we've already talked about. 

Slow down already. Unfortunately, we have conveyors who get paid per animal that gets done.  There's a lot of incentive to get three farms done in one day. And, when you go fast, you are way more likely to cause damage to the animal than if you potter away for the day.

The location of the injection is really important. Pretty much all of the vaccines say to use it in the anterior half of the neck. That's the top half, closest to the sky, and it's right up close behind the back of the ear, not the shoulder. There is no reason to be injecting them as far back as the shoulder.

The animals need to be clean and dry. One of my favourite questions I get is, "My sheep are wet, can I vaccinate them?" And the answer is, “You can, if you change the needle for every animal,” and that usually puts people off and they won't vaccinate wet animals.

Talking of needles, the needle change is really crucial. It'll say, once again on the packet, every 20 to 50 animals (or something like that) change the needles. I'm a realist, and I know people do not do that, but you will get more lesions if you don't change the needle than if you do change the needle.

I know it takes time, but it is worth it and you will get fewer lesions and fewer lumps if the needles are clean and sharp. A popular thing is dipping the needles in meths, which kind of sterilises that needle for the one that you're about to inject, but it doesn't do anything about sharpness.

Storing used needles that have been used for a few hundred sheep in some meths and then using them the next day is not a good idea. My dad did it when we were kids - it's commonplace. Don't do that. 

A lot of the vaccines will say to inject under the skin. That means you really need to tent the skin and inject it into that tent. I've seen plenty of people say they don't need to do that - that they could just use one hand and flick it out with a short needle. They might be able to, but I will almost guarantee some of it isn't going where it needs to and you're more likely to get lumps if that's the case.

Those are pretty much the things for avoiding lumps. 

So you've got more bacteria floating around on wet animals?

Correct. And the same with dirty animals that have recently been dipped. If they've been saturation-dipped with some brown water, you'll notice they're dirty. Every time you're sticking the needle through that, you're at risk of introducing more bacteria and bugs. And that risk is doubled or tripled if they have got a blunt needle as well. The sharper and cleaner your needle is, the less chance you have of dragging these bacteria under the skin and causing abscesses. 

A normal shearing cut, or any other lesion, doesn't often result in an abscess. So is it some sort of combination of the adjuvant and bacteria that cause the lesion?

Often a shearing cut is reasonably clean. The other benefit it has is that it's an open cut. With injection site lesions, you have a tiny hole in the skin and you've dragged a whole lot of rubbish in underneath. And then that hole is closed over and it's a perfect environment to grow bacteria. The combination of the stuff that’s in the vaccine and the bugs in there is not usually a good idea and not good for the sheep. 

I guess that all comes back to speed as well. You see some situations with conveyors going flat out and jabbing flat out, and sometimes that's a summer student who's been handed the vaccinating gun and told to get into it without it really being explained. 

They need to have had training, but a lot of them don't have the training and they don't understand that, if they don't tent the skin, it could be detrimental to the animal. If you don't understand why you should do it a certain way, you probably won't do it. 

If you do have the conveyor come in, just say to the contractor, "Look, I've had some kill sheet lesions that I'm really worried about. Could you be real top-notch with your needles and that kind of thing?" That would be a really good idea.

Talk us through tenting the skin. 

Using the hand opposite to the one you've got the vaccine gun in, pinching with your thumb and forefinger, you will create a little tent. Then you're putting your needle at the bottom of where that tent is. You're just lifting it up and literally injecting under the skin, rather than into the muscle or any of the soft tissue. 

I need to say for health and safety reasons, you need to be careful that you don't stab yourself with the needle. In all cases, with most vaccines, it will say on the packet, once again, what to do if you do inject yourself. But, generally, the tent is a pinch of skin with your fingers and then poking the needle into the bottom of it, so you don't hit your own fingers. 

Another reason to go a bit slower is because you're gonna jam a needle into your thumb otherwise!  

In terms of needle length, are there any recommendations there? (Or is it on the packet?!)

Generally, for sheep, you’d go 18-gauge. With the length, you’ve got anything from a quarter of an inch right through to one inch, but a common option for injecting sheep under the skin would be an 18-gauge, ⅜ inch. If it’s another vaccine that needs to go into the muscle, you might need to go - for a sheep - for an 18-gauge, ½ inch or something like that.  For cattle, you’d go 16-gauge and ½ inch [for under the skin] and up to an inch, if it’s going into muscle. 

With the cost / price squeeze going on, the cost of vaccination is something people's accountants might be looking at and saying, can we get rid of those few dollars out of the budget? But I've seen lots of people lose a lot of good stock with pulpy kidney and lots of different diseases that make the cost of vaccines look pretty much a no-brainer to me. What are your thoughts on how people can justify the cost of vaccination?

As you said, a lot of the diseases that we're protecting against - with the vaccines that cost cents - if they get that disease, they're going to die and you're going to have zero value for an animal. You can probably do some maths and work out that you can protect hundreds of animals with a packet of vaccine that costs less, in most cases, than the value of one animal.

We're a business that's affected by the increase in price like everyone else. Our inputs have gone up, even the plastic that we put the vaccine in has gone up astronomically and then transport etc. We're trying to make sure that you don't make shortcuts and that you still use these products without having to cut that cost out. So I say, carry on vaccinating. 

Some of the vaccines will not only protect against death, they have some production benefits as well. You can do some cost-benefit / return-on-investment stuff on those and, in general, you are always going to find that that's positive. 

What are the economics of the diseases that we vaccinate for? The ones that I see causing the most grief are probably pulpy kidney and campy or toxo. Do we know what those numbers are? 

The thing with those abortion diseases, toxo and campy, is that when a ewe gets those, in most cases, she's all right herself, but she loses one, two, three lambs. We've also got data showing that you can increase the production using those vaccines because you have fewer losses.

But, with the clostridials, you are going to get deaths. The annoying thing about them is it's often deaths when the animals are right about ready to go on the truck. For you, you might get more angry at that, than having 10 ewes abort. But, if you do the maths, both of them are significant. 

If the budget was super tight and you're making a call about which ones in the flock you're going to vaccinate, is there any sensible priority that you can sort out?

For a long time, farmers have thought, "Right, I need to use this vaccine in all my sheep." But we can be a little bit more targeted in some cases. With diseases such as toxo and campy, young animals are, in all cases, going to be more likely to be naive and haven't come across it naturally. If we can get in and give them their vaccinations, we might be able to prioritise them.

Just touching on that, giving a proportion of the animals the sensitiser booster -  the two shots - is going to be better than giving all of them one. We sometimes see people who just do one shot across all their sheep. They've got X amount of dollars to spend. They do one shot and they're doing a half job on everyone. You'd be better off doing a full job on a proportion of your animals rather than a half job on everyone. 

For pregnant stock, we can prioritise pre-lamb treatments based on how many lambs they're going to have. You might use a cheaper vaccine for the ones that have a single and you might prioritise the more expensive products for your multiples.

What they eat is important as well. Certainly for the clostridial vaccines, if you've got some sheep that are going on to rocket fuel - high sugar grasses or crops or lucerne - then they are more susceptible to getting a clostridial disease, like pulpy kidney, than those who are eating boring old ryegrass. 

There are lots of things you can look at across your whole flock. It shouldn't be a one-flock treatment. It can be broken down into several lots. Use the information that you get from scanning and things like that. 

One of the differences we see on either side of the ditch is that, in Australia, we always vaccinated at lamb marking and then a booster at weaning. Here, in New Zealand, a lot of people will give a sensitiser at weaning and then a booster sometime after that. Is either of those any better than the other? 

It depends on what you do pre-lamb in the ewes. Depending on what products you use pre-lamb and the timing of your pre-lamb shot - whether it's two weeks before lambing starts or whether it's a product that could let you go a bit earlier than that - will determine how much protection you're going to get in the lambs on the other side. The thing we don't know is the variability in how each ewe responds, how good she is at mothering and how much milk she has and how much she's fed.

All the products say up to 12 weeks or up to 16 weeks. They don't say 16, they say up to. If you have used a product pre-lamb, the ewe has a single, they drink colostrum quickly, and there are heaps of antibodies in that colostrum, those lambs may be protected right out to weaning and so they'll be fine - they're not going to succumb to pulpy kidney or tetanus or anything. That's the ideal situation.

But, there'll be a proportion of lambs where the mother had triplets. Maybe she wasn't in as good condition, so she didn't have as much colostrum. And the lambs had a little bit of colostrum each, but not really enough. Their protection might run out before tailing. The problem is that the farmer can't walk into the paddock at tailing and say, "Put your hoof up if you're protected right now!"

There's going to be a proportion of those lambs that would definitely need to be vaccinated at tailing to protect against losses. While they're sitting there in front of you at docking or marking or tailing, that's a good chance to put your first shot in. But there are so many variables that all we can do is try and minimise the chances of lambs being completely naive in that fast-growing tailing / weaning / soon-after period.

Some vaccines you see have other minerals mixed in them. Is there a risk that if we give vitamins in some other way, we're getting into toxicity problems?

If farmers ask me one question once, they ask me a thousand times - and it’s why can't you put everything in one shot? And I understand it. It's much more convenient to have lots of things in one injection. They get fewer injection site reactions if they only stick one needle in.

The minerals selenium and B12 are the two big ones. You need to determine whether you need those minerals and if it's an appropriate time of year to be giving them and in an appropriate group of animals. With B12, you won't have a toxicity problem but, with selenium, you could have a toxicity problem. And, if you pick up the packets, they always say do not use this product if you are not sure of your selenium status. Or, do not use this in combination with any other product.

We've just developed a tool called the selenium calculator. We've loaded in all the products that we think people are giving their livestock in this country. There are worm drenches, mineral drenches, pre-lamb mineral drenches and vaccines. We've loaded all those products in so people can put in the weight of their ewes or their lambs and they can choose from drop-down boxes which products they're going to use. Then you look at the bottom and it'll tell you whether you're not using enough selenium, using too much selenium (which can be fatal) or you're in the optimal green range. 

It's a traffic light system that will be handy for helping you out with that toxicity. But, once again, you need to give enough. For selenium, New Zealand's pretty deficient and Australia around the coast is pretty deficient too. Using products that have minerals in them might be a convenient way to fix that problem. 

There are a lot of different vaccines on the market. One thing farmers suffer from is getting overwhelmed by so many product options. How do farmers work out which are the priority ones?

Have a really good animal health advisor who knows your farm, your system, your stock. Get them to help you design a plan - I love animal health plans. It's a calendar of what you need to do across the whole year, which animals you need to target and things like that.

The first step is getting an advisor on board - or you can do it yourself instead - Google is an amazing thing. You can do your own research and look at the products and see why one might be better for you.

We're hot on evidence-based medicine. You need to look at the trial data and, if it's New Zealand or Australian trial data, that's even better, to show how well those products work on animals in general. I don't believe some of the shiny brochures. I want to see the trial data behind that and what's backing that up.

“You get what you pay for,” is an adage that fits in here as well. 

If you have an advisor, they'll be able to help you pick between the products and decide what should be the most applicable for your farm. 

If a farmer has a problem with one of the vaccines, is it your role to investigate what's going on?

It’s pretty rare, but if a farmer has used one of our products and feels that it either hasn't provided the protection he or she expected or there's been something adverse happen (e.g. some lumps they’re not happy with), then they should contact the person who sold them the product and then those people will contact us. 

Then it's a huge process for us to enter all that information. We can't just go "There, there, that's a shame, oh well." We've got 12 hours to log it into our New Zealand system and then it will go to MSD Global, and then it will come back to the ACVM or APVMA in Australia. There are strict timeframes. 

We'll look at data such as the date and the batch number, whether we've had any other issues with the product and we'll look for a cause or something that's gone on. But I've been around a wee while and it is rare that we say, “This product didn't do what it should have.”

In general, there's something else going on and you can figure out what's happened and why it hasn't performed as expected. But we want farmers to contact the person that they bought it from and we'll get an investigation underway for them. 

Where can people find the selenium tool you mentioned?

It will be sitting on our sheep facts website: There will be a tab that says ‘Selenium Calculator’*. We'll have to keep that up to date. If your drench isn't on there, it doesn't have any selenium in it at the moment. We've loaded quite a lot on there. If you have any questions, call us and we can try and help you with that. 

Well, thanks very much for your time, Kim. We appreciate you sharing your knowledge on vaccines and I'm sure people will get a lot out of that. 

Click the following YouTube link to watch the correct application:


Dr Mark Ferguson
Article by:
Dr Mark Ferguson

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