Thank you to the webinar vet for asking me to talk to you today on the management of equine sarcoids. This quote is probably the only useful thing I've ever come across on an online forum, but I had to steal it for this talk as it's quite frankly brilliant. I hope that we can do far better than treating a forest fire with a watering can by using evidence-based medicine, and we're going to discuss some of that today.
There are many hundreds of different options for the treatment of sarcoids, and no one treatment is universally appropriate or successful. Some of the treatments are evidence-based, and some definitely aren't, but overall, the treatment options will depend on the location of the lesion, the temperament of the horse, the type of the lesion, the financial situation, and of course, also the availability of the treatment. Historically, many sarcoids were left alone if they were not causing an issue.
However, it's my experience that they almost universally just get worse. I would always recommend early intervention rather than benign neglect, because small lesions are much easier to manage than huge ones. In a series of 42 periocular lesions that were not treated when first examined, all required treatment at a later stage, and 64% of the lesions had progressed so much that they were untreatable following referral, leading to the euthanasia of the horse.
Broadly, the treatment options are radiotherapy, electro chemotherapy, laser surgical excision, a variety of different topical treatments and intralesional treatments, photodynamic therapy, sharp surgical excision, and cryosurgery, although there are some others that you'll hear about as well. And we're going to discuss these in some detail. This horrendous looking table I'm not going to go through in detail because it is part of the notes that you will have access to as part of this webinar, but it just tries to summarise the reported success rates for various different treatments for you.
Starting with radiotherapy, there's a published success rate of between 75% and 100%, which goes across the traditional low dose rate, iridium wires and seeds, strontium plesiotherapy, HDR brachytherapy, and teletherapy or that using the linear accelerator. In general, radiotherapy works by targeting cells, damaging the DNA and preventing successful mitosis. We know that it's affected by many mechanisms, including apoptosis, autophagy, senescence, and necrosis, and that different tissues have different tolerance to radiation, which is very relevant when you're thinking about where we're likely to be treating, with bone and muscle being much more tolerant than the skin, which is much more tolerant than the cornea and the lens of the eye.
One of the more interesting forms of radiotherapy, at least to me, is HDR brachytherapy. And this is where you have an iridium 192 source which is welded onto a wire. Iridium emits primarily gamma, although some beta, and is a very high dose in this case.
This means high radioactivity can be given in very short treatment times and to put this into perspective, to give 72 grade gives 3 days with the old iridium wires, which is a low dose rate technique, and it takes about 10 seconds with HDR at average source activity. The source is 0.5 centimetre long and the 12 positions within the catheters that you'll see shortly are every 0.5 centimetre.
So a bespoke treatment is possible with careful planning. The radiobiology of HDR is much more similar to external beam radiation using a Lina than it is to LDR brachytherapy, which means it's very hard to compare the different regimes in terms of in terms of dose and fractionation. It requires knowledge of tumour characteristics that we don't have to be able to do calculations of a biologically equivalent dose.
And certainly, although there is a reasonable evidence base that we will discuss, there's a lot more research needed in this area. Just to briefly run through the procedure, we do an auriculopalpal nerve block, topical anaesthesia to the cornea, and local anaesthetic infiltration into the area to be treated. Where it's feasible, we debulk lesions immediately prior to the HDR if they're amenable to try and minimise the dose required during treatment and therefore reduce the risk of side effects.
We carefully mark out the region that we need to treat and mark every 0.7 centimetres to aid cathede displacement. We can also use barium if required to help with lesion localization on the imaging.
Specialised radiation catheters are placed through or immediately underneath the lesion, and these are placed in a very similar manner to a subpalpi lavage. The catheter placement will depend on the location and the extent of the lesion, with those involving both lower and upper lids becoming more complicated to place, and these are some fairly typical types of treatments that we will be performing. We then image the catheters in situ using a CRM which allows the degree of accuracy that we need for the planning process.
And following reconstruction of the lesion and the catheters on our planning system, this is the kind of thing that we'll end up with for a 3 catheter protocol. Looking at catheters from all angles, perpendicular, above the catheters, and looking along the catheters. We can check the dose from any angle and in any plane by scrolling through these images, which means that we can create a really useful and bespoke treatment plan.
You can see here that sometimes catheter placements can get quite complex for large lesions. However, almost anything is treatable as long as you can image the area. During the treatment itself, the horse is in stocks under standing sedation with telemetric ECG monitoring and is closely monitored from the radiation bunker using CCTV.
There is no operator exposure risk and the horse is completely radiation free both between and after treatments. This is a typical view from a treatment room using the cameras, so you can see the head of the horse, the body of the horse. In the centre monitor is an ECG which unfortunately hasn't come out particularly well on this photograph, but we have a very good overview of the horse doing the treatment, and the treatment itself is typically somewhere between 2 and 10 minutes long, so they're not unheld for very long, but obviously we can go in if there's a problem and sort it out.
I promised to try and give you an evidence base, so here it is. We're almost 5 years out now from the first cohort of horses to have this treatment, and in total, 142 cases have had suitable follow-up time. Most of these have been periocular, but we've also treated some on the ear and some lower facial lesions.
And of these, 90% of them completely resolved. 7% of cases failed treatment with progression of disease or recurrence at the treatment site, and 3% of them had stable disease. Three cases had a second treatment which was successful in 2 of them, and it's interesting to note for comparison that several cases treated with low dose rate iridium also required a second treatment to get a full response.
In terms of the response that you expect, this is fairly typical of one of the more extensive lesions that we would treat. This horse presented 3 days after racing in the Grand National with this rather nasty lesion, and on the right, you can see him less than 6 months later, back in full training with an excellent result. By October, he was in the winner's enclosure following his first race back and had already won far more than the cost of the treatment.
So everybody was really happy with this one. To give you a better idea of some of the cosmetic results we expect, especially around the lateral campus in this case, here's a case before treatment and you can see at 5 months after treatment, you've got a really nice response and those eyelid margins are looking really, really good. Then at 2 years it's looking very similar.
This horse is now about 4.5 years out and it basically looks exactly the same as it did at 2 years. So we get a really long term and good response here.
Looking at some of the different lesion types before and after treatment of a typical response from a varicose lesion. And from some of the slightly more simple nodular and fibroblastic lesions, although this one was very, very close to its eye, and you can see the before and after at 3 months. Again, this horse is about 4 years out from treatment, and again looks very, very similar.
He's had a little bit more hair regrowth, but otherwise much the same as in that 3 month picture. Several of the cases had failed various other treatments, the most common of which was intralesional Mitomycin C, as in the horse and the top photos. But we also saw ones like in the bottom photo that had had surgical excision and topical bleomycin.
It's quite interesting just to note the scalding present at admission, which persisted after the lesion had resolved following HDR. We didn't notice any association of previous failed treatments with the chance of success in these cases, but this is something that we might observe if we treat more and more cases that have failed other types of treatment. It's just quite interesting to note the difference in the speed of response.
So this is a typical mixed sarcoid. You can see at 5 months, both the nodular and the fibroblastic lesions on this horse's lower lid have completely resolved, and that varicose lesion is still progressively improving, but at 5 months still hasn't totally resolved. This horse did go on to have a complete response to treatment, but it's just quite interesting to see how long some of these lesions will take to respond completely.
So it's very easy to sit here and talk about how wonderful the results are, but of course there are risks with the procedure and some side effects are inevitable. We didn't see anything serious, but some of the side effects that we did see were mild to moderate eyelid swelling, generally in 24 to 48 hours, but in some cases, several weeks later. A few cases developed mild, self-limiting moist discrimation.
Almost every case developed some combination of depigmentation, alopecia, and leukattritia. And in a handful of cases, at about 2 to 3 months after treatment, we would see significant swelling and skin sloughing prior to healing. And this was seen at the slightly higher doses.
Four of the 142 cases developed fibrin in that anterior chamber between the 1st and 2nd treatments, all of which resolve a symptomatic treatment. These were really interesting because they were completely non-painful, and none of those horses have had any long-term sequeling. We haven't seen any long term side effects other than the mild cosmetic defects in any of the horses that we've treated, and they are up to over 4.5 years out now.
But longer term effects could theoretically occur 5 to 10 years after treatment. There's certainly the possibility of late cataract formation, and that's probably the biggest risk. The lens dose was very low on modelling and the chances are certainly remote, but it's important to note that all of the owners of these horses were fully informed and consented to treatment.
And I'll be continuing to follow these cases out for many more years. Looking at strontium plesiotherapy, which is up and running at Cambridge Eine Hospital now, strontium is a beta emitter which is held onto a probe and I applied directly onto the area of interest. It's a very superficial treatment, so it's only suitable for very small lesions or for use following surgical excision, but it can give very high surface doses very quickly and easily around 200 to 250 greys, as it's such a local treatment.
So it should be effective for carefully selected sarcoids, and it's certainly very easy to perform with most horses being able to have this done under sedation or a very short GA depending on the location of the lesion in question. You can draw a very simple grid to aid treatment of an area larger than the surface of the probe, because the probe is only about 1 centimetre in diameter. This is one of the cases that we've treated where we saw a sarcoid, so this is a very small lesion on a horse that of course belongs to a veterinary pathologist.
It was surgically removed and proved to be a sarcoid and had dirty margins as you would expect. This obviously is not a location amenable to many forms of treatment, so we elected to try adjunctive physiotherapy in the hope of reducing the risk of recurrence. This was performed very simply and easily under routine standing sedation, and the horse actually represented to me for another lesion in another location at 18 months following treatment, so I had the opportunity to take this nice close up of his nostril, and as you can see, there's no recurrence there and everything's looking really, really good.
This is another case that we treated. This horse had had multiple different treatments, including laser surgical excision and a variety of different topical treatments, but this sarcoid, which was confirmed via histopathology, just kept growing and kept growing and kept recurring despite what was done. So we cut this back to the level of the skin and perform strontium plesiotherapy 3 fractions over 5 days.
And here it is at 6 months, and again this is now about 2 years out from treatment and has continued to do really, really well with no recurrence. In terms of the evidence base for this, it is quite limited. I published data on 10 sarcoids treated on 8 horses with a follow up of between 4 to 30 months, and all of these resolved.
Since then, I've treated an additional 4 histologically confirmed cases, one of which was unsuccessful, so the overall success rate so far is 93%. I would say that this is not because it's the magic bullet that's going to be really amazing to treat loads of cases. I'd say it's just because I'm very good at picking the ones that are likely to respond.
Careful case selection is vital and it's definitely not suitable for large lesions or deep margins, but it certainly seems to have its place. A quick shout out for electronic brachytherapy. This is essentially a miniature X-ray source which is designed to deliver radiation to skin tumours.
It is limited by the source dimension and the topical application, which leads to quite poor penetration of lesions. There is one report of successful treatment for one sarcoid in one horse, so it's certainly possible, although, obviously, that's not much of a, a data set. It is a very superficial form of radiotherapy, so I'd expect that broadly it's similar to strontium and plesiotherapy in its suitability.
At the moment there's definitely no meaningful data available, but watch this space because there are groups, including my own, starting to work on this technique. Looking at some of the drugs which are more easily accessible, the first I wanted to discuss was Mitomycin C. This is a mitotic inhibitor, which is an anti-tumor antibiotic.
It cross links DNA and inhibits replication. It's used in a variety of different human cancers, and its main side effect is delayed myelosuppression. In terms of the evidence, there's a small case series of periocular sarcoids with a 100% success rate quoted.
This has only ever been published, to my knowledge in abstract form, and it's interesting to note that we've treated multiple cases with HDR that have recurred or not responded to mitomycin C, so I would certainly question that 100% success rate. However, again, it has its place. It's fairly simple to do.
You create a 0.04% solution and you deliver it as between 0.5 and 1 mL per cubic centimetre of tumour.
This is repeated every eight weeks until clinical resolution, which usually takes 3 to 4 injections. Briefly, just to discuss the technique, which is the same for any interlegional protocol, and we'll talk a little bit more about this, but it's a cross hatch technique because you want to give the prescribed volume into as wide an area as possible. So you pre-place 18 gauge, 1.5 inch needles parallel at 1 centimetre intervals in all planes.
It's much easier if you do this under local anaesthetic. And then you inject the drug into the lesion whilst withdrawing the needles, aiming to infiltrate as wide an area as possible. It's important to take sensible chemotherapy precautions, and you should really be wearing gloves, mask, goggles, and gown, and using a Loer lock syringe when doing this.
It's not a completely benign process, and it should certainly be reserved for lesions where there is a tumour bolt to inject into to avoid significant skin sloughing such as that seen here. This horse did really well in the end, and that sarcoid didn't recur, but it's rather a dramatic response and probably it could have been treated in a different way without causing so much damage to the surrounding skin. Just another weird thing you can occasionally see is this alopecia and white hair formation tracking away from the area of injection at the medial campus of this horse.
This is presumably some sort of lymphatic drainage from the area, but owners can get quite upset about it, so it's worth warning of the possibility because it does occur from time to time, and there doesn't seem to be any rhyme or reason which horses get this and which don't. Moving on to electro chemotherapy, this is where you expose the cell to a strong electric field, increasing the transmembrane voltage and the permeability of the cell membrane. It's a method of delivering non-permanent cytotoxic drugs such as bleomycin, or low permeent drugs such as cisplatin to the tumour.
You then apply an electric pulse to increase penetration into the cell. It can be used as a sole treatment or in combination with laser resection. And there's a reported success rate of over 90% with careful case selection, so it certainly seems to be very useful.
The main downside is it requires multiple general anaesthetics, which increases both the cost and the risks of providing treatment compared to the majority of other options. However, when you've got difficult lesions, this is certainly a really interesting way to approach them. Laser surgical excision is growing in popularity.
Most commonly, it's a diode laser, but there is also carbon dioxide lasers in clinical use. Laser surgical excision is generally quite simple to perform, and it's suitable in the majority of locations, especially where lesions are early and well circumscribed. The reported success rates are between 62 and 83%.
It seems to be less useful for periocular lesions, although exact data have not been reported. And certainly the recurrence rate seems to be higher for varicose lesions and those on the head and neck. It's important to note that where recurrence occurs, it can be very aggressive in nature, and the main thing that's going to influence that is whether you're able to get good margins of treatment.
In areas where good margins are not gonna be possible, I would avoid laser surgical excision and look to use something else. Thinking about some of the topical treatments, AW 5 cream is probably the most commonly used. It's only available through Derek Nottenveldt's online referral service, and it's some sort of combination of fluorouracil, fire uracil, heavy metal salts, and steroids, although the exact composition remains a closely guarded secret, which is quite interesting in this day and age.
Even in my time as a vet there have been several different formulations, AW 34, and now 5, and there's little data on any formulation, despite many thousands of cases that have been treated at this point. To my knowledge, there's no specific data on AW 5 despite its wide use. But AW4 data suggests a success rate of around 70%, except periocular lesions where success rates are as low as 35%.
It's important to note that there are high morbidity rates, you should expect some degree of pain during the initial and later healing processes and warn the owners that a wide slough occasionally is seen, such as in this poor donkey. It's also really important to make sure that you only ever use this under Derek guidance, and this is a case where AW-5 was placed without his guidance. It was left over from somebody else's horse.
It's a horrible lesion over the stifle of a young event horse, treated with the topical cream, and this is what resulted. So this would never have happened under Derek's guidance. Really, really important to make sure you involve him in all of these cases.
Looking at 5 fluorouracil on its own, it's a chemotherapeutic compound which is an anti-metabolite. An anti-metabolite is a compound similar in structure to naturally occurring metabolites that are required for the viability and division of cells. The cytotoxicity of this substance leads to DNA damage and cell death, and it's widely used in a variety of human cancers.
It is myelosuppressive and causes mucositis, but its side effects topically are relatively minor. It's a major ingredient in AW creams and as I've already mentioned, it's available as a sole ingredient called Epidex through human pharmacies, which makes it very accessible. It's been reported to have a 67% success rate for selected lesions, generally superficial varicose and occult lesions, and this is usually given twice a day for 5 to 10 days.
You can combine it with tazarine which we'll discuss next. Broadly, I would expect similar local reactions to those seen with AW creams in terms of some swelling, some soreness and some sloughing, but it's certainly not as dramatic as the AW cream, probably because it doesn't penetrate quite as well. Interesting to note that 5FU is widely used for superficial skin tumours in humans as well, and it has got a really good evidence base.
Just a quick mention about tazarine, it's a retinoid cream that can be useful to reduce the amount of crust in thick varicose lesions. It's not a primary sarcoid treatment, but it certainly has its uses because it increases the chance of penetration of other topical treatments in cases such as this. Emiromod is an immunological modifier and is anti-proliferative with antiviral and anti-oplastic properties.
It stimulates the innate immunity and is licenced for basal cell carcinoma treatment in humans. There's a reported success rate of between 60 and 72% for superficial lesions, but it's really important to expect a wide local reaction and soreness, such as this poor horse here. What's quite interesting to note is that this treatment was given on the lower eyelid of this horse, and you can see the soreness has spread via a kissing lesion effectively onto the upper eyelid as well.
It can take up to 32 weeks or 3 times a week treatment, which can be really hard to complete due to pain, and that's really its main disadvantage, but it certainly has its place with some of these periocular lesions in particular, if it's carefully applied. Acyclovir is an interesting one. It's antiviral and interferes with DNA polymerases, and this means that its method of action in sarcoids is really unclear.
The BPV virus, assumed to be associated with sarcoids, doesn't have thymodine kinase, which is absolutely required for its method of action. But acyclovir may have a minor bystander effect on suicide genes and cells, which perhaps is why it seems to be effective in some lesions. It's certainly quite controversial, and in the literature there are success rates reported for early superficial lesions of between 53 and 68%.
However, it's also been associated with possible treatment failures in sarcoid cases and has been shown to have little or no benefit in another study, so it's quite hard to know where it sits. However, it is very simple and cheap, and its owner replied, and it doesn't cause any pain. So it's certainly an option for some of the very early occult lesions.
Blood reat ointment is another interesting substance. It's an extract of a plant that I'm not even going to attempt to say that has cytotoxic and immune modifying effects due to the alkaloids present. The only thing I could find in the literature on this is an owner-based survey where owners considered it had a 58% success rate.
There doesn't seem to be any published veterinary data, so it makes it a little bit hard to make definitive recommendations, especially because the horses treated in the owner survey were treated for between 1 and greater than 42 days. So really no idea on an appropriate treatment length or how to do it. It's certainly cheap and cheerful, but it can be painful and can cause Scar formation with associated swelling and discomfort.
It could, however, be useful for small lesions where there's budget considerations. Bleomycin's quite an interesting one. It's this non-permanent cytotoxic drug that we mentioned already.
It induces DNA stand breaks and is another anti-tumor antibiotic. Again, used frequently in humans, and side effects of IV use include pulmonary fibrosis and flu-like symptoms. There's certainly a very good rationale to use it with electro chemotherapy or as an intralesional injection.
It's interesting to note that in human tumours, it's not used topically. But it is used topically for dysplastic oral change. It's been described for use in periocular lesions in combination with either 5FU tazarine or lignaccaine creams.
The success rate for the current protocol that's recommended, which is a bleomycin linocaine combination, hasn't been reported yet, to my knowledge, and it certainly is an expensive and quite intensive protocol. Horses can get sore and may resent treatment. I've already mentioned this case with some scalding below its eye and also on the right hand side you can see another case, and you can imagine that this horse is quite sore at this stage.
It may be more effective when it's combined with other agents, and there is some data in the literature looking at bleomycin plus tazarin compared to bleomycin plus 5FU, where the combined effects were more effective than either treatment alone. This is probably due to improved penetration of bleomycin into the cells following disruption of the epidermis. Moving on to some of the intralesionals, starting off with cisplatin, which has been quite well described.
This is platinum-based chemotherapy, which cross links DNA and leads to cell death. It has a massive variety of uses within human cancer treatment, and nephrotoxicity is a big concern along with neurotoxicity and other typical chemotherapy side effects. It's also associated with secondary cancers such as leukaemia, and there are certainly significant health and safety concerns with handling this substance.
So if you're going to use it, please be careful. It's actually quite difficult to achieve accurate injection in clinical cases, and the success rate in periocular lesions is down at around 33%. Within the literature body, it seems to have a success rate of between 53% and 96% in other areas.
It's quite unclear why there would be such a massive variation, but it's probably down to careful case selection. In a recent study, it seemed to be associated with treatment failures. So that's another caveat with its use.
It's important to note that when you're doing intralesion injections of cisplatin or any of the other substances, you're likely to get spillage. So please use appropriate health and safety precautions and ensure that the owner is fully informed of the risks. Broadly looking at a protocol, what's been described as dissolving 10 milligrammes of cisplatin in a ml of water for injection, adding 1.8 mLs of medical grade sesame oil, and 0.2 mLs of span 80 to make a stable emulsion.
You can then use a 3-way syringe and a 3 syringe 3-way tap technique to create a stable emulsion and leave that for 3 minutes to ensure that this emulsion is very stable, and this will give you 3.3 milligrammes of cispain per mL. You inject this into the lesion, and it's really hard to give guidance on how much is required.
Generally, the recommendation is to flood the tumour as best as you can. And this is just a diagram which is stolen from the textbook of clinical equine oncology. It just gives a nice idea of how to do the mixing and also how to do this crosshatch technique that we've already discussed.
It's very simple to describe this, but it's certainly a lot less simple to do. Most of these lesions are actually quite difficult to inject because they're made of such dense tissue. It's interesting to note that cisplatin failures are certainly cropping up, and this is a typical case that I've been involved with.
So before the cisplatin treatment and after cisplatin treatment, you can see that the sarcoids obviously progressed quite a lot, and it hasn't unfortunately achieved anything. So this would be certainly a case where other treatments would need to be pursued. There are various other intralesionals described.
In terms of the published data, a small number of cases have been described having had intralesional 5 FU, which suggested success rates of 62%. Although the protocol is very vague and it's hard to give specific recommendations on this, but it certainly could be useful for selected cases. Carboplatin is being used with increasing frequency, but again, there doesn't appear to be much or any published data, and did so for intralesional bleomycin.
One classic intralesional is intralesional BCG, which is certainly the most common form of immunotherapy for sarcoids and horses. It leads to an intense immunological response due to local injection of protein cell wall extracts of BCG. There's no direct effect on tumour cells, and it relies on the immune system recognising the tumour cells as foreign.
It's certainly only suitable for discrete lesions with periocular fibroblastic and clearly defined nodule lesions being the main successful use. It's associated with anaphylaxis, but premedication with IV corticosteroids and flunixin prior to treatment appears to stop this risk. And the general protocol would be to dilute one vial of the BCG in sterile water.
For a very small tumour, you're looking at diluting it in 0.5 mL, and for larger tumours, dilute it into 1 to 1.5 mLs of water.
You want to be injecting this intralesionally using a 1 mL tuberculin syringe or a dental pressure syringe with Loer lock, and a 24 to 26 gauge needle. It's really important to make sure it's only injected intralesionally to reduce the risk of anaphylaxis, and you can repeat this as required, up to 10 injections, around about 7, 1421, and 28 days, and then after that, if it's still not resolved every 4 weeks. The reported success rate for nodular and fibroblastic lesions is between 58 and 69%.
And it's important to note that it's unsuccessful for varicose and occult lesions and it's unsuitable for limb sarcoids where it's actually been reported to make them worse. Occasionally you may lead to an abscess or chronic discharging tract, and this can require surgical debridement, so it's just something to warn the owners about. Intraregional BCG is still quite hard to get hold of, but there's another similar product on the market called immunocydin, which is available under special import.
It's generally used in a very similar way and it has the same sort of success rates. Moving on to briefly discuss photodynamic therapy. With this, you apply a photosensitizer and 4 hours later, apply a specific wavelength of light, which leads to reactive oxygen species formation and necrosis and apoptosis of cells, especially those that are rapidly dividing.
And the inflammatory response may help increase anti-tumor activity. There are hugely variable success rates reported between 14 and 93% success rates, so it's really hard to know what to do with this. In the largest case series, there's only one month of follow up, so it's pretty inadequate data, but likely requires very careful case selection to get those really good case responses.
A lot of the time, it's combined with laser ablation to increase the success rates. And it's important to note that it's time consuming and it's not particularly cheap. It's quite painful and has to be done under sedation, but it certainly seems to be useful for carefully selected cases.
Looking at cryosurgery, another thing with success rates vastly differing between 9 and 66%. Again, this is probably due to case selection. It's certainly very cheap and easy, and it may be suitable in selected early lesions.
Finally, the most simple thing to use would be an illustrator band. This is only suitable for a clearly defined nodular or fibroblastic lesion with a clear margin that you can get underneath. In these circumstances it can be extremely effective and it's certainly very cheap and easy to do.
The caveat really is if you select your cases carefully, you'll be a hero, but if you choose the wrong cases, you'll cause an absolute disaster. So there are a huge amount of options, and these are just some of the most common ones with some evidence behind them. How do you choose?
As I mentioned already, I would be looking at location, budget, convenience, temperament, and the owner's expectations for the case. In terms of specific locations, periocular lesions are probably the most difficult. They're very close to sensitive structures, and they appear to have a propensity towards becoming invasive and extensive.
I have always said the last few years that HDR would be the first choice if the budget allows. At the moment, unfortunately, it's not available, although it is being set up at the University of Cambridge, Cambridge equine Hospital. So it will be available hopefully in the next 12 months or so.
Other options for these really depend on the type of the sarcoid, and I would suggest seeking advice from someone that deals with a lot of these cases in order to make these decisions. Looking at lesions on the lower limb and ear, these are very difficult locations and they're unlikely generally to be amenable to topical treatments. Again, they're very close to sensitive structures, and in general, I would suggest laser excision where it's possible.
And if there is the budget to do it, adjunctive strontium physiotherapy, as we've already mentioned, is really, really useful. However, that's only available currently at Cambridge Equine Hospital, so obviously that limits how useful it can be to a lot of cases. In terms of what do I do, based on the evidence in the literature, HDR once it's available for any lesions around the eye, and as a first line treatment in pretty much any other location, I would use laser resection unless there was a good reason not to.
I'm very happy to be emailed for free advice on how to select a treatment and what to do with specific cases, and my email address is there on the screen. And finally, I would just like to comment that it's really easy to lose sight of why we do what we do. And these are just some of the cases that we've treated with HDR who are all back out doing their job, having a great time.
Enjoy these sarcoid cases, they can be incredibly frustrating, but they can also be very, very rewarding, and I hope to hear from some of you soon. Thank you very much.
