If there’s one thing that can make a vet cringe, it’s not blood, guts or abscesses. It’s the misunderstanding and confusion surrounding antibiotics. Antibiotics are one of the most common prescriptions we make, with the average vet prescribing 2-3 courses every day. But what are antibiotics, and how do they work?
Dr Pete Wedderburn BVM&S CertVR MRCVSDr
- May 10, 2018
The increasing threat of antibiotic resistance is one of the biggest challenges to human health in the 21st century. Previously curable infectious diseases are becoming untreatable, with the risk of widespread morbidity and mortality. Resistant infections could potentially spread throughout the world in a short space of time, thanks to the recent growth in international trade and travel.
In Part 1, we looked at how bacteria become resistant to antibiotics, and how without these drugs, modern medicine (surgery, chemotherapy, organ transplantation) would be almost impossible. In this second part, we’ll look at what drives resistance in the real world, and how we can help.
You’ve almost certainly heard of “antibiotic resistance”, or “antimicrobial resistance”, or “superbugs”. But do you know what they are? Or why they’re a problem? Or why we’re worrying about them in animals? Read on to find out more!
Dr Pete Wedderburn BVM&S CertVR MRCVSDr
- May 19, 2016
Antibiotic resistance, like global warming, is a threat to our future that keeps popping up in the media. The topic moved centre-stage today, with the long awaited publication of a major report that specifies the severity of the risk, and the measures that need to be taken to avert the threat.
It's a long report, at 84 pages, and it's worth reading for those with a serious interest in the subject, but here's the gist of what's being said.
This is the time of year when people start to look at their cute little foals, and suddenly realise they're starting to grow up fast... As a result, it’s also when we start to get phone calls from people to talk about gelding them.
If you are considering getting a colt gelded ("cut"), my advice would be to contact your vet, who will be able to advise you on the best approach in your particlar circumstances. However, I'm going to try and go through some of the commoner questions below, so you've got some basic information on the decisions to be made, the procedure, and what you'll need to consider.
The first question, of course, is whether or not to get him cut. It’s an important decision, so these are my thoughts...
The majority of male horses are castrated, and for very good reason - very few people have the facilities, the time, or the inclination to manage an entire stallion. The old adage had it absolutely right - "You can tell a gelding, you can ask a mare, but you discuss the matter with a stallion". Although there are some superbly well mannered stallions out there, it takes years of expert training - and in my experience they're almost always more "bolshie" than a gelding, and much less forgiving of any mistakes. They are also much more easily distracted (e.g. by a passing mare), and prone to fighting.
Does this mean you can't train them well and keep them happily and healthily? No, of course not - but it’s a lot harder. The majority of stallions can't be kept in groups because of the husbandry regimes on most yards, so have to live on their own. That's not good for their mental health, or their owners and riders! If someone has the knowledge and facilities to bring up a stallion, I don't have a problem with that, and I wish them luck, but I've seen too many bored, frustrated and borderline dangerous stallions who haven't been brought up correctly, and remain a liability.
Geldings, however, can be kept in groups, can mix with other horses, and are less likely to lose the plot or throw a temper tantrum. They also don't present you with unexpected foals in your competing mares...
If you decide not to have him done, you need to be sure that you're doing it for the right reasons. The majority of horses are not necessarily good breeding material - you need to take an objective look at him and decide if breeding from him is actually going to benefit the breed. If you're avoiding doing it just because you don't like the thought of the procedure, you'll need to think long and hard about whether thats in his best interest - or yours.
If you are getting your colt cut, the next decision is when to do it. There are two major concerns - the time of year, and the maturity of the colt. In terms of time of year, it’s best to do it when the weather is cold enough to prevent flies from infecting surgical wounds. Ideally, then, this would be in late autumn or early spring, but gelding him in winter is perfectly acceptable if the facilities are suitable. Regarding the colt's maturity, there is an upper and a lower limit.
The lower limit is the most rigid - except in an emergency (e.g. a strangulating hernia), I would never geld a colt until both testes had descended into the scrotum - because it’s really important to make sure you've got both! This usually happens between 6 and 12 months old, but it is a bit variable. In addition, the colt has to be strong and mature enough to survive the surgery, although with modern anaesthetics this isn't as much of an issue as it used to be. The upper limit is much more flexible. Stallions into their twenties are castrated fairly commonly, but once they've passed through puberty, a lot of the stallionish behaviour is learnt, and won't be reversed by castration, including some forms of aggression, and mounting behaviour. Sometimes, people like to wait until a colt is 3 or 4 years old before gelding, but I think that often even that is too late - although it does allow the colt to develop more muscle, he'll also be developing stallion traits. In addition, the younger the colt, the smaller the testicles, and the smaller the testicles, the lower the risk of bleeding during the op. During puberty, the testicles increase dramatically in size, and as a result, their blood supply increases accordingly; the bigger spermatic artery in a post-pubescent colt is much harder to control bleeding from.
As a general rule (and it’s a VERY rough rule of thumb!) I'd normally look to geld between a year and eighteen months old. That said, there are a lot of exceptions - I once had to sort out the castration of a four month old colt because he'd started mounting his mother... There are also a number of opinions about weaning - before, after or at the same time? In this case, I think it depends entirely on the colt in question, and it’s an area (one of many) where I'll usually defer to the owner's judgement.
Before you go any further, its a good idea to get the colt thoroughly checked out - both testicles need to be present and easily palpable; if one is "shy" and difficult to find, I usually recommend checking again in a month or so. If it’s still inaccessible, the colt may be a cryptorchid (i.e. a rig, with one undescended testis). These colts should ALWAYS be castrated, and have to be done under general anaesthetic, if possible in a clinic. This is because the retained testicle, being kept at an abnormally high temperature inside the body, is more likely to become cancerous. Also, the defect may be genetic - and if so, he'll risk passing it on to his offspring.
Once you've decided when, there's another important decision you and your vet will have to make, and that's the details of the procedure. Basically, there are two factors to decide - firstly, do you want him done "at home or away"? Secondly (a related point), do you do him under standing sedation or down under a general anaesthetic?
Regarding the location, it depends on your practice's policy and facilities. Many practices now offer castration at the clinic, but the majority of people still choose to have the op done at home. The advantage of having it done at a clinic is that the procedure can be cleaner, and all the equipment and apparatus is there; in addition, many practices charge a callout fee for coming to the yard. However, that's offset by the fact that you'll have to transport the colt to the clinic; in addition, I think it’s usually less stressful for the procedure to be done at home, assuming the appropriate facilities are available. Exactly what facilities you need depend on the technique that's going to be used.
There's a lot of debate as to this decision, and some frankly ridiculous comments from some badly-informed people out there. I'm going to talk through the options and the pros and cons.
The two main options that you'll need to think about for the procedure itself are whether to have the op done under standing sedation or general anaesthetic. In some cases, the decision is easy - miniature horses and small shetlands should almost never be done standing, because they're too small for the surgeon to get good access and control the site, for example. Draft breeds are at a higher risk of eventration (see below, when abdominal contents escape through the castration wound), and so need a different surgical technique, which may be easier under a general; and fully adult stallions bleed more so may need better surgical access - again, a general anaesthetic makes this easier. However, most colts can be done either way, so you and the vet need to decide which you prefer.
Under standing sedation, the colt is given intravenous sedatives (see my blog on sedatives) so he becomes very dopey. He will continue standing up, but his head will drop, and he is likely to adopt a wide-based stance (which makes surgical access easier!). However, its important to remember that he is still to some extent aware of what's going on, so local anaesthetic is injected into the testicles (perhaps 20ml into each one, plus some under the skin of the scrotum) or into the spermatic cord (although I find that that's easier said than done, with most colts pulling the testicles up tight to the body wall so the cord is difficult to access from outside) to numb the area. The castration is then performed with the vet working from standing beside the horse. This approach avoids the risk of a general anaesthetic, and means the horse will recover from the sedative faster. However, the degree of sedation achieved is variable, and some colts appear to be more aware of the procedure than one would like, no matter how much sedative you pour into them. There's also a MUCH higher risk of the vet or their assistants being injured - unsurprisingly, some colts object violently if they realise what you're doing...
In addition, the surgical access is poorer (the vet is having to work upside down, and largely by feel) so if there is a complication, it is harder to control it.
Under a general anaesthetic approach, the colt is sedated and then given an injection of a general anaesthetic. He'll become very sleepy, and then lie down. Once he's out, an assistant lifts up the top leg, giving the surgeon access. The disadvantage is that most vets will only do a GA on a horse if there's another vet along to monitor the anaesthetic, which may affect the cost. In addition, a GA is a risk in its own right - one study suggested that the average mortality rate from GA in a horse is 1% (although this includes colics and emergency operations - the risk for a young, healthy colt is much lower). On the other hand, the risk of injury to the vet or assistants is much lower, and the risk of surgical complications is also much reduced, as the surgeon can see exactly what they're doing.
Is either one definitively better than the other? No. However, it is a decision to take WITH your vet, as they may have a preference that will affect their efficiency. For what its worth, I've done geldings both ways, and personally I prefer to do them under general, because its safer for me and everyone else around - and if there was to be a complication, I've got a better chance of finding and fixing it at the time.
The procedure itself is pretty much the same whichever way up the horse is. Along with sedation, I give an injection of an anti-inflammatory and painkiller, and antibiotic cover (no procedure done on a yard or in a field can ever be truly sterile, so I'd prefer to make sure there are antibiotics on board when we start). In the past, vets didn't routinely give painkillers as well as the sedation (which contains a painkilling component), but personally I don't think its fair not to.
There has historically been quite a mystique about the procedure itself - probably because people are a bit shy to discuss it. As a result, there is sometimes serious confusion - remember, gelding is NOT the same as a vasectomy, and it can't be reversed... Not even (as apparently happened to a colleague of mine) if the client stops you as you're about to drive off and, holding up a neatly severed pair of testicles, asks the vet to reattach them because she's changed her mind...
So, here's a quick run through the procedure:
The area of the groin is scrubbed with a skin disinfectant, and a final check is made that both testes are accessible. Whichever one is held closer to the body is the one I'll start with, just in case it is retracted later. I'll then scrub up so my hands are sterile. Some vets wear gloves, others don't - I don't think it really matters as long as they've scrubbed thoroughly. Gloves add an additional sterile barrier; but on the other hand they can reduce your feel and grip, so it depends on what the vet is happiest with.
Once the scrotal area is scrubbed, the vet will use a scalpel blade to cut through the skin of the scrotum. There are a couple of different options from here on, but the principle is the same; to cut down through the tissue to the vaginal tunic (the membranes that surround the testis itself) and then gently pull the testicle down and out. In an "open" castration, the tunic will be opened, in a "closed" technique, it gets left intact and the testicle pulled down still inside. Once there's enough slack in the spermatic cord (containing the blood vessels, nerves etc that supply the testicle), the emasculators are applied across the cord, with or without the tunic, depending on the technique. These are a clever bit of kit that crush the cord, preventing it from bleeding, while at the same time cutting off the testicle itself.
(Quick aside here - I was doing a gelding once and, as is customary, I showed the removed testicle to the owner to show it had been done; he was a teenage lad and he fainted dead away. Interesting ethical problem there - do I try and help the unconscious boy, or do I just keep working on the anaesthatised horse who'll soon wake up? Fortunately, he recovered on his own before I had to scrub out, but he was pretty green around the gills for the rest of the morning...)
In an older stallion, most vets will put a suture through the cord to ligate the artery, but this increases the risk of infection, so we don't always put one in if doing an Open procedure. After removing the emasculators, the vet will check closely for bleeding from the stump. If there isn't any, they'll repeat the procedure on the other side. If the surgery is taking place in the field, the vet will usually leave the incision open for drainage; closing it seriously increases the risk of post op swelling and infection.
As a note, there is always a bit of bleeding after the operation. The rule of thumb is, if you can count the drops, its fine! There's also invariably some swelling of the sheath, but again, it isn't usually anything to worry about. If in any doubt though, you should contact your vet. Your vet will give you instructions for post op care, but the most important thing is to keep the new gelding moving, to reduce the swelling and encourage drainage.
The complications to be aware of are bleeding, eventration, and infection.
bleeding is pretty obvious - some oozing from around the incision is normal, but there shouldn't be any significant haemorrhage from the stump of the spermatic cord. If there is, or if there's a lot of blood - call your vet! Uncontrolled bleeding is an emergency that may require a repeat surgery to control it.
eventration, is when abdominal contents prolapse through the inguinal canal, and it’s more common in draft breeds. This is the main reason we'd do a Closed castration, as it ties off the tunic; but it does increase the risk of infection. Eventration usually involves some fatty tissue (the omentum) and although it needs urgent surgical repair, it isn't usually life threatening. Very occasionally, however, it progresses to evisceration, where loops of intestine come through. This is very serious, but (touch wood) it’s also very rare.
infection is uncommon, and usually responds to antibiotics. In a few unlucky cases, though, a schirrous cord forms, where abscesses form in the canal. These take months of management, and in the end, treatment is usually surgical removal of the infected tissue.
These complications are very rare, and even if they occur, they're usually fixable, so don't get scared of the possibility! I only mention them so you've got an idea of what to look out for.
The last thing to bear in mind is that the gelding may still show sexual interest for some weeks after castration (at least, if he was before), and may even be fertile for a time: although he can't make more sperm without testicular tissue, there will still be some "in storage" in the spermatic ducts. I always advise that a newly gelded colt or stallion should be isolated from mares for at least 6 weeks, after which any remaining sperm will have died or been flushed out, and his testosterone levels will have declined to the point where he won't have any hormonal urges.
The bottom line is this: although it doesn't seem a nice thing to do, for most colts in most situations, gelding leaves them happier and more content than they would otherwise be as entire stallions.