So tonight I'm gonna be talking about surgery in rabbits, and I'm gonna try and focus on the common surgical procedures and not go too far off. So Looking back in practise, the most common surgeries that we tend to do are new drinks is kind of bread and butter for us day in and day out, with capations and ovarian hysterectomies. In addition to these procedures doing on a very regular basis of those dental ones, and these include the standard rabbit dental that looks at modifying the crowns within the mouth, but also incisor removals.
I'll touch a little bit on extractions, and the more complex techniques of pulectomy and managing abscesses. And I also wanted to include, dealing with emergencies, so small intestinal obstructions, the classic surgical emergency in the rabbit. It isn't particularly common, but when it does present, it is a true emergency and needs dealing with immediately, so it's definitely worth being familiar with.
So rabbits, I'm sure you all know, are slightly more challenging anaesthetics than cats and dogs. They are much smaller patients on the whole and tend to have higher metabolic rate. So they tend to lose heat a lot faster and need a little bit more thermal support under anaesthesia.
They are prey animals, which complicates our management of the perianesthetic period. They don't tend to show pain as clearly. They've evolved to try and hide pains they're not appearing vulnerable to predators when they're compromised.
So it does, get in the way of us judging their pain scoring. They also tend to get high circulating catecholamine levels when they're stressed out by potential predators, and that can include cats, dogs, ferrets, birds that are hospitalised around them, but can also include us and owners handling them roughly. So we need to be a little bit cautious about how we're working with them and also try and manage hospitalisation to reduce stress levels.
So if possible, try and keep them in a dedicated ward for prey animals so they're not exposed to stresses. And this just helps reduce the amount of circulating catecholamines and reduces the complicating factors of cardiac arrhythmias and hypertension that may develop. And we also know that increased cortisol levels can cause reductions in gut motility.
And result in post-surgical anorexia and stasis. And this can be quite challenging to managing rats back eating and passing faeces if they're struggling with fertility. One of the big issues with rabbits is that they are more challenging to intubate.
They've got a very long narrow mouth with a lot of soft tissue in the way, and it's very difficult to visualise the glottis to place a tube. They also have a premised respiratory function under anaesthesia. Partly because they have very small lungs to start with, but predominantly because they have voluminous GI contents.
They are hindgut fermenters. They have large quantity of plant material passing through the GI tract at any time. And the C tends to be the large area within the GI tract that has a high lo of food.
And this can actually result in compression of the diaphragm under anaesthesia. So we need to try and manage this to try and keep them able to breathe as well as possible. There's a few ways we can try and keep the second safety levels higher.
The main thing to try and do is intubate rabbit patients undergoing surgery. And it's something that does take a lot of practise, and there will be a technique that everyone finds a little bit easier. A lot of people use blind intubation, so placing a tube through the mouth down onto the glottis.
And listening carefully to the end of the endo endotracheal tube and advancing it when you can hear a breath sound. Some people find it really easy to do. I have to say I find it a nightmare and it stresses me out and it takes a while.
So I do prefer to use visualised, techniques instead. And one of these is using an otoscope. You can just use a standard otoscope and cone.
It's down the mouth, running it along the top of the tongue until you can visualise the glottis itself. And then a guide wire or stiletti passed down the otoscope cone into the glottis and down here. The otoscope is then withdrawn and you've still got the guide wire in place and the tube is just slid down the wire and passed down into trachea that way.
If you've got a rigid endoscope in practise for arthroscopy or a rhinoscopy, then endoscopic incubation is the doddle to do, and it's certainly my favourite technique. And I use the endoscope almost like a stilet for the tube. So a 2.7 millimetre endoscope, with a 3 millimetre endotracheal tube passed over the top is used.
And you put the endoscope into them and just like with the otoscope, you this and the tip of the endoscope is passed through the glottis and into the trachea. And then like just placing intravenous cannula, the tube is lid off the top of the endoscope and straight down the trachea. It takes seconds and you know you're absolutely into the trachea because you can visualise it clearly.
Another option is using a superbotic airway device, the V gel, which is now readily available for rabbits and different. And is a valid alternative to placing in a tracheal tube. But I would recommend only using this if you've got capnography in place, because if your V gel slips out of place or kinks, it can actually obstruct airflow.
So you need to have an early warning if that's happened. Additionally, placing intravenous catheters means that you can react in any emergency situation or if you have changes in blood pressure need fluid support. The main vessel I tend to use is the lateral aricular veil marginal ear vein.
In larger rabbits, the cephalic veins also available. And in small rabbits, the lateral sofina vein. So on the outside of the hind leg just above the hook is easy to access.
And we want to try and support thoracic movements. So having them in reverse Trendelenburg posture, which is basically just having the rabbit with thorax elevated above abdomen, does help with avoiding compression of the diaphragm from abdominal contents. It's important to monitor them carefully through the anaesthesia, as with any patient.
And cat is certainly one of the most useful tools. Hypoventilation is very common in rabbit patients, and it can be easy for CO2 levels to creep up during anaesthesia, although ventilatory movements are still being observed. Temperature can also drop quite quickly and can slow recovery and complicate anaesthesia, and blood pressure can drop over prolonged anaesthesia too.
And you need to react if any of these parameters start to show any trends towards deterioration and start warming, ventilation or fluids as necessary. With regards to surgical techniques, Again, we need to be looking at analgesia, very, very important in these animals that don't show us clear signs of pain. I tend to be a lot more proactive mindra patients because I can't judge pain very easily.
So I will assume that all of my patients are going to be painful, and certainly if they're undergoing surgery, most procedures are going to cause some degree of pain. And we start pain relief proactively prior to anaesthesia. And I prefer to use multi-mode analgesia, so often a non-steroidal such as meloxicam, alongside an opioid.
And opioid choice will vary with what you've got available, but buprenorphine, tramadol, and methadone are valid options. And if we're doing particular procedures such as incisor removals, targeted nerve blocks can be very useful as well. Another thing to consider during rabbit surgery is that they don't necessarily respond to suture materials in the same way as other mammals do.
They are more prone to adhesions, particularly if cat guts. They seem exceptionally sensitive to the breakdown products of cat gut. So we avoid using this for ligatures or sutures.
And intradermal sutures are definitely the best option to use for closing the skin. If you have external sutures placed, then as part of the rabbit's normal grooming behaviour, it will remove these. And this may well happen before the wounds have a chance to heal.
So moving on to the specific procedures, castration is certainly something that we are advocating male bunnies. There have been some opinion pieces in the veterinary press, particularly vet record recently, suggesting that neutering of rabbits is not necessarily the best thing for them because many are kept singly, and there are risks to anaesthesia. But actually, neutered at a young age, while anaesthesia risk is low, under correct conditions has massive benefits to the rabbit because they're then able to bond with other rabbits and live within normal social groups.
Entire males tend to be quite difficult to bond with other rabbits because they'll try and mate with females and they'll fight with other entire males. Whereas if they're neutered, they'll tend to tolerate company and actually bond to other rabbits and form a stable group. And they are a very social species, in terms of their welfare interests, they are much better kept incorrect social groups.
Testicular neoplasia is very occasionally seen in geriatric rabbits and in most cases it is benign, but it is certainly better to prevent this by neutering rabbits when they're younger, to avoid having anaesthesia carried out when they're geriatric with potential comorbidities such as scarring of the lung, chronic pastorosis, renal damage from chilli, or even hepatic damage from coccidiosis. Owners may well want their rabbits sprayed, castrated for behavioural reasons because urine spraying, aggression, and sexual humping behaviours are often seen as well in mature males. And we tend to recommend hang out neutering at 4 to 6 months of age.
So rabbits have opening gual canals, and this can complicate sexing rabbits slightly because they can retract their testes into the abdomen, but extrusion of the penis should allow correct sexing even from a young age. From a surgical point view, it's important to be aware of the opening guinal canal, because if that tunic is left open, Vitra can then herniate through the opening guinal canal and into the scrotum. The testes are kept within a horizontal scrotum, which is different to the rodents.
So it's not in, they're not in contact with the ground when the rabbits are moving around. So it is acceptable to do scrotal incisions for cateration because these are not going to be dragged along the ground and prone to infection afterwards. Some vets prefer to do an abdominal approach, and that's perfectly acceptable as well, but it does take slightly longer to carry out.
The open castration isn't recommended for using the scrotal approach because of this openingguinal ring, but can be used with the abdominal approach because there's no tunic actually to go through. I prefer to use a modified close technique where I do an open scrotal castration initially and then close the tunic separately and that's the technique we'll focus on today. You could also do a closed scrotal castration.
But I've had a few cases over the years where we've had postoperative bleeding where the closed technique has been used, simply because ligating over a larger volume of pomatic cord and the security of the ligatures is slightly lower. So the modified close to me is my preferred one. And it is fairly simple.
There's a sharp incision made through the thin scrotal skin and the underlying fibrous tunic. And then pressure is placed onto the scrotum to extrude the testicle. So testicles then exposed.
And the breakdown of these ligaments that attach testicle to the tunic, the gubernacular fragments are broken down to separate off the testicle. This unfortunately does turn the tunic inside out, which can be a little bit of fiddle later on to manage. But you should have this completely exteriorized testicle with no attachment to the tunic.
And then you just need to ligate them. In rabbits without much fat within the spermatic cord, just a simple ligature works very well. They only place a single one.
With older rabbits that have very extensive fat. I'll spread out the sperma. Transfixing ligature encompassing vessels initially and then the whole schematic cord afterwards and just gives a little bit better seal on the vessels.
So once we've dissected the testing away after ligation, the stump is just replaced within the tunic. And then the slightly fiddly bit of reinverted needs to be done after it's been turned inside out. It does take a little bit of prodding and poking, and I tend to just use forceps to pull up the edges of the incision of the tunic, and then they'll naturally reinvert.
And once you've got the tunic completely inverted, I just place a cruciate suture over the tunic incision, thereby converting the open castration to a closed one. And once that's been done, you place tunic back into the scrotal incision. It tends to retract nicely into the abdomen, and you don't have that open inguinal ring maintained.
So the risk of herniation is very low. Once it's all been done, the skin is just closed with very fine intradermal sutures if you're particularly patient, or I just tend to use tissue glue on the wounds, and then obviously repeat for the other side. With females, a little bit more invasive technique, obviously.
But again, we do advocate neuturing of females for the same reason in males, we want to keep them in normal social groups, but also that we don't want them breeding. There's a huge number of pet rabbits that are in rescues currently and we don't need to be adding to the numbers that need. Female rabbits can be quite aggressive, both to humans and to other rabbits, so nutrient can help prevent this developing.
The key factor is relating to rabbit health. Uterine pathology is exceptionally common in rabbits. Uterine neoplasia is the best known complication of maintaining entire female rabbits, without regular breeding, but muometra is seen in the bottom picture and mammary neoplasia are all very common as well.
And unneutered a 2 year old female rabbit just last week that already had cancer changes present. So it is certainly something that should be recommended as routine. Unlike with the males, we advocate neutering at 4 to 6 months of age.
If you've got a male and a female rabbit together that are bonded, it may be worth considering neutering the female a little bit earlier. They can theory. Be fertile from 3 to 4 months of age.
So we may look at particularly large breed rabbits, female neutering a little bit earlier to prevent them breeding with any companions. So ovarectomy is potentially very valid technique to be carried out in animals that are young and have no risk of cancerous changes developing, . And will prevent you trying nearplasia developing at a later stage.
But we still do have a very hysterectomy is a standard approach in the UK. And it's a similar technique as that used for canine surgery, but I find it slightly easier because the ovaries are a lot more mobile and able to be elevated after the incision, not too much tension on the ligaments. The incision site is placed just cord with the umbilicus and typically is sighted midline between the last two nipples.
So once you go through the skin, subcut fat, and the linear alba, there's often quite a lot of fat that protrudes from the abdominal cavity, particularly in mature females. The older the animal, the larger present within the broad ligament. And I tend to use just sterile cotton buds to deflect the fat out of the way.
Grasp it with that tends to just cause it to rupture and bleed everywhere and make surgery a little bit more tricky. But these sterile cotton buds just bluntly move it out the way, and they can be used to deflect the secum as well. And just pushing all the tissues to one side and looking down abdomen on the lateral extent, you can usually visualise the uterine horn very clearly there is a bright pink tubular structure.
And once you can see it, just gentle traction, either with a traumatic forceps like ring tip forceps or just with fingertips, exteriorizes uterine body and broad ligament very easily. And then tension needs to be applied to the crannial aspect to exteriorize the ovary and the bursa. Again, in older rabbits, there's a lot of fat present within the bursa, so you may need to extend your incision if the bursa doesn't physically fit out of the original incision size.
And the fallopian tubes around the ovary and the fact they do tend to be highly friable so need to be handled gently. Once the ovary's been fully exposed, then it can be lifted up quite high and the vessels underneath visualised, and just a single artery forcep placed underneath. Where there is a large amount of fat within the pedicle, you can just manually use finger and thumb to break those fat deposits down to get a better access point to ligate the vessels or crush the fat with a pair of forceps prior to tying in a ligature.
So here we've got our ovary sitting just here, forceps underneath, and a ligature placed on the pedicle underneath. And once that's been done, a second artery forcep can be placed just above the ovary. And the ovary is sharply dissected as you would with any other space technique.
And the broad ligament should be carefully inspected before being manually broken down, just in case there are large blood vessels there. Very unusual, but in the very fat rabbits, they may have significant blood supply to the fat. In most cases, the only vessels you're then going to need to ligate are the cervical vessels.
And these are visible just along here. They're quite significant vessels, both artery and vein. And I prefer to use stick type, so tying them off separately.
Prior to ligating cross cervix. This means that you've got really secure ligatures because if anywhere it's gonna have a significant bleed, it's these vessels. Once they've been tied off, then transfixing ligature can be placed just distal to the cervix in the proximal vagina.
And this allows resection of all of the cervical tissue. But don't be tempted to go too far because the distal vagina has uterus, sorry, ureters and the cordal verticular artery that supplies the bladder running over it, and you don't want to accidentally ligate these structures. And once you've removed the uterus itself, closure is absolutely routine.
So I tend to use a continuous pattern of sutures within linear alba, and then cruciate sutures within the muscle and then intradermals within the skin. I prefer to use monocryl or viryl, partly because I come with waged on needles, so the intradermals are easier to place with a nice sharp new needle and partly because they tend to cause minimal reaction. And if there's any areas of skin closure that you have slight gaping, then tissue glue can help just close that completely.
So moving on from nutrients to dental procedures, incisor extraction is relatively common, occasionally to try and manage osteomyelitis associated with the incisor teeth, but much more commonly to try and manage incisor maleclusion. And in these rabbits that present with incisor maleclusion, overgrowth incisor teeth, it is much more preferable to actually extract the teeth and have to have them back in every 4 to 6 weeks for regular trims. With trimming, they end up with extension of the pulp cavity and eventual exposure of the pulp with trimming back to a normal level, which is not only painful but exposes the teeth to potential infection.
Don't be tempted to clip teeth. Burring is much, much better for them. If you use nail clippers or bone cutters, then you don't have control over what's being done.
And at best it maintains abnormal teeth, but it can cause pain to the animal, most importantly, risk longitudinal fractures of the whole crown of the incisor and exposed pulp or weaken perapal ligaments and allow apical infection to develop. And you don't really have any control over the shape of the crown that you leave behind. So by far superior technique is to use a dental bar.
So looking at extraction. It is a fairly simple technique, but it is quite time-consuming. It can take anywhere from 20 minutes to an hour to remove all 6 of the incisors that are there.
And the larger incisor, so the main upper and lower pairs tend to be fairly straightforward, but the tiny pet teeth, and the cord in most upper ones can be a little bit fiddly just because they're very fine teeth to remove. So I tend to look at using local anaesthesia. For these cases, this is because it is quite uncomfortable with these on his post-op, and it means we can use slightly lower plane of anaesthesia as well.
So you can either infiltrate lidocaine around the teeth or use infraorbital or mental nerve blocks to block the teeth completely. In animals that are fairly fit and well otherwise, I will prefer to use a nasal mask for these kind of cases. Simply because tracheal tube through the mouth does make it quite tricky to then access the incisors without the tube getting in the way.
And what we want to be doing is severing the periodontal ligament around each aspect of each tooth. So you can use cross the elevators, which are lovely curved elevators specifically for this technique, or you can use hypodermic needs and I use 18 gauge needles bent to the shape of the tooth that are then used like a miniature scalpel and passed on each side and front and back of the tooth. And I start off using a fairly straight needle shown in this picture.
And set the ligaments around the more superficial areas. And then once I'm getting into the deeper tissues where there's extensive curvature of the incisors, I'll then create a more curved, shape to the needle and use this and pass along the tooth. And it just takes a little bit of time just wiggling needles or elevators back and forth and breaking down these ligaments.
But with some patients, the tooth then gradually becomes mobile and once it'll actually move back and forth, it's just gently pulled along the angle of curvature of the normal line of growth of the incisor. Exteriorize it. It's important to check that you've got the pulp removed at the same time.
There should be a little jelly-like bleb right at the apex of the tooth. If it doesn't come out with a tooth, then just use some fine forceps pass down the bony channel left from extracting the incisor to grab hold of the pulp and remove it. And flushing the cavity afterwards helps remove any fragments that are left behind from an incomplete extraction.
If you find that you just cannot get that pulp out, and sometimes it's just not possible when it's not coming out of the tooth, then there's no harm in waiting for the tooth to regrow until you've got a good anchor point to then do the procedure again. And you can see in the photo on the right there's been taken from the exotic pet that blog that you can get fractures developing within the tooth, the upper right inside at the top of this photo has been fractured on removal, and this is often associated with the osteomyelitis or damage to the tooth itself. And it can complicate extraction because you don't have as much crown to get hold of to anchor and your fingers on as you're trying to break down the ligament.
Moving on to cheek teeth, and we want to avoid clipping these teeth where possible because it's going to cause further trauma to the teeth. And a high-speed diamond burr, as is used for cat and dog dentals as well as preferable. It's important to avoid working on the same area for a prolonged period of time.
So I'll usually only do 30 seconds at a time on a particular tooth to avoid overheating. Generally, you're not going to be doing particularly prolonged drilling, or burring of the cheek teeth. It's also important not only to correct the coronal abnormalities entify any other changes associated with the teeth, so any pockets that are trapping food or hair, any loose crowns that would benefit from extraction to reduce any discomfort.
Any discharge that could be associated with infection, any other lesions like carries. If you do have an endoscope, this can just help visualise the harder to reach cord on most teeth. But generally, with rabbits under anaesthesia, with a gag in place, then you can usually get to most aspects of the teeth and get a good assessment of what's going on.
So the aim of corrective dentistry relating to the crowns is to reduce any points that are present and achieve normal anatomy but not to go further than that. With the normal anatomy, the lower cheek teeth in rabbits do have very small points on them. You can see here, the lower cheek teeth are very slightly angled inwards, with very tiny points there, and we want to keep those.
They're there for a good reason. And you can see, particularly on the upper cheek teeth here, you've got various ridges and sulci in the natural anatomy of these teeth. And we don't want to go down with the burr and completely smooth those out because we limit the rabbit's capability to grind down fibrous materials such as hay.
So do focus on what the main problems are and don't try and over correct and get perfectly smooth flat surfaces. We don't want square teeth. We want the natural anatomy maintained.
Extractions of cheek teeth rarely indicated unless we've got infection present and then you don't tend to do extractions alone. And we'll talk through that with the abscess surgery. If there's repeated coronal overgrowth causing spurs, this is better managed just by trimming them back periodically or using pulectomy if that's a possibility for the case.
If you extract entire teeth, you'll end up with a diastoma forming where the extraction has taken place and a deep channel going right the way through down to the bone. These don't tend to heal up very quickly, so they end up with food being trapped in them chronically and the potential for infection and development of osteomyelitis. The teeth surrounding an extraction site will also start to migrate.
So instead of having one large gap, you end up with 2 or 3 smaller ones. And you may find that the opposing arcade starts to get irregular growth and elongation of the tooth that should or against the one that's been extracted. So we try and avoid it unless it's absolutely necessary.
And in those rare occasions where it is an appropriate treatment, a approach is often preferred for access because an intraoral approach just doesn't give you good enough access to get up and break down the ligaments to extract the tooth completely. So where possible, I'd much prefer to use pulectomy, which is the surgery to remove purely the germinal tissue associated with that tooth. It prevents further growth of that tooth, so you don't get spur reformation and overgrowth problems.
But the crown is stable within the jaw and remains in place indefinitely. And it may well be slightly shorten the surrounding tooth because the wear that's occurring isn't replaced. But once it's a little bit low, below the occlusal level, it doesn't tend to have much attrition going on with the opposing side and will maintain its place in the arcade.
So it doesn't behave in exactly the same way as a normal truth, but doesn't have the potential side effects that are associated with full distraction. Unfortunately at the moment, it's only really available for mandibular teeth. And we approach through the ventral mandible to access pulp cavity.
So the skins incised on the ventral aspect of the mandible. And blunt dissections carried out just to split between the muscles and axis bone itself. A fine incisions made through the periosteum and the location of the apex of the affected tooth is found.
Sounds potentially quite tricky. In 99% of cases, you've got marked changes associated with the toothpaste. And these tend to be discoloration of the bone to a pink or brown colour just over the pulp cavity or convexity so little bony swelling associated with that too.
So it's usually very, very easy to pinpoint where you need to go. And once you've got your site identified, then just using a sterile drill or a hypodermic needle just to take away that top surface bone and get into the pulp. To remove the pulp itself.
And this same as with the inside it's just a little lab of jelly-like material. And we'll just flush out that cavity to remove any potential remnants as well and any contamination. And the skin is then closed, and although it should be a sterile procedure, I tend to be quite cautious and administer prophylactic antibiotics afterwards.
Just to prevent any oste developing from the exposed area of bone. Dental cessation is somewhat more complicated issue to deal with and typically is an end-stage process of dental disease. So these rabbits may well have chronic dental changes, malecclusion, spurs, other issues at the same time.
And we get progressive necrosis of the alveolar bone associated with elongation of cheek teeth damaging their surrounding, weakening of the perapical ligaments. And diastoma formation. All of these changes allow migration of bacteria or favour migration of bacteria from the mouth down to the base of the tooth, survival and colonisation of those bacteria within the bone.
And once they form an infection, they start to produce pus within the bone. But that pass is not liquid, it's a solid toothpaste-like material that doesn't drain out and doesn't eat clear from that site. Infections tend to be chronic over weeks to months.
But when it's limited to within the bone, there may be nothing for owners to detect these rabbits will mask their pain very effectively. And seem clinically normal, although there may be some subtle changes like slight reductions. In eating hay, because that's the hardest thing for them to chew when they've got pain associated with the cheek teeth.
They may produce slightly abnormal faeces, so softer or irregularly shaped, or these rabbits may suffer from intermittent stasis with no clear cause. The problem tends to become clear when the infection extends from the bone, ruptures out of the jaw, and extends into the soft tissue around the face. You can get a very quick development of subcutaneous abscess once it ruptures out.
Our owners tend to pick up on this very quickly. But by the time this happens, you've had extensive osteomyelitis progressing through the jaw. And it's really, really important to take X-rays before planning any treatment to know quite how severe the infection within the bone is and what the prognosis is for that rabbit.
So we can start to see more like tumours than true infections because they behave in a similar way. They like to recur locally and they can potentially metastasized to other areas of the face as well completely removed. So what we want to try and do is completely remove all infected tissue with the perimeter completely intact to prevent local recurrence.
But it is said and done. They tend to have tracts, extending through the bone extensively and involve multiple layers of soft tissue. We may have quite extensive cellulitis present concurrently.
So we need to try and do aggressive debridement and flushing if we are going to look at surgical management of these cases. And often I'll use marsupialisation as a technique to improve surgical success. During surgery, it's useful to collect a sample of the fragment, the capsule, the abscess capsule, submit for culture and sensitivity.
Like with any deep seated infection, we want to know exactly what bacteria are there, what antibiotics we should be using. But just taking an aspirative pus or a swab of pus doesn't tend to give good results will often get culture failures. So tissue samples are much better.
So this is a classic appearance of rabbits on presentation for our treatment. And this soft tissue swelling is only the tip of the iceberg because it is the acute end stage. Development of a really chronic process.
So when you look at the X-rays, you get a much better appreciation of quite how severe the problems are. So this is this rabbit, and we can see. We have the soft tissue swelling here associated with the abscess itself that's visible externally.
But looking within the mandible, we have this area of lysis associated with chronic infection, shortening of the crowns, loss of the apices and sclerosis of the bone surrounding premolars here. So we have very, very extensive infection within the bone. So this is gonna require quite radical surgery, extracting the majority of the teeth remaining debriding the bone and clearing soft tissue fragments as well.
So my preferred approach is directly over swelling on the face, the soft tissue swelling, but very, very carefully dissecting around the capsule. And you want to stay as close as possible to the abscess capsule, because the normal anatomy is disrupted, so blood vessels and nerves may not be where you expect them to be because they've been pushed out of place by the abscess. So staying as close as you can to the abscess capsule without rupturing, it's very useful.
And I tend to just gently separate it off from the other tissues until I have the abscess capsule isolated right down to the bone. And then I'll cut off the soft tissue component to expose the cavity within the bone underneath. And this cavity then needs all the pus scooping out and the necrotic bone debriding as well.
And this can be done just with ras gently clipping away necrotic areas. And you'll often find that it's very evident which teeth you need to extract once you get in there, because the ones that are just sitting within this cavity and a very clearly not anchored to the bone anymore. And it's important to remove these teeth as well, although it's not ideal to do cheek tooth extractions in rabbits.
These teeth are nonfunctional and just going to act as chronic sequery, so much better removed in this situation. It does create quite a large hole in most cases, from the abscess cavity into the oral cavity because the teeth that would normally block that hole are being removed. So be well aware that you may have saliva or even food material moving from the oral cavity through the hole where the teeth have been extracted down into the abscess capsule.
If you can close the gingiva to create a solid barrier, that's great, but in most cases, tissues not healthy enough to support sutures or there's too large a hole to do that. So I tend to maintain these cases as marsupialization, so we open up the cavity and have a large hole, left open from skin down into the bone, just tacking skin down to the periosteum all the way round so that it's closely adherent not with bacteria or anything else sliding between skin and periosteum. And there are multiple benefits to maintaining these as open wounds.
One is that we can actually treat it toply so we can apply antibiotic disinfect and anything else we want to to that local area to try and reduce ongoing infection, because in most cases we can't 100% clear the infection within the bone. And the other main benefit is that the majority of these bacteria tend that cause abscesses tend to be anaerobic. So by opening up the air and having good air flow through there, we're gonna hamper these and try and weaken the bacteria slightly and improve our chances of success.
Alternative options where you've got a limited cavity that you're happy you've completely cleared out. There's no necrotic bone, no infection remaining. You can then use bone cement or polymethyl methacrylate antibiotics in pregnant to fill that gap so you haven't got dead space there and then completely close the incision.
And this is obviously a lot nicer for owners to manage. . But there is a higher risk of recurrence because you can't access and monitor the wound as closely.
So just going back in terms of recovery time, it tends to take a minimum of 4 weeks and potentially up to 12 weeks for these cavities to granulate up. And what we want is for the deep aspects of this wound to start granulating. And for our pockets of previous abscess cavity to gradually fill in from the base.
So the superficial area remains open until we're happy that everything else is healthy and healing well, and then it can be allowed to reepithelialize. Where you've got quite a small cavity, it may be that these rabbits need a follow-up surgery later on to reopen the cavity if the skin is trying to heal over before we got everything completely healed. It's very important to have owners completely on board before doing these surgeries, because they look a little bit gruesome afterwards, and the owners need to be fairly dedicated in terms of the time that they can spend, checking on the rabbit, administering medications, cleaning wounds, and monitoring food take.
But they also need to have financial input as well, because these have quite long follow-up periods, the veterinary fees can be fairly extensive over a long period of time. So definitely worth talking to the owners about what the potential efforts they're gonna have to put in after surgery as well as prognosis. We find that even with these fairly radical surgeries where we have good clearance, marsupialized pockets, we still only have about 75% success rate.
So 25% of these rabbits are going to have recurrence of the abscess, and usually if they recur, for our surgeries are even less successful and then euthanasia becomes our prime consideration. So finishing up on the one true emergency surgery that we see in rabbits, this is small intestinal obstruction. And this is a very acute, rapidly progressive condition.
It may initially appear similar to gut stasis where the rabbits just off food and stop passing faeces. They tend to deteriorate over a matter of hours rather than days. And they're typically caused by an instruction at the pyloris of the stomach or in the very duodenum, and this may well be a ball of hair or a foreign body like a locust bean or a ball of carpet fibres.
But in most cases, it's a desiccated faecal pellet, and this may relate to abnormal citroph production. So that when they're producing these soft faeces, faeces that they should ingest, they're getting some waste dry faeces produced at the same time. So that when they have this reflex action of bending round to the anus and taking in the strophs orally, they'll take in a faecal pellet, a waste fibrous pellet at the same time.
And unfortunately, these pellets seem to be the exact diameter of the small intestine. So they're not very easily broken down by the stomach and they can lodge within the proximal duodenum and cause a complete obstruction. So so they tend to progress quite rapidly over 1 to 4 hours, and rabbits will often present either as acute death or those that are picked up quite quickly by the owner of shocked depressed rabbits, and they tend to be bradycardic, markedly hypothermic, usually less than 34 degrees by the time they get to the clinic.
And with the very thready weak pulse, they may have pale or cyanotic mucous membranes, and they're often poorly responsive. On palpation, there's a distended stomach, that this can be distended to a varying degree, so from slightly above normal size through to dramatically extend to taking up a huge portion of the abdomen. But the stomach is always firm on palpation and in healthy rabbits or those with stasis, the stomach often feels doughy.
One of the key factors that we take into account is the blood glucose, and this tends to rise very quickly. And will usually be over 17 mm per litre. And in many of these cases, by the time they present, it's well over 20.
And this is a strong indicator that we've got an obstruction. And these GI obstructions in rabbits are to canine GDVs and they need very prompt correction to prevent metabolic compromise and necrosis of stomach wall developing. So what we tend to do is have them in dorsal recumbency from midline laparotomy.
And we will intubate these invariably and maintain them with a thorax elevated above the abdomen. These guys are gonna be very, very susceptible to hypoventilation, because this enlarged stomach is pushing on the diaphragm and further limiting pulmonary expansion. So these rabbits tend to be hypercapnic and acidotic.
So if you don't have catnography available for monitoring, then ventilate them automatically assume they are going to be hypercapnic and try to keep them ventilated throughout surgery or at least until the stomach has been decompressed. And our surgical site is going to be on the ventral midline and I make a large incision from ziphoid down to umbilicus because you need good access to the whole of the intestinal tract. Usually, you can identify the region where the obstruction is lodged very, very easily.
Unfortunately, this is a postmortem photo on the right, which is why it's not quite a sterile procedure, but it shows the classic position within the proximal duodenum. So what I'll usually do is open up the abdomen with a large incision and go down the rabbit's right side and just flip the pylorus up towards the midline so I can visualise it more clearly. And you'll find an area of congested or hemorrhagic mucosa either within the pyloris or proximal duodenum which indicates where your obstruction is lodged.
And we used to look at doing incisions into the small intestine and physically removing the obstruction and sing a closed, but this has a high complication rate in rabbits. They don't tend to have good healing. There's a high risk breakdown on small intestinal wall.
So we tend to get septic peritonitis a day or two post-surgery or end up with stretch of small intestine rabbits present with repeat obstruction. So what we tend to do now is actually milk this pellet right the way through the small intestine down into the larger diameter areas of that. So it's a little bit of a fiddle, because they have quite a long, small intestine.
So it takes about 1015 minutes to manually manipulate this pellets of firm material down through the small intestine. Surprisingly, considering that they lodged apparently convincingly in these rabbit cases, they are fairly easy to move down just with using finger and thumb behind. The pellet, just gently pushing it along small intestine.
Once you've got through all of the small intestine and you get to the scum, the pellet moves into the scum, and then the gut from then on out is much larger diameter. So that pellet isn't going to lodge anywhere. We found really good success rates, about 80 to 90% of these cases, recovering really well.
I've had one rabbit with this technique having a repeat. Obstruction, but it was a different site and didn't seem to be related to the original surgery, that we carried out just by milking it through. So if you can carry out surgery promptly in these cases before they get to the cyanotic collapse stage, there is a reasonable success rate, but it is worth warning owners that it's very difficult to gauge what their metabolic status is and although it'd be lovely to do blood gases, biochemistry, and extensive investigation first, actually, what you need to do is get them into surgery quickly to stop them decompensating.
So again, like with GDVs, the surgical technique is straightforward, it's just getting the patients to cope with that and making sure. That they're in the best position not to have any secondary compromise. So once we've done that, I flush the abdomen with warm saline afterwards, partly to maintain visceral hydration.
The viscera may well have been exposed for a prolonged period of time as I'm moving things through, but also because just handling the guts repeatedly all the way along the small intestine causes minor trauma and it may leave fragments of foreign material behind, particularly powder from surgical gloves, and we don't want any potential for adhesions postoperatively. And then we close the abdominal wall in three layers. There's no gut closure to perform.
I tend to use simple interrupted sutures in the linear alba in these cases just because there's a very long incision to close and using a continuous pattern. I'd be a little bit concerned about whether these rabbits as they jumped around post-surgery could pull sutures through and we could have a wound breakdown. It's difficult to persuade rabbits to do convincing cage post surgery.
We tend to maintain them in hospital on syringe feeding until they start passing faeces, which is a good sign we're getting the gut up and running and everything moving through again, and have the rabbit taking food reliably. And ideally, this will be a rabbit self-feeding and taking its normal intaking, but often we'll send them home a little bit earlier, as long as we're happy the can continue syringe feeding. All we want is for the rabbit rabbit to get its nutritional requirements.
And if they can go home springe fed, they're going to be a lot less stressed and recover faster. So that's it. That's the most common surgeries that I see in practise.
But if you've got any questions about these or if there's anything else that you're seeing commonly that you want input on, then I'd be happy to take any questions. Murray, thank you very much. That was, as always, very, very interesting.
You, you've already answered some of the questions that came through from people. But Greg asked, when you were talking about the, the dental abscess and, and the surgery underneath, what antibiotics do you use, for these abscesses, especially for the fact that there is only the licence of n refloxacillin. In an ideal world, we'd send samples away for culture, but a lot of the time, unfortunately, budgets tend to be the limiting factor.
So sometimes we have to choose best guess. I tend to use two things commonly. The first option is a combination of Beittrol with metroido.
And obviously, beryl or other forms and reflux in of the licenced options in most cases, because we've got strong evidence based in the public the published literature that anaerobic infections are common, there is good justification to use metronidazole off licence. And the other option that I will sometimes use in these cases is azithromycin. And again, it's used off licence, but we know that's concentrated by macrophages tend to get higher concentrations of antibiotic at the site of infection.
So I can justify many cases using that over and refloxacin. OK yes. Yes, sorry, I interrupted you.
I should say, ideally, say we will be using antibiotics that are designated by the culture and sensitivity. But I mean there's nothing wrong with you starting with in refloxacillin and that until you get your culture back. No, absolutely not.
There is a potential to inhibit bacterial growth of the culture sample if the rabbit's been on antibiotics previously, but we tend to find if they're resistant to refluxes in, then we get culture samples successfully grown anyway. Yeah, yeah. And what about the old, and, and I stress old technique that people always had the idea that you had to install some form of antibiotics locally when you were dealing with abscesses in, in rabbits.
That is one option. There's certainly, a valid place for using and things like plaster of parrots, polymethyl methacrylates, bone cements that have antibiotics added into them and sealing the hole within the bone. But often you have microscopic channels extending from there, and there have been some studies showing that actually the rate of illusion from polymethal in factrate another, compounds isn't as long as we initially thought.
So you may not get as persistent antibiotic concentrations locally. So I will still tend to maize over packing wounds in most cases. OK.
A question just comes through. Would you ever consider using Sivofecin, as an antibiotic? We have used, I'm assuming it's a cephalosporin.
It's not one that I've used particularly, but we have used other cephalosporins where we've had culture results that indicate we need to, and certainly for abscesses, we've had multi-resistant pseudomonas come back that's only been sensitive to some cephalosporins. So I've used ceftazadine quite regularly in those cases. I haven't used vein personally.
OK. Terry's asking on suture material and that. Do you tend to find any problems with viral reactions intradermally?
No, I haven't actually. I used to use that as an absolute routine for about 7 or 8 years and didn't have any problems. I've switched to Makrol recently just because that's what we tend to stock in practise, but I haven't seen any benefit of one over the other.
And I think monochrol, as far as I personally have found in rabbits, it seems to last longer than Viryl does. It dissolves later. Yeah, and again, that hasn't seemed to cause any problems.
We normally want to solve fairly quickly in rabbits. They tend to heal pretty quickly, but I've not had any issues with persistence of monorel. OK.
Carmen's asking, what dose of Metacam would you use after you've marsupialized an abscess? I would tend to go for the higher end of the range, so 0.6 to 0.8 Migs per gig twice a day.
Yeah, I think the the key there which everybody tends to, to shy away from or forget is the twice a day in bunnies. Yeah, absolutely. There have been some quite nice Pharmacokinetic pharmacodynamic studies on meloxicamin rabbits showing that it just doesn't last for 24 hours.
So if it's only being used once a day, you're going to have a rabbit that has waning levels and pain resurfacing. It's actually quite amazing. I've, I personally have seen huge differences in bunnies that, you know, are on twice a day dosing as opposed to once a day.
Yeah, absolutely. And you can often get away with lower doses twice a day. So for chronic cases, things like osteoarthritis, whereas we want to maintain rabbits on, you know, up to 1 milligramme per kilo per day as a single dose and not getting good pain relief.
Just going to 0.2 mg per gig twice a day gave much, much better pain relief. So I think the frequency of dosing is very, very important for rabbits.
Yeah, absolutely. But Murray, thank you once again for a fabulous webinar. As always, lots to learn and, and great to listen to you.
So thank you for your time. Thank you. Folks, that's it for tonight and as Bugs Buzzy goes, I can't remember the full saying properly.
If I don't see you through the week, I'll see you through the window or didn't that what did you say? Chow doc or something like that. So from me, Bruce Stevenson, thank you for attending the webinar and we'll catch you again on another webinar.
Thanks folks. Bye bye.