VetInfo Digest

VetInfo Digest March 2007

Table of Contents:

Anesthesia

Spay/Neuter

Orthopedic Surgery

Herniated Discs

Cancer surgery

Declawing

Anal Sac Surgery

Tips for Pet Owners

This Month’s Note:

A chance to cut is a chance to cure. This is an old adage that is usually one of the first things that veterinary students hear when they have surgical classes. Surgery does often provide a real chance at a cure. To put this in perspective, many cancers are truly cured by surgical excision. In fact, the cure rate for cancer is actually quite high due to the fact that surgical excision is considered in cure rates. Removal of objects stuck in the intestines, removal of bladder stones and many other examples of complete surgical cures exist. On the other hand, most disease conditions can’t be treated through surgery and there are other examples of disorders that shouldn’t be treated surgically, at least in all cases, where surgery is attempted, anyway. Surgery is extremely difficult to study in the most objective ways, since there is no ethical way to perform surgery on a control group just to make a study scientifically valid. Right now, surgery remains one of the major areas of medical care in which most of the information about many procedures, at least in regard to response rates, long term outcomes and other important considerations has defied scientific scrutiny. The chance to cut provides a chance for a cure – but for many surgeries no one really knows how much of a chance.

Introduction

I have not written much about surgery over the years that I have written the VetInfo Digest. There are a number of reasons for this but the biggest one is that I am almost a self-taught surgeon and my opinions of surgery do not match the mainstream thought in many instances. I do almost all the surgery in our veterinary clinic but it is still a small part of what I do during the day, making me less than an expert on surgical techniques. Still, I do think that some of my thinking is valid and that there is a strong interest in some of the surgical procedures that are routinely performed in veterinary medicine so this month I am going to devote most of the VetInfo Digest to surgical procedures.

I have a few clients who insist that if their pet needs surgery I should be the one to do it. While I find their trust in me flattering, there is no way that a rural practitioner can ever be good at all of the surgical procedures available today. My thinking is that I should stick to surgeries that I am likely to do on a fairly frequent basis so that I stay competent to perform them and that I should refer less common procedures to surgical specialists. Once in a while I have to argue with a client over this approach but there is no question in my mind that my patients are better off if I don’t learn new surgical techniques by operating on them. Your vet is trying to give you the best option when referral is offered.

Anesthesia

I have covered anesthetic procedures occasionally but I do want to start off with a small discussion of anesthesia to cover a couple of issues that are of critical importance to surgical planning.

The first issue to consider about a procedure involving anesthesia is whether or not your veterinarian has a person who is dedicated solely to monitoring anesthesia during the surgical procedures. I think that this person should monitor one patient at a time but it is not too unusual for the person monitoring anesthesia to be responsible for more than one patient. I am comfortable with a certified (licensed) veterinary technician as an anesthetist but a veterinarian other than the surgeon is even better. This is not always standard practice in veterinary medicine. You might be surprised how often anesthesia for surgical and dental procedures is “monitored” by the person doing the procedure. It is hard to do a good job of two things at once and this is not an ideal situation. Monitors such as pulse oximeters, continuous blood pressure measurement, ECGs and respiratory monitors are not a substitute for a person who understands anesthesia watching the pet closely during surgery. It is important to ask who will be monitoring the anesthesia during any procedure in which general anesthesia is necessary and if necessary to offer to pay to have a dedicated anesthetist for your pet’s dental or surgical procedures.

The second thing that must be considered is whether or not to have preanesthetic lab work done. It is hard to argue against doing this when thinking about one individual pet, since it is always possible that a pre-existing condition could show up that might alter surgical or anesthetic plans. On the other hand, there is little question that the overall cost effectiveness of preanesthetic lab work is low and that when viewed from an economic standpoint it doesn’t make a lot of sense unless you put a value of “priceless” on any pet who suffers consequences due to the fact that lab work was not done. Of course, for some of us, priceless is an adequate description of how we feel about the value of our pets.

The minimum database recommended by most anesthetists is a total protein measurement and some measurement of red blood cell volume or numbers, such as a packed cell volume (PCV), hematocrit (HCT) or red blood cell count and hemoglobin measurement. While other tests may be more reassuring there isn’t much evidence that pre-anesthetic testing actually reduces mortality associated with anesthesia.

Pre-anesthetic lab work sometimes leads to really poor decision making when values that are not normal show up in the lab work. If a veterinarian pushes for the lab work and it comes up abnormal there is pressure to do something about it prior to surgery. Often, the choice that is made is to delay surgery or dental work in an effort to identify and treat the source of the abnormality. Sometimes truly necessary procedures are delayed or cancelled while futile efforts are made to determine what is happening with lab values. In more than a few of these cases correction of the problem surgery was scheduled for and rechecking the lab values later will reveal that the problem was either minor or responded to the surgery. It is extremely important to recognize that finding an abnormality just means that it has to be considered in decision making, not that it must preclude necessary dental or surgical procedures. If a surgical procedure is truly necessary it may be important to proceed with it, even if laboratory work reveals that there is some pre-existing kidney problems, liver damage or other disorder.

Spaying and Neutering

The most familiar surgical procedures for most people are spaying (female) and neutering (male) procedures. Many of my clients take these procedures for granted, assuming that they are so routine that they do not present a danger to the pet. This is not true. Almost all of the anesthetic deaths that have occurred in our practice have been associated with one of these two procedures. This is a major surgery performed on a large segment of the population. Any problem that exists in a patient that might lead to anesthetic complications may be unmasked by the anesthetic procedure. It is likely that at least some of these patients would have developed identifiable problems as time went on. This is usually the first major surgery that a puppy has. It is also the surgical procedure most likely to be “price shopped”. It has always struck me as tragic that the surgical procedure with the most chance of a significant problem developing, because it is usually the first surgical procedure involving general anesthesia in a patient’s life, is also the one in which price sensitivity makes it difficult for veterinary practices to perform all of the safety precautions that might make the procedure safer.

Many things that would increase the safety and decrease patient discomfort are not a routine part of spay/neuter procedures simply due to the costs. Ideally a surgical patient should have an IV catheter in place during the procedure to ensure rapid access to a vein for administering medications if a problem occurs during surgery. Pain relief medications pre and post surgery should be standard. A skilled anesthetist should monitor the patient throughout surgery. Good quality suture with a needle attached is easier to use than the bulk suture that has to be threaded through the eye of the suture needle, causing the knot to be dragged through the skin on every pass – but it is more expensive to use high quality suture even though the patient will benefit from less irritation and a lower chance of reactions to the suture material in the post-operative period. Patient heating systems should be used during surgery to help prevent hypothermia and complications resulting from hypothermia. Many of these things would be standard procedure during most surgical procedures but are offered as options, if they are offered at all, for spay and neuter patients. The need to keep the cost of the procedure competitive with the local surgeon who places the lowest value on his or her services causes this problem. You can ask for these options during surgery, if you like. Most practices will provide these services upon request, although there is likely to be an additional fee. If you do price shop this particular surgery, make sure that you know the minimum standards you expect for surgical care and that you are getting the price for surgery with those standards as you compare one veterinarian’s prices to another.

I have some clients who truly have a hard time deciding whether a spay or neuter procedure is right for their pets. They want to know the good things that might occur due to surgery, as well as the bad things. While overall there is almost no question that spayed and neutered dogs and cats live longer and healthier lives, there are some downsides to these procedures. The risk of an anesthetic complication exists for all pets undergoing these procedures.

For female dogs there is an increased chance of incontinence developing early after spaying. The rate of incontinence is somewhere between 11% and 20% (Fossum, 2002) but is usually responsive to therapy. Some behaviorists believe that a female dog with a tendency towards aggression will sometimes be more aggressive after being spayed. Although it seems rare there are occasional reports of radical personality changes in cats undergoing spay procedures which may be due to anesthesia rather than surgery. Female dogs neutered early (less than 5 months of age, approximately) may have later problems with irritation in the vulvar regions as the vulva may remain small, leading to problems with skin infections if the dog becomes even slightly overweight or if incontinence occurs. There is also evidence that spayed female dogs are more prone to cruciate ligament injuries later in life. It is unclear if this is due to increased weight and decreased activity or due to other factors such as hormonal changes due to the spay procedure.

Female dogs spayed before the first heat period have a dramatic reduction in mammary cancer later in life. Spaying later still seems to help reduce the incidence of mammary cancer but the effect becomes less and less with each heat period. Spayed cats rarely develop mammary cancer but a link to spaying prior to a heat cycle has not been documented to the best of my knowledge. Roaming is less of a problem with spayed females. The reduction in unwanted pregnancies is a major benefit, especially given the pet overpopulation problems in most places. Spaying nearly eliminates the risk of pyometra (uterine infection) which affects about 8% of unspayed female dogs during the course of their lifetime and is a very serious disease in dogs. This problem occurs in cats but not nearly as frequently as in dogs.

A spay procedure is an ovariohysterectomy. This means that the ovaries and uterus are removed. I sometimes have clients ask me if it would be acceptable to just remove the uterus as they feel that retaining the estrogen levels associated with intact ovaries would be better, apparently based on findings that this is the case in people. For dogs the complications associated with the way their heat cycles work and the attractiveness to males every seven months or so usually make this an unacceptable procedure. Removing the ovaries alone would work in many patients but there have been problems with uterine infections when the uterus is left in place and since it serves no real function without ovaries it just doesn’t seem like a good idea to leave it in place.

In males, there is a slight increase in prostatic cancer associated with neutering. Prostatic cancer is not a common problem in dogs so this is not a major concern but it does seem to occur. Male dogs neutered young may retain juvenile features which some people consider a plus and others a minus. Male dogs neutered at less than 8 months or so of age grow slightly taller than intact males. This isn’t usually a problem but some people do seem to get upset when their neutered male exceeds breed height standards and there is some concern that this effect might contribute to the incidence of hip dysplasia and elbow dysplasia in susceptible individuals. Castration is a good prevention for aggressive behaviors between male dogs but is less effective at preventing other forms of aggression. It cuts down dramatically on roaming behaviors which limits death due to fighting, being hit by cars and being shot by irate female dog owners. Castration eliminates benign prostatic hypertrophy, a condition that affects almost all intact males as they age, which can lead to problems with urination later in life. Again, the positive benefits in population control are important for male dogs as well as female dogs.

There is almost no question that spaying and neutering provide more benefits than risks but these are major surgical procedures and it is reasonable to try to alleviate some risks by choosing a proper time to spay. One additional advantage of waiting until at least five months of age in cats or six months of age in dogs to spay or neuter is the ability to assess whether decidous (baby) teeth need to be removed due to retention when the permanent teeth erupt.

Orthopedic surgery

The first thing to point out about orthopedic surgery, at least for fractures, is that it isn’t a good idea to try to avoid it by applying casts or splints. Dogs and cats cannot tell you when a cast is rubbing or the tape on a splint is cutting off circulation. These are significant complications that can and do lead to loss of the affected limb. I practiced during a time when orthopedic surgery was not as widely available and I have applied hundreds of casts and splints, most of which did work. The ones that didn’t, though, were complete and total disasters. Surgical implantation of plates, wires, screws, pins, etc. doesn’t always work but the complication rate is lower, patients are relieved of pain faster and are more comfortable overall when a surgical repair of a fracture limb is possible.

The second thing to point out about orthopedic surgery is that repair of ligamental injuries doesn’t work very well. In long term studies none of the procedures for repairing ruptured cruciate ligaments result in a reduction of arthritis when compared to pets in which surgery was not performed when the pets are evaluated five or more years after surgery. These studies have not been done for the newest of these surgeries, tibeal plateau leveling osteotomy (TPLO) and there is some hope that it will turn out to be the exception to this statement. At the present time I really believe that if you can’t afford TPLO surgery or you can’t find a surgeon in your area to do this surgery, it is not worthwhile to pursue repair of a ruptured cruciate ligament by other means. One complication with this philosophy is that it does sometimes help to remove injured cartilage when there is a severe tear and so it may be necessary to do exploratory surgery of the knee, anyway. If a cartilage injury seems likely it may be just as well to attempt some form of stabilization at the same time. TPLO surgery doesn’t attempt to repair the injured ligament. It is a method of altering the function of the stifle (knee) joint in a way that makes the ligament less necessary.

Orthopedic surgery is a fairly common procedure and many veterinary practices have a veterinarian on staff who is comfortable doing orthopedics. There are a number of different orthopedic procedures and it is rare for a practice to be proficient in every single one of them, though. If your local veterinarian suggests that a surgical repair requires referral to another practice or to a board certified surgeon, it would be a good idea to heed that advice rather than insisting that your local vet perform the surgery to the best of his or her ability.

Surgery for herniated discs

If you own a breed that is prone to disc herniation it is a good idea to decide what you are going to do if disc herniation leads to paralysis before the event occurs. When a disc herniates and leads to paralysis or significant weakness in affected limbs it is necessary to get a proper diagnosis, perform necessary diagnostic studies and proceed to surgery within 48 hours for maximum benefit. After 48 hours the long term prognosis for very successful surgery drops off and gets worse and worse as time goes on. Over the years we have had a number of patients with paralysis from herniated discs go to surgery and the great majority of these patients had very successful surgeries. It is worth doing surgery so it is important to be prepared for it. This surgery often costs more than $2500 so it is important to know in advance how you are going to pay for it if the need arises. So if you have a dachshund, beagle, Pekingese, cocker spaniel, French bulldog or Lhasa apso, you might consider having a back surgery savings account, just in case. If you see signs of severe back pain or paralysis on a weekend or other time you can’t see your regular veterinarian, do not wait a day or two to make an appointment. If possible take your dog to an emergency clinic associated with a surgical referral hospital but no matter what you have to do, find a veterinarian who can refer you to a surgical specialist as quickly as possible. Time really is important when these injuries occur. Remember it isn’t just the time it takes to get the first exam, it is also the time involved in making the referral and getting to the surgical specialist. A few hours delay at the beginning of the process can result in an inability to get the surgery done in the window of opportunity for best success.

Cancer surgery

If your vet suspects that your pet has a cancer that could be malignant you have several options for making a definitive diagnosis and for subsequent surgical procedures. You really need to think about these options in advance of the first attempt to deal with a cancer if at all possible.

When dealing with a tumor that can be visualized (primarily skin cancers) it is best to do a biopsy from a site on the tumor that will be completely removed if subsequent surgery is performed in order to make a surgical plan for removal of the tumor. If it turns out that the tumor is benign the surgical plan is much different than when the tumor is identified as a malignant tumor. This is particularly important for cats who are suspected of having a vaccine associated sarcoma or fibrosarcoma and for dogs with suspected mast cell tumors and melanomas.

The primary reason for doing a biopsy first is that very few surgeons will take sufficient margins around an unidentified tumor when performing an initial surgery unless they know in advance that it is a malignancy that requires this type of surgery. Even with a biopsy I think that it is better to get an oncologic surgeon to remove the vaccine associated sarcomas and fibrosarcomas in cats because there is really only one chance to do a good job removing those tumors. The surgery must be very aggressive, including removal of underlying bone if it is within the suspect margins. Most general practitioners won’t remove shoulder blades or vertebrae, but cancer surgeons will. If you are going to have surgery for these conditions you might as well do it right.

For internal tumors there are often options for obtaining a biopsy sample prior to tumor removal. Samples from urinary bladder tumors can be obtained by catheterization or by cystoscopy. Endoscopy can also allow biopsy of tumors in the respiratory or digestive tracts at times. Tumors in organs can be biopsied using ultrasound guided biopsy techniques in many cases. A drawback to biopsy of tumors in organs is that the biopsy needle may drag tumor cells into other tissues as it is retracted through the body. Some surgeons prefer to do exploratory surgery as a first step when they have reason to suspect that a tumor that may be a malignancy is present in an organ due to this complication.

It is possible to remove skin tumors using aggressive surgical margins and so it is sometimes tempting to skip the diagnostic biopsy. This can be justified for tumors with a very typical appearance or that resemble tumors present in the same patient that have been previously biopsied. If your veterinarian isn’t worried about removing a particular lump or tumor without a prior biopsy it is reasonable to take his or her advice. However, if your veterinarian isn’t reasonably sure of the tumor type or suggests a biopsy in order to develop a surgical plan, it is generally better to take that approach.

Declawing

Some people think that declawing is inhumane. Others think it should be a routine procedure. I think that it is a procedure that should be done only as a last option but that it is sometimes necessary to allow a cat to stay in a home. Unless there are going to be laws preventing cat abandonment, declawing is a better option than taking the cat to an animal shelter or letting it loose on the streets. Most cats will use scratching posts if they are located in an area of the house the cat frequents and some effort is made to encourage the cat to give the post a try. Putting a scratching post in the basement or hiding it in a corner of an unused room isn’t likely to result in much use. I don’t intend to debate the morality of the decision to declaw or not to declaw. I just want to point out some important points about the surgery for those that might contemplate it.

Declawing only works well when the entire nail bed is removed. The best way to ensure this is to remove the bone at the tip of the toe, equivalent to removing a finger at the joint nearest the fingernail. Cats have the advantage of having a protective sheath over this area so removal of this much of the digit does not completely expose the remaining toe to repetitive injury. Still, it should be obvious that this is a surgery that will cause pain for a few days.

There are several methods of declawing. The use of a guillotine type nail trimmer to remove the nail and underlying bone is one common method. Alternatives include dissection and removal of the claw and last digit using a scalpel blade, surgical laser or electrosurgical unit. Some older surgeons favor the guillotine clipper removal as it is fast and leaves a portion of the bone but it has to be done skillfully to prevent nail regrowth. Personally, I strongly favor surgical dissection, at least when performed by someone who is good at the procedure. Using a laser or electrosurgical unit to perform the dissection reduces the amount of post-operative bleeding and the need for bandaging.

Other than the slight risk of anesthetic death or complications, the biggest risk associated with declawing is the post-operative bandaging. Cats can not tell you when a bandage is uncomfortable or when they stop feeling their toes entirely. Therefore, they are susceptible to injuries that occur when the bandage is too tight, twists and constricts or causes circulatory problems for any reason. In some cases where this occurs it is necessary to amputate the leg beyond the area damaged by a lack of circulation. Pay close attention to bandages. It is always better to remove them if you are suspicious they are causing a problem. They can always be reapplied later. Any bleeding that occurs when the bandage is removed may be frightening but it is almost never life threatening.

As you can imagine, cats who have been declawed experience pain for a few days after the surgery. Pain relief is very important. All cats undergoing declaw procedures should have pain relief medications for several days post-operatively.

If a cat who has been declawed manages to get outside will it be in danger? I really believe that the risk of going outside for declawed cats is exaggerated in many people’s minds. Cats survive outside primarily due to the use of their brains. They use their claws only when they weren’t paying enough attention to dangers. Fortunately, for most cats this isn’t a major problem.

Anal sac removal

The anal sacs are pouches on either side of the anus that contain a secretion that probably helps dogs and cats “personalize” their stool scent as part of marking their territory. When all is going well there is no need to worry about these sacs, at all. Unfortunately, in both dogs and cats, the ducts from the glands to the anal opening get blocked up and cause problems.

There are reports of dogs, and possibly cats, who appear to be allergic or sensitive to the anal sac secretions. At the present time I am very suspicious of these claims but at least one veterinary dermatologist has published papers on this topic and recommends removal of the anal sacs routinely for dogs with prolonged itchiness or other signs of persistent allergic dermatitis. We have tried this out of desperation in a handful of patients over the years with no success that I can remember.

Anal sac rupture is a fairly common problem in dogs. It is less common in cats but can be a serious problem for them when it occurs. Most dogs with infected anal sacs show some sign of discomfort for at least a day or two before the anal sacs rupture. If the condition is discovered at this stage there is a chance that medical treatment will resolve the problem. Most of the cats we have seen with anal sac ruptures showed no signs that the owners were aware of prior to the rupture of the anal sac.

When anal sacs rupture they usually produce a blood tinged pus or exudative drainage from a hole located about an inch to the side of the anus and one to two inches below it (about the 5 o’clock position or the 7 o’clock position if the anus is considered to be the center point of a clock face). Most of the pet owners in our practice whose pets have this problem have no idea what is going on. Some assume that the blood they are seeing is coming from the rectum or the urinary tract. Others think their pet was injured in a fight or was shot. Cats frequently do have fight wound abscesses in this same region so it can be hard to decide what the underlying cause is when a cat comes in with a wound near its anus. In most cases dogs with draining tracts in this region have anal sac disease.

There are several surgical procedures that can be used to remove anal sacs. The sacs are very close to the rectal wall, they are located in the muscles that control the anal region and they are just close enough to the nerves controlling this region that it is possible to cut the nerves if they are not identified or the infection has made tissues hard to identify. It is imperative for long term success that every little bit of the anal sac be removed or it is likely that a draining tract will develop where anal sac tissue is left behind. For these reasons some veterinarians are very reluctant to remove anal sacs and will refer patients to a surgical specialist for this procedure.

In one anal sac removal procedure one blade of a scissor is introduced into the anal sac duct with the scissors open. When the tip of the blade stops at the end of the anal sac the scissors are closed to make a cut through the skin, surrounding muscle and the anal sac, which exposes it and allows it to be dissected free. This procedure is associated with a higher rate of complications than carefully dissecting the gland and duct free from the surrounding tissue after making a skin incision over it but it is much faster. Personally, I think it is worth paying someone to take their time to carefully dissect the gland free. To the best of my knowledge we have never caused a serious complication using the dissection procedure. There are also ways to use dye markers or fillers to make the gland more visible and ostensibly easier to dissect but these also seem to cause more complications, at least when I do the surgery.

Anal sac removal should probably be considered when a dog has two or more infections affecting the same anal sac. It is also necessary when cancer affects the anal sacs. It is critically important to remember this because anal sac cancer tends to metastasize very quickly. If your veterinarian is reluctant to perform surgery insist on referral to a specialist for a second opinion. Even though metastasis is a big worry we have removed several anal sacs with apocrine gland adenomas (an aggressive cancer) before it managed to spread. I think that anal sac removal probably should be considered more often than it is for dogs or cats with chronic anal sac impaction problems but the potential for complications is real and this tends to make some people reluctant to consider surgery.

Anal sac removal is not a technically difficult surgery and most veterinary practitioners probably have the surgical skills to successfully perform this surgery. However, it is a surgery that requires a patient perfectionist for best results. It is therefore another one of those surgeries where you probably should take your vet’s advice if he or she recommends referral to another surgeon.

Perhaps this is more of a problem working in the South than it might be in other areas of the country, but you would be surprised how many people hear the words “your dog has a problem with its anal sex” rather than “your dog has a problem with its anal sacs”. Some folks are very offended until it is possible to explain to them that the problem is an anatomical structure rather than a canine behavioral problem.

Things you can do to help your pet have a better surgery experience:

Make sure that you can be reached all day on the day of the surgery. Make sure your vet has the contact information he or she needs to reach you.

Follow directions regarding feeding prior to surgery and also giving water.

If your pet is receiving antibiotics or is on a medication for a chronic problem such as hypothyroidism it is usually best to give the medications on the day of surgery. Check with your vet if your pet is on any medications on a regular basis, just to be sure.

Ask about pain relief if none is provided. Insist on it even if your vet doesn’t think it is necessary for any surgery that seems major to you.

Know who to contact and how to contact them if an emergency should occur during the post-operative period. Write down the contact information if you don’t think you can find it quickly in the phone book or in the records you keep for your pet.

Ask to have an anesthetist (a certified technician experienced at monitoring anesthesia is OK) present during the surgical or dental procedure. Pay extra for this if necessary. Make sure your vet knows that you mean a certified technician NOT doing the dental procedure at the same time!

Bring your cat to the veterinarian’s office in a crate. Anesthesia can disorient cats and even cats who are normally quite calm can be very agitated after surgery. Think about bringing a crate or having someone come with you who can restrain a dog in the car on the ride home from surgery. This can be especially important for orthopedic surgeries.

If your vet hospitalizes your pet before or after surgery, make sure that someone is at the clinic or hospital to observe patients during the hours the clinic is closed. Otherwise, what’s the point of hospitalization? A pet is better off at home where someone is at least there to see any complications that arise from surgery.

If you suspect a complication call your vet. He or she wants the procedure to work properly and will almost always prefer to talk to you about possible complications rather than dealing with a more serious problem later.

Thanks for your Support!

The VetInfo Digest is published by:

TierCom, Inc.

P.O. Box 476

Cobbs Creek, VA 23035.

The opinions expressed in this newsletter are those of Michael Richards, DVM., author.