Sunday, October 31, 2010

Veterinary fact of the day: playing detective with bladder infections

I’m learning about urinary tract problems at the moment. I love this section, because the guessing game of finding out where the problem is can be so much fun. As a small example: an owner brings in a female dog who has been asking to go outside more often. Recently the dog had an accident in the home and there was blood in the urine. You suspect a urinary tract infection, and are curious about where the actual infection is: kidneys? ureters? bladder? urethra?

We like to know if the infection is in the kidneys, because that can be a much more serious and hard to manage infection, so it is better to be prepared at the outset. Do you have to do an ultrasound to see what shape the kidneys are in?

One thing you can do instead is watch the dog pee. Does the blood appear in the urine stream at a particular time? If it’s in the entire stream, that’s not much help. However, if it is at the very beginning, you can suspect that the infection is fairly far down in the urinary tract, so that it gets washed out early in urination. (You’d be less likely to suspect kidney involvement in this case.) If you see blood only at the very end of the stream, you can suspect that the bleeding is in the bladder, pooling at the bottom of the bladder and therefore not getting out until very late in urination. (Here again, the kidneys may be safe.)

Of course, there are lots of other tests that get done, but I like the simplicity of this part of the equation. As always, please do not use information you find here to diagnose your dog! If your dog is peeing blood, or even just peeing more often than normal, your dog needs to see a veterinarian.

This week’s test: Small animal medicine/surgery. Why do they always schedule tests in the two most demanding classes right next to each other? This exam is mostly renal stuff (kidney disease, urinary tract infections, uroliths) and endocrine stuff (Addison’s, Cushing’s, hyperthyroidism, hypothyroidism, diabetes).

Wednesday, October 27, 2010

Veterinary fact of the day: castrating lambs

I am plowing through flash cards for my upcoming large animal medicine/surgery exam. Current favorite card:

Q: Best time to castrate a lamb?

A: First 12 hours of life, after that too hard to catch

So descriptive in its brevity.

Tuesday, October 26, 2010

Canine obstetrics

We had our canine obstetrics lecture recently. After learning about equine obstetrics and bovine obstetrics, I was really glad to get a chance to hear about dogs. Our lecturer was Dr. George, who is an emergency and critical care (ECC) specialist who has particular knowledge of this subject area because he is also a dog breeder.

So you’re an ER vet, and an owner brings her bitch in. The bitch was in stage II (active) labor for an hour, produced one puppy, had contractions for three more hours, and now has stopped having contractions. What do you do?

Your two choices are to perform an immediate C-section, or to give oxytocin to get the contractions restarted. There is no downside to the C-section; it is very safe for mom, and definitely the safest course for the puppies. However, it is very expensive. The oxytocin route is much less expensive, but it may result in some dead puppies, and if it doesn’t work you’ll end up having to do a C-section anyways. Dr. George noted that the most frustrating case is the one in which you give oxytocin and manage to get all but one puppy out, and after five hours of letting her push puppies you finally have to give up and do the C-section after all. So what issues do you take into account when you’re working through these options with the owner?

First, how many more puppies do you expect? Sometimes owners have had radiographs (x-rays) taken and know the minimum number that are in there. (Of course, sometimes puppies hide on radiographs — Dr. George doesn’t know where — and you are likely to get more than you expect.) If you expect a lot more, do the C-section, because you’re fairly likely to end up having to go that route anyways. If you only expect one or two, oxytocin might be a better option.

Second, what are the owner’s constraints and expectations? Dr. George says he gets two kinds of obstetrics emergencies: the chihuahua from the streets of Worcester (i.e., a dog from a low-income area), and the golden retriever from Westborough (i.e., a dog from a high-income area). In the case of the golden from Westborough, the owners are likely to be willing to pay quite a bit to ensure the safety of the puppies, so the C-section is the best option. In the case of the chihuahua from Worcester, the owners may just not have the money, and may not have planned the pregnancy anyways. In that case, go with the oxytocin; the puppies may not survive, but if the alternative is euthanasia because the owners can’t afford the C-section, you’re still doing some good. Dr. George says he will be very frank with owners, asking them to tell him their goals up front. Are we just trying to save mom, or are we doing everything we can for everybody?

I have been really enjoying the canine theriogenology (breeding and obstetrics) section. I’m considering doing some elective time during my clinical months at a practice that specializes in this stuff. What better way to learn more about dog breeds and their genetic problems?

This week’s exam: Our test this Friday is our second Large Animal Medicine and Surgery exam. Cows, cows, cows! After this we are done with cows; the rest of that course will focus on horses. That will be very different, as horse owners’ goals tend to be very different from cow owners’ goals. However, this test looks like a rough one, so I am head-down studying this week.

Sunday, October 24, 2010

The joys of scheduling 82 students over 12 months

As my class nears the beginning of our clinical time (in only 147 days!), my school has to schedule us. For the first three years of vet school, cohorts do almost everything together. A few hours a week are set aside for individual activities, but mostly you show up, sit in a big lecture hall with 81 of your closest friends, and listen while one faculty member after another shows up and talks at you.

Obviously, 82 of us would not fit in the tiny cardiology room or the ER all at once. So for our 12 months of on-campus core rotations, we are split up into little groups. (The final two and a half months of clinical time is all elective time and expected to be mostly off campus.) I do not envy the administrator who has to manage these schedules! We all have requirements (I need a specific week off for my brother’s wedding on the other side of the country; a friend of mine needs a specific six weeks for an elective at a nearby aquarium). And we all have preferences (mostly we want our Ambulatory rotation, which is outdoors in Connecticut, to be in September and not in February).

The scheduling is done in two stages. For the first stage, we are each assigned the order of our major blocks. What’s a major block? Basically, the 12 months is split into four seasons. You do a group of rotations together over the course of three months (one season); that is a major block. So I might do one set of courses in the spring, and someone else might do that same set in the fall.

We were all in lecture when email came from administration that our scheduled block information was now ready and in our mailboxes. Because we all have laptops in lecture we all knew immediately. There was 30 minutes of lecture left. The tension was palpable. One student actually got up and brazenly left lecture, to return with her envelope (and the envelopes belonging to her friends sitting near her). I jiggled all through the next 30 minutes until we had our break and could get our schedules. I am afraid the subsequent lecture was shot as well, as we were all obsessed with our little pieces of paper throughout it.

I mostly but not entirely got the order that I wanted. I will not be doing Ambulatory in the winter. LPK will. I am concerned that she may not survive. I was at that clinic for one day in January for a second-year rotation day, and it almost did me in. “Now we will vaccinate these three dozen calves. You are all going to have to take your gloves off to handle the syringes.”

In a week we will go through a second lottery process to establish the order of the individual rotations within each major block. (Small animal medicine first? Or pathology first?) This is a full day process; we have no lecture scheduled that day and are expected to spend the entire day in the administration building, waiting for each pass through the lottery. (Four blocks, plus two weeks of required on campus electives, means six passes through the lottery.)

And then my schedule for 12 months of my life will be set. If any friends of mine choose to get married and ask me to attend, I may have no way to get time off. (I told my brother that he had to decide on a day for his wedding before the lottery process began, so I could adjust my schedule around it, more than a year ahead of time.) It’s going to be a very different life from the one I am living now.

Saturday, October 23, 2010

Links post


Wednesday, October 20, 2010

Number Needed to Ban: a new tool for calculating the benefits of banning particular dog breeds

A study published this month in the Journal of the American Veterinary Association (JAVMA) takes on the issue of whether breed-specific legislation (BSL) is effective. BSL is a tool used by some communities to attempt to reduce injuries from dog bites. The idea is that particular breeds of dogs are responsible for more than their share of injuries, so banning or otherwise controlling those breeds will result in a reduction in injuries. The group of breeds collectively known as “pit bulls” receive the most attention today, though other breeds (Rottweilers, Dobermans, German Shepherds) have received attention in the past.

But does BSL actually work? Experts say no; how the dog is trained and managed is a better predictor of aggression than its breed. Nevertheless, new BSL continues to be enacted. So why do legislators reach for this tool?
The authors of “Use of a number-needed-to-ban calculation to illustrate limitations of breed-specific legislation in increasing the risk of dog bite-related injury” believe that BSL’s appeal comes from:

  • Misperception of risk. Poor reporting of the number of dog bites that occur and of their severity makes it very difficult for the public to get a handle on how often they occur.
  • Stereotyping and misinformation. The media may portray particular breeds as especially aggressive, in the face of scientific studies which suggest that they are not.
  • Erroneous beliefs about efficacy of BSL. There is currently no evidence for the effectiveness of BSL, but  there is evidence to suggest that it is ineffective.
The authors hope to provide a tool for use in understanding the effectiveness of BSL, and they hijack some terminology from the medical community to do so. “Number needed to treat” (NNT) is a concept used to understand the effectiveness of a particular medication or therapy. For example, you have a patient showing signs of a stroke. Should you give him tPA (tissue plasminogen activator)? One measure you might use in making this decision is NNT. How many similar patients would you treat with tPA, on average, before you saw one patient improve? A smaller NNT implies a more effective therapy. In human medicine, we expect the NNT of an effective therapy to be in the tens or at most hundreds.

The authors suggested evaluating BSL’s effectiveness using a “number needed to ban” (NNB) concept. If BSL is implemented in a particular community, how many dogs will need to be banned (removed from the community) before one dog bite (or dog bite related injury, or dog bite related fatality) is prevented?

The authors point out that because our knowledge of the true prevalence of dog bites is so poor (many are never reported), this calculation is hard to do. I think the important thing to understand is that what they are offering is a tool that can be applied to different statistics. After all, dog bite prevalence will vary among different communities. This tool can be used to understand the possible benefit of BSL in different communities. It’s an algorithm to apply to a variety of data inputs!

However, the paper would have been really unsatisfying without some numbers, so they applied their algorithm to some statistics (much appreciated, because I hate arithmetic).

  • Based on the reported number of dog bite related emergency department visits, 5,128 dogs would have to be banned to prevent a single emergency department visit in one year.
  • In Kansas City, 4,255 dogs would have to be banned to prevent a single emergency department visit in one year.
  • 30,663 dogs would need to be banned to prevent a single reconstructive surgery in one year.
  • 109,495 dogs would need to be banned to prevent a single hospitalization in one year.
  • 59,523 dogs would need to be banned to prevent a single insurance claim in one year.
The authors note that these calculations were based on legislation banning a particular breed or breeds entirely. For legislation which simply requires that dogs of a particular breed(s) be muzzled while in public, these numbers would be even higher, because such legislation would not prevent bites on private property (which is where many of them occur).

It is the authors’ hope that “easily understood communication tools, such as NNB, can help put the lack of efficacy of BSL into perspective and narrow the perception gap.” This is a great tool and I hope we see it used more. I am concerned that proponents of BSL will argue that any tool is only as good as the data put in to it, and that the lack of reliable reporting of dog bites will mean that this tool isn’t itself reliable. However, as long as we are focusing on enacting BSL instead of focusing on understanding the true problem, our data will continue to be flawed. This article represents a step forward in understanding data about the causes of dog bites. Our next step is improving the accuracy of that data.

Patronek GJ, Slater M, & Marder A (2010). Use of a number-needed-to-ban calculation to illustrate limitations of breed-specific legislation in decreasing the risk of dog bite-related injury. Journal of the American Veterinary Medical Association, 237 (7), 788-92 PMID: 20919843

Tuesday, October 19, 2010

On becoming a vet student: career changes

A few weeks ago, I was in line for free food before a lunchtime talk, and I overheard the woman in line behind me saying “Yeah, I wish I could go to school here, but it’s kind of late now.” Because I am no good at keeping my mouth shut, I turned around and told her, “I did that. I was a medievalist in college and an online publishing programmer for twelve years after that, and then I went to vet school. I had to go back and take all my basic science prerequisites, so it took me two and a half years of night classes before I could apply. But here I am.” She was intrigued and asked for my email address, but today I realized I never heard from her. So I figured this would make a good blog post for anyone out there who is thinking it’s too late to become a vet.

How did it work? Vet schools tend to require more pre-requisites than medical schools. The basic sciences that everyone has to take to apply to one of these programs are: two semesters of inorganic chemistry; two semesters of organic chemistry; two semesters of biology; two semesters of physics; two semesters of mathematics. The schools I were interested in also required a semester of biochemistry and a semester of genetics, although my biology class had enough genetics in it that I got that requirement waived. It is my understanding that medical schools don’t require the biochemistry and genetics, although they do require that you pass the GMAT, which is a much harder test than the one I had to take, the GRE.

There are plenty of extension schools out there which let post-baccelaureate (post-college) students take classes of all sorts. There are lots of people who go back to do pre-med programs, or finish up the last of their pre-med requirements after college graduation. At age 31, I was on the older side, but there were a few other students in my age bracket. It is definitely tough to afford your mortgage when you are working part-time in order to take two classes at once and get your volunteer experience in, but I was in a hurry to get through the pre-reqs. I could certainly have done fewer at a time and had more time to work; my friend LPK worked full time and took only one class a semester. It is, of course, easier if you have a partner who will support you while you go to school, but I am proof that you can do it while single.

I'd like to put in a particular plug for Harvard Extension School, here, for anyone in the area. That was a very well organized program for post-bac students. Classes were held in the evenings, just once or twice a week (longer at a time, of course). This structure was convenient for people like me who were trying to work during the day. I also took some classes at a school which just dumped me in with the undergraduates. This was socially awkward, of course, but additionally, their schedules meshed poorly with mine. Classes met three times a week, during the day, so that I had to take time off work, and commute much more often. They have intensive classes over the summer; I completed a year’s worth of physics in just seven weeks (I am a “pull the Band-Aid off fast” type of girl). Of course, I did not work during those seven weeks!

I started with inorganic chemistry, and it was overwhelming for someone who had basically never been really introduced to hard science before. (As an undergrad I took a history of astronomy class and an evolutionary biology class to satisfy my requirements. The biology class was responsible for the lowest grade on my college transcript.) I have since heard of The Cartoon Guide to Chemistry, which I really wish I had read before taking that class. It would have been a gentler introduction. I remember being bewildered at this substance, NaCl, which apparently liked to split into Na+ and Cl- — no one ever explained to me why it did that. I was coming from the land of complete ignorance of chemistry and it was a rough transition.

One of my semesters of math was biostatistics. I took it at the graduate level, and was as a result actually able to place out of biostats in my second year of vet school. I am so glad that I did that.

One thing that I figured out for myself, and wish to suggest to other people, is: you can take electives during your pre-vet time, even if you are taking night classes. Electives fit in well in your final semester, after you have completed most of your pre-reqs and your application is pending. I took some classes which I thought would be helpful for my planned career in animal behavior (neurobiology and psychology). I also took one class because I didn’t know if I would ever have the chance to take a class like that again. (The Cognitive Dog. This class is still on offer and can be taken remotely, so you don’t have to live in the Boston area to take it. I highly recommend it for anyone interested in dog cognition. It was just fascinating. It requires no science background at all, though it should not annoy people who do have a science background.)

In addition to academic pre-requisites, veterinary schools require that you have some hands-on experience with animals, particularly of a medical nature. It is nice for this experience to be varied. I found that shelters are eager for volunteers; find a shelter of a large enough size to have a vet on staff, and make it clear that you are interested in shadowing the vet, not just cleaning cages. Some shelters have large animals, as well; getting large animal experience can be difficult. I also simply approached some veterinarians and asked if I could regularly shadow them. The worst they can say is no.

One of the best volunteer experiences I had was at the wildlife clinic at the vet school that was my first choice (and where I am now enrolled). I was not specially interested in wildlife, but I got to interact with students and see what life was like on campus. That was invaluable. If you have a vet school near you, I recommend you call them up and ask to speak to their volunteer coordinator, who can help you find something.

It is never too late to make this career change. My school recently graduated someone who is in her fifties. If you want it enough, the resources are there to help you do it. I am always happy to answer questions from people who are considering becoming veterinarians but not sure how to start. It is doable!

Monday, October 18, 2010

So how can we make things better for dairy cows?

Recently we had a lecture from Dr. Gray on production medicine. Before I explain what production medicine is, let me give you a feel for what Dr. Gray is like. He is probably the member of our food animal faculty with whom I agree the most about food animal welfare, although we certainly don’t see completely eye to eye. He is a hugely amusing lecturer due to his propensity to tell involved stories about something that happened on the job recently, and to write random bits of them on the whiteboard.

This particular whiteboard was such a work of art that I convinced my classmate LPS to photograph half of it, at risk of looking like a nerd in front of the class. You will note that, at one point, Dr. Gray was telling how he had made a plan with a client to meet on a particular date, and he wrote the date on the board. (I was tempted to raise my hand to ask if that would be on the test, but since I had sassed him twice in lecture on the previous day, I decided everyone would be happiest if I kept my mouth shut.) Another friend, LPK, at one point noted that Dr. Gray had erased three milk production curves from the previous day in order to draw a fourth. These were generic milk production curves, i.e., “She makes less, then she makes more, then she makes less.” He could have simply pointed to one of the previous ones. Here, in all its glory, is half of the whiteboard:

(Thanks, LPS! Also: the “countdown to clinics” is maintained by my class, not Dr. Gray. That’s a real count; I will be playing doctor in less than 171 days.)

Dr. Gray explained what production medicine is by telling a story. He was in the truck, driving to lecture a bunch of third year students, when he got a call from the manager of a farm. The owner of the farm had set some financial goals for the farm; he wanted to see them sell 75,000 lbs of milk a day. Since they were currently selling 61,000 lbs, the manager had a problem, and he was calling Dr. Gray to talk about it.

Now, if you are a dairy farmer and you want to sell more milk, you have two ways of doing it. You can milk more cows, or you can get more milk from the cows you already have. Buying or raising more cows involves some overhead costs: if you get too many more, you need to build a new barn. If you try to cram too many into the barns that you already have, they will not do well, and the result will be decreased milk production. This farm manager wanted to convince the cows he had to give him some more milk, and maybe figure out if it was safe to keep a few more cows as well.

There are a lot of factors to take into account in this game. How many cows can you fit? If you have too many, they will all be waiting in line for a long time at the milking parlor. This will eat into their daily quota of lying around chewing their cuds, which will mean poorer quality digestion and less milk. How much milk will each cow produce? This has a lot to do with what she eats. Is she eating as much as you want her to, or is something preventing her from doing so (too many cows at the feed bunk)? Is there a way you can change her diet to provide more energy for her to turn in to milk? If you provide too much energy, her rumen will acidify. At low levels (“sub-clinical rumenal acidosis”) she won’t look sick, but her life expectancy will be shortened, and, you guessed it, she will make less milk. At higher levels, she can have ulcers which eat their way through the wall of her rumen and seed her bloodstream with bacteria. The bacteria make it to her lungs, where they generate clots. And that can kill her in a fairly unpleasant manner.

Production medicine is all about balance. More of a particular factor will give me more milk until it starts giving me less milk. To some extent, the welfare of the cow is in sync with the welfare of the farmer’s bank account. A sick cow doesn’t give as much milk as a healthy one. But to a very large extent, this relationship does not hold true. It often makes more financial sense to sacrifice optimal cow health (accepting sub-clinical rumenal acidosis in many cows in your herd) in the name of income (increased milk production in the remaining cows due to high energy feed). At other times, farmers simply can’t afford veterinary care for every cow that needs it when she might need it.

So do I think dairy farmers are jerks who don’t care about their cows? I absolutely do not. I have a lot of sympathy for their situation, and the ones I have met have been really nice guys who clearly do like their cows. But, to give an example of a population of humans that we all know care about animals — people who love their dogs make bad management choices when they are in bad situations. And dairy farmers are, many of them, in bad situations.

I believe that if they could afford to, more farmers would have smaller farms, with more personal care of their cows, with more cows out on grass. And I believe that almost none of them would skimp on veterinary care if they could afford to give their cows the care they want. But dairy farmers are suffering from very low milk prices right now. They do not have enough income to have the luxury of doing the right thing. They are just trying to get by. They are driven to making bad choices, like packing too many cows into a barn, or sacrificing veterinary care.

Mostly, the small farmers are driven out of business, and the large farmers are taking over, because that makes more financial sense. Dr. Gray reports that a 5,000 cow dairy is the most efficient one. Are large farms worse? Well, if they are more profitable, the cows are likely to get better nutrition and better veterinary care. Other things will be better for them too — the concrete that almost all dairy cows live on will be covered in better bedding, for example.

But in my opinion, the very best farm is the small farm with enough money. On that farm, there are few enough cows that they can be put out on grass sometimes. (Imagine getting 5,000 cows out onto grass, and then onto the next pasture segment a few days later, and then onto the next pasture segment a few days after that, not to mention getting them all to the milking machine at least twice a day.) It is a farm where the farmer can know each of his cows, and notice right away when one of them is not quite right, so that she can receive medical attention promptly. It is a farm where the number of cows is small enough that infectious disease is not a big problem. Are there any farms like this left? Vanishingly few, if any. Dr. Gray opined that the big farm is the farm of the future. The small farm is on its death bed.

I raised my hand and asked Dr. Gray if he thought there was anything veterinarians could to affect this situation, to try to fight against the death of the small farm, or otherwise take steps to change the situation of dairy cows. He replied, “No.” In his opinion, no one really cares all that much about cows. There are some people who do, like a lot of the students in the class, but he suggested that we were the exception, when you look at society as a whole.

The lecture moved on, but I wasn’t done. During the break, I talked to Dr. Gray more, along with Daria, a classmate of mine who has worked on farms and is interested in food animal medicine and herd health. I pointed out that people do care about food animals; they voted “yes” on Prop 2 in California, knowing that it would almost certainly raise food prices. Daria added that consumers do have power to affect farm animal practices; there is almost no milk sold in the Northeast from cows that were given rBST (a synthetic growth hormone), and that is because there was no demand for that milk from consumers.

Dr. Gray protested that neither of those things were useful things to do. Proposition 2 enacted rules with no science behind them and may not actually make things better for animals. And science shows that rBST isn’t bad for cows or people. (I’m not going to get into whether I agree with either of those statements; they are his viewpoint.)

I replied that the point is that consumers have power. What they are lacking is information. I noted that I have always purchased organic milk in grocery stores. Until I started vet school, I was under the misapprehension that this would lead to at least somewhat improved welfare for the cows in question. I now realize that that is not true. But I have always been willing to spend more money to purchase a better life for the cow whose milk I drink. I believe that other people agree with me.

The problem is that people don’t know how to vote with their pocketbooks for a good life for cows. They don’t necessarily know whether or not dairy cows have a good life. (My opinion: it is not by any means torture. But it is unpleasant enough that since taking this class I have stopped buying milk in the grocery store.) So my answer to the question “what can veterinarians do?” is this: veterinarians can educate.

What can you do? Unfortunately, there isn’t a good answer to this question.

  • Buy organic milk at the grocery store? This will probably not make any contribution to dairy cow welfare. Farmers who produce organic milk have an incentive to not treat sick cows, because once a cow has had any antibiotics at all, her milk is no longer considered organic, and will bring a lower price. Regulations about what is organic make no specifications about humane handling of cows.
  • Buy less milk? I certainly think that Americans consume too much milk (mostly in the form of cheese). But buying less milk right now is probably going to have the immediate effect of driving more small farmers out of business, which is not the best thing from a dairy cow’s welfare standpoint.
  • Buy milk from farms with grass-fed cows. This is what I am trying to do, but it is awfully hard to find farms like this! I have failed to find milk from grass-fed cows in my area, but my farmer’s market does provide me with cheese and yogurt made from milk from grass-fed cows. Check out your local farmer’s market. Does your town lack a farmer’s market? Maybe you can start one. The market in my town was started by one guy with a lot of enthusiasm a few years ago. Does your town’s farmer’s market not have milk, cheese, or yogurt from grass-fed cows? Let the organizers know that you’d like it to. Or maybe you can set up a buying co-op. Think out of the box.
This is a hard question and I don’t see a good solution in sight. How can consumers support particular farms when grocery stores provide them with food that has passed through so many middle-men that there is no way of knowing exactly who they are supporting? Hopefully farmer’s markets will continue to flourish and will start providing a usable mechanism for consumers to connect directly with the source of their food, so that they can more easily evaluate the welfare of the animals whose owners they are supporting. For now, I leave you with a photograph of the farm where the cows live who produce the milk in the yogurt and cheese I have been buying lately:

Sunday, October 17, 2010

Why veterinary anesthesia is a thrill a minute

Last week I had my anesthesia and analgesia final exam. Some people seem to think that anesthesia is boring. (The Amateur Transplants refute that fallacy pretty well.) Anesthesia is in fact pretty complicated. I sort of wished that the choices you have to make for each anesthesia case could be written out in a huge decision tree, but I didn’t have the energy to do it myself. Roughly, here’s how it goes.


First, you might want to make the animal sleepy so it doesn’t try to bite you, kick you, or run away from you. The choice of sedative or tranquilizer here is dependent on a lot of factors. How old or young is the animal? (Foals may not need any premedication at all.) How sick is it? (Healthy animals benefit from different premedications than critically ill ones.) Does it have heart disease? (Many sedative/anesthetic drugs depress the function of heart muscle and could kill an animal with heart disease.) And, of course, what species is it? For this exam, we learned details about the kinds of drugs that were best for dogs, cats, horses, goats, sheep, cows, llamas, and alpcas. We did a whirlwind tour of issues in rabbits, ferrets, rats and mice, birds, lizards, and snakes.


Once the animal is premedicated and drowsy (or if it is naturally unlikely to protest), the next step is to induce anesthesia. Many of the same questions of drugs come up, and many of the same drugs are used for this stage of the process, just in different amounts or given by different methods. It is nice to have the animal mellow for this stage, because commonly the next set of drugs is given intravenously. It is best to put in an IV catheter to do this. A catheter allows easy access later. This is useful to give more induction agent, as they are sometimes given in bursts; to give a reversal agent if necessary, which you may have to do in a hurry if there are problems; or to give other drugs while the animal is anesthetized, such as antibiotics or pain medication, without having to find a vein again.


Once anesthesia has been induced, it has to be maintained. You don’t just knock an animal out and hope it stays out for as long as you need — well, actually, sometimes you do. The question is how long you need to keep the animal under, how painful the procedure is going to be, and sometimes whether you have the equipment for your preferred maintenance method. If you are in the field with a horse that can’t be brought in to a hospital, you will probably not choose to intubate the horse and maintain it with an inhalant anesthetic. For a short procedure, one dose of injected anesthetic might be sufficient, or anesthesia could be maintained by an IV drip. On the other hand, for most surgeries on dogs in a  veterinary hospital you will choose to employ an inhalant anesthetic.

How are you going to get the inhalant gas into the animal? Most commonly you will intubate (put a tube down the animal’s throat). In some cases, you will not be able to do that, and will put a mask on the animal’s face instead. We don’t like masks because they are liable to leak and you don’t want anyone but the animal to be getting that gas — the veterinarian would be breathing small amounts of anesthetic gas during every surgery, which is not a good thing. But sometimes intubation isn’t possible, particularly for very small animals. Interestingly, we were taught that you do intubate snakes, and that in fact you do so before inducing anesthesia — you sedate them and then put the tube in while they are still awake.

Recovery and post-operative analgesia

When the animal wakes up, there are another host of questions. Some animals are more liable to regurgitate than others. Regurgitation is a Bad Thing (it can lead to inhaled stomach contents and aspiration pneumonia, which may be fatal), and so extubation may be done using different techniques to avoid it, depending on the species.

Post-operative pain control is also extremely varied among species. As a general rule of thumb, you go for NSAIDs in horses and cows, but opioids in dogs and cats. Opioids can reduce gut motility, which is bad in animals with big complicated stomachs like horses and cows. (However, we do still use them in those animals.) On the other hand, NSAIDs can cause kidney issues in dogs and cats, while horses and cows handle those drugs really well.

NSAIDs are particularly interesting in veterinary medicine. In human medicine, there was an attempt to find COX2-selective NSAIDs, which would inhibit only the COX2 form of the enzyme (which is involved in pain) and not the COX1 form (which is essential to normal stomach wall function, among other things), in the hopes of finding NSAIDs which handled pain without causing stomach ulcers. Unfortunately, COX2-selective NSAIDs have turned out to be problematic in human medicine, causing an increased risk for heart attack, among other things. These side effects have not manifested in veterinary patients on COX2-selective NSAIDs, however, and most of the NSAIDs that we give dogs are COX2-selective. Interestingly, the COX2 selectivity of any particular NSAID is different in different species. In other words, a drug that selectively inhibits COX2 in a dog may inhibit COX1 and COX2 equally in a human.

Which leads me to my public service announcement of the day: acetaminophen (Tylenol) can kill a cat, and ibuprofen (Advil) can destroy a dog’s kidneys. Always ask your veterinarian before giving your pet any form of pain relief. There’s lots out there for them, but the exact drugs that are appropriate differ hugely between species.

Saturday, October 16, 2010

Goodbye rinderpest

The UN announced this week that the rinderpest virus has been eradicated. Rinderpest kills — oh wait, killed — cattle in Asia and Africa. I learned about it in microbiology during second year.

This is a really good example of One Health in action. Eradicating rinderpest was a huge undertaking. Complete eradication of a virus has only happened once before, with smallpox. So did we take this on just out of sympathy for sick cattle? No, this effort was prioritized because of the humans whose livelihoods (and dinners) depended on their livestock. To have healthy humans, you need healthy animals. That’s the essence of One Health — veterinarians and human doctors working together.

I would like to point out how heavily veterinarians were involved in this process. They helped identify the disease, develop a vaccine, test the vaccine, and they certainly were out there getting their hands dirty making sure the vaccine was in use (getting it to the people who needed it and educating those people about why they needed it).

[ETA: See a really interesting history of the development of the rinderpest vaccine at Speaking of Research (as noted in the comments on this post).]

Wednesday, October 13, 2010

Veterinarians accused of predatory lending

Really interesting article in VIN News: Health credit programs: safety net or predatory lending? Apparently the New York State Attorney General’s Office is investigating CareCredit, alleging that it “preys on seniors and vulnerable patients.” CareCredit is used at my school’s veterinary hospital, and many others, to provide on-the-spot credit for people who can’t pay their veterinary bills but do want to find a way to afford a procedure. (The alternative in many, I’m guessing most, cases is euthanasia of the pet.) 

I think CareCredit is really important; without it, people who aren’t prepared for how high veterinary medical expenses can be these days would have to euthanize their pets instead of getting treatment. The New York State Attorney General's Office reports the following consumer complaints (it is not clear how many of the providers involved were veterinarians): 

Health care providers misled them that CareCredit comes interest-free when in fact interest is charged when balances aren’t paid off following a promotional period of six to 18 months.

I wonder how many of these people were told of the card’s terms but failed to absorb them due to the emotional overload that can happen when your animal is in the ER and extremely sick. It does sound like veterinarians need to be a lot more careful in explaining those terms.

Services proposed but never performed were charged to CareCredit accounts, and account holders were unable to obtain refunds.

That is upsetting. I don’t think it’s a problem with CareCredit, though. I think it’s a problem with individual practitioners.

Medical offices pressed clients to use CareCredit even when clients had the cash to pay.

Both upsetting and a potential problem with CareCredit; I’ll be curious to see where this part of the investigation goes. More specifics would be nice, too. Since CareCredit is interest-free for some period of time, it may actually be in a customer’s best interest to use it, if they are sure they can pay it down promptly.

In general, I would hope to see legal consequences for practitioners who behaved illegally or unethically. I would hope not to see consequences for CareCredit if the only problem is with individual practitioners.

The article goes on to quote Jeff Stillinger, a practice management consultant and Certified Veterinary Assistant:

“We in the industry have failed miserably with reminding the client they need to budget and save... I have never once been handed, or handed out, a puppy/kitten package that contains such information. We don’t have to go overboard and do it for them, or teach them how. That’s not our responsibility. We simply need to remind them it needs to be done.”

I agree. I think veterinary culture emphasizes stepping back, letting the client make their own decisions, which is good — but when that is at the expense of failing to educate, it is bad. People have no way of knowing when they buy a puppy that a visit to the ER after a bad car accident could cost thousands of dollars. It’s our job to prepare them for that.

Tuesday, October 12, 2010

How to learn how to spay a dog, addendum: uterus removal

Today I took a uterus out of a dog! As you may remember, when I did my spay lab, my dog unexpectedly arrived pre-spayed. I expected to have to repeat the entire lab, but it turned out that a member of my class, Minerva, couldn’t remove her spay dog’s uterus for religious reasons. We asked the course head if I could take out the uterus for Minerva, while she would do the rest of the surgery (basically opening and closing the dog). The course head agreed, so it was a go.

I showed up at a decadent 8 am. The spay lab students already had been in the clinic for two hours; the dogs had received their premedication, anesthesia had been induced, and they were on the tables, already clipped, scrubbed, and draped. It was a little disconcerting to meet this dog, whose uterus I was going to remove, as just a bare belly under a window in the drapes. I can’t even tell you for sure what color her fur was.

Minerva made the incision and found the uterus. I confess to a moment of nervousness: maybe I was cursed. Maybe this dog would also be uterus-free. (Minerva noted that the dog had apparently had puppies recently, so this seemed unlikely.) And then came time for the uterus removal.

Dog uteruses are a little different from the human variety; they are Y-shaped, with a small body and two long uterine horns, where the puppies would grow. (I don’t know why it is adaptive for them to have such a different uterine shape. I don’t think it has to do with number of offspring in a litter, because horses have twins no more often than humans do, but their uteruses also have long horns, just like cows, cats, sheep, and goats.)

So what Minerva found was the left uterine horn, with the ovary at the end. At that end, the whole structure attaches to the body wall in two places. The suspensory ligament is a small ligament running from near the ovary to the body wall; it can just be broken manually, no big deal. Then the pedicle connects the uterine horn to the body wall more extensively.

The pedicle is the bit that is harder to separate. First it must be clamped twice, using carmault forceps, which are long curved forceps which I am told are special for spays. Then you double ligate the pedicle — tie it off twice so that when you cut, it does not bleed. I placed a loop of suture material around one clamp, removed the clamp, tightened the suture very very tight, and made a very secure knot. (Knot tying was a skill we had to learn before being allowed in the door.)

I did the same for the second suture, but for that one, I just moved the clamp up a little, so that I had a clamp to cut against. I made sure to have hold of the pedicle with a smaller forceps, below the ligatures, so that when it was cut it wouldn’t jump back into the abdomen before I had a chance to look at it. Then I cut above my ligatures. I looked carefully at the stump: any extra bleeding? No, it looked good. So I let go of it and watched as it fell back into the abdomen. Now one horn of the uterus was free.

I did the same thing on the other side. The right side is a little harder. All the organs on the left side are pushed down a little towards the dog’s tail to make room for the heart, which means that the uterine horn is a little easier to get hold of on that side. On the right side, the horn was closer to the dog’s head (“more cranial”). I cut it away, and now the entire uterus could be pulled out of the abdomen (“exteriorized”). Minerva and I looked carefully to make sure nothing had come out with it that needed to stay in.

Finally, the uterus is (obviously) attached at the tail (“caudal”) end of the dog — where the babies come out! I double clamped the uterine body above the cervix, and tied it off twice. I cut and inspected and released. And then the dog was spayed.

At that point I stepped back and let Minerva take over. I wrote up a detailed surgery report, using somewhat different words than I have used here, and then I was done, even with some free time before my lunch meeting to do things like write this up. It feels so good to have actually taken out a uterus! (If you'd asked me a few years ago if I'd ever write that sentence, I would have thought you were insane.)

[How to learn how to spay a dog, part 1: Basic skills]
[How to learn how to spay a dog, part 2: Anesthesia]
[How to learn how to spay a dog, part 3: Surgery

Sunday, October 10, 2010

Links post

Meta science blogging

Saturday, October 9, 2010

Veterinary terminology: signs and symptoms

Way back in my first year of vet school, faculty were very concerned with teaching us the basics of how to talk like vets. One of the first pieces of terminology that was explained to us was that animals don’t often have “symptoms”; they have “signs.” A symptom is something that you report. “I’m feeling nauseated.” A sign is something that someone else observes: “My dog vomited three times yesterday.” I guess Kanzi could have symptoms, but I expect all my patients to have signs.

What I did yesterday: Theriogenology midterm (cow sex, sheep/goat sex, horse sex. That class had lots of amusing photos in the powerpoints, but I didn’t feel right stealing any of them to show you guys. I considered googling for interesting replacements, but just in time realized my mistake before making a web search that I would have really regretted). Got out early enough to go to the gym. Two hours of dermatology lecture. Spent lunch running home to pick up my laptop’s power cord (oops). Two hours of anesthesia case studies (our anesthesia final is next week). One hour of large animal medicine/surgery: how milking machines work.

Tuesday, October 5, 2010

Shades of grey in the ethics of animal research

This afternoon I read Animal Research: Animal Welfare vs. Animal Rights, by Walter Jessen of Highlight Health. The article addressed some myths about animal research, explaining why it is necessary and what we do to maintain the health of research animals. In many ways, it was a typical volley in the debate between scientists and animal rightists about animal research.

I have issues with the arguments used by both sides of this debate, which miss a lot of shades of gray in the question about whether it is wrong to perform research on animals. The article ably addressed some of the myths and mis-framings presented by the animal rights side of the debate. That is important communication to provide. However, it introduced some mis-framings of its own, and I’d like to address those here, while recognizing that the article is completely factually correct.

Animal rights vs. animal welfare

Jessen starts by defining his terms (“animal rights” and “animal welfare”). He chooses the most extreme position for animal rightists, describing them as people who “reject eating any animal as food, abstain from taking any over-the-counter drug and/or prescription medication, and refuse all vaccinations and/or medical treatment.”

In my experience, that description characterizes a truly extreme group. It leaves out those who take a more graded approach, such as a belief that animals shouldn’t be eaten, but may be used in some forms of research. This may be an attempt to frame the argument in terms of scientists versus fringe crazies. What about the people who fit in neither camp? Isn’t that where most of us lie, accepting medical treatments but feeling somewhat uncomfortable about animal research? Can’t scientists address that discomfort without resorting to the suggestion that anyone who feels that animal research may be wrong must reject all medical treatment?

Immoral and necessary

Jessen argues that animal research is necessary because “animal systems provide invaluable and irreplaceable insights into human systems.” That is completely true (and I would add that animal research provides invaluable and irreplaceable insights into animal systems as well. It isn’t only useful in human medicine). Jessen doesn’t go so far as to say that because animal research is necessary, choosing to perform it is also moral. But that seems to me to be the point of his article: we don’t need to feel bad about this; this is necessary. But just because something is necessary doesn’t mean we should be completely comfortable with it. Can’t animal research be both necessary and immoral? Can’t we choose as a society to do it without absolving ourselves from feeling disturbed by it? When we read about an interesting experiment that involved animal research, can’t we think how cool the results are and how we feel sorry for the animals?

A mountain climber is stranded in a snowstorm. Help won’t come for days. His companion dies. Our hero eats his friend so that he won’t starve to death himself. Immoral, but necessary. He does it, and he knows it is the right choice. But he feels terrible about doing it. Perhaps he will take care to provide for his companion’s children.

A single mother in a country that does not have welfare loses her job through no fault of her own. Her savings are gone. She loses her home. Living on the street, she steals food to give her children. She knows it is wrong, and she feels bad about it. But she also knows it’s the right choice.

Recently I had elective surgery. After the surgery, I chose to use painkillers that surely had been tested on animals. I know that animal research is wrong, and I feel bad about it. But I also know that it is the right choice to continue to learn about how to keep humans and animals healthy.

The debate about animal research is often presented as two choices: it’s wrong, and we should never do it; or it is necessary, so we shouldn’t feel bad about it. We should feel bad about it. And we should continue to do it. (But we should do it somewhat differently than we do now. Read on.)

Are research animals comfortable?

Jessen writes that  “the vast majority of biomedical research does not result in significant discomfort or distress to research animals.” I think he is addressing the misconception that research animals spend the majority of their lives in a great deal of pain, and wants to make the point that they are kept mostly pain-free. However, he writes that “57 percent of all research procedures with animals involved no more than slight or momentary pain or distress.” I note that that leaves 43 percent of procedures that do involve more than momentary pain or distress. That’s a significant fraction.

He also writes that “thirty-eight percent of the research procedures employed anesthesia and post- operative painkillers.” I should hope that painkillers were employed where indicated! But I also would like to point out that painkillers don’t remove all the pain. Would you choose to undergo an unnecessary surgery if you were offered the best possible pain relief afterwards? What if you were offered the surgery but had to recover in a hospital where no one spoke your language, and you had no way of requesting more painkillers if the standard dose was not enough for you?

I’d also like to move the discussion away from pain, which both sides of the debate are (in my opinion) overly focused on. Pain is sometimes necessary in research. What isn’t always necessary is keeping animals in cramped quarters lacking environmental enrichment. I have seen facilities where the mice and rats lack even an exercise wheel, and where there are multiple animals in a cage so small I wouldn’t feel comfortable keeping even a single pet rat in it. That’s not necessary; that’s a choice, due to the fact that more space and more enrichment is expensive.

Again, I don’t think the argument has to be so black and white. We don’t have to argue that research animals are in constant, excruciating pain (because that is untrue). But we can also admit that research animals do often (possibly 43 percent of the time) experience pain as part of the research process. We can feel bad about that, but still do it, because the alternative is so unthinkable. And we can accept that if we’re asking these animals to give up their lives, we don’t also need to ask them to live in such unenriched environments. They require mental stimulation just like we do. If they were so different from us, we wouldn’t be using them to model us.

The indifference of researchers

Jessen argues that “researchers are deeply concerned about the condition of the animals they study.” I agree. Researchers aren’t unfeeling monsters, and I wish that the people arguing on the other side of this divide would stop trying to make them out to be.

However, I think researchers often (not always, but often) subscribe to the black and white version of this particular moral dilemma: it is necessary, so I don’t need to feel bad about it. I have every respect for and sympathy with someone who is living day in, day out with animals that they know will die at the end of the experiment. It would be easier if the cages were big enough, if the animals didn’t lack enrichment, if the painkillers were always sufficient and took away all the pain, if the animals had some place to go after non-terminal experiments. But despite my sympathy for the research community, I would like to see a little more effort on their part to address some welfare issues, and to recognize the moral difficulties inherent in animal research. I do think that it is possible to do animal research, and still sympathize with the viewpoint of people out there who find the idea of animal research disturbing. It should be disturbing. Even though it is necessary.

Moving forward

Am I saying that everyone who benefits from animal research should be guilt-stricken all the time? Of course not. That wouldn’t be very productive. I am saying we should recognize the shades of grey. And that, as a society, we should feel bad enough about animal research to make improving lab animal welfare more of a priority. More of the money that goes to research could go to making the lives of research animals more comfortable. (If a pet rat lives in a bigger cage, so should a research rat!) If they are giving their lives for us, and we recognize that that is wrong, we should also recognize that it is our responsibility to make their lives not just as pain free as possible, but as good as possible. We’re doing a decent job on the former. I don’t think we are working anywhere near hard enough on the latter.