- At a teaching facility, your vet student is your pet’s primary caretaker. She is the one who knows your pet the best. She has to present your pet’s clinical history to the residents and faculty every day, follow up on test results, and make sure nothing is overlooked or forgotten about. She is also the one who notices things like what kind of food your dog likes best, whether he likes to be taken a little farther from the hospital than usual so that he can pee on grass instead of stones, and takes time out of her day to cuddle with him if he looks sad. (To be fair, the techs also handle a lot of this sort of thing.)
- Your vet student is the one who lets you know how your dog is doing. She will call you at least once a day to tell you if your dog is stressed or not, and give you the updates that really matter, like “today he barked at me while I was writing up paperwork until I took him out of his cage to cuddle with him.” Sometimes hearing stories that remind you that your dog still has the same personality as he does at home is just as important emotionally as getting the complicated medical updates from the doctor.
- Your vet student is your liaison to the doctor. The doctor is a specialist who is very, very busy. He will give you lots of information, and you will try to digest it all, but you will have trouble really absorbing it. Your vet student is the one who will take the time to answer all your questions in terms you can understand. She will also be understanding if you are anxious about your pet and will tell you that you are going to do fine taking care of him once he comes home. Maybe she will even help you pad the blankets in your car just right before you settle him in to transport him.
- Your vet student is required to be a generalist. The faculty and residents on your pet’s case are all specialists. Sometimes having a generalist around is important. If your dog is in for orthopedic surgery, the specialists may be so focused on your dog’s joint problems that they may not think to perform a rectal exam on him, even though he is a ten year old intact male at risk for all sorts of cancer. But your vet student will remember. (The dog had a mass.)
Saturday, August 20, 2011
Things your vet student is good for
Recently, an owner refused to let me perform a physical examination on his dog. That was for the vet to do. I think he didn’t believe that I had any role in his dog’s care, and thought I was just along to watch and learn from the vets. Not so! (The examples below are all things that have happened to me and owners of my patients.)
Sunday, August 7, 2011
The curse of the missing uteruses, part three
The first dog I ever tried to spay had no uterus. (She had already been spayed.) And the first cow I ever did a reproductive exam on had no uterus. (She was a freemartin.) That should be enough missing uteruses for one lifetime. But no.
On a recent shelter medicine externship, I was spaying a kitten. On this externship, you get to spay several animals every day, and I had gotten comfortable enough at it that I was hoping to get through the entire surgery without ever asking for help. To understand what I was doing, you have to understand a little about cat uteruses. Human uteruses are one big sac, probably because we tend to have just one or two babies at a time. Cat uteruses are divided into two horns, each with an ovary at the top, and the horn and ovary are attached to the body wall to hold the whole contraption in place. The horns of pregnant cats fill up with kittens, all in a row.The two horns come together at their base, where there is a little uterine body, which connects to the cervix and from there to the vagina and the outside world. To spay a cat, you cut each ovary and horn away from the body wall. Then you have loose horns, and a base which still attaches to the cervix and vagina and outside world. You cut across the base, and then you have a free uterus and a spayed cat.
So I opened this kitten up, careful to make my incision very short. Longer incisions make visualizing your work easier, but obviously are more painful for the animal, and I had just been criticized on my previous spay for making too long an incision. I used my spay hook to fish around in the abdomen, found the first uterine horn and ovary, pulled them out, and cut them away from the body wall. I traced the now-free uterine horn back to the uterine body.
Finding the first horn is hard: you dip in with the spay hook and blindly bring stuff up, mostly intestines, which you have to repeatedly shove back in until you finally get the organ you’re looking for. Finding the second horn is easy: you follow the first one back to the uterine body, and then pull the second horn out where they both split off from the base. Except in this case, I couldn’t find it. I pulled on the uterine body, which should have made the horn pop out, but no go. I pulled harder. The uterine body started to fray. Oops! I didn’t want it to break before I could find the second horn. I had a moment of indecision: I really, really wanted to get through this whole operation without asking a vet for help. And the problem was probably just that I had made the incision too small. But I had seen too many episodes of ER in which overconfident students got into trouble in exactly this way, and if the uterus split apart before I had a chance to put a suture around it to stop any bleeding, that could potentially be dangerous for the kitten. So I called over Dr. Vine.
Dr. Vine assured me that my incision was an excellent size, and pulled on the uterine body some more. It promptly broke off in her hand. (I congratulated myself on setting her up for dealing with that situation instead of getting myself into it.) It was not a big deal, in the end: she hunted down the stump and we put some suture around it. And she said: This cat only has one uterine horn. It only has half a uterus.
Freakish! And cool. And do you know what? Cats that only have one uterine horn always, 100% of the time, have two ovaries. So if you don’t go hunt down that second ovary, they will still have heat cycles. (They won’t get pregnant, of course, but cats in heat are no fun to have around.) Dr. Vine asked me where I thought the ovary might be. I suggested, in my usual precise fashion, “Somewhere sort of near the... kidney?”
It turns out that that was exactly the answer she was looking for, because, even weirder: about 50% of cats who have only one uterine horn also have only one kidney. And this cat was one of them.
In the end, we found the ovary, just sitting there not really near anything, and we removed it. One more missing uterus for my collection, or half of one. These things come in threes, right? Does this experience count as my third missing uterus, or just two and a half?
On a recent shelter medicine externship, I was spaying a kitten. On this externship, you get to spay several animals every day, and I had gotten comfortable enough at it that I was hoping to get through the entire surgery without ever asking for help. To understand what I was doing, you have to understand a little about cat uteruses. Human uteruses are one big sac, probably because we tend to have just one or two babies at a time. Cat uteruses are divided into two horns, each with an ovary at the top, and the horn and ovary are attached to the body wall to hold the whole contraption in place. The horns of pregnant cats fill up with kittens, all in a row.The two horns come together at their base, where there is a little uterine body, which connects to the cervix and from there to the vagina and the outside world. To spay a cat, you cut each ovary and horn away from the body wall. Then you have loose horns, and a base which still attaches to the cervix and vagina and outside world. You cut across the base, and then you have a free uterus and a spayed cat.
So I opened this kitten up, careful to make my incision very short. Longer incisions make visualizing your work easier, but obviously are more painful for the animal, and I had just been criticized on my previous spay for making too long an incision. I used my spay hook to fish around in the abdomen, found the first uterine horn and ovary, pulled them out, and cut them away from the body wall. I traced the now-free uterine horn back to the uterine body.
Finding the first horn is hard: you dip in with the spay hook and blindly bring stuff up, mostly intestines, which you have to repeatedly shove back in until you finally get the organ you’re looking for. Finding the second horn is easy: you follow the first one back to the uterine body, and then pull the second horn out where they both split off from the base. Except in this case, I couldn’t find it. I pulled on the uterine body, which should have made the horn pop out, but no go. I pulled harder. The uterine body started to fray. Oops! I didn’t want it to break before I could find the second horn. I had a moment of indecision: I really, really wanted to get through this whole operation without asking a vet for help. And the problem was probably just that I had made the incision too small. But I had seen too many episodes of ER in which overconfident students got into trouble in exactly this way, and if the uterus split apart before I had a chance to put a suture around it to stop any bleeding, that could potentially be dangerous for the kitten. So I called over Dr. Vine.
Dr. Vine assured me that my incision was an excellent size, and pulled on the uterine body some more. It promptly broke off in her hand. (I congratulated myself on setting her up for dealing with that situation instead of getting myself into it.) It was not a big deal, in the end: she hunted down the stump and we put some suture around it. And she said: This cat only has one uterine horn. It only has half a uterus.
Freakish! And cool. And do you know what? Cats that only have one uterine horn always, 100% of the time, have two ovaries. So if you don’t go hunt down that second ovary, they will still have heat cycles. (They won’t get pregnant, of course, but cats in heat are no fun to have around.) Dr. Vine asked me where I thought the ovary might be. I suggested, in my usual precise fashion, “Somewhere sort of near the... kidney?”
It turns out that that was exactly the answer she was looking for, because, even weirder: about 50% of cats who have only one uterine horn also have only one kidney. And this cat was one of them.
In the end, we found the ovary, just sitting there not really near anything, and we removed it. One more missing uterus for my collection, or half of one. These things come in threes, right? Does this experience count as my third missing uterus, or just two and a half?
Friday, August 5, 2011
Land of eyeballs: ophthalmology rotation
I was really surprised at how interesting I found my ophthalmology rotation. Two weeks of eyeballs should have been mostly boring and creepy, right? But it turned out to be rife with my favorite kind of veterinary ethical issue: how we breed dogs.
Take the several bulldogs we saw who had so many facial wrinkles that their skin was folded over their eyes and rubbed against their eyeballs. (They also had yeast infections in the depths of their wrinkles, but that was a problem for a different department.) These dogs required surgical intervention to cut off the worst of the wrinkles. If they did not receive the surgery, they would be extremely uncomfortable (they all came in with red, squinty eyes), and would eventually get corneal ulcers which would proceed to infections and possible removal of the eye in question.
We also saw a raft of brachycephalic (flat-faced) dogs whose faces were so flattened that their eyes bulged out. Some of them could not completely close their eyelids. Their eyes were at risk for damage just due to being so out there in the world and unprotected. In the opinion of the ophthalmologists, pug owners all need to be given special eye care instructions when they acquire their new dog.
I asked the owner of one of the dogs that required surgery about where he had gotten the dog. He replied that the dog came from a breeder. I suggested that he get in touch with the breeder to let her know about the necessary surgery, so that she could use that information to help her choose wisely which dogs to breed in the future, and try to avoid producing more puppies with the problem. He replied in surprise, “I thought this was just a breed-related problem.”
Yes, these are breed-related problems. But breed-related isn’t synonymous with inevitable. It doesn’t mean we can’t try to avoid them as we create more dogs of that breed. Veterinarians can and should be more clear with their clients about this. They don’t have to be confrontational to do it! They don’t have to imply that the client made a mistake by purchasing the dog. They can instead look to the future: here’s what we can do to make the breed better.
Take the several bulldogs we saw who had so many facial wrinkles that their skin was folded over their eyes and rubbed against their eyeballs. (They also had yeast infections in the depths of their wrinkles, but that was a problem for a different department.) These dogs required surgical intervention to cut off the worst of the wrinkles. If they did not receive the surgery, they would be extremely uncomfortable (they all came in with red, squinty eyes), and would eventually get corneal ulcers which would proceed to infections and possible removal of the eye in question.
We also saw a raft of brachycephalic (flat-faced) dogs whose faces were so flattened that their eyes bulged out. Some of them could not completely close their eyelids. Their eyes were at risk for damage just due to being so out there in the world and unprotected. In the opinion of the ophthalmologists, pug owners all need to be given special eye care instructions when they acquire their new dog.
I asked the owner of one of the dogs that required surgery about where he had gotten the dog. He replied that the dog came from a breeder. I suggested that he get in touch with the breeder to let her know about the necessary surgery, so that she could use that information to help her choose wisely which dogs to breed in the future, and try to avoid producing more puppies with the problem. He replied in surprise, “I thought this was just a breed-related problem.”
Yes, these are breed-related problems. But breed-related isn’t synonymous with inevitable. It doesn’t mean we can’t try to avoid them as we create more dogs of that breed. Veterinarians can and should be more clear with their clients about this. They don’t have to be confrontational to do it! They don’t have to imply that the client made a mistake by purchasing the dog. They can instead look to the future: here’s what we can do to make the breed better.
Sunday, July 31, 2011
Repost: Learning from Domesticated Foxes
[This was originally a guest post on The Thoughtful Animal.]
Everyone loves reading about the Siberian fox experiment because domesticated silver foxes are so damn cute. There’s something deeply appealing about the idea of a cuddly fox. And the experiment raised some interesting questions about domestication. Could domestication really happen in just eight generations? (Apparently.) Domestication must just affect the brain and not the rest of the body, right? (Apparently not – domesticated foxes can have characteristic coat color changes, floppy ears, and curly tails, similar to morphologic differences between dogs and wolves.) But a research population of domesticated foxes hasn’t been maintained since the sixties just because they are cute. We’re still learning things from them. Like what? Get ready for some well-aged papers; a lot of this work was done back in the eighties.
Hormone and neurotransmitter soup
We use the hormone cortisol as a marker of stress: if you have more cortisol in your blood, you’re probably more stressed. It turns out, perhaps not surprisingly, that domesticated foxes have lower basal levels of cortisol than their unselected counterparts (Oskina, 1992). Their cortisol levels also don’t go up as high during a stressful experience as do the cortisol levels of unselected foxes (Harri, 2003). Personally, I think cortisol is going to play a key role in the mechanism of why domesticated animals are less flighty than wild ones. Cortisol levels influence the production of adrenaline: if you have more cortisol in your system, you are liable to make more adrenaline (Kvetnansky, 2009). If you have more adrenaline in your system, you are going to react more strongly to scary stimuli – in other words, your flight distance is going to increase. (Quick review – domesticated foxes were bred by selection for decreased flight distance from humans.) My friends and I noticed during our highly stressful first year of veterinary school, when our cortisol levels were certainly high, that were were inexplicably jumpy. One friend reported that she was so startled by the noise of a dropped glass that she actually screamed.
As for the ever-popular serotonin, the “happy hormone,” domesticated foxes have more of it in their midbrains and hypothalamuses (Popova, 1991). Yes, the same hypothalamus that is the beginning of the hypothalamic-pituitary-adrenal axis, which ends in the release of cortisol. Oh, and which is inhibited by having more cortisol already in the system, in a negative feedback loop.
There is nothing cuter than a baby domesticated fox
Wolf cubs have a much shorter socialization window than dog puppies, and this might be part of why it is so difficult to socialize a wolf cub to humans. It turns out that unselected fox kits have a shorter socialization window than domesticated fox kits, too. Prime socialization time in both lines seems to start around 30-35 days, when the kits can see and hear and are mobile enough to explore their surroundings. Like most very young animals, fox kits of this age aren’t as fearful as their adult counterparts; they have a chance to learn what is dangerous and what is not in their particular environment. A longer socialization window gives you more chances to learn that a variety of beings are not dangerous to you, but in the wild it also gives you a greater chance of getting eaten by something that is dangerous to you when you wander up to say hello to it.
Domesticated fox kits start showing fear of new objects after age 60-65 days. Unselected kits, on the other hand, start fearing novel things at day 40-45 (Belyaev, 1985). We don’t know what exactly causes this difference in a preprogrammed socialization window, but it’s very helpful to have these populations as we look for the cause.
An even lower level of programming
In recent years, researchers have had new tools to use in exploring the mechanisms of domestication in foxes, especially since the canine genome was sequenced. Comparing gene expression in the wolf and the dog is problematic, because they necessarily live in such different environments. Comparing gene expression in two populations of foxes raised in identical conditions is potentially much more fruitful. This research is in the early days. But as we learn more about the canine genome I think we’ll start finding some really interesting differences between the lines of domesticated and unselected foxes. My personal belief is that we’ll find subtle differences – maybe, rather than differences in actual genes, we’ll see changes in promoter sequences, which cause significant genes to be up or down regulated.
We’ve learned a lot from the Russian domesticated foxes so far, but we have a long way yet to go. We still have no real idea exactly what is at the root of the difference between a domesticated and undomesticated animal. Does the change in development affect cortisol and serotonin levels, or vice versa? Does just a single genetic modification cause all the physiologic changes we see? Or are we looking for a set of modifications? Hopefully the new genomic tools we’re developing will allow us to get to the bottom of the mystery.
References
OSKINA, I., & TINNIKOV, A. (1992). Interaction between cortisol and cortisol-binding protein in silver foxes (Vulpes fulvus) Comparative Biochemistry and Physiology Part A: Physiology, 101 (4), 665-668 DOI: 10.1016/0300-9629(92)90341-M
Harri M., Mononen J., Ahola L., Plyusnina I., Rekila T. Behavioural and physiological differences between silver foxes selected and not selected for domestic behaviour. Animal Welfare. 2003:305-314.
Kvetnansky, R., Sabban, E., & Palkovits, M. (2009). Catecholaminergic Systems in Stress: Structural and Molecular Genetic Approaches Physiological Reviews, 89 (2), 535-606 DOI: 10.1152/physrev.00042.2006
POPOVA, N., VOITENKO, N., KULIKOV, A., & AVGUSTINOVICH, D. (1991). Evidence for the involvement of central serotonin in mechanism of domestication of silver foxes Pharmacology Biochemistry and Behavior, 40 (4), 751-756 DOI: 10.1016/0091-3057(91)90080-L
BELYAEV, D., PLYUSNINA, I., & TRUT, L. (1985). Domestication in the silver fox (Vulpes fulvus Desm): Changes in physiological boundaries of the sensitive period of primary socialization Applied Animal Behaviour Science, 13 (4), 359-370 DOI: 10.1016/0168-1591(85)90015-2
Everyone loves reading about the Siberian fox experiment because domesticated silver foxes are so damn cute. There’s something deeply appealing about the idea of a cuddly fox. And the experiment raised some interesting questions about domestication. Could domestication really happen in just eight generations? (Apparently.) Domestication must just affect the brain and not the rest of the body, right? (Apparently not – domesticated foxes can have characteristic coat color changes, floppy ears, and curly tails, similar to morphologic differences between dogs and wolves.) But a research population of domesticated foxes hasn’t been maintained since the sixties just because they are cute. We’re still learning things from them. Like what? Get ready for some well-aged papers; a lot of this work was done back in the eighties.Hormone and neurotransmitter soup
We use the hormone cortisol as a marker of stress: if you have more cortisol in your blood, you’re probably more stressed. It turns out, perhaps not surprisingly, that domesticated foxes have lower basal levels of cortisol than their unselected counterparts (Oskina, 1992). Their cortisol levels also don’t go up as high during a stressful experience as do the cortisol levels of unselected foxes (Harri, 2003). Personally, I think cortisol is going to play a key role in the mechanism of why domesticated animals are less flighty than wild ones. Cortisol levels influence the production of adrenaline: if you have more cortisol in your system, you are liable to make more adrenaline (Kvetnansky, 2009). If you have more adrenaline in your system, you are going to react more strongly to scary stimuli – in other words, your flight distance is going to increase. (Quick review – domesticated foxes were bred by selection for decreased flight distance from humans.) My friends and I noticed during our highly stressful first year of veterinary school, when our cortisol levels were certainly high, that were were inexplicably jumpy. One friend reported that she was so startled by the noise of a dropped glass that she actually screamed.
As for the ever-popular serotonin, the “happy hormone,” domesticated foxes have more of it in their midbrains and hypothalamuses (Popova, 1991). Yes, the same hypothalamus that is the beginning of the hypothalamic-pituitary-adrenal axis, which ends in the release of cortisol. Oh, and which is inhibited by having more cortisol already in the system, in a negative feedback loop.
There is nothing cuter than a baby domesticated fox
Wolf cubs have a much shorter socialization window than dog puppies, and this might be part of why it is so difficult to socialize a wolf cub to humans. It turns out that unselected fox kits have a shorter socialization window than domesticated fox kits, too. Prime socialization time in both lines seems to start around 30-35 days, when the kits can see and hear and are mobile enough to explore their surroundings. Like most very young animals, fox kits of this age aren’t as fearful as their adult counterparts; they have a chance to learn what is dangerous and what is not in their particular environment. A longer socialization window gives you more chances to learn that a variety of beings are not dangerous to you, but in the wild it also gives you a greater chance of getting eaten by something that is dangerous to you when you wander up to say hello to it.
Domesticated fox kits start showing fear of new objects after age 60-65 days. Unselected kits, on the other hand, start fearing novel things at day 40-45 (Belyaev, 1985). We don’t know what exactly causes this difference in a preprogrammed socialization window, but it’s very helpful to have these populations as we look for the cause.
An even lower level of programming
In recent years, researchers have had new tools to use in exploring the mechanisms of domestication in foxes, especially since the canine genome was sequenced. Comparing gene expression in the wolf and the dog is problematic, because they necessarily live in such different environments. Comparing gene expression in two populations of foxes raised in identical conditions is potentially much more fruitful. This research is in the early days. But as we learn more about the canine genome I think we’ll start finding some really interesting differences between the lines of domesticated and unselected foxes. My personal belief is that we’ll find subtle differences – maybe, rather than differences in actual genes, we’ll see changes in promoter sequences, which cause significant genes to be up or down regulated.
We’ve learned a lot from the Russian domesticated foxes so far, but we have a long way yet to go. We still have no real idea exactly what is at the root of the difference between a domesticated and undomesticated animal. Does the change in development affect cortisol and serotonin levels, or vice versa? Does just a single genetic modification cause all the physiologic changes we see? Or are we looking for a set of modifications? Hopefully the new genomic tools we’re developing will allow us to get to the bottom of the mystery.
References
OSKINA, I., & TINNIKOV, A. (1992). Interaction between cortisol and cortisol-binding protein in silver foxes (Vulpes fulvus) Comparative Biochemistry and Physiology Part A: Physiology, 101 (4), 665-668 DOI: 10.1016/0300-9629(92)90341-M
Harri M., Mononen J., Ahola L., Plyusnina I., Rekila T. Behavioural and physiological differences between silver foxes selected and not selected for domestic behaviour. Animal Welfare. 2003:305-314.
Kvetnansky, R., Sabban, E., & Palkovits, M. (2009). Catecholaminergic Systems in Stress: Structural and Molecular Genetic Approaches Physiological Reviews, 89 (2), 535-606 DOI: 10.1152/physrev.00042.2006
POPOVA, N., VOITENKO, N., KULIKOV, A., & AVGUSTINOVICH, D. (1991). Evidence for the involvement of central serotonin in mechanism of domestication of silver foxes Pharmacology Biochemistry and Behavior, 40 (4), 751-756 DOI: 10.1016/0091-3057(91)90080-L
BELYAEV, D., PLYUSNINA, I., & TRUT, L. (1985). Domestication in the silver fox (Vulpes fulvus Desm): Changes in physiological boundaries of the sensitive period of primary socialization Applied Animal Behaviour Science, 13 (4), 359-370 DOI: 10.1016/0168-1591(85)90015-2
Saturday, July 23, 2011
The ethics of dog breeding: to breed or not to breed?
It’s challenging to breed purebred dogs well. You have to balance appearance, health, and temperament, and of course by “health” I actually mean “2598237 different possible inherited diseases.” You breed or buy the best animal you can (no small task in itself), you compete with it to prove its ability and conformance to the breed standard, and then when it is an adult the time comes to breed it. Before you breed, you have to make sure the animal is physically healthy. You perform perhaps thousands of dollars worth of tests towards this goal. If your star fails any one of them, you should consider not breeding it, even if it is otherwise a great breeding prospect. If it fails a really important test — like the assessment of the likelihood of developing hip dysplasia in a breed that is notorious for its hip problems, like the golden retriever — then you really shouldn’t breed the animal.
Time was, dog breeders had big kennels, with dozens of dogs. If one of them turned out to have an inheritable health problem, it was fairly easy to just remove that animal from the breeding program. After all, if you have 50 dogs and can only breed 49 of them, what’s the big deal? These days, people have less land, and dog breeders tend to have smaller numbers of dogs. So what happens if you are the owner of a single, beloved pet and you really want to try to improve the breed by having a litter from this pet? You show, you compete, you have health tests, and the animal fails the test for healthy hips. Now it’s not just a question of not breeding a single animal. Instead, it’s a question of not being able to breed at all, unless you get another dog and start over. What if that one has a health problem too, and you really don’t want to have three dogs in your house?
It’s a tangled issue. Personally, I think dogs do better in homes than in kennels, generally speaking (although I recognize that there are some private kennels out there containing some very happy dogs). But I also think that if we are going to be selecting dogs for beauty, as we do with show dogs, we have a responsibility to not let health fall by the wayside. Making the breeding of healthy dogs easier is a good thing. It’s sad to think that the fact that more dogs are living inside as pets makes breeding responsibly more difficult.
Time was, dog breeders had big kennels, with dozens of dogs. If one of them turned out to have an inheritable health problem, it was fairly easy to just remove that animal from the breeding program. After all, if you have 50 dogs and can only breed 49 of them, what’s the big deal? These days, people have less land, and dog breeders tend to have smaller numbers of dogs. So what happens if you are the owner of a single, beloved pet and you really want to try to improve the breed by having a litter from this pet? You show, you compete, you have health tests, and the animal fails the test for healthy hips. Now it’s not just a question of not breeding a single animal. Instead, it’s a question of not being able to breed at all, unless you get another dog and start over. What if that one has a health problem too, and you really don’t want to have three dogs in your house?
It’s a tangled issue. Personally, I think dogs do better in homes than in kennels, generally speaking (although I recognize that there are some private kennels out there containing some very happy dogs). But I also think that if we are going to be selecting dogs for beauty, as we do with show dogs, we have a responsibility to not let health fall by the wayside. Making the breeding of healthy dogs easier is a good thing. It’s sad to think that the fact that more dogs are living inside as pets makes breeding responsibly more difficult.
Tuesday, July 19, 2011
The art of dog breeding: Puppy has two daddies
Not just every puppy has two daddies. How would it happen?
It’s a long story, so stick with me. Let’s say you’re deeply involved in the dog world, and love a particular breed of dog. You breed to improve that breed. You have a young bitch that you are considering breeding. You start out by taking this bitch to dog shows, doing that circuit until the bitch has earned her championship after a number of wins at different shows. This shows that the bitch is conformationally excellent enough to be worth breeding. You may also work with the bitch in some other area, like competition obedience, tracking, or agility.
When the time comes to breed, there is more work to do. You have to make sure the bitch is genetically good material. You know what problems are common in the breed, so you test for those. There are some problems (like hip dysplasia) which are so common that breeders test for them in almost every breed; there are some that are more rare. Some tests are genetic tests done on DNA samples. Some are just the sorts of tests any vet might do to see if the levels of different chemicals in the blood are within normal ranges, or if they are suggestive of certain conditions. All these tests have to be done on both sire and dam.
Who’s the sire? You should pick out a sire that complements this bitch well. No animal is perfect. If the bitch’s biggest failing is her less than perfect hip conformation, then the sire should have really exceptional hip conformation, to balance that problem out. They should not be too closely related, either.
The right sire may live across the country or across the world from the bitch. If he’s far away, artificial insemination will be necessary (although some animals get transported quite a distance for sexual liaisons, and some bitches are artificially inseminated even though the dog is in the next room). When exactly should this occur? If the dog is prime breeding material, his semen will be very expensive, not to mention the fees for implanting it (more on that later). So you want to do it as few times as possible.
It’s also important to know as precisely as possible when the bitch ovulated, because this helps predict when she will give birth. So ovulation prediction is an important part of this process. It involves blood tests over multiple days, done by a veterinarian.
Once you know what the bitch’s three fertile days will be, how will you get the semen in? You can choose natural service (the old fashioned method), artificial insemination into the vagina, or intra-uterine insemination (surgical insemination directly into the uterus). This last approach is the most reliable, although of course it is also the most invasive and expensive.
If you don’t choose natural service, you may be getting either fresh semen (from the dog in the next room), fresh chilled and shipped overnight (from somewhere on your continent, collected the previous day), or frozen (from anywhere in the world, and possibly as venerable as twenty years old). Why would you artificially inseminate fresh semen, if the dog is right there? Some bitches can be cranky if they don’t approve of the dog on offer, and there can be violence. The owner of an expensive (or well loved!) stud dog might not wish to risk his injury.
Now it comes down to it. Many breeders will have spent thousands of dollars to get to this point. Some will have spent tens of thousands. They really, really want to have a successful impregnation. The fresher the semen, the more reliable it is. If the best possible sire is only providing frozen semen for whatever reason, the chances are significant that the bitch will not get knocked up. So what do you do?
On the bitch’s first fertile day, you use the frozen semen from the preferred sire. You hope that all her eggs get fertilized by this semen, but if some are left over, you call in the backup sire, someone local who can provide fresh semen. Hopefully any eggs that failed to get fertilized by the first sire will get handled by the second. You may well end up with puppies from each sire in the litter, but that’s fine; you can DNA test them to know who’s sired by whom. And that is how a puppy can have two daddies, or, at least, a litter can.
(Note: I skipped over the numerous ethical issues brought up in this story. For today, I just wanted to share with you some of the surprising tools available to dog breeders today.)
It’s a long story, so stick with me. Let’s say you’re deeply involved in the dog world, and love a particular breed of dog. You breed to improve that breed. You have a young bitch that you are considering breeding. You start out by taking this bitch to dog shows, doing that circuit until the bitch has earned her championship after a number of wins at different shows. This shows that the bitch is conformationally excellent enough to be worth breeding. You may also work with the bitch in some other area, like competition obedience, tracking, or agility.
When the time comes to breed, there is more work to do. You have to make sure the bitch is genetically good material. You know what problems are common in the breed, so you test for those. There are some problems (like hip dysplasia) which are so common that breeders test for them in almost every breed; there are some that are more rare. Some tests are genetic tests done on DNA samples. Some are just the sorts of tests any vet might do to see if the levels of different chemicals in the blood are within normal ranges, or if they are suggestive of certain conditions. All these tests have to be done on both sire and dam.
Who’s the sire? You should pick out a sire that complements this bitch well. No animal is perfect. If the bitch’s biggest failing is her less than perfect hip conformation, then the sire should have really exceptional hip conformation, to balance that problem out. They should not be too closely related, either.
The right sire may live across the country or across the world from the bitch. If he’s far away, artificial insemination will be necessary (although some animals get transported quite a distance for sexual liaisons, and some bitches are artificially inseminated even though the dog is in the next room). When exactly should this occur? If the dog is prime breeding material, his semen will be very expensive, not to mention the fees for implanting it (more on that later). So you want to do it as few times as possible.
It’s also important to know as precisely as possible when the bitch ovulated, because this helps predict when she will give birth. So ovulation prediction is an important part of this process. It involves blood tests over multiple days, done by a veterinarian.
Once you know what the bitch’s three fertile days will be, how will you get the semen in? You can choose natural service (the old fashioned method), artificial insemination into the vagina, or intra-uterine insemination (surgical insemination directly into the uterus). This last approach is the most reliable, although of course it is also the most invasive and expensive.
If you don’t choose natural service, you may be getting either fresh semen (from the dog in the next room), fresh chilled and shipped overnight (from somewhere on your continent, collected the previous day), or frozen (from anywhere in the world, and possibly as venerable as twenty years old). Why would you artificially inseminate fresh semen, if the dog is right there? Some bitches can be cranky if they don’t approve of the dog on offer, and there can be violence. The owner of an expensive (or well loved!) stud dog might not wish to risk his injury.
Now it comes down to it. Many breeders will have spent thousands of dollars to get to this point. Some will have spent tens of thousands. They really, really want to have a successful impregnation. The fresher the semen, the more reliable it is. If the best possible sire is only providing frozen semen for whatever reason, the chances are significant that the bitch will not get knocked up. So what do you do?
On the bitch’s first fertile day, you use the frozen semen from the preferred sire. You hope that all her eggs get fertilized by this semen, but if some are left over, you call in the backup sire, someone local who can provide fresh semen. Hopefully any eggs that failed to get fertilized by the first sire will get handled by the second. You may well end up with puppies from each sire in the litter, but that’s fine; you can DNA test them to know who’s sired by whom. And that is how a puppy can have two daddies, or, at least, a litter can.
(Note: I skipped over the numerous ethical issues brought up in this story. For today, I just wanted to share with you some of the surprising tools available to dog breeders today.)
Monday, July 11, 2011
Neurology rotation
I just completed my two-week neurology rotation. You might think that, because I love dog brains, this would have been right up my alley. Actually, I love the parts of brains that help us learn, fear, trust, and love. Veterinary neurology, on the other hand, is a big game of Hunt the Lesion. A dog comes in uncoordinated and with a head tilt. Where in its brain, cranial nerves, or spinal cord is the problem?
A good neurologic exam can localize the problem to the cerebrum, the cerebellum, one or more of the cranial nerves, the spinal cord in front of the front legs, the spinal cord over the front legs, the spinal cord between the front and back legs, the spinal cord over the back legs, the spinal cord behind the back legs, or something more general (a diffuse muscle, nerve, or muscle/nerve junction problem). Once we had an idea where the problem was, we usually sent the animal in to the MRI scanner (a luxury at a large referral hospital; we received a lot of animals coming in just for the MRI, referred from places that don’t have them). This allowed us to see exactly where the lesion was, and to get some information about what kind of lesion it was (intervertebral disc extruded into the spinal canal? A stroke? Cancer?).
I did enjoy neurology, even though Hunt the Lesion isn’t my favorite game. There was a surprising amount of basic medicine to learn; I got a lot more comfortable with how to manage post-surgical animals (we did lots of vertebral surgeries), as well as how to approach a diagnosis (young animals are more likely to have congenital or infectious problems or to have eaten toxins; older animals are more at risk for stroke or cancer). Practicing basic medicine is always good! So it was an enjoyable rotation, but now I am really looking forward to my upcoming four whole weeks of elective time.
A good neurologic exam can localize the problem to the cerebrum, the cerebellum, one or more of the cranial nerves, the spinal cord in front of the front legs, the spinal cord over the front legs, the spinal cord between the front and back legs, the spinal cord over the back legs, the spinal cord behind the back legs, or something more general (a diffuse muscle, nerve, or muscle/nerve junction problem). Once we had an idea where the problem was, we usually sent the animal in to the MRI scanner (a luxury at a large referral hospital; we received a lot of animals coming in just for the MRI, referred from places that don’t have them). This allowed us to see exactly where the lesion was, and to get some information about what kind of lesion it was (intervertebral disc extruded into the spinal canal? A stroke? Cancer?).
I did enjoy neurology, even though Hunt the Lesion isn’t my favorite game. There was a surprising amount of basic medicine to learn; I got a lot more comfortable with how to manage post-surgical animals (we did lots of vertebral surgeries), as well as how to approach a diagnosis (young animals are more likely to have congenital or infectious problems or to have eaten toxins; older animals are more at risk for stroke or cancer). Practicing basic medicine is always good! So it was an enjoyable rotation, but now I am really looking forward to my upcoming four whole weeks of elective time.
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