Animal Blood Types

A couple of weeks ago Paul asked this and I'm finally getting around to it. 

I wonder if you could discuss the issue of blood groups and blood transfusions in dogs.

I understand that large breed dogs often are blood donors and that unlike us humans, at least my understanding is, that a dog can receive a blood transfusion from another dog without the blood being of the same blood group as the donor's. Am I correct? How does this work? without killing the dog. Is it only once in a dog's lifetime that a transfusion of another blood group can be done? Are the blood groupings for dogs the same as humans?

 

Excellent question, Paul!  I'll try to answer this question in a way that most laypeople can understand.  All of my veterinary readers please be patient if I don't get into quite the detail that I know is out there.  I'm also going to deal just with dog and cat blood types, as these are the most common pets owned and the ones I'm most familiar with.

 

For those who haven't quite caught on, yes, animals have blood types.  Humans have four:  A, B, AB, and O.  When doing blood transfusions we have to "type" a person's blood and find out which kind it is.  Type O is a "universal donor", meaning anyone can receive this type of blood, but those with Type O can only receive their on blood type.  AB is the opposite, being a "universal acceptor" and can take any blood type but can only donate to other ABs.  Humans naturally have antibodies against blood types other than their own, so if someone receives an incompatable blood type the body will not properly recognize it and will attack it as a "foreign" substance.  This reaction can be serious and even fatal, which is why blood typing is important.  This isn't really a concern with O blood because this type doesn't have the "triggers" on their surface that the other three have, so antibodies will not recognize or attack the cells.

 

Dogs have eight basic blood types, though as many as 12 may exist.  The types are numbered and are structured differently than in humans.  Dogs also are believed to not have naturally occurring antibodies against other blood types (again, different than in humans).  This means that a first-time transfusion between two untyped dogs is very unlikely to cause a suddent transfusion reaction, even if their blood types are different.  However, if the blood types are different, the recipient can then develop antibodies against the donor blood type.  The next time this blood type is given, there is a chance of a reaction to the "foreign" blood.

 

Cats have three basic blood types, named A, B, and AB.  AB is a rare blood type, though is found very commonly in the Abyssinian breed.  Cats do have natural antibodies against different blood types, like in humans, but the severity differs.  Type B cats have a high antibody level against Type A, and are likely to have a very serious reaction to even a single transfusion with A.  Type A cats have lower levels against Type B and so reactions to B tend to be minor (however, these donor blood cells won't last as long in the body compared to A blood).  AB blood can be safely given to cats of either other blood type.

 

So how is all of this relevant?  Dogs can generally receive any other dog's blood for a transfusion if it's the first time the recipient has ever had a transfusion.  After the first time it becomes important to type the blood to prevent a reaction.  This is very nice in emergency situations as the vast majority of dogs have never received donor blood so if you have to do a quick transfusion you can really pick any canine blood sample.  Cats aren't so lucky, as you need to type the blood of the donor and recipient every time or risk a potentially life-threatening reaction.

 

Many areas have pet blood donor programs, especially at veterinary colleges.  In US there is also a national pet blood bank that can overnight blood to any clinic.  Donors usually receive free health screening and testing to make sure they are good candidates for donating, since there is normally no compensation given for allowing your pet to be a donor.

 

Paul, this was a great question!  Thanks for asking it!

Moving Elderly, Sick Pets

Nathalia send me this email...

I have two elderly cats, one is approaching 18 and the other 16.5. My 16 year old is epileptic and receives medication 3 times a day. She has been seizure free for about 4 months, but they can start up at any time…or so has been the case since they began about six years ago. My 18 year old is healthy, although the vet tells me she is in stage 1 or 2 of chronic kidney disease.
I am moving to New Zealand in August. I have begun preparations for moving the girls, but my vet suggested that I leave them behind because she did not think they could withstand the flight from Indianapolis to Auckland (flying cargo for most of the flight), plus being quarantined for 30 days in New Zealand upon arrival. (she was worried about my 16 year old going long stretches of time without her medication)
I am really torn about what to do. I could break the trip up, at least from Indy to LAX to give the girls a few days of rest before the long cargo flight. And from what I gather, I could visit them in quarantine and they would take care of administering medications.
I do have family members who have agreed to adopt my girls, but I’m devastated by the thought and have been trying to figure out what kind of impact that would have on them, as opposed to the stressful move with me. Do you have any thoughts on this?
 
I would tend to agree with your vet that this might be too much for kitties.  Stress is one of the things that can induce a seizure, and you won't be able to give medications while your epileptic kitty is flying across the Pacific.  I'm also not sure how comfortable you would be putting the care of old, less-than-healthy cats in the hands of a stranger for a month.  This would be a very, very hard trip on them physically, and though they might make it through just fine, I believe that there is an equal chance of having problems.  Going to live with some of your family members would also be stressful, but I don't think that it would be quite as bad as such a long international trip.
 
I know that this is an extremely difficult decision, and it's hard to leave such life-long partners.  As tough as it is, this is a time to put aside your own feelings and look at what's best for your cats.  Unfortunately, there is no guarantee either way, as they could do fine traveling with you and have problems back with family.  But I do think that the odds are best for them by staying in the US.  If they were younger and healthy, I wouldn't have any qualms about them traveling so far, but that's not the case here. 
 
In the end it's a matter of better or worse odds and not a black-and-white issue.  If you feel that you can't be without them and that they are so bonded to you that they'd suffer away from you, then it might be worthwhile to take the risk of travel.
 
Good luck with your decision!

Make It Stop!

Part of being a vet is dealing with noisy dogs.  Most of the time we get used to it and learn to tune it out.  Frankly, you have to because it's just about a daily occurrence.  Dogs bark to communicate with each other, let other know they are there, and express their "displeasure" at being confined.  Any and all of these reasons can cause a dog to bark when in the clinic.  And once one starts barking it entices others to join in.  At times it can be quite a cacophony!  I've been having to put up with barking for about 27 years now, and you'd think I'd be used to it.  Most of the time I am, but sometimes it gets to me.

Today we had a little Yorkshire terrier in for a dental cleaning.  He came with a housemate, a shih-tzu, and it quickly became evident that they were closely bonded.  We kept them together initially, but had to separate them once we started the cleanings.  The shih-tzu went first, leaving the Yorkie alone.  Once by himself the Yorkie started barking non-stop with a particularly reverberating, high-pitched yapping.  This went on and on and on and on!  Once his friend was in recovery there was a delay until his own dental, during which he continued to bark.  We couldn't keep them together since one was still waking up and it wouldn't be safe.  Finally the Yorkie's dental happened and we had some blissful quiet for a while.  However, he was quickly done and work up surprisingly fast.  As soon as he was awake he began barking again! 

This was so bad that all of the clients could hear him in the rooms.  I was talking to an elderly lady about the coccidia her dog had.  The lady had a hearing aid, which really amplified the particular frequency of the dog's barking, making it very difficult for her to hear and understand me.  I had to have her to into the lobby in order for her to be able to hear my tech's at-home instructions.

Finally both dogs were awake enough that we could put them back together, and silence again reigned.  It was such a nice switch.  Normally barking doesn't get to me that much, but to paraphrase Jayne Cobb "he was starting to damage my calm." (Bonus points to everyone who correctly understands that reference)  I seriously wanted to throttle the little thing to get it to be quiet and was glad when he finally quieted down. 

Just one of the many aspects of being a veterinarian that most people don't think about!

Men Running From Women

Veterinary medicine has become interesting regarding gender shifts.  In 1960 the profession was 98% male.  Today it's 50.9% female.  From 1976 to 1995 the enrollment rate of men entering veterinary school decreased by more than half and the female applicants doubled.  Currently enrollment in US vet schools is 70-80% female, and 2009 was the first year that women menbers of the American Veterinary Medical Association outnumbered men.  It's no secret to anyone paying attention that this has become and will increasingly become a female-dominated profession.

The question is "why?"  Most people have explained the shift in gender demographics in relation to women's rights, changing gender perceptions, acceptance of women in medicine, lower wages discouraging men, and other similar factors.  But a recent report suggests another reason.  To quote the article from DVM Magazine...

Research suggests that men avoid college majors and graduate fields that are 24 to 54 percent female, Lincoln points out in her study. On college visits, men who see a classroom full of women may be intimidated to apply—a theory backed by statistics collected for the study.



"The explanation of reduced barriers to admission for women has merit, although it fails to explain why other professions that have also eliminated that bias have not feminized or not at the same rate," Lincoln argues. "The results of this study demonstrate only one consistent difference between male and female application patterns—men's strong negative response to women's increasing enrollment."


Feminization of the veterinary profession has been fueled more by lower rates of college graduation among men and their aversion to female students than women being attracted to the field, Lincoln says. Similar trends have been noted in fields now dominated by women, like pharmacy, she adds. The trend now may also be extending to human medicine, with female applicants to American medical schools surpassing those of men for the first time in 2003. Wage stagnation over the last two decades has been linked as a factor in that case, with men more often choosing the more lucrative fields of business or law over medicine. Men also tend to revise their career plans based on decline in occupational prestige, employment security and promotional prospects, Lincoln adds.


Very interesting conclusions!  According to the study, for every 1% increase in the female veterinary student body there will be a 1.7% decrease in male applications the following year.  So the decline in male veterinarians may be because they're scared to work in a profession dominated by women!  Personally I haven't seen that attitude among my male colleagues, but then we're the ones who actually did apply and therefore seem to be the exception to the data in this study.

Women, here's your proof that men really are the weaker and more easily intimidated sex!

When To Spay Or Neuter

A common debate among veterinarians, shelters, and clients is when to have a dog or cat spayed or neutered.  The consensus and opinions have changed over time, and there can be some big disagreements depending on someone's experience and education.  A recent article in the journal Veterinary Medicine discussed the current views on the pros and cons of this kind of surgery on very young pets, and I thought it would be good to bring it up here.

First of all, we need to define "pediatric" spaying and neutering.  This normally means performing the surgery between 8 and 16 weeks of age.  Older vets would balk at this because the recommendation used to be to wait until six months old or after one heat cycle.  Current thinking has pretty much disproven the need to wait this long, so now most vets are spaying and neutering between four and six months old.  Most of the very young surgeries are done through shelters and rescue agencies, wanting the pet sterilized prior to being adopted out. 

Since there are many concerns about doing pediatric surgeries, let's briefly mention some of the myths (all taken from the above article) of the risks of doing these procedures.
1.  Obesity.  A long-term study at Cornell University showed that dogs who had early spays and neuters actually had a decrease in obesity risk.
2.  Stunted growth.  Removing the hormones early actually allows the growth areas of bones to stay open longer, so pediatric spays and neuters can grow taller than their late-sterilized counterparts.
3.  Hip dysplasia.  The jury is still out on this, but studies seem to be showing no increase or only a slight increase in risk.
4.  Feline urinary obstruction.  No increase risk has been found.  In fact, the diameter if the urethra is no different in cats neutered at 7 weeks or 7 months old.
5.  Urinary incontinence.  Again, the results are mixed.  One study showed an increased risk in females spayed before 12 weeks old, one showed no increased risk, and one showed an increased risk if spayed after the first heat cycle.

So overall, there appear to be no documentable long-term risks to surgical sterilizing at 2-4 months old.  What about surgical risk?  With current anesthetics and monitoring, the risks are not significantly different than waiting until later.  This was even true when I was in vet school in the late 90s, which is where I first saw some of this data.  As long as the vet is careful and monitors adequately, the surgery can be just as safe as in a six month old pet.

So with this information, why don't more people spay and neuter early?  In part I believe it's an ingrained tradition and habit in the veterinary profession.  We're just used to doing it at a certain age, and doing it younger makes us nervous because we don't really have personal experience with it.  I also think that it has to do with the timing of vaccines.  We finish the vaccines at around four months old, and it's easier to keep them on a regular schedule if we don't throw a surgery in prior to that.  It's simply convenient timing that once we finish the puppy/kitten boosters we next schedule their surgery.  But based on available data, there aren't many good reasons to have to wait that long.

Now does this mean that we as a profession should move to spays/neuters at three months old?  No, I don't think so.  There's really nothing wrong with doing it at the 4-6 month mark as most vets seem to do.  But it does mean that we shouldn't be afraid to do it younger, and shouldn't criticize those who do.  I'll continue to recommend the surgery at around four months old, but I have done it as early as 10 weeks (for reasons other than needing them sterilized) and had no issues at all.

Food for thought!

Expanding Opportunities

More and more this blog seems to be affording me some unique opportunities.  I've been able to connect with people around the world and in every hemisphere, I've reconnected with a client, and I've been able to share my knowledge to a far wider audience than I ever imagined.  Though I'm far from a big-time blogger, this whole thing has grown bigger than I realistically thought would happen.

Recently I was interviewed for an online college website, talking about what it takes to become a vet.  You can find the article here.  The interviewer paraphrased a few of my statements, but the answers are mine.  These are also similar questions that I have answered in this blog on previous occasions, so long-time readers may find some similarities.  And since I've gone through these questions before, I probably won't answer them again and will instead direct inquiries to previous posts and this article.

It's interesting how our world has change and how information now spreads.  In modern times bloggers are often well known and sometimes have real influence and power (just look at elections in the last few years).  When I graduated vet school in 1997 the Internet was well established, but still hadn't reached its potential.  Things like Google, Wikipedia, and blogging wasn't yet known.  Look how far we've come over the last decade! 

There is another big opportunity that I've been given and has developed over the last 10 days.  I'm not ready to fully detail what's going to happen, but things should be settled within a few weeks and then I can share and we can Gab about it.

Taking A New Oath

When we graduate to become veterinarians, we must take an oath stating our sincerity in our chosen profession. For only the third time in history, the oath in the United States has been revised by the American Veterinary Medical Association.  The original oath was adopted in 1954, then revised in 1969, 1999, and now 2011.  Here is the oath that every US veterinarian takes:

"Being admitted to the profession of veterinary medicine, I solemnly swear to use my scientific knowledge and skills for the benefit of society through the protection of animal health and welfare, the prevention and relief of animal suffering, the conservation of animal resources, the promotion of public health, and the advancement of medical knowledge."

Some of this oath may be surprising to the lay-person.  Promotion of public health?  Yep, vets historically have been called on to inspect meat and animal food sources, as well as monitor diseases carried from animals to humans.  Scientific knowledge?  Thought it may not seem obvious at first, we are trained as medical scientists and as critical thinkers.

So what's new?  The part about preventing and relieving animal suffering.  Though the AVMA doesn't define what entails "animal suffering", it hopes to make a statement by this stance, especially with the "prevention" as a proactive view.  Truthfully, I'm not entirely sure how important the change is.  The oath isn't legally binding and doesn't necessarily constitute practice standards.  I can also see lots of arguments against food production, an always touchy subject with the AVMA, as many feel that production animals are suffering in their circumstances.  Taking a tough stand on animal suffering is good, as we need to recognize the importance of pain control and other things that can negatively impact an animal's life.  But by not defining what "suffering" means, the AVMA is being rather vague (and probably deliberately so).

I remember when I recited that oath at the hooding ceremony and how important I felt.  At that time the oath really meant something and I listened to every word.  Though I don't discount the value of such a standard oath, I have to admit that I haven't really thought about it much over the last 13 years.  Time and perhaps a touch of cynicism has made me realize that saying the words doesn't really affect my day-to-day life and practice.

So for better or for worse, newly graduating vets will be reciting the above oath.  Will this change the profession or make them better vets?  Unlikely.  But it shows how the profession changes along with society, and we have come a long way from the beginnings of primarily seeing livestock.