Newsworthy: Veterinarians Find Infections Faster by Monitoring Nt-pCNP

"Stinger", a dog with sepsis from a bite wound. Image from Valley Center Veterinary Clinic, Valley Center, CA.

N-terminal portion of pro C-type natriuretic peptide. Try to say that one three times fast. ScienceDaily has a cool article detailing a couple new studies showing that this peptide (Nt-pCNP) could be a solid indicator of sepsis as opposed to a generalized inflammatory response. It could potentially be added to current serum chemistry analysis, or packaged as an ELISA snap for quick, in-house diagnostics for pertinent cases.

Overuse of antibiotics has been a long term problem that is being well addressed in human medicine, however they are used much more broadly and liberally in animals due to their non-prescription access (especially in large animal work), and their use as a diagnostic tool for patients who can’t speak and often can’t afford thorough diagnostics. A veterinarian who’s client is unwilling to pay for a culture will often send broad spectrum antibiotics home anyway as a less expensive option in the hopes that they will take care of the problem.

I was unable to find a chemistry profile of Nt-pCNP, but the journal article itself talks a bit about C-type natriuretic peptide. CNP is produced by vascular endothelial cells and immune system macrophages. It “inhibits microbial growth and modifies pathogenicity of microorganisms” (DeClue, 2011). The problem with looking for just CNP as an indicator of sepsis is that it has a very short half life, and tends to degrade even faster in removed serum. Therefore, the researchers decided to use Nt-pCNP as their target molecule.  Nt-pCNP is created in a 1:1 ratio with CNP as a byproduct, and is much more durable and long-lived in both the bloodstream and collected serum.

The results of the study support the hypothesis  that CNP is a good indicator of sepsis, however like anything else, it’s not ideal. CNP was shown to be a poor indicator of sepsis when the infection was peritoneal. This includes gastrointestinal perforations or other possible infections found within the peritoneum (the authors mention that using peritoneal fluid as opposed to serum from a distal point may yield better sensitivity). Taking these false negatives into account, the test had a 65.5% sensitivity, for all other origins of sepsis in the study, sensitivity was 92%. Unfortunately, there appears to be a large potential for ambiguous negatives when peritoneal infection is suspected, but it’s always important to remember to educate clients that medicine is rarely black and white. It’s nice that House is able to identify exactly what’s wrong with each of his patients every week, but most of the time, we’re just going to give them supportive care based on the most likely result. Some of the limitations of the study that the authors mentioned were the small sample size and uncontrolled natures of the ailments that may have influenced the blood chemistry (samples taken from bacterial vs. viral infections, condition as of admission, underlying secondary infection or ailment, etc.).

In the case of this test and many other lab tests, positives are very definitive and help us out, while negatives are ambiguous. This is true whether it’s a heartworm test, fine needle aspirate, fecal flotation, radiology, or any number of other diagnostic tests. Every one is a tool, and hopefully looking at Nt-pCNP levels will give us another way to confirm sepsis while our cultures are growing at the lab, or perhaps offering another faster or less expensive option that the situation necessitates.
This post was chosen as an Editor's Selection for ResearchBlogging.org
DeClue AE, Osterbur K, Bigio A, & Sharp CR (2011). Evaluation of serum NT-pCNP as a diagnostic and prognostic biomarker for sepsis in dogs. Journal of veterinary internal medicine / American College of Veterinary Internal Medicine, 25 (3), 453-9 PMID: 21457321

Cool Links

I see a lot of other blogs doing this, and I though it might be a good resource for those who read here. Here are some cool blog articles that I read this month.

Rogue Medic talks about how useful Epinephrine is when used to create a pulse during cardiac arrest, and its effect on the percentage of outpatients with brain damage.

MutantDragon has a great discussion on the history of the anti-vaccine movement, and where it is today.

Protein Evolution and Other Musings talks about bacterial proteins in eukaryotic cells.

Plos Blogs has an often repeated, but no less true, chat with media outlets about the nature and implications of individual study results.

SkeptVet had a similar article in the same vein.

Rule of 6ix has a really cool immunology article detailing new research on how influenza begins its initial infection and relates it to measles. It’s very accessible and educational.

Those are all the recent ones I remember for now, but I’ll start collecting these for the future and post them once and a while, enjoy!

 

Newsworthy: Is horse slaughter back on the menu in the US?

Image from PennState's Meatblogger.org

Well, the 5 year ban on funding dedicated to inspection of horse slaughter facilities has ended. The question now is whether the industry has been effectively killed, or if there is still a large enough market to find the funding and overcome the opposition.

Full disclosure: I have no problem with horse slaughter, and I also really like horses. The animals are subject to the same humane end as beef and poultry, and any objection to the consumption of horse products by those who enjoy other animal products is hypocritical. You may now choose to read or ignore the rest of this post if you wish, knowing that I’ll speak with this bias. I will however, make my points respectfully, and fully welcome reasoned and intelligent debate from anyone who disagrees.

Psych Your Mind has a great post discussing how we meat eaters manage to both love animals and eat them. A lot of it boils down to our separation of cow and steak, and how we perceive livestock animals as opposed to pets. Horses are unique in that they fall into both the work and companion categories, and it’s amazing to see how they can switch back and forth. This is similar to the many free chickens you find on Craigslist that no longer lay eggs, but “make great pets!”. The original owners clearly want them for production, but want no part in their non-economic use.

Google scholar shows a host of articles looking at the impacts of the ban that I’m not going to detail here. However I would really like to hear from readers in the comments, specifically readers opposed to horse slaughter and consumption! It’s difficult to find arguments not rooted in a religious, animal rights, or sentimental background, and I’m really interested to hear if there is empirical evidence that supports a slaughter ban. Whether it be based on export economics, public health (I have heard of food-borne illness concerns with horse meat), or potential detriment to other industries, I want to hear about it! So please feel free to comment and let me know where you stand on the issue!

 

 

Risk factors for companion animal (cats, dogs) vaccine reactions

I’m apparently still on this immunology kick, because I seem to be finding it everywhere. Heck, I recently learned that we’ve cured the allergic response to peanuts and eggs in lab mice. Check out the link, the author is hilarious and the material is interesting.

These two articles offer a great look at the overall prevalence and risk factors associated with vaccine-associated adverse events. The components within the vaccine that cause these events are the antigen itself, adjuvants, preservatives, stabilizers, and residues from the tissue culture used to grow the vaccine (Moore, 2005). Vaccine reactions are similar to any acute allergic reaction, and can present with a variety of mild to severe symptoms. The mild being lethargy, anorexia, fever, edema (generalized or local to the injection site), pruitis, uticaria (hives or wheals), and pain at the injection site; the severe being vomiting, dyspnea (labored or shortness of breath), and anaphylaxis. There’s a lot of information about when certain symptoms tended to occur at intervals after the vaccines were given, but any reaction that isn’t within the first 3 days is pretty much never going to be life threatening. If anaphylaxis is going to occur, it’s going to be immediately following vaccination.

The really useful information was the breakdown of risk factors that can be used for client communication. I’ve decided to discuss them here, broken down into cat and dog categories.

Image from meow-cats.com

First, let’s start with cats. I almost like these numbers more because you don’t have to take into account bias based on animal or breed size, as most cats fall into the <20 lbs category. Nonetheless you still have to remember that a 4 pound kitten does way only a fraction of that 5 year old chubby (BCS >5 on a 9 point scale) longhair it will grow to be.

So the first two risk factors require a little bit of thinking in context to explain the numbers. It seems that cats weighing 2-4 Kg (4.4-8.8 lbs) and approximately one year of age are most at risk compared to other weights and ages. The high numbers for these groups can be explained by the number of first encounter events that occur. If you’re recording vaccine reactions, you will record less in older age groups and higher weights (low weight under 10 lbs is going to be suggestive of a young age rather than a smaller cat), because if an adverse event occurred at a young age, either the animal is no longer vaccinated or steps are taken to reduce its risk (medication, strict scheduling, vaccine selection). That being said, just because the numbers are higher by circumstance, this information is very relevant in a clinical setting. Knowing the epidemiology of these events can help technicians at clinics determine when the discussion of vaccine reactions is “routine” or “protocol”, or when it really needs to be a time to educate the client. Vaccine reactions may need to be just a bullet point when Schrodinger is there for his 4th rabies booster and a discussion when he’s receiving his kitten series.

Sex and neuter status have a large impact on reaction risk as well. Intact males actually have a lower risk of adverse events than neutered males and spayed and intact females. Apparently, estrogen has an immune boosting effect, while testosterone has an immune suppressing effect. This benefits intact males when it comes to all allergic reactions (and possibly auto-immune disorders).

Here’s the big one, and the one clinics have the most control over. With each additional vaccine given in a single visit, the risk of an adverse event increases by 28% in cats. That’s huge. Any cases of severe anaphylaxis or death recorded in the study were preceded by the animals receiving 3 or more vaccines in one visit. So clearly the biggest thing any clinic can do to prevent adverse events (or at least severe ones) is to adopt a vaccination schedule that prevents multiple vaccinations from occurring within the same visit. This can be difficult as clients will not want to end up paying for multiple exams throughout the year, but with boosters outside of rabies, exams shouldn’t be necessary unless an annual or other scheduled exam is due. As far as specific vaccines being more prone to adverse events, the only suggestive evidence was when both FVRCP and FeLV were given within the same visit. This is explained by both having two concurrent vaccinations given, and also the theory that vaccines containing multiple antigens or covering multiple serovars (multivalent) are more likely to illicit reactions. Interestingly, while clients are often scared by the potential for vaccine caused neoplasia from the rabies vaccine, it was among the lowest reaction rates observed with the administration of a single vaccine.

Image from peteducation.com

Dogs had much more biased data within the age and breed groups because there is an obvious relationship between body mass and the potential for reaction. When looking at the dog population, a chihuahua can be as little as 6% of the weight of a bullmastiff, yet they receive the same 1ml dose of vaccine. This means that an 8 lb Chihuahua is going to receive proportionally 15 times more vaccine than a 120 lb bullmastiff. Not surprisingly, this causes a bit of inflation in the number of reactions in groups that are smaller in size, such as toy breeds and puppies. The highest risk group in size was 0-10Kg (0-22lbs) and the highest risk age was approximately 2 years of age (with higher rates for <2 than the rates of >2).

Just like I mentioned before when talking about cats, the greatest risk factor for reactions in dogs was the amount of vaccines given in one visit. The difference though, is how the large weight distribution in dogs makes this even more important. Small dogs (<10Kg) are similar to cats in that their risk increases by 24% with every additional vaccine administered that visit, while large  dogs (10-45Kg) increase their risk by 12 percent. All 3 dogs in the study that suffered fatal reactions received 4 or more vaccines at once.

Breed dispositions were difficult to pinpoint, as the suspected breeds are all small breeds which suffer a higher rate of reaction already due to their size. There is suspicion that dachshunds may be predisposed to allergic reactions in general, but so far the evidence is inconclusive concerning vaccines. Only the Lyme vaccine appeared to carry a higher risk than any other, showing again that, with the exception of neoplasia concerns, rabies does not carry with it any additional risk. Spayed and neutered animals, as in cats, are more susceptible to reactions; however the difference between intact and spayed females is much larger in dogs than in cats (where they are nearly identical). Dogs do seem to display an interesting trend where vaccine reactions are more likely to occur on the 3rd booster in a series, likely catching clinicians and clients off guard as they have received the first two without incident. This just states again that the puppy and kitten periods (and new patients) are of much more relevance when discussing vaccine reactions with clients.

The articles are both great, and contain an excellent statistical analysis of millions of animals. They provide a great overall picture of the epidemiology of vaccine-associated adverse events, and are definitely worth a read for both veterinary doctors and staff. Knowing a couple of the more important statistics can reassure the client and lend credibility to technicians that are responsible for discussing these issues.

ResearchBlogging.orgMoore, G., DeSantis-Kerr, A., Guptill, L., Glickman, N., Lewis, H., & Glickman, L. (2007). Adverse events after vaccine administration in cats: 2,560 cases (2002–2005) Journal of the American Veterinary Medical Association, 231 (1), 94-100 DOI: 10.2460/javma.231.1.94

Moore GE, Guptill LF, Ward MP, Glickman NW, Faunt KK, Lewis HB, & Glickman LT (2005). Adverse events diagnosed within three days of vaccine administration in dogs. Journal of the American Veterinary Medical Association, 227 (7), 1102-8 PMID: 16220670

Article review: Effects of early pregnancy diagnosis by palpation per rectum on pregnancy loss in dairy cattle

Image from UPenn

Just a short one here today. Not too much interesting going on in a study that supports the null, but the methods are great.
This study looked at the affect that one or two rectal palpations to determine pregnancy had on embryo viability. I can see why there would be a question, it seems like a highly invasive procedure when you’re shoulder deep in cow rectum and feeling for an amnion several layers of membranes away. But we tend to anthropomorphize, and many dairy cattle require minimal restraint for the procedure. Nonetheless, it does seem likely that there could be a negative effect on the embryo, especially when rupturing or crushing the amnion via rectal palpation has been a historical method of terminating an unwanted pregnancy in cows (before we started using PGF2α) (Romano, 2011).
The study did a great job of identifying factors that have created conflicting results in the past. Whether that was sampling bias, uncontrolled treatments (multiple people and techniques for palpation), or a lack of a true control. They took the time to show how each one of those shortcomings was corrected in this study, and I think they did a great job designing the experiment.
In the end it was surprising to see that there was no difference between the cows subjected to rectal palpation once or twice compared to the control. I didn’t expect to see a significant difference, but potentially a small one. The authors did warn that because this experiment was so controlled, the results may not be similar to every situation. Inexperienced personnel or different techniques could change the pregnancy rates in practice (the study employed a single veterinarian with >25 years experience). One difference they took time to note was the much lower pregnancy rate in dairy cows as opposed to primiparous heifers. The exact etiology of this is unknown, but is commonly found in dairy. The authors mention it as it played a role in their analysis of the two farms involved (other factors affecting rates between the farms were geographic area, rate of twinning, and breed of cattle).

Not especially exciting, but it’s always great seeing researchers identify a conflicted area and tackle it with strict methods/controls and a large sample size.

ResearchBlogging.orgRomano JE, Thompson JA, Kraemer DC, Westhusin ME, Tomaszweski MA, & Forrest DW (2011). Effects of early pregnancy diagnosis by palpation per rectum on pregnancy loss in dairy cattle. Journal of the American Veterinary Medical Association, 239 (5), 668-73 PMID: 21879969

Article review: Mechanisms of Viral Emergence

It’s funny how reading these articles is incredibly relieving for me. They confirm that I actually did learn and do remember principals and details from my classes. Today’s article comes from Veterinary Research, and discusses the mechanisms and variables involved in the emergence of a virus.

A viral emergence is generally defined as the appearance of a new pathogen for a host, such as human immunodeficiency virus (HIV)-1 for humans in the twentieth century. Viral re-emergence often refers to the reappearance of a viral pathogen after a period of absence, such as the periodic human influenza epidemics or pandemics.” (Domingo, 2010)

There’s a huge amount of information on viral evolution and mutation, a concept that (like everything else you haven’t specifically studied) I had greatly oversimplified. It was incredibly fascinating to read how viruses can recombine and splice gene segments from other unrelated infections, and the various pathways new genes can be created or introduced that allow viruses to jump host species. I’m not going to try to summarize all of those, the article explains them much better than I could, but there’s still a few broad topics in the paper worth discussing.

The concept of viral quasispecies is something I’ve never heard about. I’ve discussed viral serovars on here before, but I believe that term specifically refers to antigen variation. Quasispecies refers to groups of virus that are labeled and operate as one species (for example, Influenza H1N1) but contain different genomes. For example, if I get the flu this winter, the virus I am exposed to may contain several quasispecies, that are the same virus, but contain different genes. Now any deleterious mutations or reassortments will probably be wiped out by my immune system, but the ones with a fitness advantage will reproduce and take over. Here’s the extra interesting part, even if I had been infected with just one quasispecies, I could still shed several while I’m infected. There is so much mutation and variation in viral reproduction that I would be generating new ones as a single host.

Quasispecies are important in emergence because they are a major source of viral evolution. We identify the “wild type” gene amongst quasispecies as a distribution of genes that characterize that viral species (consensus gene); even though amongst different quasispecies they may be found in different places in the genome. This is where the existence of quasispecies propels viral evolution forward. When you mix up the genome so much, you can create mutations that change nothing in the functional portions of the genome, but create subpopulations that are fine tuned to conditions that may not yet be occurring. As an example, it’s been assumed that SARS was introduced to humans through Civet cats, when it was originally a virus transmitted by bats. Contact with civets is common in areas surrounding SARS outbreaks (where they are raised for food), where contact with bats is much less common. It is possible that there was a quasispecies subpopulation of SARS carrying a mutation allowing it to jump species to humans long before it was even introduced to civets. When the disease was contained to bats, this mutation has no fitness advantage, but it can sit idle until a change in the environment (higher infection rates in civets, civets brought from more rural areas, there are unlimited possibilities) gives it an advantage. This essentially allows virus to be proactive in its evolution. Instead of waiting for selective pressure, new genes are created spontaneously in the event that they may become useful.

Civet, image from healthjockey.com

The article continued to discuss different factors in emergence, primarily focusing on new host emergence, and brought it all together as an example of biological complexity. My personal favorite example for biological complexity is the realization that we’ll probably never fully understand the complete pharmacology associated with feelings of hunger and satiety. Alternatively you can illustrate this principal by asking someone to model the weather. The idea is that there are so many variables, all interdependent on each other, that it is pretty much impossible to trace all of the factors that led to an event such as the host change SARS made from civets to humans. They illustrate this by showing that even if viral variation is sufficient to promote a host change, there are numerous other roadblocks that have to be surmounted to allow it to take place (interaction with the new host, sufficient amounts of virus introduced to the system of the new host, fitness of the mutated virus, exposure to multiple quasispecies or serovars, future shedding of virus adapted to that host species, etc.). It’s a paradoxal idea, because we have been able to successfully model systems like these through the CDC and WHO, and we have been able to successfully model complex systems like the weather, even when there are countless interactions that we can’t even begin to measure.

Read this article if you have any interest in virology at all. I learned a lot, and it’s interesting and fluid reading if you have a basic understanding of cell biology.

ResearchBlogging.orgDomingo, E. (2010). Mechanisms of viral emergence Veterinary Research, 41 (6) DOI: 10.1051/vetres/2010010

Article Review: Epidemiology of Surgical Castration in the United States

I recently had a professor tell me that if I didn’t let them know if I made it into vet school, they would forever curse me with fat, in heat, Labrador spays for the rest of my career. I can think of few fates worse for a future veterinarian (though I did mention that the owners also had to have  no way to pay, and will forget to mention this until after the procedure). Today’s article is really cool and discusses the prevalence of ovariohysterectomy and orchiectomy (spaying and neutering, fixing, castration, gonad removal,de-nutting, whatever you prefer to call it) in the USA. It breaks the percentages down into region, animal species, animal breed, animal age, and enrollment in wellness plan from Banfield (animal health insurance).

Banfield Pet Hospital is an amazing organization for animal research because all of their records are computerized and kept in a central database (I should mention that the man who made Banfield what it is today is an OSU alum, go beavs). Because of this treasure trove of data, this study was able to get a sample size of over 300,000 cats and over one million dogs. While this represents less than 1% of the US pet population, its still a valuable amount of data, and we can reasonably assume that Banfield has a decent representation of the rest of the pet population that regularly visits private clinics. The article mentions that one of the only large differences is the mean age at clinics (Banfield’s is slightly lower). The numbers found in this study also line up well with previous examinations using distributed surveys to collect data.

I’m very proud to say that the Northwest region (making up Washington, Oregon, Idaho, and Montana) has the highest percentage of castrated cats and dogs compared to any other region (tied with the North Central region for percentage of dogs) according to the study. The region with the lowest percentage was the Southeast region (making up Alabama, Florida, Georgia, Mississippi, North Carolina, South Carolina, and Tennessee). That’s an area of the country I haven’t ever visited, so I can’t comment on cultural factors that may influence the decision to castrate pets, but clearly more outreach could be focused on that area.

The breed distribution is interesting, but doesn’t offer too much information for most breeds. In my own head I see the Labs’ and Retrievers’ high numbers understandable, as you can in some ways consider them “white-collar” or suburban dogs. This would be associated with a higher income and thus one less roadblock to castration. Pit Bulls can maybe be considered a “blue-collar” dog, but that can’t be the only reason their numbers are so low. I’m actually at a loss as to why the castration rate of Pit Bulls is so much drastically lower than all the others. It’s an obvious outlier. I myself love Pits and believe that in the right hands they make great dogs. But considering their stigma, low rate of adoption (and consequently high euthanasia rate), insurance liability, and higher risk, I do believe we should make castrating Pits a priority. I’ll definitely be looking for more literature that attempts to explain the demographics and other factors that create this problem. The second lowest group, Chihuahuas, is also interesting. Again, I’m not sure why the numbers for this breed are so low, but one factor may be that many Chihuahua’s are kept as indoor-only dogs, and that may reduce the motivation to perform the procedure, as the largest benefit is wasted on them (as seen by those owners).

I’m not surprised to see that mixed animals were more likely to be castrated, and I really have no problem with that. There aren’t too many unwanted animals that come from intentional breeding, and purebred animals generally don’t have trouble finding homes (pending behavioral issues). Responsible breeding doesn’t contribute to the pet overpopulation problem significantly, and leaving that option open to purebred owners is acceptable. With cats on the other hand, I’m happy to see the extremely high rate of castration. Cats are allowed to roam unsupervised much more than dogs, and we have enough trouble controlling the feral population without accidental pregnancies also occurring in animals that could have been easily castrated.

One rather frightening statistic was the percentage of dogs and cats from shelters that do not return for castration. This concerns me as in many cases the cost is free or subsidized to less than $50. In a private clinic you can pay upwards of $200, but this seems to be little incentive as 40-60% of animals are returned for the procedure when it is already paid for. To me, this is indicative that some of those owners will provide a low level of veterinary care for the lifetime of that animal, when they already haven’t taken advantage of a free procedure. This is pure conjecture however, and there could be a host of reasons that owners do not return. However, because the rate is so low, I would bet that there is some significant factor that is relatively consistent among owners who adopt from shelters, whether that be income (shelter’s are a very inexpensive option to get a purebred-looking dog) or attitude.

All in all, a good look at where castration is common, and where education and improvement needs to be made.  I do think that many PSA’s, advertizements, and advocacy campaigns are too often directed at groups that are already in agreement. Even looking the statistics from a PSA I made back in high school show that the primary people concerned with animal welfare are women over 35, and it’s clear that similar announcements are marketed at that group. New campaigns should focus on a new approach to educate people why castration is important, and maybe spend less time showing us pictures of sad puppies. Tell me why I personally should do it, because until it’s too late to change anything, there’s no reason I should think I’m part of the problem.

ResearchBlogging.orgTrevejo R, Yang M, & Lund EM (2011). Epidemiology of surgical castration of dogs and cats in the United States. Journal of the American Veterinary Medical Association, 238 (7), 898-904 PMID: 21453178

Newsworthy: Branding and Microchips

Veterinary ethics are especially touchy and complex because the general public often has strong opinions on every animal issue, including: euthanasia, animal welfare, animal rights, cosmetic surgery, private breeding, puppy mills, spaying and neutering, pit bulls, leash laws, animals as food, veal, genetic engineering, hormone use, vaccination, preventative care, training techniques, feral cats, dogs and livestock, licensing, service animals, classroom animals, TV animals, animal research, animal testing, animal waste, grazing on public lands, raw-food diets, alternative medicine, hunting, population control, use of animals in sports, no-kill shelters, captive wild animals, and a million others that people will vehemently defend their side on.

There are many on that list that I myself have strong opinions on, but its my responsibility as a scientist and my benefit as a debater to approach conflict on this issues as discussions, not arguments. I’m not always the best at it, but I pride myself on my willingness to be proven wrong. I like to think that when shown data, presented in a clear and unbiased way, I can base my decisions on all the information presented, rather than simply reject new opinions. Terry Etherton had a few great posts about communicating with non-scientists, and how there’s a need to reach out even when you receive a poor response. This isn’t just a scientist vs. the lay public thing, this is for anyone who wants to be part of a productive discussion of these issues. Everyone is entitled to an opinion, but unless we listen to each other and work toward middle ground, nothing ever gets done.

Image from howstuffworks.com

With my little editorial finished, lets jump into this article on branding and microchip use in foals.

“For animal welfare reasons, many veterinarians are currently promoting the method of implanting a microchip over the traditional practice of branding, while officials of major sport horse breed registries deny that branding really causes pain or stress to foals.” (ScienceDaily, 2011)

I’m a big promoter of microchipping, it’s hardly an invasive procedure, and causes little more pain than a vaccine. At my animal shelter, almost all microchipped animals we received were reunited with owners, as long as the chip data was current. They’re especially great for cats, who have a knack of removing collars with identification information when lost, and are more likely not to carry identification in the first place. The data shows that microchipped animals are much more likely to be returned home from shelters than non-microchipped animals. I haven’t heard much about microchipping in large animals until now, but I can understand why there’s a debate there.

Microchipping would be a difficult identifier in any large group of horses, as you need to get within inches of the animals, and there’s no way to simply view the identification. Ear tagging is unwanted aesthetically in horses, which leaves branding as a useful permanent mark. Freeze branding is an option the article doesn’t discuss, but it’s expensive, not always recognized by the state, and will be less visible depending on the animal’s color. The University of Veterinary Medicine in Vienna has done a study concluding that hot branding causes more long term stress from the injury, assuming that the short term stress is mostly due to restraining procedures the foals must go through to be microchipped or branded. The fact remains however, that branding in many ways is superior to microchipping depending on the management of the animals.

The counter argument to using microchips is further strengthened by the comparing the procedure to other common practices with foals. Castration, tail docking, and (in cattle) polling can be considered far more traumatic, and have similar debatable merits depending on the management strategy. The article also mentions a tradition component that it doesn’t elaborate on. Many county fairs have branding competitions and branding is often made into an event in rural areas, implying that the tradition of branding animals has a cultural component independent of animal welfare.

While branding may be more stressful for the animals, I do not think that microchipping is an adequate replacement as the only means of identification in large animals. The specific purpose microchips serve well in companion animals doesn’t translate into the same needs we have for livestock. Hopefully another solution will eventually be available, but for now it seems that the use of brands, ear tags, and microchips will be determined by management, not its effect on the animal.

Article Review: Ocular lesions associated with systemic hypertension in dogs: 65 cases (2005–2007)

The first of a bunch of articles I recently picked out of JAVMA was interesting because while I never got any readings without some form of anesthesia, I imagine that hypertension was extremely common in many of the dogs I saw at Lapaw Animal Hospital. Whether it’s a result of obesity, illness, or hospital stress, systemic hypertension is usually an indicator of some other problem, and therefore important in the analysis of the patient.

Image from Conrad Weiser Animal Hospital

The article is a bit confusing, because it goes into great detail the different potential causes of both hypertension and ocular lesions, and the significance of the data based on which was diagnosed first with each case. I began to lose track when on one hand they would mention that the data may be too biased to determine a cause and effect relationship between the two symptoms due to a preexisting condition, but then also said that those preexisting conditions had such a relationship.  It does seem clear that ocular lesions are promoted by the presence of hypertension in both dogs and cats, while the disagreements in the literature are mainly in how much one is indicative of the other. The relationship of hypertension correlating with ocular lesions in cats has varied from 50-100%, which tallied with the frequency of 62% in this case review. While these frequencies don’t prove any sort of direct relationship, they do support the evidence we do have that hypertension can lead to ocular lesions, and that if one is discovered in a patient, it’s worth looking for the other.

This is the first case study I’ve looked at in detail, and I’ll certainly be reading more as I move into veterinary medicine. It was really interesting to me how they selected cases, and how thoroughly they reviewed the significance of possible bias in each case. I absolutely understand why it’s so important, and the way each patient is presented changes how each symptom is portrayed in relation to the others, which makes the range of values for this specific correlation so understandable. Owners are much more likely to bring their dog into the clinic when seeing a clouded or irritated eye

Image from Bass Lake Pet Hospital

than hypertension would be found during a routine exam. Then you have to examine old clinic notes to see if other conditions led to either event, or to see if the veterinarian made the assumption that they were related, and though the situation was resolved, no lab work supports their theory. Some of the limitations  mentioned in the study were the fact that they lad a low sample of normotensive dogs with ocular lesions, and that diagnosis of hypertension is difficult due to situational stress interpretation in the face of blood pressure values and varied measurements within the “grey area” of test results. They also did significant analysis within the cases that took into account patients that were taking anti-hypertensive drugs for other conditions, but mention that those patients might have skewed the data, because there is no way to ensure that there was owner compliance in administration.

An interesting note is that all 5 dogs in the study that were currently taking Phenylpropanolamine either acutely or chronically were all hypertensive, supporting anecdotal evidence that it can promote hypertension. This makes sense to me, as PPA is controlled due to its potential use in creating amphetamine, and its inclusion in many prescription stimulants (Adderall, etc.).

All in all, a good article, and a good look at the relationship between ocular findings and hypertension. Though a large part of me does feel for those research assistants at the University of Wisconsin School of Veterinary Medicine who combed through thousands of patient files to find these 65 cases.

ResearchBlogging.orgLeblanc NL, Stepien RL, & Bentley E (2011). Ocular lesions associated with systemic hypertension in dogs: 65 cases (2005-2007). Journal of the American Veterinary Medical Association, 238 (7), 915-21 PMID: 21453181

Newsworthy: Ruminant Epidemics, Rinderpest and Goat Plague

I enjoy looking at animal science from a public health perspective, but I usually just think about it in terms of zoonoses and food safety, I hadn’t dwelled too much about animal health being directly related to whether or not someone eats tonight.

It was apparently a big deal when the United Nations announced that Rinderpest was eradicated just a few months ago. Rinderpest is credited with speeding the fall of the Roman Empire, and for the bankruptcy and starvation of many farmers/communities in 3rd world or war-torn regions. Now that the attempted eradication of Rinderpest was successful, veterinary experts are recommending that the next target be “goat plague.”

Pest de Petits Ruminants or “goat plague” is a viral infection related to rinderpest that affects sheep, goats, and deer (important as vectors for the virus). It’s pretty nasty and comes with a host of upper respiratory symptoms, gastrointestinal upset, and causes characteristic lesions on the mouth, lips, and gums. Mortality and rates of transmission are high, so I understand why it would be such an issue in prevalent countries. Additionally, goats are the “poor mans cow”, meaning that disease afflicting goat stock generally will affect people who can’t afford to lose a portion of their herd to an outbreak of disease.

Some of the economic returns associated with the eradication of Rinderpest are pretty amazing, so it seems like PPR would be a reasonable next step. No one can argue that helping impoverished parts of the world feed themselves is a bad cause, and the economic benefits of helping other countries be more successful are far reaching. Many times I have to explain to friends and acquaintances of the roles that animal scientists and veterinarians play in public health through the USDA, and that’s just a product of how little people stop to think how their food gets to Safeway. I found that I also don’t stop to think that while I look at disease prevention from a profits and and animal welfare standpoint, in other areas of the world it can be a matter of life or death for the farmers themselves.