vetmisconception

[vetmisconception]

Why We Need Animal Research Models

It seems this has become a popular topic again and I thought I would express my thoughts on it. As you can probably tell already from the title of this post I am pro-animal research. There are many reasons for me supporting animal research and I will lay out the facts as well as my general feelings on the topic. 

Overall, living organisms are vastly complicated and all parts and systems of the body are interrelated. The nervous system, brain and blood chemistry, organ and endocrine secretions, and  immunological responses are all one unit making it impossible to differentiate or predict how different diseases or treatments will effect one part of the body without looking at the whole living animal unit.

A drug everyone should be familiar with, Viagra, was original designed to treat pulmonary hypertension. Well during clinical trials on dogs researchers observed a surprising side effect of the medication… and as the story goes the rest is history. Now if this medication was not used in an animal model its other potential “side effects” would not have been observed. Now imagine if its side effect was more potent than an erection. Currently Viagra is commonly used in veterinary medicine to treat pulmonary hypertension and has just recently received the green light from the FDA to use it for this purpose in humans. It of course is still used for its flag raising effects in males. 

People have often argued that animals are poor models for human drug pharmacokinetics because our physiology is so different. Once again, to that I would have to disagree. There are more biological processes and anatomical similarities that link us to other species than what differentiates us from them. In fact we share 99% of our DNA with chimpanzees and 98% of our DNA with mice, a prominent laboratory research subject. It is estimated canine models share over 400 disorders ranging from endocrinopathies to neoplasia that mirror their human counterparts, making them an exceptional model for disease and treatment.

It is estimated that there are between 17-23 million animals used in research yearly. Of these animals 95% of them are rats and mice specifically bred for research, only 4.25% are rabbits, guinea pigs, sheep, fish, frogs, insects, and other species. And even to a lesser extent 0.75% of the animals used in research are cats, dogs, and non-humane primates. In general researchers try to use alternative models for their research whenever possible, but animal models are by far the gold standard. 

Additionally, animal research models benefit veterinary patients as well. Animal models have helped develop vaccines to fight diseases such as rabies, distemper, feline leukemia virus, canine infectious hepatitis virus, and tetanus to name a few. Animal models have also led to the understanding, prevention, and treatment of heartworm disease. 

Other examples on how animal models have benefited man-kind:

Herceptin – a humanised mouse protein – has helped to increase the survival rate of those with breast cancer; it could not have been attained without animal research in mice.

Research on animals led to the development of Highly Active Anti-Retroviral Therapies (HAART), AIDS is no longer the death sentence it was 30 years ago.

While Fleming discovered penicillin without using animals, he shared the Nobel Prize with Florey and Chain who, by testing it on mice, discovered how penicillin could be used to fight infections inside the body.

Animal research is responsible for the development of asthma inhalers; asthma still kills around 2,000 people in the UK every year.

Animal research has helped develop modern vaccines including those against Polio, TB, Meningitis and, recently, the human papillomavirus (HPV) which has been linked to cervical cancer.

The development of Tamoxifen in animals led to a 30% fall in death rates from breast cancer in the 1990s.

The 450,000 people in the UK suffering from Type I diabetes rely on Insulin – which was developed through experiments in rabbits and dogs.

Smallpox has been eradicated from Earth thanks to research in animals.

So while animal testing may be an uncomfortable idea, it is definitely necessary. Next time your doctor sends you home with some antibiotic, just say a small thank you to all those mice that have contributed to science and made the world a better place.

A monument to all lab mice used for DNA research. - Novosibirsk, Russia

Sources:

The discovery and development of Viagra

Dog models of naturally occurring cancer

Understanding Animal Research

California Biomedical Research Association

[vetmisconception]

Hello Fellow Followers!

As it is pretty apparent I have been swamped lately! I totally apologize for my absence on this blog, but if you want vet related articles/ or to just keep up with me on a more causal blog you can follow my personal blog over at hoovesandheartbeats!

Hopefully I can think of a good topic soon, research it well, and bring you guys another amazing post in the near future. Until then come visit me at H&H or have a look around at my older posts. 

Thanks! You guys are great!!

[vetmisconception]

Safe From That

Misconceptions #50: You can get what from your dog?

Zoonotic diseases can be scary things, and there are many in existence, but are there some that we blame on our innocent pets that we shouldn’t? Unfortunately there are many misconceptions surrounding some common parasitic organisms that the general public fall prey to and end up blaming these illness on the family pet.

Pinworms:

Pinworms have been blamed on the family dog many times. I personally know of a case where a MD told a family to get rid of a dog because it gave their child pinworms. So what are pinworms? Pinworms are a nematode from the family Oxyuridae.  These parasites inhabit most domestic birds and mammals, but rarely fish. Curious note, pinworms are extremely host specific and there are no species that infect dogs or cats. This means two things: 1) the family dog/cat did not give anyone in the family pinworms, and, 2) even if dogs/cats had pinworms they still would not be able to pass them on because of their host specificity. Which means, if little Johnny comes down with pinworms, he got them from some other human. 

Giardia:

Giardia, the heart-shaped parasite with a smile. Giardia is of the family Hexamitidae and is a flagellated protozoa that resides in the small intestines. A person/animal becomes infected with Giardia after ingesting water that has been contaminated with fecal matter containing Giardia cysts. Giardia’s reputation of being a major zoonotic player has more recently been questioned thanks to genomic sequencing. According to recent studies Giardia seems to exist in different “assemblages” or subspecies per say.  These various assemblages vary in their ability to infect different hosts.  Dogs mainly have assemblages C and D, while cats have A1 and F.  Humans are infected with A2 and B.  Dog strains are not known to infect cats, just like cat strains are not known to infect dogs.  Through genomic sequencing it appears that humans are infected by other humans and zoonotic transmission (from dog/cat) is rare, if it occurs at all.

Tapeworms:

While tapeworms are technically transmissible to humans “from” pets this is a very rare and unlikely event. A person would first have to be unfortunate enough to ingest a flea and then that flea would also have to be infected with a tapeworm larvae. The ingestion of an infected flea is the only way a human could contract the canine tapeworm, Dipylidium caninum. When transmission does occur, it is usually children and the infection is harmless and easily treated. However, there are other species of tapeworms humans can contract from the genus Taenia that range in their severity, and these can be acquired from ingesting undercooked meat.

Lice:

Lice are another parasitic organism that are extremely host specific. In fact these buggers are not just host specific they are also location specific. Body lice for an example can not stand to live near the scalp/skin because it is too warm for them, and head lice don't inhabit the pubic area because their appendages can't grasp the course hair. Each lice species has specifically adapted appendages to survive on its intended host. 

Mange:

Mange is caused by different species of Demodex mites. Once again this is a host specific organism and dogs, horses, cattle, swine, goats, cats, and even humans are commonly infected with this follicular mite with out issue. Dogs can develop mange though when they are puppies or when they become immunocompromised. Human can also develop generalized demodecosis when they become immunodeficient.

References to expand your knowledge:

Foundations of Parasitology, 8th ed.

Is Human giardiasis caused by two different Giardia species? Jerlstrom-Hultqvist, Ankarklev, and Svard. Gut Microbes. 2010 Nov-Dec; 1(6)

Multilocus Genotyping of Human Giardia Isolates Suggests Limited Zoonotic Transmission and Association between Assemblage B and Flatulence in Children. Lebbad, et al. PLOS Neglected Tropical Diseases. 2011 Aug.

CDC Info on Dipylidium caninum

CDC info on Lice

Info on Demodex

[vetmisconception]

I read your post about the cost of veterinary school. I'm really concerned because I would at least like vet school to be an option for me, but I can't go if I have to take out $150,000 in loans. I am the first person in my family to attend college, and I am in my third year with only $4,000 of debt. While this sounds minuscule, it is a lot of money to me, because I mostly support myself. (I have a part-time job outside of class and I barely make enough for daily necessities, let alone loan...

Well, cost is definitely a concern, and you have a right to be concerned.  I don't think loans of any kind should be undertaken lightly.  There is certainly a huge cost associated with vet school more so than some.  Your in state school is usually your cheapest option (except if you're unfortunate and live in Pennsylvania, New York, or Massachusetts).  The newer "private" schools like Western, and the Caribbean schools also come with a hefty price tag. 

I can't really give you a very positive answer because unfortunately thoses that graduate vet school with little to no debt are those that are either A) married or B) have extremely wealthy parents, BUT there are options.

The Army has a Vet Corps and the HPSP scholarship can be applied for your first year of school and you start receiving benefits your second year. It is a pretty sweet deal, but you do have to commit yourself to 5 years of military service. In return though, you graduate debt free and have a job with awesome pay and benefits. This scholarship though is highly competitive (for obvious reasons)

Many schools offer a variety of scholarships, though these are normally small amounts $150-$2,000. Drug companies will also offer a variety of scholarships throughout the year, that the school will notify students about (but all these are dependent upon you already being a student)

Many people say you can't work through school, but really, I think if you are smart and determined it would be possible. I don't think I would of been able to first year just because I was adjusting to the school studying thing, but second year (the "hardest" year) my grades improved immensely and I had tons of free time (lets just say there was more room for studying if I wanted to participate in that activity).

There are several program after school for repaying loans, such as public service loan forgiveness, but I would not bank on these programs still existing in the next 10 years.

What I can tell you though, is most people going to vet school and graduating are faced with the same reality.  We are all faced with a fair amount of debt, some more than others (there is a guy in my class that already has 300k in debt; thats what a fancy private UG gets you), but from the vets I have talked to the payments are manageable. I do know of a practice owner that is in his mid 50's that is still paying off school debt, not promising, but at least I know I am not going to be the only fish in the pond doing so.

I don't really know what to tell you, other than, if you want to graduate and start making bit bucks, engineering is probably a good career (sometimes I wish I picked engineering).

[vetmisconception]

Playing Goldilocks

Misconception #49: This form of food should only be fed because...

Each form of diet from dry to wet offers benefits as well as disadvantages.  Here I hope I offered a overview of what general components are found in eat form of a diet as well as general pros and cons with each (without going into detail about each ingredient).

The Kibble (Dry Food)

This group of food includes baked kibble, and biscuits both of which are prepared in a similar manner. These diets are produced through a process called extrusion. This process involves mixing all the ingredients together to form a dough, which is then cooked under high pressure and temperature (1).  Extrusion causes rapid cooking of the starches within the dough which leads to increased digestibility and palatability. Some minor loses of vitamins can occur during the cooking and storing process so these nutrients are added back in by the company. The heat used by the extrusion process helps to sterilize the product and decreases the moisture content which aids in the prevention of bacterial and fungal growth. A variety of ingredients are commonly used in dry kibble like cereal grains, various meats, vegetable fats/oils, and vitamin/mineral supplements.

Some advantages of dry food include the reduction of plaque and calculus accumulation on the teeth and safety of the food (heat treated for bacteria/fungus) (2,3). A potential disadvantage to dry kibble can be improper processing which reduces nutrient availability and content.  Poor quality foods often are detected by having low digestibility and thus high stool production, where a high quality dry kibble from a company that handles its ingredients properly will maintain its digestibility and produce low stool amount (more on pet food quality and classification later).

Wet Foods

I am only going to discuss wet foods that are complete and balanced and are designed as the primary food source.  These products can contain one or two types of muscle meat or some other animal byproducts with vitamin and mineral supplementation to make the meal nutritionally complete. A disadvantage to feeding wet foods is that the diet provides a higher amount of metabolizable energy than required by cats and dogs so it can easily lead to obesity.  An advantage to feeding wet foods in cats is that it ensures the animal is receiving adequate hydration which reduces the risk for lower urinary disease. These products are also sterilized and sealed which allows them to have long self-lives without spoilage.

Semimoist Foods

These diets frequently contain cereal grains, fresh or frozen meats, fats, and simple sugars.  Several methods are used to preserve these foods such as salts, simple sugars, glycerol, and corn syrup all of which are designed to lower moisture content and reduce bacterial growth (4). Some preservatives are used to prevent the growth of fungus. The amount of carbohydrates in semimoist diets is comparable to dry diets, however these are usually provided only in simple carbohydrates. Semimoist foods are often extremely palatable to canines due to the simple sugars which can lead to over eating and obesity.

Some References to enhance your viewing pleasure and knowledge base: 

(1) The effect of extrusion on the national value of canine diets as assessed by in vitro indicators.

(2) Dog biscuits: An aid in canine tarter control.

(3) Diet and periodontal disease in dogs and cats.

(4) Water activity: the key to pet food quality and safety

Canine and Feline Nutrition 3rd ed. Chapter 17

[vetmisconception]

Is it hard for vets to find jobs?

Since I am still in school I have not started the job hunt, so I can only pass on information that the AVMA has published about the veterinary professions job outlook. 

According to a report published in April 2013, in a study conducted by the IHS Healthcare and Pharma and the Center for Health Workforce Studies they found there there is currently an excess capacity of veterinary services in the United States. The report found that the supply of veterinarians in 2012 (90,200) exceeded the demand of veterinary services by about 11,250 full-time vets.

This does not mean that veterinarians where unemployed, but that employed veterinarians where being under utilized and their service potential not fully being reached due to lack of demand.

The study noted that if the problem is not corrected it is likely to persit into the foreseeable future. As a student I can say that I don't think the AVMA is doing anything to curb this problem, if anything they are just aggravating it by granting accreditation to three more vet schools here in the United States.

According to the AVMA in 2013 most new grads found jobs. 

From what I have observed the job market is fairly stable (at this time), but pay is variable, and you can't always be picky about the area of medicine you want to enter upon graduation.

[vetmisconception]

What's In A Name

Misconception #48: Can't believe everything you read

This is part of a food series.

To start out talking about pet foods I thought it would be good to talk about what different portions of pet food labels stand for.  Certain components of a pet food labels act as legal binding documents between the pet food producer and the consumer. So what components are these?

Designator: States what species the food is designed for (Cat Food, Dog Food)

The Product Name (but not what you think): The percentage rule

If a Product name includes the buzz word  “All, 100%”: it is 95% that meat

           (example: 100% beef diet)

Just the Meat name = 70% that meat

          (Beef diet)

Buzz words of: “Dinner, platter, formula, recipe, entrée.” =25% that meat

            (Potato & Beef formula)

Any diet that includes “with” = 3% that meat

          (Sweet Potatoes with beef)

“Flavor”= ≤ 1% that meat

            (Beef flavored)

Nutrition Statement:

Designates which life stage the diet is targeted for, and if it meets AAFCO standards

Statement like “Complete and Nutritious��, “For all life stages”

Growth

Maintenance

Gestation & Lactation

Complete for all life stages

Additional Statements

Natural: this designation means the diet was derived solely from plant, animal, or mined sources. Many natural diets have added vitamins and minerals which are synthetic.  This is a legally defined term.

Organic: The USDA has not yet established its certification program to pet foods but AAFCO does recognize the use of the word with USDA standards. This is a legally defined term.

Holistic: The claim is that the product is made from pure ingredients that the consumer would eat.  This term is not legally defined and recognized.

Pet Treats:  Pet treats do not have to have any nutritional statement listed.

[vetmisconception]

Hi. I was wondering if you could tell me anything about heart worm prevention medication? Like how it works, pros and cons of it, side effects, how long it lasts, and anything else that might be important. I've been doing research on it but haven't had much luck, and I've been told different things about it by different people. Some say its good, some say it will kill your pet. Any help would be greatly appreciated. Thank you.

This is an excellent question!! So thank you for asking. 

First a little bit about the actual parasite: Heartworms are a microfilariae organism that is transmitted through mosquito bites.  Mosquitos become infected after engorging themselves on an infected dog. The mosquito while ingesting blood it is also taking in microfilariae from the infected dog.  After a period of time the microfilariae mature in the mosquito and are ready to infect another dog. Once inside the dog they make their way to the heart, lungs, and associated arteries where they mature into adults, this process takes about 6 months.  Adult heartworms in dogs can survive for up to 7 years!

Heartworm prevention works by killing these microfilariae before they have the chance to mature into adult worms. Once they become adults the only current treatment for heartworms is only available for dogs and is it extremely painful, and expensive.

Heartworm prevention is key to protecting your pet from developing heartworm disease. The good news is prevention is available in a variety of forms for both cats and dogs. Many different companies have products that are either chewable treats, tablets, to topical treatments. These all act on the parasite the same way though by targeting the microfilariae.  The great benefit of these products is they also commonly come combined with other parasite treatments such as intestinal parasite, fleas, ear mites, etc, so you are getting a good value for your dollar.These products are all given monthly and it is the owners responsibility to remember the pets schedule and to maintain it. The biggest failure in heartworm prevention is the client forgetting to give the prevention on a routine bases. There is also a six-month injectable form of heartworm prevention available for dogs only.

These products have an extremely high safety margin on them, and are commonly used in all veterinary practices. Good standard of care dictates before starting heartworm prevention your veterinarian will first test your pet for the presence of heartworms. After a negative test your vet will want your pet tested yearly.

What is the benefit of having yearly negative heartworm tests and proof that your pet is current on heartworm prevention? Well I am glad you asked.  If for a chance there is a failure, and your pet becomes infected most companies will cover the cost of heartworm treatment. Now you are wondering why would a pet become infected with heartworms if it was on heartworm prevention? Well that’s another good questions, some heartworms seem to be developing a resistance to some products. This however does not mean that heartworm prevention is infective or waste of money. These cases are still rare, and prevention is key to preventing the disease.

What people may be getting confused about is heartworm treatment. Treating heartworm disease, once the parasites mature into actual adults becomes a little bit more risky, it’s painful to the pet, and it costs a lot more money. Treatment for heartworms though is relatively safe and successful if the owners comply with the veterinarians instructions. Complications can follow heartworm treatment if an owner does not strictly abide by the veterinarians instructions. There is no treatment available in cats, and infection that presents with clinical signs in cats often quickly progresses to death.

For more information the American Heartworm Society’s Website if phenomenal and you should check it out!

I hope this helps you out. Overall heartworm prevention is awesome, every dog and cat should be on some form of it.

[vetmisconception]

Stick with the Science

Misconception #47: “Natural” products have no side effects and are healthier for my animal.

The other day a friend posted an article to her facebook discussing the amazing benefits of dichotomous earth as an anthelmintic treatment and the article discouraged people from using conventional dewormers because they were “poisons”, needless to say I was irritated.

First off, there are so many “natural” “homeopathic” treatments I could write a book discussing each one, so for the sake of my friends post I will focus on the use diatomaceous earth (DE) as an anthelmintic treatment.

So what is DE? Well DE consists of fossilized diatoms, which form a soft siliceous sedimentary rock.  DE is then used commercially from everything from toothpaste, slug repellent, to cat litter. The theory behind using DE as an anthelmintic is that the sharp edges of the diatoms essentially cut the worms and injure them, causing them to die (I guess there is no worry about the animals GI mucosa).

Unfortunately, DE is not a harmless “natural” substance.  If the fact that there is no scientific evidence to back up DE’s claim to being an anthelmintic is not enough possibly its other negative consequences will be. Because DE is made out of silica (which is essentially glass) it can cause micro lacerations to the GI. Additionally if DE is inhaled it can cause silicosis (which let’s be honest if you are putting this in an animals feed, you can bet the animal is inhaling it).  There are also reports of DE being linked to colic in horses.

Ivermectin though is a naturally occurring product produced by the natural fungus Streptomyces avermectilis. Ivermectin is what is considered a conventional dewormer. Unlike DE, Ivermectin has been rigorously tested for safety, side effects and efficacy! Ivermectin is also widely available at all your local feed stores so it is easy to find and purchase.

“Natural” is not always healthy, and “natural” does not come consequence free. Products labeled "natural" can be just as toxic as anything else. If no toxicity profiles have been preformed and if there is no legitimate scientific evidence backing up a products claim there is no way knowing if that product is safe to administer to your animal.

I have included links to scientific articles for your viewing pleasure:

The effects of DE on parasite infected goats

Effect of DE as an anthelmintic treatment on internal parasites and feedlot performance of beef steers

Evaluation of DE as an adjunct to sheep parasite control in organic farming

[vetmisconception]

vetmisconception turned 1 today!

[vetmisconception]

For several months, these 'animal rescuers' stalked, harassed, verbally abused, cyberbullied, and damaged the reputation of Dr. Shirley Koshi. They...

For those of you who don't know about this recent issue here is some more information:

New York Times Article about what lead to Dr. Shirley Koshi's Suicide

Vetsbehavingbadly: Friend's account of what caused Dr. Shirely Koshi's suicide

Cyber-bullying and harassment seems to be a growing issue these days as people find power with their anonymous shields.  This empowered voice though should never come at the cost of a life.  Above is the link to a petition to help apply pressure to the NYPD to peruse the activists groups that engaged in slander, harassment, libel, and cyber-bullying against Dr. Shirley Koshi that ultimately led to her death. 

Dr. Shirely Koshi's own account of events prior to her death

[vetmisconception]

Misconception #46: That can never happen

Who's familiar with the movie Contagion? Well the opening seen (the clip shown) perfectly demonstrates how some really nasty viruses can potentially be transmitted. 

Heniparavirus is a genus which includes 3 known species of viruses all of which use fruit bats as reservoir hosts. Hendra virus and Nipah virus are two members of this genus which have veterinary importance. These two viruses are highly zoonotic and have a high mortality in humans. In addition to their human toll, Hendra virus (located in Australia) also poses a high mortality to horses. Nipah virus (located in Asia) infects pigs and presents with neurological and respiratory signs. The virus is controlled by culling infected individuals.

These viruses are members of the family Paramyxoviridae and are enveloped ssRNA viruses.

- What we should take away from this is 1 person could of prevented an outbreak by washing his hands with soap and water and  in doing so destroying those weak little enveloped RNA viruses.

[vetmisconception]

Misconception #45: It's just a theory

Top 5 misconceptions about evolution: A guide to demystify the foundation of modern biology.

Version 1.0

Here is an infographic to help inform citizens.  From my experience most people who misunderstand evolution are actually misinformed about what science is and how it operates.  That said, here are five of the biggest barriers faced when one explains evolution - I have faced these and they are documented in the literature.

I hope you can build on my work and improve the communication between the scientists and the public.

Want to do more?  If you want to donate to the cause of science education I suggest the National Center for Science Education http://ncse.com, your local university, or an equivalent organization.  Volunteering at schools and inviting scientists into classrooms are two ways to encourage an informed society.  Attend hearings if school boards start questioning evolution’s role in public curriculum.  Raise a storm if anyone tries to ban science.  Plus, it never hurts to reblog a well made evolution post. Thank you followers for all your support! Love,  molecularlifesciences.tumblr.com

[vetmisconception]

Bugs fighting Back

Misconception #44: Animals are to blame.

The debate about who is responsible the most for contributing to the new developing problem of antimicrobial resistance I think is a lot like arguing which came first; the chicken or the egg.  Yet the debate wages on and often time the finger ends up pointing at veterinarians. 

In 2013, the Center for Disease Control (CDC) put together a comprehensive report on the current state of antimicrobial resistance and how the stewardship of those drugs can be improved. In that report the CDC did heavily criticize the use of antibiotics in agriculture, but they went on to name hospitals as the largest source of the problem. 

I have many opinions about this issue, many of which I am sure you are not interested in hearing; but I think many people feel about this issue the same as they do about climate change.  For a moment they are worried, then they feel like action should be taken, and seconds later they remember they have chocolate ice cream in the freezer. Everyone feels this is a problem for someone else to handle, after all how can one person make a difference when everyone else is doing it. 

Anyways, read the report if you want, it's extremely interesting.  For those of you who aren't into reading very long reports, here are some cool graphs the CDC included. 

Why this issue should be important to you:

Source: CDC

Great illustration explaining how drug resistance can develop within communities. 

Source: CDC

There are so many other really cool graphs and illustrations so I really urge all of you to read the report or at least donate 20 minutes to glance through it.  The writing is straight forward and easy to understand, it even includes a glossary at the end! (what more could you ask for?)

[vetmisconception]

250 Followers

Whoop! Thank you everyone who has been following me from the beginning and for those who have joined me along the way!

If you are new to my blog, a bit about it:  There are a lot of misconceptions surrounding animals, medicine, the profession of veterinary medicine, vet school, and science in general.  I like to blog about random topics in these areas.  Sometimes I am inspired to do a post based off an encounter I had that day, other times I will do a post based off a lecture or as a way to study.  If there is ever something that you have "heard" that you would like me to write about let me know and I will try to get to it.

A little about me:  I am a second year veterinary medicine student, who is interested in equine medicine, zoonotic diseases, and parasitology. I find almost all areas of science extremely interesting though, and If I wasn't a vet student, I would probably be an astrophysicist. 

Have fun and always continue learning!

[vetmisconception]

To be Bigger Than a Walnut

Misconception #43: A horse's brain is the size of a walnut.

Many people believe horses to be unintelligent due to their herd mentality or their flighty nature.  Even more like to use the misconception of the walnut sized brain to explain away a horse's nature (horse people do this the most). So what is the truth? How big is a horse's brain?

Horses' brains are between 400 - 700 grams depending on individual variation; walnuts weigh about 15 grams.

Additionally the size of the brain is not the only factor that contributes to an animal's intelligence. The cerebrum has a folded appearance called the cortex. The cortex is made up of folds (gyri) and grooves (sulci). The folds and grooves increases a brain's surface area allowing more brain to fit into an area; grooves and folds are proportionally associated with intelligence. 

Horse brain, showing gyri and sulci

Horses primarily learn based on conditioned-response (but so do many, many other creatures including humans), they are also able to form categories, generalize, and conceptualize. 

And because there should be a picture of at least 1 live horse in a post about horses =)

[vetmisconception]

Drugs not Hugs

Misconception #42: Local anesthetics block only pain. 

Pain management is a growing area in veterinary medicine, and local anesthetics are one way to manage pain in hospital. 

Local anesthetics block all nerve function not just the pain fibers. These drugs work by inhibiting active voltage-gated sodium channels, which prevents axon action potentials.

Pain is generally the first sensation lost from a local anesthetic followed by cold, warmth, touch, deep pressure, and finally motor function being the final sensation to go.  These sensations will then return in the reverse order. The size and myelination of the nerve axon determines the order the nerves are blocked and thus the order the sensations are removed.  Small unmyelinated fibers of sympathetic neurons are the first to be blocked and are last to regain their function, while larger myelinated fibers that control motor function are last to be blocked and are the first to regain their function.