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Plant Sciences, Zoology & Evolution / Re: Why vaccinate a dog every year?

« on: 20/03/2018 03:12:02 »

(Do I really want to talk about vaccines over the internet?...)




Hi itadiki,

I'm not sure where in the world you are, so please keep in mind that it is really difficult for me to give an answer that applies across all countries. If you want an accurate answer for your particular situation and location, it would be best that you speak to your local vet directly.

The answer will vary depending on what diseases are prevalent (common) where you live (or travel to), and what registered vaccines are available to veterinarians in your country. Even within a given country, there may be variation in vaccination recommendations since some diseases occur more commonly in some areas than others, depending on factors such as geographical variation, urban vs. farm environment, and socioeconomics.

For example, I live in a part of Australia that is urban, and the main infectious diseases of concern in dogs that can be vaccinated for are parvovirus ("Parvo" gastroenteritis), adenovirus ("hepatitis"), distemper virus ("distemper"), parainfluenza virus ("kennel cough" or "canine cough" complex) and Bordetella bronchiseptica bacteria ("kennel cough" or "canine cough" complex). So these are the diseases that our local recommendations are based on. Some more rural and farming areas may also have increased risk of Leptospira bacterial infection (leptospirosis), so vaccination recommendations will reflect that. I’m less familiar with rabiesvirus recommendations, as we don’t have rabies in Australia, but it is another common routine vaccination performed in other countries.

So… The easy part of the answer is that the available “kennel cough” or “canine cough” vaccines all have a short duration of immunity, of approximately one year, so that is why that part of the vaccination program is always recommended as a yearly booster. Dogs that lapse on these boosters are at risk of becoming ill themselves, and shedding disease to other dogs.

The other part of the routine vaccination protocol (the “C3” – parvovirus, adenovirus, distempervirus) has been subject to some variation in vaccination recommendations in recent years, with the development of newer vaccine products; and more recently, a growing public phobia of vaccines. Traditionally, the standard recommendation was an annual vaccination booster for any of the available brands of C3 vaccines. However, there are CERTAIN vaccines for C3 now available and registered for a three-yearly vaccination program. The key word here is “registered”, which means that the product has been clinically tested to scientifically demonstrate both safety AND effectiveness (efficacy) when used according to the recommendation on the label. It also means that the manufacturer of the vaccine will accept liability in the case that the vaccine did not provide adequate protection. Using a registered 1-year vaccine product as a three-yearly vaccine is called “off-label” or “extra-label” and does not carry the assurance that the vaccine will actually be protective over that whole 3-year period. It is best to discuss with your vet about which vaccine options are available to you in your area.

All of the three viruses that the C3 vaccine protects against are deadly, extremely difficult and costly ($1000s) to treat, with no guaranteed survival even with intensive treatment, and often result in heartbreak for the family of the pet, and for the vet who has to watch an animal die despite their best attempts to save it. This is why you will find that all vets recommend vaccination against these viruses. It isn’t to make money, as the internet will have you believe. Vaccines cost owners less than 5% of the cost to treat parvovirus, so it would be a pretty stupid way to try to get rich. You’ll find that vets would just rather not have to see another sick dog die from such horrible, but preventable diseases.

In the case of an owner who is extremely concerned of vaccinating their dog, or a (rare) dog that has previously had a vaccine reaction, vaccination titre tests are also now available. These test the level of antibody in the blood stream, to help predict if the dog is currently protected by a previous vaccine, or not. Unfortunately, there are no scientific studies to date that indicate what level of titre is required to indicate that a dog is protected (immune). So, you will get a result, but that number won’t tell you what will happen if the dog is exposed to the virus. The other downside is that these tests are relatively expensive to run and may not be available in some locations. But it is certainly something you can discuss with your vet, if you are not concerned about paying the extra for testing.

The prevalence of disease may also affect vaccination recommendations in a given location, since the risk of exposure and infection is higher in some areas that in others. For example, some towns are known to be “hot spots” for parvovirus, due to low vaccination rates, and a high number of unvaccinated dogs mixing. Disease outbreaks are another situation when the risk of infection is higher than average. Consequently, the recommended frequency in “Town A” and surrounds may be higher than in “Town G” and “Town M”.

Herd immunity. This is basically when a certain frequency of immunity is required in a population to provide protection across all members of that population. The typical frequency required for this is usually high (>70%) but even higher for diseases that are highly pathogenic or highly contagious. When the level of vaccination drops in the community, it puts the entire population at risk of outbreaks and results in large amounts of virus/bacteria in the environment. Some members of the population cannot be vaccinated due to genuine reasons such as age (eg. newborns, geriatric), or problems with the immune system, and they rely on those healthy enough to do their bit for the team. This goes for both dogs and humans.

Human health. Some health recommendations for pets take also into account the risk of disease to humans. Zoonotic diseases are those that can transmit from animals to humans and cause disease. The best example of this would be rabies, which is deadly in both animals and people, and is transmitted through bites and saliva. My understanding is that it is legally required to vaccinate dogs and cats yearly against rabies virus in some countries where it is endemic (widespread). This is to not only protect the pet from life-threatening disease, but to protect humans who would be at risk of death if the pet becomes infected. Because, legally, human health often has to take precedence over animal health, an unvaccinated pet that bites a human may be required by law to be euthanised and their brain submitted to a lab for rabies testing. This is a very unfortunate, and sadly not uncommon, consequence for both the pet and the owner who has chosen not to follow vaccination recommendations.

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Plant Sciences, Zoology & Evolution / Re: Can Indian and African elephants interbreed?

« on: 27/08/2017 11:07:01 »

I'm a bit surprised that those two species have been able to interbreed at all (according to that reference) given the extensive geographical isolation and taxonomical difference. They are not even the same genus.

I'm not sure if there are any specific genetic factors that would make their offspring incompatible with life. However, so much has to "go right" for an elephant between conception and adulthood for it to succeed, that I'd think that any suboptimal physiological factors would surely have to disadvantage such a hybrid (near enough is probably not good enough). For example, I would wonder about the effects of:
- different foetal size vs. placental blood supply
- different foetal energetic/nutritional requirements vs. maternal requirements and intake
- different foeto-pelvic proportion
- slightly different gestational period
- different composition and volume of the milk and colostrum
- different growth rates and possible increased susceptibility to disease (eg. elephant endotheliotropic herpesvirus)
- different height ratio between the calf and the mother's teats
- social factors (eg. maternal acceptance, acceptance into the herd)
- dental malocclusion from overcrowding
- skeletal abnormalities combined with an enormous body weight

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Physiology & Medicine / Re: The more you eat, the hungrier you feel - do you agree?

« on: 05/07/2017 15:52:54 »

I have two working theories on this: the first slightly more established, the second more of a "watch this space". Here goes:

1) Hunger isn't as simple as a measure of the volume of food consumed, but also of the quantity of particular nutrients. I strongly subscribe to the idea that the body seeks to obtain any nutrients that it is deficient in, although sometimes it is misguided on what it must eat to obtain said nutrient. An example of this is when severe nutritional deficiencies can lead to "pica" (the abnormal craving and consumption of non-food items). It appears that when the deficiency of nutrient is severe enough, the body is willing to have a go at eating ANYTHING to try an obtain that nutrient. Similarly, pregnant females are frequently reported to crave very unusual food items during pregnancy; perhaps due to extremely high nutrient requirements for both mother and foetus.

In Western society, there are plenty of easy-access food products that border on the definition of "non-food items" and are quite low in their nutrient content (other than fat, salt and sugar). Therefore, if a large part of your diet comprises of such low nutrient items, you are going to end up deficient in essential nutrients such as proteins and vitamins. In order for your body to then find those nutrients, you are going to have to eat even more food, until the required nutrients are obtained. If you eat highly nutritious foods (eg. vegetables and whole foods), you may be able to correct the nutrient deficit while ingesting a relatively low number of calories. But if you eat nothing but potato chips, it is going to take a really large amount of chips, along with a REALLY large number of calories to fulfil your nutrient requirements.

An animal nutritionist told me that different animals have different core nutrients that drive hunger and satiety. For example, grazing herbivores often need to eat a certain amount of fibre before they feel full and stop eating, while primates need to eat a certain amount of protein before they feel full. For either group, if they don't get enough of that nutrient, they will likely continue eating and be at risk of obesity. This is probably a gross oversimplification. But you mentioned that you were eating more protein at the start of the day, and have possibly replaced a few high-energy, low-nutrient foods, with a variety of low energy, high nutrient foods. Which may be part of the reason that your hunger (or desire for nutrients) is reduced for the rest of the day.

2) The second theory revolves around the resident gut bacteria (the “gut microbiota” or “gut microbiome”), possibly the most underrated organ of the human body, consisting of bacteria, protozoa, and even worms. The importance of the gut microbiome is more obvious in some species than others. Specialist herbivore species (eg. horses, rabbits, guinea pigs, ruminants, koalas, kangaroos) may very well die from severe disruption of the gut microbiome (dysbiosis) through the use of certain oral antibiotics. The role of the microbiome becomes less obvious in omnivores and carnivores, although, I believe is still important. Recently, I personally experienced severe illness and inability to digest any food other than dairy products after a course of antibiotics, which was a dreadful experience.

The types and proportions of organisms that make up an individual’s gut microbiome can be dependent on what species you are, but also by diet (more so in some species that others). For example, the gut bacteria in a baby mammal drinking milk can be vastly different to the bacteria in an adult of the same species, who consumes mainly solid food. By feeding the bacterial population a certain type of food over a long period, certain species of bacteria that thrive on that food are likely to do better that other species that prefer a different type of food substrate. Suddenly changing the diet from Food A to Food B, is potentially going to 1) upset the population of bacteria currently in the gut that has adapted to thriving on Food A, and 2) result in less efficient digestion and uptake of energy since the current bacteria may not be very good at processing Food B. An example of this is that dogs and cats that are suddenly switched from one brand of food to another brand (because the bag of food ran out) frequently develop diarrhoea and gut discomfort, whereas pets that are slowly transitioned over a number of weeks do a lot better. Also, trying to eat red meat after many years of not eating it at all is a really unpleasant experience.

This could potentially explain how many people who diet for weight loss for the first time report experiencing great success initially, regardless of what the new chosen diet actually is (eg. Atkins, paleo, salads, smoothies, potatoes…), but later seem to “plateau” and even gain the weight back after a while, despite sticking to the diet and exercise plan.

A good scientist would collect a faecal sample before, during and after dieting, for analysis.

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Plant Sciences, Zoology & Evolution / Re: Do animals know they will die?

« on: 27/05/2017 08:43:29 »

Why wouldn't they be aware of those things? The would still experience illness, hunger and shortage of resources (food, water, shelter, nesting materials). They would still potentially see deaths that occur around them, and experience the loss of family members/mates. They wouldn't have previously experienced death for themselves, but then, what living animal has?

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Marine Science / Re: Are marine species immune to the bone-eroding effects of microgravity?

« on: 20/05/2017 14:35:30 »

My understanding of physics is pretty basic but I agree with what Colin2B has said. There should still be gravity acting on animals in water. The difference between water and land is that there is an additional effect of gravity acting downward on the animal (weight of water above the animal) and a buoyancy force that is acting upwards (or downwards).

I am finding it a little difficult to imagine that a large water column with an oxygenated atmosphere could exist in a zero-gravity environment. Wouldn't the water all just randomly float away, leaving behind a dry whale? Or are we talking about a giant bowl containing water, oxygen and a whale? Either way, I don't think this animal is going to live long enough to experience bone density issues.

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Plant Sciences, Zoology & Evolution / Re: Why do birds stand on one leg when they rest and sleep?

« on: 17/05/2017 12:11:13 »

I wonder if it's also related to some birds being able to sleep half of the brain at a time. Perhaps, if one leg is going to undergo sleep paralysis and cause you to potentially fall over as soon as you nod off, it is better to tuck the leg away in a balanced position, before you attempt to sleep.

Other thoughts: Possibly to temporarily allow increased circulation in the rested leg. We know that some birds that bear abnormally large amounts of body mass on one or both legs (eg. due to being overweight, frequently standing on unusually hard ground, or having an injury of the opposite leg) can be at increased risk of inflammatory disease of the feet (i.e. pododermatitis). A domestic chicken that loses one leg, for example, is highly likely to develop pododermatitis in the foot of the remaining leg due to its large body weight (and probably a severe change in the way it has to get around). Relieving one leg from bearing weight may allow blood to flow to the extremities of the foot with less effect of gravity and pressure, although it does imply that the other leg would have to bear more weight while this happens.

Lastly, maybe it's just a security mechanism, like an alarm, to wake the bird up to any disturbance that causes it to become unbalanced.

Lots of possible reasons, but I don't think we know the definitive answer yet.

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Physiology & Medicine / Re: Why do right handers stir their tea in a clockwise direction?

« on: 13/05/2017 03:50:43 »

Interesting. I have a different perception. In stirring outwards I need to move the whole wrist, which makes it much more unpleasant for me as it feels a bit clumsy and I need more engery for this. If I stirr inwards, I can accomplish the stirring by basically just moving my thumb and forefinger, which is a rather small movement.

I have, btw, this weird habit, that I need a spoon in my tea, even though I drink it without milk or sugar. Maybe the ruminant movement is one reason for this ;-)

Your first point demonstrates the difference between the precise, fine stirring technique of a German, versus the grotesque wrist gyration of an Australian...

The second thing is indeed quite weird. Do you enjoy the spoon stabbing you in the eye?

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Plant Sciences, Zoology & Evolution / Re: Do animals have weird dreams?

« on: 08/05/2017 12:01:38 »

It's quite difficult to establish exactly what an (awake) animal is thinking, and to validate our assumptions (using existing technology), given that most animals do not speak human. We can sort of make some broad assumptions about what an awake animal might be thinking based on the environmental situation and body/facial language patterns, but who's to know if we are completely wrong? It would be even harder to communicate with a sleeping animal, since there is largely an absence of body language during sleep. And they will never tell you what they dreamed about afterwards, in order for you to validate your theory.

Some dogs appear to run during their sleep. Whether they are dreaming about running through the fields, or if it's simply a spontaneous outburst of memorised muscle movement: hard to say. While it's easy to jump to the conclusion (with a little anthropomorphism) that a cat that licks its lips during sleep might be dreaming about food , I've never seen a cat chatter during sleep, as they often do while hunting birds, or hiss and swipe as they often do in a fight. So, if cats do indeed dream about these topics, it doesn't seem as though those dreams consistently translate into observable muscle movements.

What constitutes a "weird dream" anyway? In my (human) experience, a 'weird' dream is usually one in which the events or behaviours of the characters deviated from what is expected or socially acceptable. My opinion is that animals don't tend to have as many rules and expectations as humans have constructed for themselves. So, while we might think that waking up very late, walking around naked in public, eating some random old faeces, licking one's own anus, and then mating with a sibling would be a pretty crazy dream...perhaps not so weird if that any/all of that occurred in an animal's dream.

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Plant Sciences, Zoology & Evolution / Re: Why do elephants have grey skin?

« on: 02/05/2017 03:38:30 »

Colour (as in skin pigmentation) could be energetically expensive to produce and maintain. Some animals use colour for camouflage or to confuse predators; others use it to attract a mate. But if you're one of the largest animals on land, have no need for camouflage, live in a herd, and competition for females exists in the form of big, strong males fighting, it is probably not worthwhile producing massive amounts of skin pigmentation. More useful to have skin that is resistant against UV exposure and helps maintain an ideal body temperature.

I am always puzzled why 'aliens' in films look so humanoid. Lack of imagination? Or do we really think that a life form that evolved in a distant planet/galaxy under completely different conditions would just so happen to look just like us, but with bigger eyes and forehead?

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Technology / Re: Why aren't elevator buttons set out as you would read them?

« on: 27/04/2017 05:40:05 »

... with the button for the nearest floor being the hardest to reach...

It's evil and wonderful.

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Plant Sciences, Zoology & Evolution / Re: Is it true puppies get the best out of both parent's genes?

« on: 24/04/2017 13:27:13 »

Breeders of "designer breed" dogs tend to advertise their puppies as all having the most desirable traits of each breed. A common example is when the breeder of Labrador X poodle (commonly referred to as the "labradoodle") will claim that the dog is highly intelligent (implying a poodle trait), non-shedding (poodle trait), easy to train (Labrador trait), friendly (presumably a Labrador trait), and hypoallergenic (made-up trait).

Strangely enough, they never seem to entertain the idea that the puppies could be a boisterous (Labrador), allergic to everything (poodle), hypochondriac (poodle), indiscriminate eater of garbage (Labrador) with horribly hairy ears (poodles) and chronic ear infections (both breeds). Genetic wishful thinking...

The actual puppies could be some random combination of the genes of each parent, and may even be different from the other litter mates. Just like puppies in the same litter can be different-coloured and different-sexed, they can also be of different disease status. If it's lucky, the pup might not get a certain defect that its parents had. If it's unlucky, it may end up with two deleterious genes and be clinically diseased compared to its parents (if each parent only carries one deleterious gene for a particular trait).

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Plant Sciences, Zoology & Evolution / Re: Do pigs return to their own hut?

« on: 18/04/2017 04:24:17 »

They probably tend to return to the same hut, as creatures of habit. However, (without knowing the specifics of the farming practices in the the country that Margaret is in), it is likely that the free-range pigs are rotated onto different pastures periodically. This is because pigs can graze an area of pasture heavily and deposit a very high level of nitrogenous (nitrogen-based) waste onto the ground, which makes it very difficult for the grass to recover and grow back while the pig continues to live there.

Here in Australia, free-range pig farms are usually sub-divided into small plots, like a rough grid, with some plots containing pigs and others left to allow the pasture to recover (which can take months to years). I've seen some aerial photographs of these farms, which spectacularly show lovely, green, unused plots, contrasted against the bare dirt of the ones that have housed pigs. So, within the pig's lifetime, it will probably live on several different plots of land. Presumably, the farmers also move the hut(s) to the new plot, unless it's easier/cheaper to construct a new one.

As for territorial, wild pigs are quite territorial. Domestic pigs seem to (mostly) get along or at least tolerate each other. They can do some pretty serious damage to each other when they decide to. They might get along with some individuals more than they do others.

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General Science / Re: Should we ban pit bulls?

« on: 16/04/2017 09:13:02 »

Today's 'pit bull' dog is no particular breed. It can be any mix of a number of stocky, bull-type breeds which include the Staffordshire bull terrier and its American descendants, which gives the dog an overall stocky appearance and head shape. There is no set genetic definition for what makes up a 'pit bull'. While there are commercially-available DNA test to determine what breed(s) your dog is, the results cannot stand up in court because there are no specific markers or genes that make a dog a certain breed. For example, it is not uncommon that a result that a small dog that looks like a poodle mix breed will indicate a completely different breed (eg. a rottweiler) as a descendant. So, at least for now, those test are mostly for fun, if someone has a little extra cash they want to spend.

Sometimes, experienced vets get called into court to give an opinion on whether or not a certain dog LOOKS like a pit bull. But even with experience, you can't really tell for sure who the parents of a mixed-breed dog were. It's an educated guess. A lot of stocky, big headed dogs could conceivably be a Labrador retriever mix, or something completely different. All you have are the physical features of the dog in front of you. That could be due to pedigree from similar parents, or it could be due to the chance expression of different genes from completely different looking parents. I once got very excited about seeing a patient who was the offspring of a dachshund and dalmatian...it turns out it looked exactly like a normal dachshund. Physical appearance is just not a reliably indicator of breed.

So, I think that the difficulty in determining the exact breed of a dog makes banning them nearly impossible, legally, unless you are also happy to destroy a whole lot of dogs that were never of any bull-type descent.

As for whether they are dangerous: physically, that build of dog makes it potentially dangerous if they decide to attack. But behaviourally, the unsocialised, untrained ones are no worse than your unsocialised, untrained chihuahua, Jack Russell terrier or Labrador. In fact, Labradors are rated as one of the most likely breeds to bite you, and little dogs are often ill-tempered and bitey - they just don't have the 'machinery' to kill you.

The media has a tendency to call every dog involved in a dog attack a 'pit bull' (when it is clearly a completely type of dog), so it's likely that the number of pit bull attacks you see in the news is greatly over-represented by this over-simplification. Just like how every shark is "5.5m long"... (how they can accurately measure the length of a shark, moving, in water, in the wave zone, from hundreds of metres away is beyond me).

Some 'pit bulls' are nice, some are not nice; just like any other breed. I think it's dangerous to imply that a breed is 100% safe, as much as it is silly to imply that it is 100% dangerous. The truth is somewhere in between and is different for every individual dog, different for every individual situation that the dog is in.

A few too many people seem to think that their dog is 100% safe when no animal is such. When people do silly things like placing their newborn baby on their dog's face...or leave their child of a poking, tail-pulling, ear-grabbing, face-hugging age, alone with their dog, disaster is not far away. Sometimes the parents are unaware of the dog's body language when the dog is communicating its discomfort, and children cannot be expected to understand dog body language and boundaries when unsupervised.

So going back to breed question, when the dog that is pushed beyond its tolerance threshold is a chihuahua, the child gets a few bites that heal into scars. When the dog is a pit bull -type, then much more damage is possible. So that's why you tend to hear about pit bull attack, rather than chihuahua attacks.

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Plant Sciences, Zoology & Evolution / Re: Are birds born knowing the songs they sing?

« on: 15/04/2017 13:16:48 »

It's difficult for a bird to change the 'tone' of its voice because that is mostly due to anatomy. Birds have an air-filled 'syrinx' located where the trachea branches into two bronchi, which is responsible for the unique voice that each species has. But there is definitely also a learnt component to rhythm and control of the sound in a bird's song.

If anyone has table manners that are as appalling as mine, the next time you cook up poultry, complete with a neck, you should dissect out the trachea, locate the syrinx, cut it out, and then blow on it. This works particularly well for ducks, which are known for their amazing syrinxes. You'll sound exactly like the duck (...used to).

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Plant Sciences, Zoology & Evolution / Re: How is frogspawn fertilised?

« on: 15/04/2017 12:54:04 »

This is a fairly complex question to answer because there are many, many species of frogs and for almost anything you try to say about them, there is always a species that will break the rules. But generally, frog eggs are fertilised externally (outside the body). This is different again to other groups of amphibians. The female frog lays a cluster of eggs into water or a damp substrate, and the male deposits his sperm on top of the eggs. Microcopically, the surface of each egg cell has a specific 'zone' at which a single sperm can enter, and other areas where it is impenetrable. When a healthy, 'fit' sperm contacts the egg, it fuses with the egg's membrane. Some rather complex molecular and chemical signals start to happen at this point, which I won't get into (mainly because I don't fully understand them myself). Eventually the nucleus, containing the all important DNA of the male frog, is able to move into the egg where it can combine with the female's DNA, already in the egg and begin the process of forming an embryo.

Overall, the process is not too dissimilar from what happens internally in other species, including mammals, or externally in fish. Arguably, land animals that use internal fertilisation are the weird ones...

Most of the current knowledge is based on a few 'model species' (the ones scientists often like to study in the lab). But the more we learn about frogs, the more differences we are bound to find...and the less we are able to make a single, generalising statement about "what frogs do" because there are probably thousands of versions of frog reproduction out there.

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Plant Sciences, Zoology & Evolution / Re: How do birds reproduce?

« on: 14/04/2017 10:47:11 »

Hi Sarah,

Birds actually undergo internal fertilisation, like mammals, even though they lay eggs externally. The egg is fertilised well before it has a shell, or a 'white' or even the majority of the 'yolk'. The male's (sometimes males') sperm cells travel from the female's cloaca (the single main opening for urine, faeces and reproduction) towards the top of her oviduct, where mature eggs are deposited from the ovary (ovulation). There in the upper oviduct, sperm can either fertilise an ovum immediately or be stored in special tubes for later. Sterm storage occurs so that the female doesn't need to mate multiple times to fertilise a whole clutch (since ova are not all released at the same time), and also because it allows some flexibility in the exact timing of the mating event (she doesn't have to find the right mate at exactly the right time to match for her ovulation).

Each fertilised eggs then continues to develop and travel down the oviduct and uterus, gaining its yolk, white (albumen) and finally shell over about 20 hours, before finally being laid as a shelled egg. Apart from fertilisation itself, the egg's development is not all that dissimilar to making an unfertilised egg, which is why the unfertilised chicken eggs you eat are almost exactly the same as the fertilised ones at the farm.

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General Science / Re: How can science be correct if theories are always changing?

« on: 28/10/2016 14:53:49 »

The beauty of science is its intrinsic ability to continuously question ideas and to allow several plausible ideas to exist at the same time. Good scientists are open to challenging and reassessing their previous ideas, and are open to accepting new ideas, should the evidence (demonstrated through sound, repeatable study methodologies) demonstrate those new ideas to be more 'correct' than the previous. And those new ideas, in turn, can be challenged again in light of additional information.

We are never really 'correct' but we should continuously seek evidence to minimise the degree to which we are 'wrong'. Nothing in science is ever 'proven'.

This is different to choosing one idea, declaring it 'correct', and continuing to accept it as 'correct' for the rest of eternity.

However, the general public sees this as: "Scientists keep changing their minds. Scientists are not sure if they are correct. They must not know anything." (Which, in my opinion, is a failure of effective science communication in the general news media. But that's a whole other story...)

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General Science / Re: How close are we to building a human memory-erasing machine?

« on: 23/04/2016 13:19:24 »

I'm sorry, what was the question again?



Can't help myself.

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Physiology & Medicine / Re: Why are dogs prescribed carprofen?

« on: 22/04/2016 14:43:56 »

Common, over-the-counter, analgesic medications for humans are frequently toxic to other animals, including dogs and cats.

The most common preparations for humans, at least in Australia, are ibuprofen, paracetamol (acetaminophen) and aspirin. Ibuprofen causes severe gastric ulceration, acute renal failure and sometimes neurological disease in dogs. In cats, it causes acute renal failure and gastric ulceration. Paracetamol causes hepatic failure in dogs, and a form of haemolytic anaemia in cats. Aspirin does it all: liver toxicity, acute kidney failure, gastrointestinal ulceration, haemolytic anaemia, neurological dysfunction, respiratory disease.

What's worse is that human medications are made in standard human-doses, for human-sized humans. These are usually MUCH higher than what should be given to a pet (even if the drug had been of a safe type in the first place). The dose rates used in humans cannot be translated directly into animal doses. Every species has different physiology, different drug absorption, drug metabolism (eg. missing enzymes for drug breakdown), and drug excretion. Drugs that cannot be metabolised or excreted will not be removed from the body, and will continue to circulate the bloodstream, causing more damage. The cells and organs of one species can be more or less sensitive to damage by a given drug, compared to another species. Adult humans are typically somewhere between 50 and 100+kg , while most pets are many times lighter than that.

Some medications are also formulated with additives such as the sweetener xylitol, which again is liver toxic in dogs.

It is unfortunately an all too frequent occurrence in both veterinary general practice and emergency medicine that pets present with life-threatening toxicities due to being given these drugs by their (often well-meaning) owners. Ironically, the toxicity is usually far worse than the condition the owner was trying to self-treat in the first place. It always sucks to die just because you had a sore toe.

Carprofen is a licensed drug for dogs in many countries, and is both widely-available and inexpensive. Being registered for administration in particular species, for a particular purpose, at a particular dose range, at a particular frequency, and by a particular route, means that that drug has been thoroughly tested in pre-clinical and clinical settings, and has been shown to be safe for use under those conditions.

A clinical exam is a good opportunity for a veterinarian to assess an animal for underlying disease, such as pre-existing liver and kidney dysfunction, so that an appropriate medication can be selected for that animal; and so that certain drugs can be avoided if there is a heightened risk for that animal's condition. The visit also allows the animal's body weight to be measured, so that the precise dose required can be calculated and prescribed. Obviously, it also allows the veterinarian assess for the actual cause of the pain and address that.

It is never a good idea to medicate an animal at home without consulting with veterinarian. Please don't.

That was the short version.