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head size/shape bite strength

From what I have seen a Wolf has a bite force of a little over 400 psi and that was in a defensive bite, so pretty hard. Then I have seen a Tosa score over 800 psi. The larger head size allows for the pressure per square inch to be spread out.
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      can someone explain to me, how head size correlates with bite strength. and not just head size but also head shape? I see people saying the wolf has the strongest bite of all. Is this due to a bigger head, a different head shape? etc etc.
      what head type produces the strongest bite?
      lets elimante the factors of desire to bite, reason biting, etc. and consider all dogs are biting as hard as they possibly can.
      as I understand a dog with a wider nasal ridge, as well as larger zygomatic arch produces the most strength.
      seems to me a dog can be produced that has these features larger than a wolf.
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      • From what I have seen a Wolf has a bite force of a little over 400 psi and that was in a defensive bite, so pretty hard. Then I have seen a Tosa score over 800 psi. The larger head size allows for the pressure per square inch to be spread out.
        • Some people believe that the most powerful bite in dogs comes from those who have prognathism, that is the stronger bite is of those dogs whose lower jaw is longer than the top. That assessment is incorrect. There are two different things, namely: the length of the muzzle and the relationship between the muzzle (or maxilla) and lower jaw. Regarding the first aspect, there are basically three types depending on the long of its muzzle in relation to the skull. Brachycephalic dogs have a muzzle (measured from stop to tip of maxilla) shorter than the distance between the stop and the occipital crest. The mesoticephalics have the muzzle (measured from stop to tip of maxilla) the same length as the distance between the stop and the occipital crest, and finally the dolichocephalic with the muzzle (measured from stop to tip of maxilla higher) longer than the distance between the stop and the occipital crest, as in these pictures: Some add a fourth type the brachiocephalic extreme for those cases (like the Pug) where the dog has a muzzle extremely short: However, there are several factors involved in the production of the power of the bite and among others there is the will to bite mentioned by you. In fact many dogs bite stronger than others not because they have greater physical power, but because they do so with more will and determination. However, from the morphological point of view, which is what you have asked for, we have, in first place, the masticatory muscles (masseter) which are those that produce the force with which the jaws are closed. This implies that the larger the muscle, the greater the biting power. The larger size of the muscles requires, at a time, a larger size of the cranial-facial which is the place where the masticatory muscles are located. Thus higher bite power requires a larger size of the face/head, and that is why usually a larger dog will bite with more power. Second, is also relevant for the purpose of causing the power of the bite, the formation of the bones of the jaw over which the masticatory muscles exert their power. In other words, two dogs with an identically sized muscles, and therefore of equal power, may not have the same bite force if they have a different conformation of the muzzle. The reason is very simple and is based on the rules of physics, specifically on the principle of the lever. The jaws act as a lever of third-class which (1) attachment point is located in the condyle and temporal joint, that is where the lower jaw and the maxilla are connected. The (2) power point is precisely the area where the masticatory muscles are located, and (3) point of resistance is the border of the mandible. So it is clear that the closer is the point of power to the point of resistance, the greater the force exerted on it and therefore the greater power of the bite; and vice versa, the greater the distance between the point of power and point of resistance, the lower the force exerted on it and the weaker the bite. Consequently, the longer the dog's muzzle, the greater the distance between the point of power (masticatory muscles) and the point of resistance (border of the mandible) and the weaker the bite. The shorter the distance is between the end of the muzzle point and the point of resistance, greater the force in the bite. These figures allow us to appreciate what I mention graphically: hugo
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            While the last picture describes the relationship between the fulcrum point, the force point, and the resistance point...and emphasizes that the closer the force is to the resistance, the stronger the lever...which is true...it fails to acknowledge that a dog with a longer muzzle is able to obtain the same position by simply getting a deeper  to move the object closer to the rear of the mouth.
            There is a lot more detail about this topic on our forum...here.
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            • I would also like to mention that a short muzzle has a hard time gripping, and often times has a poorly developed point of attachment for the force (muscles) and under-developed in the pivot as well. Due to the under development of the jaws in dogs with short muzzles...I believe dogs with moderate length muzzles are actually have stronger bites than dogs with either short or long muzzles and I believe most tests would agree with my personal observations...be them "psi bite meter tests" or by feel from protection trainers.
              • from what i recently read from a post on your forum, i think that the undershot muzzle makes no sense. Simply point, if it was beneficial we would probably see it somewhere in nature, which you dont. Dogs, cats, etc. etc. none of them have the undershot bite.
                • [quote1328409745=LeeRobinson] I would also like to mention that a short muzzle has a hard time gripping, and often times has a poorly developed point of attachment for the force (muscles) and under-developed in the pivot as well. Due to the under development of the jaws in dogs with short muzzles...I believe dogs with moderate length muzzles are actually have stronger bites than dogs with either short or long muzzles and I believe most tests would agree with my personal observations...be them "psi bite meter tests" or by feel from protection trainers. [/quote1328409745] While I can agree with this to a point maybe you could elaborate where breeds such as the apbt[center][/center] While I agree with this to a point simply because it stands to common sense, maybe you could elaborate more then on where breeds such as the apbt, bulldogs and Rottweilers get their bite? While I may not have psi numbers to offer I do believe they are up there in numbers and I consider them to have relatively short muzzles compared to breeds like a Labrador retriever or German shepherd.
                  • It's like with cars. The amount of HPs may be a somewhat okay indicator of how fast a car can go, but it's just ONE factor of many really. A car can be high powered but bulky and relatively slow. Example: Hummer H2: 393HP, 105mph vs Porsche 911 Carrera: 350HP, 179mph. As you can easily imagine here, other factors DO play a role. Same goes dogs' bite strengths and muzzle lengths. Muscle mass for example is another factor, etc.
                    • good analogy
                      • And, you can't just consider the mechanics behind each vehicle. You also need to consider the mindset of the driver...as in which one is willing to give all they have.
                        • Yep! Just as a granny in a 911 may still go 35 on the interstate.
                          • you get on that horse, you gotta ride it!
                            • so basically its unfair to place it all on A without considering B and C because they all work together to give the dog the bite, which makes sense and i thought that but wasnt really sure if it was valid
                              • Localization of canine brachycephaly using an across breed mapping approach http://www.ncbi.nlm.nih.gov/pubmed/20224736 Cranial dimensions and forces of biting in the domestic dog http://www.ncbi.nlm.nih.gov/pubmed/19245503 Symphyseal fusion and jaw-adductor muscle force: an EMG study http://www.ncbi.nlm.nih.gov/pubmed/10918125
                                • What exactly is the facial reatio? Apparently the maximum bite force is a skull at 22 cm with a .51 facial ratio. Not sure if that is rated to skull width or muzzle or both.
                                  • Facial ratio Or Skull Length. Have you ever read anything on the "golden ratio"? Check out http://www.intmath.com/numbers/math-of-beauty.php ~Pretty Neat!
                                    • oh yeah, divine proportion, 1.618
                                      • In the end if bite force is a factor for a breeder the absolute best way for them to achieve that is to have some quanatative way of measuring bite force and then crunch down on it in there breeding. After they are gens deep in doing this succesfully (increasing bite force) then the animals physical form will start changing into what is most suitable for that area. In the end the best breeders are going to have ways to monitor a dogs performance in multiple areas that compute to attaining the overall goal. My family has raised and bred not only dogs but race horses for a long time and I believe dog people could take some advice from people breeding other performance animals that are bred with a much stricter/results oriented goal. Just my .02 cents
                                        • yeah, i can see how horse breeding and even training is similar as it is with dogs. my grandpa bred horses all his life
                                          • [quote1328622075=babigirl] Facial ratio Or Skull Length. Have you ever read anything on the "golden ratio"? Check out http://www.intmath.com/numbers/math-of-beauty.php ~Pretty Neat! [/quote1328622075] I see the skull length but what is the ratio to? Width or muzzle. The chart shows the highest readings around .51.
                                            • Although bite is certainly important and is one factor of many in a good program of working dogs, focusing exclusively on bite pressure alone would be far too limiting and would most likely result in a non-functional dog.
                                              • Out of the three links, I found below most helpful. Hope this helps answer your questions. "First we develop general relationships between forces of biting and variables describing size and shape. Variables include measurements of body weight (BW), skull length (SL), basicranial length (bSL), skull width (SW) and indices derived from them (e.g. ratios of facial length and skull width to skull or basicranial length). The effect of sex on these relationships is examined. Then we tease out the interactions among size and shape by subdividing each into three categories: size as small, medium and large, and shape as brachy-, mesati-, and dolicho-cephalic (i.e. short, medium, and long headed). The shape designations have long been used in breed descriptions (Miller et al. 1965) and in some morphometric analyses (Alpak et al. 2004); they parallel similar terms used in the orthodontic literature (Pepicelli et al. 2005). We recognize that the boundaries defined between categories is arbitrary for both size and shape, and that the results are likely to show some effect of the location of the boundaries. The value of the exercise, however, is in the expectation that interactions do occur between size and shape in their effect on force of biting, and that this method will demonstrate the nature of the interactions. By defining the method for locating the boundaries, it is possible for any other workers to repeat the analysis on a separate sample, and compare results."
                                                • [quote1328629268=LeeRobinson] Although bite is certainly important and is one factor of many in a good program of working dogs, focusing exclusively on bite pressure alone would be far too limiting and would most likely result in a non-functional dog. [/quote1328629268] Who said it was an exclusive focus? Maybe integrating it into a Bullygrey without losing speed and endurance in a dog that is a tight 26-28" 90-100 lbs. is the focus. [youtube]yR0OZwvBZUs[/youtube] [youtube]WO9ZBsYkXms[/youtube] [youtube]qfzUmH2Vc8A[/youtube]
                                                  • [quote1328629350=babigirl] Out of the three links, I found below most helpful. Hope this helps answer your questions. "First we develop general relationships between forces of biting and variables describing size and shape. Variables include measurements of body weight (BW), skull length (SL), basicranial length (bSL), skull width (SW) and indices derived from them (e.g. ratios of facial length and skull width to skull or basicranial length). The effect of sex on these relationships is examined. Then we tease out the interactions among size and shape by subdividing each into three categories: size as small, medium and large, and shape as brachy-, mesati-, and dolicho-cephalic (i.e. short, medium, and long headed). The shape designations have long been used in breed descriptions (Miller et al. 1965) and in some morphometric analyses (Alpak et al. 2004); they parallel similar terms used in the orthodontic literature (Pepicelli et al. 2005). We recognize that the boundaries defined between categories is arbitrary for both size and shape, and that the results are likely to show some effect of the location of the boundaries. The value of the exercise, however, is in the expectation that interactions do occur between size and shape in their effect on force of biting, and that this method will demonstrate the nature of the interactions. By defining the method for locating the boundaries, it is possible for any other workers to repeat the analysis on a separate sample, and compare results." [/quote1328629350] Yes and what is confusing me is that it states, "skull width to skull or basicranial length". I still don't know what the facial ratio of .51 is based on.
                                                    • I think these types of topics are interesting in terms of discussing things to consider...but the truth of the matter is when it comes to breeding working dogs we need to look at the total duty. In those videos...I am sure none of them test bite pressure. Instead, they test the dog's ability to work. To work, overall ability is the focus...and biting is just one of many components and is not singled out. This is my point. I recall one of your posts about some 20 different crosses that you would like to see done...and when I saw that post I thought...I hope you have 10 lifetimes and millions of dollars...and even good luck. Thinking about my program (or ANY OTHER program that has been around for over a decade and that has had specific goal/functions), over the last 12 years, I have spent well over $120,000 in my "hobby" to produce 4 generations of dogs that I like, possibly as much as $200,000. That may seem hard to believe, but if we break it down, there are 12 months a year...multiplied by 12 years, that is 144 months. If I spent just $1000 per month...that alone would be $144,000. One might think, how does one spend that much money on dogs every month. The truth is...you really don't every month, but being some month are more expensive than others I would say that is a pretty good average. My dog food bill is about $500-600 per month right now. In years past, when I had more dogs, it may have been as much as $800 per month. Then we have kennels, vet bills, training equipment, etc. It adds up. That is a lot of money to me. BTW, of course I have sold a bunch of dogs too, which offsets some of those expenses...but my point is...this stuff ain't cheap...and it is wise to spend our efforts doing things that are productive. But, why does this matter...or how does this relate to the topic one might ask...SIMPLE. We want to be EFFICIENT and PRODUCTIVE with our efforts. In order to be efficient and productive, we need to REALLY CONSIDER...how should one really breed dogs if they want to actually improve a working dog...all around. To do this, we can not isolate traits or spend time chasing every hypothetical combination. Instead, we need to bet on the most probable or strongest genetic contributions, and then practice methods that have proven to work. In doing so, we need to discuss methods of BOTH [u]culling and selection[/u]. [u]SELECTION[/u] - In terms of producing a solid working line of dogs, I think it is best not to select for any one single trait...but instead use an objective test that evaluates the dog's total quantitative ability to perform. Yes, at times we all may wish to add a dog that displays an extreme form of some trait we wish to add into our line...but when we do so...if our goal is to produce a line of dogs that perform well, we still must select for total ability and not chase that one trait exclusively. Meaning, if we want a hog dog, we do not select for bite pressure...but instead select for the ability to work a hog. (Select for the total dog). [u]CULLING[/u] - In terms of culling though, we can do BOTH select against non-performers as well as select against undesired traits. On the culling side of the equation, we can select AGAINST non-performers...and against dogs that display weak bites. Removing the bottom from a gene pool is at least as important as is maintaining the top of the gene pool...when it comes to developing or improving a breed or line of dogs. For example, take performance and hip scores. Some people think we should select for good hips, and while I understand that belief personally I think it is better to instead select FOR performance (total ability) and AGAINST bad hips (individual traits) rather than selecting for individual traits. (Select against the "non-total" dog). [u]OBJECTIVITY[/u] - Before we decide to cull or breed such a dog, we should ask ourselves...does this trait really matter? One of the best ways to do this is by evaluating the dog's performance. If the trait really matters, it should show up in performance. Now, rarely we may see dog "A" displays some undesired trait but still performs well. Should we cull this dog? Let's say dog "B" displays the desired attributes...but doesn't perform. Well...the question here is why? Some times we can't physically see why or what is going on "inside"...as is the case with "will" or "drive." Other times we may see a dog that lacks a desired "feature" but that dog kicks butt and says..."call me a non-performer if you want, but I recommend you get out of my way before I run over you...because I want some action and my actions speak louder than your words." Again, why? Does this dog have some other trait that is so beneficial it is able to overcome the "weakness?" Would this "strength" in other areas not benefit the program? Or is the breeder's identification of the "fault" inaccurate? Well...the bottom line is when it comes to "laying out guidelines" as to our direction, we much accept the fact that we are not gods, and therefore we must be willing to some degree let the proof be in the pudding. Let actions speak louder than words. Understanding this mindset reduces the chance of a breeder spinning his wheels chasing crazy ideas. I hope this made sense. Thanks for reading.
                                                      • Feel free to delete this post...as I edited my post above to address what I originally posted here.
                                                        • Most of the crosses have already been done and Molosserdogs has helped me find those rare breeds so I have gotten to see most of them. As I said before I have family in Brazil where I will be retiring and I want to bring with me the perfect dog "IMO". The first one will probably be an F1 Red Nose APBTx Working Short Haired Red and White Border Collie cross. The Aussies say the Borders are not affected by heat as much as the other breeds and everyone notes their superior intelligence. This would be my yard dog. For my house dog in A/C will by a RottweilerxAPBTxBully GreyxBoerboel.....maybe it's still up in the air. I'm looking at the SDD after seeing the size of those fangs and the Roo Dog. I want a calm dog that is explosive, endurance and hyperactivity is not a concern but it is hard to inject intelligence and not get that. Not many smart, calm dogs unless I was to throw in a Standard Poodle lol hmmm at 70lbs might not be so bad and hypoallergenic lol but I wouldn't select for their coat and really don't want retriever intelligence so the Rottweiler or SDD it is.
                                                          • Hard to get the right cross. I am happy with my girl and all the different blood she has, got lucky I guess. Since you're from Brasil, why not getting the following cross: Dogue BrazileroxFilaxBullyGrey?
                                                            • lol BoxerxBull Terrier is not one of my favorites but a Fila x Bullygrey would be interesting.
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