This is something I've been researching for quite awhile now. If lack of sunshine is causing Vitamin D deficiency, therefore causing cancer, death, and a multitude of other health problems in humans, I think it is safe to say that it might be affecting our dogs, as well.
Think about it... our society spends so much more time indoors than we did in the past. We spend hours upon hours on the internet, emailing, chatting, etc... And every day we hop in our vehicles to go to work where many of us are inside offices all day, drive back and forth from home, getting minimal sunshine.
Dogs are more a part of the family than ever, too. You don't see as many dogs living outside, many of us have strictly indoor pets. When the weather is less than optimal, too hot or too cold, these pets go outside to potty and exercise maybe 10 minutes at a time, several times a day. Then they spend the rest of the day lounging indoors.
In the summer we worry about heat stroke with our mastiffs, so we cover them up when they are in the sun, shuttle them from air conditioned house to air conditioned vehicles.
In the winter they are hardly outside at all, and neither are we!
When people breed mastiff litters, they want to socialize them as house dogs, and shelter them from potential disease, keeping them indoors for most of their first 8 weeks.
What about winter litters who are kept inside for almost 100 percent of the time? I bet if you did a study you would find many many more growth related issues in puppies raised strictly indoors and/or during the winter.
Vitamin D plays an important role in the maintenance of organ systems.
Think about it.. we are breeding the largest, heaviest bone breed of dog in the world. Bone development and mineralization are of utmost importance. If, for whatever reason, the asorbtion of important bone forming minerals is inhibited during any of the growth stages, what strain will this cause on the other systems?
More than any other breed, I think a lack of vitamin D in mastiffs would manifest in problems, simply because of the rapid growth they go through, it is critical for all the minerals and nutrients to be properly absorbed.
I had a pet brindle boy who had growth issues with his front legs, bowed front legs, starting at 5 weeks... NO vet could figure out what was going on. Many of them recommended crate rest. (indoors) I got him at 4.5 months old.
We had his front legs x-rayed around 8 months of age... what did they find? Enlarged ends of bones, multiple cross-struts across the medullary cavity... classic signs of rickets. AKA vitamin D deficiency. He did have marked improvement after Ester C, Cod liver oil supplements (Vit D), switch to Eagle Pack Giant Puppy food, and daily mild exercise outdoors.... but passed away at 1.5 years to lymphoma. Unrelated? I don't think so.... go back up to the last two bullets about what Vitamin D does......
Wikipedia: Vitamin D regulates the expression of genes associated with cancers and autoimmune disease.
By the way, he had an enormous, square head, the biggest I've seen on a mastiff between 1 and 2 years old......
Also from Wikipedia: Rickets symptoms: Changes in the skull also occur causing a distinctive "square headed" appearance.
My own personal research has led me to believe that lack of Vitamin D caused the problems in him, whether it be lack of sunlight, and/or other reasons for improper absorbtion. And I am beginning to think that lack of Vitamin D may be causing different problems in a lot of mastiffs.
Wikipedia: D deficiency is known to cause Osteomalacia, a bone-thinning disorder that occurs in adults and is characterized by proximal muscle weakness and bone fragility.
Osteoporosis, a condition characterized by reduced bone mineral density and increase bone fragility.
In dogs, couldn't those conditions present as hip and/or elbow dysplasia?
Heart Disease and Vitamin D
Research indicates that vitamin D may play a role in preventing or reversing coronary disease. Vitamin D deficiency is associated with an increase in high blood pressure and cardiovascular risk. When researchers monitored the vitamin D levels, blood pressure and other cardiovascular risk factors of 1739 people, of an average age of 59 years for 5 years, they found that those people with low levels of vitamin D had a 62% higher risk of a cardiovascular event than those with normal vitamin D levels.
As with cancer incidence, a qualitative inverse correlations was found between coronary disease incidence and serum vitamin D levels of 32.0 versus 35.5 ng/mL. Cholesterol levels were found to be reduced in gardeners in the UK during the summer months.Heart attacks peak in winter and decline in summer in temperate but not tropical latitudes.
I think it's very interesting that cholesterol levels and heart attacks were reduced in the UK during the summer months. Could it be because Vitamin D acts as a "transporter" and enables the fatty acids to be easier absorbed in the intestine, and transported to the right places in the body. When you don't have Vitamin D as the "transporter", the fatty acids, minerals, etc, aren't properly absorbed.. (and end up clogging the arteries?)
Speaking of absorbtion , we already know what happens when calcium and phospherous aren't properly absorbed, what about other things? How about amino acids? Let's look at cystine, for example.
In newfoundlands, there is a genetic defect that affects the absorbtion of cystine in the kidneys. Since the cystine can't be absorbed, it is excreted in the urine, sometimes causing stones and blockage.
It is a recessive disorder and the gene has already been found in Newfs.
Mastiffs are being diagnosed, as well. But in mastiffs, they just can't figure out the inheritance... they don't have that same defective mutation gene as the Newfs do for improper kidney absorbtion.
Furthermore, many mastiffs diagnosed don't ever have symptoms, and some test negative many times before testing positive, making it complicated.
Here's a big "what if"... what if, in some mastiffs, the improper absorbtion is occurring in the intestine, and NOT the kidney? Especially in dogs who never develop symptoms, could a lack of Vit D cause some of the Cystine amino acids to not be absorbed in the gut, slip by, and go into the urine - producing postive readings?
Why the heck are they asking for color now when you submit samples for cystinuria? Do they think there is a gene linked to color? Are more brindles diagnosed than fawns? Does anyone know the percentages? I definitely hear of more brindles than fawns......
Keep in mind that brindles have darker pigment than fawns. Also keep in mind that the current Vitamin D deficiency crisis in the USA is affecting more african americans than any other race. Reason - darker skin takes much longer to absorb enough Vit D from sunlight.
Is there a connection? I honestly don't know, but maybe it's worth looking into.
In conclusion, I think we, as mastiff fanciers, should give consideration to the effects of Vitamin D deficiency on our dogs, as well as ourselves. I would love to see some studies done on various diseases compared to Vitamin D intake and levels of sunlight exposure.
If anything, lets get off the computers for an extra 15 minutes a day and go sit out in the sun with our mastiffs.