I would agree with that, Cooper also had heavy shedding  along with the limp, he also had always had fairly heavy shedding spring and fall being part Newfie, but when the bone cancer came he shed with a vengeance. After his amputation he actually came to the point where he shed very little at all and developed a beautiful shiny coat. Before he developed the cough he began to shed again, and in my heart I felt it was because the cancer was returning, so yes , if it helps anyone in diagnosis , I will say I think it was definitely a telltale sign. And this wasnt just long hair type shedding it was HEAVY shedding where you could remove handfuls of hair that just slid out of his skin. 

Coopsdad

I don't understand, and to be honest, you guys are scaring me a little.  What does shedding have to do with cancer?  My mastiff is shedding like he never has before, he has been blowing his coat for about 3 months now.  I noticed about 3 weeks ago how much different this year is with his shedding than all of the past years.

What does this have to do with cancer?  Please explain

Dogs shed with different intensity for many, many reasons. Historically, the number of hours they are exposed to daylight regulated this process, with peak shedding occurring in the spring and fall. Since most pet dogs live inside, this cycle is generally interrupted and many dogs shed year round. Stress of any kind…..from an external or internal source, can cause excessive shedding. Diet is also a large influence. Thyroid issues as well as cancer have long been related to increased shedding and anecdotal references are easily found. It is also very likely that there may be no clinical signs of illness when a dog is shedding from an unknown internal stressor.

Trying to isolate one factor for any dog's increased shedding in varying environments and our ever changing climate, is a nearly impossible task. A valid, controlled study woud be virtually impossible and likely of very little clinical significance.

Our poodle neighbor even shed this year. My dog (and her young healthy lab friend) shed very little, primarily because they eat a raw diet, yet both are did so excessively this year, yet their coats are luxurious. It did not happen at the time either of her cancers were diagnosed, but both were found quite early, she has always had abundant immune system support and was in otherwise good health and lives a relatively stress free life.

It makes sense that Cooper was displaying rapid hair loss, and Ken's observation was an important distinction….loosing clumps of hair is not shedding, but Cooper was extremely ill. Humans often experience similar hair loss under stress or illness.

It is certainly prudent to investigate anything you feel is not normal for your dog, but also wise to step back, not panic and realize this has been a year of EXTREME climate change. I don't know any dog who followed their usual pattern.

I hope I didn't scare anyone with my comments. That wasn't my intention. I should clarify, the shedding Sparky experienced could be described as clumps. Huge amounts of shedding, far beyond his normal temporary seasonal changes.  He has a top layer of fur and an underlayer,  and it was the underlayer that was falling out by the handful.  Please bear in mind he is a 30 pound beagle-mix who, somehow has ended up with a very rare cancer (histiocytic sarcoma) that is normally only seen in very large breed purebred Bernese Mountain dogs, Goldens and flat-coated retrievers.  So nothing really makes sense about this.  The vet did confirm that in some dogs, unusual shedding can be a sign of internal stress, and cancer/pain from cancer can contribute to this.

Now that you mention it, Percy was also losing his undercoat in clumps this spring, right before his diagnosis.  It seemed like no matter how much I brushed, more clumps would appear.  He had a hemangiosarcoma in his leg bone which apparently is also rare.  Another unusual thing that I noticed was, at the first appointment to check his leg, he had lost a noticeable amount of weight.  He weight has always been very consistent and all of a sudden he lost about 10% of his body weight.  The oncologist said that the weight loss was due to the tumor stealing nutrition from the rest of his body.  I had not made the connection between the shedding and his tumor before so I have not asked the oncologist about that.

Yes, a half plucked chicken is a good description :)  Little tufts of undercoat sticking out from under his outer fur.  Percy had them all over his butt and thighs.  I would pull at them and out would come giant tufts of fuzz.

I'm wondering if it was related to Percy's weight loss too.  The vet had said that Percy's weight loss right before his diagnosis was probably due to the tumor stealing the nutrition from the rest of his body.  I wonder if his hair loss might have been due to poor nutrition and weight loss which was due to the tumor.

Now that we are several months past amputation, Percy's weight seems to once again have settled in on a steady value, despite alternating days of not eating due to chemo and me letting him eat almost as much as he wants to make up for the days he does not eat.  He's always been skinny and is now underweight, which is why I'm encouraging him to eat.  I wish my weight were as steady as his!