I find the information on dogs & "hop toxicity" interesting - as I am a veterinary anesthesiologist, avid home brewer, and the owner of 3 dogs, including one greyhound. Here are my observations:
I don't think what has been described as 'hop toxicity' has anything to do with malignant hyperthermia, which is a genetic disease triggered by certain chemical compounds, and is fatal w/o rapid intervention with specific drugs (dantrolene). There are other hyperthermic reactions that have been reported in some specific breeds of dogs (including greyhounds) that share some similarities to MH, but are usually not fatal.
That being said, the medical evidence in the literature for 'hop toxicity' is very limited - little is truly known. Also, in my experience to date, brewing in a shop with lots of dogs milling about (our own, our neighbors, and other friends) one thing I've noted is that MOST dogs show absolutely no interest in hops. Potentially toxic? Maybe. Likelihood of toxicity? Pretty low. Do we allow our dogs free access to spent hops? No. Are we paranoid about our dogs having access to hops? No. If you see that your dog has a tendency to ingest hops, I would be careful, but most dogs, in my experience, just are not interested...
Ron Mandsager, DVM, Diplomate, American College of Veterinary Anesthesiologists
Associate Professor, Veterinary Anesthesiology
Oregon State University