Quote Originally Posted by kimlovescats
Jen, is it his back leg? Can you feel it to see if it feels cold compared to the others?

This is why I ask:

What is Feline Hypertrophic Cardiomyopathy?:
More easily referred to as HCM, this disease is a thickening of the heart muscle, and is believed to be largely genetic in origin, with several breeds considered suspect. It is found most often in middle-aged cats, and in males. Although there is no known cure for this condition, with prompt diagnosis and early treatment, cats may live on for years after diagnosis. HCM is often associated with Hyperthyroidism in cats. Congestive Heart Failure (CHF)sometimes results from HCM.
What are the Symptoms of HCM?:
Unfortunately, one of the first symptoms may be heart failure and death, an important reason why cats with any of the "at-risk" diseases should be monitored carefully for heart health. Other symptoms include:
Sudden appearance of dyspnea (difficulty breathing)
Anorexia
Lethargy and/or weakness
Syncope (fainting)
Limb paralysis (rear legs may be affected)
Clinical symptoms include a heart murmur or a pulse over 200. Further tests would

Jen, it's looking more like my fear! I pray it isn't!!!