Enalapril: This is an ACE inhibitor. It helps to prevent constriction of the blood vessels in the heart which will help to prevent high blood pressure otherwise known as a vasodilator. It helps the heart function better and more efficiently with less work. Enalapril in rare instances can cause decreased blood flow to the kidney's.
Vetmedin: This is a newer drug with so much great feedback already. This drug is given to dogs who are in congestive heart failure and are basically considered terminal. It has helped to increase a dogs survival time significantly by 9 months. This drug acts directly on the heart by utilizing calcium to increase the contractility of the heart muscle and promote vasodilation so adequate blood flow goes from the heart to the organs of the body.
Lasix: This is a diuretic. Dogs in congestive heart failure have leaky blood vessels which causes them to retain excess fluid around the heart, lungs and abdomen. Lasix helps to pull this excess fluid out. It has also been given to dogs in late stage kidney disease as well. Yes, it can decrease the blood pressure but if there is fluid retention then the blood pressure is high since high blood pressure is usually the cause for leaky blood vessels.
All of these medications have been used in combination for at least 1-2 years with success in most patients. There is no curing CHF once it starts but it has brought more energy to dogs who otherwise would have had none and a better quality of life.
With a dog this age it would be difficult to say whether it was the medication that brought on the kidney issues, the heart disease, or the age. Stopping the enalapril could worsen his heart disease so I would just be sure to treat the kidney issues symptomatically and watch for changes in the kidney values. If the kidney values continue to rise you may have to consider stopping the enalapril at that time.
Please let me know if further assistance is needed.