Kidney disease can occur any time, and there is evidence that hypertensive dogs have a predisposition to it. The anapril or Enalapril is also commonly used to modulate progression of kidney disease. Presumably your dog has been on this medication for a long period of time? There are some warnings in the literature than a larger than needed dose may have a deleterious effect on the kidneys. So this drug is a double edge sword of sorts. If titrated correctly not only does it have a benefit for the heart, but also in slowing down several forms of kidney disease.

Kidney disease frequently increases gastric irritation by increasing acid secretion. In essense your puppy may be feeling the equivalent of heartburn and nausea at the same time. What you need to ask your Vet is for the appropriate dosage of randitine (Zantac) to give your dog. As an example for a 60-70 lb dog 75-150mg once or twice a day is the dosage. What it would be for a 4 lb dog only a Vet could calculate out. Zantac usually takes up to 2-4 hrs to really start to work and block the acid. If the dog refuses to take the Zantac pill it is available as an IV solution. Also Sucralfate which coats the stomach lining has another beneficial property of being able to bind phosphate which can help kidney function.

As an additional step I would strongly urge you to have the Vet give the dog an IV of Zofran. It is extremely effective in supressing nausea, and of course extremely expensive. Also inquire about getting the appropriate 7 day supply of metoclopromide for days 2-7. The metoclopromide is a less effective 1st generation medication for nausea, and also much cheaper and more widely used in Veterinary medicine. High doses may affect the heart. No known effect of Zofran on the heart.

Once you have the acid blocked with the Zantac, and the nausea relieved with the Zofran, you just might be surprised how hungry your dog becomes for the Hills k/d. But until you get the gastric irritation and nausea under control it's very unlikely your dog will want to eat anything.

The idea of the Hill's K/D is that the protein source although low has been hydrolyzed into simple peptides. This is something the damaged or failing kidney can cope with. If you try to wing it with some home recipie it could be disasterous for your dog.

Currently your Vet has probably been working on getting phosphate levels down in the blood via phosphate binders. Yet another reason for the Hills K/D as it has low phosphate and low salt content. Once you get the kidney function stabilized, and the dog eating, then supplement the diet with fish oil as the Omega-3 fatty acids besides being good for the heart, also helps slow down kidney disease. But use the fish oil and NOT fax seed oil.

Good luck to your puppy.