• Dog owners can generally tell if their dog isn't feeling well.Dog image by Lea Petrasova from Fotolia.com
  
  Chronic kidney failure is devastating for a dog owner, who may wonder why he didn't see it coming. Washington State University's College of Veterinary Medicine explains that the kidneys are made up of tiny units called nephrons. As one nephron dies off, another begins to work until the nephron supply is depleted. Unfortunately, physical symptoms of chronic kidney failure in dogs do not appear until 75 percent of the nephrons have expired and the kidneys are barely functioning.
  
  

Increased Thirst and Urination

• Increased thirst is a sign of kidney failure.Trinkender Hund 1 image by Gerhard Fischer from Fotolia.com
  
  Perhaps the most common physical symptoms of kidney failure are increased water consumption, called polydipsia, and increased urination, called polyuria. As the nephrons die off, the dog's body cannot conserve the water the dog intakes and passes it through the urine. Washington State University (WSU) cautions that the increased urine volume may cause incontinence, and the ASPCA reports that blood is sometimes present in the urine.
  
  

Eating Disorders

• A dog refusing its treats indicates it doesn't feel well.dog biscuits image by Kathy Burns from Fotolia.com
  
  As the kidneys begin to fail, the dog's bloodstream becomes riddled with toxins and the dog begins to feel physically unwell. Unfortunately, this not only leads to depression, but in some cases the dog will lose all desire to eat. Nausea, vomiting and/or diarrhea may exacerbate these symptoms. Medications are available to help control the dog's nausea and increase its appetite, reports Dr. Debra Primovic on PetPlace.com.
  
  

Anemia

• Weakness is a symptom of anemia-related kidney failure.closeup of dog sleeping image by itay uri from Fotolia.com
  
  Another serious symptom of kidney failure is anemia. The physical signs of anemia are pale gums and weakness, according to WSU. VetInfo4Dogs.com indicates the dog may become unwilling to move, and the ASPCA says the dog may appear drunk. The kidneys produce a hormone responsible for stimulating red blood cell production called erythropoietin. As the kidneys die off, production ceases and anemia sets in. Low blood potassium is another cause of the physical symptom of weakness.
  
  

Bad Breath

• Bad breath indicates a build-up of toxins in the bloodstream.fawn pug dog image by Paul Hill from Fotolia.com
  
  Almost all dogs have unpleasant breath, hence the expression "dog breath." But if the dog's breath is unusually rancid, Doctors Foster and Smith warn on PetEducation.com that this may be a sign of kidney failure. Halitosis, as bad breath is medically termed, is caused by toxic build-up in the dog's bloodstream. In addition to halitosis, the dog may have ulcers on the inside of its cheek, tongue or gums.
  
  

Poor Coat/Skin

• An unkempt coat might indicate kidney failure.the dog image by hupper from Fotolia.com
  
  Doctors Foster and Smith list a "poor or unkempt hair coat" as a physical sign of kidney failure, and WSU indicates that the dog's skin will itch because of calcium and phosphorus deposits. These physical symptoms might be the most noticeable of all, as the dog's owner will undoubtedly see that the animal is not taking care of itself and scratching more frequently.