Why Kidneys Fail
Nephrons are microscopic funnel-shaped tubes that perform filtering and reabsorbing operations. Poisons, aging, infection, trauma, cancer, autoimmune diseases, and genetic predisposition can damage them. When this happens, nephron activity ceases. The kidneys will continue to operate, but they will have lost their ability to concentrate the urine. When damage occurs gradually, the remaining nephrons can grow larger and the body will attempt to compensate by stimulating thirst and altering blood pressure; if more water passes through the kidneys, toxins can still be removed despite lower nephron efficiency. Ultimately, the animal cannot drink enough and toxins begin to build up. This is called uremia. Due to the body's ability to compensate, many dogs won't begin to show obvious signs of kidney insufficiency until after approximately 75 percent of the kidney function has been lost. At this point, toxins will start to build up and the symptoms of kidney failure will become evident.
Results of Kidney Failure
If the kidneys fail to perform, they cannot clear the blood of the toxic waste products, including urea and creatinine. Urea is a nitrogen-containing byproduct of protein metabolism. Creatinine is a chemical byproduct of muscle contractions and metabolism.
As kidney function is lost, toxins will build up in the bloodstream. This is called azotemia. Blood tests can measure the amount of blood urea nitrogen and creatinine to determine the degree of kidney damage. Different animals can tolerate different degrees of azotemia, so not all azotemic animals will seem sick. However, as these values increase, dogs will feel sicker and will show signs of uremia or poisoning from these increased levels of toxins.
Loss of kidney function will also create imbalances in the calcium/phosphorus ratio and losses of potassium and blood proteins in the urine.
Kidneys in Balance
The key to avoiding kidney disease is prevention. When kidneys fail to function, all the organs in the body are affected. The holistic approach views the body as a whole, rather than concentrating on only one organ, whether diseased or healthy. Therefore, it's important to strengthen and balance all organs in the body. This takes pressure off the weakened kidneys and allows them to work at their optimum level.
Water Is Important
Your dog should always have access to fresh water. Giving your dog plenty of grated fresh or lightly steamed vegetables, which contain high water content, is another healthy addition to his diet.
Does the type of water a dog drinks really matter?
Yes. Filtered water is recommended, although steam-distilled water or reverse osmosis is better for dogs with lower urinary tract disease, as it moves inorganic minerals. Always add plenty of fresh water to your dog's food, and adding some organic apple cider vinegar to the water dish helps clear up any yeast infections and prevent any future ones from forming.
Getting Rid of Toxins
In dogs with normal kidney function, food with lower protein levels results in fewer byproducts being created. For dogs with kidney problems, these byproducts are not eliminated easily. And, the fewer number of toxins ingested, the easier the excretion process. So, to prevent protein malnutrition, the best diet for a dog with compromised kidneys is a food with reduced but high quality and highly digestible protein.
Causes of Kidney Failure
A wide variety of diseases and conditions contribute to kidney disease. This section outlines some of the most common.
Bacterial Kidney Disease
Bacteria can cause kidney infections. The bacteria can ascend to the kidneys from the bladder or can descend to the kidneys through the bloodstream or from other organs.
Leptospirosis is a contagious bacterial disease that affects dogs and humans. It impairs kidney function and may result in kidney failure. It is spread by infection by a bacterial pathogen called leptospira. Signs of leptospirosis include vomiting, impaired vision, and convulsions. The disease is transmitted by contact with the urine of infected animals or objects contaminated with the urine of infected animals.
Although a vaccination for leptospirosis is available, some dogs experience allergic reactions to this vaccine. While the risks of not vaccinating for leptospirosis were once thought to outweigh the risks of vaccine reaction, the type of leptospirosis that is protected against in the vaccine is often not the type that dogs come in contact with, frequently rendering the vaccine ineffective. For this reason, many veterinarians do not use this vaccine unless the risk for infection is substantial.
Antifreeze and Rat Poisoning Danger
Ingesting even a small amount of ethylene glycol–based antifreeze that may have accidentally spilled on your driveway can impair your dog's kidney function.
Antifreeze has a sweet taste that attracts dogs, but it is deadly. About 10,000 pets every year die from antifreeze poisoning. It immediately forms crystals inside the dog's nephrons. A better alternative to protect your car and dog is to use propylene glycol–based antifreeze. Decorative snow globes can also be dangerous if broken; about 2 percent of a snow globe is antifreeze.
Rat poison containing calciferol (a form of vitamin D) is also lethal to dogs. When it is ingested, the calciferol increases the dog's calcium level, which causes mineral deposits, inflammation, and additional damage inside the kidneys.
While most antibiotics will not harm the kidneys, a few can damage the nephrons. One of these is gentamicin, which inhibits bacteria by suppressing protein synthesis and growth. The anticancer drug cisplatin and amphotericin B, a drug for serious fungal infections, can also cause acute kidney damage.
If a conventional antibiotic is prescribed for your dog, always ask your veterinarian about the benefits and risks and discuss other options.