The Silent Killer (treatment)
This is part three of a multipart entry on the subject of Chronic Renal Failure in dogs and cats..
The primary goal in the treatment of CRF is the extension of the pet's life by stabilizing and slowing the progression of the disease. Successful treatment, though highly dependent upon the stage at which a diagnosis is made, can result in a life extension of many months to even years in the best cases.
Treatment for CRF is primarily focused upon diet and fluids. Additional treatment and medicines will be prescribed on a case by case basis to deal with other complications of CRF.
A vet will usually prescribe a specially formulated canned food for the pet that is very low in phosphorous and contains proteins that are easy to digest and produce less waste products. These formulations are also often low in sodium (in case of age related heart issues) and high in omega-3 fatty acids. Unfortunately, dogs and cats do not always find low protein wet (or dry) foods to be appetizing. Pet parents may also find the cost of special foods to be outside of their budget. Hills, Purina and Royal Canin all make prescription formulations. Royal Canin has a website just for their renal products, Purina has a page as well.
In some cases, pet owners may be able to find a suitable non-prescription low phosphorous food at their local pet store or via one of the many online retailers. As an example, Hill's Science Diet "Mature adult gourmet beef entree" is very low in phosphorous (0.5% dry matter basis) and approaches that of the prescription lines (note: there is a variation of this food without "mature" with the same low phosphorous content but about 6% points more protein). It is very hard to find a dry (and less costly), non-prescription formula that is low in phosphorous. Hill's does have Hill's Science Diet "Adult Oral Care" (0.6% dry matter basis) but it may higher in protein content (24.0% dry matter) than is suitable for a CRF patient.
As a reference, the prescription diets have phosphorus levels of 0.4 - 0.5%. Protein levels vary, with kibbles in the 10-18% range and wet as low as 3%. Keep in mind that it is not just the quantity of protein that is important but the ease with which it is digested and the amount of metabolic by products left behind. If you are unable to afford long term care using a prescription diet you must review carefully with your pet's vet the alternatives that are available to you. With some time and the correct choices, home cooking for your pet may be a good option. The pet parent must do whatever it takes to keep their pet eating enough to maintain body weight. Hme cooking may even become a requirement for finicky eaters or during later stages of CRF as appetite declines.
[A note on measurements: it can be very difficult for a pet parent to evaluate pet food nutritional content. Most bags only report "guaranteed analysis" which is a measure of minimum levels on an "as fed" basis. As different foods have wildly different moisture content "as fed" is pretty much useless. A better measure is "dry matter" basis which tries to account for differences in moisture content and is probably good for comparison of foods within a single manufacturer. The absolute best measure, however, is given in milligrams per 100 kilo calories. Unfortunately, no pet food manufacturers publish data on their packaging or websites with mg/100 kCal measurements. However, the major brands usually will be able to provide these figuresby phone or email. ]
As noted earlier, studies have shown the positive effects of a "renal" diet can be dramatic, in particular for cats. As blood phosphorus levels continue to elevate during later stages of CRF, diet alone may not be sufficient. To help lower phosphorous levels, a binder is usually prescribed. One example is flavorless aluminum carbonate in water solution given orally after eating. The binder attaches to the phosphorus so that it can be eliminated from the body through the digestive tract.
It is very important that CRF pets stay hydrated. In addition to having plenty of fresh water available, supplementation with other fluids may be necessary. Broths that are very low in sodium are one way to encourage additional hydration. In some cases, intravenous fluids may be necessary. Your pet's vet may administer these at this office on a one off basis or may recommend that the pet parent begin regular subcutaneous fluid injections. Not every pet parent will feel comfortable giving these injections (or may feel they lack the skill or a cooperative patient). However, it is usually possible to hire a local veterinary technician to come to the home periodically to administer the fluids.
Other complications that may arise include unstable sodium levels, low potassium, elevated parathyroid hormone (PTH), hypertension and anemia. Sodium levels are generally controlled with diet and are important to watch, more so for CRF pets that also have heart health issues. Sodium is important in regulating both blood pressure and volume.
Potassium is one of the most important electrolytes in the body and low levels can contribute to lethargy and reduced appetite. A sure sign of dangerously low levels of potassium is a pet that is unable to lift its head upright in a normal fashion. This symptom is more common to feline CRF patients. Potassium levels may become low as a result of increased urination and are easily supplemented. However, postassium supplementation should only be done at the direction of a vet as it may cause dangerous complications if heart disease is also present.
PTH maintains proper phosphorous and calcium levels but becomes elevated in CRF pets and Vitamin D, which works with PTH, is reduced. There are indications that elevated PTH levels may also contribute to CRF. Research has shown that supplementation with low does of a type of vitamin D, calcitriol, can reduce elevated PTH levels and in some cases help slow the progression of CRF.
Just as in humans, hypertension in pets can be controlled with medication. Unlike humans, it can be very difficult to get an accurate assessment of a dog or cat's resting blood pressure. This makes both the initial diagnosis and amount of medication to dispense challenging. Medications used for treating high blood pressure are also effective in treating another complication, excess protein in the urine.
A pet with CRF may make less of the hormones necessary for red blood cell production and become anemic. One treatment for anemia is to give human erythropoietin. Unfortunately, there are differences between the human and the canine and feline variants of erythroproietin. Over time this can lead to a pet developing antibodies that cause the human erythropoietin to be rejected.
Because the potential complications are so numerous, regular monitoring of blood composition and other symtoms is crucial so that additional actions can be taken in the most timely and effective manner as necessary. Pets that also suffer from heart disease pose a significant challenge as medications used to treat many heart problems can be contra indicated for treatment of kidney disease.
As you can see, there is no magic bullet in the treatment of CRF. By catching the disease early, diet modifications offer the best chance to slow its progression.