The BUN, or blood urea nitrogen, is often tested as a measure of kidney function. Urea is one of the waste products that build up in the blood when the kidneys are not capable of performing adequately.
BUN is measured with a blood sample and is part of any routine blood chemistry screen. It may be elevated because of pre-renal causes such as dehydration and post-renal causes such as urinary tract obstructions as well as acute or chronic kidney disease.
Instructions
Perform a thorough physical examination. Perform a complete blood count, blood chemistry panel, urinalysis and urine culture. Measure and record the blood pressure.
Rule out pre-renal or post-renal disease as causes for the increase in BUN. Treat any non-renal causes appropriately. Leptospirosis and Lyme disease should also be considered. Test for these diseases if there is risk of exposure based on the dog's lifestyle.
If laboratory testing supports the presence of bacterial infection, institute appropriate antibiotics. Choose antibiotics based on culture and sensitivity results from urine or kidney biopsy when possible. In cases of suspected Lyme disease nephritis, treat with doxycycline. In suspected or confirmed cases of leptospirosis, a course of doxycycline followed by a course of a penicillin-based drug is indicated.
In the absence of bacterial disease, antibiotics are contraindicated.
Feed a renal diet low in sodium, phosphorus and protein. Numerous commercial diets are available. Home-cooked diets formulated with the aid of a veterinary nutritional expert can also be used.
Start fluid therapy depending on the degree of elevation in the BUN. If the animal is clinically dehydrated or if symptoms of uremic gastritis such as vomiting, lethargy and lack of appetite are present, administer fluid therapy immediately. Fluid therapy may be accomplished by intravenous administration or by subcutaneous (under the skin) administration. Intravenous administration allows more aggressive fluid therapy in the face of acute renal disease. However, subcutaneous fluid therapy can often be accomplished by owners at home. In cases of chronic renal disease, fluid therapy may need to be repeated periodically, with the frequency dependent on the reappearance of clinical signs. It is possible to begin with intravenous fluid therapy and switch to subcutaneous therapy once the dog is stable.
Measure the amount of fluid being given to the dog, both orally and through fluid therapy. Compare this value to the amount of urine that the dog is producing. If the dog is not producing adequate amounts of urine, administer a diuretic agent such as mannitol, dextrose or furosemide.