Case Study: Chronic Renal Disease in a Dog



Case Study: Chronic Renal Disease in a DogSarra Borne LordTarleton State UniversityCA Nutrition and CareVETE 4323Dr. Mary CarpinoOctober 29, 2015Case Study: Chronic Renal Disease in a DogChuck is a ten-year-old, neutered male, Golden Retriever, who was presented with the complaint of acute onset polydipsia, polyuria, and accidents in the house. Chuck has been a patient since puppyhood and is up to date on vaccinations. Previous medical history includes a routine neuter, two laceration repairs, and several nail trims. The owner relates that Chuck’s appetite has decreased over the last week. For the past three years, Chuck has received the same food in the same quantity. The last few days, Chuck has not been finishing his food and has not been interested in treats. Chuck also appears to have less energy and is not as interested in playing. Chuck has vomited twice in the past week.Physical Examination:Rectal Temperature: 100.8oFHeart Rate: 90 beats per minuteRespiratory Rate: 24 breaths per minuteWeight: 78 pounds (decreased from 88 pounds at last exam nine months ago)Body Condition Score: 2.5/5Skin/Coat: muzzle white, coat dullOral Cavity: moderate dental tartarMusculoskeletal: decreased range of motion in hind limbs, not painfulGastrointestinal: Kidneys palpate small bilaterally with right smaller than leftBased on physical findings a urinalysis was ordered.Urinalysis:SourceFree CatchColor Pale YellowTurbidityClearSpecific Gravity1.010Blood NegativeGlucoseNegativeKetonesNegativepH6.0Protein+++BilirubinNegativeUrobilinogenNegativeSediment analysis No RBC, WBC or Crystals seen. Rare granular casts.After reviewing the urinalysis results, the veterinarian received consent to run a complete blood count and serum chemistry with electrolytes.CBC ParameterResultReference Range (IDEXX)RBC6.24 .8 – 9.3 x 106/uLHCT4138.3-56.5 %HGB12.613.4-20.7 g/dLMCV66.059 -76 fLMCHC30.632.6 – 39.2 g/dLWBC5.04 – 15.5 x 103/uLPlatelets500 143-448 103/uLChemistry ParameterResultReference RangeBUN98 H8-29 mg/dLCreatinine6.7 H0.8 – 1.5 mg/dLPhosphorus7.6 H2.5 – 6.1 mg/dLCalcium11.08.4 – 11.8 mg/dLSodium149142 – 152 mEq/LPotassium3.74.0 – 5.4 mEq/LChloride115108 – 119 mEq/LTotal Protein7.25.5 -7.5 g/dLALT7018 – 121 g/dLALKP505 – 160 U/LTotal Bilirubin0.20.0 – 0.3 mg/dLCholesterol320131 – 345 mg/dLAmylase1120337 – 1469 u/lGlucose9263 – 114 mg/dL After evaluating the information gained from the history, physical examination, and lab results, the veterinarian makes a clinical diagnosis of renal failure. The lab results show an elevation of the BUN or blood urea nitrogen. The BUN measures the by-products of protein metabolism that are normally excreted by the kidneys. If the kidneys are not working correctly and filtering out these waste products, they will build up in the blood. The lab results also show an elevation of creatinine that is a breakdown product of muscle and a measurement of the glomerular filtration rate of the kidneys. The kidneys are the only organs that excrete creatinine, and if there is an increased level of creatinine in the blood, it means that kidney function is impaired. The serum phosphorus level is elevated, which occurs when the kidneys fail to excrete excess amounts in the urine. The urine specific gravity showed that the urine is not being concentrated, and there is too much water being excreted. There are also large quantities of protein excreted in the urine that is an expected finding in some types of kidney disease. Finally, the presence of granular casts in the urine indicates that the kidneys are sloughing some of the cells that line the renal tubules. “If a cast is seen in the urine, kidney (renal) disease or involvement exists; the presence of casts indicates kidney (renal) disease rather than lower urinary tract disease (Ringsrud, 2001, p. 191). The veterinarian uses the IRIS staging system to put Chuck into Early Stage III Chronic Renal Disease. IRIS or the International Renal Interest Society was organized in 1998 with the mission of assisting veterinary practitioners better understand, diagnose and treat renal diseases in dogs and cats. IRIS has established internationally recognized clinical guidelines for the staging and treatment of renal disease. Chuck meets the criteria for Stage III because his blood creatinine is >2.8 mg/dL. However, his urine protein to creatinine ratio and his blood pressure would need to be evaluated for proper staging. Patients in IRIS Stage I and II may not have any clinical signs and are not yet azotemic, so their owners do not suspect that anything is amiss. IRIS Stage I and II may be detected in patients who receive regular senior pet evaluations if an upward trend is noticed in their blood urea nitrogen (BUN) and creatinine levels. By IRIS Stage III, approximately 75% of renal nephrons are non-functional, and clinical signs start to come to the fore. “With appropriate therapies, animals can survive for long periods of time with only a small fraction of functional renal tissue, perhaps 5 -8% in dogs and cats” (The Merck Veterinary Manual Online [Merck], 2013, p. 9). Azotemia is an increased concentration of non-protein nitrogenous compounds in the blood as measured by elevated BUN and creatinine levels. Azotemia can be pre-renal, renal or post-renal. Pre-renal azotemia occurs when the glomerular filtration rate (GFR) is decreased due to a disturbance in the circulatory system such as hypovolemia or cardiac disease. In pre-renal azotemia, the kidneys are still able to concentrate the urine as shown by a normal urine specific gravity with no evidence of protein in the urine. Post- renal azotemia results from urinary obstruction or rupture and clinical signs include frequent attempts to urinate with little to no production, or a distended abdomen due to the presence of urine in the abdomen (uroabdomen). Renal azotemia is diagnosed when the kidneys are no longer able to concentrate urine (USG 1.008 – 1.012), blood urea and creatinine levels are elevated above normal reference levels, and there are clinical signs of polyuria (increased urination) and polydipsia (increased thirst). The veterinarian prescribes enalapril and a prescription renal diet. There are several manufacturers that produce prescription renal diets for dogs and cats. Hill’s Pet Nutrition manufactures Hill’s Prescription k/d; Royal Canin manufactures Veterinary Diet Renal Support, and Purina ProPlan Veterinary Diet manufactures NK Kidney Function. All of these foods come in both canned and dry formulas. They are all designed to provide a reduced level of high-quality protein, restricted sodium and phosphorus levels, and added B-complex vitamins. Providing a reduced level of high-quality protein will help meet Chuck’s nutritional requirement for protein while attempting to decrease the workload of his kidneys by avoiding excessive nitrogenous waste. Patients with kidney disease cannot eliminate excess sodium and fluid from the body efficiently. Excessive amounts of sodium can contribute to hypertension (high blood pressure), and the build-up of fluid (edema). Hypertension can result in greater damage to the kidneys, and edema can contribute to heart failure. Normal kidneys can process phosphorus, but during chronic renal disease, the damaged kidneys cannot remove phosphorus from the bloodstream very efficiently. Excessive dietary phosphorus that isn’t excreted can start to pull calcium out of the bones making them weaker. The increase in B-vitamins is to replace the larger amount of water soluble vitamins excreted because of Chucks increased urinary frequency. In addition to a prescription renal diet, Chuck should always be allowed access to fresh water. Pets with renal disease are at risk for dehydration because their bodies cannot concentrate their urine output which means they are losing a large amount of water that would be retained in a pet with normal renal function. Chuck’s owner chooses to try Hill’s Prescription Diet k/d dry food. It has 398 kcal/cup. Chuck weighed 88 pounds when he was healthy nine months ago. At 88 pounds, Chuck’s resting energy requirement would be 1113 kcal/day. According to the estimated energy requirement calculator, an average, neutered adult has a maintenance daily energy requirement factor of 1.6. Chuck’s daily energy requirement is approximately 1780 kcal/day. He should receive about 4.5 cups of dry k/d per day split into 2 or more meals. His owner should introduce the Hills k/d gradually over a week’s period by slowly increasing the amount of k/d and reducing the amount of his usual diet until he is only eating k/d. Introducing the new diet slowly will help prevent gastrointestinal upset. Chuck will need rechecks every four months to monitor the progression of his disease. At each visit his physical condition and weight will be monitored, his blood values and blood pressure will be evaluated, and drug therapy will be instituted as needed. Renal disease is not curable; numerous steps can minimize the symptoms and slow the progression of the disease. Chuck’s owner should monitor him for anorexia, dehydration, mouth ulcers, bad breath, increased lethargy, pale gums, vomiting, and diarrhea. Any of these can indicate a worsening of his symptoms. Chuck’s owner should keep track of food and water consumption and watch for a decrease in either. If Chuck is not drinking enough water, he will need additional fluids to prevent dehydration. Monitoring his weight will ensure he is receiving enough calories to maintain his weight at a healthy level. ReferencesFoster, J. D. (2013, September/October). Canine chronic kidney disease: Current diagnostics and goals for long-term management. Today’s Veterinary Practice, 21-26. Retrieved from Renal Interest Society. (2013). IRIS staging of CKD. Retrieved from , K. M. (2001, April). Casts in the urine sediment. Laboratory Medicine, 32(4), 191-193. Retrieved from , J., & Christensen, C. (2010). Case studies in veterinary technology: A scenario-based critical thinking approach. Heyburn. ID: Rockett HouseThe Merck Veterinary Manual Online. (2013). Renal dysfunction in small animals. Retrieved October 29, 2015, from ................
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