PRE-ANESTHETIC BLOODWORK IN A HEALTHY WEIMARANER PUPPY

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1 Volume 10 Issue 1 January 2018 Clinical Consults What s Your Diagnosis? PATIENT HISTORY SIGNALMENT: Victoria is an 11 month old spayed female Weimaraner dog. Weight 54 lb/24.5 kg. PERTINENT PAST HISTORY: Victoria has been a relatively healthy puppy. She completed the recommended puppy vaccination series. At 3 months of age she experienced a mild episode of hypertrophic osteodystrophy (HOD) in her carpal joints characterized by a moderate fever and mild to moderate lameness in both front limbs. Radiographs revealed the typical radiolucent line in the metaphysis parallel to the epiphyseal plates. Bloodwork at that time was completely normal and included a BUN of 13 mg/dl (ref. range mg/dl) and creatinine of 0.3 mg/dl (ref. range mg/dl). Victoria was started on carprofen to help with the inflammation associated with her HOD. She became fever and pain-free in just a few days and the carprofen was discontinued within two weeks. Victoria has had no recurrence of lameness or HOD signs. Victoria eats a commercially available dry large breed puppy food. She is given no supplements. She receives regular prophylactic deworming and heartworm preventatives as recommended by her veterinarian. CURRENT HISTORY: At 9 months of age, Victoria presented to a non-vca hospital for pre-anesthetic blood work in preparation for her ovariohysterectomy. Her CBC was unremarkable and Table 1 outlines her measured chemistry values. PRE-ANESTHETIC BLOODWORK IN A HEALTHY WEIMARANER PUPPY Beware of Normal Creatinine! Donna J. Spector, DVM, DACVIM, Internal Medicine TABLE 1. VICTORIA S SERUM CHEMISTRY (non-vca hospital) BUN (ref. range 9-31 mg/dl) Creatinine (ref. range mg/dl) SDMA (ref. range 0-14 ug/dl; 0-16 ug/dl in puppies) Phosphorus (ref. range mg/dl) 6.8 Calcium (ref. range mg/dl) 11 Albumin (ref. range g/dl) 2.6 Globulin (ref. range g/dl) 2.7 Total protein (ref. range g/dl) 5.3 ALKP (ref. range u/l) 41 CK (ref. range u/l) normal 1.5 normal 15 normal There was a clinical note from the laboratory which stated: Both SDMA and creatinine are within the reference interval which indicates kidney function is likely good. Evaluate a complete urinalysis and confirm there is no other evidence of kidney disease. Despite this note, Victoria s regular veterinarian was concerned about her renal parameters. Her veterinarian was aware of the International Renal Interest Society (IRIS) staging guidelines

2 ( which recognize renal azotemia may begin with blood creatinine concentrations lower than most reference ranges 1.4 mg/dl in the dog. The fact that Victoria was only 9 months old was also concerning as her creatinine should be lower than the normal adult reference range due to the relatively increased glomerular filtration rate (GFR) in puppies. Clinical Note: It should be expected for puppies to have creatinine values < 1 mg/dl - and typically mg/dl - until close to 1 year of age. Victoria s creatinine had been 0.3 mg/dl 6 months prior (during her HOD episode), so a creatinine of 1.5 mg/dl was a significant increase. While a gradual progressive decline in GFR is normal in the growing puppy and we do not want to over-interpret this as the development of kidney disease, Victoria s TABLE 2. CLINICAL CHEMISTRY OF PUPPIES Protein (albumin, globulin, coagulation proteins) ALKP, ALT, GGT Calcium/Phosphorus CK (Creatine Kinase) BUN Creatinine 1.5 mg/dl creatinine is just too high for such a young dog. Table 2 outlines the most commonly expected normal alterations on the clinical chemistry of puppies compared to adult reference ranges. Causes of an elevated serum creatinine concentration which are unrelated to renal dysfunction include a high muscle production of creatinine, dehydration and increased intestinal absorption of exogenous creatinine (i.e., high protein/cooked meat diet). Victoria s owner was questioned about her diet and she had not been receiving a large amount of meat or high protein foods. Although Victoria is a large breed dog, she is very thin and not highly muscled so this was considered an unlikely etiology of her increased serum creatinine concentration. Victoria had Protein levels in puppies are lower than adult reference ranges. Total protein concentrations gradually increase to achieve adult levels by 6 months to 1 year of age due to improved hepatic function, intestinal absorption of amino acids and immune stimulation. Puppies may have ALKP values up to 4x normal adult values. ALKP is an inducible enzyme synthesized by liver, osteoblasts and other tissues. Bone growth in young puppies is responsible for most of the ALKP elevation. ALT activity is lowest in puppies < 8 weeks of age and then increases to adult levels by approximately 6 months. GGT values can be markedly increased in young puppies and indicates passive transfer of colostrum in puppies. Adult values are obtained by approximately 6 months of age. Calcium and phosphorus levels are highest in puppies less than 8 weeks of age and adult levels are reached by 1 year of age. CK is highest in young animals due to normal development of musculature. CK is highest in puppies less than 3 months of age and then decreases to about 2x adult values at 6 months of age. Adult values are expected by 7-12 months of age. BUN is consistently lower in young animals as compared to adults. This is likely due to increased plasma volume after birth along with immature hepatic production or increased protein synthesis due to growth hormone influence. BUN is decreased in puppies 2 weeks to 3 months of age and then gradually rises to adult values by approximately 6-12 months of age. Young animals are expected to have lower creatinine relative to adults due to smaller body size and decreased muscle mass from which it is derived. Creatinine gradually increases from 8 weeks of age and normal adult values are expected by 1 year of age. not been fasted for the blood sample and her hydration status was considerred normal. Her owner was asked to drop off a urine sample the following day. The free-catch urinalysis revealed a urine specific gravity of with 3+ ( mg/dl) protein. There were 6-10 WBC/hpf and no hematuria. Although no bacteria were identified, Victoria returned the following day for a cystocentesis urine sample for both urinalysis and aerobic culture. The urine sample collected via cystocentesis revealed a urine specific gravity of 1.024, 3+ proteinuria, 0-2 WBC/hpf, 0-2 RBC/hpf and 2+ fine granular casts. There was no bacterial growth on aerobic culture. Most likely the WBC noted on the free-catch sample originated from the genital tract. Due to the marked proteinuria (3+ on both samples), the owner was instructed to collect separate urine samples for 3 days at home. Clinical Note: Due to large day to day variation in proteinuria, multi-day urine collections are advised to determine an accurate assessment of a dog s true level of proteinuria. The samples are stable at refrigerated temperatures for up to one week. One milliliter was obtained from each sample and pooled for a urine protein:creatinine ratio (UPCR). The UPCR was moderately elevated at 3.8. Clinical Note: Normal dogs have a UPCR <0.2. A UPCR >2 is strongly suggestive of glomerular proteinuria, as opposed to tubular proteinuria. REFERRAL EXAM & ADDITIONAL DIAGNOSTICS Victoria was referred for additional workup of her proteinuric renal disease. A hereditary nephropathy, renal dysplasia or an inflammatory glomerulonephritis (GN) were the primary rule outs. Given Victoria s history of HOD as a 3 month old puppy, there was concern about the possibility of inflammatory or immune mediated GN. GN can be associated with a number of diseases including various infectious, inflammatory and neoplastic conditions (see Table 3). However, approximately 50% of dogs with GN have idiopathic or primary GN. Victoria had also received carprofen during the HOD episode. Although carprofen is more sparing of COX-1 and associated with lesser

3 TABLE 3. DISEASES ASSOCIATED WITH GLOMERULONEPHRITIS IN DOGS INFECTIOUS INFLAMMATORY NEOPLASTIC OTHER Anaplasmosis Babesiosis Bacterial endocarditis Bartonellosis Blasto/coccidioidomycosis Borreliosis Brucellosis Ehrlichiosis Hepatozoonsois Heartworm disease Leishmaniasis Heterobilharzia Pyelonephritis Leptospirosis Pyometra Chronic bacterial infections Pancreatitis Cholangiohepatitis Periodontal disease SLE Polyarthritis IBD Other immune mediated disorders Hemangiosarcoma Hepatocellular carcinoma Leukemia Mast cell tumor Lymphoma Transitional cell carcinoma Bronchogenic adenocarcinoma Corticosteroid usage Diabetes mellitus Hyperadrenocorticism side effects, renal tubular damage is a documented side effect. Victoria s serum BUN and creatinine measurements prior to usage of carprofen had indeed been normal, so NSAID-induced renal injury was maintained as a possibility. The owners were questioned and due to extensive outdoor/wooded area exposure, a complete tick evaluation (PCR and serology), including Lyme serology was performed. All results were negative. Leptospirosis antibody serology was also negative. As hypertension occurs in a high percentage of patients with glomerular disease, Victoria s blood pressure was checked and was normal. Abdominal ultrasound imaging was recommended to evaluate her kidneys. Her kidneys were slightly small with hyperechoic cortices. There was no pelvic dilation, cortical cysts or other obvious abnormalities. The rule outs included inflammatory nephritis/glomerulonephritis. It was recommended that Victoria proceed with an ovariectomy (OE) procedure and also have multiple renal cortical biopsies obtained during the surgery. Immediately prior to her biopsy, Victoria s measured BUN was 48 mg/dl, creatinine 1.5 mg/dl, and albumin 2.6 g/dl. She underwent laparoscopic ovariectomy. The surgeon reported her kidneys appeared grossly normal and 4 biopsies from the left kidney and 2 biopsies from the right kidney were obtained under laparoscopic guidance. The renal biopsies were submitted to the International Veterinary Renal Pathology Service (IVRPS) at The Ohio State University. See Table 4 for Victoria s renal biopsy results. DIAGNOSIS IRIS Stage 2 CKD, proteinuric, non-hypertensive Severe glomerular disease suspect renal maldevelopment or NSAID toxicity VICTORIA S TREATMENT Victoria recovered uneventfully from anesthesia and returned to her vigorous puppy demeanor. Victoria s bloodwork was checked 2 weeks after renal biopsy. Her BUN had increased to 53 mg/dl and the creatinine was 1.6 mg/dl. Her albumin had decreased from 2.6 g/dl to 2.1 g/dl and her total protein from 5.3 g/dl to 4.6 g/dl. Her phosphorus was still mildly elevated at 6.7 mg/dl. She had no evidence of edema and her owner reported a fantastic appetite and energy level. Victoria was started on a number of therapies in attempts to support her renal function. Clinical Note: In 2013, the ACVIM published Recommendations for Standard Therapy of Glomerular Disease in Dogs. Please also refer to the December 2016 VCA Clinical Consult for a full detail of these and other recommendations for glomerular disease management. Victoria was started on polyunsaturated fatty acids (omega-3 s) due to their intra-renal anti-inflammatory properties as well as a renal diet. Although Victoria is only 10 months old, the benefits of the renal diet outweighed any possible negative impact. Victoria was also started on benazepril 7.5 mg PO BID (dosage of 0.3 mg/kg PO BID) to address and hopefully reduce her proteinuria. Clinical Note: The ACE inhibitors reduce proteinuria by reducing intra-glomerular hypertension via vasodilation of the postglomerular arterioles. Benazepril was chosen as it is cleared via both renal (45%) and hepatic (55%) routes as opposed to enalapril which is 95% cleared by renal mechanisms. Victoria was monitored closely as ACE inhibitors may result in worsening renal dysfunction and hyperkalemia. Ten days after starting the renal diet, omega-3 fatty acids and benazepril, the BUN had decreased to 36 mg/dl (from 53 mg/dl) and her creatinine was stable at 1.6 mg/dl.

4 TABLE 4. VICTORIA S RENAL BIOPSY RESULTS Specimens received: Needle biopsy specimens appropriately processed for light microscopy (LM), transmission electron microscopy (TEM) and immunofluorescence (IF) evaluations were received in good condition on 12/13/17. Morphologic Diagnosis: Severe glomerular hypertrophy and glomerulocystic atrophy; mild multifocal interstitial fibrosis and tubular atrophy with interstitial nephritis Pathologic Findings Light Microscopy (LM): Two cylindrical biopsy cores of renal cortex are examined. Both cores are partial cortex and medulla. There are 10 glomeruli, only one of which is within normal limits. The remaining glomeruli are characterized by markedly dilated Bowman s capsules with small glomerular tufts. One of these glomeruli has hemorrhage into Bowman s space. A few glomeruli are subjectively enlarged (hypertrophied). One glomerulus has marked peri-glomerular fibrosis which surrounds a narrowed junction between the proximal tubule and Bowman s capsule. There is marked interstitial fibrosis which surrounds atrophied tubules. Chronic interstitial inflammation is also present within these regions. Pathologic Findings Immunostaining (IF): The sample was sectioned entirely and it was medulla. There were no glomeruli available for evaluation. Pathologic Findings Electron Microscopy (TEM): Two glomeruli are available for ultrastructural evaluation. One of the glomeruli has a severely dilated Bowman s capsule and a compressed, wrinkled glomerular tuft (glomerulocystic atrophy). In this glomerulus, there are small segments of podocyte foot process effacement. The other glomerulus has patent capillary loops covered by healthy podocytes with intact foot processes. Electron-dense deposits are not identified along capillary loops or in mesangial zones. There is no evidence of abnormal glomerular basement membranes. Interpretation/Comments: The glomerular lesions are severe and advanced. There is glomerular enlargement which indicates that these glomeruli have undergone compensatory hypertrophy because there is decreased functioning nephron mass. Glomerulocystic atrophy occurs when Bowman s capsules detach from the proximal tubules, which is a lesion identified in this case. The hypertrophy and the glomerulocystic change are the cause of the proteinuria. These lesions are suggestive of either renal maldevelopment or an injury that happened months ago. This type of lesion could be the end result of NSAID toxicity. If NSAID toxicity resulted in significant tubular damage, the Bowman s capsule could have detached from the proximal tubules, eventually resulting in glomerulocystic atrophy. Although the IF specimen did not contain glomeruli for evaluation, these types of lesions are not commonly associated with immune complex deposition. Additionally, the TEM sample did not identify electron-dense deposits along the capillary walls so this is not a case of immune complex disease. As there is no evidence of abnormal glomerular basement membranes, this is not suggestive of hereditary nephritis (canine Alport syndrome). Clinical Note: The fibrosis and glomerulocystic atrophy are irreversible lesions. Given the young age of the patient and the fact that she is already mildly azotemic, the long term prognosis for the renal function of this patient is poor. Albumin had also remained stable at 2.1 g/dl instead of declining further. Blood pressure remained normal. Victoria is going to be closely monitored and adjustments in her medication will be made according to follow-up UPCR measurements. The ideal therapeutic target for ACE-inhibition is a reduction of the UPCR to <0.5 without inappropriate worsening of renal function. As this target is not terribly realistic in Victoria s case given the severe and advanced underlying disease process, a UPCR reduction of 50% (or greater) can hopefully be achieved. Once the maximum dosage of benazepril is reached, consideration will also be given to the addition of an angiotensin receptor blocker (such as losartan or telmisartan) to further reduce proteinuria as these medications often work better together to reduce proteinuria in dogs with glomerular disease. Victoria has an incredibly motivated owner and she will be heading to The Animal Medical Center in New York City in February 2018 to receive renal intra-arterial mesenchymal stem cell therapy to help combat her progressive renal failure. DISCUSSION A detailed discussion of proteinuric glomerular disease and renal dysplasia are beyond the scope of this article and the reader is referred to the listed references. As I was writing this report, I realized how fortunate Victoria was to have had such an astute veterinarian who was knowledgeable about the new normal creatinine parameters and IRIS guidelines which recognize renal azotemia is often present at serum creatinine concentrations lower than most laboratory reference ranges. Clinical Note: This value is 1.4 mg/dl for dogs and 1.6 mg/dl for cats. Creatinine is the most commonly used serum biomarker of glomerular filtration rate (GFR) in dogs and cats. Creatinine is produced from the non-enzymatic degradation of creatine and creatine phosphate in skeletal muscle and therefore serum creatinine concentrations reflect both the patient s muscle mass as well as GFR. While creatinine is very useful, some limitations have to be kept in mind. The first is, the relationship between creatinine and glomerular filtration rate (GFR)

5 is curvilinear, therefore, GFR can decrease rapidly in the early stages of kidney disease without any obvious increase in serum creatinine concentration. If there is an increase in creatinine, it is likely to be small and still within a laboratory s normal reference range - which is generally between 0.5 and 2 mg/dl depending on the reference laboratory. For example, a dog like Victoria who experienced an increase in serum creatinine from 0.3 to 1.5 mg/dl over a 6 month period (without evidence of dehydration, although there was some increase in muscle mass from growth), likely indicates a >50% reduction in GFR despite the fact that the serum creatinine remains within the reference range. Similarly in later stages of kidney failure, even a modest decrease in GFR will lead to a marked, rapid increase in serum creatinine concentrations. This is depicted visually in Figure 1 which is a table obtained from the IRIS website. Clinical Note: While SDMA may add to the picture as it is stated to be more sensitive than creatinine for detection of early kidney disease, it also is an imperfect test as evidenced by Victoria s normal results even in the face of biopsy-proven advanced glomerular disease. Serum symmetrical dimethylarginine (SDMA) is derived from intranuclear methylation of L-arginine by protein-arginine methyltransferases and released into the circulation after proteolysis. SDMA is eliminated primarily by renal clearance and represents a potential biomarker for diagnosing and monitoring kidney disease. A study performed in dogs who developed kidney disease revealed SDMA concentrations increased above normal approximately 17 months prior to blood creatinine concentration increasing above the reference range (> 1.8 mg/dl). Clinical Note: If a veterinarian considers a lower normal serum creatinine concentration of < 1.4 mg/dl in dogs, both creatinine and SDMA perform similarly in identifying early renal azotemia. The next important point Victoria s case highlights is the importance of obtaining renal biopsies and having biopsy tissue processed properly and evaluated by a pathologist well versed in renal pathology. Renal biopsy is the gold standard for determining the cause of proteinuric renal diseases in dogs FIGURE 1 RELATIONSHIP BETWEEN BLOOD CREATININE CONCENTRATION AND GFR and is utilized to direct treatment of these conditions. Renal biopsies should not be obtained in every proteinuric dog. Dogs who are affected by IRIS stage 4 CKD or those with concurrent contraindications (such as uncontrolled hypertension, marked anemia, etc.) are not good biopsy candidates. Additionally, if the result of the biopsy is unlikely to alter treatment, outcome or prognosis, it is not advised. However, in a patient like Victoria, a renal biopsy has much to offer, but must be performed and submitted correctly. To facilitate accurate classification of glomerular diseases, renal biopsy specimens should be evaluated by light microscopy (LM), immunofluorescence (IF) and transmission electron microscopy (TEM). Each of these techniques requires special handling and medium. The International Veterinary Renal Pathology Service (IVRPS) is a collaborative effort between Ohio State University and Texas A&M University and they offer biopsy kits and these services for renal biopsy specimens. Submission of renal biopsy specimens to a reference laboratory without these services is not recommended. A recent study published in JAVMA (Jan 2018) by the IVRPS group outlines important information for obtaining meaningful renal biopsy specimens. Findings suggested that ultrasoundguided renal biopsies (performed by someone skilled with the procedure) with a 16-gauge biopsy needle should maximize the diagnostic quality of renal biopsy specimens from dogs with suspected kidney disease, while avoiding potential adverse effects caused by larger needles. In this paper, ultrasound-guidance was preferred over laparotomy or laparoscopy as the latter biopsies were associated with a larger amount of renal medullary tissue, compared to the desired cortical tissue. Clinical Note: Someone well trained in laparoscopic techniques will generally procure excellent renal biopsy specimens and this technique should not be considered inferior to other biopsy techniques. The 16-gauge needle out-performed the samples obtained with 18-gauge needles in that there were consistently more glomeruli present. The ideal number of glomeruli for an accurate diagnosis of glomerular disease is >10 for LM, 4-8 for IF and 2-3 for TEM. As only approximately 54% of core specimens in this study obtained with 16-gauge needles included >10 glomeruli, IVRPS recommends at least 2 good quality renal core specimens be submitted for evaluation. The third point I would like to highlight with Victoria s case is a new therapeutic option for some canine glomerular diseases. Proteinlosing kidney disease, also called PLN, is the leading cause of renal disease in dogs and is

6 usually associated with one of two forms: membranoproliferative glomerulonephritis and membranous nephropathy. Renal biopsy is used to diagnose and then direct specific immunosuppressant or anti-inflammatory treatment of these conditions. While there are therapies that can be targeted against immunecomplex deposition and the inflammatory infiltrates causing PLN, overall outcomes in dogs affected by PLN are generally poor. Traditionally, dogs with azotemia at the time of diagnosis of PLN are expected to survive less than 3 months. A more recent study of 234 dogs with PLN found the median survival time for dogs with creatinine >1.5 mg/dl was only 13 days versus a normal creatinine with PLN was 407 days. Given this fairly dismal outlook for PLN, researchers have been investigating alternative approaches for slowing disease progression. One such approach is the use of adipose-derived mesenchymal stem cell (MSC) therapy to aid in nephron repair, improvement of nephron function, decrease renal fibrosis and ultimately slow the progression of PLN in dogs. MSC are multipotent cells that reside in various parts of the body like fat and bone marrow. These cells are capable of differentiating in vitro and in vivo into different cell types. They are attractive candidates for renal repair because nephrons are of mesenchymal origin and stromal cells are of crucial importance for signaling which can lead to the differentiation of both nephrons and collecting ducts. MSC have a natural homing capacity which means once they are injected, the cells travel to and become trapped in the capillary beds of diseased tissue. Clinical Note: When MSC are injected systemically (into a peripheral vein), they will not be delivered directly to the kidney, but instead will home to all areas of the body with concurrent inflammation after undergoing a first pass through the pulmonary capillary beds. Dr. Allyson Berent at The Animal Medical Center in New York City has been investigating the usage of both peripherally-injected and intra-arterially injected MSC directly into the renal artery. With intra-arterial injection, the first capillary bed to engraft the MSC is the glomerular tuft and vast blood supply of the diseased nephrons which has led to more dramatic results in improvement of renal function. A pilot study of MSC was performed in dogs affected by PLN. The study showed that MSC was safe and intra-arterial delivery was met with very few complications. The studies are ongoing but the initial data suggests MSC therapy coupled with conventional therapy is improving renal function based on biochemical data (e.g., GFR studies, serum creatinine/phosphorus levels, proteinuria), reducing mortality from renal failure, reducing all-cause mortality, is safe and appears to improve the quality of life compared with animals treated only by conventional therapy. Additionally, it appears MSC therapy delivered via renal arterial injection will prolong survival compared with animals receiving MSC through peripheral vein injection. I will keep you updated as to Victoria s progress after her intra-arterial MSC injections! REFERENCES Crivellenti, LZ, R Cianciolo, T Wittum, et al. Associations of patient characteristics, disease stage, and biopsy technique with the diagnostic quality of core needle renal biopsy specimens from dogs with suspected kidney disease. JAVMA Vol 252, No 1. January 1, Lees, GE. Familial Renal Disease in Dogs. Chapter 315. The Textbook of Veterinary Internal Medicine, Ettinger and Feldman editors, 7th edition, Elsevier, St. Louis, Vaden, SL. Glomerular Diseases. Chapter 312. The Textbook of Veterinary Internal Medicine, Ettinger and Feldman editors, 7th edition, Elsevier, St. Louis, International Renal Interest Society website: International Veterinary Renal pathology Service. IRIS Canine GN Study Group Standard Therapy Subgroup (S. Brown, J. Elliott, T. Francey, D. Polzin, and S. Vaden). Consensus Recommendations for Standard Therapy of Glomerular Disease in Dogs. JVIM 2013; 27: S27-S43. Gorman, ME. Clinical chemistry of the puppy and kitten. Western Veteirnary Conference 2011, Proceedings.

7 CLINICAL ASSESSMENT 1 Which of the following clinical chemistry changes can be expected as a normal puppy phenomenon? a. Mild to moderate hypoalbuminemia b. Elevated GGT c. Decreased BUN and creatinine d. Elevated CK e. All of the above 2 Puppies should have a higher creatinine than an adult dog due to the robust muscle growth that occurs during puppyhood. True or False? 3 Which of the following may result in an increased serum creatinine? a. Dehydration b. High protein diet c. High muscle production of creatinine d. Renal dysfunction e. All of the above 4 5 A single free-caught urine sample is ideal for monitoring proteinuria. True or False? What magnitude of proteinuria is normal? Consistent with tubular proteinuria? Consistent with glomerular proteinuria? 6 How do ACE-inhibitors reduce proteinuria and what are the potential serious side effects? 7 The ideal therapeutic target for ACEinhibition is reduction of the UPCR to <0.5 without inappropriate worsening of renal function. True or False? 8 There is a wide range for normal serum creatinine concentrations at reference laboratories. What does IRIS recommend as a more reasonable creatinine reference range for detecting early renal disease in canine and feline patients? Renal biopsy specimens are best collected 9 during open laparotomy using a wedge biopsy technique. True or False? Which of the following is critical for the 10 diagnosis and proper classification of canine glomerular diseases? a. Light microscopy b. Immunofluorescence c. Transmission electron microscopy d. All of the above The prognosis for canine glomerular 11 disease is fair to good. True or False? 12 Mesenchymal stem cells are showing promise to aid in slowing the progression of PLN in dogs. True or False?

8 CLINICAL ASSESSMENT ANSWERS: 1. E. All of the above. Protein concentrations gradually increase to achieve adult levels by 1 year of age due to improved hepatic function, intestinal absorption of amino acids and immune stimulation. The decreased BUN is due to immature hepatic production or increased protein synthesis due to growth hormone. Decreased creatinine is expected due to their smaller body size/decreased muscle mass as well as their higher glomerular filtration rate (GFR). CK is elevated due to normal development of musculature. 2. False. Puppies should have creatinine values less than adult dogs until close to 1 year of age. The expected creatinine value should be <1 mg/dl due to their inherently higher GFR. While a gradual progressive decline in the GFR is normal in growing puppies, the value should still remain generally < 1 mg/dl. 3. E. All of the above. If you obtain an unexpected creatinine elevation, it is important to question owners about potential dietary sources of creatinine and to be aware of breed creatinine differences (e.g. Greyhound with higher values). 4. False. Due to large day-to-day variations in proteinuria, multi-day (usually 3) urine collections are advised to determine an accurate assessment of a dog s true level of proteinuria. The samples are stable at refrigerated temperatures for up to one week. 5. Normal dogs have a UPCR <0.2. A UPCR is more consistent with tubular (or early glomerular) proteinuria. A UPCR >2 is strongly suggestive of glomerular proteinuria. 6. ACE-inhibitors reduce proteinuria by vasodilating the postglomerular arterioles which results in a reduction of intra-glomerular hypertension with a subsequent lessening of proteinuria. ACE-inhibitors do decrease GFR somewhat and worsening renal dysfunction is not uncommon. BUN and creatinine should be regularly rechecked when dogs are taking ACE-inhibitors. 7. True. This target is not realistic in many dogs with moderate to marked elevations of their UPCR. A secondary target is a 50% reduction of proteinuria without worsening of renal function. 8. Creatinine of 1.4 mg/dl and 1.6 mg/dl in dogs and cats, respectively should be used as the top end of the normal reference range. More thorough investigation including urinalysis, UPC, and imaging will likely be necessary to fully define renal disease. 9. False. Findings suggest ultrasound-guided renal biopsies (performed by someone skilled with the procedure) with a 16-gauge biopsy needle should maximize the diagnostic quality of renal biopsy specimens from dogs with suspected kidney disease, while avoiding potential adverse effects caused by larger needles. Ultrasound-guidance was preferred over laparotomy or laparoscopy as those biopsies were associated with a larger amount of renal medullary tissue, compared to the desired cortical tissue. At least 2 good quality renal core specimens be submitted for evaluation. 10. D. All of the above. All of these modalities give different information when classifying canine glomerular disease. It is important that renal biopsy specimens contain > 10 glomeruli for light microscopy, 4-8 for immunofluorescence and 2-3 for electron microscopy. 11. False. Traditionally, dogs with azotemia at the time of diagnosis of PLN were expected to survive less than 3 months. Due to increased screening and earlier diagnosis, many dogs are identified before they become azotemic and their median survival time is just over 1 year, however, this is still not a good prognosis. 12. True. MSC aid in nephron repair, improvement of nephron function, and decreasing renal fibrosis. Pilot studies and unpublished data suggest MSC therapy coupled with conventional therapy is improving renal function based on biochemical data (e.g. GFR studies, serum creatinine/phosphorus levels, proteinuria), reducing mortality from renal failure, reducing all-cause mortality, is safe and appears to improve the quality of life compared with animals treated only by conventional therapy. Additionally, it appears MSC therapy delivered via renal arterial injection will prolong survival compared with animals receiving MSC through peripheral vein injection.