small animal med- chronic kidney disease

what is chronic kidney disease?

progressive tubulointerstitial disease

CKD is an umbrella term to describe any renal dz that leads to progressive loss of kidney function over time

what is the SDMA and creatinine of a cat with stage 1 CKD?

SDMA: less than 18

creat: less than 1.6

what is the SDMA and creatinine of a cat with stage 2 CKD?

SDMA: 18-25

creat: 1.6-2.8

what is the SDMA and creatinine of a cat with stage 3 CKD?

SDMA: 26-38

creat: 2.9-5.0

what is the SDMA and creatinine of a cat with stage 4 CKD?

SDMA: greater than 38

creat: greater than 5.0

what is the SDMA and creatinine of a dog with stage 1 CKD?

SDMA: less than 18

creat: 1.4

what is the SDMA and creatinine of a dog with stage 2 CKD?

SDMA: 18-35

creat: 1.4-2.8

what is the SDMA and creatinine of a dog with stage 3 CKD?

SDMA: 36-54

creat: 2.9-5.0

what is the SDMA and creatinine of a dog with stage 4 CKD?

SDMA: greater than 54

creat: greater than 5.0

how does azotemia differ between stages 1-4 CKD?

stage 1: no azotemia (normal creat)

stage 2: mild azotemia

stage 3: moderate azotemia

stage 4: severe azotemia

what are the UPC substage values for cats with CKD?

nonproteinuric: <0.2

borderline proteinuric: 0.2-0.4

proteinuric: >0.4

what are the UPC substage values for dogs with CKD?

nonproteinuric: <0.2

borderline proteinuric: 0.2-0.5

proteinuric: >0.5

what blood pressure values correlate with hypertension in cats and dogs with CKD?

normotensive: <140mmHg

pre-hypertensive: 140-159mmHg

hypertensive: 160-179mmHg

severe hypertension: >180mmHg

what should be done after an animal is diagnosed with CKD?

look for underlying etiology and treat accordinly:

-discontinue nephrotoxic drugs if possible

-treat pre-renal (dehydration) and post-renal abnormalities if applicable

-rule out treatable conditions

what is the minimum diagnostic database needed after diagnosing CKD in an animal?

-abdominal imaging (rads and/or U/S)->uroliths?

-blood pressure (hypertension?)

-UPC ratio (proteinuria?)

what test should be done if active urine sediment with signs of lower urinary tract disease is seen on urinalysis?

submit a urine culture

which testing should be performed if an animal with CKD has proteinuria?

consider infectious disease testing

what is the minimum infectious disease testing that should be done in dogs and cats with proteinuria?

cats: POC FeLV/FIV test

dogs: ehrlichia canis and borrelia burgdorferi antibody tests

when should CKD testing be performed?

following diagnosis of CKD

what is CKD staging based on?

based on fasting blood creatinine and/or SDMA on at least 2 occasions in a hydrated, stable patient

what is CKD substaging based on?

UPC ratio and blood pressure

which renal conditions can IRIS CKD staging not be applied to?

IRIS staging cannot be applied to:

-pre- or post-renal azotemia

-acute or decompensated (acute on chronic) kidney disease

what are the treatment goals for stages 1 and 2 CKD?

-slow progression of CKD by preserving remaining kidney function for longer

-provide sufficient energy to maintain body weight

what are the treatment goals for stages 3 and 4 CKD?

-improve quality of life and reduce signs of uremia

-manage fluid, electrolyte, and acid-base disturbances

what are the 8 management targets of CKD?

1. dehydration

2. hyperphosphatemia

3. hyperkalemia (dogs), hypokalemia (cats)

4. proteinuria

5. anemia

6. systemic hypertension

7. nausea, vomiting, weight loss

8. constipation

which of the management targets for CKD can be managed with diet?

-dehydration

-hyperphosphatemia

-potassium imbalances

-proteinuria

diets play a large role in managing CKD

what are the general concepts of renal therapeutic diets?

-restricted in phosphorus (sometimes low)

-restricted in protein (sometimes low)

-high caloric density

-restricted sodium

-alkalinizing

-omega-3 fatty acids

-variable potassium

what are the benefits of restricting phosphorus in renal diets?

lowers FGF-23 and PTH concentrations

what are the benefits of restricting protein in renal diets?

reduces uremic toxin production and improves proteinuria

less protein= less conversion to urea

what are the benefits of high caloric density in renal diets?

increases caloric intake and prevents weight loss

what are the benefits of low sodium in renal diets?

prevents sodium loading and worsening polyuria

what is the benefit of renal diets being alkalinizing?

treats metabolic acidosis

what are the benefits of omega-3 fatty acids in renal diets?

has anti-inflammatory effects, treats proteinuria

what is the only way you can compare renal diets?

by caloric/energy density

why can you not compare foods/diets with the guaranteed analysis?

because the nutrient amount given on an as fed basis, and does not take into account the caloric density or moisture content of food

what is the difference between diets formulated for stages 1 and 2 CKD and diets formulated for stages 3 and 4 CKD?

diets formulated for stages 1/2 CKD are higher in protein and phosphorus than diets formulated for stages 3/4

which animals should be placed on a renal diet?

-consider for animals with stage 2 CKD

-recommend for animals with stages 3 and 4 CKD

when should animals with stage 2 CKD be considered for a renal diet?

-signs of uremia (vomiting, poor appetite, weight loss)

-if fasted blood phosphorus is above IRIS target range

-if serum FGF-23 concentration is elevated (cats only)

should animals with stage 1 CKD be placed on a renal diet?

no consensus on this- often do not need protein restriction unless proteinuria is present

may need dietary phosphorus restriction if fasted serum phosphorus is above IRIS target or elevated FGF-23 (cats)

at minimum, what type of diets should animals with stage 1 CKD be fed?

diets with:

-moderate protein intake

-moderate dietary phosphorus intake

-senior diet from reputable science-based company (often meets moderate protein/phosphorus restrictions)

what happens if you feed highly restricted phosphorus renal diets to cats with early CKD?

can develop hypercalcemia (increasing dietary phosphorus usually resolves hypercalcemia)

develops within 6 months of transition onto renal diet

what is the highest priority in managing animals with CKD?

maintaining caloric intake

what can result if offering an animal exclusively a renal diet but the animal is not eating enough calories?

can lead to protein malnutrition and weight/muscle loss

must estimate maintenance energy requirement (MER)

how is MER calculated for CKD?

MER for CKD= RER x 1.0-1.4

RER=70 x (BW in kg)^0.75

what can you do when pets refuse a renal diet?

1. treat nausea and dysrexia (appetite stimulants, anti-emetics)

2. slowly transition to new renal diet (esp cats)

3. rotational feeding

4. entice pet to eat

5. supplement renal diet with senior diet

how is dehydration managed in animals with CKD?

1. increase free water intake

2. subcutaneous fluids

how can free-water intake be increased?

-canned food only (has much higher moisture content compared to dry)

-free access to water

at which stages of CKD are SQ fluids considered to manage dehydration?

usually for stages 3 or 4 CKD

use cautiously in animals with heart disease (especially cats)

which fluids should be administered for animals with stage 3/4 CKD for rehydration?

isotonic fluids: LRS most common (lower in sodium than norm-R)

what is the cause of hyperphosphatemia in animals with CKD?

consequence of reduced GFR

what can hyperphosphatemia lead to?

can lead to renal secondary hyperparathyroidism

associated with negative survival

what is the IRIS target serum phosphorus levels for CKD stages 2,3, and 4?

stage 2: <4.6mg/dL

stage 3: <5.0mg/dL

stage 4: <6.0mg/dL

what is the treatment for hyperphosphatemia in animals with CKD?

1. reduce dietary intake of phosphorus (most effective way- renal therapeutic diet)

2. reduce GI absorption of phosphorus (if persistent hyperP, start phosphorus binder)

3. monitor serum phosphorus every 2-4 weeks until IRIS target is achieved

what is the MOA of oral phosphorus binders?

inhibit dietary phosphorus absorption in GI tract- only works if given with food

what oral phosphorus binders are available?

1. aluminum hydroxide (most common- cats and dogs)

2. lanthanum (cats)

what is the etiology of hyperkalemia in dogs with CKD?

-reduced renal excretion

-drug side effect (from ACE inhibitor)

what CKD stage is hyperkalemia most commonly seen in dogs?

stage 3

what serum potassium concentrations in dogs with hyperkalemia warrants treatment?

K > 6.0mEq/L warrants treatment

what is the treatment for hyperkalemia in dogs with CKD?

reduce dietary potassium intake:

-look at current diet and switch to one lower in potassium

-recommend low K intake (may require home-cooked diet formulated by nutritionist)

what CKD stage is hypokalemia most commonly seen in cats?

stages 2 and 3

what is the etiology of hypokalemia in cats with CKD?

-inadequate oral intake (anorexic)

-vomiting

-urinary loss (polyuria) and decreased reabsorption

what are clinical signs of hypokalemia in cats?

when potassium in <3.0mEq/L:

-muscle weakness (cervical ventroflexion)

-PU/PD

-tachycardia

-constipation

-anorexia

what is the treatment for CKD cats with hypokalemia?

-increase dietary intake

-oral supplementation (potassium citrate (also helps with metabolic acidosis), potassium gluconate)

-maintain serum concentration in middle or upper halg of reference range

how does proteinuria seen in CKD differ between dogs and cats?

dogs: are first proteinuric, then later become azotemic

cats: are first azotemic, then later become proteinuric

when should renal proteinuria be suspected?

-pre-renal and post-renal causes are excluded

-hypoalbuminemia

-UPC >1 (cats) and >2 (dogs)

what is the treatment for proteinuria in CKD patients?

1. reduce dietary protein intake by 25-50%

2. daily EPA/DHA (omega 3 fatty acids)

3. RAAS inhibition

4. prevent thromboembolism in PLN cases (clopidogrel)

what type of anemia is usually seen in CKD patients?

normocytic, normochromic non-regenerative anemia

what is the etiology of anemia in CKD?

-reduced erythropoietin production by kidneys

-shortened RBC survival with uremia

when should anemia seen in CKD be treated?

any persistently documented anemia is worth treating

associated with a negative survival

what are the treatment options for treating anemia in CKD patients?

1. darbepoetin SQ injections (dogs and cats)

2. molidustat (Varenzin-CA1- cats only)

3. if severe, RBC transfusion (dog HCT <20%, cat HCT <15%)

what is the MOA of darbepoetin for treating anemia?

recombinant human EPO analogue (stimulates RBC production)

what is the MOA of molidustat (varenzin-CA1) for treating anemia in cats?

factor-prolyl hydroxylate inhibitor than increases transcription of EPO

what are side effects of varenzin-CA1?

vomiting

increasing systolic blood pressure

transient hyperkalemia

what is the normal blood pressure in healthy dogs and cats?

120-160mmHg

what is hypertension defined as?

hypertension= BP >160mmHg and/or evidence of target organ damage

how is systemic hypertension diagnosed?

indirect measurement:

1. doppler with sphymomanometer (more technically difficult but gives more reliable reading)

2. oscillometric (high definition recommended for cats)

when should fundoscopic exams be performed in patients with systemic hypertension?

fundoscopic exams should be done every time you do a blood pressure reading in a patient

can help determine if high blood pressure due to clinical stress or patient is truly hypertensive

what hypertensive lesions can be seen with fundoscopic exams?

retinal edema and retinal hemorrhage

what are signs of complete retinal detachement?

-mydriasis

-absent PLR

-blind

-if you see retina coming towards you on exam w/o lens

what is the treatment for systemic hypertension in dogs?

1. amlodipine (calcium channel blocker, causes vasodilation)

2. RAAS inhibition (ACE inhibitor or angiotensin receptor blocker- enalapril or telmisartan)

what is the treatment for systemic hypertension in cats?

1. amlodipine

2. telmisartan (angiotensin receptor blocker- works better than ACE inhibitors in cats)

why is weight loss closely monitored in animals with CKD?

body weight is associated with survival- lower BW=lower survival

what is the etiology of weight loss in CKD patients?

multifactorial:

-chronic inflammation

-protein malabsorption and malassimilation

-increased energy requirements

-decreased appetite

what is the treatment for nausea in animals with CKD?

mirtazapine (cats), ondansetron (cats and dogs)

what is the treatment for vomiting in CKD patients?

maropitant (cats and dogs)

what is the treatment for weight loss in CKD patients?

appetite stimulation:

-mirtazapine (cats)

-capromorelin as needed (cats and dogs0

which animals with CKD more commonly experience constipation?

cats

what is the etiology of constipation with CKD?

-dehydration

-hypokalemia

-reduced colonic motility

-phosphate binders

what is the treatment for constipation in CKD animals?

-correct hypokalemia and dehydration

-give warm water enema with sterile lube

prophylactic tx options: psyllium husk, osmotic laxative, cisapride

which animals with CKD are renal transplants most commonly done in?

most are done in young cats with congenital CKD:

-polycystic kidney disease

-amyloidosis

-renal dysplasia

what does the prognosis of CKD depend on?

depends on species and stage of disease

what is the overall MST of dogs with CKD?

overall MST= 174-226 days

what are the MSTs for dogs with stages 2-4 CKD?

stage 2 MST= 220 days

stage 3 MST= 180 days

stage 4 MST= 80 days

what are the MSTs for cats with stages 2-4 CKD?

stage 2 MST= 1151 days

stage 3 MST= 778 days

stage 4 MST= 103 days