Heart Murmur, Incidental Finding

412 Heart Murmur, Incidental Finding

(asymptomatic) mitral valve regurgitation. Technician Tips Count Respirations and Monitor Respiratory Relevant inclusion criteria for the trial that Teaching owners to keep a log of their pet’s Effort) demonstrated this effect were a vertebral resting respiratory rates can allow early detection heart sum > 10.5, an echocardiographic left of HF decompensation so that medications can SUGGESTED READING atrial–aortic ratio > 1.6, and left ventricular be adjusted and hopefully hospitalization for Atkins C, et al: ACVIM consensus statement. enlargement. acute HF can be avoided. Guidelines for the diagnosis and treatment of • ACE inhibition may have a positive effect on canine chronic valvular heart disease. J Vet Intern the time to development of stage C HF in Client Education Med 23:1142-1150, 2009. canine patients with left atrial enlargement Management of the veterinary patient with AUTHOR: Jonathan A. Abbott, DVM, DACVIM due to mitral valve regurgitation. chronic HF requires careful monitoring and EDITOR: Meg M. Sleeper, VMD, DACVIM • Evidence that medical therapy slows the relatively frequent adjustment of medical progression of HCM is lacking. therapy (see client education sheet: How to

Client Education Heart Murmur, Incidental Finding Sheet

Initial Database BASIC INFORMATION rate or body posture), short (midsystolic), single (unaccompanied by other abnormal • Thoracic radiographs may be considered Definition sounds), and small (not widely radiating). as the initial diagnostic test in small- to A heart murmur that is detected in the process medium-breed dogs with systolic murmurs of an examination that was not initially directed Etiology and Pathophysiology that are loudest over the mitral valve at the cardiovascular system • A heart murmur is caused by turbulent blood region. flow in the heart (p. 414). • An echocardiogram should be considered Synonym • Identifying the timing, location, and intensity for any adult animal with one or more of Asymptomatic heart murmur of the murmur may be straightforward or the following: uncertain or unusual murmur Epidemiology challenging; uncertainty favors pursuing characteristics, murmur characteristics sug- diagnostic testing. gesting a form of heart disease that requires SPECIES, AGE, SEX • The presence of a heart murmur does not initiation of treatment, large-breed dog (aus- Any species, all ages, both sexes warrant treatment. Rather, determining its cultation and thoracic radiographs have low cause (definitively or presumptively) can lead to specificity for individual cardiac disorders), GENETICS, BREED PREDISPOSITION an assessment of whether treatment is indicated. impending cardiovascular stress (e.g., plane Predispositions mirror those of the causative travel, general anesthesia), breeding prospects,

cardiac diseases (pp. 263, 505, 657, 658, 764, DIAGNOSIS or owner who wishes to have confirmation 844, and 948). of the cause of the murmur. Diagnostic Overview • An echocardiogram should be considered RISK FACTORS First, an incidentally detected heart murmur for puppies and kittens with a murmur that • Structural heart disease is pursued through careful characterization is grade 3/6 or louder, that is diastolic or • Anemia of the murmur’s timing, grade, and point of continuous, that obscures the second (or • Youth maximal intensity. Second, these characteristics, both) heart sounds, that radiates to the Clinical Presentation combined with the patient’s signalment, may carotid region or is loudest over the left provide a strong suspicion of a likely underlying apex or right hemithorax, or that is a direct HISTORY, CHIEF COMPLAINT cause. If so and the veterinarian’s tentative diag- relative of an animal with congenital heart • By definition: identified in patients that are nosis is of a benign process, the client is satisfied disease. presented for noncardiovascular concerns, with this opinion without confirmation, and • NT-pro-BNP testing in cats can raise or lower such as annual wellness exams, noncardiac the animal is not to be used for breeding nor the likelihood of structural heart disease medical concerns, or preanesthetic evaluation. subjected to cardiovascular stress, diagnostic (notably cardiomyopathy) as the cause of • Although no historical signs are associated testing is not essential. Otherwise, diagnostic the murmur. with the murmur, misleading or overlapping testing should be pursued.

signs are common, including cough, exercise TREATMENT intolerance, and others, which can be caused Differential Diagnosis by unrelated comorbidities. Murmurs may be nonpathologic (the heart is Treatment Overview structurally normal) or pathologic (caused by Because a murmur is a physical finding alone, PHYSICAL EXAM FINDINGS a structural heart lesion): no treatment is warranted. • Heart murmur (by definition), which is • Nonpathologic (benign) murmurs are further described according to timing, grade, and described as functional if a plausible physi- Acute and Chronic Treatment point of maximal intensity (p. 414) ologic cause is detectable (e.g., anemia) or as Initiation of treatment in the absence of a • Auscultatory features of murmurs that are innocent if no cardiac or extracardiac cause diagnosis is not appropriate. It can lead to nonpathologic (see Differential Diagnosis for the murmur can be identified. administration of medications a patient does below) classically meet the six S criteria, which • Pathologic murmurs can be caused by any not need (or that are contraindicated), cause are typically systolic, soft (grade 1-2/6), sensi- cardiac disorder of any degree and do not unnecessary expense, and cause adverse treat- tive (prone to change in intensity with heart automatically indicate a severe condition. ment effects.

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ADDITIONAL SUGGESTED RELATED CLIENT EDUCATION READINGS SHEETS Boswood A, et al: Effect of pimobendan in dogs with preclinical myxomatous mitral valve disease Consent to Perform Echocardiography Disorders

and cardiomegaly: the EPIC study—a randomized Dilated Cardiomyopathy Diseases and clinical trial. J Vet Intern Med 30(6):1765-1779, Heart Failure 2016. How to Count Respirations and Monitor Chetboul V, et al: Comparative adverse cardiac effects Respiratory Effort of pimobendan and benazepril monotherapy in Mitral/Tricuspid Regurgitation Due to Myxo- dogs with mild degenerative mitral valve disease: matous Heart Valve Disease a prospective, controlled, blinded, and randomized study. J Vet Intern Med 21(4):742-753, 2007. Chetboul V, et al: Effect of benazepril on survival and cardiac events in dogs with asymptomatic mitral valve disease: a retrospective study of 141 cases. J Vet Intern Med 22:905-914, 2008. Ettinger SJ, et al: Effects of enalapril maleate on survival of dogs with naturally acquired heart failure. The Long-Term Investigation of Veterinary Enalapril (LIVE) study group. J Am Vet Med Assoc 213(11):1573-1577, 1998. Häggström J, et al: Effect of pimobendan or benazepril hydrochloride on survival times in dogs with congestive heart failure caused by naturally occurring myxomatous mitral valve disease: the QUEST study. J Vet Intern Med 22:1124-1135, 2008. Häggström J, et al: An update on treatment and prognostic indicators in canine myxomatous mitral valve disease. J Small Anim Pract 50(suppl 1):25-33, 2009. Jeunesse E, et al: Effect of spironolactone on diuresis and urine sodium and potassium excretion in healthy dogs. J Vet Cardiol 9(2):63-68, 2007. Keene BW, et al: Management of heart failure in dogs. In Bonagura JD, et al, editors: Kirk’s Current veterinary therapy XIV, St. Louis, 2009, Saunders, pp 769-780. Luis Fuentes V: Management of feline myocardial disease. In Bonagura JD, et al, editors: Kirk’s Current veterinary therapy XIV, St. Louis, 2009, Saunders, pp 809-815. MacDonald KA, et al: Effect of spironolactone on diastolic function and left ventricular mass in Maine coon cats with familial hypertrophic cardiomyopathy. J Vet Intern Med 22(2):335-341, 2008. Ouellet M, et al: Effect of pimobendan on echocardiographic values in dogs with asymptomatic mitral valve disease. J Vet Intern Med 23(2):258-263, 2009. Sisson D, et al: Management of heart failure: principles of treatment, therapeutic strategies, and pharmacology. In Fox PR, et al, editors: Textbook of canine and feline cardiology, ed 2, Philadelphia, 1999, Saunders, pp 216-250. The BENCH (BENazepril in Canine Heart disease) Study Group: Long-term tolerability of benazepril in dogs with congestive heart failure. J Vet Cardiol 6(1):7-13, 2004.

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Possible Complications PEARLS & CONSIDERATIONS the murmur’s cause (pathologic or nonpatho- Overinterpretation or underinterpretation of logic) without an echocardiogram. incidentally detected heart murmurs can lead Comments to failure to provide an accurate treatment plan • 25%-69% of cats with heart murmurs have SUGGESTED READING and prognosis. no detectable heart disease. Disorders Côté E, et al: Management of incidentally-detected Diseases and • Treatment of a heart murmur is never heart murmurs in dogs and cats. J Am Vet Med Assoc 246:1076, 2015. PROGNOSIS & OUTCOME indicated. The murmur is a clue, and the cause to which the clue is pointing may or AUTHOR: Etienne Côté, DVM, DACVIM Because incidentally detected murmurs occur may not benefit from treatment. EDITOR: Meg M. Sleeper, VMD, DACVIM in animals without associated clinical signs, the prognosis is often fair to good. Many Technician Tips disorders are progressive, but some (notably Cats routinely have heart murmurs that are patent ductus arteriosus) lend themselves to heart-rate dependent or that can vary in being cured. The exact prognosis therefore intensity between anesthesia and being awake. depends on establishing the underlying cause These characteristics are typical of physiologic and its degree of severity. murmurs, but it is impossible to be certain of

Client Education Heart Murmur, Physiologic Sheet

PHYSICAL EXAM FINDINGS BASIC INFORMATION relatively smaller left ventricular outflow • These murmurs are more easily auscultated tract without other changes consistent Definition over the left heart base, occur during systole, with SAS. Heart murmurs not associated with cardiac and are usually soft (

logic heart murmurs Etiology and Pathophysiology DIAGNOSIS Epidemiology • The genesis of a murmur is affected by Diagnostic Overview SPECIES, AGE, SEX multiple factors; structural heart disease Physiologic heart murmurs cannot be diagnosed Physiologic heart murmurs are common creates turbulence and/or increases blood solely by auscultation, and an echocardiogram in puppies and kittens, and these generally velocity due to valvular leakage (regurgita- is necessary to rule out structural heart disease. disappear by 4-6 months of age. Other causes tion), abnormal shunts, or obstructive lesions However, the echocardiogram may be delayed if for murmurs unrelated to heart disease can be (p. 414). there is evidence supporting a cause for physi- detected at any age. • Physiologic heart murmurs result from a rela- ologic murmur (e.g., if severe anemia exists, tively high cardiac output. It is hypothesized echocardiogram may be postponed to see if GENETICS, BREED PREDISPOSITION that young patients have a relatively high resolution of anemia results in resolution of • Hound dogs (e.g., greyhound, Italian grey- stroke volume for their great vessels, causing murmur). hounds, salukis) and, in general, athletic dog physiologic murmurs. As these patients grow, breeds are particularly prone to developing their great vessels enlarge and the murmur Differential Diagnosis physiologic heart murmurs. disappears, usually by 6 months of age. Other causes of heart murmurs: congenital • Boxer dogs • Changes in blood properties, such as its (pulmonic or subaortic stenosis, ventricular viscosity or density, can also lead to heart septal defects, atrioventricular valve stenosis), RISK FACTORS murmurs in normal hearts. In patients with acquired (degenerative valvular disease, sec- • Athleticism anemia, the combination of decreased blood ondary valvular regurgitation due to dilated, • Anemia viscosity due to a low hematocrit and an hypertrophic, or restrictive cardiomyopathy, • Other high cardiac output conditions increased stroke volume can result in a bacterial endocarditis). (anxiety, hyperthyroidism, fever) physiologic murmur. • Greyhounds and other athletic hunting dogs Initial Database ASSOCIATED DISORDERS may have a soft, basilar systolic murmur that • Echocardiogram Commonly associated with severe anemia is physiologic. An echocardiogram, which is • Hematocrit Clinical Presentation necessary to rule out a pathologic cause for

the murmur, may demonstrate transaortic TREATMENT HISTORY, CHIEF COMPLAINT velocities that are slightly increased but still • Physiologic murmurs in puppies/kittens in the normal range and a normal cardiac Treatment Overview or athletic dogs are found during routine structure. • No treatment is necessary for pediatric or checkups. • Although boxer dogs are predisposed to athletic murmur. • Patients with murmurs caused by anemia subaortic stenosis (SAS), these dogs also • Patients with physiologic murmurs due or fever can show clinical signs associated have an increased prevalence of physiologic to anemia or fever need treatment for the to these underlying conditions. murmurs that are thought to be due to a underlying systemic condition.

www.ExpertConsult.com 492 Hypercalcemia, Idiopathic Feline

○ ○ Assess calcium × phosphorous (Ca • PO4) Parathyroid glands should be ≈1.3-3.3 mm • Plicamycin product: if > 60, nephron damage is a in greatest width (dogs and cats). • Cinacalcet concern. In PHPTH, typically < 45. ○ In dogs with PHPTH, a mass is typically • Urinalysis identified involving one or more parathy- Chronic Treatment ○ Uroliths and calcium-containing crystal- roid gland(s), usually 4-8 mm in greatest Treat inciting cause luria are common. diameter. ○ All causes of hypercalcemia lead to poorly ○ Dogs with renal secondary hyperparathy- Possible Complications concentrated urine (by nephrogenic roidism have enlargement of two, three, Overcorrection (hypocalcemia), urolithiasis, diabetes insipidus). or all four parathyroid glands. nephron damage (if Ca • PO4 > 60) ○ Persistent isosthenuria (1.008-1.012) • Additional testing based on abnormalities with concurrent azotemia suggests kidney identified (e.g., fine-needle aspiration of Recommended Monitoring disease or hypoadrenocorticism. enlarged lymph nodes, fungal serology) • Serum total and ionized calcium ○ Hyposthenuria, isosthenuria, or minimally concentrations

concentrated urine associated with PHPTH TREATMENT • Renal parameters (mean ≈1.011), with values as low as 1.002. • Serum electrolytes • Thoracic radiographs Treatment Overview ○

Nodular lung patterns or lymphadeno- Successful treatment of underlying cause lowers PROGNOSIS & OUTCOME megaly suggest neoplasia or fungal disease. serum calcium. If (Ca • PO4) is > 60, additional ○ Cranial mediastinal mass common in measures may be required. Rapid reduction in • Varies; depends on ability to achieve nor- dogs that have hypercalcemia secondary serum calcium, even with extremely increased mocalcemia and correct underlying cause to lymphoma. values (15-23 mg/dL) is not necessary if (Ca • • Excellent for PHPTH ○ Lytic bone lesion suggests multiple PO4) is < 60, which is typical of PHPTH. Even

myeloma or other metastatic cancer. when calcium is within reference range, if Ca • PEARLS & CONSIDERATIONS • Abdominal imaging (ultrasound ± radiographs) PO4 is increased, nephron damage may ensue. ○ Lesions suggesting malignancy (lymph- Comments adenopathy, hepatosplenomegaly, possible Acute General Treatment • Remember, renal failure is not caused by metastases, including lytic bone lesions) Primary (most efficacious): hypercalcemia alone. ○ Uroliths (calcium phosphate, calcium • IV fluid therapy (calcium free; avoid lactated • Correcting total calcium concentration for oxalate, or both) and bladder wall thicken- Ringer’s solution) hypoalbuminemia or hyperalbuminemia is ing: common in PHPTH ○ Dilution of serum calcium and phosphorus not reliable (instead, measure serum ionized ○ Assess renal structure. Renal dystrophic concentrations, improved glomerular calcium concentrations directly). mineralization rarely is apparent radio- filtration rate • Oral consumption of calcium alone does graphically or ultrasonographically. ○ Twice maintenance plus dehydration not cause hypercalcemia. deficit should be administered over the • Hypercalcemic dogs that are ill are not likely Advanced or Confirmatory Testing first 24 hours, assuming no heart disease, to have PHPTH. • Ionized calcium (i.e., biologically active oliguria, or other factor predisposing to component of the total serum calcium): intolerance of volume load; adjust accord- Technician Tips normal or low with CKD, increased with ing to clinical signs. • Urolithiasis related to hypercalcemia can most other causes of hypercalcemia (e.g., • Furosemide 2-3 mg/kg IV q 4-8h. Calciuric cause urinary obstruction. Straining to PHPTH, hypercalcemia of malignancy, diuretic (unlike thiazide diuretics or spirono- urinate is an emergent condition. vitamin D toxicosis) lactone) is not recommended for pets with • Hypercalcemic dogs should always have • Serum PTH and PTHrP concentrations renal insufficiency. drinking water available and should be given during hypercalcemia • Glucocorticoids (prednisone or dexametha- ample opportunity to urinate. ○ PTH should be undetectable in response sone): decrease intestinal calcium absorption, to hypercalcemia. increase renal calcium excretion. Diagnostic SUGGESTED READING ○ PTH values within or above reference samples (e.g., lymph node aspirate, bone Skelly BJ: Primary hyperparathyroidism. In Ettinger range are consistent with PHPTH. marrow aspirate, liver biopsy) should be SE, et al, editors: The textbook of veterinary ○ Undetectable PTH and detectable PTHrP obtained before treatment because steroids internal medicine, ed 8, St. Louis, 2017, Elsevier, concentrations are consistent with hyper- may mask lymphoma. pp 1715-1727. calcemia of malignancy. Secondary therapies (more expensive and not AUTHOR: Edward C. Feldman, DVM, DACVIM • Serum vitamin D concentrations: if suspect often required): EDITOR: Leah A. Cohn, DVM, PhD, DACVIM intoxication (p. 164) • Bisphosphonates • Cervical ultrasound • Calcitonin

Hypercalcemia, Idiopathic Feline

Epidemiology RISK FACTORS BASIC INFORMATION SPECIES, AGE, SEX Genetics, diet, or the use of urinary acidifiers Definition Cats of any age (often 5-10 years) and either sex This poorly understood condition is the most ASSOCIATED DISORDERS common cause of increased ionized calcium GENETICS, BREED PREDISPOSITION Calcium oxalate urolithiasis, chronic kidney (iCa) in cats. Long-haired cats appear to be overrepresented. disease (CKD)

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Clinical Presentation • Total thyroxine (T4): unremarkable • Alendronate may cause esophageal stricture HISTORY, CHIEF COMPLAINT • Thoracic and abdominal imaging: rule out or irritation of mucous membranes. • Usually an incidental finding (e.g., geriatric neoplasia • In humans, alendronate may cause osteone- screening) or associated with vague clinical crosis of the mandible and maxilla; if dental signs such as weight loss, diarrhea, constipa- Advanced or Confirmatory Testing work is required, it should be completed Disorders Diseases and tion, vomiting, or anorexia Serum parathyroid hormone (PTH), parathy- before starting alendronate. • The modest degree of hypercalcemia typical roid hormone–related protein (PTHrP), vitamin of the disorder is seldom associated with D profile: Recommended Monitoring the most worrisome adverse effects of • PTH: below or near the lower end of the Recheck iCa 6 weeks after starting diet trial or hypercalcemia (e.g., tissue mineralization). reference range 1-2 weeks after any change in medical therapy. • Sometimes, signs related to calcium oxalate • PTHrP: typically below limits of detection Once controlled, iCa should be rechecked q urolithiasis (e.g., dysuria, periuria [p. 1014]) • Vitamin D: 25(OH)D3 and 1,25(OH)2D3 4-6 months. Serum chemistry profile (azotemia) or concurrent CKD (e.g., polyuria/ polydip- within reference range and urinalysis (crystalluria) should be checked sia [pp. 167 and 169]) are noted. q 6-12 months.

PHYSICAL EXAM FINDINGS TREATMENT PROGNOSIS & OUTCOME No specific physical exam findings. Calcium Treatment Overview oxalate urolithiasis can cause signs of urethral Because the degree of hypercalcemia is typically With treatment, excellent. Without treatment, obstruction in some affected cats. modest, emergent efforts to reduce calcium are urolithiasis remains a concern. not required. After other causes of hypercalcemia Etiology and Pathophysiology have been ruled out, dietary therapy is typically PEARLS & CONSIDERATIONS • Extracellular total calcium fractions include begun. If unsuccessful, medical management biologically active iCa (≈52%), protein- is attempted. Concurrent urolithiasis and/or Comments bound calcium (≈40%), and calcium com- CKD must be addressed, if present. • Other causes of hypercalcemia may be associ- plexed to other molecules (≈8%). Calcium ated with life-threatening disease and should balance is closely controlled in health through Acute General Treatment be ruled out before instituting treatment for intestinal absorption, renal excretion, and Rarely, calcium oxalate urolithiasis results in idiopathic hypercalcemia. redistribution from bone. urethral obstruction, requiring emergency • Severe hypercalcemia is seldom caused by • As the name implies, the cause of ionized intervention (p. 1009) idiopathic hypercalcemia. hypercalcemia in affected cats remains • Renal damage associated with hypercalcemia unknown. Chronic Treatment is related to the calcium × phosphorus • Many cats can be managed with dietary product more than to the iCa. Because

DIAGNOSIS therapy alone. hypercalcemia is mild and phosphorus is • If ionized hypercalcemia persists after a within reference range, kidney damage is Diagnostic Overview 6-week diet trial, medical therapy with unlikely with idiopathic hypercalcemia alone. Typically, total calcium is measured first, glucocorticoids or bisphosphonate drugs is • It is possible for a cat to have both CKD and and if above the upper end of the reference recommended. idiopathic hypercalcemia, which can confuse range, iCa is measured. If that too is above the ○ Prednisolone (not prednisone) 0.5-1 mg/ the diagnosis (e.g., CKD can cause increased reference range, attempts should be made to kg PO q 12-24h. Avoid use until diag- total calcium but normal iCa). identify a cause of hypercalcemia. Idiopathic nostic testing is complete. • Use of formulas to adjust calcium concentra- hypercalcemia is a diagnosis of exclusion. ○ Alendronate 5-20 mg/CAT PO q 7 days. tion based on albumin is not appropriate Begin with lower dose, and titrate up as for cats with hypercalcemia. Instead, ionized Differential Diagnosis needed. Administer after a 12-hour fast. calcium concentrations should be measured Hypercalcemia (pp. 491 and 1232) Pills should not be cut because they can be directly. highly irritating to the oral and esophageal Initial Database surfaces. Follow pill with 5-10 mL of Technician Tips • Serum biochemistry profile: increased total water to reduce risk of esophageal stricture. Demonstrate for owners how to properly calcium; phosphorus within reference range Liquid formulations are available but may administer medications, including giving water ○ Concurrent CKD associated with azote- not be palatable. afterward to minimize the risk of esophageal mia, hyperphosphatemia ○ Occasionally, a combination of predniso- stricture with alendronate. • Ionized calcium: usually mild to moderate lone and alendronate is required to control increase (80% between 1.5 and 1.75 mmol/L; iCa. Client Education 1.4 mmol/L is the upper end of the reference Proper administration of medications range) Nutrition/Diet ○ If iCa cannot be measured quickly • High-fiber diet and/or psyllium supplementa- SUGGESTED READING in house, sample should be collected tion recommended Finch NC: Hypercalcemia in cats: the complexities of anaerobically and transported on ice. • Wet/canned foods preferred calcium regulation and associated clinical challenges. ○ Exposure of sample to air can lead to loss • Oxalate prevention diets useful for cats with J Feline Med Surg 18:387-399. 2016. of CO2, resulting in decreased iCa. no evidence of CKD AUTHOR: Leah A. Cohn, DVM, PhD, DACVIM ○ Lactic acid accumulation alters the pH • Renal diets are appropriate for cats with EDITOR: Etienne Côté, DVM, DACVIM of stored samples, resulting in increased concurrent azotemia. iCa. • CBC: unremarkable Possible Complications • Urinalysis: variable urine specific gravity, • Uncontrolled hypercalcemia may result in possible calcium oxalate crystalluria calcium oxalate urolithiasis.

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ADDITIONAL SUGGESTED READINGS Hardy BT, et al: Treatment of ionized hypercalcemia in 12 cats (2006–2008) using PO-administered Disorders

alendronate. J Vet Intern Med 29:200-206, 2015. Diseases and Midkiff AM, et al: Idiopathic hypercalcemia in cats. J Vet Intern Med. 14:619-626, 2000. Savary KG, et al: Hypercalcemia in cats: a retrospective study of 71 cases (1991–1997). J Vet Intern Med 14:184-189, 2000. Schenck PA, et al: Prediction of serum ionized calcium concentration by serum total calcium measurement in cats. Can J Vet Res 74:209-213, 2010.

www.ExpertConsult.com 498 Hypernatremia

Nutrition/Diet Recommended Monitoring • Hypercholesterolemia may indicate the pres- • Hypertriglyceridemia • Monitor plasma TGs 4-8 weeks after initia- ence of an underlying disorder but rarely ○ Dietary fat restriction (dog: < 20% tion of low-fat diet, then every 6-12 months. causes clinical disease. metabolizable energy [ME]; cat: < 25% • Monitor hematologic/biochemical parameters ME) with fibrates, niacin, or lovastatin. Prevention ○ If a low-fat diet is unsuccessful, a • Treat predisposing disorders.

nutritionist can design an ultralow-fat PROGNOSIS & OUTCOME • Monitor TG concentrations in susceptible (10%-12% ME) diet. breeds. • Hypercholesterolemia • Successful management depends on adequate ○ Low-fat diet with increased amounts of control of underlying disease(s) and reduction Technician Tips soluble fiber of plasma lipid concentrations. • Alert the attending veterinarian if the • Cats with peripheral neuropathies generally supernatant in a hematocrit tube or serum Drug Interactions have clinical signs resolve within 4-12 weeks or plasma in a centrifuged tube is cloudy • Statins should not be used concurrently with of instituting diet change. and the patient has not eaten in > 12 hours. azole antifungals, cyclosporine, diltiazem, or • Lipemia can increase total solids measured by

gemfibrozil. PEARLS & CONSIDERATIONS refractometry and can interfere with multiple • Statins may increase the toxicity of digoxin. biochemical tests. Comments Possible Complications • Hyperlipidemia in patients fasted > 12 hours SUGGESTED READING • Fibrates may cause myalgia and hepatopathy. is abnormal. Xenoulis PG, et al: Canine hyperlipidaemia. J Small • Niacin may cause hyperglycemia, erythema, • Lipemic plasma is an indication of hypertri- Anim Pract 56:595-605, 2015. pruritus, myalgia, and hepatopathy. glyceridemia, not hypercholesterolemia. AUTHOR: Karen M. Tefft, DVM, MVSc, DACVIM • Statins may cause lethargy, diarrhea, myalgia, • Hypertriglyceridemia often signals underlying EDITOR: Ellen N. Behrend, VMD, PhD, DACVIM and hepatopathy. disease and may cause clinical disease.

Hypernatremia

BASIC INFORMATION hypernatremia; volume status provides clues • Acute hyperosmolality can cause brain cells about the cause to shrink because intracellular water is pulled Definition into the extracellular fluid space, resulting in A serum sodium (Na+) concentration above HISTORY, CHIEF COMPLAINT rupture of vessels and intracranial bleeding. the reference range; caused by net water loss • Clinical signs (e.g., vomiting, diarrhea, • If hypernatremia comes about more slowly, (most common) or Na+ gain polyuria/polydipsia [PU/PD]) often related the brain can adapt through production of Epidemiology to the underlying cause of hypernatremia idiogenic osmoles, which hold water volume • Severity and rapidity of onset correlate in the brain cells. SPECIES, AGE, SEX with severity of signs attributed directly to ○ Overly rapid correction of long-standing No species, age, or sex predisposition hypernatremia, which can include hypernatremia causes water to be pulled ○ Mental dullness/ inappropriate mentation into the brain cells by idiogenic osmoles, GENETICS, BREED PREDISPOSITION ○ Ataxia resulting in brain swelling and neurologic Essential adipsic hypernatremia rarely reported ○ Stupor/coma damage. in schnauzers, other dog breeds, and cats; may ○ Seizures • Causes of hypernatremia (p. 1237) have a genetic basis ○ Muscle weakness ○ Pure water deficit: normovolemic hypernatremia (e.g., water deprivation [especially RISK FACTORS PHYSICAL EXAM FINDINGS with diabetes insipidus], adipsia) • Diuresis in the absence of adequate available • Findings often relate to the underlying cause ○ Hypotonic fluid loss (most common): water replacement of hypernatremia. hypovolemic hypernatremia (e.g., dia- • Excessive water loss from nonrenal sources • When Na+ > 170 mEq/L, findings directly betes mellitus, postobstructive diuresis, (e.g., vomiting, diarrhea, burns) attributed to hypernatremia can become gastrointestinal (GI) fluid loss, burns, • Acute administration/consumption of large apparent (see Chief Complaint). chronic kidney disease) amounts of Na+ (e.g., sea water consumption) • Evidence of volume depletion or excess ○ Increased Na+ retention or intake: hyper- ○ Hydration usually adequate (from movement volemic hypernatremia (e.g., hypertonic ASSOCIATED DISORDERS of water from intracellular space to extracel- enema solutions, sea water consumption, Essential adipsic hypernatremia, diabetes lular space) until extreme water loss occurs excess hypertonic saline infusion) insipidus, central nervous system (CNS) ○ Volume depletion: loss of skin turgor, weak

damage pulse, tachycardia, delayed capillary refill DIAGNOSIS Clinical Presentation time ○ Volume excess: serous nasal discharge, Diagnostic Overview DISEASE FORMS/SUBTYPES tachypnea, harsh lung sounds Hypernatremia may be suspected in depressed • Can be acute or chronic; accumulation of animals with conditions known to predispose idiogenic osmols in chronic hypernatremia Etiology and Pathophysiology to hypernatremia, or it can be an incidental impact treatment • Na+ and its anions account for ≈95% of finding on serum biochemical profile. Signs of • Categorized by volume status as hypovo- osmotic activity in extracellular fluids; there- hypernatremia may not be apparent until Na+ lemic, normovolemic, or hypervolemic fore, hypernatremia causes hyperosmolality. > 175-180 mEq/L.

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ADDITIONAL SUGGESTED RELATED CLIENT EDUCATION READINGS SHEETS Blackstock KJ, et al: Transient hyperlipidemia in a litter of kittens. J Vet Emerg Crit Care 22:703-709, Consent to Perform Abdominal Ultrasound Disorders

2012. How to Change a Pet’s Diet Diseases and Fletcher JM: Diagnosis and management of hyperlipidemia. In Proceedings from the 14th annual Southwest Veterinary Symposium, 2016, Fort Worth, TX. Hill RC: Dietary and medical considerations in hyperlipidemia. In Ettinger SJ, et al, editors: Textbook of veterinary internal medicine, ed 8, Philadelphia, 2017, Saunders, pp 758-764. Kluger EK, et al: Assessment of the Accutrend GCT and PTS CardioChek meters to measure blood triglyceride concentrations in cats. J Feline Med Surg 12:458-465, 2010. Kluger EK, et al: Evaluation of two portable meters for determination of blood triglyceride concentration in dogs. Am J Vet Res 71:203-210, 2010. Kluger EK, et al: Serum triglyceride concentration in dogs with epilepsy treated with phenobarbital or with phenobarbital and bromide. J Am Vet Med Assoc 233:1270-1277, 2008. Kluger EK, et al: Triglyceride response following an oral fat tolerance test in Burmese cats, other pedigree cats and domestic crossbred cats. J Feline Med Surg 11:82-90, 2009. Kutsunai M, et al: The association between gall bladders mucoceles and hyperlipidaemia in dogs: a retrospective case control study. Vet J 199:76-79, 2014. Mori N, et al: Predisposition for primary hyperlipidemia in miniature schnauzers and Shetland sheepdogs as compared to other canine breeds. Res Vet Sci 88:394-399, 2010. Watson P, et al: Hypercholesterolaemia in Briards in the United Kingdom. Res Vet Sci 54:80-85, 1993. Xenoulis PG, et al: Association between serum triglyceride and canine pancreatic lipase immunoreactivity concentrations in miniature schnauzers. J Am Anim Hosp Assoc 46:229-234, 2010. Xenoulis PG, et al: Association of hypertriglyceridemia with insulin resistance in healthy miniature schnauzers. J Am Vet Med Assoc 238:1011-1016, 2011. Xenoulis PG, et al: Serum liver enzyme activities in healthy miniature schnauzers with and without hypertriglyceridemia. J Am Vet Med Assoc 232:63- 71, 2008. Zarfoss MK, et al: Solid intraocular xanthogranuloma in three miniature schnauzer dogs. Vet Ophthalmol 10:304-307, 2007.

www.ExpertConsult.com Hyperparathyroidism, Primary 499

Differential Diagnosis TREATMENT PROGNOSIS & OUTCOME • Encephalopathic signs: hypoglycemia, hypo- natremia, hepatic encephalopathy, uremia, Treatment Overview • Prognosis depends on underlying cause intoxications, hypoxia, CNS disorders Acute hypernatremia (<24-hour duration) can as well as appropriate treatment. Often, • Hypernatremia: pseudohypernatremia occurs be corrected rapidly, but longer-standing hyper- hypernatremia is completely reversible if Disorders Diseases and occasionally in hyperproteinemic or hyperlip- natremia must be corrected slowly (often over treated appropriately in a timely manner. idemic animals. Confirm true hypernatremia 48-72 hours at < 8-12 mEq/L per 24 hours). • Guarded to grave after coma occurs with direct selective electrode measure. Because frequent measures of serum Na+ are

required, animals with severe hypernatremia PEARLS & CONSIDERATIONS Initial Database should be treated at 24-hour care facilities • Review history for water consumption/thirst, capable of monitoring electrolytes in real time. Comments urine production, possible salt ingestion/ • Hypernatremia is more often the result of administration Acute General Treatment water loss rather than Na+ gain. • Serum biochemical profile • See Hypernatremia Algorithm (p. 1428). • For slow-onset hypernatremia, correct slowly; ○ Na+ above upper reference range (by • For hypernatremia of short duration (<24 for rapid onset of hypernatremia, correct definition; usually Na+ > 157 mEq/L) hours), rapid correction is appropriate rapidly. ○ Hyperchloremia (common) (1.5-2 mEq/L/h) using no or low Na+ fluids • Hyperaldosteronism is rare and causes ○ Azotemia (may accompany hypovolemia (e.g., 5% dextrose, 0.45% sodium chloride, hypertension more often than hypernatre- or kidney disease) one-half strength lactated Ringer’s solution) mia (excess Na+ pulls fluid into vascular ○ Hyperphosphatemia (may accompany • For hypernatremia lasting for > 24 hours, space). kidney disease or sodium phosphate enema correct no more quickly than 0.5 mEq/L/h use) (12 mEq/L/day). This rate may be difficult Prevention ○ Increased albumin in hemoconcentrated to achieve with very-low-sodium fluids; • Provide ample access to water for any animal state keep in mind that even fluids with a Na+ with polyuria or salt access. ○ Serum osmolality (measured or calculated); concentration of 40 mEq/L (e.g., Normosol • Do not allow dogs to drink sea water. always increased M, Plasma-Lyte 56) can provide necessary • Mix generous amounts of water in moist • CBC: may show evidence of hemoconcentra- water with a lower Na+ content than the food for animals with adipsia. tion patient’s serum. Frequent (i.e., q 2-4h) • Urinalysis, with urine osmolality (if available): rechecks of Na+ are essential. Technician Tips hyposthenuria (e.g., diabetes insipidus), • For animals that are not vomiting and Any animal with polyuria should be provided isosthenuria (e.g., kidney disease), or mentally appropriate, enteral water supple- access to water at all times (or IV fluids if GI/ concentrated urine (e.g., salt intoxication, mentation is useful. oral intake is not allowed) during any hospital GI losses) stay, even if brief. Chronic Treatment Advanced Diagnostic Testing Address underlying cause of hypernatremia. Client Education Additional testing is aimed at identification of Stress the importance of free-choice water for the underlying cause of hypernatremia; choice Possible Complications polydipsic pets. of test depends on suspected cause. Common Coma, seizures, and death tests: SUGGESTED READING • Abdominal imaging: cause of vomiting or Recommended Monitoring Guillaumin J, et al. Disorders of sodium and water diarrhea, evaluation of kidneys and adrenal • During correction of chronic, severe hyper- homeostasis. Vet Clin North Am Small Anim Pract glands natremia, monitor serum Na+ q 2-4h to be 47:293-312, 2017. • Brain imaging by MRI or CT: if hypotha- sure correction is not overly rapid. AUTHOR: Michael Schaer, DVM, DACVIM, DACVECC lamic lesion suspected • Repeat neurologic evaluations at least EDITOR: Leah A. Cohn, DVM, PhD, DACVIM • Tests to confirm endocrinopathies, if indicated: daily; signs of overly rapid correction may diabetes insipidus (p. 250), hyperaldoster- not be apparent for 48 hours or more after onism, diabetes mellitus (p. 251) treatment.

Client Education Hyperparathyroidism, Primary Sheet

GENETICS, BREED PREDISPOSITION BASIC INFORMATION • Lower urinary tract signs (caused by infec- • Any breed tion or cystic calculi), including pollakiuria, Definition • Keeshond: inherited (autosomal dominant); stranguria, and hematuria (≈50% of dogs) Primary hyperparathyroidism (PHPTH) is a genetic test is available (http://ahdc.vet • Weakness, lethargy (≈40%-50% of dogs caused by increased synthesis and secretion of .cornell.edu/docs/PHPTInstructions.pdf). and cats) parathyroid hormone (PTH) by autonomously • Hereditary neonatal PHPTH has been • Inappetence (≈25%-30% of dogs; ≈40% functioning parathyroid cells. reported in two German shepherd of cats), vomiting (≈10% of dogs; ≈40% dogs. of cats) Epidemiology ≈ Clinical Presentation • Some ( 30% dogs) have no clinical signs; SPECIES, AGE, SEX hypercalcemia is an incidental finding. • Dogs: uncommon; older dogs predominantly; HISTORY, CHIEF COMPLAINT no sex predisposition • Polyuria/polydipsia (≈50% dogs; ≈10% PHYSICAL EXAM FINDINGS • Cats: rare; older cats typically affected cats) • Physical exam: typically unremarkable