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698 Nystagmus

• Excess circulating phosphorus also inhibits TREATMENT PROGNOSIS & OUTCOME
calcitriol synthesis and can lower iCa by the Treatment Overview • Depends on presence and location of
VetBooks.ir DIAGNOSIS Goals of treatment are to increase intestinal pathologic fractures, which worsen the
mass law effect.
prognosis because of pain and a potentially
absorption of calcium and vitamin D and
long convalescent period
Diagnostic Overview decrease PTH production. • Incidentally discovered NSHP that is due
The diagnosis is strongly suspected in young Acute General Treatment to inappropriate diet typically carries a good
animals with a history of an inadequate diet, • Feed a properly formulated, complete, and prognosis.
radiographic evidence of diffuse bone loss, and balanced diet. • For animals with malabsorption, the prog-
pathologic fractures. • Stop use of all supplements. nosis depends on the underlying cause and
• Supportive therapy for pain or fractures (cage effectiveness of therapy.
Differential Diagnosis rest or limited activity as indicated)
• Other causes of lameness, bone pain, loss • Treatment of malabsorption when present PEARLS & CONSIDERATIONS
of bone density, or fractures, including • Dietary supplementation with oral calcium
congenital problems in young animals 25-50 mg/kg elemental Ca (e.g., 62.5- Comments
• Renal secondary hyperparathyroidism (p. 125 mg/kg calcium carbonate) daily if • Animals fed homemade diets should be
878) (ruled out based on serum biochemistry clinical signs of hypocalcemia (p. 515) are monitored as part of a routine nutritional
profile and urinalysis) present, discontinuing when signs resolve assessment.
• Hyperadrenocorticism-associated secondary • Review balanced homemade diet recipes
hyperparathyroidism in older dogs (ruled Chronic Treatment with owners at every visit to ensure that
out based on adrenal function testing and • Ensure that a properly formulated diet is substitutions or omissions have not occurred.
clinical signs) fed.
• Genetic defects in calcitriol production or • If a homemade diet is fed, ensure use of an Prevention
use (vitamin D–dependent rickets type 1 or appropriate and balanced recipe for long- Clinicians should inform owners to
2); clinical signs are the same in the absence term use. • Feed their pets nutritionally complete and
of compatible diet history or malabsorptive • Supplemental oral calcium may be indicated balanced pet foods rather than improperly
disorder. in cases of chronic malabsorption but are formulated homemade diets.
not necessary if the diet is inadequate and • Avoid supplementing balanced diets with
Initial Database subsequently corrected. meats, vitamins, or minerals.
• CBC and serum biochemical profile: serum
total calcium concentration normal to low. Nutrition/Diet Technician Tips
NOTE: Serum phosphorus and alkaline Feed a properly formulated commercial Be careful when handling or walking affected
phosphatase may be elevated in normal or homemade diet appropriate for the life animals because fractures can easily occur. Cage
animals relative to the laboratory reference stage. rest during healing is critical for recovery.
range, especially in those that are young and
growing. Possible Complications Client Education
• Radiography of the skull, axial skeleton, • Clinicians should repeat tests of PTH, iCa, • Clinicians should explain the risks of serious
and limbs: diffusely decreased cortical bone and 25-OH-D concentrations 3-4 weeks skeletal problems associated with nutrient
density; fractures possible after initiating treatment. PTH should be imbalance to clients feeding homemade diets,
• Diet history decreased and 25-OH-D increased compared especially to young, growing animals.
with pretreatment values. Clinicians should • Clinicians should have the adequacy of
Advanced or Confirmatory Testing monitor the animals monthly until levels are homemade diets verified by a veterinary
• Measure serum PTH (increased), iCa (low normal. nutritionist.
to normal), and 25-hydroxyvitamin D • Clinicians should measure PTH, iCa, and
(25-OH-D; typically low) concentrations 25-OH-D concentrations every 3-4 months, SUGGESTED READING
to confirm the diagnosis. even if secondary hyperparathyroidism has Cook SD, et al: A quantitative histologic study
• Serum calcitriol determination (usually resolved, especially when intestinal malab- of osteoporosis produced by nutritional second-
increased) sorption is present. ary hyperparathyroidism in dogs. Clin Orthop
• Vitamin/mineral analysis of homemade diets • Clinicians should order repeat radiography 175:105-120, 1983.
may be useful, but diet history is usually tests to assess bone density and fracture AUTHOR: Patricia A. Schenck, DVM, PhD
sufficient to help confirm suspected diagnosis. healing. EDITOR: Jennifer Larsen, DVM, PhD, DACVN

Nystagmus Client Education
Sheet

Epidemiology
BASIC INFORMATION • Jerk nystagmus with a fast and slow phase is
most common. SPECIES, AGE, SEX
Definition • Nystagmus direction is named after the Any age, breed, or sex
• Involuntary rhythmic movement of the globe direction of the fast phase.
of the eye; nystagmus occurs in a horizontal, • Pendular nystagmus is characterized by eye GENETICS, BREED PREDISPOSITION
rotary, or vertical direction. movements of equal speed without a fast or • Cats: pendular nystagmus occurs in
slow phase. otherwise normal Siamese and Himalayan

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