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764 Patent Ductus Arteriosus

rupture is frequently the chief source of the Chronic Treatment PEARLS & CONSIDERATIONS
lameness being treated. • Same as in acute cases but may require long- Comments
VetBooks.ir Acute General Treatment • Disease-modifying agents • Severity of lameness may not correlate with
term medical management for the treatment
of osteoarthritis
grade of patellar luxation. Animals with grade
Medical management:
• Nonsteroidal
antiinflammatory
(NSAIDs) in dogs drugs ○ Polysulfated glycosaminoglycan 4-5 mg/ 2 luxation are often the most painful because
kg IM once to twice weekly for 4-6 weeks
their patellae are repeatedly grinding across
○ Carprofen 2 mg/kg PO q 12h, or ○ Pentosan polysulfate 3 mg/kg SQ once the trochlear ridges. Animals with higher-
○ Deracoxib 1-2 mg/kg PO q 24h, or weekly; 10 mg/kg PO or SQ weekly up grade luxations are not painful but are instead
○ Meloxicam 0.1 mg/kg PO q 24h, or to 4 weeks impeded by joint misalignment.
○ Grapiprant 2 mg/kg PO q 24h ○ Oral formulations (glucosamine, chondroi- • Patellar luxation is usually a developmental
Physical rehabilitation for mild patellar luxa- tin sulfate, avocado soy unsaponifiables): condition, and the grade of luxation may
tions (grade 1 ± grade 2): according to labeled instructions increase as the animal matures.
• Exercises to strengthen quadriceps muscle • In bilateral luxations, the grade of patellar
function Nutrition/Diet instability may differ between stifles.
Surgical management: Weight control (p. 1077) • Soft-tissue stabilization techniques alone are
• Soft-tissue reconstruction not sufficient to stabilize moderate or severe
○ Imbrication of loose and release of tight Possible Complications luxations.
pericapsular tissues based on direction of Medical management: • Block or wedge trochleoplasty is the preferred
luxation; release of the rectus femoris or • Gastrointestinal, hepatic, renal, or other method to deepen the femoral trochlear
sartorius muscle for MPL systemic reactions to NSAIDs groove because it preserves the articular
○ Derotational suture from fabella to patella • Continued progression of degenerative joint cartilage.
or tibial tuberosity disease • In older animals with chronic patellar
• Trochleoplasty to deepen the femoral • Failure of medical management to control instability and acutely worsening lameness,
trochlear groove pain concomitant cranial cruciate ligament
○ Trochlear chondroplasty in immature dogs Surgical management: rupture is likely.
○ Abrasion trochleoplasty • Patellar reluxation (occurs in 10%-30% of
○ Block or wedge recession trochleoplasty cases, especially in dogs when tibial tuberosity Prevention
• Tibial tuberosity transposition opposite transposition has not been done) Screening and control of breeding animals for
to direction of luxation (very common in • Implant failure/tibial tuberosity avulsion prevention of patellar luxation
dogs, sometimes omitted in cats because it
is associated with a higher complication rate) Recommended Monitoring Technician Tips
• Femoral or tibial corrective osteotomies: • Laboratory monitoring of animals on NSAID To take straight craniocaudal views of the femur,
usually performed when angular deformity therapy image only one limb at a time. Hold the dog
is severe (>15° varus for the distal femur in • Weight, exercise levels, and clinical signs as in a sitting position, or angle the beam so that
MPL) dictated by the patient’s condition it is perpendicular to the femur. Do not allow
• Stifle arthrodesis may be performed as • Postoperative rehabilitation enhances clinical the stifle to splay laterally.
a salvage procedure for severe luxations recovery.
not amenable to other treatments (more SUGGESTED READING
functional in small dogs than large ones). PROGNOSIS & OUTCOME Kowaleski MP, et al: Stifle joint. In Johnston SA,
• Concurrent cranial cruciate ligament rupture et al, editors: Veterinary surgery small animal, St.
should be treated along with the MPL; • Generally good to excellent for return to Louis, 2018, Elsevier, pp 1141-1159.
osteotomy techniques such as tibial plateau normal limb function if appropriate tech- AUTHOR & EDITOR: Kathleen Linn, DVM, MS, DACVS
leveling osteotomy (TPLO) or tibial tuberos- niques are used
ity advancement (TTA) can be modified so • Degenerative joint disease progresses (radio-
that the tibial osteotomy also transposes the graphically, not necessarily symptomatically)
tibial tuberosity. despite treatment.

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BASIC INFORMATION Synonym dog breeds such as Maltese, Pomeranians,
PDA Yorkshire terriers, Shetland sheepdogs, and
Definition toy and miniature poodles
An arterial shunt between the aorta and pulmo- Epidemiology
nary artery is normally present in fetuses but SPECIES, AGE, SEX RISK FACTORS
should constrict and close within 24 hours after • All species, but much less common in cats In-breeding
birth. Patency (incomplete closure) results in a • Recognized most frequently in young animals
channel, the diameter of which determines the • Moderate predominance in females GEOGRAPHY AND SEASONALITY
amount and direction of blood flow through Breed predispositions may vary due to regional
the shunt and the impact on the patient. It is GENETICS, BREED PREDISPOSITION differences in the gene pool.
the most common congenital heart defect in Sporadic or hereditable defect occurring most
dogs, occurring in 1 of 1000. frequently in small, relatively nonmuscular

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