Page 1400 - Cote clinical veterinary advisor dogs and cats 4th

708 Open-Mouth Jaw Locking

As cats are much more sensitive, as little as Advanced or Confirmatory Testing Recommended Monitoring
5 g/kg body weight poses a risk. Co-oximetry (measures percentage of methe- CBC/hematocrit/blood smear; renal function;
VetBooks.ir DIAGNOSIS are not typically available in the limited time PROGNOSIS & OUTCOME
urinalysis
moglobin) and methemoglobin assays exist but
frame of an intoxication.
Diagnostic Overview
Diagnosis is based on historical evidence of TREATMENT • Generally good with prompt veterinary care
Allium species ingestion and the delayed onset of patients showing overt clinical signs
(usually 2-5 days) of compatible signs (anemia, Treatment Overview • Guarded with severe anemia or secondary
pale mucous membrane color, hemoglobinuria, If no clinical signs are present and recent renal damage
hemolysis). ingestion (less than 4 hours) of significant
amounts (>5 g/kg in cats, > 10 g/kg in dogs) PEARLS & CONSIDERATIONS
Differential Diagnosis of onion is confirmed, treatment can include
Toxicologic: induction of vomiting and administration of Comments
• Oxidative damage, hemolysis, anemia, or activated charcoal (if emesis unsuccessful). If • Many commercial garlic or onion powder
methemoglobinemia: acetaminophen, brown the patient is showing overt signs compatible products list the conversion for a clove of
recluse spider, chlorates, hydroxyurea, local with toxicosis, care is supportive. garlic (e.g., tsp of garlic powder equals
1
4
anesthetics, methylene blue, naphthalene one clove of garlic, or 1 Tbsp onion powder
mothballs, phenazopyridine, phenols, Acute General Treatment equals 2 cup chopped onion).
1
propylene glycol, zinc No clinical signs apparent: • One pearl onion weighs about 14 g, a small
Spontaneous, nontoxicologic: • Minimal exposure requires no treatment. onion (2 inches [5 cm] in diameter) weighs
• Anemia, hemolytic • For substantial, recent consumption 56-85 g, a medium onion (3 inches [7.5 cm]
• Anemia, immune-mediated hemolytic (>5 g/kg for cats or > 10 g/kg for dogs), in diameter) weighs 226-255 g, and a large
(p. 1197) decontamination is beneficial. onion (4 inches [10 cm] in diameter) weighs
• Anemia, blood loss (p. 57) ○ Induction of vomiting (p. 1188) 425-450 g.
○ Activated charcoal 1-2 g/kg PO (dose • A medium onion yields about 1 cup of
Initial Database according to packaging label of product; p. coarsely chopped onion.
• CBC: hematologic changes (e.g., hemolysis, 1087); especially useful if emesis unsuccessful
Heinz body anemia, methemoglobinemia) Patient showing clinical signs: Prevention
may occur as early as 12 hours after ingestion • Packed RBCs or whole blood transfusion if Owners should keep foods containing onion
but generally take 2-5 days to develop necessary. NOTE: new RBCs remain at risk or garlic out of their pets’ reach. Garlic and
○ Decreased hematocrit, elevated white for hemolytic damage if toxicant is still in onion should not be used to flavor foods or
blood cell count the blood (p. 1169). treats for pets.
○ Smears should be examined for Heinz • Oxygen supplementation is of limited benefit
bodies, evidence of regeneration because oxygen saturation of intact hemoglo- Technician Tips
○ With methemoglobinemia (p. 1365), bin remains high and methemoglobin binds When recommending baby food to stimulate
blood may appear brown and fail to turn oxygen poorly even with supplementation. appetite, it is important to remind clients to
red when exposed to air. • If necessary, manage hypotension, vomiting, avoid products with garlic or onion powder,
• Serum biochemical profile depends on degree or diarrhea. especially for cats.
of anemia, but increase in liver enzymes is
possible. Behavior/Exercise Client Education
• Urinalysis Limit exercise pending resolution of anemia. Garlic supplementation for the prevention of
○ Reddish brown color suggests hemoglo- fleas or heartworm disease is unsubstantiated
binuria (rule out hematuria, myoglobin- Drug Interactions and contraindicated.
uria). Garlic has an antithrombotic effect, and
○ Urine dipstick is positive for blood with concomitant use of garlic and drugs that alter SUGGESTED READING
hemoglobinuria or hematuria. platelet function (e.g., aspirin, clopidogrel) may Tang X, et al: An experimental study of hemolysis
○ Centrifuged urine remains reddish brown produce additive antithrombotic effects. induced by onion (Allium cepa) poisoning in dogs.
with hemoglobinuria, whereas the super- J Vet Pharmacol Ther 31:143-149, 2008.
natant of centrifuged urine clears with Possible Complications AUTHOR: Brandy R. Sobczak, DVM
hematuria. • Hemoglobinuria-associated renal tubular EDITOR: Tina Wismer, DVM, MS, DABVT, DABT
• If exposure history is unconfirmed, other damage possible in severe cases
tests may be indicated to explore alternative • Abortions can occur secondary to severe
causes for anemia/hemolysis hypoxemia if pronounced anemia is present.

Open-Mouth Jaw Locking Client Education
Sheet

BASIC INFORMATION Synonyms Epidemiology
Often confused with classic rostrodorsal luxa- SPECIES, AGE, SEX
Definition tion of the temporomandibular joint (TMJ) Cats and dogs of either sex; usually adult
Mouth is locked wide open due to displace- but showing different clinical/radiographic animals
ment of the coronoid process of the mandible signs and requiring entirely different treatment
ventrolateral to the zygomatic arch. approaches

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