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614 Malassezia Dermatitis

Clinical Presentation • Serum biochemistry profile: mild elevations be used to control tremors but is usually
DISEASE FORMS/SUBTYPES of serum triglycerides, lipase, and alkaline not needed
VetBooks.ir part of a food item (e.g., chocolate toxicosis). changes are expected to return to normal Possible Complications
phosphatase have been reported; mild
Other signs may be seen if macadamia nuts are
Pancreatitis can be seen if macadamia nuts are
within 48 hours.
HISTORY, CHIEF COMPLAINT
• Evidence of exposure to macadamia nuts Advanced or Confirmatory Testing part of baked goods or other food items.
• Macadamia nuts in stool or vomitus Diagnostic lab tests as needed to rule out other Recommended Monitoring
• Presence of consistent clinical signs causes for the signs In severe cases, monitor temperature, hydration
status, and electrolytes.
PHYSICAL EXAM FINDINGS TREATMENT
• Lethargy, depression PROGNOSIS & OUTCOME
• Vomiting, abdominal pain Treatment Overview
• Ataxia, weakness (hindlimb > forelimb), Decontamination with emesis if exposure is Full recovery is expected within 12-48 hours.
tremors or trembling, muscle stiffness recent and no signs are present. Activated
• Hyperthermia charcoal is not typically indicated. Provide PEARLS & CONSIDERATIONS
symptomatic and supportive care as needed.
Etiology and Pathophysiology Many cases are self-limited and can be managed Comments
• The mechanism of action for macadamia on an outpatient basis. Consider antiemetic, • Avoid overly aggressive decontamination and
nut toxicosis in dogs is not known. IV fluids, and thermoregulation for significant treatment. Activated charcoal may pose more
• 1 g/kg may warrant decontamination and signs. Complications are rare, and signs are serious risks than macadamia nut toxicosis
monitoring (average weight is 2.6-5 g/nut). expected to resolve in 12-48 hours. and is not indicated in these cases.
○ Severity of signs correlates with dosage • Ask owners about other potential concerns
Acute General Treatment for toxicosis regarding the macadamia nut
DIAGNOSIS • Decontamination of patient (p. 1087): product, such as chocolate coating (p. 159),
○ Emesis (within 4 hours of ingestion in onion/garlic (p. 707), and spices.
Diagnostic Overview asymptomatic dog) (p. 1188)
The diagnosis is based on the history of known ○ Apomorphine 0.03-0.04 mg/kg IV or IM, Prevention
or suspected exposure to macadamia nuts and or crush tablet portion with water and Keep all macadamia nuts away from dogs.
development of consistent clinical signs, usually instill into conjunctival sac, rinsing after
within 12 hours of exposure. There are no emesis, or Technician Tips
diagnostic tests available. ○ Hydrogen peroxide 3% 2.2 mL/kg, max If the dog is managed as an outpatient, advise
dose 45 mL PO, repeat in 10-15 minutes owners to confine (away from furniture and
Differential Diagnosis if no vomiting stairs) at home to prevent injury if ataxia or
• Toxins (e.g., ethanol, avermectins, barbi- ○ Activated charcoal: not recommended. weakness develops. Discuss nursing care, such
turates, benzodiazepines, DL-methionine, Macadamia nut toxicosis is not life- as offering food and water by hand and assisting
black walnut, organic fertilizer, bromethalin, threatening, and there is some risk for walking with a sling to facilitate elimination
ethylene glycol, marijuana, tremorgens) potentially life-threatening complications outside.
• Orthopedic disorders associated with activated charcoal (e.g.,
• Neuromuscular disorders aspiration pneumonia, hypernatremia). Client Education
• Pancreatitis ○ Warm tap water enema 5-10 mL/kg Assure clients that the signs of macadamia nut
• Infectious diseases may be considered for large ingestions toxicosis are transient and not life-threatening.
• Trauma to reduce transit time through the GI
• Electrolyte disturbances tract and potentially shorten the duration SUGGESTED READING
• Spinal disease of signs. Gwaltney-Brant SM: Macadamia nuts. In Peterson
• Symptomatic and supportive care ME, et al, editors: Small animal toxicology, ed 3,
Initial Database ○ Antiemetic: maropitant 1 mg/kg SQ q St. Louis, 2013, Elsevier, pp 625-627.
• Complete physical exam to rule out other 24h AUTHOR: Colette Wegenast, DVM
causes for the signs ○ IV fluids: if tremors, monitor urine color EDITOR: Tina Wismer, DVM, MS, DABVT, DABT
• Abdominal radiographs may reveal large for myoglobinuria
amount of ingesta in stomach. ○ Thermoregulation
• Examine stomach contents (if vomiting) and ○ Methocarbamol 55-220 mg/kg IV, repeat
feces for evidence of macadamia nuts. as needed; max dose (330 mg/kg/day) may

Malassezia Dermatitis Bonus Material Client Education
Sheet
Online
Epidemiology
BASIC INFORMATION • Terriers, shih tzu, dachshund, Shar-pei,
SPECIES, AGE, SEX spaniel, basset hound, and German shepherd
Definition Very common in dogs of all ages; uncommon dogs seem to be predisposed, likely due to
This very common pruritic dermatosis is caused in cats of any age; either sex underlying conditions favorable to yeast
by the overgrowth of Malassezia spp yeast. overgrowth.
Most infections are caused by the lipophilic GENETICS, BREED PREDISPOSITION • Devon rex cats are more susceptible.
unicellular organism Malassezia pachydermatis. • May occur in any breed of dog or cat

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