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858 Pyrethrins/Pyrethroids Toxicosis

○ Enrofloxacin 10 mg/kg IV q 24h for thoracostomy tube placement in healthy dogs • Surgical treatment has been associated with a
dogs, 5 mg/kg IV q 24h for cats (use suggests avoidance of long-term indwelling better outcome than medical treatment alone
VetBooks.ir • Medical management • Long-term antibiotic therapy in all cases (4-6 may not apply in regions where grass awns
thoracostomy tubes.
for dogs. However, this varies by study and
with caution); does not treat anaerobes
○ Cefoxitin 22 mg/kg IV q 8h for dogs/cats
are rarely identified.
weeks minimum)
○ Bilateral thoracostomy tube placement (p.
1082) ○ Based on accurate identification of • Cats are more often successfully treated with
organism(s) involved
bilateral thoracostomy tubes and appropriate
○ Consider thoracic lavage q 6-8h with ○ Up to 3 months of therapy may be antimicrobial therapy.
body-temperature sterile saline. required. • Benefit of saline lavage as opposed to drainage
○ Serial cytologic evaluation of pleural alone is uncertain. Animals with thicker,
fluid to assess success of lavage therapy. Possible Complications more flocculent fluid are more likely to
Improvement includes change from Failure to resolve/recurrence of pyothorax: benefit.
degenerate neutrophils with intracellular • Cause not removed • Addition of antimicrobials or other drugs
or extracellular bacteria to nondegenerate • Failure of medical management: to lavage fluid is not indicated.
neutrophils without bacteria. ○ Ineffective pleural lavage • Bilateral thoracostomy tubes are helpful in
• Surgical management (more commonly ○ Ineffective/inappropriate antibiotic therapy aspiration and lavage of the pleural space.
indicated for dogs): thoracotomy indicated if • Antimicrobial therapy should be guided by
○ Definitive cause identified and retained in Recommended Monitoring culture and susceptibility, with attention
thoracic cavity (foreign body, lung lobe Thoracic radiographs at completion of antibiotic paid to Actinomyces and Nocardia and to
abscess) therapy and q 3 months for first year after Mycoplasma in cats.
○ Fluid loculated in the pleural space recovery • Obligate anaerobes are common in pyothorax
(lavage cannot access portions of fluid and are found in combination with aerobes;
accumulation) PROGNOSIS & OUTCOME antimicrobial treatment should be aimed at
○ Patient fails to respond to intensive both types of bacteria until culture results
medical therapy (4-5 days of pleural lavage • Surgical management, which may include are available.
and antibiotics) thoracoscopic debridement, is associated with
○ Actinomyces (in dogs, notoriously poor a better prognosis than medical management Technician Tips
response to medical management alone) in dogs with pyothorax in some studies; Knowledge of and experience in working
• Surgical management: aggressive debridement disease-free at 1 year: 78% (surgical) versus with thoracostomy tubes is important in the
of the pleural space, removal of underlying 25% (medical) management of patients with pyothorax:
cause if identified, thorough intraoperative • Development of fibrosing pleuritis is associ- • Used as the primary treatment modality for
lavage, and postoperative intermittent pleural ated with poor outcome. nonsurgical thoracic drainage and lavage
aspiration, lavage, and antimicrobial therapy • Lower heart rate and hypersalivation are • Used in the postoperative period for con-
○ Video-assisted thoracic surgery has been associated with poorer outcomes for cats. tinued thoracic drainage ± lavage
described for debridement in dogs. • Overall, 66% of cats and 80% of dogs can
Significant adhesions or inability to survive if treated appropriately. SUGGESTED READING
visualize critical structures should prompt Stillion JR, et al: A clinical review of the pathophysiol-
conversion to median sternotomy. PEARLS & CONSIDERATIONS ogy, diagnosis, and treatment of pyothorax in dogs
and cats. J Vet Emerg Crit Care 25:113-129, 2015.
Chronic Treatment Comments
• Thoracostomy tube removal based on overt • Intensive therapy should start immediately on AUTHOR: MaryAnn G. Radlinsky, DVM, MS, DACVS
EDITOR: Elizabeth A. Swanson, DVM, MS, DACVS
clinical and cytologic resolution of infec- diagnosis. Undertreatment is thought to be
tion. The incidence of infection related to a major contributor to morbidity/mortality.

Pyrethrins/Pyrethroids Toxicosis

BASIC INFORMATION • Pyrethrins and pyrethroids can be found in RISK FACTORS
a number of household and garden products Use of pyrethrins/pyrethroids in the environ-
Definition as well as topical flea and tick products. ment or on the animal
• Pyrethrins are derived from Chrysanthemum • Concentration is important in determining
flowers, and pyrethroids are synthetic toxicosis. Low-concentration products are GEOGRAPHY AND SEASONALITY
pyrethrins. relatively safe for dogs and cats, but con- More exposures during flea and tick season
• Pyrethroids are further divided into type centrated products can be toxic, especially and summer (home and lawn use)
I (lack a cyano group) and type II (with to cats. Clinical Presentation
an alpha-cyano group). Type I pyrethroids • Except for bifenthrin, most small exposures
include allethrin, bifenthrin, etofenprox, to pyrethroids in dogs do not result in sig- DISEASE FORMS/SUBTYPES
permethrin, phenothrin, resmethrin, and nificant clinical signs, but any concentrated • Ingestion can cause oral paresthesia, which can
tetramethrin. Type II pyrethroids include exposure in cats can lead to severe signs. manifest as hypersalivation, retching, gagging,
cyfluthrin, cyhalothrin, cypermethrin, Epidemiology and vomiting. Signs can be quite dramatic,
cyphenothrin, deltamethrin, esfenvalerate, but systemic toxicosis is not expected.
fenvalerate, flumethrin, lambda-cyhalothrin, SPECIES, AGE, SEX • Dermal exposure to pyrethrins/pyrethroids
and tralomethrin. Cats are more sensitive to pyrethroids than dogs. can result in dermal paresthesia in dogs (e.g.,

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