Methocarbamol CRI for Symptomatic Treatment of Pyrethroid Intoxication: A Report of Three Cases

Abstract

Pyrethroids are popular for use in companion animals due to their relatively low mammalian toxicity and efficacy against arthropods. Nonetheless, pyrethroid intoxication has been reported in cats and dogs, and cats appear to be more susceptible due to difficulty in biotransformation and excretion of pyrethroids. Pyrethroid intoxications are generally due to either the improper use or accidental ingestion of approved products. Methocarbamol, given as intermittent injections, is a common first-line treatment choice for the tremors associated with pyrethroid intoxication. Two cats and one dog were treated with a methocarbamol continuous rate infusion (CRI) for pyrethroid intoxication. Clinical signs of toxicity resolved within a few hr in all three cases, with no adverse drug effects. A methocarbamol CRI can be considered in animals presenting with pyrethroid intoxication.

Treatment of severe lipophilic intoxications with intravenous lipid emulsion: a case series (2011–2014)

“…She was treated with a dose of midazolam and started on a methocarbamol CRI to control tremoring and also administered atropine to control parasympathetic nervous system signs. 25 Approximately 4 hours after presentation, she was still tremoring despite methocarbamol, and due to an absent gag reflex, she remained intubated without sedation. At that time, ILE was administered.…”

Tremor-Salivation Syndrome in Canine following Pyrethroid/Permethrin Intoxication

“…Effectiveness, low cost, the conception of "natural" compounds and low levels of systemic toxicity following dermal exposure had made those compounds the most commonly used home and garden insecticides in the U.S [1,3]. In the last decade, many reports describing permethrin toxicity in cats emerged, whereas canine intoxications were seldom reported in the literature [12][13][14][15][16][17][18][19][20][21]. The dog presented in this case was exposed to 2 different pyrethrins/pyrethroids compound calsses, namely Admiral®, consisting of 7.9% bifenthrin and Biospotix®, an insecticide containing 0.2% pyrethrum.…”

“…Consequently, the dog was treated with an anti-convulsant (diazepam), tremor control and supportive care, eventually leading to a full recovery. Diagnosis of pyrethrin toxicosis is generally based on history of exposure and typical clinical signs, which commonly include hyperexcitability, generalized tremors and seizures [12][13][14][15][16][17][18][19][20][21]. The dog in this case exhibited clinical signs consistent with the TS-syndrome, most likely explained by concomitant exposure to pyrethrum and bifenthrin.…”

“…Deficiency of hepatic glucuronosyl transferase has been suggested as a potential explanation for their increased sensitivity [11,12]. Numerous reports have been published in the veterinary literature regarding permethrin toxicity in cats, however to the best of our knowledge, pyrethrin or pyrethroid toxicities are rarely reported in dogs [20,21]. This Case report describes acute pyrethroid toxicity in a king Charles cavalier dog.…”

In dogs with metaldehyde intoxication, are benzodiazepines more effective than methocarbamol in relaxing muscles and reducing tremors?

“…Its peak levels in humans occur approximately 2 hours after dosing, and its serum half-life is about 1-2 hours (Plumb, 2008). In the US, methocarbamol IV is available as well, and successful management of tremors has been reported with methocarbamol CRI in cats (Draper et al, 2013). Methocarbamol's major drawbacks include: (a) limited routes of administration in combination with availability limited to the oral form in Europe; (b) delayed onset of action compared to benzodiazepines IV; and (c) central nervous system depressant effects as a carbamate (sedation, salivation, lethargy, weakness, ataxia) (Plumb, 2008).…”