Intravenous lipid emulsion therapy in 20 cats accidentally overdosed with ivermectin

Clinical effects and adverse effects of intravenous lipid emulsion treatment in dogs and cats with suspected poisoning

This retrospective study aimed to evaluate the effects on the clinical signs of poisoning and adverse effects of intravenous lipid emulsion treatment in 82 animals (dogs and cats) with suspected poisonings over 18 months. Physical examination parameters and state of consciousness were documented every hour after the intravenous administration of a bolus of 2 ml/kg and 0.25 ml/kg/min over 60 minutes of a 20% intravenous lipid emulsion. The modified Glasgow coma scale and laboratory findings (blood gas analysis, triglyceride, lactate) were evaluated initially and three hours after discontinuing intravenous lipid emulsion administration. A statistical evaluation of the occurrence of adverse effects and the development of laboratory values was performed. A decrease in respiratory rate in the second control (8-12 hours) after ILE was observed. Three hours after completing of the intravenous lipid emulsion, triglyceride concentration increased about 10 times (p <0.001). Venous carbon dioxide partial pressure, bicarbonate, base excess, as well as the electrolytes sodium, potassium and ionized calcium decreased significantly (p <0.001). Patients who experienced a worsening of the modified Glasgow coma scale had a higher increase in triglyceride concentrations (p = 0.041) and plasma lactate (p = 0.034) and a larger decrease in bicarbonate concentrations (p = 0.053) compared to others. About 54% (n = 44) of the patients showed adverse effects which could be attributed to the administration of intravenous lipid emulsion and may be associated with a higher triglyceride increase. All of them were completely reversible within 33 hours. Adverse effects associated with intravenous lipid emulsion therapy were observed in half of the patients and were associated with a higher increase in triglycerides.

Alpha-chloralose poisoning in 25 cats: clinical picture and evaluation of treatment with intravenous lipid emulsion

OBJECTIVES

The aims of this study were to describe the clinical picture and progression in cats with alpha-chloralose (AC) intoxication and to determine if treatment with intravenous (IV) lipid emulsion (ILE) influenced either the serum concentration of AC or the clinical signs.

METHODS

Cats with suspected AC poisoning admitted to a university small animal hospital were included. The cats were randomised into two groups: one receiving 20% ILE at a dose of 300 mg/kg as a 2 min bolus, followed by a 1500 mg/kg continuous rate infusion over 30 mins (IL+ group) and the other receiving IV fluid therapy with Ringer's acetate (IL- group). Serum samples were drawn at 0, 2, 12 and 24 h after admission. Samples were tested for AC with a novel validated, quantitative, ultra-high-performance liquid chromatography-tandem mass spectrometry method. Vital and predefined clinical signs were noted at the times of sampling and patients were scored using a previously described intoxication severity score. Telephone interviews were conducted after discharge to assess outcome.

RESULTS

A total of 25 cats were enrolled: 13 cats in the IL+ group and 12 in the IL- group. The most common clinical signs at presentation were tremor (n = 22, 88.0%), cranial nerve deficits (n = 20, 80.0%) and bradycardia (n = 19, 76.0%). No significant difference in AC concentration or change in intoxication score over time was found between the IL+ and IL- groups at any time point (P >0.05). All cats recovered within 72 h.

CONCLUSIONS AND RELEVANCE

ILE did not have any effect on the AC serum concentration or clinical signs in AC-poisoned cats. All cats survived until follow-up. In cats with an acute onset of the described neurological signs, AC intoxication is an important differential diagnosis with an excellent prognosis.

The effect of intravenous lipid emulsion (ILE) on the pharmacokinetic/toxicokinetic dispositions of ivermectin and carprofen in rabbits

Intravenous lipid emulsion (ILE) has been widely used as an effective antidote in both veterinary and human medicine for the treatment of acute intoxications caused by drugs and pesticides with high lipid solubility. This study was conducted to investigate the effect of ILE co-administration on the kinetic dispositions of ivermectin (IVM) and carprofen (CRP) following intravenous bolus administration at subtoxic doses in rabbits.Twenty-four male New Zealand rabbits weighing 2.78 ± 0.2 kg were used in this study. Rabbits were divided into four groups (Group 1: IVM and Group 2: IVM + ILE or Group 3: CRP and Group 4: CRP + ILE), each group consisting of 6 animals. In the IVM study, Group 1 received IVM (0.6 mg/kg) alone while Group 2 received IVM (0.6 mg/kg) and ILE (2.5 ml/kg). In the CRP study, Group 3 received CRP (12 mg/kg) alone while Group 4 received CRP (12 mg/kg) and ILE (2.5 ml/kg). In both drug groups, ILE was administered 3 times as an i.v. bolus at the 10th min and repeated 4th and 8th h after the drug administration. Blood samples were collected from the auricular vein at various times after drug administration. The drug concentrations in plasma samples were determined by high-pressure liquid chromatography. Kinetic parameters were calculated using a non-compartmental model for both CRP and IVM.The C0 and area under the concentration-time curve from zero up to ∞ (AUC0-∞) values were significantly greater with ILE co-administration (2136 ng/ml and 360.84 ng.d/ml) compared to the IVM alone (1340.63 ng/ml and 206 ng.d/ml), respectively. Moreover, the volume of distribution (Vdss) and clearance (Cl) of IVM were reduced by approximately 42% and 46% with ILE co-administration compared to IVM alone resulting in a reduction of the distribution and slower elimination, respectively. Similar differences in C0, and Vdss values were also observed in CRP with ILE co-administration compared to CRP alone. ILE co-administration changed significantly the kinetic profile of both IVM and CRP in rabbits, supporting the lipid sink theory in which highly lipid-soluble compounds are absorbed into the lipid phase of plasma from peripheral organs such as the heart and brain affected by the acute toxicity of the compounds.

Intravenous lipid emulsion for the treatment of poisonings in 313 dogs and 100 cats (2016-2020)

Introduction

The aim of this retrospective study was to analyze the effect and potential adverse effects of intravenous lipid emulsion (ILE) in poisoned dogs and cats over a 5 years period.

Methods

Medical records of 313 dogs and 100 cats receiving ILE between 2016-2020 were analyzed for suspected toxicant, clinical signs, ILE dosages and frequency, the effect and adverse effects of ILE, and patient outcome.

Results

Dogs and cats were poisoned with mostly unidentified toxicants (48%), rodenticides (8%), recreational drugs and nuts (7% each) and other toxicants. Clinical signs included neurologic deficits (63%), cardiovascular signs (29%), thermoregulation (21%) or gastrointestinal abnormalities (17%). Treatment with ILE was initiated within a median of 6.0 h (1.0-91.0 h) after poisoning. Dogs and cats received a total amount of median 8.0 mL/kg (1.5-66.6 mL/kg) and 15.8 mL/kg (1.8-69.4 mL/kg) ILE, respectively. A positive effect was observed in 74% of the patients, whereas clinical signs worsened in 4% of the patients after ILE administration. No subjective effect was detected in 22% of the patients. Suspected or possible adverse effects of ILE occurred in 6% of the patients, including neurological signs (temporarily reduced consciousness and ataxia), bradycardia, hyperthermia, vomiting, diarrhea, respiratory distress, worsening of the general behavior, facial swelling, and thrombophlebitis. The overall survival rate was 96%. One dog who potentially experienced adverse events was euthanized.

Conclusion

ILE treatment was successful in most patients but can be associated with adverse effects. Administration of ILE should be carefully selected on an individual basis after weighing the possible benefits against potential adverse effects.

Detection of the ABCB11930_1931del TC Mutation in Two Suspected Ivermectin-Sensitive Cats and Their Relatives by a Novel TaqMan Allelic Discrimination Assay

The multidrug resistance gene MDR1 (syn. ABCB1) encodes for the multidrug efflux transporter P-glycoprotein (P-gp), which is highly expressed at the blood-brain barrier and protects the brain from potentially neurotoxic compounds, such as ivermectin. MDR1 mutation in dogs is known to be linked to dramatically increased brain accumulation of ivermectin and life-threatening neurological toxicity. The present report describes two suspected ivermectin-sensitive Maine Coon cats, which exhibited neurological toxicity following subcutaneous application of therapeutic doses of ivermectin. Both cats showed a homozygous 2-bp deletion in the MDR1/ABCB1 coding sequence (ABCB11930_1931del TC, syn. MDR1 nt1930(del2)) that had previously been associated with a drug-sensitive phenotype in cats. For cat MDR1 genotyping, a novel TaqMan allelic discrimination assay was established and validated. This assay was used for ABCB11930_1931del TC genotyping of the drug-sensitive cats as well as of more than 50 relatives. About half of them had the heterozygous MDR1(+/-) genotype, while none of these related cats with former ivermectin treatment had a history of drug-sensitivity. In conclusion: The present study supports previous findings on drug-sensitivity in cats with homozygous ABCB11930_1931del TC mutation. The newly established TaqMan allelic discrimination assay provides a useful and reliable method for routine MDR1 genotyping in cats in order to identify drug-sensitive cats prior to treatment with established P-gp substrates such as ivermectin and other macrocyclic lactones and thus to improve therapeutic safety.

Role of an ABCB11930_1931del TC gene mutation in a temporal cluster of macrocyclic lactone-induced neurologic toxicosis in cats associated with products labeled for companion animal use

OBJECTIVE

To determine whether ABCB11930_1931del TC predisposed cats to macrocyclic-lactone toxicosis and the frequency of the ABCB11930_1931del TC gene mutation in banked feline DNA samples.

SAMPLE

DNA samples from 5 cats presented for neurologic clinical signs presumed to be caused by exposure to macrocyclic lactones and 1,006 banked feline DNA samples.

PROCEDURES

The medical history pertaining to 5 cats was obtained from veterinarians who examined, treated, or performed necropsies on them. The DNA from these 5 cats and 1,006 banked feline samples were analyzed for the presence of the ABCB11930_1931del TC genotype.

RESULTS

4 of the 5 cats with neurologic signs presumed to be associated with macrocyclic-lactone exposure were homozygous for ABCB11930_1931del TC. The other cat had unilateral vestibular signs not typical of macrocyclic-lactone toxicosis. The distribution of genotypes from the banked feline DNA samples was as follows: 0 homozygous for ABCB11930_1931del TC, 47 heterozygous for ABCB11930_1931del TC, and 959 homozygous for the wild-type ABCB1 allele. Among the 47 cats with the mutant ABCB1 allele, only 3 were purebred (Ragdoll, Russian Blue, and Siamese).

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested a strong relationship between homozygosity for ABCB11930_1931del TC and neurologic toxicosis after topical application with eprinomectin-containing antiparasitic products labeled for use in cats. Although this genotype is likely rare in the general cat population, veterinarians should be aware of this genetic mutation in cats and its potential for enhancing susceptibility to adverse drug reactions.

USE OF FLUMETHRIN-IMPREGNATED COLLARS TO MANAGE AN EPIDEMIC OF SARCOPTIC MANGE IN AN URBAN POPULATION OF ENDANGERED SAN JOAQUIN KIT FOXES (VULPES MACROTIS MUTICA)

Sarcoptic mange epidemics can have long-lasting impacts on susceptible wildlife populations, potentially contributing to local population declines and extirpation. Since 2013, there have been 460 reported cases of sarcoptic mange in an urban population of endangered San Joaquin kit foxes (Vulpes macrotis mutica) in Bakersfield, CA, with many of them resulting in fatality. As part of a multifaceted response to mitigate mange-caused mortalities and reduce this conservation threat, a 2-yr randomized field trial was conducted to assess the efficacy of long-acting flumethrin collars against sarcoptic mange in kit foxes. Thirty-five kit foxes living in a high-density population on a college campus were captured, examined, administered selamectin, and each fox randomly assigned to either receive a flumethrin collar placed within a VHF radio collar or a VHF radio collar without flumethrin. The survival and mange-infestation status of study animals was monitored via radio telemetry, remote cameras, and periodic recapture examinations and compared among treated and control kit foxes using a Cox proportional hazards model. The average time to onset of mange for treated kit foxes (176 days) was similar to controls (171 days) and treatment with flumethrin did not significantly reduce mange risk for all kit foxes. Kit foxes that had a mild mange infestation at the beginning of the study were four times more likely to develop mange again, regardless of flumethrin treatment, compared with kit foxes that had no signs at initial recruitment. This study demonstrates an approach to evaluating population-level protection and contributes to the limited literature on efficacy, safety, and practicality of acaricides in free-ranging wildlife.

Intravenous lipid emulsion treatment in rabbits with ivermectin toxicosis

OBJECTIVE

To determine the effect and safety of IV lipid emulsion in rabbits with acute ivermectin toxicosis.

DESIGN

Randomized controlled trial.

SETTING

University research facility.

ANIMALS

Twenty-four healthy male adult New Zealand rabbits.

INTERVENTIONS

Three groups of rabbits (IV, IV_RL, and IV_LE) received 80 mg/kg of ivermectin (8 mL/kg) through a nasogastric tube, and 1 group (LE) received an equivalent volume (8 mL/kg) of 0.9% sodium chloride. Group IV_RL was treated with Ringer's lactate (2 mL/kg bolus, followed by 0.25 mL/kg/min for 60 minutes), whereas groups IV_LE and LE received 20% lipid emulsion. The rabbits were submitted to clinical and neurological evaluation, and blood samples were collected for biochemical analysis. All animals were euthanized, and tissue samples were collected and processed for histopathological evaluation and ivermectin quantification.

MEASUREMENTS AND MAIN RESULTS

All animals exposed to ivermectin manifested clinical changes consistent with toxicosis, but the ones that received IV lipid emulsion infusion showed no significant clinical improvement. Intense increase in serum glucose and triglyceride concentrations was seen after ivermectin exposure, along with increased urea and creatinine concentrations, but the last 2 remained within the reference range. Lipid emulsion caused an intense increase in triglycerides and cholesterol concentrations. No pathological abnormalities were seen in the organs sampled. Toxicological analysis showed greater ivermectin concentration in adipose tissue and liver, followed by kidney and, finally, brain. The treatments did not change ivermectin tissue concentration.

CONCLUSIONS

When given to rabbits intoxicated with ivermectin, IV lipid emulsion was biochemically and histologically safe but was not effective in treating, delaying, or reversing clinical signs and progression, nor did it alter ivermectin tissue concentration.

SUSPECTED MOXIDECTIN TOXICOSIS IN A ROAN ANTELOPE (HIPPOTRAGUS EQUINUS), A SABLE ANTELOPE (HIPPOTRAGUS NIGER), AND AN ARABIAN ORYX (ORYX LEUCORYX) AT A SEMI-FREE RANGE ZOOLOGICAL PARK

Moxidectin is a commonly used lipophilic anthelmintic with activity against a wide range of nematodes. It is labeled for use in cattle by oral, topical, and subcutaneous routes. In semi-free ranging conditions, many anthelmintics are remotely administered intramuscularly due to an inability to administer by other routes without restraint. During 2015-2016, three animals including a roan (Hippotragus equinus), sable (Hippotragus niger), and Arabian oryx (Oryx leucoryx) treated with moxidectin developed clinical signs consistent with toxicosis. The primary sign was severe neurologic depression within 12 to 24 hr. Based on recommendations in domestic cases, animals were treated with intravenous lipid therapy and supportive care while diagnostic testing was performed. All three initially improved prior to succumbing to secondary problems associated with prolonged recumbency. Moxidectin has been administered remotely on 97 occasions in eight different exotic ruminant species at Fossil Rim, with only the above three cases showing clinical signs of toxicosis. Two potential causes in these cases include poor body condition leading to a smaller volume of distribution, thus allowing higher concentrations to overwhelm the blood-brain barrier, or a genetic defect similar to some herding dog breeds. Given that cases were seen in three different species at an overall low incidence within a given species, a genetic defect is considered unlikely. The animals affected did have significantly lower body condition score than conspecifics, and it is considered likely that this predisposed these animals to toxicosis. Therefore, caution should be used when administering moxidectin intramuscularly in animals in poor body condition.

Oxidative red blood cell damage associated with propofol and intravenous lipid emulsion therapy in a dog treated for 5-fluorouracil toxicosis

OBJECTIVE

To describe the first documented case of oxidant-induced anemia in a dog associated with propofol and IV lipid emulsion (IVLE) treatment for 5-fluorouracil (5-FU) toxicosis.

CASE SUMMARY

A 2-year-old male intact mixed breed dog was presented for evaluation after ingestion of 5% 5-FU cream. Refractory reactive seizures rapidly developed, and treatment with benzodiazepines, propofol, levetiracetam, and IVLE was initiated. The dog was euthanized due to development of marked oxidant-induced anemia.

NEW INFORMATION PROVIDED

This report documents the first instance of oxidant-induced anemia in the dog, associated with propofol and IVLE infusion therapy prescribed for treatment of 5-FU toxicosis.

Intravenous Lipid Emulsions in Veterinary Clinical Toxicology

Use of intravenous lipid emulsion (ILE) as an antidote for severe cardiotoxicity and neurotoxicity has expanded in the veterinary world in the past decade. Despite advances in understanding of potential mechanisms of action of antidotal ILE, knowledge gaps remain in efficacy, appropriate dosing rates for various toxicants, and potential adverse reactions. Use of ILE in management of toxicoses of veterinary patients should be considered investigational, and should not be first-line treatment of most toxicoses, especially where established treatment protocols have good likelihood of positive outcomes. Use of ILE in veterinary toxicology cases requires judicious assessment of individual cases and proper informed consent of clients.

Electroretinographic changes after intravenous lipid emulsion therapy in a dog and a foal with ivermectin toxicosis

This case report describes ivermectin-induced blindness in a dog and a foal with normal ophthalmic fundic examinations and attenuated electroretinography (ERG). Subsequent recovery in ERG was noted following intravenous lipid emulsion (ILE) therapy. A dog and a foal were evaluated for ivermectin-induced blindness. Clinical signs included dull mentation, absent pupillary light reflexes (PLRs), and absent menace on presentation. The animals had normal fundoscopic examinations; however, in both cases ERG was consistent with neurosensory retinal dysfunction. Following ILE therapy for ivermectin toxicosis, return of menace, PLRs, and normal mentation were noted, as was improvement in ERG and serum ivermectin levels. These are the first documented cases of ivermectin-induced blindness in a dog and a foal with normal fundic examinations and attenuated ERG. ERG improved in both animals after ILE therapy. ERG may assist in the diagnosis of ivermectin toxicosis in dogs and horses. ILE therapy may hasten recovery in treatment of ivermectin-induced blindness.