The trick is using enough poison to kill the parasites, but leave the pet unharmed. This means that Ivermectin dosage must be precisely calculated and carefully measured.
If you are considering treating your cat with Ivermectin, please consider as an alternative the best mange treatment.
Less visible symptoms:
According to PIM 292:
When Ivermectin is used properly, there may still be some unpleasant side-effects
caused by the sudden death of massive numbers of parasites:
rash, itchiness.
It is thought there are no long term effects from mild overdoses.
Signs Of Ivermectin Poisoning
The clinical signs of Ivermectin poisoning are:
Ivermectin acts on insects by potentiation of GABA-ergic
neural and neuromuscular transmission but since mammals
have only central GABA-ergic synapses which are to a
large extent protected by the blood-brain barrier they
are relatively resistant to ivermectin. Some
penetration of the blood-brain barrier does occur at
relatively high doses, with brain levels peaking between
two and five hours after administration. Symptoms seen
in a range of mammalian species are CNS depression, and
consequent ataxia, as might be expected from
potentiation of inhibitory GABA-ergic synapses (Hayes &
Laws, 1991).
Less Worrisome Things
According to PIM 292:
At recommended doses, ivermectin does not readily
penetrate the CNS of mammals, where GABA functions as a
neurotransmitter. The principal peripheral
neurotransmitter, acetylcholine, is unaffected by
ivermectin (MSD, 1988).
Dangers Due To Overdose
Of the various
signs of Ivermectin poisoning,
not all are life-threatening.
So where does the danger come from?
Respiratory Depression
According to studies on Rats and Dogs quoted in PIM 292,
high doses "cause death due to respiratory depression."
Ivermectin is teratogenic in rats, rabbit and mice at or near materno-toxic dose levels. The abnormalities are limited mainly to cleft palate. Mice are the most sensitive species to the effect of ivermectin with maternotoxicity at a dose of 0.2 mg/kg/day (MSD, 1988).
Treatment is symptomatic and supportive in cases of overdose. Adverse effects are transient, but analgesics and antihistamines may be required. Since ivermectin is believed to enhance GABA activity in animals, it is probably wise to avoid drugs that enhance GABA activity (benzodiazepines, barbiturates, valproate, valproic acid) in patients with potentially toxic ivermectin exposure (MSD, 1988)....
Supportive measures are indicated in case of life- threatening poisoning (which is rare). Analgesics and antihistamines are indicated for the treatment of adverse effects.
...
In case of ingestion of significant amounts of ivermectin, induce emesis using syrup of ipecac. Gastric lavage may be undertaken.
...
The efficacy of activated charcoal in gut decontamination following ingestion of ivermectin has not been documented and warrants investigation.
...
Some authors have suggested the use of picrotoxin and physostigmine as antidotal therapies. However, animal studies with these agents employing these agents as antidotes in ivermectin toxicity have been unsatisfactory and are not recommended (Iliff-Sizemore et al., 1990).
Tabulated Findings
I did a lot of research
on the web.
This section summarizes my findings.
WARNING: If you actually intend to use any of this information, check it with the original source. Watch out for outdated information and typographical errors!
"Depression, tremors, mydriasis, ataxia, coma and death
have been seen in Collie dogs at .100 mg/kg orally and
greater, but not at the recommended dose of the
commercial product (.006 mg/kg)." - PIM 292.
Animals Sensitive To Ivermectin
Animals Commonly Treated With Ivermectin
Drug Interactions
Therapeutic Ivermectin Dosage For Various Animals
Dosage in mg ivermectin per kg bodyweight.
| animal | dose | route | use | notes | reference |
|---|---|---|---|---|---|
| Cattle | 0.2 mg/kg | S.C. | G.I. roundworms, lungworms, warbles, mange mites, lice | Bimectin Datasheet | |
| Reindeer | 0.2 mg/kg | S.C. | larval stages of Hypoderma Tarandi | Bimectin Datasheet | |
| Pigs | 0.3 mg/kg | S.C. | G.I. roundworms, lungworms, mange mites, lice | Bimectin Datasheet | |
| Human, adult | .150 to .200 mg/kg | oral? | onchocerciasis and other parasitic infections | PIM 292 | |
| Human, children | .150 mg/kg | oral? | onchocerciasis and other parasitic infections | not for children weighing less than 15 kg | PIM 292 |
| ANIMAL | DOSE | ROUTE | USE | NOTES | REF |
S.C. = subcutaneous injection
Fatal Ivermectin Dosage For Various Animals
Dosage in mg ivermectin per kg bodyweight.
| animal | gender | LD50 dose | route | reference |
|---|---|---|---|---|
| Mouse | female | 24.6-41.6 mg/kg | oral | PIM 292 |
| Mouse | male | 11.6 mg/kg | oral | PIM 292 |
| Rat young adult | female | 44.3-52.8 mg/kg | oral | PIM 292 |
| Rat young adult | male | 42.8-52.8 mg/kg | oral | PIM 292 |
| Rat infant | male & female | 2.3 mg/kg | oral | PIM 292 |
| Rat | 660 mg/kg | dermal | PIM 292 | |
| ANIMAL | GENDER | DOSE | ROUTE | REF |
| animal | route | maximum plasma concentration | biological half-life | reference |
|---|---|---|---|---|
| Pigs | S.C.? | 3.5 days | 5.5 days | Bimectin Datasheet |
| Human | Oral | 10-12 hours | PIM 292 | |
| Rat | I.V. | 1 day | PIM 292 | |
| Cattle | Oral | 2.7 days | PIM 292 | |
| Cattle | S.C. | 2.9 days | PIM 292 | |
| Cattle | S.C.? | 5.5 days | 6 days | Bimectin Datasheet |
| Cattle | Topical | 15.9 days | PIM 292 | |
| ANIMAL | ROUTE | MAX-PLASMA | HALF-LIFE | REF |
S.C. = subcutaneous injection