• TABLE OF CONTENTS
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 Experiment
 Results and discussion
 Conclusion














Group Title: Department of Animal Science research report - Florida Agricultural Experiment Station ; AL-1983-2
Title: Safety of Ivermectin in pregnant mares
CITATION PAGE IMAGE ZOOMABLE
Full Citation
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Permanent Link: http://ufdc.ufl.edu/UF00073146/00001
 Material Information
Title: Safety of Ivermectin in pregnant mares
Series Title: Department of Animal Science research report
Physical Description: 2 leaves : ; 28 cm.
Language: English
Creator: Asquith, Richard L
University of Florida -- Dept. of Animal Science
University of Florida -- Agricultural Experiment Station
Publisher: Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1983
 Subjects
Subject: Mares -- Pregnancy -- Florida   ( lcsh )
Mares -- Parasites -- Control -- Florida   ( lcsh )
Ivermectin -- Safety measures   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: R.L. Asquith ... et al..
General Note: Caption title.
General Note: "June, 1983."
Funding: Animal science research report (University of Florida. Dept. of Animal Science) ;
 Record Information
Bibliographic ID: UF00073146
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 81148822

Table of Contents
    Experiment
        Page 1
    Results and discussion
        Page 1
    Conclusion
        Page 2
Full Text

Department of Animal Science Florida Agricultural
Research Report AL-1983-2 Experiment .Station
June, 1983 Gainesville, Florida

SAFETY OF IVERMECTIN IN PREGNANT MARES

R. L. Asquith1, J. Kivipelto2, R. E. Plue3 and R. L.'e d3 L RARY

Ivermectin (Eqvalan) an injectable product for control f gas i epap -nal
nematodes and bots of horses is derived from the avermectin family of compounds.
The avermectins are broad spectrum antiparasitic agents iso a f rop, fermentation
products of Streptomyces avermitilis an organism found in s e#Ocid fOPrida
ivermectin on both external and internal parasites is by inhibition of tKesT
transmission from the ventral cord interneurons to the excitatory motor neurons.
This inhibitory action is a result of the release of gamma aminobutyric acid
(GABA). The parasites becomes paralyzed and eventually die. However, the iver-
mectin does not penetrate into the central nervous system of mammals and this
provides for a wide safety margin in the animal being treated. Extensive trials
have demonstrated the safety and efficacy of ivermectin in horses. The purpose of
this trial was to determine the safety of ivermectin when administered to pregnant
mares at 60 day intervals from 90 days after breeding to foaling.

Experiment

Animals Fifteen pregnant mares of various breeds were used in this study
and were placed on the experiment at staggered starts contingent to pregnancy
determination. All of the mares were part of the production herd of the Horse
Research Center and had been kept in fecal contaminated pastures prior to assign-
ment. Mares approaching 3 months of pregnancy, determined by the last recorded
ovulation, last breeding, and by sequential rectal palpation were assigned to the
experiment.

Animals were allocated to one of 3 treatment groups. Five replicates were
included in this study. An attempt was made to include mares of several breeds
in each treatment group considering the small population of pregnant mares avail-
able.

The treatment groups were: Group A receiving ivermectin at 600 mcg/kg by
intramuscular injections at 60 day intervals, Group B receiving a placebo (vehicle)
by intramuscular injections at the same volume at 60 day intervals, and Group C
received no medication during the trial. The first treatment day was designated
as day 0. Each mare was weighed, blood samples drawn, and fecal samples obtained
prior to being placed on the trial and the initial treatment.

Hematocrit percentage, hemoglobin level, and plasma arginase level were
measured every two weeks during the trial. Fecal samples were also collected
every two weeks and the number of parasitic ova per gram of feces (EPG) was de-
termined by a modified McMaster technique.

Results and Discussion

No deaths nor abortions occurred during the trial; all fifteen mares gave
birth to live foals. The treated mares did not evidence adverse reactions to
the dose level of ivermectin (three times the recommended dose) nor did the



1. Asquith, DVM, Assoc. Professor of Equine Health
2. Kivipelto, B.S., Chemist II, Department of Animal Science
3. Plue, DVM and Seward, DVM, Merck & Co., Inc., P. O. Box 2000, Rahway, New Jersey





Department of Animal Science Florida Agricultural
Research Report AL-1983-2 Experiment .Station
June, 1983 Gainesville, Florida

SAFETY OF IVERMECTIN IN PREGNANT MARES

R. L. Asquith1, J. Kivipelto2, R. E. Plue3 and R. L.'e d3 L RARY

Ivermectin (Eqvalan) an injectable product for control f gas i epap -nal
nematodes and bots of horses is derived from the avermectin family of compounds.
The avermectins are broad spectrum antiparasitic agents iso a f rop, fermentation
products of Streptomyces avermitilis an organism found in s e#Ocid fOPrida
ivermectin on both external and internal parasites is by inhibition of tKesT
transmission from the ventral cord interneurons to the excitatory motor neurons.
This inhibitory action is a result of the release of gamma aminobutyric acid
(GABA). The parasites becomes paralyzed and eventually die. However, the iver-
mectin does not penetrate into the central nervous system of mammals and this
provides for a wide safety margin in the animal being treated. Extensive trials
have demonstrated the safety and efficacy of ivermectin in horses. The purpose of
this trial was to determine the safety of ivermectin when administered to pregnant
mares at 60 day intervals from 90 days after breeding to foaling.

Experiment

Animals Fifteen pregnant mares of various breeds were used in this study
and were placed on the experiment at staggered starts contingent to pregnancy
determination. All of the mares were part of the production herd of the Horse
Research Center and had been kept in fecal contaminated pastures prior to assign-
ment. Mares approaching 3 months of pregnancy, determined by the last recorded
ovulation, last breeding, and by sequential rectal palpation were assigned to the
experiment.

Animals were allocated to one of 3 treatment groups. Five replicates were
included in this study. An attempt was made to include mares of several breeds
in each treatment group considering the small population of pregnant mares avail-
able.

The treatment groups were: Group A receiving ivermectin at 600 mcg/kg by
intramuscular injections at 60 day intervals, Group B receiving a placebo (vehicle)
by intramuscular injections at the same volume at 60 day intervals, and Group C
received no medication during the trial. The first treatment day was designated
as day 0. Each mare was weighed, blood samples drawn, and fecal samples obtained
prior to being placed on the trial and the initial treatment.

Hematocrit percentage, hemoglobin level, and plasma arginase level were
measured every two weeks during the trial. Fecal samples were also collected
every two weeks and the number of parasitic ova per gram of feces (EPG) was de-
termined by a modified McMaster technique.

Results and Discussion

No deaths nor abortions occurred during the trial; all fifteen mares gave
birth to live foals. The treated mares did not evidence adverse reactions to
the dose level of ivermectin (three times the recommended dose) nor did the



1. Asquith, DVM, Assoc. Professor of Equine Health
2. Kivipelto, B.S., Chemist II, Department of Animal Science
3. Plue, DVM and Seward, DVM, Merck & Co., Inc., P. O. Box 2000, Rahway, New Jersey








plasma arginase levels suggest liver damage at any point during the trial.' There
were no significant differences between the ivermectin and the other two groups,
nor between the control and vehicle groups, for any of the blood chemistry or weight
variables analyzed. Mares treated with ivermectin had significantly (P<0.01) lower
EPG counts than control or vehicle-treated mares throughout the trial; no strongyle
eggs were recovered from any ivermectin-treated mare at any point after initiation
of treatment. There were no significant differences between EPG counts in the
control and vehicle groups at any stage of the trial.

Conclusions

These results suggest that ivermectin, when used as an injectable anthelmintic,
is a safe and efficacious means of treating the pregnant mare after three months of
pregnancy and at two-month intervals thereafter. No detrimental effects on overall
health or reproductive performance were observed.


SUMMARY OF EPG DATA


Variable

Number of Mares

Observation Period

Day 0

Days 14 56-

Days 70 112

Days 126 168

-Day 182.- _Foaling

Foaling Trial Termination

Day 14 Trial Termination

1
Retransformed means, based on


Treatment
Ivermectin
Control Vehicle 600 mcg/kg

5 5 5



426.6 527.3 1035.0

779.6 857.6 0

785.0 165.9 0

561.9 197.8 0

860.5 701.9 0

1141.0 599.5 0

804.8 412.0 0


In (EPG+1) transformation.




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