Group Title: Veterinary Science mimeograph series
Title: Field trials with thiabendazole and dichlorvos in the treatment of Strongyloides ransomi infection of pigs
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Permanent Link: http://ufdc.ufl.edu/UF00094192/00001
 Material Information
Title: Field trials with thiabendazole and dichlorvos in the treatment of Strongyloides ransomi infection of pigs
Alternate Title: Veterinary Science mimeograph series - University of Florida ; VY67-4
Physical Description: 4, 2 leaves : ; 28 cm.
Language: English
Creator: Leland, Stanley Edward, 1926-
Neal, F. C.
Plummer, Charles B.
University of Florida -- Agricultural Experiment Station
Donor: unknown ( endowment )
Publisher: Florida Agricultural Experiment Stations
Place of Publication: Gainesville, Fla.
Publication Date: June, 1967
Copyright Date: 1967
 Subjects
Subject: Swine -- Diseases and pests -- Florida   ( lcsh )
Strongyloidiasis -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: S.E. Leland, Jr., F.C. Neal, and C.B. Plummer, Jr.
General Note: Caption title.
General Note: "June, 1967."
 Record Information
Bibliographic ID: UF00094192
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 433106023

Full Text


Department of Veterinary Science Florida Agricultural
Miimeograph Series No. VY67-4 Experiment Station
9-Vune, 1967 Gainesville, Florida

Field Trials with Thiabendazole and Dichlorvos
in the Treatment of Strongyloides ransomi Infection of Pigs

S.E. Leland, Jr., Ph.D., F.C. Neal, D.V.M., M.S.
and
C.B. Plummer, Jr., D.V.M.

Summary

Thiabendazole* at the rate of 1 lb./1,000 lbs. feed for a 14 day
period was very effective in eliminating the eggs of Strongyloides
ransomi from the feces of weanling pigs which were recovering from
a severe outbreak. A single feeding of dichlorvos** was only parti-
ally effective in eliminating the eggs from the feces. Neither
medication was effective in increasing body weights statistically
in pigs having severe clinical signs of parasitism at the time of
treatment.

Thiabendazole Paste+ was also effective in reducing the number of
eggs of S. ransomi in suckling pigs. However, where the medicated
feeding schedule was used in pigs with access to sow's milk and un-
medicated sow's feed, the reduced intake of medicated feed resulted
in incomplete elimination of eggs from the feces.

Introduction

As indicated by reports coming to the Department, the swine pro-
ducers, county agents, and practicing veterinarians continue to be
faced with losses in young pigs caused by the parasitic worm
Strongyloides ransomi. This report concerns trials that were
carried out on a farm in central Florida where an outbreak of
strongyloides was considered the main cause of retarded growth and
deaths. Post-mortem and fecal examinations established S. ransomi
as the major cause of illness. The operation consisted of feeder-
pig production with 4 farrovings a year. The outbreak was confined
to one farrowing comprising about 40 pigs. According to the owner
the pigs farrowed just prior or after the outbreak were not serious-
ly affected. In fact, the pigs in the farrowing after the outbreak
were considerably heavier than the pigs of the affected farrowing,
though 3 months younger.

*Thiabendazole, experimental product, Lot 64 RTS 11, Merck, Sharp,
& Dohme Research Laboratories, Rahway, N.J.
**Dichlorvos, active ingredient in Atgard RV, a product of Shell
Chemical Company, New York, N.Y.
+Thiabendazole Paste, experimental product, Lot arck,
Sharp and Dohme Research Laboratories, kC yw .I 4 1


6/67:800





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-The purpose of these trials was: (1) to evaluate two new worm
remedies for removal of adult strongyloides under a farm condition;
(2) to determine if any weight advantage could be realized by treat-
ment of pigs already severely stunted by strongyloides infection
and (3) to evaluate treatment in suckling pigs of subsequent far-
rowings.

Experimental Procedure for Weanling Pigs:

Thirty-four pigs were available from the farrowing in which the
outbreak occurred. All pigs had been treated by the owner with
piperazine and were receiving hygromycin in the feed prior to being
placed on trial. These medications were not used during the trials.
Although all the pigs were within 4 days of the same age there was
considerable weight range (15 to 641bs. at 10 weeks of age). The
pigs were assigned to three groups of 11 or 12 pigs each on the basis
of pig size so that the groups were as nearly alike as possible.
Each group of pigs was kept in a sand lot of similar size, drainage,
and previous stocking.

At 10 weeks of age Group I pigs were untreated and served as con-
trols. Group II pigs were started on feed containing thiabendazole
at the rate of 1 lb./1,000 lbs. feed. Only the medicated feed was
available to these pigs for a two week period. Group III pigs
received a single feeding of dichlorvos at the recommended level
(median dosage 18mg/pound body weight). Body weights and fecal
samples for determining the number of strongyloid eggs per gram of
feces (epg) were taken from each pig at age 10 (pretreatment), 11,
13, 15 and 17 weeks. The Group I pigs served as untreated controls
until 15 weeks of age when they were treated with dichlorvos in the
same manner as Group III.

Results and Conclusions of Trial with Weanling Pigs The results
of the two worm remedies on the numbers of S. ransom eggs passed
in the feces are given in Table 1.

At 10 weeks of age the pretreatment average counts of the Groups
I, II, and III were similar (20,590; 21,264; and 20,480 epg). This
suggested the assignment of pigs resulted in three groups that were
similar in terms of infection.

At 11 weeks of age control Group I had an average count of 21,996
epg. The pigs of Group II, after one week of continuous thiabenda-
zole in the feed (0.1%), passed no eggs in the feces. The pigs of
Group III, one week after the single treatment with dichlorvos, were
passing an average of 9,654 epg or less than half the pretreatment
average.

The average strongyloid egg count of control Group I continued
to decrease naturally through the 13th week of age while Group II
remained negative and Group III increased slightly.






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"At 15 weeks of age pigs of control Group I averaged 11,274 epg,
Group II pigs were still negative, and the average of Group III
pigs was down to 3,540 epg. At this time the owner indicated that
a number of ascarids had been seen in the feces of the control group
but not in the other groups. This prompted the treatment of the
control group at this time with dichlorvos.

The final averages at 17 weeks of age were 460 epg in Group I,
0 in Group II, and 4,037 in Group III.

Within the conditions of this trial the 14 day feeding schedule
with 0.1% thiabendazole in the feed was highly effective in elim-
inating the eggs of S. ransomi from the feces of weanling pigs for
the entire seven week period of observation. The single feeding of
dichlorvos to Group III at 10 weeks of age resulted in a 52% reduc-
tion in the average epg from the pretreatment value in one week,
while the single feeding to Group I at 15 weeks of age resulted in
a 95% reduction in epg. The increased efficacy in the latter group
of older pigs may be due in part to natural loss of S. ransom
which is common for this age pig.

The average body weights of the pigs for the three groups are
presented in Table 2. The wide range of individual pig weights
made interpretation of results difficult, but in general it was con-
cluded that there was very little difference between groups. There
was no statistical difference in average body weight between Groups
I and II or Groups I and III at 15 and 17 weeks of age. Likewise,
there was no statistical difference in average daily gain between
Groups I and III.

The weights of the pigs in Groups I and II were undoubtedly in-
fluenced by ascarid infection. During the trial period no treat-
ment for ascarids was instituted in Group II and only at 15 weeks
of age in Group I. Dichlorvos is effective in removing ascarids.

It was therefore concluded that although treatment was of definite
value in reducing the contamination of the premises, no weight ad-
vantage was observed when treatment was administered to pigs already
clinically ill or stunted from infection with S. ransomi. To
maintain normal weight gains treatment must be instituted prior to
severe clinical signs of parasitism.

Experimental Procedure for Suckling Pigs Two litters of suckling
pigs from the second farrowing following the outbreak were selected
to evaluate a treatment schedule.

One litter received 200mg/pig of a paste formulation of thiabenda-
zole orally at 11 days of age. At 25 days of age a medicated feed
containing o.1% thiabendazole was creep fed for 14 days. During the
period on medicated feed the pigs also had access to sow's milk
and the unmedicated sow's feed.





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"A second litter was retained as an untreated control group.

Body weights and epg of feces were determined for these two
litters over a 4 week period.

An indirect influence on these litters existed since all other
litters of this farrowing were provided with o.1% thiabendazole in
the feed at about 4 weeks of age. Thus, the level of contamination
on the farm, in general, was surpressed.

Results and Conclusions of Trial with Suckling Pigs The results of
the treatment schedule on average epg of feces are given in Table 3.

At 11 days of age, average pretreatment counts suggested Litter
T pigs possessed a heavier infection than Litter C (391,000 and
133,500 epg respectively, or nearly 3 times as great).

At 18 days of age the pigs of control Litter C showed an increase
in average epg of feces while Litter T pigs 1 week after treatment
showed a 95% reduction (from 391,000 to 19,524 epg).

At 25 days of age, the average epg of Litter C dropped 86% from
the prior week. This suggested a natural loss of worms. The average
epg of Litter T dropped only slightly.

At 39 days of age, Litter C had dropped to 9,600 epg while the
pigs of Litter T after the 2 week period on medicated feed averaged
776 epg. Although the average epg count of treated Litter T was
only 8% of untreated Litter C, tests conducted elsewhere have con-
sistantly resulted in complete clearance of adult S. ransomi from
pigs fed o.1% thiabendazole in the feed for 14 days. The litters on
trial here, however, had access to sow's milk and unmedicated sow's
feed which resulted in a reduced consumption of medicated feed.

The average body weights of the pigs in the two litters were not
statistically different at age 39 days. However, the pigs in treated
Litter T initially had an average epg count nearly three times as
great as the controls and presumably a greater level of infection.
Yet their average weight at age 39 days was slightly greater than
the untreated controls. Thus, their weights in the absence of the
treatment might have been considerably less.

Two pigs from Litter T died during the 4 week observation period
from causes determined primarily as other than from S. ransomi.
Worm recoveries from these two pigs were 0 and 500 aEult worms.

Nearly all pigs of the farrowing experienced a 1 week period of
diarrhea at 2 to 3 weeks of age which was not solely attributable
to S. ransomi and was presumed to be the colibacillosis sydrome.





Table 1.


The Influence of 0.1% Thiabeudazole in the feed (TBZ/F) or Dichlorvos
(AtgardR V) on Strongyloid Eggs Per Gram of Feces (epg) in Weanling
Pigs Recovering from Severe Infection with Strongyloides ransomi.


Pigs Age 10 Weeks Age 11 Weeks Age 12 Weeks Age 13 Weeks Age 15 Weeks Age 17 Weeks
Group Per Av. epg Treat- Av. epg Treat- Treat- Av epg Treat- Av epg Treat- Av epg Treat-
Group ment ment ment ment ment ment


I 11 20,590 None 21,996 None None 18,717 None 11,274 Dichl- 460 None
orvos
II 12 21,264 TBZF 0 TBZ/F TBZ/F 0 None 0 None 0 None

III 11 20,480 Dichl- 9,654 None None 10,159 None 3,540 None 4,037 None
orvos





Table 2. The InfAuence of 0.1% Thiabendazole in the feed (TBZ/F) or Dichlorvos
(Atgard V) on Body Weight (Pounds) of Weanling Pigs Recovering from
Severe Infection with Strongyloides ransomi.

Pigs Age 10 Weeks Age 11 Weeks Age 12 Weeks Age 13 Weeks Age 15 Weeks Age 17 Weeks
Group Per
Group Av. Treat- Av. Wt. Treat- Treat- Av. Wt. Treat- Av. Wt. Treat- Av. _Treat Il Totl
Initial ment ment ment ment ment Final meant a Av.
Wt. Wt. Gain Gain

I 11 37.4 None 41.6 None None 48.5 None 58.2 Dichl- 66.5 None 0.59 29.1
orvos
II 12 34.9 Start On Off
T 12 34.9 F 39.2 B/F TB 48.3 None 59.1 None 66.9 None 0.65 32,0

II 11 34.7 Dichl- 39.3 None None 47.5 None 59.6 None 69.0 None 0.70 34.3
orvos





Table 3. The Influence of a Treatment Schedule Consisting of Thiabendazole
(200/pig orally) Plus 0.1% Thiabendazole in the Feed (TBZ/F) on
Strongyloid Eggs Per Gram of Feces in Suckling Pigs.


Pigs Age 11 Days Age 18 Days Age 25 Days Age 39 Days
Litter Per Pretreatment Treatment Av. epg Av. epg Treatment Av. epg Treatment
Av. epg


C 10 133,500 None 140,800 19,340 None 9,600 None

T 10 391,000 TBZ 19,524 18,438 TBZ/F 776 OFF
Orally On TBZ/F







Table 4. The Influence of a Treatment Schedule Consisting of Thiabendazole
(200 mg/pig orally) Plus 0.1% Thiabendazole in the Feed (TBZ/F) on
Body Weight (Pounds) in Suckling Pigs.

Pigs Age 11 Days Age 18 Days Age 25 Days Age 39 Days
Litter Per Pretreatment Treatment Av. Wt. Av. Treatment Av. Treatment Total Total
Litter Av. Wt. Wt. Wt A Av.
Daily Gain
Gain

C 10 -None 8.7 10.5 None 17.8 None 0.42 9.1

T 10 -TBZ 8.1 10.3 On 17.9 Off 0.49 9.8
Orally TBZ/F TBZ/F




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