# CL Treatments



## Caprine Beings

RUMINANTS

Comparison of three treatment regimens
for sheep and goats with caseous lymphadenitis

Kevin E. Washburn, dvm, dacvim, dabvp; Wesley T. Bissett, dvm, phd; Virginia R. Fajt, dvm, phd, dacvcp; 
Melissa C. Libal, dvm, ma, dacvm; Geoffrey T. Fosgate, dvm, phd, dacvpm; Joseph A. Miga; Kristine M. Rockey

Objective-To compare the effectiveness of 3 treatment regimens for small ruminants with 
caseous lymphadenitis. 
Design-Randomized clinical trial.

Animals-44 client-owned sheep and goats. 
Procedures-Aspirates were obtained from 48 lesions of 44 enrolled animals and submitted 
for bacterial culture. Animals were randomly assigned to 1 of 3 treatment groups.Treatment 
for group A (n = 15 lesions) consisted of opening, draining, and flushing the lesions 
and SC administration of procaine penicillin G. Treatment for group B (n = 15 lesions) consisted 
of closed-system lavage and intralesional administration of tulathromycin. Treatment 
for group C (n = 18 lesions) consisted of closed-system lavage and SC administration of 
tulathromycin. All animals were reexamined approximately 1 month after treatment, unless 
treatment failure was detected prior to that time.

Results-43 animals with lesions had positive results (Corynebacterium pseudotuberculosis) 
for bacterial culture. Proportions of lesions that had resolution of infection by 1 month 
after treatment did not differ significantly among the treatment groups (group A, 13/14 
[92.9%]; 95% confidence interval [CI], 69.5% to 99.6%; group B, 10/12 [83.3%]; 95% CI, 
54.9% to 97.1%; and group C, 14/17 [82.4%]; 95% CI, 59.1% to 95.3%).

Conclusions and Clinical Relevance-Acceptable alternatives to opening, draining, and 
flushing of lesions may exist for treatment of sheep and goats with caseous lymphadenitis. 
Use of tulathromycin and penicillin in this study constituted extralabel drug use, which 
would require extended withholding times before milk or meat of treated sheep and goats 
can be sold for human consumption. (J Am Vet Med Assoc 2009;234:1162-1166)

Caseous lymphadenitis is a chronic, suppurative disease 
caused by Corynebacterium pseudotuberculosis.
Sheep, goats, horses, cattle, and humans can be affected 
by this disease. Caseous lymphadenitis is currently of 
most interest in small ruminants and is implicated as the 
third leading cause of economic loss to the sheep industry 
in the western United States.1 In 1 report2 in which 
investigators examined samples from culled sheep from 
regions representing 9 western states, the prevalence was 
estimated as 42.41%. Although prevalence studies for 
goats in the United States are lacking, there is an ever-
increasing number of goats3 and caseous lymphadenitis 
should be an important health consideration.

The characteristic lesions of caseous lymphadenitis 
are single or multiple abscesses of the lymph nodes, 
skin, and viscera.4 The causative organism enters the 
body through broken or intact skin, via inhalation, or 
across mucous membranes. Inside the host, the organism 
spreads via the lymphatics to lymph nodes and internal 
organs, where abscesses develop during a period 
of 2 to 6 months. Bacteria are released into the environment 
through discharge from draining superficial

From the Departments of Large Animal Clinical Sciences (Washburn, 
Bissett), Veterinary Physiology and Pharmacology (Fajt), Veterinary 
Pathobiology (Libal), and Veterinary Integrative Biosciences 
(Fosgate), College of Veterinary Medicine and Biomedical Sciences 
(Miga, Rockey), Texas A&M University, College Station, TX 77843.

Supported by the American Boer Goat Association.

Address correspondence to Dr. Washburn.

Abbreviation

CI Confidence interval

abscesses or are aerosolized from ruptured abscesses in 
the lungs.5

Treatment and control modalities for caseouslymphadenitis include lancing of abscesses and flushing 
with potentiated iodine solutions, treatment with 
antimicrobials, culling of affected animals, surgical removal 
of abscesses, intralesional injection of formalin, 
and isolation from other animals to prevent disease 
spread.6 Lancing and flushing abscesses create a potential 
hazard for spread of purulent material to fomites 
and into the environment during the convalescent period. 
Although antibacterial protocols have been used 
for pharmacologic treatment of animals with caseous 
lymphadenitis,5,7 acceptable efficacy has not been determined 
because the abscesses typically are thickly encapsulated, 
which hinders penetration of antimicrobials.8Additionally, because of the organism's intracellular location, 
some antimicrobials may not reach efficacious 
intracellular concentrations. At best, clinicians canhope for a reduction in size of the abscess and nonrecurrence 
of the condition. At worst, the abscesses can 
rupture and drain, which spreads organisms into the 
environment and could potentially infect others in the 
herd. Culling of genetically superior animals is often 
not a desirable or economically feasible option; howev

1162 Scientific Reports JAVMA, Vol 234, No. 9, May 1, 2009

er, retaining these animals in the herd greatly increases 
the risk of transmission. Although curative in the short 
term, surgical resection of abscesses does not address 
recurrence, requires local or general anesthesia, and is 
a more expensive option than the other reported treatment 
alternatives. Injection of formalin into the lesions 
reportedly is beneficial9; however, a carcass containing 
formalin would be considered adulterated and would 
be unfit for human consumption. The potential for negative 
public perception related to this practice is also a 
problem.

Tulathromycin, a newly introduced triamilide 
antimicrobial, is a member of a subclass of the macrolide 
family labeled for treatment of cattle and swine 
with undifferentiated respiratory tract disease. It is 
highly lipid soluble and, in cattle, maintains concentrations 
in lung tissue greater than the minimum inhibitory 
concentration (2.0 µg/mL) for the primary 
respiratory pathogens for at least 7 days.10 The long-
lasting properties and high degree of lipid solubility 
may allow this drug to enter encapsulated abscesses 
and achieve adequate intracellular concentrations.

The safety of tulathromycin used in an extralabel 
manner was investigated in another study11 conductedby our laboratory group. In that study,11 tulathromycin 
was administered at 25 mg/kg (11.4 mg/lb; 10 times the 
label dosage) to goats to investigate deleterious effects. 
No short-term adverse effects were detected in that 
study. To our knowledge, there have been no reported 
pharmacokinetic studies conducted in sheep or goats.

The objective of the study reported here was to 
compare the effectiveness of treatments for small ruminants 
with caseous lymphadenitis. Specifically, we 
evaluated the use of opening, flushing, and draining of 
lesions followed by penicillin administration, closed-
system lavage and intralesional administration of tulathromycin, 
and closed-system lavage and parenteral 
administration of tulathromycin.

Materials and Methods

Sample population-Client-owned sheep and goats 
were used in the study. The criterion for enrollment in 
the study was that an animal had a solitary subcutaneous 
mass consistent with an abscess. The same animal could 
be enrolled more than once during the study period when 
a lesion resolved within 1 month after initial treatment 
and a new lesion developed in another location. A case 
was defined as an enrolled study subject whose lesion 
yielded positive results when cultured for C pseudotuberculosis. 
A study subject could also contribute > 1 case 
during the study period when a new lesion developed 
in another location and when that lesion also had positive 
results for culture of C pseudotuberculosis. Owners 
were required to sign a consent form prior to enrollment 
of their animals. The consent form and study were approved 
by the Texas A&M University Clinical Research 
Review Committee.

Data obtained for all enrolled animals included 
age, sex, breed, number of days the lesion was evident 
(ie, detected by the owners) prior to initial examination 
by the authors, caseous lymphadenitis vaccination status, 
history of caseous lymphadenitis on the farm, and 
recent antimicrobial treatments. Physical examinations

were performed, and the lesions were described as firm 
or fluctuant, hair or no hair, and draining or not draining. 
All lesions were photographed, and the location of 
each lesion was recorded.

Isolation and identification of C pseudotuberculosis-
For all sheep and goats enrolled in the study, each lesion 
was aseptically prepared by clipping the hair from around 
the lesion, scrubbing the area with betadine solution, and 
rinsing with isopropyl alcohol. Each lesion was then aspirated 
with a 16-gauge, 3-cm needle to obtain material for 
bacterial culture. Samples were inoculated onto 5% sheep 
blood agara and MacConkey agara and into tryptose broth. 
The blood agar and tryptose broth were incubated at 37°C 
in 5% carbon dioxide for up to 72 hours. After incubation 
for 24 to 48 hours, tryptose broth was subcultured to 5% 
sheep blood agar and incubated at 37°C in 5% carbon dioxide 
for an additional 24 to 48 hours (total incubation of 72 
hours). Plates containing MacConkey agar were incubated 
at 37°C in air for up to 72 hours. Suspect colonies were subcultured 
for purity and confirmed to be C pseudotuberculosis 
by useofa Corynebacterium identification system.b

Serum hemolysin-inhibition test-Blood samples 
were obtained from all sheep and goats prior to 
treatment. Blood samples were collected via jugular 
venipuncture and used for serologic testing to determine 
serum hemolysin-inhibition titers. Briefly, 
the hemolysin inhibition titer was determined by the 
synergistic action of Rhodococcus equi and C pseudotuberculosis 
toxins. Establishing the point at which hemolysis 
was inhibited was performed on a blood agar 
plate. Serum samples were placed in 8 wells cut into 
the plate, which contained 8 different serial dilutions 
of hemolytic units.c

Treatment groups-Sheep and goats were randomly 
assigned to 1 of 3 treatment groups by use of 
a block design. For treatment group A, lesions were 
opened at their most ventral aspect by use of a No. 21 
scalpel blade. An elliptic incision was made to remove 
skin and provide a sufficient opening for drainage. The 
cavity was drained and flushed thoroughly with diluted 
betadine solution. A single dose of procaine penicillin 
G (20,000 U/kg [9,091 U/lb], SC) was administered in 
the neck region. For treatment group B, lesions were 
pierced with a 16-gauge, 3-cm needle and filled with 
saline (0.9% NaCl) solution to break up purulent material. 
The abscess cavity was then treated with distention 
lavage, with saline solution used to remove purulent 
material. A single dose of tulathromycin (2.5 mg/kg

[1.14 mg/lb]) was injected into the empty abscess cavity 
(ie, intralesional administration). For treatment group 
C, lesions were lavaged with saline solution (similar 
to the procedure for group B) and a single dose of tulathromycin 
(2.5 mg/kg, SC) was administered in the 
neck region. All sheep and goats were scheduled for a 
reexamination at 1 month after treatment.

Discharge instructions-Sheep and goats were discharged 
to their owners. Discharge instructions included 
information on the withholding period for animals 
because of the extralabel use of tulathromycin (45 days 
for milk and 36 days for meat) and penicillin (5 days 
for milk and 10 days for meat), as recommended by

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the Food Animal Residue Avoidance Databank.12 Owners 
were also informed that they would be contacted by 
telephone approximately 1 month after the initial treatment 
to obtain additional information. Finally, owners 
were provided with information regarding biosecurity 
and criteria that constituted treatment failure and 
would necessitate reexamination prior to the scheduled 
1-month reexamination.

Treatment failure was defined as any sheep or goat 
whose lesion enlarged to pretreatment size or larger 
within 10 days after treatment. For case animals in 
groups B and C, treatment failure also included rupture 
and draining of the lesion. Owners were instructed 
that if there was such a treatment failure prior to the 
scheduled 1-month reexamination, they were to return 
the animal to the veterinarian that enrolled it into the 
study.

Follow-up telephone call-Approximately 1month after initial treatment, owners were contacted by 
telephone by an interviewer who was not aware of treatment 
group assignment. Information gathered included 
whether the lesion had resolved and, if not, whether the 
lesion was larger, smaller, or had ruptured and drained. 
The interviewer also recorded when a new lesion had 
appeared in another location and whether the animal 
had any adverse effects, such as anorexia or lethargy. 
During the telephone conversation, the appointment 
was scheduled for the 1-month reexamination.

Follow-up examination-Approximately 1-month 
after initial treatment, all sheep and goats enrolled in 
the study were reexamined. At that time, a lesion was 
considered unresolved when it was still evident in the 
same location as that of the initial examination and was 
the same size, larger, or only slightly reduced in size 
(= 
75% of the original size). Unresolved lesions were 
aseptically prepared, and material was aspirated for 
bacterial culture. Unresolved lesions were opened,
drained, and flushed in accordance with the protocol 
established for group A animals. Although these lesions 
were considered unresolved for their originally 
assigned treatment groups, another follow-up examination 
performed approximately 1 month after the second 
treatment was used to ensure resolution of lesions.

Statistical analysis-Data were summarized for 
the 3 treatment groups by use of descriptive statistics. 
The Kruskal-Wallis 1-way ANOVA was used to compare 
medians of quantitative data. Categoric variables 
were compared among the 3 treatment groups and on 
the basis of lesion characteristics by use of . 
2 tests and 
Fisher exact tests for pairwise comparisons. Treatment 
effects were evaluated by estimating risk ratios (comparing 
the proportion of treatment successes withineach group) and their corresponding 95% CIs. Sensitivity 
and specificity of the serum hemolysin-inhibition 
test were estimated as the proportion of culture-positive 
and culture-negative animals, respectively, correctly 
identified by the serologic test. Confidence intervals 
were calculated for all proportions, and categoric analyses 
were performed with available software.d Analysesof quantitative variables were performed with another 
program.e All analyses were considered significant at 
values of P < 0.05.

Results

Sample population-During approximately 12months, 44 animals (41 goats and 3 sheep) with 48 lesions 
were enrolled in the study. Two goats each represented 
2 cases and 1 goat represented 3 cases because 
they developed lesions in other locations > 1 month 
apart. Eighteen farms from 2 states were represented; 
12 farms each provided > 1 enrolled animal. Fifteen enrolled 
cases were assigned to group A, 15 were assigned 
to group B, and 18 were assigned to group C.

Animals ranged from 6 to 96 months of age. Ten 
were male and 34 were female. Goat breeds represented 
included Boer (n = 33 goats), La Mancha (3), Nubian 
(2), and mixed-breed goats (3). The 3 sheep were of 
the Suffolk breed. The number of days that the lesion 
was evident (detected by the owners) prior to initial examination 
by the authors ranged from 1 to 100. Seven 
goats had been vaccinatedf against caseous lymphadenitis; 
vaccinations were administered from 6 months to 
1 year before initial examination by the authors. Thirty-
five sheep and goats originated from farms with a history 
of caseous lymphadenitis. None of the animals had 
received antimicrobial treatment prior to enrollment in 
the study. Signalment and history of caseous lymphadenitis 
did not differ significantly among treatment 
groups (Table 1).

Initial physical examination of lesions revealed that 
26 were firm and 21 were fluctuant. Thirty-eight lesions 
were covered with hair, and 9 were considered to have 
no hair. Six lesions were draining, and 41 lesions were 
not draining. Physical examination information wasnot available for 1 lesion in a goat. Lavage of the firm 
(ie, nonfluctuant) lesions was not as rewarding for the 
removal of purulent material, compared with removal 
of purulent material in fluctuant lesions, and the typical 
volume of material aspirated and removed from the 
lesions varied widely on the basis of size and maturity 
of the lesions.

Culture results-Corynebacterium pseudotuberculosis 
was isolated from 43 lesions. Bacteria isolated 
from the remaining 5 lesions included Arcanobacterium 
pyogenes, coagulase-negative Staphylococcus spp, a-hemolytic 
Streptococcus spp, Pseudomonas spp, and Enterococcus 
spp.

Results for treatment groups-Of the 43 lesions 
that yielded C pseudotuberculosis on bacterial culture, 
14 were assigned to group A, 12 were assigned to group 
B, and 17 were assigned to group C. Examination findings 
of lesions for the 43 culture-positive cases prior to 
treatment did not differ significantly among treatment 
groups (Table 2). No adverse effects were recorded for 
any sheep or goat during the study period. Additionally, 
there were no treatment failures recorded by the owners. 
All 5 lesions that had negative results when cultured 
for C pseudotuberculosis were considered resolved 
at the 1-month reexamination, whereas 37 of 43 (86%) 
culture-positive lesions were considered resolved. Of 
the 6 unresolved cases at the 1-month reexamination, 
1 had been assigned to group A, 2 to group B, and 3 to 
group C. The proportions of resolution at the 1-month 
reexamination for the 43 C pseudotuberculosis-positivelesions were 92.9% (95% CI, 69.5% to 99.6%), 83.3%

1164 Scientific Reports JAVMA, Vol 234, No. 9, May 1, 2009

Table 1-Comparisons of quantitative and proportions for categoric variables of sheep and goats with 
caseous lymphadenitis.

Treatment group*

P value†

Variable A(n=15) B(n=15) C(n=18)

Overall A vs B and C

SexFemale (No.) 13 11 12 0.411 0.292 
Male (No.) 2 4 6

BreedBoer goat (No.) 12 10 15 0.499 1.000 
Other goat (No.) 3 3 2 0.726 1.000 
Sheep (No.) 0 2 1 0.317 0.542

Vaccinated againstcaseouslymphadenitis (No.)

Yes 2 3 2 0.761 1.000 
No 
1312 16

History of caseouslymphadenitis onfarm (No.)

Yes 12 11 12 0.691 0.727

No 
346 
Age (mo)‡ 16 (8-60) 24 (8-48) 24 (6-96) 0.689 0.398 
No. of days lesion 7 (1-100) 7 (1-30) 10 (4-60) 0.294 0.473

noticed prior to
initial examination‡

*Treatments were as follows: group A, opening, flushing, and draining of lesion followed by SC administration 
of penicillin; group B, closed-system lavage and intralesional administration of tulathromycin; and group 
C, closed-system lavage and parenteral administration of tulathromycin. †P values for categoric variables 
based on comparison of proportions for the variable (eg, female vs male and Boer vs all others) across treatment 
groups. Values were considered significant at P . 0.05. ‡Value reported is median (range).

n = Number of lesions; there were 48 lesions for 44 sheep and goats enrolled in the study.

Table 2-Number of findings in sheep and goats with caseous 
lymphadenitis whose lesions yielded Corynebacterium 
pseudotuberculosis during bacterial culture performed prior to 
treatment.

Treatment group* P value†

Variable A(n=14) B(n=11)‡ C(n=17) Overall AvsBandC

Fluctuant 4 5 9 0.386 0.186 
Firm 10 5 8 
No hair 3 4 2 0.301 1.000 
Hair 11 6 15 
Draining 2 2 2 0.894 1.000 
Not draining 12 8 15

‡Missing information from 1 animal.
See Table 1 for remainder of key. 
(95% CI, 54.9% to 97.1%), and 82.4% (59.1% to 95.3%) 
for groups A, B, and C, respectively; these values did 
not differ significantly (P = 0.668) among treatment 
groups. Resolution of lesions did not differ significantly 
on the basis of lesion characteristics for firm (83%) versus 
fluctuant (89%; P = 0.673), hair (85%) versus no 
hair (89%; P = 1.00), or draining (100%) versus not 
draining (83%; P = 0.569).

Each of the 2 farms that enrolled the most animals 
had at least 1 animal that provided multiple cases. One 
buck from the farm with the highest number of animals 
enrolled was treated 3 times during a 10-month period 
(defined as 3 cases for that goat). Initially, this goat was 
assigned to group C, and the lesion was considered unresolved 
at the 1-month reexamination. At that time, the 
lesion was treated in accordance with the protocol for 
group A, and it subsequently resolved 1 month later. Five 
and 10 months after initial enrollment, the buck devel

oped lesions in new locations. It was assigned to groups A 
and C, respectively, and for both of those treatments, lesions 
were considered resolved by the 1-month reexamination. 
The farm with the second highest number of enrolled 
animals had 2 does with lesions that were considered resolved 
at 1 month and that subsequently developed new 
lesions 8 months after initial treatment. Both of these 
does were assigned to group A for the original lesions, 
but both were assigned to group C for the lesions that 
subsequently developed in new locations.

Serum hemolysin-inhibition test-Antibody titers 
against C pseudotuberculosis (as determined by use of the 
serum hemolysin-inhibition test) at initial examination 
ranged from 0 to 1:64. Of the 43 culture-positive lesions, 
35 were in seropositive animals, with titers that ranged 
from 1:4 to 1:64, whereas 8 were in seronegative animals. 
Sensitivity for the serum hemolysin-inhibition test 
was 81% (95% CI, 68% to 91%). For the 5 culture-negative 
lesions, 3 were in seropositive animals and 2 were in 
seronegative animals. Specificity for the serum hemolysin-
inhibition test was 40% (95% CI, 7% to 82%). Of the 
7 animals vaccinated against caseous lymphadenitis, 6 
were seropositive (titers ranged from 1:4 to 1:64); 2 of the 
6 were culture-negative animals. The remaining vaccinate 
was a culture-positive animal that was seronegative.

Discussion

Animals enrolled in the study reported here were 
predominately Boer goats. This breed represents most 
of the goats examined at our hospital. Additionally, this 
study investigated only 1 form of caseous lymphadenitis. 
Diagnostics were not performed to determine whether

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JAVMA, Vol 234, No. 9, May 1, 2009 Scientific Reports 1165

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any enrolled animals had visceral or internal lymph node 
involvement. However, those manifestations of caseous 
lymphadenitis are most often accompanied by a history 
of chronic weight loss, and none of the animals in this 
study had that history. Despite these limitations, it appears 
from our data that intralesional or parenteral treatment 
with tulathromycin after removal of purulent material via 
needle distention lavage may be an acceptable alternative 
to opening, draining, and flushing caseous lymphadenitis 
abscesses coupled with penicillin administration.

However, the small number of cases in each treatment 
group in this study did not provide the power necessary 
to make conclusive statements of efficacy. Additional 
studies are needed to accurately determine the benefit of 
various protocols for resolution of caseous lymphadenitis. 
Although not significantly different, lesions treated in accordance 
with the protocol for group A had a higher proportion 
of resolution than for groups B and C combined. 
Because of its spectrum of activity against gram-positive 
organisms, administration of penicillin to goats of group 
A could have contributed to the higher proportion of lesions 
that resolved. However, we believe that the benefits 
of not opening these lesions and avoiding spread of bacteria 
into the environment during the convalescent period 
outweighed the small differences in outcome among these 
groups. Thus, we believe that the higher proportion for 
resolution in group A is not clinically important.

Interestingly, the sensitivity of the serum hemolysin- 
inhibition test at initial examination was lower than that 
reported for animals with naturally developing infections, 
whereas the specificity was higher.13 False-negative results 
could have been attributable to the enrollment of animals 
with chronic, well-encapsulated abscesses that may have 
had low circulating antibody titers. False-positive results 
in this study could have been attributable to internal abscesses 
or exposure of animals to the organism, especially 
on farms that contributed multiple cases and that had limited 
biosecurity prior to participation in our study. Also, 2 
animals were vaccinated and were seropositive, but their 
lesions did not yield C pseudotuberculosis isolates.

Although no treatment failures were reported by the 
owners, it is possible that lesions opened and drained in 
such a manner that they were not noticed by the owners. 
Nevertheless, there was only 1 new animal that developed a 
lesion among all 18 farms represented during the approximately 
12-month study period, which indicated that once 
affected animals within a herd were identified, enrolled, and 
treated, there was no widespread increase in disease incidence. 
This suggested that biosecurity measures on those 
farms were excellent or lesions that resolved did so in an innocuous 
manner. Similarities in outcome among treatment 
groups could have been attributable to many factors, most 
notably the number of days the lesion was evident before 
initial examination. Additionally, the stage of the lesion at 
initial treatment may have affected outcome. Lesions that 
were draining at the time of initial examination would have 
been more representative of animals in group A (without 
the betadine flush); therefore, draining lesions assigned to 
groups B (n = 2 cases) and C (2) may have resolved because 
they were open and not because of intralesional or parenteral 
administration of tulathromycin.

It is possible that the physical removal of purulent material 
via lesion distention lavage with saline solution, as 
performed in groups B and C, may have positively influenced 
outcome in these groups. A control group in which

lesions were emptied by intralesional lavage but were not 
treated by administration of tulathromycin may have been 
an informative addition to the study; however, the willingness 
of clients to participate may have been compromised.

To our knowledge, minimum inhibitory concentrations 
of tulathromycin against C pseudotuberculosis isolates 
in small ruminants are lacking, as are pharmacokinetic data 
for tulathromycin in goats. Such studies are warranted to 
determine more precisely the pharmacodynamics of tulathromycin 
when used to treat animals with caseous lymphadenitis. 
Other antimicrobials injected intralesionally may also 
be efficacious and should be examined in future studies.

Overall, it appears that intralesional or parenteral 
administration of tulathromycin may be an acceptable 
alternative to opening, draining, and flushing of caseous 
lymphadenitis lesions. More affected animals from diverse 
geographic areas and longer follow-up periods are needed 
in future studies to investigate the effects of tulathromycin 
treatment for animals with caseous lymphadenitis on the 
management of this disease in goat herds. Additionally, efficacy 
of this treatment for other manifestations of caseous 
lymphadenitis remains to be investigated.

a. 
BBL, BVA Inc, San Antonio, Tex. 
b. 
API Corynebacterium identification system, BioMerieux Inc, Hazel-
wood, Mo. 
c. 
Standard operating procedures, No. 0078, Texas Veterinary Medical 
Diagnostic Laboratory, College Station, Tex. 
d. 
Epi Info, version 6.04, CDC, Atlanta, Ga.
e. 
SPSS for Windows, version 15.0, SPSS Inc, Chicago, Ill. 
f. 
Case-Bac, Colorado Serum Co, Denver, Colo. 
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