Testicular atrophy in Columbian black-tailed deer in California

Abstract

During an 18-year period, 4.1% (34/831) of male deer (Odocoileus hemionus columbianus) killed on a field station during the autumn hunting season had velvet-covered, often misshapen antlers, and at least two deer had testicular atrophy (gonads from most deer were not available for examination). Testes from six similarly affected deer and several normal deer were compared histologically. Lesions ranged from hypocellularity of the semeniferous tubules and relative hyperplasia or degeneration of interstitial cells to complete connective tissue replacement of the testicular parencyma. Chronic vascular changes were present in several testes. The etiology and pathogenesis of the lesions were not determined.

Full text

Journal of Wildlife Diseases Vol. 11, January, 1975 101
TESTICULAR ATROPHY IN COLUMBIAN BLACK-TAILED DEER
IN CALIFORNIA
JAMES C. DeMARTINI, Wild Animal Disease Center and Department of Pathology,
College of Veterinary Medicine and Biomedical Sciences, Colorado State University,
Fort Collins, Colorado, 80523, U.S.A.
GUY E. CONNOLLY, Hopland Field Station, University of California,
Hopland, California, 95449, U.S.A.
Abstract: During an 18-year period, 4.1% (34/83 b) of male deer (Odocoi/eus hemi-
onus co/umbianus) killed on a field station during the autumn hunting season had
velvet-covered, often misshapen antlers, and at least two deer had testicular atrophy
(gonads from most deer were not available for examination). Testes from six simi-
larly affected deer and several normal deer were compared histologically. Lesions
ranged from hypocellularity of the semeniferous tubules and relative hyperplasia or
degeneration of interstitial cells to complete connective tissue replacement of the
testicular parenchyma. Chronic vascular changes were present in several testes. The
etiology and pathogenesis of the lesions were not determined.
INTRODUCTION
Testicular atrophy, usually associated
with antler anomalies, has been described
in white-tailed deer in Texas”’#{176}and in
a mule deer in Colorado.6 The antler
anomalies consist of abnormal confor-
mation and retention of the velvet, a
specialized skin which covers the antlers
during their growth. The velvet is nor-
mally desquamated by the autumn period
of heightened sexual activity. The re-
lationship between antler growth, de-
velopment, and shedding and testosterone
levels has been described.”
The testicular lesions have been char-
acterized as tubular atrophy with asper-
matogenesis and a decrease7 or hyper-
plasia’ of interstitial cells. Focal eosino-
philia and plasma cell infiltration were
reported in one case, although the etio-
logy of the condition was not discovered.6
Three cases of testicular hypoplasia
were characterized by lack of develop-
ment of seminiferous epithelium and
prominence of interstitial cells.’ Abnor-
malities of the antlers were not present
in these cases.
MATERIALS AND METHODS
Cases included in this report were all
part of the resident deer population on
the 1200 ha University of California
field station at Hopland in the north
coastal region of California. Between
b9SS and 1973, records were kept of the
numbers and condition of bucks taken
each autumn during the hunting season.
Testes from two bucks killed by hunters
and four other bucks with velvet-covered,
misshapen antlers were examined grossly
and fixed in buffered neutral formalin
or formol-Zenker’s solution, sectioned at
6 m, and stained with hematoxylin and
eosin, Periodic acid-Schiff’s (PAS), oil-
red-O, or Perl’s iron techniques. One
animal was necropsied. For comparative
purposes, testes were also collected from
immature and adult normal bucks dur-
ing various seasons of the year.
Clinical History
Between 1955 and 1973, 34/831
(4.1%) of the bucks killed in August
and September of each year by hunters
on the Hopland field station had velvet-

‘a.
41
FIGURE 1. Testis from normal deer taken during the spring period of sexual inactivity. Semi-
niferous tubules are small and relatively hypocellular. H&E, X250.
102 Journal of Wildlife Diseases Vol. 11, January, 1975
covered antlers, which were often mis-
shapen with spurious points. Velvet is
normally shed from the antlers during
late July or early August in this area.
The mean number of affected animals
each year was 1.8 (range 0-4) while the
mean number of bucks taken on the sta-
tion each year was 47 (range 17-63).
Five captive bucks on the field station
developed the same condition, and sev-
eral of these were known to have been
normal until 2 to 4 years of age, when
the syndrome first appeared. Most of the
affected animals lacked secondary sex
characteristics, such as a thick neck, and
one deer had prominent teat develop-
ment. Generally, the deer were normal
in weight and body condition, although
one had an abscess of a jaw and another
had otitis externa.
The owner of a ranch about 11 km
from the field station reported that only
two “stags” (deer with misshapen velvet-
covered antlers) were seen during the 30
years prior to 1967, when a large wild-
fire occurred on the ranch. Between 1968
and 1972, about one third to one-half of
the bucks killed each year (about 20)
had been “stags”. The fire had been
controlled by aerial tankers using retar-
dants (Firetrole 100, Arizona Agro-
chemical Corporation, P.O. Box 2b91,
Phoenix, Arizona 85001; and Phos-check
202, Monsanto Company, 6670 East
Flotilla Street, Los Angeles, California
90022). Following the fire, 152 ha were
seeded with a mixture of harding grass,
milo, pubescent wheat grass, blando
bromegrass, and perennial ryegrass at
1.8 kg/ha. To control brush, the area
was sprayed by air at 47 1/ha the fol-
lowing spring with a mixture of 4.4 kg
of 2,4-D, 2.2 kg of 2,4,5-T, and 1.9 1 of
diesel oil diluted with water to 19 1.

Journal of Wildlife Diseases Vol. 11, January, 1975 103
FIGURE 2. Testis from normal deer taken during the fall “rut”. Seminiferous tubules are
enlarged, and there is active spermatogenesis. H&E, X250.
Gross Findings
Compared with testes removed from
normal bucks killed at the same time of
the year (20-35 g each), testes from all
velvet-antlered deer were bilaterally mar-
kedly diminished in weight (2-6 g each).
The testicular parenchyma of these ani-
mals was much reduced in size in rela-
tion to the epididymis. The parenchyma
of affected testes was quite firm and
yellow-brown on cut surface.
Comp’eted necropsy examination of
one velvet-antlered buck failed to reveal
additional significant gross or microsco-
pic lesions in organs other than the
gonads.
Histopathology
The most prominent histological fea-
ture of atrophic testes was the decrease
in size and number of seminiferous tu-
bules with loss of spermatogonia and
spermatocytes. Tubules were of variable
size. often containing only sertoli cells
and were usually surrounded by thick-
ened PAS-positive basement membranes.
Occasionally, tubules contained calcified
debris. In two animals there was com-
plete connective tissue replacement of
the testicular parenchyma with no rem-
nants of tubules or interstitial cells. A
testis of another animal had an organiz-
ing infarct. Very few inflammatory cells
were present in most testes, although oc-
casional mononuclear cells contained
PAS-positive brown granular pigment
(lipofuscin) and rare macrophages con-
taining iron-positive golden granular pig-
ment (hemosiderin) were observed.
The epididymes of the atrophic testes
were inevitably aspermic. The lumens of
the tubules were usually shrunken, and
there was often peritubular smooth
muscle hyperplasia. A focal area of
lymphocyte infiltration with germinal
center formation was found in one testis.

104 Journal of Wildlife Diseases Vol. 11, January, 1975
Interstitial cells were numerous in tes-
tes of two deer, few in one deer, and
absent in three deer. Where present, they
had foamy cytoplasm (Figure 3) which
contained oil red 0-positive droplets. In
order to determine whether the hyperpla-
sia in the two deer was relative or abso-
lute, the numbers of interstitial cells in
70 high power fields (HPF) were deter-
mined in atrophic and normal testes. The
average number in atrophic testes was
50 interstitial cells/HPF, whetreas in
normal testes the average was 13 cells/
HPF. Since the weight, and presumably
the volume, of atrophic testes was only
one-fifth to one-tenth of normal testes,
the hyperplasia was judged to be rela-
tive.
In the testicular parenchyma of three
animals, there were occasional arterioles
with intimal thickening and endothelial
cell proliferation (Figure 4). Rare yes-
sels had a perivascular mononuclear cell
infiltration. Arteriolar walls were mar-
kedly thickened in the testes of one buck.
Such lesions were not found in arterioles
of the pampiniform plexus of any of the
animals.
DISCUSSION
In studies of the antler cycle in white-
tailed deer, Wisbocki showed that rising
testosterone levels during the summer
months correlated with cessation of
antler growth and shedding of velvet and
that these events did not occur in ex-
perimentally castrated deer.1’ Antler ab-
normalities similar to castrated deer and
the back of masculinization during the
rut suggest deficiency or inhibition of
testosterone activity in the deer of this
study. This correlates with absolute or
FIGURE 3. Testis from deer with testicular atrophy taken during the fall “rut”. Seminiferous
tubules are small and hypocellular with only Sertoli cells remaining. Interstitial cells are
vacuolated and relatively hyperplastic. H&E, X250.

-4.
 b - ,- -
-- ,-‘-
-‘V - ____ -

_____
FIGURE 4. Arteriole from atrophic testis showing inflammation and proliferative changes in
the tunica intima (arrow). H&E, X250.
Journal of Wildlife Diseases Vol. 11, January, 1975 105
relative diminution in interstitial cell
numbers. When present, the cells were
markedly vacuolated, perhaps due to in-
hibition of secretory activity.
Although the etiology and pathogene-
sis of these lesions remain obscure, there
are several general possibilities if a
common mechanism can be inferred.
That the testicular atrophy might have
resulted from an unknown toxicity, vas-
cular obstruction, or congenital hypo-
plasia rather than an infectious process
is suggested by the lack of a consistent
inflammatory cell infiltrate. However,
viral or bacterial causes cannot be ex-
cluded, considering the chronicity of the
lesions when observed.
The apparent increase in the incidence
of testicular atrophy following a wildfire,
as described in this report, might suggest
that ingestion of estrogenic or gonado-
toxic plants or chemicals used in fire or
brush suppression could be involved in
the etiology of the lesions. Estrogenic
substances, however, have been shown to
cause velvet shedding, not retention, in
deer.’ This leaves open the possibility of
other plant or chemical (diesel oil, 2.4-D,
2,4-5-T) toxicities.
Alternatively, the testicular lesions
could have a vascular basis. Atrophy of
seminiferous tubular epithelium and
interstitial cells progressing to connective
tissue replacement has been described
in rats following various degrees of ex-
perimental occlusion of the spermatic
artery.7 A high incidence of arterial
eleophoriasis has been reported in Cob-
umbian black-tailed deer in California”
and the vascular lesions caused by E/eo-
phora sc/ineideri in elk have been de-
scribed.’ Whether the testicular infarct
in one case was a primary event or
secondary to torsion following atrophy
is unknown, but the latter seems more
likely.

106 Journal of Wildlife Diseases Vol. 11, January, 1975
Received for publication 17 June 1974
The testicular lesions described herein the latter, and many animals of the pre-
appear to be very similar histologically sent group were observed to have nor-
to those described in Kleinfelter’s syn- mally developed antlers early in life.
drome in man and genital hypoplasia of This possibility can be excluded only by
white-tailed deer.’ However, there were chromosomal studies of affected animals.
no gross penile abnormalities as noted in
Acknowledgement
We are grateful to W. M. Longhurst, Division of Agricultural Sciences, Hopland Field Sta-
tion, University of California, Davis, and to K. Benirschke, Department of Reproductive Medi-
cine, University of California, San Diego, for their assistance and suggestions during this study.
LITERATURE CITED
I. ADCOCK, J. L. and C. P. HIBLER. 1969. Vascular and neuro-ophthalmic
pathology of elaeophorosis in elk. Path. Vet. 6: 185-213.
2. CLARK, F. C. 1961. Malformed antlers of deer. Calif. Fish and Game 2:
119-123.
3. FERGUSON-SMITH, M. A., B. LENNOX, W. S. MACK and J. S. S. STEW-
ART. 1957. Kleinfelter’s syndrome. Frequency and testicular morphology
in relation to nuclear sex. Lancet 2: 167-169.
4. GOSS, R. J. 1968. Inhibition of growth and shedding of antlers by sex hor-
mones. Nature 220: 83-85.
5. MARBURGER, R. G., R. M. ROBINSON and J. W. THOMAS. 1967. Genital
hypoplasia of white-tailed deer. J. Mammal. 48: 674-676.
6. MURPHY, B. D. and R. E. CLUGSTON. 1971. Bilateral testicular degeneration
in a wild mule deer. J. Wildl. Dis. 7: 67-69.
7. OETTLE, A. G. and R. G. HARRISON. 1953. The histological changes pro-
duced in the rat testis by temporary and permanent occlusion of the testicu-
lar artery. J. Path. Bact. 64: 273-296.
8. ROBINSON, R. M., J. W. THOMAS and R. G. MARBURGER. 1967. Abnor-
mal antler shedding associated with hypogonadism in central Texas deer.
Southwest. Vet. 20: 93-98.
9. TAYLOR, D. 0. N., J. W. THOMAS and R. G. MARBURGER. 1964. Ab-
normal antler growth associated with hypogonadism in white-tailed deer in
Texas. Amer. J. Vet. Res. 25: 179-185.
10. THOMAS, J. W., R. M. ROBINSON and R. G. MARBURGER. 1964. Hypo-
gonadism in white-tailed deer of the central mineral region in Texas. Trans.
N. Amer. Wildlife Conf. 29: 225-236.
11. WEINMANN, C. J., J. R. ANDERSON, W. M. LONGHURST and G. CON-
NOLLY. 1973. Filarial worms of Columbian black-tailed deer in California.
J. Wildl. Dis. 9: 213-220.
12. WISLOCKI, G. B., J. C. AUB and C. M. WALDO. 1947. The effects of
gonadectomy and the administration of testosterone proportionate on the
growth of antlers in male and female deer. Endocrinology 40: 202-224.