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A modified technique for semen collection by electroejaculation in the domestic cat
THERIOGENOLOGY
A MODIFIED TECHNIQUE BY ELECTROEJACULATION
FOR SEMEN COLLECTION IN THE DOMESTIC CAT
Mary A. Herron', Claudia L. Barton2, and B. Applegate Department of Veterinary Anatomyl, Department of Small Animal Medicine and Surgery2, and Department of Educational Psychology3, Texas A & M University, College Station, Texas 77843 Received
for publication: Accepted:
November 2, 1985 July 23, 1986
ABSTRACT A method was developed for collecting feline semen by electroejaculation combined with the use of a urethral catheter. The catheter facilitated handling the small volumes of semen for laboratory analysis. In 14 cats, semen volumes ranged from 0.019 to 0.284 ml (mean 0.076) and spermatozoa counts of ejaculates collected in the catheter ranged from 0.32 to 49.60 X lo6 (mean Nine individuals were evaluated for retrograde 11.64 X 106). ejaculation by quantitation of spermatozoa in pre-ejaculation and post-ejaculation urine samples. No spermatozoa were detected in pre-ejaculation samples but post-ejaculation urine samples contained from 0 to 11.88 X lo6 (mean 4.55 X 106) spermatozoa. The antegrade portion of the ejaculate contained from 6.3 to 100% (mean 59.1%) of the total number of spermatozoa ejaculated. Key words:
feline, electroejaculation,
semen
INTRODUCTION Semen is collected from animals for fertility examination, insemination, artificial and long-term storage. Although electroejaculation is a routine method of semen collection in some species, it has not commonly been used in the collection of feline semen. Consequently, there is a paucity of reports concerning normal feline semen characteristics or collection techniques for clinical application in feline practice (l-5). The mechanics of electroejaculation in the cat are complicated by the cat's resistance to restraint and the extremely small volume of fluid ejaculated. This paper describes a modified collection This research was supported Surgery Research Fund.
SEPTEMBER
by the
1986 VOL. 26 NO. 3
Small
Animal
Medicine
and
357
technique, technique, the cat.
reports characteristics and documents occurrence
MATERIALS
of semen collected by this of retrograde ejaculation in
AND METHODS
Fourteen random-source adult male cats, weighing 3.2 to 4.5 kg, were housed in an isolated group during the months of June and July and were exposed to the normal outdoor temperature and The cats did not have the photoperiod of central Texas. opportunity to breed for a minimum of two weeks prior to the A commercial dry cat food was fed once beginning of the study. each day, and water was freely available. were premeditated with cats Before ejaculation, glycopyrrolatea (0.01 mg/kg, subcutaneously), anesthetized with ketamine hydrochlorideb (30 mg/kg, intxamuscularly), and placed in lateral recumbency. An open-end tom cat catheter (12.3 cm, 3.5 frjc was insertedinthe urethra to a depth of 5 cm, so that A small hole the tip rested caudal to the seminal colliculus. (0.5 cm diameter) was made in a 4-cm by 12-cm strip of elastic the penis bandage.d The bandage was applied to the perineum,and To prevent and catheter were exposed through the opening. expulsion of the catheter during the ejaculation procedure, it was held in place by a small strip of elastic bandage which encircled the catheter and attached to the perineal bandage (Figure 1). The electroejaculation unit was composed of a wave-form The probe was a polyester and generator, ammeter, and probe. with five epoxy resin cylinder (12 cm long, 1.5 cm diameter) parallel stainless steel wire electrodes 18.5 cm long1 arranged The longitudinally over 270 degrees of the probe circumference. outer and central electrodes were connected in common, and the remaining two electrodes were also connected in common. The probe was lubricated sparingly with a sterile surgical inserted to a depth of 6 to 7 cm into the rectum, lubricant,e cleaned if contaminated with feces, and reinserted. withdrawn, The central electrode was oriented over the prostate and pelvic aRobinul-V, A. H. Robins Co, Richmond, VA. bVetalar, Parke-Davis, Morris Plains, NJ. 'Torn Cat Catheter, Monoject (a division of Sherwood Medical), St Louis,M1). d Elasticon, Johnson & Johnson Products, Inc, New Brunswick, NJ. eSurgilube, Byk-Gulden, Inc, Melville, NY.
358
SEPTEMBER 1986 VOL. 26 NO. 3
THERIOGENOLOGY
Figure 1. Anesthetized cat with urethral catheter, perineal bandage, and rectal probe in place symphysis and the probe was gently pressed ventrally. Sine wave stimuli at a frequency of 60 Hz were applied in three sets of four minutes' duration each, with 5-min rest periods between the Initial voltage was determined by increasing the voltage sets. from 0 to the voltage at which the rear limbs extended and the digits flexed. This voltage was designated as the minimum voltage and constituted the voltage used throughout the first set; voltage measurements were expressed as peak-to-peak values. The stimulus was delivered by oscillating the voltage control between 0 and the pre-determined minimum voltage. The minimum voltage was delivered for approximately 2 set before return to 0 A 2-see wait was observed before the next stimulus was V. In the second set, stimuli were delivered in the same initiated. manner, but the voltage was increased by 1 V; in the third set, the voltage was increased over the minimum voltage by 2 V. Milliamperes were observed for each stimulus, and an average for each set was recorded. The antegrade ejaculate was defined as the total seminal product collected from the catheter at the end of the three sets of stimuli. spermatozoa count, motility, and morphology were Volume,
SEPTEMBER
1986 VOL. 26 NO. 3
359
THERIOGENOLOGY
recorded for each antegrade ejaculate. Volume was determined by measuring the ejaculate in the catheter to the nearest 0.1 cm. The catheter had been previously calibrated by filling it with measured volumes (to nearest 0.001 ml) of fluid and making centimeter measurements (to nearest 0.1 cm) of the fluid in the tube. A table was constructed to convert centimeter measurements to milliliters. Each sample was diluted with 0.2 ml of warmed saline (36O C). One drop of the diluted sample was examined under a microscope to estimate the percentage of forward-moving spermatozoa, one drop was smeared on a glass slide and stained with a quick Wright's stainf for morphologic examination, and a portion was diluted (1:50) in a microcollection systemg for hemacytometer determination of spermatozoa counts. In five cats, post-ejaculation urine was collected by cystocentesis and examined microscopically for presence of spermatozoa. In nine before and after ejaculation using a cats, urine was collected closed-end catheterC and a saline bladder wash. Spermatozoa counts were determined in both samples, and the count for the post-ejaculation urine was designated as the retrograde The sum of the retrograde and antegrade spermatozoa ejaculate. counts constituted the spermatozoa count of the total ejaculate. The mean and standard error of the mean were calculated for the antegrade volume and for the spermatozoa counts of the antegrade, retrograde, and total ejaculates. RESULTS The minimum voltage required to stimulate extension of the rear limbs and flexion of the digits varied among cats from 5 to 10 v. Semen was observed in the exposed portion of the catheter during the first set of stimuli in 4/14 cats, during the second The voltage set in 8/14, and during the third set in 2/14. during the set in which semen was detected in the catheter ranged from 5tolOV,whilethemilliampererecording ranged from 15to The cats' physical response to stimulation tended to 31. in intensity during the latter half of the 4-min decrease stimulation. The transparency of the catheter allowed easy visualization of the semen as it was ejaculated, and the volume of the ejaculate could be measured and easily transferred to a The ejaculate was generally clear to dilution vial for analysis. cloudy in appearance: however, one cat produced a slightly bloodtinged seminal fluid and developed mild dysuria of two days' rDiff-Quik, Harleco, Gibbstown, NY. gunopette, Becton-Dickinson and Co, Rutherford,
360
NJ.
SEPTEMBER 1986 VOL. 26 NO. 3
THERIOGENOLOGY
duration following the procedure. Antegrade ejaculate volume ranged from 0.019 to 0.284 ml with a mean of 0.076 +/- 0.018 ml (SEMI (Table 1). The antegrade with a mean ejaculate contained 0.32 to 49.60 x lo6 spermatozoa of 11.64 +/- 4.58 x lo6 (SEM). Spermatozoa motility estimates for the 14 samples were 50 to 90%, and morphologic abnormalities were observed in 5 to 14% of the spermatozoa. All five postejaculation urine samples collected by cystocentesis contained Pre-ejaculation urine samples of the nine cats spermatozoa. evaluated for retrograde ejaculation had 0 spermatozoa whil; post-ejaculation urine samples contained 0 to 11.88 x 10 spermatozoa (mean 4.55 +/- 1.18 x lo6 (SEM)). Total spermatozoa counts ranged from 3.89 to 53.12 x 106, with a mean spermatozoa The number of spermatozoa count of 16.74 +/- 5.10 x lo6 (SEM). Table
1.
Volume and spermatozoa counts for feline semen samples collected by electroejaculation Spermatozoa
Cat number
Antegrade volume(ml)
Antegrade
Counts
Retrograde
(x 106)
Total
% Spermatozoa in antegrade sample
1 2 3 4 5 6 7 8 9 10 11 12 13 14
0.067 0.049 0.019 0.029 0.030 0.284 0.038 0.055 0.046 0.112 0.052 0.106 0.078 0,095
49.40 1.80 0.48 0.74 0.69 49.60 0.32 4.18 9.84 15.80 7.32 1.36 19.61 1.76
+ + + + + 3.52 4.73 3.15 7.00 6.50 0.00 11.88 2.00 2.13
53.12 5.05 7.33 16.84 22.30 7.32 13.24 21.61 3.89
93.4 6.3 57.0 58.4 70.9 100.0 10.3 90.7 45.2
Mean SEM*
0.076 0.018
11.64 4.58
4.55 1.18
16.74 5.10
59.1 11.4
*Standard error of the mean. + = Spermatozoa present but not quantitated.
SEPTEMBER 1986 VOL. 26 NO. 3
361
in the antegrade ejaculate represented as little as 6.3% to as much as 100% (mean 59.1%) of the total number of spermatozoa.
DISCUSSION The described technique induced ejaculation in all cats tested. The use of the urethral catheter as a collection device is unique to this electroejaculation procedure and has several advantages: 1) use of a urethral catheter allows the collection to be performed by one operator, if necessary; 2) the semen sample may be observed for color and volume through the catheter wall during the ejaculation procedure; and 3) a catheter facilitates handling of the small volume of the feline ejaculate. The sample contained within the catheter may either be directly inseminated into a queen or transported to a laboratory for analysis. Semen samples were always noted in the catheter during the first half of the successful stimulus set. Extension of the rear limbs lessened in intensity during the latter half of each set, supporting a previous suggestion that the spinal nerves become refractory to stimulation over time (4). As would be expected, clear samples had few spermatozoa, while cloudy samples contained Motility was influenced by the a greater number of spermatozoa. No attempt length of time the sample remained in the catheter. was made to warmtheexposedportion of the catheter,andin some cases the sampleremainedinthecatheter for 20 to25 min before Such samples usually had motility estimates of 50 examination. abnormalities in 5 to 70%. Thirteen of the cats had morphologic one cat had abnormalities in 14%. to 9% of the spermatozoa; Abnormalities most commonly noted were bent or broken tails and Abnormalities such as abnormal head shapes and detached heads. midpieces were present only rarely. Semen volume,s and spermatozoa numbers obtained using the catheter technique described in this paper have similarities to values reported for ejaculates collected without a catheter (lsince 31. It is difficult, however, to make direct correlations the collection technique for each study also varied in frequency, and duration of stimulation. pattern, The volume of the antegrade ejaculate ranged from 0.019 to 0.284 ml and was similar to the minimum (0.018 ml) and maximum (0.202 ml) volumes reported by Johnstone (1) but less than volumes reported elsewhere f2, 3). Volume is not a reliable criterion to assess semen quality obtained by electroejaculation since electrical stimulation (4) and duration of stimulation (1) have each been shown to increase
362
SEPTEMBER 1986 VOL. 26 ,NO. 3
THERIOGENOLOGY
It has been suggested that the semen volume in the cat. increased volume is produced by the accessory sex glands (1). The mean value of 11.64 x lo6 spermatozoa per antegrade ejaculate is similar to the overall mean total number of spermatozoa for four ejaculates of 13.92 x lo6 reported for nine cats (2). It is also similar to individual means of 6 to 13 x lo6 spermatozoa based on a variable number of collections in each of four cats (11, but less than the mean value of 28 x 106 reported in an earlier study (4). It is possible that the cats in the latter study represented individuals selected for ejaculatory performance. The apparent large number of spermatozoa present in postejaculation urine collected by cystocentesis prompted the suspicion that a portion of the ejaculate was being deposited in the bladder. For this reason, urine samples were collected from 9 cats before and after ejaculation for quantitative analysis. Remarkably, the post-ejaculation urine sometimes contained the major portion of the spermatozoa ejaculated. Table 1 shows that the number of spermatozoa in the antegrade ejaculate accounted for 6.3 to 100% (mean 59.1%) of the total ejaculate count. One other study of eight cats has reported that the antegrade ejaculate contained from 5.7 to 60.7% of the total number of spermatozoa released during electroejaculation (6). Retrograde ejaculation is recognized in man as a rare cause of infertility and is apparently due to incomplete closure of the internal sphincter of the bladder (7). In the cat, retrograde flow of semen during electroejaculation may result from electrical stimulation. It is also possible that retrograde flow of a percentage of the spermatozoa ejaculated occurs during natural copulation in the cat; this awaits further study. Retrograde ejaculation limits but does not negate the usefulness of semen samples produced by electroejaculation in the assessment of fertility of the male cat. Electroejaculated samples may be used both for morphology and motility studies and for artificial insemination. The clinician should be aware that retrograde ejaculation does occur during electrical stimulation and that a better assessment of total number of spermatozoa per ejaculate would be obtained by adding the spermatozoa number in the antegrade ejaculate to the number in the urine collected after ejaculation. REFERENCES 1. Johnstone, I. Electroejaculation in the domestic cat. Vet. J. $l_:155-158 (1984).
SEPTEMBER 1986 VOL. 26 NO. 3
Aust.
363
THERIOGENOLOGY
2. Pineda, MB., Dooley, M.P. and Martin, P.A. Long-term study on the effects of electraejaculation on seminal characteristics of the domestic cat. Am. J. Vet. Res. 45:1038-1041 (1984). 3. Plats, C.C. and Seager, S.W.J. Semen collection by electroejaculation in the domestic cat. J. Am. Vet. Med. Assoc. 173:1353-1355 (1978). 4. Platz, C.C., Wildt, D.E. and Seager, S.W,J. Pregnancy in the domestic cat after artificial insemination with previously frozen spermatozoa. J. Reprod. Fert. 52:279-282 (1978). 5. Seager, S.W.J. Electroejaculation of czs (domestic and captive wild felidae). In: Klemm, W.R. (ed), Applied Electronics for Veterinary Medicine and Animal Physiology. Charles C. Thomas, Springfield, IL , 1976, pp. 410-418. 6. Dooley, M.P., Pineda, M.H., Hopper, J.G. and HSU, W.H. Retrograde flow of semen caused by electroejaculation in the domestic cat. Proc. 10th Int. Cong. Anim. Reprod. & A-I., Vol III, Brief Commun. No. 363, (1984). 7. Lipschultz, L.I., McConnell, J., and Benson, G.S. Current concepts of the mechanisms of ejaculation: Normal and abnormal states. J. Reprod. Med. 26_:499-507 (1981).
364
SEPTEMBER 1986 VOL. 26 NO. 3
A MODIFIED TECHNIQUE BY ELECTROEJACULATION
FOR SEMEN COLLECTION IN THE DOMESTIC CAT
Mary A. Herron', Claudia L. Barton2, and B. Applegate Department of Veterinary Anatomyl, Department of Small Animal Medicine and Surgery2, and Department of Educational Psychology3, Texas A & M University, College Station, Texas 77843 Received
for publication: Accepted:
November 2, 1985 July 23, 1986
ABSTRACT A method was developed for collecting feline semen by electroejaculation combined with the use of a urethral catheter. The catheter facilitated handling the small volumes of semen for laboratory analysis. In 14 cats, semen volumes ranged from 0.019 to 0.284 ml (mean 0.076) and spermatozoa counts of ejaculates collected in the catheter ranged from 0.32 to 49.60 X lo6 (mean Nine individuals were evaluated for retrograde 11.64 X 106). ejaculation by quantitation of spermatozoa in pre-ejaculation and post-ejaculation urine samples. No spermatozoa were detected in pre-ejaculation samples but post-ejaculation urine samples contained from 0 to 11.88 X lo6 (mean 4.55 X 106) spermatozoa. The antegrade portion of the ejaculate contained from 6.3 to 100% (mean 59.1%) of the total number of spermatozoa ejaculated. Key words:
feline, electroejaculation,
semen
INTRODUCTION Semen is collected from animals for fertility examination, insemination, artificial and long-term storage. Although electroejaculation is a routine method of semen collection in some species, it has not commonly been used in the collection of feline semen. Consequently, there is a paucity of reports concerning normal feline semen characteristics or collection techniques for clinical application in feline practice (l-5). The mechanics of electroejaculation in the cat are complicated by the cat's resistance to restraint and the extremely small volume of fluid ejaculated. This paper describes a modified collection This research was supported Surgery Research Fund.
SEPTEMBER
by the
1986 VOL. 26 NO. 3
Small
Animal
Medicine
and
357
technique, technique, the cat.
reports characteristics and documents occurrence
MATERIALS
of semen collected by this of retrograde ejaculation in
AND METHODS
Fourteen random-source adult male cats, weighing 3.2 to 4.5 kg, were housed in an isolated group during the months of June and July and were exposed to the normal outdoor temperature and The cats did not have the photoperiod of central Texas. opportunity to breed for a minimum of two weeks prior to the A commercial dry cat food was fed once beginning of the study. each day, and water was freely available. were premeditated with cats Before ejaculation, glycopyrrolatea (0.01 mg/kg, subcutaneously), anesthetized with ketamine hydrochlorideb (30 mg/kg, intxamuscularly), and placed in lateral recumbency. An open-end tom cat catheter (12.3 cm, 3.5 frjc was insertedinthe urethra to a depth of 5 cm, so that A small hole the tip rested caudal to the seminal colliculus. (0.5 cm diameter) was made in a 4-cm by 12-cm strip of elastic the penis bandage.d The bandage was applied to the perineum,and To prevent and catheter were exposed through the opening. expulsion of the catheter during the ejaculation procedure, it was held in place by a small strip of elastic bandage which encircled the catheter and attached to the perineal bandage (Figure 1). The electroejaculation unit was composed of a wave-form The probe was a polyester and generator, ammeter, and probe. with five epoxy resin cylinder (12 cm long, 1.5 cm diameter) parallel stainless steel wire electrodes 18.5 cm long1 arranged The longitudinally over 270 degrees of the probe circumference. outer and central electrodes were connected in common, and the remaining two electrodes were also connected in common. The probe was lubricated sparingly with a sterile surgical inserted to a depth of 6 to 7 cm into the rectum, lubricant,e cleaned if contaminated with feces, and reinserted. withdrawn, The central electrode was oriented over the prostate and pelvic aRobinul-V, A. H. Robins Co, Richmond, VA. bVetalar, Parke-Davis, Morris Plains, NJ. 'Torn Cat Catheter, Monoject (a division of Sherwood Medical), St Louis,M1). d Elasticon, Johnson & Johnson Products, Inc, New Brunswick, NJ. eSurgilube, Byk-Gulden, Inc, Melville, NY.
358
SEPTEMBER 1986 VOL. 26 NO. 3
THERIOGENOLOGY
Figure 1. Anesthetized cat with urethral catheter, perineal bandage, and rectal probe in place symphysis and the probe was gently pressed ventrally. Sine wave stimuli at a frequency of 60 Hz were applied in three sets of four minutes' duration each, with 5-min rest periods between the Initial voltage was determined by increasing the voltage sets. from 0 to the voltage at which the rear limbs extended and the digits flexed. This voltage was designated as the minimum voltage and constituted the voltage used throughout the first set; voltage measurements were expressed as peak-to-peak values. The stimulus was delivered by oscillating the voltage control between 0 and the pre-determined minimum voltage. The minimum voltage was delivered for approximately 2 set before return to 0 A 2-see wait was observed before the next stimulus was V. In the second set, stimuli were delivered in the same initiated. manner, but the voltage was increased by 1 V; in the third set, the voltage was increased over the minimum voltage by 2 V. Milliamperes were observed for each stimulus, and an average for each set was recorded. The antegrade ejaculate was defined as the total seminal product collected from the catheter at the end of the three sets of stimuli. spermatozoa count, motility, and morphology were Volume,
SEPTEMBER
1986 VOL. 26 NO. 3
359
THERIOGENOLOGY
recorded for each antegrade ejaculate. Volume was determined by measuring the ejaculate in the catheter to the nearest 0.1 cm. The catheter had been previously calibrated by filling it with measured volumes (to nearest 0.001 ml) of fluid and making centimeter measurements (to nearest 0.1 cm) of the fluid in the tube. A table was constructed to convert centimeter measurements to milliliters. Each sample was diluted with 0.2 ml of warmed saline (36O C). One drop of the diluted sample was examined under a microscope to estimate the percentage of forward-moving spermatozoa, one drop was smeared on a glass slide and stained with a quick Wright's stainf for morphologic examination, and a portion was diluted (1:50) in a microcollection systemg for hemacytometer determination of spermatozoa counts. In five cats, post-ejaculation urine was collected by cystocentesis and examined microscopically for presence of spermatozoa. In nine before and after ejaculation using a cats, urine was collected closed-end catheterC and a saline bladder wash. Spermatozoa counts were determined in both samples, and the count for the post-ejaculation urine was designated as the retrograde The sum of the retrograde and antegrade spermatozoa ejaculate. counts constituted the spermatozoa count of the total ejaculate. The mean and standard error of the mean were calculated for the antegrade volume and for the spermatozoa counts of the antegrade, retrograde, and total ejaculates. RESULTS The minimum voltage required to stimulate extension of the rear limbs and flexion of the digits varied among cats from 5 to 10 v. Semen was observed in the exposed portion of the catheter during the first set of stimuli in 4/14 cats, during the second The voltage set in 8/14, and during the third set in 2/14. during the set in which semen was detected in the catheter ranged from 5tolOV,whilethemilliampererecording ranged from 15to The cats' physical response to stimulation tended to 31. in intensity during the latter half of the 4-min decrease stimulation. The transparency of the catheter allowed easy visualization of the semen as it was ejaculated, and the volume of the ejaculate could be measured and easily transferred to a The ejaculate was generally clear to dilution vial for analysis. cloudy in appearance: however, one cat produced a slightly bloodtinged seminal fluid and developed mild dysuria of two days' rDiff-Quik, Harleco, Gibbstown, NY. gunopette, Becton-Dickinson and Co, Rutherford,
360
NJ.
SEPTEMBER 1986 VOL. 26 NO. 3
THERIOGENOLOGY
duration following the procedure. Antegrade ejaculate volume ranged from 0.019 to 0.284 ml with a mean of 0.076 +/- 0.018 ml (SEMI (Table 1). The antegrade with a mean ejaculate contained 0.32 to 49.60 x lo6 spermatozoa of 11.64 +/- 4.58 x lo6 (SEM). Spermatozoa motility estimates for the 14 samples were 50 to 90%, and morphologic abnormalities were observed in 5 to 14% of the spermatozoa. All five postejaculation urine samples collected by cystocentesis contained Pre-ejaculation urine samples of the nine cats spermatozoa. evaluated for retrograde ejaculation had 0 spermatozoa whil; post-ejaculation urine samples contained 0 to 11.88 x 10 spermatozoa (mean 4.55 +/- 1.18 x lo6 (SEM)). Total spermatozoa counts ranged from 3.89 to 53.12 x 106, with a mean spermatozoa The number of spermatozoa count of 16.74 +/- 5.10 x lo6 (SEM). Table
1.
Volume and spermatozoa counts for feline semen samples collected by electroejaculation Spermatozoa
Cat number
Antegrade volume(ml)
Antegrade
Counts
Retrograde
(x 106)
Total
% Spermatozoa in antegrade sample
1 2 3 4 5 6 7 8 9 10 11 12 13 14
0.067 0.049 0.019 0.029 0.030 0.284 0.038 0.055 0.046 0.112 0.052 0.106 0.078 0,095
49.40 1.80 0.48 0.74 0.69 49.60 0.32 4.18 9.84 15.80 7.32 1.36 19.61 1.76
+ + + + + 3.52 4.73 3.15 7.00 6.50 0.00 11.88 2.00 2.13
53.12 5.05 7.33 16.84 22.30 7.32 13.24 21.61 3.89
93.4 6.3 57.0 58.4 70.9 100.0 10.3 90.7 45.2
Mean SEM*
0.076 0.018
11.64 4.58
4.55 1.18
16.74 5.10
59.1 11.4
*Standard error of the mean. + = Spermatozoa present but not quantitated.
SEPTEMBER 1986 VOL. 26 NO. 3
361
in the antegrade ejaculate represented as little as 6.3% to as much as 100% (mean 59.1%) of the total number of spermatozoa.
DISCUSSION The described technique induced ejaculation in all cats tested. The use of the urethral catheter as a collection device is unique to this electroejaculation procedure and has several advantages: 1) use of a urethral catheter allows the collection to be performed by one operator, if necessary; 2) the semen sample may be observed for color and volume through the catheter wall during the ejaculation procedure; and 3) a catheter facilitates handling of the small volume of the feline ejaculate. The sample contained within the catheter may either be directly inseminated into a queen or transported to a laboratory for analysis. Semen samples were always noted in the catheter during the first half of the successful stimulus set. Extension of the rear limbs lessened in intensity during the latter half of each set, supporting a previous suggestion that the spinal nerves become refractory to stimulation over time (4). As would be expected, clear samples had few spermatozoa, while cloudy samples contained Motility was influenced by the a greater number of spermatozoa. No attempt length of time the sample remained in the catheter. was made to warmtheexposedportion of the catheter,andin some cases the sampleremainedinthecatheter for 20 to25 min before Such samples usually had motility estimates of 50 examination. abnormalities in 5 to 70%. Thirteen of the cats had morphologic one cat had abnormalities in 14%. to 9% of the spermatozoa; Abnormalities most commonly noted were bent or broken tails and Abnormalities such as abnormal head shapes and detached heads. midpieces were present only rarely. Semen volume,s and spermatozoa numbers obtained using the catheter technique described in this paper have similarities to values reported for ejaculates collected without a catheter (lsince 31. It is difficult, however, to make direct correlations the collection technique for each study also varied in frequency, and duration of stimulation. pattern, The volume of the antegrade ejaculate ranged from 0.019 to 0.284 ml and was similar to the minimum (0.018 ml) and maximum (0.202 ml) volumes reported by Johnstone (1) but less than volumes reported elsewhere f2, 3). Volume is not a reliable criterion to assess semen quality obtained by electroejaculation since electrical stimulation (4) and duration of stimulation (1) have each been shown to increase
362
SEPTEMBER 1986 VOL. 26 ,NO. 3
THERIOGENOLOGY
It has been suggested that the semen volume in the cat. increased volume is produced by the accessory sex glands (1). The mean value of 11.64 x lo6 spermatozoa per antegrade ejaculate is similar to the overall mean total number of spermatozoa for four ejaculates of 13.92 x lo6 reported for nine cats (2). It is also similar to individual means of 6 to 13 x lo6 spermatozoa based on a variable number of collections in each of four cats (11, but less than the mean value of 28 x 106 reported in an earlier study (4). It is possible that the cats in the latter study represented individuals selected for ejaculatory performance. The apparent large number of spermatozoa present in postejaculation urine collected by cystocentesis prompted the suspicion that a portion of the ejaculate was being deposited in the bladder. For this reason, urine samples were collected from 9 cats before and after ejaculation for quantitative analysis. Remarkably, the post-ejaculation urine sometimes contained the major portion of the spermatozoa ejaculated. Table 1 shows that the number of spermatozoa in the antegrade ejaculate accounted for 6.3 to 100% (mean 59.1%) of the total ejaculate count. One other study of eight cats has reported that the antegrade ejaculate contained from 5.7 to 60.7% of the total number of spermatozoa released during electroejaculation (6). Retrograde ejaculation is recognized in man as a rare cause of infertility and is apparently due to incomplete closure of the internal sphincter of the bladder (7). In the cat, retrograde flow of semen during electroejaculation may result from electrical stimulation. It is also possible that retrograde flow of a percentage of the spermatozoa ejaculated occurs during natural copulation in the cat; this awaits further study. Retrograde ejaculation limits but does not negate the usefulness of semen samples produced by electroejaculation in the assessment of fertility of the male cat. Electroejaculated samples may be used both for morphology and motility studies and for artificial insemination. The clinician should be aware that retrograde ejaculation does occur during electrical stimulation and that a better assessment of total number of spermatozoa per ejaculate would be obtained by adding the spermatozoa number in the antegrade ejaculate to the number in the urine collected after ejaculation. REFERENCES 1. Johnstone, I. Electroejaculation in the domestic cat. Vet. J. $l_:155-158 (1984).
SEPTEMBER 1986 VOL. 26 NO. 3
Aust.
363
THERIOGENOLOGY
2. Pineda, MB., Dooley, M.P. and Martin, P.A. Long-term study on the effects of electraejaculation on seminal characteristics of the domestic cat. Am. J. Vet. Res. 45:1038-1041 (1984). 3. Plats, C.C. and Seager, S.W.J. Semen collection by electroejaculation in the domestic cat. J. Am. Vet. Med. Assoc. 173:1353-1355 (1978). 4. Platz, C.C., Wildt, D.E. and Seager, S.W,J. Pregnancy in the domestic cat after artificial insemination with previously frozen spermatozoa. J. Reprod. Fert. 52:279-282 (1978). 5. Seager, S.W.J. Electroejaculation of czs (domestic and captive wild felidae). In: Klemm, W.R. (ed), Applied Electronics for Veterinary Medicine and Animal Physiology. Charles C. Thomas, Springfield, IL , 1976, pp. 410-418. 6. Dooley, M.P., Pineda, M.H., Hopper, J.G. and HSU, W.H. Retrograde flow of semen caused by electroejaculation in the domestic cat. Proc. 10th Int. Cong. Anim. Reprod. & A-I., Vol III, Brief Commun. No. 363, (1984). 7. Lipschultz, L.I., McConnell, J., and Benson, G.S. Current concepts of the mechanisms of ejaculation: Normal and abnormal states. J. Reprod. Med. 26_:499-507 (1981).
364
SEPTEMBER 1986 VOL. 26 NO. 3