# Canine Semen Collection and Evaluation: A Practical Protocol ## Key Takeaways - Canine ejaculates consist of three distinct fractions: a clear prostatic fluid (fraction 1), a sperm-rich milky fraction (fraction 2), and a larger volume of prostatic fluid (fraction 3); accurate collection requires separating these fractions, with fraction 2 being critical for fertility assessment. - Semen evaluation serves to identify subfertile males and estimate conception likelihood, with progressive motility (>70% in fresh semen) and morphology (>80% normal) being key indicators, though interpretation must consider individual history and age. - Manual semen collection is the preferred method, requiring a warmed collection vessel (approx. 37°C) to prevent cold shock and immediate evaluation (within 15-30 minutes) of the sperm-rich fraction to minimize motility decline. - Macroscopic assessment includes volume, color, and consistency, with a milky white sperm-rich fraction indicating adequate sperm density, while blood or yellow discoloration suggests contamination or pathology requiring further investigation. - Microscopic evaluation involves assessing progressive motility (ideally >70%), sperm concentration (20-300 x 10⁶/mL in fraction 2), total sperm count (100-2000 x 10⁶ per ejaculate), and morphology (>80% normal), with seminal alkaline phosphatase useful for distinguishing true azoospermia from incomplete collection. - Interpretation of results necessitates a holistic approach, considering the reason for collection, sexual rest period (2-5 days recommended), and age-related changes (e.g., progressive motility decline in males ≥7 years), with repeat evaluations recommended for ambiguous findings. --- This article provides a step-by-step clinical protocol for manual semen collection and macroscopic and microscopic evaluation in the dog. It is written for practicing veterinarians who perform breeding soundness examinations, investigate male infertility, or provide artificial insemination services. The procedures described apply to the collection of fresh semen for immediate evaluation and insemination, advanced cryopreservation techniques are outside the scope of this article. Semen evaluation in the dog serves two distinct purposes: identifying subfertile or infertile males and estimating the likelihood of conception for a given mating or insemination. The predictive value of individual semen parameters remains an area of active investigation. A longitudinal study of 39 Labrador retriever males in a guide dog breeding program established reference values for sperm endpoints in fertile males and demonstrated that progressive motility declined only in males aged 7 years or older, while other parameters remained stable across age groups. This finding underscores the importance of interpreting semen quality in the context of the individual male and his breeding history instead of relying on a single threshold value. A retrospective analysis of 251 semen examinations from 140 dogs at a university teaching hospital found that the reason for collection, whether evaluation, artificial insemination, cryopreservation, or research, significantly affected semen volume, sperm concentration, and total sperm number. The same study reported that the proportion of morphologically normal spermatozoa was lower in dogs presented specifically for fertility evaluation, suggesting that clinical suspicion of subfertility biases the population being tested. These observations guide the clinician to interpret results with attention to the reason for presentation and to repeat evaluations when findings are ambiguous. ## At a Glance | Parameter | Typical Finding | Clinical Significance | |---|---|---| | Ejaculate volume | 1 to 30 mL total across three fractions | Low volume may indicate incomplete collection or prostatic disease | | Sperm concentration | 20 to 300 x 10⁶ spermatozoa/mL in the sperm-rich fraction | Concentration below 20 x 10⁶/mL warrants investigation | | Total sperm count | 100 to 2000 x 10⁶ spermatozoa per ejaculate | More reliable than concentration alone for fertility assessment | | Progressive motility | Greater than 70% in fresh semen | Values below 50% are associated with reduced fertility | | Morphology | Greater than 80% morphologically normal spermatozoa | Head defects carry greater fertility impact than distal cytoplasmic droplets | | Sperm-rich fraction color | Milky white to opaque | Clear or watery appearance suggests low sperm density | | Seminal alkaline phosphatase | High in epididymal origin, low in prostatic origin | Confirms complete ejaculation when azoospermia is detected | ## Anatomy and Physiology of the Canine Ejaculate The canine ejaculate is produced in three distinct fractions. The first fraction is a small volume of clear, prostatic fluid that appears during the initial phase of erection and serves to flush the urethra. The second fraction is the sperm-rich portion, which is milky white and contains the vast majority of spermatozoa. The third fraction is a larger volume of prostatic fluid that follows the sperm-rich fraction and continues for several minutes during the copulatory tie. The dog does not have seminal vesicles or bulbourethral glands. The prostate is the sole accessory sex gland, and its contribution dominates the total ejaculate volume. This anatomic arrangement means that the sperm-rich fraction is relatively concentrated and that the third fraction contributes little to sperm number but substantially to volume. The epididymis contributes spermatozoa and small amounts of fluid, and the presence of seminal alkaline phosphatase in the ejaculate reflects epididymal contribution. Measurement of this enzyme is useful when azoospermia is detected, because low seminal alkaline phosphatase suggests incomplete ejaculation or obstruction of the epididymis or ductus deferens, whereas high levels confirm that sperm transport through the epididymis has occurred. ## Indications for Semen Collection Semen collection is indicated for breeding soundness examination, prebreeding assessment, investigation of suspected infertility, and artificial insemination with fresh or chilled semen. The Society for Theriogenology provides professional resources on breeding soundness evaluation and reproductive health management that can guide the clinician in structuring these examinations. Collection should be performed before any planned insemination to confirm that the male produces an adequate number of motile, morphologically normal spermatozoa. The timing of collection relative to the female's estrous cycle is not critical for diagnostic purposes, but sexual rest of 2 to 5 days before collection is generally recommended to allow epididymal sperm reserves to accumulate. A male that has been bred repeatedly over several days may produce ejaculates with lower total sperm counts, and this should be considered when interpreting results. Conversely, prolonged sexual rest beyond 7 to 10 days may result in reduced motility due to accumulation of senescent spermatozoa in the epididymis. ## Manual Collection Technique Manual collection, also known as digital manipulation, is the preferred method for the dog because it does not require specialized equipment and yields a high-quality sample. The procedure is performed in a quiet room with a nonslip surface. A teaser female in estrus is helpful but not essential, because many experienced stud dogs will respond to the presence of a receptive female or to olfactory cues from vaginal swabs or soiled bedding. The male is allowed to mount the teaser female or a padded mounting object. The operator stands beside the male and grasps the penis through the prepuce, locating the bulbus glandis. Gentle pressure is applied caudal to the bulbus glandis while the prepuce is retracted. Once the penis is exposed, the operator maintains a firm grip around the penis just caudal to the bulbus, mimicking the constriction of the vaginal vestibule during natural mating. The first fraction, consisting of clear prostatic fluid, is collected into a warmed collection vessel. The second, sperm-rich fraction is identified by its milky appearance and is collected separately. The third fraction follows as the male begins the pelvic thrusting phase and may continue for 5 to 20 minutes, this prostatic fluid can be collected into a separate vessel or discarded depending on the intended use. A collection cone attached to a graduated centrifuge tube is the standard apparatus. The tube should be warmed to approximately 37°C before collection to prevent cold shock to spermatozoa. Latex or silicone collection cones are preferred over plastic bags because they are less traumatic to the penis and allow visual monitoring of the fractions. The sperm-rich fraction should be protected from temperature fluctuations, direct sunlight, and contact with water or disinfectant residues on the collection equipment. ## Handling and Transport of the Ejaculate Spermatozoa are sensitive to temperature, light, and osmotic stress. The collected sample should be maintained at body temperature during the evaluation period. If the sample must be transported to a laboratory, it should be placed in a container that maintains temperature between 20°C and 37°C and protected from vibration. Chilled semen transport requires specific extenders and is beyond the scope of this article. Contamination of the sample with urine, water, or disinfectants can rapidly impair sperm motility. The clinician should inspect the collection cone and tube for cleanliness before use and should discard any sample that appears contaminated. The sperm-rich fraction should be evaluated within 15 to 30 minutes of collection, because motility declines progressively with time even under optimal handling conditions. ## Macroscopic Evaluation The ejaculate is assessed immediately after collection, before any microscopic work. Record total volume, color, and consistency. The canine ejaculate is produced in three fractions. The first fraction is a small, clear prostatic fluid that flushes the urethra. The second, sperm-rich fraction is opaque and white to creamy. The third fraction is a larger volume of clear prostatic fluid. A sample that is uniformly cloudy throughout may represent poor fraction separation during collection. Blood contamination produces a pink to red discolouration and warrants investigation of the prostate or distal reproductive tract. A yellow tint may indicate urine contamination, which is toxic to spermatozoa and reduces motility rapidly. Total volume alone is a poor predictor of fertility because the third fraction contributes the bulk of fluid. What matters more is the volume of the second fraction and the total sperm count derived from concentration multiplied by volume. A dog that produces a large third fraction but a small sperm-rich fraction can appear normal on volume alone while being subfertile. Record each fraction separately when collection is performed with manual manipulation. ## Microscopic Evaluation ### Motility Assessment Place a small drop of the sperm-rich fraction on a warmed glass slide and apply a coverslip. Examine at 200x to 400x magnification using phase-contrast optics if available. The stage warmer should hold the sample at 37°C, since cooling slows spermatozoa and produces falsely low motility readings. Assess both the percentage of progressively motile spermatozoa and the quality of forward motion. A subjective scale of 0 to 100% progressive motility is standard in practice. The [semen evaluation and fertility assessment study in a purebred dog breeding facility](https://pubmed.ncbi.nlm.nih.gov/27658745/) used progressive motility as a primary endpoint and demonstrated that it declines with age, particularly in males aged 7 years and older. Motility is the most labile parameter and deteriorates fastest after collection. Evaluate it within 5 minutes of collection. If the sample is chilled or transported, reassess motility at the time of insemination instead of relying on the initial reading. A sample with good initial motility but poor post-chill motility has a different clinical implication than one with poor motility from the outset. ### Sperm Concentration and Total Count Concentration is measured using a hemocytometer, a spectrophotometer, or a commercial counting chamber designed for canine semen. The hemocytometer remains the reference method. Dilute the sample 1:100 in a sperm diluent or saline, load the chamber, and count the spermatozoa in the central grid. Calculate concentration per milliliter and multiply by the volume of the sperm-rich fraction to obtain the total sperm count. The [retrospective study on variables affecting semen quality in the dog](https://pubmed.ncbi.nlm.nih.gov/29883842/) reported that the reason for collection influenced semen volume, total sperm number, and concentration. Samples collected for evaluation had a lower proportion of normal spermatozoa than those collected for artificial insemination. This finding suggests that dogs presented specifically for fertility investigation are more likely to have underlying abnormalities, and the clinician should interpret results accordingly. ### Morphology Prepare a stained smear using eosin-nigrosin or a Diff-Quik type stain. Examine at 1000x under oil immersion. Count at least 100 spermatozoa and classify each as normal or abnormal. Record the specific abnormalities observed, including head defects, proximal and distal cytoplasmic droplets, midpiece defects, and tail abnormalities. The percentage of morphologically normal spermatozoa is a key predictor of fertility. The breeding facility study cited above established reference values for morphology in a population of fertile Labrador retrievers and found that the proportion of normal spermatozoa was lower in older males. ### Additional Assessments Sperm viability can be assessed with eosin-nigrosin staining, which stains dead spermatozoa pink while live cells exclude the dye. The [review of semen collection and analysis techniques in cats](https://pubmed.ncbi.nlm.nih.gov/16527340/) notes that similar staining methods are used across species, although the small ejaculate volume in cats limits the number of assays that can be performed. In dogs, the larger ejaculate permits a more complete panel. Sperm chromatin structure assay and measurement of reactive oxygen species are research tools, not routine clinical tests, but they may be offered by commercial laboratories when standard parameters are equivocal. ## Interpretation and Reference Values | Parameter | Normal Reference | Abnormal Finding | Clinical Implication | |---|---|---|---| | Total volume | 1 to 30 mL | < 1 mL or > 30 mL | Fractionation error, prostatic disease, incomplete collection | | Sperm-rich fraction volume | 0.5 to 4 mL | Markedly reduced | Incomplete collection, testicular degeneration | | Concentration | 20 to 300 x 10⁶/mL | < 20 x 10⁶/mL | Testicular dysfunction, over-dilution with prostatic fluid | | Total sperm count | 100 to 1000 x 10⁶ | < 100 x 10⁶ | Subfertility, collection error | | Progressive motility | > 70% | < 60% | Sperm damage, cooling, urine contamination, age | | Morphologically normal | > 80% | < 60% | Testicular or epididymal disease, heat stress | | Sperm viability | > 80% live | < 70% live | Necrospermia, handling damage | These values are adapted from the [Society for Theriogenology resources](https://www.therio.org/) and the [MSD Veterinary Manual](https://www.msdvetmanual.com/). They serve as clinical guides, not absolute thresholds. A dog with a total count of 90 x 10⁶ but excellent motility and morphology may still be fertile, while a dog with a count of 200 x 10⁶ and 40% progressive motility may not be. Interpret the panel as a whole. ## Decision Points and Repeat Evaluation A single abnormal ejaculate does not establish infertility. Repeat collection after 48 to 72 hours of sexual rest. Dogs with partial ejaculation, poor collection technique, or recent stress may produce a substandard sample that improves on the second attempt. The [retrospective study from the University of Pisa](https://pubmed.ncbi.nlm.nih.gov/29883842/) found that azoospermic samples resulted from both complete and incomplete ejaculations, distinguished by seminal alkaline phosphatase concentration. A low alkaline phosphatase level indicates incomplete ejaculation instead of true azoospermia, and the collection should be repeated. Age is a significant variable. The breeding facility study demonstrated that progressive motility was lower in senior males aged 7 years and older. When evaluating an older dog, compare results against age-matched expectations and discuss the age-related decline with the owner before pursuing advanced diagnostics. ## Documentation and Reporting Record the date, collection method, fraction volumes, color, and any complications during collection. Document motility as a percentage with the time of assessment. Record concentration, total count, and morphology with the specific abnormalities observed. Note the stain used and the number of spermatozoa counted. Include the interpretation and any recommendations for repeat evaluation or additional testing. The [American Veterinary Medical Association practice resources](https://www.avma.org/resources-tools) provide guidance on professional record-keeping standards. A structured report template improves consistency between evaluations and facilitates comparison over time, which is particularly valuable for stud dogs monitored across multiple collections. ## Structured Collection Checklist - Confirm the dog is healthy, free of systemic illness, and has had 48 to 72 hours of sexual rest. - Prepare the collection area: non-slip surface, quiet environment, and a teaser bitch in standing estrus if needed. - Assemble equipment: collection cone, graduated centrifuge tube, warmed slides, coverslips, stain, and a warmed microscope stage. - Allow the dog to mount and achieve penile erection. - Redirect the penis caudally through the hind leg once erection is achieved. - Apply gentle digital pressure behind the bulbus glandis to stimulate ejaculation. - Collect the first fraction separately, then switch tubes for the sperm-rich fraction. - Continue collection through the third fraction if total volume is needed for insemination. - Assess motility within 5 minutes of collection. - Measure concentration and prepare a morphology smear. - Record all findings in the medical record with the date and collection conditions. ## Recognized Complications and Failure Modes Manual collection is low risk, but complications do occur. The most common is incomplete ejaculation, where the dog emits only the sperm-poor presperm fraction or stops after the sperm-rich second fraction. The ejaculate is then reported as azoospermic or oligozoospermic when the testis is normal. Detect this early by measuring seminal alkaline phosphatase. A low concentration, below 5,000 IU/L, indicates prostatic or epididymal aplasia, retrograde ejaculation, or incomplete collection instead of testicular failure. Repeat the collection with a teaser bitch in standing oestrus and verify that all three fractions are obtained. The retrospective data from the University of Pisa show that azoospermic samples resulted from complete or incomplete ejaculations in roughly equal measure, and the distinction required alkaline phosphatase measurement and ancillary examination. Penile trauma is uncommon but occurs when the clinician grips too firmly behind the bulbus glandis or when the dog thrusts against an ungloved hand. Preputial laceration and balanoposthitis are the usual sequelae. Prevent this by maintaining a loose grip, using lubrication, and releasing immediately if the dog shows discomfort. Hemorrhage in the ejaculate, visible as fresh blood or a reddish tinge, should prompt a prostatic evaluation instead of immediate abandonment of the collection. Urine contamination is a frequent problem in excited or submissive dogs. It appears as a yellow discolouration and a pungent odour in an otherwise normal ejaculate. Urine is spermicidal, so motility will drop rapidly. Discard the sample and recollect after the dog has urinated and been allowed to settle. If contamination recurs, consider a two-person collection with one clinician occluding the prepuce while the other handles the penis. ## Common Errors and Corrective Actions Less experienced clinicians frequently misidentify the sperm-rich fraction. The first fraction is clear and watery, the second is milky and opaque, and the third is prostatic and again clear. Collecting the first and second fractions into a single tube dilutes the sperm-rich portion and makes concentration estimates unreliable. Use separate collection vials for each fraction and combine them only after the second fraction has been assessed. Overheating the sample is the most damaging error. A collection tube held in a closed fist or placed on a warm stage at 40°C or higher will kill sperm within minutes. Use a water bath set to 37°C and check the thermometer. Cold shock is equally harmful, do not place the sample on a cold metal surface or refrigerate it before evaluation. Subjective motility assessment is prone to inter-observer variation. A clinician who evaluates motility immediately after collection, before the sample has equilibrated, will record falsely low values. Allow the sample to sit at 37°C for 5 minutes before assessment. Compare your estimates against a computer-assisted sperm analyzer periodically if one is available, and calibrate against the reference values established in fertile populations. Morphology errors arise from poor staining technique. Eosin-nigrosin smears that are too thick or too thin create artefacts that mimic acrossomal defects. Prepare a standard smear, air dry it rapidly, and examine at 1,000x oil immersion. Count at least 100 spermatozoa and record defects by region: head, midpiece, and principal piece. ## Limitations of the Evidence The evidence base for canine semen evaluation is thinner than for other domestic species. The longitudinal study from Guide Dogs for the Blind tracked fertility in 39 Labrador retrievers and established reference values for that population, but the breed is overrepresented and the sample size is modest. Age effects on progressive motility were only significant in senior males, yet the senior group contained only five dogs, so the power to detect smaller age-related changes was limited. The retrospective study from Pisa included 140 dogs of varied breeds and sizes, but the reason for collection influenced semen quality, with lower normal sperm percentages in dogs presented for evaluation instead of for artificial insemination. This suggests that clinician expectation and collection technique, also testicular function, shape the results. Expert opinion still differs on the prognostic value of individual parameters. Total sperm count and progressive motility are widely accepted as the strongest predictors of fertility, but morphology thresholds vary between references. The Society for Theriogenology provides professional resources and consensus guidance on breeding soundness evaluation, and practitioners should consult these when local protocols differ. No single parameter reliably predicts pregnancy outcome, and the interaction between semen quality and female factors remains poorly characterized. ## Referral, Consultation, and Reporting Refer to a veterinary theriogenologist or a commercial canine reproduction laboratory when the ejaculate is persistently azoospermic despite complete collection, when morphology defects exceed 60% of spermatozoa, or when the dog is intended for a breeding program and the owner requires a formal fertility forecast. Specialist laboratories offer flow cytometric assessment of sperm chromatin structure, mitochondrial DNA copy number, and reactive oxygen species, tests that are not practical in general practice but that add prognostic information in selected cases. Regulatory reporting is rarely required for routine semen collection. If you suspect a notifiable infectious cause of orchitis or epididymitis, such as Brucella canis in endemic regions, consult the World Organization for Animal Health terrestrial animal health standards for current surveillance obligations. The American Veterinary Medical Association provides practice resources on professional conduct and record keeping that apply to breeding soundness examinations. The MSD Veterinary Manual offers peer-reviewed guidance on reproductive disease and diagnostic interpretation for cases that fall outside routine parameters. | Observation | Likely cause | Discriminating check | |---|---|---| | Clear ejaculate, no sperm | Incomplete collection | Seminal alkaline phosphatase below 5,000 IU/L | | Yellow ejaculate, rapid motility loss | Urine contamination | Odour, discolouration, recollect after urination | | Blood in ejaculate | Preputial or penile trauma, prostatic disease | Physical examination, prostatic palpation and ultrasound | | Low motility in fresh sample | Cold shock or overheating | Verify collection temperature, reassess after 5 min at 37°C | | High proximal droplets | Epididymal immaturity or recent ejaculation | Repeat collection after 48 h sexual rest | | Azoospermia with normal alkaline phosphatase | Testicular failure or obstruction | Testicular ultrasound, biopsy, hormonal assessment | ## Frequently Asked Questions ### How should I proceed when a teaser bitch is not available for collection? A teaser bitch in standing estrus is the most reliable stimulus, but experienced stud dogs will often mount a non-estrus female, a placid ovariectomized female, or even a stuffed surrogate. When no teaser is available, allow the male to urinate in the collection area first, then introduce a novel environment. Some males respond to the scent of estrus urine applied to a surrogate. If the male fails to mount after 5 to 10 minutes, stop the attempt and retry later. Repeated failed collections in a novel setting can create a conditioned aversion. For persistently reluctant males, consider collecting in the male's home kennel with the owner present. The [Society for Theriogenology](https://www.therio.org/) provides professional resources on managing collection difficulties in breeding soundness examinations. ### What is the minimum equipment set needed to perform a clinically useful semen evaluation? A functional minimum includes a collection cone and tube, a warm-water bath or warming block, a hemocytometer or counting chamber, a microscope with phase-contrast or bright-field optics, and a slide warmer. Eosin-nigrosin stain and clean glass slides are required for morphology and viability. A spectrophotometer or computer-assisted sperm analyzer is convenient but not essential, a hemocytometer provides accurate concentration when performed correctly. If a warming stage is unavailable, maintain the microscope in a warm room and work quickly, as cold shock degrades motility within seconds. The [MSD Veterinary Manual](https://www.msdvetmanual.com/) describes standard laboratory methods for semen assessment that can be adapted to minimal equipment. ### How do I distinguish a true azoospermic ejaculate from an incomplete collection? Measure seminal alkaline phosphatase (ALP) concentration. The canine epididymis contributes high ALP activity, so a sample with low ALP and no sperm indicates failure to collect the sperm-rich fraction. A complete ejaculate with true azoospermia will have normal or high ALP. In a retrospective study of 251 canine semen examinations, azoospermic samples were classified as complete or incomplete ejaculations based on seminal ALP concentration and ancillary examinations. If ALP testing is unavailable, repeat the collection after a 10-minute rest, a second attempt that yields sperm confirms the first was incomplete. Persistent true azoospermia warrants testicular ultrasound, palpation, and endocrine evaluation. ### What should I tell an owner when the stud dog's semen quality is below reference values? Frame the discussion around fertility potential, not absolute sterility. Explain that semen evaluation identifies subfertility but cannot guarantee pregnancy, and that a single poor sample does not confirm infertility. Present the specific parameters that fell below reference ranges, such as motility, morphology, or total sperm count, and explain what each parameter contributes to fertilization. Recommend a repeat evaluation in 3 to 4 weeks, since spermatogenesis in the dog takes approximately 60 days and transient insults can depress quality. Discuss management options, including timed artificial insemination with chilled semen, which may improve outcomes when semen quality is marginal. The [AVMA practice resources](https://www.avma.org/resources-tools) offer guidance on client communication in reproductive medicine. ### How should I handle a dog that ejaculates but produces no sperm-rich fraction? The sperm-rich second fraction is typically clear to opalescent and follows the initial urethral fraction. Some males, particularly young or excited dogs, may ejaculate only the first and third fractions. Observe the collection closely: the sperm-rich fraction usually appears as a sudden change in color and viscosity. If it is missed, the sample will be dilute with low concentration but normal total sperm count. Centrifugation can concentrate the sample for insemination. For repeated failure to collect the sperm-rich fraction, consider prostatic disease or retrograde ejaculation, though both are uncommon. A complete breeding soundness examination, including palpation and ultrasound of the prostate and testes, is indicated before assuming a collection technique problem. ### Can I use the same collection and evaluation protocol for other species? No. The canine protocol is species-specific in several respects. The dog's three-fraction ejaculate and the use of a teaser bitch differ fundamentally from feline collection, where electroejaculation or an artificial vagina under anesthesia is standard. The cat ejaculate is small in volume, which limits the diagnostic procedures that can be performed. Stallion collection uses an artificial vagina with a breeding phantom, and the evaluation thresholds differ substantially. Even within dogs, breed size affects semen volume and total sperm count, so reference values must be interpreted with the individual dog's size and age in mind. Consult species-specific references before applying any protocol outside its intended species. ## Related Clinical & Scientific Guides * [Diagnostic Approach to Canine Infertility in the Bitch](/knowledge/veterinary-medicine/theriogenology/diagnostic-approach-to-canine-infertility-in-the-bitch) * [Canine Neonatal Resuscitation: Protocol and Monitoring](/knowledge/veterinary-medicine/theriogenology/canine-neonatal-resuscitation-protocol-monitoring) * [Equine Breeding Soundness Examination of the Stallion](/knowledge/veterinary-medicine/theriogenology/equine-breeding-soundness-examination-of-the-stallion) ## References and Further Reading - [Semen evaluation and fertility assessment in a purebred dog breeding facility.](https://pubmed.ncbi.nlm.nih.gov/27658745/). 2017. - [Semen collection in cats: techniques and analysis.](https://pubmed.ncbi.nlm.nih.gov/16527340/). 2006. - [Variables affecting semen quality and its relation to fertility in the dog: A retrospective study.](https://pubmed.ncbi.nlm.nih.gov/29883842/). 2018. - [Semen collection by electroejaculation in the domestic cat.](https://pubmed.ncbi.nlm.nih.gov/730615/). 1978. - [The National Animal Germplasm Program: challenges and opportunities for poultry genetic resources.](https://pubmed.ncbi.nlm.nih.gov/16523615/). 2006. - [Effect of L-carnitine administration on the seminal characteriztics of oligoasthenospermic stallions.](https://pubmed.ncbi.nlm.nih.gov/15226028/). 2004. - [Society for Theriogenology Resources](https://www.therio.org/). Society for Theriogenology. - [MSD Veterinary Manual, Professional Edition](https://www.msdvetmanual.com/). MSD Veterinary Manual. - [American Veterinary Medical Association Practice Resources](https://www.avma.org/resources-tools). American Veterinary Medical Association. ## Related Articles - [Canine Neonatal Resuscitation: Protocol and Monitoring](/knowledge/veterinary-medicine/theriogenology/canine-neonatal-resuscitation-protocol-monitoring) - [Canine Semen Cryopreservation: Protocols and Fertility Outcomes](/knowledge/veterinary-medicine/theriogenology/canine-semen-cryopreservation-protocols-and-fertility-outcomes) - [Estrus Synchronization Protocols in Cattle: A Practical Guide](/knowledge/veterinary-medicine/theriogenology/estrus-synchronization-protocols-in-cattle-a-practical-guide) - [Breeding Soundness Examination of the Canine Male](/knowledge/veterinary-medicine/theriogenology/breeding-soundness-examination-of-the-canine-male) - [Canine Artificial Insemination: Techniques and Timing](/knowledge/veterinary-medicine/theriogenology/canine-artificial-insemination-techniques-timing) > This article is educational professional reference material for veterinary audiences. It is not a substitute for veterinary diagnosis, individual clinical judgment, current product labeling, or applicable regulatory requirements.