Thu, 04/06/2023 - 9:08pm

Taking Up a Collection

Sperm abnormalities and semen sorting

My dog was collected, and the sperm was abnormally shaped. What would cause that?


Evaluation of the size and shape of sperm is an important part of the collection procedure, whether the collection is for immediate insemination, freezing for future use or simply assessment for fertility. Once the semen has been collected, a detailed analysis is performed. The color, quantity and amount are recorded. The semen is examined for several attributes: morphology, speed, motility, quantity, concentration and cellularity.

Motility is the speed and forward motion of the sperm cell. Quantity is the sperm count of live sperm cells. Concentration is the density of the sample — concentrated versus moderate or dilute. Cellularity describes the presence of other cells, including white blood cells, red blood cells, epithelial cells or bacteria.

The answer to this week’s question concerns morphology, which is the appearance of the sperm cells and any abnormalities present. Teratozoospermia is the term for the reproductive disorder characterized by the presence of abnormal sperm. With this disorder, 40 percent or more of the sperm are abnormally shaped.

The effect of abnormal sperm on fertility is questionable, but optimal fertility requires at least 80 percent morphologically normal spermatozoa. It is nearly impossible for sperm that are abnormally shaped to fertilize an egg.

This condition can affect dogs of any age, but older dogs are more likely to have age-related diseases or conditions that affect overall sperm quality. There is no breed predilection.

Spermatozoal abnormalities are classified into primary and secondary defects. Primary defects are associated with the production of sperm in the testes. This process is called spermatogenesis. Secondary abnormalities arise during the maturation, transport and storage within the epididymis, which is part of the spermatic duct system.

Defects found in the heads of sperm cells, such as small heads, double heads or large heads, and mid-piece and tail deformities such as droplets, split tails, short tails and curled tails, are all problems associated with the actual production of the sperm. Other abnormalities, such as detached heads and bent tails, occur during the transport of the sperm cells.

Often there are no outward symptoms of teratozoospermia. The most obvious sign is a dog that fails to impregnate his breeding partner.


What are the causes of teratozoospermia?


The causes of this condition fall into two categories: There are congenital causes, which means the dog was born with the condition, and acquired causes, which means other outside factors affected the sperm. Acquired causes are often treatable so that normal sperm morphology can be restored.

Fucosidosis is one of the congenital conditions. It is a metabolic disorder caused by a deficiency of the enzyme fucosidase, which breaks down the sugar fucose. Dogs with this deficiency have been found to have an associated abnormality in their ability to produce and develop normally formed sperm. English Springer Spaniels have an autosomal recessive inheritance pattern, and, obviously, only males are affected by the condition.

Another congenital condition is primary ciliary dyskinesia (PCD). Cilia are hair-like cells, and dyskinesia is the term for difficulty performing voluntary movements. The cilia cells help move the sperm through the tubules in the testicles. Dogs with PCD have no movement of the ciliated cells or the movement is abnormal. Since the sperm do not make their way through the spermatic ducts, the dog is infertile. Genetically, this is thought to be an autosomal recessive trait.

Small, underdeveloped testicles will also produce abnormal sperm. This condition is idiopathic, which means its cause is unknown.

Acquired conditions are things that affect normally developed testes. These can include trauma, elevated temperature from the environment or a prolonged fever, obesity or exercise-induced heat exhaustion.

Infections of the reproductive tract, including prostatitis, brucellosis, orchitis (inflammation of the testes) and epididymitis (inflammation of the ducts through which the sperm travel), will result in abnormal sperm morphology.

Certain drugs, such as the chemotherapy drugs vincristine and cyclophosphamide, the antibiotic tetracycline and the anti-fungal ketoconazole, will have a negative impact on male fertility. Tumors of the testes can destroy the structure of the testes and affect the appearance of the sperm.

Intact male dogs that are going to be used in a breeding program should be collected on a regular basis to ensure the sperm that is stored is refreshed often.


Is there treatment for teratozoospermia?


The specific treatment would depend on the underlying disease or condition. Antibiotics and anti-inflammatory medications would be prescribed for infectious diseases and swelling due to inflammation. Removal of one testicle may be recommended for unilateral testicular tumors.

If it is the summer season or your dog is in an extremely hot environment, make sure he is housed in a cooler space. In addition, alter your dog’s exercise program to reduce heat stress. Obese dogs need diet management as well as exercise, but caution needs to be used so they do not overheat.

Rest and a break from breeding is the treatment for trauma to the testes. On the other hand, frequent semen collection may improve the semen quality in dogs with idiopathic teratozoospermia. In both cases, the semen should be evaluated before it is used for breeding. In cases due to reversible causes, a complete improvement in sperm morphology does not usually occur before 60 days, which is the approximate length of a complete spermatogenic cycle.


Is there a way to select for more male or female puppies in a litter?


Over the years I have heard many “tried and true” methods for producing more puppies of a desired sex in a litter. Actually, I have just had a client who wanted only males, since he felt they were better performers in the show ring. Everyone else seems to want to increase the number of female puppies.

Some of these strategies included performing the insemination with the bitch facing east and giving large doses of vitamin C before breeding. Whether it is coincidental or whether these tactics work, it doesn’t hurt to try them.

However, there are actual scientific methods to sort sperm based on their DNA. Basic genetics tells us that the female provides X chromosomes and the male provides either an X or a Y chromosome. Together XX will make a female and XY will make a male of the species.

Effective preselection of either male or female offspring by separation of X- or Y-chromosome-bearing spermatozoa has been accomplished in several species of livestock, companion animals and also in humans. A flow cytometric sperm-sorting method, which measures the DNA content of the sperm, is used.

The effectiveness of utilizing DNA content differences between the X and Y chromosome in sperm depends not only on relative differences in the DNA but also on the ability to precisely orient these sperm at the time of measurement. Sperm cells with flattened and oval heads tend to be more readily oriented in a sperm sorter than those sperm with more rounded or angular heads. Canine sperm have flattened, oval-shaped heads, which makes the sorting process easier and more accurate.  

The are some non-prescription products available for purchase described as “canine sexing agents.” They come in a male and female form. The vial of fluid is added to fresh, chilled or frozen semen before the semen is inseminated.

The female product works by enhancing the fertility of the sperm bearing the X chromosome while reducing the motility of the Y-chromosome-bearing sperm. The female to male ratio is reported to be boosted by 20 to 30 percent. The male agent works in the same way, just boosting the Y-chromosome-carrying sperm.

This interesting technology continues to evolve, making the process of predetermining the sex of puppies in a litter possible.



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