Female and Male Reproductive Diseases in Horses

Horses

Female Reproductive Diseases

Pregnancy Disorders
Overview of Female Reproductive Diseases

  • Contagious Endometritis

  • Abortions

  • Dystocia

  • Equine Metritis

  • Retained Placenta

  • Rectal Tear

Abortions

  • Definition: Loss of embryo or fetus.
      - Can occur due to a variety of causes:
        - Bacterial Causes:
          - Common species include:
            - E. coli
            - Salmonella spp.
            - Klebsiella spp.
            - Actinobacillus spp.
        - Viral Causes:
          - Primarily due to:
            - Equine herpesvirus type 1
          - Typically occurs during the last trimester, often affecting multiple mares on the same farm.
        - Fungal Causes
        - Other Causes:
          - Twinning
          - Hormonal deficiencies
          - Congenital anomalies
          - Ergot alkaloid toxicity
          - Ingestion of tent caterpillar setae.

Clinical Signs of Abortions

  • Loss of fetus

  • Discharge from the vulva

  • Mare returns to estrus cycle

  • Premature milk letdown
      - Can require medical intervention such as fetotomy (manual removal of the fetus).

Diagnosis of Abortions

  • Bacterial Culture and Sensitivity

  • Virus Isolation

  • Fungal Culture

Treatment of Abortions

  • For Bacterial Infections:
      - Uterine flush with antibiotics
      - Systemic antibiotics

  • For Viral Infections:
      - Vaccination with a killed vaccine at 5, 7, and 9 months of gestation.

Dystocia

  • Definition: Difficulty during parturition (birth).
      - The second stage of labor (the period from when the amniotic sac ruptures to the delivery of the foal) should not exceed 20 minutes.
      - Dystocia appears to occur more frequently in maiden mares (first-time mothers).
      - Common causes of dystocia include:
        - Mare/foal size mismatch
        - Malpresentation of the foal
        - Presence of twins.

Common Causes of Calving Difficulty

  • Normal Presentation:

  • Posterior Presentation:

  • Transverse Presentation:
      - Legs first
      - Back first
      - Head back
      - Head to the side
      - Head down
      - Shoulder flexion
      - Carpal flexion
      - Upside down (abnormal presentations)
      - Hock flexion
      - Hip flexion.

Clinical Signs of Dystocia

  • Initial rush of amniotic fluid, followed by no foal after 20 minutes

  • Straining with no progress in delivery.

Treatment of Dystocia

  • Correct position of foal in the birth canal.

  • If foal is determined to be dead on vaginal examination:
      - Fetotomy or cesarean section may be necessary.

Contagious Equine Metritis

  • Definition: Highly contagious disease caused by Taylorella equigenitalis, a Gram-negative bacterium.
      - Transmitted from stallion to mare during breeding.
      - Disease has been eradicated from the United States.

Clinical Signs of Contagious Equine Metritis

  • History of infertility.

  • 10-14 days after breeding, copious mucopurulent discharge from vulva appears.

  • Discharge typically stops within 2 weeks, but mares can become inapparent carriers.

Diagnosis of Contagious Equine Metritis

  • Bacterial culture and sensitivity tests

  • Collect samples from:
      - Clitoral fossa from female.
      - Urethral fossa and diverticulum from male.

Treatment of Contagious Equine Metritis

  • Wash affected areas once daily for 1 week with chlorhexidine scrub.

  • Antibiotics may not be effective.

Endometritis

  • Definition: Infection of the uterine endometrium, a common cause of poor fertility in mares.

  • More frequently seen in older mares, those that have had many offspring, and maiden mares.

  • Underlying Causes:
      - Repeated breedings.
      - Chronic infections.
      - Poor vulvar conformation.
      - Sexually transmitted diseases.
      - Age-related degeneration.

Clinical Signs of Endometritis

  • Failure to conceive.

  • Possible vulvar discharge.

  • Fluid accumulation in the uterus.

Diagnosis of Endometritis

  • Culture and sensitivity testing.

  • Ultrasound examination.

  • Uterine biopsy.

Treatment of Endometritis

  • Uterine lavage with antibiotics.

  • Administer oxytocin to help manage the lining issue from post-breeding veterinary treatments.

Retained Placenta

  • Definition: A condition where the full placentas are not passed within 3-6 hours after foaling.

  • Most commonly noted in mares with a history of dystocia.

Clinical Signs of Retained Placenta

  • History of dystocia.

  • Placental membranes seen protruding from the vulva after 3 hours.

  • Vaginal discharge if a small remnant of the placenta remains in the uterus for days.

  • Potential for laminitis to develop after 48 hours.

  • Possible systemic signs of illness.

Diagnosis of Retained Placenta

  • Palpation of uterus and placenta through the vulva.

  • Visualization of placental remnants.

Treatment of Retained Placenta

  • Administer oxytocin to assist uterine contractions and expulsion of contents.

  • Uterine lavage may be necessary.

  • Gentle traction may be needed to facilitate expulsion.

  • Flunixin meglumine (Banamine) can be administered to bind endotoxins.

  • Systemic antibiotics may be required.

Rectal Tears

  • Definition: A condition most commonly seen in mares that have just foaled or those that have been recently rectally palpated.
      - Every time a mare is palpated, there is a risk for a rectal tear.
      - During foaling, the foal's foot can penetrate the vagina or uterus leading to perforation.
      - Rectal tears are graded I-IV based on severity.

Clinical Signs of Rectal Tears

  • Presence of blood on sleeve after palpation.

  • Signs of colic.

  • Septicemia which can lead to death.

  • Foal foot may penetrate the rectum during birth.

Treatment of Rectal Tears

  • Surgical correction if necessary.

  • Referral to a specialized hospital facility is critical.

  • Systemic antibiotics should be administered.

  • Flunixin meglumine may provide pain relief and reduce inflammation.

  • Intravenous fluids may be required based on the severity of the condition.

  • Packing of the rectum and administering wet soft feeds can help with recovery.

Neoplasia

Neoplasia Overview

  • Ovarian Cell Tumors: The most common neoplastic disorder in female horses.
      - Generally benign, steroid-producing growths.

Ovarian Cell Tumor Clinical Syndrome

  • Tumors arise on the ovary:
      - If predominantly granulosa cells are involved: Excess estrogen is produced with little progesterone secreted.
      - If predominantly thecal cells are involved: Excess testosterone is produced.

Clinical Signs of Ovarian Cell Tumors

  • Persistent estrus (related to granulosa cell involvement).

  • Anestrus may occur.

  • Aggressive behavior (associated with thecal cell involvement).

  • Mares may experience pain when handled or ridden.

Diagnosis of Ovarian Cell Tumors

  • Ultrasound assessment is utilized.

  • Rectal palpation may reveal an enlarged affected ovary.

Treatment of Ovarian Cell Tumors

  • Surgical removal of the affected ovary is the primary treatment.

  • It is uncommon to perform a spay unless symptoms manifest.

Male Reproductive Diseases

Male Reproductive Disorders Overview

  • Testicular Disorders: Cryptorchidism

  • Penile Disorders

  • Neoplasia

Testicular Disorders

  • Cryptorchidism: A condition where one or both testicles fail to descend into the scrotum.
      - Testicles should typically descend by 6 months of age but may take up to 2 years in some cases.
      - There is a strong genetic link, and affected horses should not be bred.

Treatment of Cryptorchidism

  • Abdominal surgery is necessary to remove the retained testicle.

  • It is unethical to remove the descended testicle while leaving the retained one in place.

Penile Disorders
Penile Paralysis

  • Definition: A condition where the penis drops and does not retract.
      - Causes may include:
        - Administration of acepromazine.
        - Damage to third and fourth sacral nerves.
        - Certain neurologic diseases (e.g., rabies, EHV-1).
        - Trauma.

Clinical Signs of Penile Paralysis

  • The penis drops and fails to retract.

  • The stallion does not achieve an erection.

  • A portion of the penis distal to the sheath becomes edematous and swollen.

Treatment of Penile Paralysis

  • Address underlying causes of the paralysis.

  • Hydrotherapy and diuretic such as furosemide may be administered.

  • Penile amputation may be an option in severe cases.

  • Avoid the use of acepromazine in stallions and geldings due to its side effects.

Neoplasia Associated with Male Horses

  • Neoplasia Overview:

  • Penile Tumors: Common types include squamous cell carcinoma and benign sarcoids, which appear warty in appearance.