Breeding, Reproductive Health Advice

Stud Dog Issue: Blood in a Dog’s Semen

Why would a male dog drip blood? It is beneficial to look at the male’s semen in advance of a planned breeding to make sure there are no underlying issues in your stud dog. Some dog breeders want to plan a “clean out” ejaculation. The benefits to this are two-fold. First, you can eliminate some of the aging sperm that has been hanging around in the epididymis (the semen storage part of the testes). This is probably not necessary as there is a natural cycling of semen through the epididymis. Dogs have a way of taking care of this themselves.

Secondly, you can do a semen analysis. If the semen is not healthy looking, you will still have time to find another male. You need to avoid collecting and discarding the semen too close to the time of the dam’s ovulation. Some males, particularly males over five years of age do not make new sperm as quickly as they did when they were younger. Discarding the semen the night before the planned breeding can cause depletion of the last precious sperm, leading to an inadequate amount and a missed pregnancy.

Dog Semen Analysis

Your reproductive veterinarian can help you with this. There are five components of a semen analysis.

  1. Sperm count – the number of sperm in the ejaculate, done with a microscope or a sperm counter at your reproductive veterinarian’s clinic. Just seeing sperm does not give an assessment of fertility. We expect to see 10 million sperm per 10 pounds of body weight of the stud dog.
  2. Sperm morphology – the shape of the sperm. Each sperm should have a head with a cap (acrosome), neck and tail. There are many abnormalities that can be assessed using a microscope.
  3. Sperm motility – the movement of the sperm. With the correct concentration, a microscopic evaluation can assess if the sperm are progressively moving in a forward direction. Sperm that swim in circles don’t get the job done.
  4. Other cells in the ejaculate – red blood cells usually indicate either trauma to the penis or prostate disease (benign prostatic hypertrophy or hyperplasia) or white blood cells indicating an infection.
  5. Sperm longevity – adding extender to the ejaculate, keeping the sample refrigerated, and looking at how many sperm swim when they warm up will help indicate how long the sperm will live in the dam’s reproductive tract. This correlates with fertility.

Dog Prostate Issues or Injury

When collecting semen, you first get the pre-seminal fraction which is usually clear. Then you get the second sperm fraction which should be milky white, and third, the prostatic fraction which adds volume to semen and pushes the sperm forward. The prostatic fraction is the last fraction given and is put in during the tie. In the case of a prostate issue or infection, this fraction often contains blood.

Injury, usually from fighting, is another cause of blood in a dog’s semen. However, this is usually temporary and we worry more about scar tissue in the testicle than infection. When dogs come into heat, they can become grouchy. Some will snap or fight with friends that they normally get along with. If a male dog gets bit, we need to prevent any infection, especially if the scrotum is damaged. These males should be started on an antibiotic and monitored to be sure they recover.

Also, females in season cause males to become very stressed and will pace, pant, tear at fencing and can fight. Males can injure themselves trying to get to the female.


When diagnosing the cause of blood in the semen, first we rule out Brucellosis for our own peace of mind.

  • If the testicle itself is sore, Brucellosis must be ruled out. Often the RAST test is ran in the clinic to confirm Brucellosis negative.
  • Examine the scrotum for any signs of trauma or damage. These males must be monitored to be sure they recover without infection.
  • On males five-years-old or older, the vet will do a rectal exam and feel for prostate enlargement and tenderness. An enlarged prostate is common in dogs over age five. This can easily be treated using finasteride, a prescription drug available from your veterinarian. Ultrasound of the prostate is the most accurate way to diagnose benign prostatic hypertrophy/hyperplasia (BPH). With BPH, the prostate enlarges and becomes filled with small cysts, too small to feel with a finger on rectal exam but very obvious with ultrasound. If this is diagnosed, finasteride should be used. This will shrink the prostate and eliminate these cysts. If BPH is not treated, these little cysts, like the holes in Swiss cheese, will be invaded by bacteria, leading to an infection called prostatitis. Male dogs with prostatitis can get very sick, as sick as females with pyometra.
  • Lastly, your vet will examine the semen for blood, bacteria, and white blood cells, indicating infection as a cause.


Antibiotics should only be used if an infection is known to be present. Routine use of antibiotics in normal dogs will lead to resistant bacteria. Most dogs with enlarged prostates need finasteride, not antibiotics. Blood dripping from the penis is the sign of benign prostatic hyperplasia/hypertrophy (BPH), not an infection. Do NOT reach for antibiotics for BPH. BPH tends to flare up cyclically when dams in the kennel are in heat. Many veterinarians and breeders will start their dogs on antibiotics at this time. The blood goes away, which makes it look like the antibiotics were successful. In reality, the blood will disappear when the dams go out of heat. Use finasteride, daily, not just during heat cycles, to keep the male’s semen quality high.

If an infection is confirmed, only then should treatment with antibiotics be initiated. If your veterinarian confirms an infection in the prostate, called prostatitis, both an antibiotic and finasteride should be used. We usually recommend long-term antibiotics for four weeks and then re-evaluate the semen for blood and fertility. Trimeth-sulfa or Enrofloxacin (Baytril) are your best choices for antibiotics. If these fail, a culture of the ejaculate may be needed. Once cleared, relapses of prostate issues are common so monitor for reoccurrence. It is not enough to just have semen; we want these males to have normal numbers of sperm and no blood in any of the collection.

If you have cleared the blood in the semen but are still seeing low sperm count, give Breeder’s Edge Oxy Stud to support fertility and semen production. I prefer to keep them on Oxy Stud while treating; males are a valuable resource, and we want full recovery. Many sperm are needed to fertilize one egg. Breeder’s Edge Problem Male is another male health support option. The herbs and roots in this supplement have been found to be beneficial to a breeding male’s reproductive system.

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Keeping sperm counts high fertilizes all the eggs and is the key to normal litter size! If you need help, call us at 800.786.4751.

Article originally written by Donald Bramlage, DVM, Revival’s Former Director of Veterinary Services. This article has been updated/reviewed by Dr. Greer.

Written by: Marty Greer, DVM

Director of Veterinary Services

Marty Greer, Doctor of Veterinary Medicine, has 40+ years’ experience in veterinary medicine, with special interests in canine reproduction and pediatrics. She received her Doctor of Veterinary Medicine from Iowa State University in 1981. She’s served as Revival’s Director of Veterinary Services since 2019. In 2023, Dr. Greer was named the Westminster Kennel Club Veterinarian of the Year.

If you need help, call us at 800.786.4751.