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Pyometra in dogs

Pyometra in dogs

Females are truly a force to be reckoned with. This includes our little female doggies too. Female reproduction is a complicated business which means that there are more opportunities for things to go wrong. One particularly nasty reproductive disease in females is called pyometra. It is a condition that is very painful and can potentially be deadly. Here are a few things to keep an eye out for in your dog in regards to pyometra.

What is pyometra?

Pyometra is a serious and potentially life-threatening condition that can affect female dogs. It is essentially a bacterial infection in the uterus, leading to the accumulation of pus. Pyometra typically occurs in unspayed dogs. It can be seen in spayed dogs as well, although it is much more rare.

There are two types of pyometra:

  1. Open Pyometra: In this form, the cervix remains open, allowing the pus to drain out. 
  2. Closed Pyometra: In this case, the cervix is closed, preventing the pus from draining. 

If left untreated, pyometra can be life-threatening. The uterus may rupture, leading to peritonitis, a severe infection in the abdominal cavity. The infection can also spread to other organs, causing septicemia (blood infection).

Surgery of pyometra (uterus infection) Dog in a veterinary surgery , Surgery of pyometra (uterus infection) pyometra dog stock pictures, royalty-free photos & images

What causes pyometra?

Pyometra in dogs is primarily caused by hormonal changes during the estrus (heat) cycle, combined with the presence of bacteria. See below for a few key factors that contribute to the development of pyometra:

Hormonal influence: 

The hormonal fluctuations that occur during the estrus cycle, specifically the rise and fall of progesterone levels, can lead to changes in the uterus. Progesterone promotes the thickening of the uterine lining, preparing it for potential pregnancy. This thickened lining provides an ideal environment for bacteria to grow if an infection occurs.

Bacterial infection: 

Bacteria, most commonly Escherichia coli (E. coli), are the primary culprits in causing pyometra. These bacteria can enter the uterus through the cervix during the receptive phase of the estrus cycle. The presence of progesterone, which relaxes the cervix, makes it easier for bacteria to enter and establish an infection. Once inside the uterus, bacteria multiply, leading to the accumulation of pus.

Uterus wall consist pyometra with cervicitis, photomicrograph show dense infiltration of polymorphs, lymphocytes, histiocytes and necrotic material. Uterus wall consist pyometra with cervicitis, photomicrograph show dense infiltration of polymorphs, lymphocytes, histiocytes and necrotic material. pyometra dog stock pictures, royalty-free photos & images

Unspayed status:

Pyometra is almost exclusively seen in intact (unspayed) female dogs. The risk increases with age as the uterus becomes more susceptible to infections over time. The longer a female dog goes through heat cycles without being spayed, the higher the likelihood of developing pyometra.

Other factors that may contribute to the development of pyometra include a previous history of uterine infections, certain medications that influence hormone levels, and underlying conditions that compromise the immune system.

What are the symptoms of pyometra in dogs?

The symptoms of pyometra in dogs can vary depending on whether the condition is open or closed, as well as the severity of the infection. Here are the common signs to look out for:

  • Vaginal discharge: 

A pus-like or bloody discharge from the vulva is a characteristic symptom of pyometra. The discharge may be seen as a continuous drip or a noticeable stain on bedding or the dog's rear end.

  • Increased drinking and urination: 

Dogs with pyometra may exhibit increased thirst and urination as the body tries to eliminate toxins and maintain hydration.

  • Lethargy and depression: 

Dogs affected by pyometra often show signs of general weakness, fatigue, and a lack of energy. They may appear less active and may be reluctant to participate in usual activities.

  • Loss of appetite

A decreased or complete loss of appetite is common in dogs with pyometra. They may show disinterest in food or may eat significantly less than usual.

  • Swollen abdomen: 

In closed pyometra cases, the infected uterus fills with pus, causing the abdomen to appear distended or swollen. This symptom is not always present or easily noticeable, especially in early stages or if the dog has a small or deep-set abdomen.

  • Vomiting and diarrhea: 

Some dogs may experience gastrointestinal symptoms such as vomiting and diarrhea. These symptoms can occur due to the body's response to the infection or the release of toxins.

  • Increased thirst and panting: 

Dogs with pyometra may pant excessively or exhibit increased respiratory rate due to the body's efforts to cool itself down. This can be accompanied by increased water consumption.

  • Fever: 

Although not always present, pyometra can cause an elevated body temperature. A dog with pyometra may have a fever, often accompanied by other signs of illness.

It is important to note that some dogs may show only mild symptoms or exhibit no visible signs at all, especially in the early stages of the condition. Therefore, any unspayed female dog showing abnormal behavior or physical changes should be examined by a veterinarian to rule out or diagnose pyometra or other potential health issues.

How is pyometra treated?

The treatment for pyometra in dogs typically involves prompt veterinary intervention and may include the following steps:


If the dog is in a critical condition or shows signs of dehydration or shock, immediate stabilization is necessary. This may involve intravenous fluid therapy, antibiotics, and other supportive care to stabilize the dog's vital signs and overall condition.


The primary treatment for pyometra is surgical removal of the infected uterus, which is known as an ovariohysterectomy or spaying. This procedure involves the complete removal of the uterus and ovaries. It is typically recommended even if the dog's condition appears stable because pyometra can rapidly worsen and become life-threatening.

Cleansing a sutured wound with antiseptic at the abdomen of a Border Collie after surgical removal of the uterus following a case of pyometra. Emergency surgery is needed to remove the uterus from dogs afflicted by pyometra which is an infection of the uterus. If the uterus is not surgically removed following infection then it will invariably lead to sepsis in which the dog can die. Here the wound is cleaned after five days following surgery. pyometra dog stock pictures, royalty-free photos & images


Prior to and following surgery, a course of broad-spectrum antibiotics is typically administered to combat the bacterial infection associated with pyometra. The specific antibiotics and duration of treatment will be determined by the veterinarian based on the severity of the infection and the dog's overall health.

Postoperative care

After surgery, the dog will require postoperative care and monitoring. This may include pain management, wound care, administration of antibiotics, and ensuring the dog is eating, drinking, and eliminating waste normally. The veterinarian will provide instructions on how to care for the dog during the recovery period.

It is important to note that the surgical removal of the infected uterus is the most effective and commonly recommended treatment for pyometra. Medications alone cannot effectively treat pyometra, and delay in treatment can lead to complications and increase the risk to the dog's life. Early detection and intervention greatly improve the chances of a successful recovery.

How to prevent pyometra

The most effective way to prevent pyometra in dogs is through spaying, which is the surgical removal of the uterus and ovaries. Spaying, also known as an ovariohysterectomy, eliminates the risk of developing pyometra and offers several other health benefits for female dogs. Here's what you need to know about preventing pyometra:


Spaying your female dog before she goes through her first heat cycle is the most recommended preventive measure against pyometra. Spaying removes the uterus and ovaries, eliminating the hormonal changes that contribute to the development of the condition. It completely eliminates the risk of pyometra and significantly reduces the risk of other reproductive-related health issues, such as mammary tumors and uterine infections.


The ideal time to spay a female dog is typically before her first heat cycle, which usually occurs between six to nine months of age. However, spaying can still be performed at any age, even if your dog has already gone through heat cycles. It's best to consult with your veterinarian to determine the most appropriate timing for spaying based on your dog's individual health and circumstances.

Veterinary Consultation

Schedule a consultation with your veterinarian to discuss the benefits, risks, and optimal timing for spaying your dog. They will assess your dog's overall health and provide guidance specific to your dog's breed, age, and any other relevant factors.

Responsible Breeding

If you plan to breed your dog in the future, it's essential to work with an experienced and responsible breeder who can help manage your dog's reproductive health. Breeding should only be undertaken by knowledgeable individuals who prioritize the health and well-being of the dogs involved.

It's important to note that while spaying is the most effective preventive measure, it is not without risks or potential complications. However, the risks associated with spaying are generally low compared to the potential risks and complications of pyometra. Your veterinarian can provide more information about the spaying procedure and address any concerns you may have.

Regular veterinary check-ups, maintaining proper hygiene, and a healthy diet and lifestyle can also contribute to your dog's overall health and reduce the risk of various health conditions, including pyometra.

Scruffy dog laying on floor, looking sad
Scruffy dog laying on floor, looking sad

View Sources

"Pyometra in Small Animal Theriogenology" by Margaret V. Root Kustritz (Chapter 13),Small Animal Theriogenology, 2nd Edition

"Pyometra: Diagnosis and Treatment Options" by Mary McLoughlin and Domenico Ventrella, Veterinary Clinics: Small Animal Practice, Volume 47, Issue 4, Pages 797-809

"Pyometra" by T. J. McCarthy, The Veterinary Clinics of North America: Small Animal Practice, Volume 40, Issue 5, Pages 1091-1105

"Pyometra" by Roberta Sartorelli, Veterinaria, Volume 34, Issue 3, Pages 13-23

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February 20, 2024
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