Histiocytoma in Dogs

icon March 26, 2024

Histiocytoma in dogs is a topic that concerns many pet owners, especially when they discover unfamiliar growths on their beloved companions. Understanding what histiocytomas are, how they can affect your dog, and the options available for treatment and management is essential for any dog owner. This article aims to provide a comprehensive overview of histiocytomas in dogs, covering their causes, symptoms, diagnosis, treatment, and prognosis.

What is A Histiocytoma in A Dog?

Histiocytomas are benign (non-cancerous) tumors that commonly occur in dogs. They are a type of skin tumor that arises from the Langerhans cells, which are part of the dog's immune system and reside in the skin. Histiocytomas are most often seen in young dogs, typically less than three years of age, but they can appear in dogs of any age. These tumors are usually small, round, and raised, and they may appear red and ulcerated.

Histiocytoma in Dogs

Symptoms of Histiocytoma in Dogs

Histiocytomas typically present as small, solitary, hairless, and fast-growing nodules on the skin. They are most commonly found on the head, neck, ears, and limbs of dogs. While these tumors are usually not painful, they can become ulcerated and may bleed or become infected, which could cause discomfort to the dog.

What Causes Histiocytoma in Dogs?

Histiocytomas in dogs are benign skin tumors that are relatively common, particularly in young dogs. The exact cause of histiocytomas is not fully understood, but they are believed to result from an abnormal proliferation of histiocytes. Histiocytes are a type of immune cell that reside in the skin and other tissues, where they play a role in the immune response by engulfing foreign material and debris.

Several factors may contribute to the development of histiocytomas in dogs:

  • Genetic Factors: Some dog breeds appear to be more predisposed to developing histiocytomas, suggesting a genetic component. Breeds such as Boxers, Bulldogs, Scottish Terriers, and Greyhounds are often mentioned as being at higher risk.
  • Immune System Activity: Since histiocytomas are composed of immune cells, there is speculation that aspects of the dog's immune system might influence their development. They might arise in response to unknown stimuli that cause histiocytes to proliferate excessively.
  • Age: Histiocytomas are most commonly seen in dogs less than 3 years old, suggesting that age and the maturation of the immune system might play a role in their development.
  • Environmental Factors: While less documented, environmental influences could potentially contribute to the emergence of these tumors, although there is no concrete evidence to support this theory.

Histiocytoma in Dogs

How to Treat Histiocytoma in Dogs?

The treatment of histiocytoma in dogs often depends on the tumor's characteristics, such as its size, location, and whether it's causing discomfort to the dog. Many histiocytomas may resolve on their own without any treatment within a few weeks to a few months, as they are benign tumors. However, intervention might be necessary in some cases. Here are the common approaches to treating histiocytomas in dogs:


  • Watchful Waiting: Since many histiocytomas will regress on their own, a common approach is simply to monitor the tumor for changes in size or appearance. This is often recommended if the tumor is not causing any discomfort or issues for the dog.

Surgical Removal

  • Surgery: If the histiocytoma is growing, causes discomfort, becomes infected, or does not regress on its own after a reasonable period, surgical removal may be recommended. Surgery is typically straightforward and can often be performed under local anesthesia, depending on the tumor's size and location.


  • Topical Treatments: In some cases, especially if there's any sign of infection, topical treatments such as antibiotics or corticosteroids may be applied to the tumor.
  • Systemic Medications: Although less common for histiocytomas, systemic medications like corticosteroids may be considered in specific cases, particularly if the tumor is causing significant discomfort or if there are multiple tumors.
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Alternative Treatments

  • Cryotherapy: For smaller tumors, cryotherapy, which involves freezing the tumor with liquid nitrogen, may be an option. This method is less invasive than surgery and can be effective, although it may require multiple sessions.
  • Laser Therapy: Laser therapy is another less invasive option that can be used to remove or reduce the size of the tumor. It's particularly useful for tumors in sensitive areas where surgery might be more complicated.

Monitoring and Follow-Up

  • Regular Check-Ups: Whether the tumor is treated or left to regress naturally, it's important to have regular veterinary check-ups to monitor its progress and ensure it hasn't become malignant or caused other health issues.

Histiocytoma Healing Stages

The healing process of a histiocytoma in dogs generally progresses through several stages, especially if the tumor resolves on its own, which many do. Here's a general overview of what you might expect during the healing stages of a histiocytoma:

1. Development Stage

  • Appearance: Initially, a histiocytoma appears as a small, raised, and often pinkish or red lump on the skin. It might have a smooth, dome-shaped appearance.
  • Growth: These tumors can grow quickly over a few weeks, often reaching a certain size and then stabilizing.

2. Plateau Stage

  • Stability: After reaching its full size, the histiocytoma might not change much for a while. This plateau phase can vary in duration but typically lasts a few weeks.
  • Observation: During this time, the tumor is closely monitored for any changes in size, shape, or behavior (such as ulceration or infection).

3. Regression Stage

  • Beginning of Regression: You may start to notice the tumor becoming less red and starting to shrink in size. The surface of the tumor might change, becoming drier or forming a scab.
  • Continued Shrinkage: The tumor continues to decrease in size, and the overlying skin may wrinkle or fold as the underlying tissue diminishes.

4. Resolution Stage

  • Final Healing: Eventually, the tumor may disappear completely, leaving behind either normal-looking skin or possibly a small patch of thinner or slightly discolored skin.
  • Scarring: In most cases, histiocytomas heal without significant scarring, especially if they have not been ulcerated or infected during their growth.

5. Monitoring

  • Post-Regression Observation: Even after a histiocytoma has healed, it's important to keep monitoring the area and the dog's overall health. Rarely, new tumors might appear, or there could be other changes in the dog's skin health that warrant veterinary attention.


Can Histiocytomas in Dogs Resolve on Their Own? 

Yes, histiocytomas in dogs often resolve on their own without any treatment. These benign tumors can undergo spontaneous regression, typically within a few weeks to a few months. The immune system of the dog recognizes the tumor cells as abnormal and eliminates them, leading to the resolution of the tumor.

Are There Any Home Remedies for Treating Histiocytomas in Dogs? 

While there's no scientifically proven home remedy to treat histiocytomas, maintaining overall skin health can support the natural healing process. This includes keeping the affected area clean and monitoring for changes. However, it's crucial not to apply any substances or concoctions without veterinary approval, as some could cause irritation or allergic reactions, potentially worsening the condition. Always consult a veterinarian before trying any home remedies.

Can Histiocytomas in Dogs Be Cancerous? 

Histiocytomas are benign, meaning they are not cancerous and do not metastasize (spread) to other parts of the body. However, there are other types of histiocytic diseases in dogs, such as malignant histiocytosis, which are cancerous and more serious. Therefore, any new skin growth should be evaluated by a veterinarian to ensure an accurate diagnosis.

Is Surgical Removal the Only Treatment Option for Histiocytomas in Dogs? 

No, surgical removal is not the only treatment option for histiocytomas in dogs. Given that many histiocytomas resolve on their own, a watch-and-wait approach is often recommended. If intervention is necessary due to the tumor's location, and size, or if it's causing discomfort, other treatments like cryotherapy (freezing) or laser therapy might be considered as less invasive options.

Can Histiocytomas in Dogs Cause Discomfort or Pain? 

Histiocytomas can cause discomfort or pain if they are located in areas where they might be irritated by scratching, chewing, or rubbing. Additionally, if the tumor becomes ulcerated or infected, it may be painful or bothersome to the dog. Otherwise, many histiocytomas are not painful and do not bother the dog.

Are Certain Dog Breeds More Predisposed to Histiocytomas?

Yes, certain dog breeds appear to be more predisposed to developing histiocytomas. Younger dogs and breeds such as Boxers, Bulldogs, Scottish Terriers, Greyhounds, and Labrador Retrievers are often mentioned as having a higher incidence of these tumors. However, histiocytomas can occur in any breed of dog.


Histiocytomas in dogs are generally benign and resolve on their own, but they can cause concern for pet owners when they first appear. Understanding these tumors and knowing when to seek veterinary advice are crucial steps in ensuring the health and well-being of your dog. If you ever notice an unfamiliar growth on your dog, it is always best to have it examined by a veterinarian to determine the appropriate course of action.


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