Mast Cell Tumours in Cats: Causes, Symptoms & Treatment

Mast cell tumours (MCTs) are uncommon yet significant cancers in cats. They originate from mast cells, a type of white blood cell involved in allergic and inflammatory responses. 

Although dogs are more frequently affected by mast cell tumours, feline MCTs still require prompt attention, as timely diagnosis and treatment can significantly improve a cat’s quality of life and overall prognosis. In this article, we will explore the causes, symptoms, diagnosis, and treatment options for mast cell tumours in cats.

What Are Mast Cell Tumours in Cats?

Mast cells are immune cells responsible for storing and releasing inflammatory substances like histamine and heparin. These substances help fight infections and repair tissues, but when mast cells multiply uncontrollably, they form a mast cell tumour.

In cats, MCTs commonly present in two main forms:

1. Cutaneous (Skin) MCTs

   • Appear on or just beneath the skin’s surface.

   • Often present as solitary nodules, most frequently on the head and neck.

   • Usually slow-growing, with many remaining benign or low-grade.

   • May present as clusters of tumours together or spread over the body.

     
     

2. Visceral (Splenic/Abdominal) MCTs

   • Found in organs such as the spleen, liver, or intestines.

   • More invasive and challenging to detect early, as visible lumps are less likely.

Understanding the specific type and location of your cat’s mast cell tumour is key to determining the most appropriate treatment plan.

Causes & Risk Factors

Although the exact cause of mast cell tumours in cats remains unclear, several factors may increase the risk:

1. Breed Predisposition

   • Certain purebred cats, such as the Siamese, appear more prone to developing MCTs—particularly the cutaneous form.

     
     

2. Age

   • MCTs can occur at any age but are more often diagnosed in middle-aged to older cats.

     
     

3. Genetic & Environmental Factors

   • A potential combination of genetic susceptibility and unknown environmental triggers may influence tumour development.

Because many of these factors are difficult or impossible to modify (e.g., breed, genetics), early detection is usually the most practical strategy for improving outcomes.

Common Symptoms

The symptoms of mast cell tumours in cats can be subtle or varied, depending on whether the tumour is cutaneous or visceral:

1. Skin Lumps or Nodules

   • Small, firm bumps on the head, neck, or trunk.

   • Might appear slightly raised and can sometimes be itchy or inflamed.

     
     

2. Gastrointestinal Issues (More Common with Visceral MCTs)

   • Vomiting, diarrhoea or constipation, and reduced appetite if the spleen, liver, or digestive tract is involved.

   • Weight loss or general malaise over time.

     
     

3. Enlarged Abdomen or Palpable Mass

   • In advanced visceral mast cell tumours, an enlarged spleen may cause abdominal distension.

   • Cats might become lethargic or show discomfort when the abdomen is touched.

     
     

4. Skin Ulceration or Sores

   • Tumours may ulcerate, bleed, or develop scabs on the surface.

   • Excessive grooming or scratching could lead to secondary infections.

If you observe persistent lumps, unexplained weight loss, or changes in your cat’s behaviour, consult your veterinarian for a thorough examination.

Diagnosis

A prompt and accurate diagnosis is essential for managing mast cell tumours effectively. Your veterinarian may recommend:

1. Physical Examination

   • Inspection and palpation of any suspicious lumps.

   • Assessment of overall body condition and lymph node enlargement.

     
     

2. Fine Needle Aspiration (FNA)

   • A minimally invasive procedure using a thin needle to collect cell samples from the suspected tumour.

   • Microscopic analysis can often confirm the presence of mast cells.

     
     

3. Biopsy & Histopathology

   • For larger or ambiguous masses, a surgical biopsy may be performed to obtain a more extensive tissue sample.

   • Lab analysis helps determine tumour type, aggressiveness, and grade.

     
     

4. Imaging Studies

   • X-rays or ultrasound to check for internal tumours (especially in the spleen or liver).

   • Blood tests might be conducted to evaluate overall organ function and rule out other conditions.

Treatment Options

The treatment approach largely depends on the location and grade of the mast cell tumour, as well as your cat’s overall health:

1. Surgical Removal

   • For cutaneous MCTs, surgery is often the first line of treatment.

   • A wide surgical margin is typically aimed for, ensuring no residual tumour cells remain.

   • In cases of splenic MCTs, a splenectomy (spleen removal) may be advised.

     
     

2. Chemotherapy

   • May be recommended if the tumour is high-grade, widespread, or non-operable.

   • Can help reduce tumour size, manage secondary spread, and improve quality of life.

     
     

3. Corticosteroids & Supportive Medications

   • Steroids (e.g., prednisolone) can help diminish tumour growth and relieve inflammation.

   • Antihistamines (e.g., famotidine, ranitidine) may manage excessive histamine release, preventing gastric ulcers or other complications.

     
     

4. Radiation Therapy

   • Less commonly used in cats compared to dogs, but can be an option for incompletely excised cutaneous tumours or those in difficult locations.

   • Typically delivered over multiple sessions to minimise side effects.

     
     

5. Palliative & Supportive Care

   • Even if the tumour is advanced, supportive treatments—such as pain relief, nutritional support, and fluid therapy—can enhance comfort and overall quality of life.

Prognosis & Life Expectancy

The prognosis for mast cell tumours in cats varies, influenced by:

• Tumour Type & Grade

  • Many cutaneous MCTs in cats are low-grade, meaning slow progression and a favourable prognosis after surgical removal.

  • Visceral MCTs, particularly involving the spleen or multiple organs, can be more challenging to treat, though surgical intervention (e.g., splenectomy) may still yield significant benefits.

• Overall Health

  • Cats with pre-existing conditions or compromised immune systems may recover more slowly or experience more complications.

• Early Detection

  • Identifying mast cell tumours when they are still small often means more treatment options and a better outcome.

Your veterinarian or a veterinary oncologist can offer more detailed, individualised insights based on your cat’s specific diagnosis.

Prevention & Early Detection

Although it’s not always possible to prevent mast cell tumours—especially given genetic factors—there are practical measures owners can take:

1. Regular Check-Ups:

   • Schedule routine veterinary appointments, especially for older cats.

   • Professional exams can detect suspicious lumps at an early stage.

2. Home Monitoring:

   • Gently feel your cat’s body for unusual bumps or growths during grooming sessions.

   • Keep note of any changes in size, shape, or behaviour over time.

3. Prompt Veterinary Attention:

   • Swiftly address any lumps, skin lesions, or unexplained weight loss.

   • Rapid diagnosis and treatment can mean the difference between a simple procedure and a more complex intervention.

Final Thoughts

Mast cell tumours in cats, while less common than in dogs, still pose a notable risk—particularly if left undetected. Early identification and proper diagnostic work are crucial, enabling veterinarians to devise a targeted treatment plan, whether that involves surgery, chemotherapy, or other supportive measures.

With timely veterinary care, many cats with mast cell tumours can maintain good quality of life and, in many cases, achieve long-term control of the condition. If you observe any unusual lumps, bumps, or health changes in your cat, don’t hesitate to contact your vet for an evaluation.