Disease Guide

Tumours in Dogs & Cats: Symptoms, Diagnosis & Care Guide [2025]

Aquatic mold infection — difficult to treat with a poor prognosis

Last updated: 2026/01/06
Pethealthmap Editorial Team
Sources: AVMA, ACVIM, National Taiwan University Veterinary Teaching Hospital

When to See a Vet

Seek Emergency Care Immediately

  • Severe vomiting with inability to keep fluids down or signs of dehydration
  • Continuous large-volume vomiting of blood or significant fresh red blood in stools
  • Sudden collapse, unresponsiveness, or rapid/labored breathing

Schedule a Clinic Visit Soon (Within 24–72 Hours)

  • Repeated vomiting but still able to eat small amounts or noticeably lower energy
  • Ongoing weight loss or significant thinning over a short period
  • Progressive abdominal distension or a palpable lump becoming more prominent

01What symptoms indicate something is wrong?

Tumours and systemic diseases in dogs and cats often present with non-specific symptoms — including gastrointestinal signs, unexplained weight loss, or localised masses — and may be subtle in early stages.

  • Recurrent or persistent vomiting that requires evaluation for an underlying systemic condition
  • Persistent diarrhoea or bloody stools, which may indicate intestinal involvement and warrant investigation
  • Noticeable weight loss or unexplained wasting that needs identification and monitoring
  • A localised lump, subcutaneous mass, or abdominal distension that should be assessed for its source
  • Persistent pain or abdominal discomfort (especially noticeable during movement) — veterinary assessment recommended

Seek emergency care immediately if you notice the following symptoms:

  • ⚠️ Profuse vomiting with inability to keep fluids down or signs of dehydration
  • ⚠️ Continuous vomiting of large amounts of blood or passing large amounts of fresh red blood in stools
  • ⚠️ Sudden collapse, unresponsiveness, or rapid laboured breathing

02How to assess abnormalities at home: key observations and when to seek emergency care

Observing and recording specific details before your vet visit can help guide the priority of examination and treatment.

  • Note the frequency, timing, and contents of vomiting (whether it contains blood or food remnants)
  • Observe, photograph, or video bowel movements, noting frequency and any changes in consistency
  • Weigh your pet weekly and record the values and dates of any changes
  • Record changes in alertness, interaction, and activity level (such as increased lethargy or reduced play)
  • Track trends in appetite, food intake, and water consumption
  • Collect and bring a sample of vomit or faeces (if available) to the clinic for testing

03How does the vet make a diagnosis? Common examination and test procedures

At the clinic, the vet will combine physical examination with laboratory, imaging, and pathology tests to confirm the diagnosis and staging.

Physical examination

palpation of the abdomen, assessment of skin masses, and lymph node size

X-ray

initial evaluation of thoracic and abdominal organs, calcification, or mass contours

Ultrasound

assessment of abdominal organs, tumour location, and guidance for aspirates or biopsies

Tissue biopsy or fine-needle aspiration (FNA)

examination of cell morphology to aid diagnosis

Blood and biochemistry panel

evaluation of organ function and detection of infection or anaemia

Advanced imaging (CT/MRI)

used to define tumour extent and assist with surgical planning

Bacterial culture or PCR

performed if infection or a specific pathogen is suspected

04Post-diagnosis treatment and care: medication, dietary adjustments, and home management

Treatment depends on the tumour type and extent; combining targeted therapy with supportive care and regular monitoring can improve prognosis and quality of life.

  • Follow your vet's instructions for medication or supportive therapy, and attend scheduled rechecks to assess response
  • Surgical excision requires pre-operative imaging and bloodwork; follow up regularly after surgery to monitor the wound and imaging results
  • Chemotherapy or radiotherapy is assessed and arranged by a specialist centre, with periodic follow-up visits
  • Dietary adjustment and nutritional support, with a palatable meal plan designed for reduced appetite
  • Regular bloodwork and imaging to monitor disease progression and treatment side effects
  • Home care includes pain management, comfort care, and guidance on activity restrictions

05What to prepare before the vet visit: key information to help your vet diagnose quickly

1
A written record of when symptoms first appeared and how they have changed day by day
2
Recent weight measurements, plus photos or videos of symptoms (vomiting episodes, visible masses)
3
A list of all current medications and supplements, including names and dosing frequency
4
Details of the food brand, portion size per meal, and any recent changes in feeding habits
5
If available, preserve and bring a vomit or faecal sample to the clinic
6
Call ahead to confirm and book a clinic with on-site imaging and pathology capabilities

This content is for reference only and cannot replace a professional veterinary diagnosis. If your pet shows signs of illness, please seek veterinary care promptly.

Frequently Asked Questions (FAQ)