Evidence-Based Treatment Guide
45 evidence-graded diagnoses with treatment protocols for dogs.
45 of 45 diagnoses
WHO Stage III-V
Most common haematopoietic neoplasm in dogs, representing ~24% of all canine neoplasms. Estimated incidence 20-107 per 100,000 dogs per year. B-cell phenotype accounts for 60-80% of cases.
WHO Stage III-V
Virtually all dogs with multicentric lymphoma will relapse after first-line therapy. Median first remission duration with CHOP is 6-11 months. Second remissions are typically shorter than first.
WHO Stage III-V
Accounts for 15-30% of canine multicentric lymphoma cases. Carries a significantly worse prognosis than B-cell lymphoma. More frequently associated with hypercalcaemia and mediastinal involvement.
Uncommon form of lymphoma. Epitheliotropic form (mycosis fungoides-like) is T-cell in origin and more common. Non-epitheliotropic form has better prognosis. Can mimic dermatologic conditions, causing diagnostic delay. NOTE: No dedicated clinical trials for canine cutaneous lymphoma were identified as of March 2026. This represents a genuinely underserved area of veterinary oncology research. The ORBIT trial (University of Minnesota) accepts aggressive lymphoma broadly but is not cutaneous-specific.
Most common skin tumour in dogs, accounting for ~17.8% of all canine cutaneous neoplasms. Kiupel low-grade represents approximately 85% of Patnaik Grade II tumours.
High-grade MCT represents approximately 14.4% of Patnaik Grade II tumours and all Patnaik Grade III. Shar-Peis are at extremely high risk (OR 26-28) and present younger. Weimaraners also high risk.
localised
Uncommon but breed-associated. Bernese Mountain Dogs have ~25% lifetime prevalence. Arises from dendritic cells. Periarticular location is classic in Bernese Mountain Dogs.
disseminated
Disseminated form carries extremely poor prognosis. Same breed predispositions as localised but often presents at advanced stage.
Benign-behaving round cell tumour of the skin. Excellent prognosis with surgical excision. Distinct from extramedullary plasmacytoma (which has more variable behaviour) and multiple myeloma.
Sexually transmitted canine tumour with unique biology — naturally transplantable allogeneic cancer. Endemic globally in at least 90 countries but rare in the US, Canada, and Northern Europe. Common in regions with free-roaming dog populations. In the US, primarily seen in imported dogs or dogs from border regions.
Stage I (confined to spleen) – Stage II (ruptured with regional involvement)
Accounts for 5–7% of all canine tumours; 25–100× higher incidence in dogs than humans. Most common splenic malignancy. Often presents as emergency haemoabdomen.
Stage III (distant metastasis present at diagnosis)
A significant proportion of dogs with splenic HSA present with Stage III disease. Metastases most commonly to liver, omentum, lungs, and peritoneum.
Second most common site for HSA after spleen. Right atrium/auricular appendage is typical location. Often presents with pericardial effusion and cardiac tamponade. May occur concurrently with splenic HSA.
Dermal HSA (actinic / solar-induced) occurs in lightly pigmented, short-haired dogs on ventral abdomen and prepuce. Biologically less aggressive than visceral HSA. Subcutaneous HSA has intermediate behaviour — worse than dermal, better than splenic.
Stage I (localised) – III (metastatic)
Most common primary bone tumour in dogs (~85% of skeletal tumours). Incidence 27× higher than in humans. ~90–95% of dogs have micrometastatic disease at diagnosis. Large and giant breeds overwhelmingly predisposed.
~15% of canine osteosarcoma. Less aggressive metastatic behaviour than appendicular OSA in some sites. Prognosis varies significantly by anatomical site — mandibular best, vertebral worst.
STS represents a heterogeneous group of mesenchymal tumours with similar biological behaviour. Grade I–II tumours are locally invasive but metastatic potential is low (Grade I ~7% recurrence, Grade II ~34% recurrence after marginal excision).
Grade III STS represents ~10% of all STS. Local recurrence rate 75% after marginal excision. Metastatic rate significantly higher than lower grades.
Second most common primary bone tumour in dogs. Prognosis significantly better than osteosarcoma overall. Behaviour and prognosis depend heavily on tumour grade and anatomical site.
Uncommon tumour arising from skull and flat bones. Locally aggressive with significant metastatic potential (56%). Slow-growing but progressive.
Uncommon tumour arising from periarticular tissues. Locally aggressive with metastatic potential, particularly in high-grade tumours. Often presents as progressive lameness with periarticular swelling.
Third most common oral malignancy in dogs. Critical diagnostic trap: oral fibrosarcoma in large breeds (especially Golden Retrievers, 54% of cases) appears histologically low-grade but behaves aggressively (high local recurrence, metastatic potential). Predominantly maxillary location (72%).
T1-T3, N0/N1
Most common urinary tract tumour in dogs. Accounts for ~2% of all canine malignancies. Trigone location in >90% of cases, often involving ureteral orifices.
Modified Owen TNM Stages I-V
Most common tumour in intact female dogs. ~50% malignant. Risk dramatically reduced by early OHE (0.5% risk if spayed before first oestrus, 8% after first, 26% after second). Caudal glands (4th and 5th) most commonly affected.
Accounts for ~2% of cutaneous/subcutaneous tumours and ~17% of perianal tumours. Paraneoplastic hypercalcaemia in 25-50% at diagnosis. High metastatic rate to sublumbar lymph nodes (50-80% at diagnosis).
Modified Adams staging (I-IV)
~1-2% of all canine tumours. Most common nasal tumour type. Adenocarcinoma most frequent histotype. Locally invasive; distant metastasis late in disease. Dolichocephalic and mesocephalic breeds overrepresented.
WHO TNM staging
Second most common oral tumour after melanoma. Biological behaviour varies dramatically by location: rostral/gingival SCC has low metastatic rate and good surgical prognosis; tonsillar SCC is highly metastatic with poor prognosis.
Two distinct presentations: UV-induced cutaneous SCC (ventral abdomen, light-skinned breeds) and subungual/digital SCC (dark-coated large breeds). Digital SCC is the most common digital tumour in dogs. Metastatic rate varies: cutaneous ~20%, digital ~15-30% (higher for multiple digit involvement).
Most common primary hepatic tumour in dogs. Three morphological forms: massive (single large mass — ~55%, best prognosis), nodular (multiple nodules — ~30%), diffuse (~15%, worst prognosis). Many are incidental findings on abdominal imaging.
Mobile vs Fixed/Invasive
~1-4% of all canine tumours. ~90% of thyroid tumours in dogs are malignant (unlike cats where ~90% are benign). Most are non-functional (euthyroid). Mobile tumours have much better surgical prognosis than fixed/invasive.
Based on tumour number, size, LN status
~1% of all canine tumours. Often incidental finding on thoracic imaging. Adenocarcinoma is the most common histotype. Solitary masses have better prognosis than multiple nodules.
Uncommon but highly aggressive. Occurs in BOTH castrated and intact male dogs (unlike benign prostatic hyperplasia which is only intact). Some evidence that neutered dogs may be at equal or higher risk. Typically presents with dysuria, haematuria, or hindlimb stiffness from sublumbar LN or skeletal metastasis.
Uncommon (~1% of canine tumours). Renal cell carcinoma is the most common primary renal malignancy. Often unilateral. May be incidental finding on imaging. German Shepherds at hereditary risk (BHD gene mutation — renal cystadenocarcinoma).
Uncommon. Most common malignant tumour of the canine ear canal. Chronic otitis externa may be a predisposing factor. Often diagnosed late due to location within ear canal.
Hepatoid gland tumours are common in intact male dogs but ~90% are benign adenomas. Adenocarcinomas (malignant) are less common. Distinguished from anal sac apocrine gland adenocarcinoma — different tumour type. Testosterone-responsive (adenomas regress with castration; carcinomas do not).
WHO Stage I-IV
Most common malignant oral tumour in dogs. Represents ~30-40% of oral malignancies. Highly aggressive with early metastasis to regional lymph nodes and lungs.
Common skin tumour. Majority (>80%) of cutaneous melanocytic tumours of the haired skin are benign melanocytomas. Malignant cutaneous melanomas of haired skin tend to behave less aggressively than oral melanomas, but a subset will metastasise.
All nail bed melanomas should be considered biologically malignant regardless of histological features. Black-coated breeds may be predisposed. Metastatic rate is intermediate between cutaneous and oral melanoma.
Most common primary intraocular neoplasm in dogs. 94% affect iris/ciliary body, 6% choroid. Approximately 82% are benign melanocytomas with low metastatic rate (~3.3%). Distinct biology from oral and digital melanoma.
Stage I (pancreas only) to Stage III (metastatic)
Uncommon but clinically significant tumour. Presents with paraneoplastic hypoglycaemia (weakness, collapse, seizures). Most are malignant with metastatic potential to liver and regional lymph nodes.
Uncommon tumour arising from adrenal medulla chromaffin cells. Can be functional (catecholamine-secreting) causing episodic hypertension, tachycardia, panting. Often incidental finding on abdominal imaging. Can be locally invasive (vena cava invasion).
Most common primary intracranial tumour in dogs. Typically extra-axial, potentially resectable depending on location. Some studies suggest dolichocephalic breeds may be predisposed, though this association is less firmly established than the brachycephalic predisposition for gliomas. Often discovered when neurological signs develop (seizures, behavioural changes, circling).
Second most common primary intracranial tumour in dogs after meningioma. Intra-axial (within brain parenchyma), making complete surgical resection generally not possible. Brachycephalic breeds are strongly predisposed. Presents with seizures, behavioural changes, neurological deficits.
Pituitary tumours are the most common cause of pituitary-dependent hyperadrenocorticism (Cushing's disease) in dogs. Macroadenomas (>10mm) can cause neurological signs by compression of surrounding brain tissue. Most are functional (ACTH-secreting).
Uncommon tumour of chemoreceptor tissue at the heart base. Slow-growing but can cause pericardial effusion and tamponade. Brachycephalic breeds are predisposed (chronic hypoxia theory). Low-moderate metastatic rate (~13%).