At what age are dogs developing cancer?

Canine cancer is a leading cause of death in dogs, but until recently, there haven’t been extensive studies to understand at what age dogs are getting diagnosed with cancer and which breeds are at elevated risk. Such information is important and can help families determine when to begin screening their dogs for cancer.

In a published paper, data from 3452 dogs were drawn from three large cohorts across multiple veterinary clinics in the United States.  The age of cancer diagnosis was analyzed based on breed type, gender, neuter status, and weight.

The first cohort included 663 dogs enrolled in the CANcer Detection in Dogs (CANDiD) study from 2019 to 2021, with all participants receiving comprehensive cancer staging through various veterinary institutions. The second cohort, with 1,888 dogs, came from the National Cancer Institute’s Biological Testing Tumor Repository, which gathered samples from major U.S. academic institutions like Colorado State University and the University of California-Davis. The third cohort included 901 dogs treated at the University of California-Davis Veterinary Medical Teaching Hospital over a 15-year period. 

Here are the results of the study:

1. At what age are dogs getting cancer?

   
   

   Based on the results, the median age of diagnosis is 8.8 years.  Here’s the distribution by age.  

   

   Distribution of 3,452 client-owned dogs by age at cancer diagnosis.

2. Purebred dogs are diagnosed earlier than mixed-breed dogs.

   
   

   For the 2,537 purebred dogs, represented by 122 distinct breeds, the median age of diagnosis was 8.0 years old.

   
   

   For the 915 mixed-breed in this study, the median age group at diagnosis is 9.5 years.  

   
   

   

   Age distribution at cancer diagnosis for mixed-breed or other vs. purebred dogs

3. Larger dogs are diagnosed earlier with cancer

   
   

   In this study, dogs’ weight ranged from 2.5-98 kg. The median age at cancer diagnosis was younger for larger dogs. 

   
   

   For example, dogs with weights ranging from 2.5-5 kg had a median age at cancer diagnosis of 11 years. On the other hand, dogs with weights greater than or equal to 75 kg had a median age of 5 years. 

   
   

   

   Median age at cancer diagnosis by weight for 2,551 dogs that had a documented weight.

4. Which breeds are getting diagnosed with cancer at what age?

   
   

   For the 2,537 purebred dogs, represented by 122 distinct breeds, the median age of diagnosis was 8.0 years. 

   
   

   The breeds that were diagnosed at the youngest median ages were: 

   • Mastiffs: 5 years

   • Saint Bernards, Great Danes, Bulldogs: 6 years

   • Irish Wolfhounds: 6.1 years

   • Boxers: 6.2 years

   • Vizslas and Bernese Mountain Dogs: 7 years

   
   

   

   Age distribution at cancer diagnosis by breed for breeds represented by more than or equal to 10 dogs.

This figure shows the age distribution at cancer diagnosis for different dog breeds, using boxplots. The shaded boxes represent the interquartile range (IQR), which includes the middle 50% of diagnosis ages, while the line inside each box shows the median age at diagnosis. The whiskers extend to the smallest and largest values within 1.5 times the IQR, and any dots beyond the whiskers are outliers, indicating ages at diagnosis that are unusually early or late.

5. Dependence on gender and neuter status

   
   

   Results showed that the median age of cancer diagnosis for males was 8.4 years, while the median age for females was 9 years. This implies that the age of cancer diagnosis in males was significantly lower or younger than in females. 

   
   

   The median age of cancer diagnosis for intact males (7.9 years) was also lower compared to castrated males (8.9 years), which was also shown in intact females (7.3 years) and spayed females (9.0 years). In short, intact dogs had a lower or younger median age at diagnosis compared to neutered dogs. 

Comparison Groups	Median Age at Cancer Diagnosis
Male: Female (1,900:1,552)	8.4 : 9.0
Castrated Male: Spayed Female (1,452:1,390)	8.9 : 9.0
Intact Male: Intact Female (446:161)	7.9 : 7.3
Castrated Male: Intact Male (1,452:446)	8.9 : 7.9
Spayed Female: Intact Female (1,390:161)	9.0 : 7.3

 Age at cancer diagnosis by sex and neuter status of the study population.

The study recommended that dogs undergo annual cancer screening two years before the median age of cancer diagnosis according to their breed or weight. This implies that cancer screening for all dogs should start at the age of 7, while breeds with a lower median age at cancer diagnosis should start at the age of 4.

Here’s additional summary from the study. 

ACCORDING TO	MEDIAN AGE
Age Groups	8.8 years
Breed (Purebred)	8.0 years
Breed (Mixed-breed)	9.5 years
Weight (2.5-5 kg)	11 years
Weight (more than or equal to 75 kg)	5 years
Sex (Male)	8.4 years
Sex (Female)	9 years
Intact Males	7.9 years
Castrated Males	8.9 years
Intact Females	7.3 years
Spayed Females	9.0 years
Lymphoma or lymphoid leukemia, mast cell tumor, and histiocytic sarcoma	Less than 8 years
Malignant melanoma and cancers of the mammary gland, lung, and urinary bladder	Greater than or equal to 11 years

---

Check out other articles and videos

• Curing Hemangiosarcoma: New Calviri Vaccine Study for Canine Patients

• New Hope for Cures: Immune Checkpoint Inhibitors (including Gilvetmab)

• New Canine Cancer Screening Tests

Questions? Email us at info@ccralliance, and we'll get back to you as soon as we can!

Canine Cancer Alliance is a non-profit organization supporting research for canine cancer cures.

DONATE

All information on the Canine Cancer Alliance website is for educational purposes only. It is not intended to be a substitute for professional veterinary advice.

Always seek guidance from your veterinarian with any questions regarding your pet’s health and medical condition.