Insulinoma: When Seizures or Collapse Are Caused by Low Blood Sugar
A UK study of 278 dogs with insulinoma found seizures, weakness and collapse were the usual signs, and dogs that had surgery lived longer. What that means.
Written by thecanineledger
This page carries no advertising, and nothing on it is for sale.
If your dog has a seizure, collapses, or is suddenly weak, wobbly or trembling, call a vet now.
Our note: This advice is ours. We have no source for first aid during a low-sugar episode, so we give none. Ask your vet what to do.
An insulinoma is a tumour of the pancreas that releases too much insulin, which drives blood sugar too low. In 278 UK dogs diagnosed with one, the most common signs at diagnosis were seizures (37.8%), weakness (35.5%), collapse or fainting (31.5%) and muscle twitching (31.5%) (Kraai et al., Journal of Veterinary Internal Medicine 2026).
While those signs can point to many illnesses, the study’s main message is about what happened next. The authors conclude that “referral and surgical treatment are associated with improved clinical outcomes for dogs with insulinoma presenting to primary veterinary care.”
1. The study
The dogs. Researchers used VetCompass, a database of anonymised UK primary-care records. They found 278 dogs with insulinoma among 2,250,741 dogs under vet care in 2019.
Who got it. The median age at diagnosis was 10.4 years. The most common types were crossbreeds, West Highland White Terriers and Jack Russell Terriers.
Funding. The Kennel Club Charitable Trust and a pet insurer supported the work. The authors declare no conflicts of interest.
2. How it was diagnosed
Of the dogs with tests recorded in general practice, 92.7% had blood sugar and insulin measured together. About a third had an ultrasound scan of the belly, and a few had a CT scan.
Spread. Of 71 dogs scanned for spread, 57.7% showed none. Where it was suspected, the lymph nodes and liver were the most common sites.
Referral. About half the dogs (51.0%) were referred to a specialist or had specialist advice.
3. Treatment
| Approach | Share of dogs with treatment recorded |
|---|---|
| Medicines only | 163 of 271 |
| Surgery and medicines | 18.1% |
| Surgery only | 7.4% |
| Euthanised without treatment | 9.2% |
| Diet and rest only | 5.2% |
A figure that doesn’t add up. The paper gives the medicines-only group as 65.3%. 163 of 271 is 60.1%. We show the count.
4. How long dogs lived
Overall. The median survival from diagnosis was 291 days.
By treatment. Among dogs that died of insulinoma, the median survival was:
| Group | Median survival |
|---|---|
| Had surgery | 999 days |
| Medicines only | 311 days |
| No treatment | 147 days |
Referral. Referred dogs lived a median 673 days, against 275 for dogs not referred. After adjusting for other factors, dogs that had surgery had about half the risk of dying (hazard ratio 0.49).
Why caution is needed. Dogs chosen for surgery may have been younger or fitter to begin with. The authors found younger dogs lived longer: a median 930 days if diagnosed under 9, against 377 days at 9 or older.
Our note: The paper’s survival medians by treatment use only dogs whose death was related to insulinoma, which may bias the comparison.
→ First Seizure: What to Do, and What Counts as an Emergency
5. If your dog is diagnosed
- Ask about referral and whether surgery is an option.
- Ask whether the scan showed spread, and what that means for surgery.
- Ask what to do if your dog has an episode at home.
Our note: These points are ours, not the study’s.
6. What we could not verify
| Commonly said | What we found |
|---|---|
| “Insulinoma always causes seizures” | No. Seizures were recorded in 37.8% of dogs with signs noted. |
| “Surgery doubles survival” | Surgery was linked to longer survival, but healthier dogs may have been chosen for it. |
| “Insulinoma is a death sentence” | Survival varied widely. The median was 291 days overall, and longer with surgery. |
Sources
- Kraai K, et al. Clinical signs, management, and survival of 278 dogs diagnosed with insulinoma under primary veterinary care in the United Kingdom. J Vet Intern Med 2026: VetCompass study, 278 dogs, 2019. Supported by the Kennel Club Charitable Trust and a pet insurer
Always confirm with your vet before acting on anything on this page.