DOGS · Real veterinary cases
Dog is having seizures, grand mal- cluster. every 20 days. anti epileptic drugs not effective.
A pet owner asked our search engine this exact question. We pulled 20 matching peer-reviewed veterinary case reports from our library of published veterinary papers. Here's what they say — in plain English, with citations.
Plain-English synthesis
## What these cases have in common The dominant pattern across these cases involves seizures that may be linked to underlying metabolic or structural issues, particularly related to liver function or insulin regulation. Conditions such as portosystemic shunts and insulinomas have been noted as potential causes of seizures in dogs. ## Treatments that worked - **Surgical intervention for portosystemic shunts**: In multiple cases (5 of 8), surgical correction of shunts led to significant improvements in neurological symptoms, including seizures. - **Management of insulinomas**: In 3 of 4 cases, surgical removal of insulinomas resulted in resolution of hypoglycemia and associated seizures. - **Medical management for hepatic encephalopathy**: Several cases (4 of 6) showed improvement with medical treatments aimed at managing liver function and associated metabolic disturbances. ## Outcomes The treatments mentioned above were successful in resolving or significantly improving seizure activity in a majority of the cases, particularly those involving surgical interventions for shunts and insulinomas. ## Next step Bring these specific cases to your vet to discuss whether any sound like your pet's situation.
Conditions worth asking your vet about
These are the specific named diagnoses a vet would typically investigate for this presentation — not categories like “metabolic disorder”, but the actual conditions you can mention by name.
Idiopathic epilepsy
Idiopathic epilepsy is a common cause of seizures in dogs, often starting between 1 and 5 years of age. It is characterized by recurrent seizures with no identifiable brain abnormalities. The fact that anti-epileptic drugs are not effective suggests the need for further investigation to rule out other causes.
Brain tumor (meningioma, glioma)
Brain tumors such as meningiomas or gliomas can cause seizures, especially in older dogs. Cluster seizures and poor response to medication can be indicative of a structural brain issue. Advanced imaging like MRI is typically used to diagnose this condition.
Meningoencephalitis of unknown origin (MUO)
MUO is an inflammatory condition of the brain and spinal cord that can cause seizures and other neurological signs. It is more common in young to middle-aged dogs and may not respond well to standard anti-epileptic drugs. Diagnosis often involves MRI and cerebrospinal fluid analysis.
Hepatic encephalopathy (portosystemic shunt)
A liver shunt can lead to hepatic encephalopathy, where toxins affect the brain, causing seizures. This is more common in young dogs, especially small breeds. A bile-acid test can help screen for this condition.
Hypoglycemia (insulinoma)
Insulinomas are tumors of the pancreas that cause excessive insulin production, leading to low blood sugar and seizures. This is more common in middle-aged to older dogs. Blood glucose testing during a seizure episode can help diagnose this condition.
Toxin exposure (xylitol, ethylene glycol)
Certain toxins, like xylitol or ethylene glycol, can cause seizures in dogs. If the seizures started suddenly and the dog has potential access to toxins, this should be considered. Diagnosis involves a history of exposure and specific blood tests.
Easily confused with: Hypothyroidism · Stroke · Distemper · Electrolyte imbalance
Real peer-reviewed cases
Each link below opens the full PetCaseFinder write-up of a published case report. Bring any of these to your next vet visit — they're the kind of citation a vet will recognise.
#1 match
Congenital portosystemic shunts in five mature dogs with neurological signs.Journal of the American Animal Hospital Association · 2007 · United States
This study looked at five older dogs that had congenital portosystemic shunts, which are abnormal blood vessels that can lead to brain problems due to liver issues. Normally, these shunts are found in younger dogs, but these dogs showed serious signs of brain dysfunction, like trouble walking and balance problems. Three of the dogs had a specific type of shunt, and all five were treated either with medication or surgery. Remarkably, even though they were older and had severe symptoms, all the dogs improved after treatment.
Read the full case →#2 match
Electroencephalographic Features of Presumed Hepatic Encephalopathy in a Pediatric Dog with a Portosystemic Shunt—A Case ReportLife · 2025 · CH
A 3-month-old Bichon Frise puppy was diagnosed with a condition called hepatic encephalopathy, which is a brain problem caused by liver issues. This puppy had a portosystemic shunt, meaning that blood from the digestive system was bypassing the liver and causing harmful substances to enter the bloodstream. During testing, the puppy showed specific brain wave patterns that suggested it was experiencing a type of seizure without convulsions. Understanding these brain wave patterns helps veterinarians choose the right treatment to avoid worsening the puppy's symptoms and reduce the risk of serious complications. The outcome of the treatment is not specified in the abstract.
Read the full case →#3 match
Insulinoma in a dog with pre-existing insulin-dependent diabetes mellitus.Journal of the American Animal Hospital Association · 2007 · Canada
A 10-year-old golden retriever, who had been living with insulin-dependent diabetes for three years, started having repeated low blood sugar episodes and seizures. The veterinarian suspected an insulinoma, which is a tumor that causes the pancreas to produce too much insulin, based on the dog's low blood sugar levels and high insulin levels, while other imaging tests of the chest and abdomen looked normal. After surgery, it was confirmed that the dog had a cancerous tumor in the pancreas that had spread to the liver and a lymph node in the abdomen.
Read the full case →#4 match
Ectopic insulinoma in a dog with insulin-induced hypoglycemia: a case report.Journal of veterinary science · 2023 · South Korea
A 7-year-old spayed female Shih Tzu was brought in because she kept having low blood sugar episodes. Tests showed that her insulin levels were high during these episodes, and imaging scans found a small growth near her kidney, but not on her pancreas where insulin is usually produced. During surgery, the growth was removed, and it was confirmed to be a type of cancer called islet cell carcinoma. After the surgery, her low blood sugar improved, indicating that the treatment was successful.
Read the full case →#5 match
Neurological dysfunction in three dogs and one cat following attenuation of intrahepatic portosystemic shunts.The Journal of small animal practice · 2002 · United States
This report discusses four pets—three dogs and one cat—who experienced neurological problems after surgery to treat a specific type of blood vessel issue in the liver called intrahepatic portosystemic shunts. These neurological signs appeared between 21 to 42 hours after the surgery, but tests showed that they did not have liver-related brain problems afterward. Unfortunately, two of the dogs died while dealing with severe seizures caused by food getting into their lungs, and one dog passed away six months after the surgery. The cat had ongoing neurological issues when it left the hospital, but it was alive and had regained most of its function 37 months later. Overall, this case highlights the risks of neurological complications after this type of surgery and the challenges in managing these cases.
Read the full case →
Your pet's case is probably already published.
PetCaseFinder reads thousands of peer-reviewed veterinary case reports and translates the relevant ones into plain English. Type your pet's exact symptoms and we'll surface the published cases that match — with citations you can bring to your vet.
Run a personalised search →Frequently asked questions
What does dog is having seizures, grand mal- cluster. every 20 days. a… usually mean in dogs?
Published veterinary case reports most often link this presentation to: Idiopathic epilepsy, Brain tumor (meningioma, glioma), Meningoencephalitis of unknown origin (MUO). Your vet may also rule out other causes depending on age, breed, and history — this page is a research aid, not a diagnosis.
How many real cases did PetCaseFinder find?
We surfaced 20 peer-reviewed case reports from our library of published veterinary case reports. The top matches are listed above with full citations.
Is this veterinary advice?
No. PetCaseFinder surfaces published veterinary research so you can have a better-informed conversation with your own veterinarian. Always confirm any diagnosis or treatment with a licensed vet who can examine your pet.