Clare Rushbridge BVMS.DipECVN. MRCVS
This article was prompted by the above enquiry and by the tragic death of "Candy" Bows. A recent paper found that having epilepsy was a risk factor for developing fatal acute pancreatitis (1)and I have had enough epileptic dogs develop this devastating disease for me to be concerned.
What is pancreatitis?
The pancreas is a gland that secretes digestive enzymes (substances that break down food e.g. fat in the intestine so that it can be absorbed). With pancreatitis (meaning inflammation of the pancreas), the digestive enzymes become activated and literally start digesting the pancreas. This results in release of toxic and inflammatory substances locally and into the bloodstream. Dogs with pancreatitis may be off their food and have abdominal pain with vomiting and/or diarrhoea. Severe cases (known as acute necrotising pancreatitis) develop severe dehydration, shock and can die.
What factors predispose to pancreatitis?
(i) Hyperlipidaemia or high blood fat is thought to precede and cause pancreatitis. Hyperlipidaemia may be caused by -
* High fat diet (>20% dry matter).
* Dietary indiscretion - i.e. eating something inappropriate, most commonly "human" food.
* Obesity
* Hypertriglyceridemia
i.e. high levels of fats called triglycerides in the blood. This occurs after eating a high fat meal and with obesity but can also occur because the dog is unable to metabolise fat properly. This is a familial problem in Miniature schnauzers, Briards and Shelties and occurs occasionally in other breeds. Hypertriglyceridemia is also a cause of epilepsy and dogs with seizures should be screened for this disease.
* Antiepileptic drugs? There is evidence to suggest that human lipid (i.e. fat) metabolism is altered by carbamazapine, phenytoin and phenobarbitone. Long-term phenobarbitone therapy in dogs has been associated with development of high blood cholesterol. In addition dogs on anti-epileptic drugs have increased appetite which makes them more likely to over-eat, scavenge and steal food i.e. increasing the risk of pancreatitis.
* Diseases affecting fat metabolism e.g. Cushing's syndrome (a disease where excessive corticosteroid is produced), diabetes mellitus,
hypothyroidism or kidney disease.
(ii) Drug induced
* Alcohol consumption is the most common cause of the disease in humans.
* Corticosteroids for example dogs receiving prednisolone for skin disease.
* Bromide? There is some evidence to suggest that phenobarbitone and bromide combination therapy increases the risk of pancreatitis. A recent paper published by the Canadian Veterinary Journal (2 )suggested that 10% of dogs receiving potassium bromide/phenobarbitone combination therapy had elevations of blood pancreatic enzymes and a clinical history suggestive of pancreatitis. Only 0.3% of the dogs receiving phenobarbitone alone had these changes. If these findings are correct then this is cause for concern, however in interpreting these authors' findings we have to take into account that the clinical signs of pancreatitis (i.e. anorexia, vomiting, diarrhoea, abdominal pain) occur in many other conditions and blood pancreatic enzyme levels are unreliable for diagnosing pancreatitis.
* Other anti-epileptic drugs Pancreatitis has been linked to valproic acid and carbamazepine therapy in humans.
(iii) Abdominal surgery
The pancreas is a very sensitive organ and can become inflamed if handled.
(iv) After shock
Pancreatitis has been known to occur after the blood supply to the pancreas is interrupted e.g. after bloat (gastric dilation and volvlus).
How is pancreatitis diagnosed?
Pancreatitis is a difficult disease to confidently diagnose because the most common clinical signs, vomiting and abdominal pain, occur in many other conditions most notably gastrointestinal disease. There may be a few non-specific changes in a routine blood test e.g. inflammation of the pancreas can cause blockage of the common bile duct resulting in an increase in blood bilirubin. Routine blood work should also be performed to rule out other causes of vomiting.
The most common laboratory test for the diagnosis of pancreatitis is measuring the blood levels of the digestive enzymes amylase and lipase. However this is not a very specific test as values can be increased in kidney disease, dehydration, and hyperlipidaemia. Furthermore some cases with pancreatitis have normal levels of these enzymes and the enzymes last for a short time so the test is only useful when the animal is displaying clinical signs.
Abdominal x-rays can reveal changes (e.g. haziness in the area of pancreas) however a normal x-ray does not rule out the possibility of pancreatitis.
Ultrasound examination of the pancreas is very useful, however, considerable operator experience is required to be able to find and
examine the pancreas properly.
How is pancreatitis treated?
The most important treatment is to correct dehydration, usually with intravenous fluids. Protein and fat, i.e. eating, stimulates the release of pancreatic enzymes and the mainstay of treatment is discontinuing oral fluid and food for 3 days (nil by mouth). Obviously this has implications for animals receiving oral medication. The phenobarbitone should be administered by injection but there is no injectable preparation of bromide.
If the vomiting ceases then food can then be gradually re-introduced but if 3 days of "nil by mouth" is ineffective then the patient will have to remain starved and be feed either directly into the intestine (with a tube) or into the vein.
Obese and hypertriglyceridaemic dogs recovering from pancreatitis should receive a low fat (<10% dry matter) and low protein (15-30% dry matter) diet. These are typically specially manufactured diets (e.g. Hills r/d (r)) or your veterinary surgeon may be able to give you a recipe for a homemade diet. Otherwise dogs can return to their normal diet (unless it was high in fat).
Advice for owners worried about the risk of pancreatitis
1) Avoid access to fatty food i.e. don't give fatty treats, choose a diet with a low fat content and make the dustbin dog proof.
2) Monitor your dog's weight. Most practices allow you to have your dog weighed free of charge. Seek advice for weight control from your vet or clinic nurse.
3) Any episodes of vomiting should be treated seriously - seek veterinary advice.
4) My current advice is that dogs receiving anti-epileptic drugs should have triglyceride levels periodically checked. This must be "at least a 12 hours starved" sample (otherwise levels will be high from the recent meal). A sample containing > 5 mmoles of triglycerides is abnormal. Hypertriglyceridaemia is managed by switching to a low fat (less than 12% dry matter basis) high fibre diet (your veterinary surgeon can advise you with regard to this) and add 2000mg of marine fish oil to the diet. It may also be advisable to have amylase and lipase routinely measured e.g. when drug concentrations or liver function are assessed however the usefulness of this has not been determined.
References
1. Hess RS et al Evaluation of risk factors for fatal acute pancreatitis in dogs. J Am Vet Med Assoc 1999; 214: 46-51.
2. Gaskill CL & Cribb AE Pancreatitis associated with potassium bromide/phenobarbitone combination therapy in epileptic dogs Can Vet J 2000; 41: 555-558.
EDITOR'S NOTE PANCREATITIS AND EPILEPSY
This article will be of understandable concern to our members - but please do not make any changes to your dog's medication without consulting your veterinarian. Remember that the majority of dogs (90%) will not be affected and that the benefits of combination therapy can far outweigh the risks discussed.
Clare is a consultant neurologist at the Stone Lion Veterinary Referral Centre, Wimbledon, London, England Tel: 0181 946 4228 and is very willing to take telephone enquiries from veterinary surgeons. Clare is also a European Specialist in Neurology