Canine pancreatitis causes

Pancreatitis is common in canine medicine^1,2. Its overall prevalence has been estimated as 0.8% in dogs, being higher in some specific breeds². However, diagnosis of pancreatitis can be very challenging – especially if we want to conclude pancreatitis as a cause of the clinical signs. 

Diagnosis becomes even more difficult for chronic cases. Histopathologic evidence of pancreatitis in up to 65% has been detected during postmortem², even in dogs that died from unrelated causes, and the consequences of failing to diagnose these cases are unknown.

Equally, inflammation of the pancreas (pancreatitis) may exist, but this is not the cause of the problems. Finally, these difficulties in diagnosing pancreatitis also make it difficult to obtain definitive conclusions in the research field.

Causes of pancreatitis

From a pathophysiologic point of view, in a basic way, the cause of acute pancreatitis is due to activation of inert zymogens (precursors of digestive enzymes) within pancreatic acinar cells rather than within the duodenal lumen. If this occurs at a low level, the pancreas has safety mechanisms to control it, but once these mechanisms are overwhelmed, further inflammation occurs and a vicious cycle begins, leading to more severe and generalised inflammation.

Chronic pancreatitis is hypothesised to be a consequence of an “acute event” or chronic immune-mediated inflammation in English cocker spaniels¹.

Overall, a definitive, more clinically useful cause for pancreatitis has not been proven and it is usually considered idiopathic, but several risks factors have been considered. In many instances an inciting cause is not found, but in dogs the following factors have been associated with pancreatitis (acute and/or chronic)^1-3:

• Diet:
  • High-fat, low-protein diets have been implicated in the development of pancreatitis in dogs and rodent models, but not proven in a definitive manner.
  • Alimentary indiscretion, including access to trash and table scraps, has been considered a risk factor.
• Hypertriglyceridaemia in miniature schnauzers and it may be the case in other breeds¹.
• Obesity. A study in overweight and obese dogs showed an association of hypertriglyceridaemia with markedly increased canine pancreatic lipase immunoreactivity concentration, but not with development of clinical pancreatitis¹.
• Endocrinopathies. Hyperadrenocorticism, hypothyroidism and diabetes mellitus have been linked to pancreatitis.
• Infectious diseases. leishmaniasis, babesiosis.
• Drugs:
  • Anti-epileptics: potassium bromide, phenobarbitone.
  • Immunosuppressants/chemotherapy: azathioprine, L-asparaginase.

For most of these drugs an idiosyncratic reaction is considered as the mechanism and it does not seem to be dose-dependent, making it difficult to predict the risk in advance.

• Previous surgeries. Previous surgeries other than neutering were associated with increased occurrence of pancreatitis in a canine study¹. In human medicine, patients undergoing surgery of organs distant from the pancreas have also been shown to be at increased risk of pancreatitis, suggesting that hypoperfusion of the pancreas during anaesthesia may be another concern.
• Intoxications. Zinc, organophosphates.
• Snakebites. Can be of importance in some areas.
• Trauma. For example, road traffic collision.
• Genetic. In miniature schnauzers, some mutations have been identified in affected dogs, but the role of them remains controversial¹.
• As a part of a more generalised inflammatory process.

Signalment

Several breeds have been reported to be at increased risk, such as miniature schnauzers, Yorkshire terriers, cocker spaniels and cavalier King Charles spaniels, among others¹.

Being neutered (male/female) or male has been reported in a study as a risk factor¹. Although dogs of any age can develop pancreatitis, it is more common in middle-aged or older dogs².

What can we do?

Many of the aforementioned points are intrinsic factors of the patient/concomitant medical conditions or unexpected events, for which we cannot do much. Obviously, specific treatment of some conditions (endocrinopathies, infectious diseases, hypertriglyceridaemia) should be implemented and this may decrease the risk of pancreatitis.

“Where” vets and owners can play a role in the prevention of an episode of pancreatitis (or relapse/persistence of signs) is by managing diet/bodyweight and of medications.

• Diet/bodyweight:
• Maintain the dog in a good body condition score (4 or 5 out of 9). Routine monitoring of bodyweight is indicated (frequency to be individually tailored).
• Avoid scavenging and do not give table scraps.
• Although definitive evidence does not exist, in cases of suspected chronic pancreatitis, a low-fat diet and avoidance of treats (as some of them can have high level of fat) is recommended. If concomitant conditions are present or the patient is not keen on the available commercial diets, nutritional specialist advice should be considered for the formulation of homemade diets,which may be more palatable for some patients and/or meet multiple dietetic requirements.
• Medication: if we have a dog with history of acute/chronic pancreatitis or any evidence of possible pancreatitis on blood testing, before considering a drug reported to potentially cause pancreatitis, we should check if an effective alternative exists.