Intestinal impaction by sunflower seed shells in two raccoons in Quebec.
Sunflowers, native to North America, were first cultivated by First Nations, then used for silage as well as a source of grain for poultry. Today, sunflower seeds are one of the most important sources of edible oils in the world. Sunflower seeds are also quite popular with bird watchers who maintain feeding stations for wild birds. This seed is by far the most common food offered in bird feeders. These increasingly popular feeding activities have positive impacts for both the birds and the observers. However, in some cases, the availability of this food in large quantities can lead to health problems in wild animals.
Here we report the death of two raccoons associated with excessive consumption of sunflower seeds. These two raccoons were found in the Sherbrooke region (southern Quebec) in August and October. One of the raccoons was found dead, the other exhibited abnormal behaviour and was euthanized for humanitarian reasons. In both cases, impactions with sunflower seed shells were present in the large intestine (two clusters respectively 10 and 15 cm long in one case, and a 15 cm long in the second case). The intestinal portions upstream of these impactions were dilated. These intestinal impactions were made up of extremely compact clumps of sunflower seed shells completely blocking the intestinal segment. These intestinal impactions were identified as the cause of death and clinical signs observed in these raccoons.
As far as we know, this type of intestinal impaction from the shells of sunflower seeds has not been reported in raccoons. However, many cases of impactions from the shells of sunflower seeds have been described in dogs and in people. These cases are usually linked to an excessive consumption of sunflower seeds (with shells). These shells, which are composed of cellulose and lignin, cannot be digested by mammals with simple stomachs. When ingested in very large quantities, they can accumulate and form compact masses in the intestine, called bezoar. Unlike carnivores or omnivores, granivorous species (like seed-eating birds) have a digestive system adapted to this type of food items. First of all, their beak is made to shell the seeds. They also have a gizzard (the muscled part of the stomach) capable of grinding the seeds and their shells. Therefore, they are not at risk of developing obstructions of the intestinal tract by shells. Rodents, like chipmunks and squirrels, also shell the seeds with the help of their incisors, limiting their shell ingestion.
It can be proposed that these two raccoons had access to a very high quantity of sunflower seeds, either directly from a high capacity bird feeder, or from unsecured sunflower seed bags. It is important to mention that the ingestion of a small quantity of sunflower seeds that would have fallen from a bird feeder would likely not represent a health risk to raccoons. These two cases show the importance of securing our reserves of seeds and to make sure bird feeders are not accessible to raccoons. In the eventuality that these feeders are potentially accessible, it is better to avoid overfilling them. Bird feeding is an activity that is gaining in popularity, allowing us to nurture our interest for the conservation of the peri-urban fauna. That being said, it is advisable to take certain measures that will minimize the negative impacts of this practice on the health of wildlife.
Manatakis DK, Acheimastos V, Antonopoulou MI, Balalis D, Korkolis DP. Gastrointestinal seed bezoars: A systematic review of case reports and case series. Cureus. 2019;11(5):e4686.
Eitan A, Bickel A, Katz IM. Fecal impaction in adults: report of 30 cases of seed bezoars in the rectum. Dis Colon Rectum. 2006 Nov;49(11):1768-71. doi: 10.1007/s10350-006-0713-0. PMID: 17036204.
Gouvernement du Canada. La biologie de l’Helianthus annuus L. (tournesol). Modified 2015-02-04. Available at: https://inspection.canada.ca/varietes-vegetales/vegetaux-a-caracteres-nouveaux/demandeurs/directive-94-08/documents-sur-la-biologie/helianthus-annuus-l-/fra/1330977236841/1330977318934#shr-pg0