Introduction
There are over 150 varieties of avocados worldwide, and in Kenya, we have over 40 varieties. Commercially, however, two varieties are cultivated and processed in Kenya - Hass and Fuerte avocados.
Eating avocado is linked with heart failure in mammals and birds and with sterile mastitis in lactating mammals. Cattle, goats, horses, mice, rabbits, guinea pigs, rats, sheep, budgerigars, parrots, canaries, cockatiels, ostriches, chickens, turkeys, and fish are susceptible to these conditions after avocado ingestion. Exotic birds seem more sensitive to the effects of avocado, whereas chickens and turkeys seem more resistant. Although a single case report of two dogs developing myocardial damage in Kenya after avocado ingestion exists, dogs seem relatively resistant compared with other species. Exotic birds and livestock exposed to avocado plants or fruits are at the greatest risk of avocado poisoning.
What is the Cause of Avocado Poisoning in Animals?
The whole of the avocado plant, i.e. the fruits, leaves, stems, and seeds have been associated with poisoning in animals, with leaves being the most toxic part. The poisonous part in avocado is chemically called persin.
This chemical causes the death of tissues within the mammary glands of milking animals and within the heart muscles of birds and mammals.
Persin is an antifungal toxin present in the avocado, and it leaches into the body of the fruit from the seeds. The ripe pulp of the avocado fruit has a low concentration of persin, so it is relatively harmless to humans, with negative effects in humans primarily being allergies. However, it is toxic and dangerous when domestic animals consume persin through the leaves or bark of the avocado tree or skins and seeds of the avocado fruit.
What are the signs of avocado poisoning in Animals
Sterile mastitis within 24 hours of ingestion of avocado, accompanied by a 75% decrease in milk production.
In non-lactating mammals, or after ingesting a large amount of avocado, heart failure develops within 24–48 hours of ingestion and may be characterized by:-
Lethargy
Respiratory distress
Oedema
Cyanosis
Cough
Exercise intolerance, and
Death.
Horses may develop oedema of the head, tongue, and breast region.
Birds develop lethargy, dyspnea, anorexia, and subcutaneous oedema of the neck and chest regions, and they may die.
How is avocado poisoning diagnosed in animals?
Diagnosis of avocado poisoning is mainly based on the history of exposure, clinical signs and clinical evaluation. There are no readily available specific tests that confirm the diagnosis.
How is avocado poisoning treated in animals?
Treatment is supportive and focused on managing clinical signs. Pain killers may benefit patients with mastitis caused by avocado toxicosis. In contrast, treatment for heart failure (e.g., diuretics, antiarrhythmic drugs) may benefit companion animals but may not be economically feasible in production animals. There is no antidote for avocado poisoning.
Can dogs eat avocados?
Dogs can eat avocados, however, in moderation. The avocado fruit has different levels of the poisonous chemical persin in different parts of the fruit with more in the seed and skin, and less in the pulp. The infographic below explains further.
Avocado Poisoning in birds
Some avian species, especially the exotic birds that are household pets, are usually susceptible to persin, the toxic chemical of the avocado fruit, through its ingestion. All parts of the avocado (Persea americana) plant are poisonous, i.e., the fruit, seeds, leaves, and bark.
Avocados of several species are lethal within 24 to 48 hours in budgerigars and parrots, demonstrating clinical signs such as lethargy, fluffed feathers, and increased respiratory effort.
The most consistent postmortem findings include fluid surrounding the heart, oedema and generalized congestion of organs, including the lungs and liver.
References
Buoro, I. B. (1994). Putative avocado toxicity in two dogs. The Onderstepoort journal of veterinary research, 61(1), 107-109. Retrieved from https://repository.up.ac.za/handle/2263/32329
Kathula, D. N. (2021). Avocado Varieties and Export Markets for Sustainable Agriculture and Afforestation in Kenya. Journal of Agriculture, 5(1). Retrieved from http://stratfordjournals.org/journals/index.php/journal-of-agriculture/article/view/739
Oelrichs, P. B., Ng, J. C., Seawright, A. A., Ward, A., Schäffeler, L., & MacLeod, J. K. (1995). Isolation and identification of a compound from avocado (Persea americana) leaves which causes necrosis of the acinar epithelium of the lactating mammary gland and the myocardium. Natural toxins, 3(5), 344–349. https://doi.org/10.1002/nt.2620030504
Samour, J. (2015). Avian medicine. Elsevier Health Sciences.