The short answer: No.
The long answer: Belonging to the citrus family, lemons are highly acidic fruits that should not be consumed by dogs because of the psoralen compounds and essential oils found in them. Even just a small amount may harm small-sized dogs, which can lead to vomiting, diarrhea, weakness, gastrointestinal distress, and sensitivity to light. Even if the lemon fruit is edible for dogs, the peel, seeds, and plant itself are the most dangerous parts because they contain the highest levels of toxic oils.
Though it may be tempting to let your dog try lemon juice to get a funny reaction out of him or apply lemon essential oil on his fur to supposedly improve his health, these are highly inadvisable.
What to do if your dog accidentally eats lemons: Lemons can be lethal for dogs, especially if they consume large quantities of the fruit. Its highly acidic nature can disrupt a dog’s acid base balance. Aside from upsetting his stomach, the lemon peel or seeds can also obstruct his airway and/or intestines.
Call your vet if your dog accidentally eats lemons. Take him to the emergency clinic once he displays any of these symptoms: vomiting, nausea (in the form of constant lip licking and exaggerated swallowing), diarrhea, muscle tremors, inability to walk or stand, drooling, rashes in the groin area, and other unusual behaviour. If left untreated, severe cases may lead to liver failure or even death.
In summary: Lemons do not provide any nutritional benefits for your dog, so it’s best not to make him try this fruit, its juice, or its oil. You’re better off treating him with dog-friendly fruits such as apples, bananas, blueberries, kiwi, mango, pineapples, and watermelon.