A problem with child class

[Truman]

class Dog():
	species = 'mammal'
	
	def __init__(self, name, age):
		self.name = name
		self.age = age
		
	def description(self):
		return f'{self.name} is {self.age}'
		
	def speak(self, sound):
		return f'{self.name} says {self.age}'
	
class RussellTerrier(Dog):
	def run(self, speed):
		return f'{self.name} runs {self.speed}'
	
class Bulldog(Dog):
	def run(self, speed):
		return f'{self.name} runs {self.speed}'
	
jim = Bulldog("Jim", 12)
print(jim.description())
	
print(jim.run("slowly"))

Error:
Traceback (most recent call last):
  File "C:\Python36\kodovi\dogparent.py", line 25, in <module>
    print(jim.run("slowly"))
  File "C:\Python36\kodovi\dogparent.py", line 20, in run
    return f'{self.name} runs {self.speed}'
AttributeError: 'Bulldog' object has no attribute 'speed'

I don't understand these errors:
1. Child classes have specific attributes and behaviors as well
2. Bulldog object has 'speed' within method run