Owners of typically well-behaved, good-humored dogs should suspect a medical condition if their dog behaves aggressively in unexpected ways or slowly but steadily. Medical requirements should also be suspected in stray dogs or rescued puppies with unknown medical histories. But not all owners are willing to give these dogs the benefit of the doubt, either ignorance or fear. The truth is that an aggressive dog is a scary dog, primarily if the aggression is directed at other animals, children, and people. Such puppies are considered a burden, a creature too dangerous to handle, smoothly going from man’s best enemy to man’s worst enemy. One of the best solutions is you need to perform dog training. A much-loved puppy has become a grumpy creature ready to bite. While many canine aggression cases are behavioral, it would be unfair to assume this without trying to rule out a clinical reason. Below are some medical issues that could exist from aggressive dogs;
Chronic Pain
Spine and throat problems can cause aggression when you touch your puppy’s collar to put him on a leash. Chronic conditions, such as arthritis and hip dysplasia, can cause irritable behavior. For example, a dog with arthritis may react when he lies down and feels he can’t get out of an irritating situation, such as harassing a child. A recent study showed that sudden bursts of aggression are often associated with pain.
Hypothyroidism
This condition, which affects the endocrine system of puppies, results from deficient levels of thyroid hormones. Affected dogs often show weight gain, hair loss, lethargy, decreased cold tolerance, and behavioral changes such as stress, aggression, and anxiety. It is quite rare for a dog to experience charge for an isolated symptom when they have this disease; however, a thyroid evaluation remains worthy.
Seizures 
Dogs may develop competitive behaviors in the postpartum period after a seizure. Partial seizures in dogs that affect a specific part of the brain responsible for controlling aggression can also contribute to aggression and abnormal behaviors. However, when dogs are experiencing seizures, it could affect other severe diseases. It is essential to recognize some primary symptoms of this. Therefore, you can prevent some unexpected things you don’t want.
Brain Damage
Trauma that affects specific areas of the brain can cause neurological symptoms such as aggressive behavior. It can occur after the puppy has suffered brain damage. Brain cancer, which is common in older dogs, can be another cause of such behavioral changes. Encephalitis, inflammation of the brain, can cause significant aggression in affected dogs. Rabies and distemper are types of encephalitis. Hydrocephalus, a congenital condition in which the brain’s ventricles become enlarged, can cause a variety of neurological disorders that occasionally include aggression.
