What medical conditions cause aggression in dogs

When the once gentle and clingy fur baby suddenly bares its teeth at you or launches unprovoked attacks on other people and animals, you are filled with shock and heartache. You can’t help but wonder, what happened to the former little angel? Behind a dog’s aggressive behavior, in addition to behavioral habits and environmental factors, there may also be the "dark hand" of disease lurking. These diseases torture the dog’s body and disrupt their emotions, making it impossible for them to remain as friendly and gentle as before. Every abnormal attack is a distress signal from the dog, and what we need to do is to use professional knowledge and warm love to lift the fog, identify the cause of the disease, and help them regain health and happiness.

Neurological diseases are one of the important causes of aggressive behavior in dogs. As a common neurological disease, epilepsy can cause sudden symptoms such as convulsions and confusion in dogs. Before and after an epileptic seizure, dogs may be in a state of irritability and restlessness, extremely sensitive to their surroundings, and even slight stimulation may trigger their aggressive behavior. Imagine a dog that has not fully regained consciousness after an epileptic seizure. If someone approaches at this time, it may perceive the other party as a threat and launch an attack due to fear and discomfort. In addition, encephalitis can also seriously affect a dog’s neurological functions. Brain inflammation can cause mental confusion and abnormal behavior in dogs, and a once gentle dog may become irritable and even take the initiative to attack people and animals around it. Dogs that exhibit aggressive behavior due to neurological diseases are like "little warriors" trapped by illness—unable to control their actions and perhaps filled with fear and helplessness inside.

Pain-induced aggression is also common in dogs. Arthritis is a high-incidence disease in senior dogs and large breeds. As joint cartilage wears down and inflammation worsens, every step and movement a dog makes is accompanied by pain. When their affected joints are touched or when someone tries to force them to exercise, they will instinctively protect themselves through aggression to avoid increased pain. Just as humans resist being touched when injured and in pain. Injuries and illnesses such as toothaches and fractures can also put dogs in pain. A dog with severe toothache is likely to suddenly bite when its owner tries to examine its mouth. For these dogs tortured by pain, their aggression is not malicious but a cry to their owners: "I’m in so much pain, don’t touch me!"

Endocrine disorders can also cause aggressive behavior in dogs. Hypothyroidism causes insufficient thyroid hormone secretion in dogs, affecting metabolism and neurological functions. Affected dogs may become lethargic and slow to respond, but sometimes they can suddenly become grumpy and exhibit aggressive behavior. Cushing’s disease (hyperadrenocorticism) increases cortisol levels in dogs, leading to emotional instability, excitability, and anger. Dogs with endocrine disorders are like "small machines" with internal malfunctions—unable to control their emotional changes, their once gentle personalities quietly altered by the disease.

Some infectious diseases can also affect a dog’s behavior. Rabies is a fatal zoonotic infectious disease. In the early stages of the disease, dogs may exhibit personality changes, restlessness, and other symptoms. As the disease progresses, they enter a manic phase, characterized by strong aggression and active attacks on people and animals. Although the popularity of rabies vaccines has greatly reduced the incidence of rabies, once the disease develops, the mortality rate is almost 100%, and every case of rabies is deeply distressing. Canine distemper virus not only affects a dog’s respiratory and digestive systems but can also impact the nervous system, causing symptoms such as convulsions and abnormal behavior. Some affected dogs may also exhibit aggressive behavior.

When noticing aggressive behavior in a dog, owners must not ignore it or simply dismiss it as the dog being "disobedient." First, carefully observe whether the dog has other abnormal symptoms, such as fever, vomiting, diarrhea, lameness, or listlessness—clues that are crucial for determining the cause. Then, promptly take the dog to a veterinary hospital. Veterinarians will use detailed consultations, comprehensive physical examinations, blood tests, imaging studies, and other professional methods to accurately identify the root cause of the dog’s aggressive behavior. Only by confirming the cause can targeted treatment be administered.

During treatment, the owner’s companionship and care are essential. For dogs that attack due to pain, administer pain medication strictly according to the veterinarian’s instructions to relieve their suffering; for dogs with neurological diseases, provide a quiet and comfortable environment to reduce stimulation; for dogs with infectious diseases, implement isolation measures to prevent disease transmission. Every medication dose and every care routine reflects the owner’s deep love and reluctance for the dog. How we hope these little ones can soon break free from the shackles of illness and return to their carefree, gentle, and lovely selves.

Dogs accompany us throughout their lives. When they are tortured by illness and unable to control their behavior, we become their only support. Understanding the helplessness behind their aggression and using professional medical care and warm love to dispel the haze of disease is not only a responsibility but also a testament to the deep bond between us and our dogs. May every dog troubled by illness, under the protection of their owners, overcome the disease and once again wag their tails and run toward a life filled with sunshine.