FIV severely weakens a cat's immune system, making them vulnerable to secondary infections. This disease is passed on from cats to cats through bite wounds, making outdoor cats who engage in fights susceptible to FIV. Symptoms of FIV may not be apparent at first and may even first develop years after the initial infection. There is no cure for FIV but infected cats can live healthy lives with proper medical interventions and it is important to recognize early signs of FIV.

Common symptoms include:

• Fever
• Recurring or chronic infections
• Gingivitis
• Loss of appetite
• Poor coat condition

Feline Leukemia Virus (FELV+) is a retrovirus that causes cancer in cats. It is highly infectious and can be passed on from cat to cat via cats' urine, blood, saliva, or feces. The most common way of transmission is through infected mothers to their offspring at birth or through contact with infected cats. FELV+ can severely weaken a cat's immune system, causing anemia and making cats vulnerable to other diseases. Infected cats have to be kept separate from healthy cats. There is no cure for FELV+ but cats can live normal and prolonged lives with medication.

Common symptoms include:

• Recurring fever
• Recurring diarrhea
• Various eye conditions
• Various infections
• Loss of appetite
• Vomiting
• Weight loss

Ear mites are parasites living in cats' ear canals. This disease can be easily treated through proper medication.

Common symptoms include:

• Abnormal scratching of ears
• Red and inflamed ears
• Excessive head shaking

Feline diabetes is similar to diabetes in humans in which individuals are unable to produce insulin or have a proper response to insulin. Feline diabetes can be caused by a variety of factors such as genetics, obesity, an increase in age, pancreatic disease, and physical inactivity. Although feline diabetes is a serious health concern, it can be treated and successfully managed with medical intervention.

Common symptoms include:

• Weight loss
• Increased appetite
• Excessive thirst and urination
• Dehydration
• Fatigue

Feline calicivirus and feline herpesvirus are highly infectious viruses that cause upper respiratory diseases and are prevalent in multi-cat households and shelters. These viruses can be passed on from cat to cat through coughing, sneezing, and sharing of food and water bowls. Once infected, a cat becomes a carrier for life and is capable of infecting other cats even though no symptoms are shown. Infected cats are also susceptible to secondary infections.

Common symptoms include:

• Sneezing
• Fever
• Drooling
• Excessive discharge from eyes and nose

Ringworm is a fungal infection that is developed through direct contact with the fungus Microsporum canis. This fungus is easily spread in the environment and often infects cats. Ringworms can be easily treated with oral and topical medication.

Common symptoms include:

• Hair loss in patches
• Excessive grooming
• Inflammation
• Scaly and dry skin

Hyperthyroidism is caused by an increased production of thyroid hormones from an enlarged thyroid gland on a cat's neck. Hyperthyroidism typically affects middle-aged or older cats. Specific causes of hyperthyroidism are unclear but environmental factors and high dietary iodine composition are hypothesized to be causative factors. Oral medication intervention can effectively lower thyroid levels and enable cats to live a normal life.

Common symptoms include:

• Restlessness
• Excessive energy
• Weight loss
• Increased appetite