Rabbits need an unlimited supply of fresh water to stay hydrated and healthy. A hot day may temporarily cause your rabbit's thirst to increase, but if he's drinking an excessive amount of water under normal conditions, which you'll evidence by the amount of liquid left in his water bottle when you freshen it daily, he could be suffering from a specific illness. Always consult a veterinarian regarding the health of your pet.
Renal failure, a condition in which the kidneys fail to work properly, can impact rabbits at any age. According to the Pet MD website, a variety of reasons cause the illness, from trauma to heart failure. One of the telltale signs that the organ is malfunctioning is excessive thirst. The disease also typically causes increased urination, which incites the rabbit's body to try to compensate for the loss of fluid by increasing his desire for water.
Diabetes, a disease caused when the pancreas becomes dysfunctional, is not common among the rabbit species, but it does occur. Hyperglycemia, a condition characterized by high blood glucose levels, accompanies the disease, as does excessive thirst. Blood and urine tests can determine if the condition is present. Left untreated, diabetes can negatively impact the function of other organs, including the rabbit's liver and kidneys.
Excessive thirst is a common signal that your rabbit could have something wrong with his urinary tract. Disorders can include bladder infection, which can be confirmed if bacteria is found in the urine. Kidney or bladder stones, formed when high levels of calcium deposits merge, can cause incontinence, which leads to increased thirst and water intake.
An overabundance of sodium chloride, salt, in a rabbit's diet can increase his desire for extra water to flush the drying element out of his system. Likewise, an absence or extremely low level of fresh vegetables in his diet can make the rabbit extra-thirsty. Leafy greens like romaine lettuce and spinach can help keep your rabbit's fluid intake on the higher side, thereby curbing his need to drink to excess.