Kidney disease is an all-encompassing term for a breakdown in kidney function. Causes of kidney disease in dogs include, but are not limited to, cancer, parasites, autoimmune disease, toxic substances and trauma. Kidney disease is also caused by a dog's genetics and can be nothing more than an age-related illness. If untreated, kidney disease leads to some serious physical repercussions like a slow poisoning of the blood that can be fatal.
When kidney disease progresses, a dog's abdomen will begin to swell as the kidneys become filled with fluid. Diseased kidneys cannot push fluid through to the urinary tract as they should and begin to retain any fluid that is passed through. Swelling may also occur in a dog's legs as the circulatory system becomes stalled by the lack of movement through the kidneys. This may occur fairly early in the disease but will be more obvious during the end stages.
Change in Urination
Kidneys are filters for the body, meant to filter toxins out of the blood and send them on to the urinary tract. Diseased kidneys cannot perform this function, so there is a build-up of toxins in the blood. The dog's thirst will become exaggerated as the body tries to flush the toxins from the system in alternative ways. Increased urination follows. Conversely, the lack of movement through a dog's kidneys may result in decreased urination, regardless of how much water the dog is drinking. The fluid may stay in the kidneys or be passed into the ankles. This can also result in bloody urine as the kidneys struggle to perform their function. These symptoms become more obvious as the kidney disease reaches its final stages.
Depression and Fatigue
As a dog's kidneys fail, toxins become more and more concentrated in the blood and lead to a slow poisoning effect. This causes fatigue, depression, lethargy and diarrhoea. This aspect of kidney disease is exacerbated by a hormonal imbalance. Kidneys generally release erythropoieten, which signals the dog's body to produce red blood cells. Lack of erythropoieten leads to a lack of oxygen circulation in the dog's body that results in further lethargy. This is akin to a dog's body starving for air.
Vomiting and Nausea
As the lack of filtration in a dog's blood poisons its body, it becomes increasingly difficult for the dog to keep down any food or garner nutrition from that food. This results in nausea, vomiting and weight loss. Despite the swollen abdomen, which is the result of the kidneys retaining water, a dog will become noticeably thinner in the final stages of this disease,will be unable or unwilling to eat and will vomit consistently. This lack of nutrition and constant nausea will increase a dog's depression and lethargy.