Pets with rapid weight loss have prominent ribs and when you look down on your pet, you'll notice a sharply defined waist as the flanks cave in between the last ribs and the hip bones. Pets with unhealthy weight loss are also unable to reproduce, so female pets either do not become pregnant or do not carry their offspring to term.
With sudden, short-term weight loss in dogs and cats caused by dehydration rather than loss of fat, the eyes appear sunken, the skin tents when pinched and does not spring back quickly, there is little urine production, the stools are hard, and the mucous membranes covering the gums are tacky rather than moist. You may also notice the following symptoms if your pet has sudden weight loss:
Unhealthy weight loss is diagnosed by weighing your pet and assessing his or her physical appearance. Pets of a healthy weight have a layer of muscle and fat over their ribs so that each rib can be felt. Pets of a healthy weight also have a waist, or a narrowing in the flank area between the last ribs and the hip bones. If your pet is too thin, the ribs can be felt so easily that it is like running your hand along a washboard. Pets that are too thin also have an extreme waist so that the flank area between the last ribs and hip bones is deeply sunken.
If your pet is losing weight too rapidly, any of these may be the cause: dentition, dysgeusia (an abnormal or impaired sense of taste), diarrhea, disease, depression, dementia, dysfunction, drugs, or an unknown cause.
Over 75% of older pets have dental disease, which may include gum problems, sores in the mouth, swollen tonsils, and decaying teeth. Brushing is the best way to improve your pet's dental health. C.E.T. Enzymatic Toothpaste is poultry or beef-flavored and pets love it. Two minutes a day is all it takes.
Dysgeusia is an unusual or poor sense of taste. If your pet can't taste, he or she may actually have a problem with smelling food. If your pet has allergies, he or she may have a stuffed-up nose that makes it difficult to taste food.
Diarrhea causes weight loss because your pet loses water, vitamins, and calories.
Diseases that cause weight loss include ehrlichia (bacterial disease spread by ticks), Lyme Disease, diabetes, cancer, colitis, and painful arthritis. It is easy to understand how infections like ehrlichia and Lyme Disease can cause weight loss because sick pets burn more calories. Many diseases also cause pain. For example, Lyme Disease and ehrlichiosis cause painful arthritis that can discourage pets from getting up or from walking to their food bowl.
Upset, anxious or mourning pets may not have the spirit for eating.
Pets no longer able to think clearly don't eat as they should.
When the stomach, pancreas and intestines don't function well, your pet can't digest and absorb his or her food. Older pets often are unable to make the enzymes needed to absorb vitamins in their food, such as Vitamin B12. When the stomach and pancreas don't make the enzymes needed to break down proteins, fats, and carbohydrates, pets can't absorb these either.
Many drugs—from antibiotics to chemotherapy medications—cause nausea so that pets lose interest in eating.
If none of the above apply to your pet, it is possible your pet has worms. Intestinal worms are usually the culprit for "unknown causes" of weight loss in many pets. Recent analysis suggests routine testing for worms in the veterinary clinic misses 85% of the worms in the stool. In other words, fecal samples testing negative which were then sent to university pathology labs showed intestinal parasites 85% of the time. Worms rob your pet of nutrition and are among the easiest problems to remedy.