On the third day of food deprivation the dog’s metabolism slows down. This lower, or slowed, metabolic rate continues as long as no food is consumed. The lowered metabolism is a survival mechanism to decrease the utilization of body fat and muscle for energy. Lowered blood sugar levels changes insulin secretion by the pancreas, which in turn lowers thyroid hormone levels; and it’s the thyroid gland function that ultimately dictates the metabolic rate.
During starvation the liver releases chemicals called ketones into the blood stream; ketones are then used as a source of energy for the dog’s body cells. By creating ketones and fatty acids to be used as energy sources, the dog’s body conserves what little glucose is circulating so that glucose-dependent red blood cells and important kidney tissues can continue to access glucose. Interestingly, red blood cells and kidney tubule cells cannot utilize anything other than glucose for cell energy needs.
After five days of starvation fat becomes the main source of energy.
Animal caretakers must exert strict self-control when attempting to nurse a starved dog back to good health. The natural and common tendency is to overfeed the dog "because he’s ravenous." If an emaciated and starved dog is suddenly overfed serious consequences, such as refeeding syndrome, await. This is because a sudden load of carbohydrates in a large meal can create serious shifts in potassium and phosphorus concentrations in all body cells.
Signs of Refeeding Syndrome are described as muscle weakness, muscle cramps, heart muscle damage and rhythm irregularities, seizures, red blood cell rupture and respiratory failure.
In addition, a prolonged lack of food does not "shrink the stomach," but it does make the stomach much more sensitive to stretch receptor nerve impulses. The dog may feel as if full when the stomach has only a small quantity of food in the stomach. The increased sensitivity to gastric expansion will dissipate over 3 to 7 days.
The food being fed to the starved dog should have adequate mineral composition, especially phosphorous, potassium and magnesium. (Therefore, do not be tempted to feed, for example, just hamburger, which does not have a wide or balanced mineral content.) The amount of food, or total calories, should not exceed over 24 hours what the dog would normally eat at its normal weight. An emaciated dog is best served consuming a small meal every six hours (4 times a day) rather than consuming one or two larger meals.
A broad-spectrum vitamin and mineral supplement is important to include at each meal. Some evidence supports the addition of the amino acid glutamine to the recovery diet. Omega 3 and 6 fatty acid supplements are also beneficial to a dog recovering from malnourishment; the same holds true for the amino acid arginine. Dietary nucleotides are important contributors to the formation of DNA and RNA and assist in a number of metabolic activities of healthy cells. Diets rich in meat provide adequate nucleotides.
By feeding a highly digestible, meat-based "Puppy" or "Growth" food, along with certain supplements, recovery and weight gain should be evident in a short period of time -- that is, as long as the dog has a normal appetite.
Also, until a normal appetite should return, it is recommended to divide the daily suggested amount of food (based on the dog's estimated health weight) into four smaller portions. At each meal, closely monitor the dog's intake and note it on a chart. For example, the record could state, 8:00 a.m. meal - ate 100% or ate 50% or ate 10%.
If, after two days, the dog does not consume an amount over a 24-hour period approximately equal to the amount expected to be eaten by a healthy dog of the patient’s ideal weight, assisted (forced) feeding may become necessary. Consult your veterinarian regarding how best to force feed the patient.
Keep in mind that some dogs raised on a single type of dog food may reject a different type no matter how hungry the dog may be. There are dogs that simply refuse to eat canned food, dry food or table scraps, so be prepared to be creative. Slightly warming the food or moistening with chicken broth, and presenting the food in tidbit amounts can tempt a reluctant appetite.
If you estimate the dog has been deprived of food for 7 days or more, the diet should be composed predominately of fat rather than carbohydrates. Never allow the dog, especially early in the recovery feeding process, to consume a large meal all at once. Small amounts fed at intervals during the first few days is very important. Free access to water is proper.
It is common to see occasional vomiting or loose stool in the early recovery time of a starved dog. By weighing the dog twice a day (a.m. and p.m.) and by noting the amount of food ingested versus the amount vomited and passed as feces, an assessment can be made regarding positive or negative weight gain. Veterinary care is needed if bloody stool or vomit is noted or if there is weight loss during the refeeding and recovery period.