Oxalate salts in star fruit are absorbed by your dog’s intestinal tract and attach to the calcium, which causes an abrupt decrease in calcium. This can cause acute kidney failure, which presents with vomiting, diarrhea, blood in the urine, and excessive thirst and urination. Small breed dogs, neutered males, those that are overweight or do not exercise, and those with a dry food only diet, are more susceptible than others. Another way that the calcium oxalates in starfruit can damage the kidneys is the oxalate crystals that build up over time with high levels of calcium oxalate (hyperoxaluria). The oxalate and calcium bind together and become absorbed by the kidneys, causing inflammation and calcification. Small or toy breed males are more susceptible due to them not drinking as much water as larger dogs do. Obesity, lack of exercise, being neutered, and a dry food diet are all risk factors for calcium oxalate stones.

Star Fruit poisoning in dogs is a serious condition that can cause acute kidney injury even if eaten in small amounts. In fact, less than one ounce (half of a starfruit) is enough to make your dog ill because of the soluble calcium oxalate it contains. 

Your dog may start showing signs of star fruit poisoning within one to six hours of ingestion. The first things you will notice are vomiting and chronic hiccups, progressing to more severe symptoms depending on how much starfruit your dog actually consumed. In moderate to severe poisoning neuropsychiatric symptoms will begin, such as confusion, agitation, and seizure. This can advance to coma and possibly death if not treated. Some of the most common signs of star fruit poisoning are:

Star Fruit poisoning is caused by eating starfruit. The exact amount of fruit your dog can safely eat is not known, but toxicity has been reported with just one ounce (half of a star fruit), so it is best not to give it to your dog at all. Some dogs are more at risk than others such as those of small breed.

The veterinarian will do a physical examination, carefully checking your dog’s heart and breath sounds for abnormalities or fluid in the lungs. Your dog’s heart rate, reflexes, blood pressure, weight, height, body temperature, and abdominal palpation will be checked for any abnormalities as well. Give the veterinarian as much information as you have about what your dog ate and when, the symptoms you have seen, and any injuries or illnesses that you have noticed lately.

A complete blood count (CBC), arterial blood gas, biochemistry profile, urinalysis, BUN, and creatinine levels will be done. Creatinine levels will increase dramatically, and urinalysis will show elevated levels of protein and calcium oxalate crystals. Both radiographs (x-rays) and an ultrasound of the kidneys will show the presence of calcium oxalate stones or crystals as well as any damage that has already been caused. The veterinarian may also want to do a kidney biopsy to get some tissue for a microscopic examination.

The treatment for star fruit poisoning is determined by how much your dog has eaten and his condition. For example, if your dog is having signs of kidney failure (abnormal output of urine, excessive thirst, depression), the veterinarian will first want to make sure he is stable. The veterinary team will likely admit your dog to the hospital for IV fluid therapy to help flush the toxins out your dog’s system since his kidneys are not able to do the job. In addition, urine output will be measured to watch for declining urination. If urine output declines too much, they will treat your dog with hemoperfusion or hemodialysis because peritoneal dialysis is not effective with this kind of poisoning. However, many veterinarians prefer to use a laser technique (lithotripsy) to break up the calcium stones or crystals so they can be flushed out with saline solution.

Prognosis depends on the amount of star fruit eaten and how soon treatment was administered. If the treatment was started before any serious kidney damage is done, your dog’s prognosis is good. However, if kidney damage has been substantial and treatment is not effective, your dog will need a kidney transplant to survive longer than a few months. This type of poisoning can be prevented by not leaving any starfruit where your dog can get it.