Hyperphosphatemia in Dogs
Written By hannah hollinger
Published: 01/26/2016Updated: 01/12/2022
Veterinary reviewed by Dr. Linda Simon, MVB MRCVS
Excess Phosphorous in the Blood in Dogs - Symptoms, Causes, Diagnosis, Treatment, Recovery, Management, Cost
What is Hyperphosphatemia?
Most phosphorous is stored in the bones, but a small percentage circulates in the blood-normally no greater than 6.0 mg/dL. Its role is in muscle contraction and nerve function, but levels of phosphorous are controlled by the kidneys under the parathyroid hormone (PTH). This hormone prevents levels from rising too high, so if the phosphorous levels are high in your dog, there is likely something wrong with their kidneys.
Hyperphosphatemia can happen to any dog of any age, but is most commonly seen in adolescent or elderly animals. It can be fatal in chronic cases and should be treated as such, but is never the exclusive cause of your dog's ill health.
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Symptoms of Hyperphosphatemia in Dogs
Hyperphosphatemia is always a marker of an underlying disease because elevated levels in the blood are considered a symptom itself. By itself, it will not cause any clinical symptoms. However, in chronic cases with high phosphorous levels, you may see:
  • Excessive thirst
  • Excessive urination
  • Muscle tremors
  • Muscle wasting
  • Seizures
  • Decreased bone density
Types
Hyperphosphatemia manifests as either an acute or a chronic case.
  • It is rare for the acute cases to create long-standing problems as these are most commonly caused by adolescent growth spikes. However, if the cause was due to poisoning, parasites or trauma, it is vital to get your pet to a veterinarian for treatment of the underlying cause.
  • In chronic conditions, symptoms will be manifesting over a long period and will give a better idea of the underlying cause, but will more severely affect their health and will present with more symptoms which may be alarming or dangerous in nature - as with muscle spasms and seizures.
Causes of Hyperphosphatemia in Dogs
The most common causes of this disease varies depending on the dogs age.
  • In older dogs, it is most commonly caused by renal failure, intracellular malfunction, a malfunctioning thyroid gland resulting in a decreased production of the parathyroid hormone or overactivity of the gland which results in weight loss and muscle wasting. It may also be linked to diabetes.
  • In adolescent dogs, it's often due to increased intestinal absorption and decreased renal absorption. It should be noted that phosphorous levels in young dogs - especially of large breeds will sometimes be greater than in adults because phosphorous is used to facilitate bone mineralization (hardening). This is normal.
    • In all age groups, it can be caused by dehydration, parasites, trauma, or poisoning caused by raisins/grapes or an excess of vitamin D.
Diagnosis of Hyperphosphatemia in Dogs
If your dog is displaying twitchy muscles, drinking an inordinate amount or is increasingly lethargic, it's important to get them to a veterinarian office. Be certain to give a thorough history of any symptoms to your veterinarian including duration of symptoms and additional diseases if applicable. Your veterinarian will then conduct a physical exam to determine what organs have been most affected.
In doing a diagnostic analysis, your veterinarian must first determine that your dog, in fact, has high phosphorous levels. This is typically done with a CBC or complete blood count, followed by a serum biochemistry panel and urinanalysis. It should be noted that an exacerbatory factor for hyperphosphatemia include problems with intracellular uptake of phosphorous. If a large number of blood cells die (hemolysis) during or after the blood sample is taken, these cells will release the mineral into the blood serum and therefore have the potential to give a false-positive high reading of phosphorous. For the pet owner, this means that more samples may be necessary to determine actual readings because hemolytic samples are not representative. The importance of this will matter most if your dogs readings are borderline.
Treatment of Hyperphosphatemia in Dogs
High levels of phosphorous due to malfunction of the kidneys or a decrease in the volume of plasma won't necessarily be of clinical significance. Treatment will depend a great deal on the cause of the hyperphosphatemia. If your dog has decreased parathyroid hormone levels, your veterinarian will discuss thyroid hormone therapy.
If the problem stems from renal (kidney) problems, this will first be treated with aggressive fluid therapy followed by a low phosphorous diet to treat a dog with chronically high phosphorous levels. It's also possible your veterinarian will prescribe phosphate binders to link free-floating molecules. Phosphorous and calcium bind to create your dog's bones, so in a dog with high levels of phosphorous, it is possible they will also need to minimize calcium intake. This is especially true of chronic cases because calcium binding with phosphorous in extraskeletal tissue can result in tissue mineralization. This can be fatal.
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Recovery of Hyperphosphatemia in Dogs
Visit your veterinarian regularly for checkups to evaluate treatment efficacy. This will usually include taking additional blood samples. Give your dog plenty of quiet and time to recover from an episode of high phosphorous levels. If the underlying cause was an acute case of Vitamin D over supplementation or ingestion of grapes or raisins with minimal damage to their renal system, your dog is likely to recover quickly. If your dog has a chronic condition involving their thyroid gland, renal retention, diabetes or cancer, your veterinarian will discuss a long-term prognosis and management program with you.
Hyperphosphatemia Average Cost
From 367 quotes ranging from $500 - $2,500
Average Cost
$1,400
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Hyperphosphatemia Questions and Advice from Veterinary Professionals
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Airedale Terrier
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Murphy
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5 Months
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My 5 month old grandog has been in the ICU for 7 days now. Initially diagnosed with ARF, etiology unknown. Creatinine has been going down, but, hypocalcemia and hyperphosphatemia continues. He is currently on continuous IV fluids with calcium carbonate, 2.5 ml/kg/day. Binders were just added yesterday. After 7 days, still no cause for the renal failure. Have any ideas how we can correct the calcium and phosphorus?
Nov. 4, 2017
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There are a few causes of hypocalcemia and hyperphosphatemia (acidosis, thyroid disorders etc…) but the renal failure would be the cause in this instance; it is important to address the renal failure, manage it and determine an underlying cause. Calcium supplementation is important but further investigation to an underlying cause is required. Regards Dr Callum Turner DVM
Nov. 4, 2017
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Pomchi
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Minnie
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4 Months
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My pet has the following symptoms:
Frequent Urination
My 4 month old puppy has had frequent urination since I have had her for 2 months. Sometimes her urine is clear & sometimes dark yellow. Urine collected at the vet was clear with no concentrate. She had bloodwork done and PHOS was 8.2+. The vet thinks the May have a congenital defect and does not think its a UTI however we are treating her with abx. Would elevated PHOS indicate anything? Other abnormal numbers were TP (5.3-) and GLOB (1.8-). Please help !
July 26, 2017
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Thank you for your question. Blood concentration of phosphorous of 8.2 mg/dL (reference 2.9 – 5.3 mg/dL) may be a normal finding in some young dogs to assist with bone development. However, increased phosphorous may be due to decreased kidney excretion, increased intestinal absorption or by hypoparathyroidism (which would also explain the frequent urination). Total protein of 5.3 g/dL is just below the 5.4 – 7.5 g/dL reference range and the globulins of 1.8 g/dL is outside of the reference range of 2.7 – 4.4 g/dL; usually protein loss from the kidneys or intestinal tract is by the loss of albumin not globulins (as the albumins are smaller in size). Generally, low levels of globulins may be caused by stress, parasites, systemic disease or breed predisposition. Without further information, I am unable to comment further. Regards Dr Callum Turner DVM
July 26, 2017
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Hyperphosphatemia Average Cost
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Average Cost
$1,400
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