Avian Nutrition:
Nutritional management of renal disease

Author: Christal Pollock, DVM, Dipl. ABVP-Avian

Date: May 22, 2007

Keywords: Renal disease, renal failure, vitamin A, hypovitaminosis A, protein, calcium, gout, vitamin D, cholesterol, pellets, formulated diets, omega-3 fatty acid, omega-6 fatty acid.

Key Points

• Recognize and correct nutritional imbalances that may promote the development of renal lesions such as hypercalcemia, hypervitaminosis D, vitamin A deficiency, and excessive dietary cholesterol or protein.
• There are many theories on the pathogenesis of gout, however elevated dietary protein alone does not appear to be the cause of gout since diets as high as 70% protein failed to induce gout in adult cockatiels.
• The initial diet fed to the patient with renal disease should be high in carbohydrates and fat to provide energy and calories.

Introduction

There are a wide variety of potential causes of renal disease in the avian patient. Ideally, definitive diagnosis should guide nutritional management of renal disease. Of course even when a definitive diagnosis has been identified, there often more questions than answers for care of the bird with renal disease.

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Nutritional causes of avian renal disease

There are a number of potential nutritional problems that can promote renal disease. Excess dietary protein, excess dietary calcium, hypovitaminosis A, or hypervitaminosis D may lead to nephritis or other degenerative renal changes.

1. Profound hypovitaminosis A causes squamous metaplasia of ureteral mucosa and collecting ducts leading to blockage of the ureters and secondary hydronephrosis, hyperuricemia, and oliguric or anuric renal failure.
2. Excess dietary protein has been theorized to play a role in gout, however research to date has not supported this theory. First, 60-80% protein was required to induce gout in genetically predisposed chickens, and there was no evidence of gout in adult cockatiels fed up to 70% protein for 11 months. Abrupt changes in high protein diets have also been theorized to lead to uricemia and secondary gout.
3. High calcium intake has been directly correlated with renal conditions in birds such as nephrocalcinosis, gout, and nephrosis.
4. Excess vitamin D3 promotes metastatic mineralization of viscera including the kidneys. This problem most commonly affects nestling parrots. Clinical signs may include polyuria, polydipsia, anorexia, crop stasis, and weight loss.
5. Cholesterol supplemented in pigeon feed induced significant renal lesions.

There have also been anecdotal reports of “diet-induced” renal disease syndrome in small companion parrots fed predominately pellets. Affected species have been small color variety psittacines such as cockatiels (Nymphicus hollandicus), lovebirds (Agapornis spp.), budgerigar parakeets (Melopsittacus undulatus), and parrotlets (Cyclopsitta spp. and Forpus spp.).

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Nutritional management of renal disease

1. Ensure adequate hydration.
2. Recognize and correct nutritional imbalances (vitamin A, calcium, protein) as needed. Vitamin A may be supplemented at 2000-5000 IU/kg IM, repeated in 1 to 3 weeks as needed.
3. Granivorous or nectarivorous patients in renal failure may benefit from a diet high in fat and carbohydrates such as Emeraid Psittacine™.
4. Other general recommendations for the patient in renal failure include low dietary protein, potassium, phosphorus, and sodium. However the concept of protein restriction is controversial in avian medicine, particularly for granivorous species. Although low protein diets may relieve some clinical signs of renal failure such as nausea, protein-energy malnutrition is prevalent in renal patients, and this problem is considered a significant predictor of death. If one elects to place a patient on a low protein diet such as Roudybush AK Renal Care™, monitor the patient carefully.
5. Some anecdotal reports suggest that small color variety parrots on 100% formulated diet, should be changed to whole grains, fruits, and vegetables until 3 to 6 months after resolution of clinical signs. Afterwards, pellets may be cautiously added back to the diet at a proportion of less than 50%.

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Omega-3 fatty acid supplementation

In mammals, omega-3 polyunsaturated fatty acids may help to preserve renal function and delay the progression of conditions such as glomerulopathy, nephrosis, or renal fibrosis. The exact mechanism of action is unknown. Ratios of omega 6:omega 3 should range from 4-5:1 to 1:3. Levels of omega-3 polyunsaturated fatty acid are abundant in flaxseed oil and fish oil. Vegetable oils such as corn oil are rich in omega-6. In avian patients, supplementation is recommended for at least 3 to 6 months or more at an oral dose of 0.22 ml/kg. Fatty acid supplementation may be combined with oral aspirin (0.5-1.0 mg/kg q12h).

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References

Echols MS. Evaluating and treating the kidneys. In: GJ Harrison, TL Lightfoot (eds). Clinical Avian Medicine Volume II. Spix Publishing, Palm Beach, Fl. Pp. 451-491, 2006.

Kamphues J, Otte W, Wolf P. Effects of increasing protein intake on various parameters of nitrogen metabolism in grey parrots (Psittacus erithracus erithracus) Abstracts of the First International Symposium on Pet Bird Nutrition. Hannover, Germany; 1997. P. 118

Koustos EA, Matson KD, Klasing KC. Nutrition of birds in the order Psittaciformes: a review. J Avian Med Surg. 15:257-275, 2001.

Pollock CG. Diagnosis and treatment of avian renal disease. Pp. 107-128.