Exotic mammal renal disease: causes and clinical presentation.

Renal disease is not uncommon in exotic mammals, with degenerative,infectious (bacterial, viral, parasitic), metabolic, nutritional,neoplastic, anatomic, and toxic causes all represented. This article discusses the clinical presentation for the various renal diseases affecting exotic mammals. Anatomic pathology at the gross and microscopic level is reviewed, as is disease pathophysiology unique to the species under discussion.     

Diagnosis and treatment of avian renal disease.

Reports on the incidence of renal disease in the avian patient vary,but renal disease is common in poultry and birds of prey. Clinical renal disease is probably under-recognized in the companion bird,with the notable exception of renal tumors in the budgerigar (Melopsittacusundulatus). Diagnosis of renal disease may rely on the identification of consistent clinical signs, clinical pathology, survey radiographs, and laparoscopic evaluation and biopsy of the kidneys.Treatment of avian renal disease relies on supportive care such as fluid therapy and nutritional support. Other treatments vary with the underlying cause and the clinical picture but may include systemic antibiotics, diuretics, parenteral vitamin A, and agents to lower uric acid levels such as allopurinol.     

Renal tubular necrosis and interstitial hemorrhage ("turkey-egg kidney") in a circovirus-infected Yorkshire cross pig.

A juvenile Yorkshire cross pig with rapidly progressive acute renal failure was submitted for necropsy. There was marked edema and disseminated petechiation of both kidneys, producing the "turkey-egg" appearance that is characteristic of exotic diseases such as African and classical swine fever. Microscopic findings included renal tubular epithelial necrosis with extensive interstitial edema and hemorrhage; lymphoplasmacytic, eosinophilic, and histiocytic tubulointerstitial nephritis; and numerous botryoid intracytoplasmic inclusions within the renal tubular epithelium and interstitial macrophages. Porcine circovirus 2 (PCV2) was readily identified within these lesions by both PCV2-specific immunohistochemistical staining and electron microscopy. Tests for African and classical swine fever viruses, as well as bacterial cultures, were negative. The striking renal lesions in this pig were attributed to PCV2 infection and are distinct from those that are typical of other PCV2-associated diseases.     

Emergency Presentations of Exotic Mammal Herbivores

Companion exotic mammal herbivores may be diagnosed with chronic disease that the owner believes is causing acute clinical illness. It is generally believed that because of the enhanced disease-masking ability of these “prey” species, numerous disease states may go unnoticed for a significant period. A veterinarian should be knowledgeable about this behavior trait and consider its possible effects when assessing the patient's health status. In some cases, the chronic disease condition may respond rapidly to treatment, whereas with other diagnoses, treatment is more frustrating. This article describes a selection of chronic disease conditions that one may diagnose in guinea pigs (e.g., hypovitaminosis C, trixacariasis, urolithiasis, dental disease), chinchillas (e.g., dental disease), and rabbits (e.g., dental disease, renal failure, cranial thoracic mass disease). Gastrointestinal and cardiovascular disease problems diagnosed in companion exotic mammal herbivores are covered elsewhere in this journal issue.     

Adult-onset hypothyroidism in a lynx (Lynx canadensis).

A 19-yr-old female lynx (Lynx canadensis) presented for an acute onset of anorexia and reluctance to move. Physical examination, radiography, hematology, and serum biochemistry revealed evidence of renal failure, presumptive uremic gastritis, chronic intervertebral disk disease at T13-L1, and markedly low serum levels of total thyroxine (1.54 nmol/L) and total triixodothyronine (0.55 nmol/L). Twenty-five hours after its original presentation, the lynx exhibited horizontal nystagmus, which has been suggested as a clinical sign associated with hypothyroidism in domestic dogs. The lynx was euthanatized because of poor prognosis, and medical management concerns related to its chronic renal failure. Necropsy examination substantiated that the lynx had true hypothyroidism with 60-90% of the thyroid gland replaced with adipose tissue. Although feline adult-onset hypothyroidism may have low incidence, it should still be considered as a cause of nonspecific signs of disease in cats, as well as signs suggestive of hypothyroidism. Routine monitoring of baseline exotic felid thyroid levels throughout life would help to identify normal values and diagnose a potential disease that has obscure clinical signs.     

Use of radiographs and computed tomography for measurement of kidney size in healthy chinchillas (Chinchilla lanigera)

BackgroundChinchillas, being small mammals, are subject to many of the urinary disorders that affect other companion animals. In cats and dogs, relationships between renal length and the presence of renal pathology have been well documented through the use of diagnostic imaging. Radiography and computed tomography (CT) are two commonly utilized diagnostic imaging modalities for assessing renal pathology. Presently, there are no published data on chinchilla kidney size and appearance using radiography or CT. This study aimed to determine healthy adult chinchilla renal size and correlate renal size to L2 body length and aortic diameter by use of radiography and CT.MethodsTwenty-eight healthy adult chinchillas with no clinical evidence of renal disease were placed under sedation for acquisition of radiographs and CT imaging. Both kidneys were measured on the radiographic views (right lateral, left lateral and ventrodorsal), when identifiable. Renal length, L2 body length and abdominal aortic diameter were measured on CT multiplanar reformatted images in specified planes and windows.ResultsIn 25% (7/28) of chinchillas, the renal length of either kidney could not be obtained on any of the three radiographic views due to superimposition of fluid and ingesta within the alimentary tract. Both the right and left kidney were identified on CT images in 100% of chinchillas (28/28). The left renal and right renal 95% confidence intervals from the dorsal plane CT images were 2.26 – 2.33 cm and 2.31 – 2.39 cm, respectively. No correlation was found between kidney length, L2 body length and diameter of the abdominal aorta on CT images.ConclusionsBased on dorsal plane CT imaging, normal chinchilla renal length is proposed to be between 2.25–2.4 cm.Clinical RelevanceRadiographic evaluation of chinchilla renal length is greatly limited due to their large fluid- and ingesta-filled colon and cecum, as is typical of animals that are hindgut fermenters. Through establishment of a normal CT reference interval for renal length and the ever-increasing clinical utility of CT, clinicians can better evaluate chinchilla renal length and identify alterations that may indicate pathologic processes.     

Renal dysplasia and urinary tract infection in a Bull Mastiff puppy

Renal dysplasia and concurrent pyelonephritis were diagnosed in a 15-week-old female Bull Mastiff which presented with clinical signs compatible with chronic renal failure. Ultrasound examination was consistent with renal dysplasia and clinical pathology supported a diagnosis of chronic renal failure and urinary tract infection. Renal histological examination demonstrated inflammation and scarring with concurrent tubular dysplasia and persisting primitive glomeruli, although the presence of chronic inflammation complicated interpretation. It is uncertain whether renal dysplasia was inherited or due to a urinary tract infection acquired in the neonatal period. Renal dysplasia has not previously been reported in the Bull Mastiff breed.     

Emergency Presentations of the Exotic Small Mammalian Herbivore Trauma Patient

Trauma is a common complaint by owners of small exotic mammalian herbivores (e.g., rabbits, rodents) presented to veterinary hospitals. The term “trauma” is a broad disease category applied to patients with physical debilitation associated with injury often classified as “blunt,” “penetrating,” or “burn” in origin. Because many small exotic mammalian herbivores are prey animals, clinical signs of trauma may be masked until the effects of the injury outweigh the innate nature to survive. Small exotic mammalian herbivores are disproportionately sensitive to stress; thus, pain management and supportive care are extremely important during the initial stages of trauma management. Small exotic mammals differ slightly from other companion animals (e.g., dogs, cats) in regard to common trauma presentations. However, with a few therapeutic modifications (e.g., antibiotic selection, avoidance of corticosteroids, preventing self-trauma), treatment of small exotic mammalian herbivore trauma cases follows the same conventional guidelines used for other companion animals.     

CROSSED RENAL ECTOPIA WITH FUSION IN A CAT

In humans, crossed renal ectopia is a rare, usually asymptomatic, congenital malpositioning of the kidneys, involving wandering of one or both embryonic kidneys across the midline and usually fusion with its contralateral partner. This is the first report of crossed renal ectopia in the cat. A 7-year-old, neutered male cat was presented with polyuria, polydipsia, and a palpable abdominal mass. Diagnostic investigations, including clinical pathology, survey and contrast radiography, and ultrasonography, confirmed the presence of an ectopic left kidney fused with an orthotopic right kidney, with concurrent renal failure and hypertension. Many features of crossed renal ectopia in this cat are similar to those described in humans, however the vascular supply, the presence of renal failure, and the axial rotation of the fused kidney are atypical.     

Clinical and epidemiological features of canine leptospirosis in North Queensland

OBJECTIVE: To evaluate the clinical signs, results of clinical pathology and serology tests, and treatment outcome of clinical leptospirosis in 40 dogs from North Queensland. DESIGN: Retrospective study from January 1995 to August 1999. PROCEDURE: Case records were reviewed for age, breed, sex, month of submission, geographical location and presenting clinical signs in 40 dogs with titres of > or = 200 for leptospirosis by the microscopic agglutination test. A biochemistry panel and complete blood count were performed on 18 dogs. RESULTS: Canine leptospirosis occurred most frequently during the summer and autumn particularly in the 'wet' tropical coastal areas of Mackay and Cairns. Fewer cases were seen in the Atherton Tablelands and 'dry' tropics around Townsville. Young and male dogs were more commonly affected. Most cases were caused by L australis (80%) and L zanoni (15%) with individual cases of L hardjo and L copenhageni. All dogs showed a distinctive multiorgan disease pattern including renal failure and cholestatic hepatopathy. Presenting clinical signs were related to these disease syndromes and included jaundice, vomiting, lethargy, inappetence, dehydration, pyrexia, abdominal pain and diarrhoea. Just over 50% of the dogs in the present study failed to recover. Clinical biochemical changes indicative of renal failure and cholestasis were significantly less severe in dogs that recovered compared with dogs that did not survive. CONCLUSIONS: Clinical pathology testing should be performed on all dogs presented for illness in the endemic areas so as to help make a presumptive diagnosis and assist in determining the prognosis as soon as possible. The presumptive diagnosis should be confirmed serologically.     

Critical Care of the Exotic Companion Mammal (With a Focus on Herbivorous Species): The First Twenty-Four Hours

The number of pet herbivorous exotic mammals is increasing, and their owners are demanding quality medical care. Successful treatment of the critical herbivorous exotic mammal patient is complicated by small patient size, physiological diversity, and a lack of research and clinical data regarding therapeutic response to disease conditions. Despite these impediments, the same principles and techniques used in other domestic animals, such as dogs and cats, can be applied to the herbivorous exotic mammal patient.     

A malignant catarrhal fever-like disease in red deer (Cervus elaphus) in New Zealand

Two case histories are presented to illustrate the clinical and pathological findings of a malignant catarrhal fever-like disease as seen in farmed red deer in New Zealand. Attention is drawn to the similarities with some exotic diseases and the suggestion is made that deer may act as a reservoir for the aetiological agent.     

A malignant catarrhal fever-like disease in red deer (Cervus elaphus) in New Zealand

Two case histories are presented to illustrate the clinical and pathological findings of a malignant catarrhal fever-like disease as seen in farmed red deer in New Zealand. Attention is drawn to the similarities with some exotic diseases and the suggestion is made that deer may act as a reservoir for the aetiological agent.     

Biology and pathology of interactions between fungi and invertebrates.

Having started this review with Di Bassi's work on a fungus destroying the French silkworm industry 160 years ago, the article finishes with a fungus being rendered more pathogenic through genetic engineering to kill an invertebrate. Yet, even while using a fungus as a biological weapon, one needs to be careful not to gun down innocent civilian targets alongside the enemy! It may be argued that this article will have little or no immediate clinical significance for the veterinarian involved in exotic species. And yet it is hoped that it will have provided an interesting and informative (not to say exotic!) introduction to the important area of mycotic disease in exotic species.     

Dietary management of chronic renal disease in dogs: A critical appraisal

Diets low in protein have been recommended for dogs with chronic renal failure (CRF) since 1948, and for apparently healthy old dogs since 1960. These recommendations were based on studies of rats and poorly documented clinical experiences with dogs. Since 1979, a series of eight experiments on partially nephrectomised dogs and four clinical trials on naturally occurring chronic renal disease have demonstrated serious disadvantages of diets that contained high (38 to 49 per cent on a metabolisable energy (ME) basis) or very low (3 to 10 per cent) protein. In addition to poor acceptance of low protein (12 and 16 per cent) diets, undesired responses included exacerbation of depressed renal functions, reduced renal reserve, severe hyperfiltration in single nephrons, metabolic acidosis, hypercholesterolaemia, and hypertension. Protein deficiency may not have caused the complications observed, and may have been due to another feature of the diets fed. In seven studies, diets with a moderate (20 to 31 per cent ME) protein level fared better in regard to reduced renal pathology and proteinuria, better renal functions and reserve, and improvement of clinical status, azotaemia, hyperphosphataemia and anaemia. In the first instance, preferred products for CRF should contain moderate (20 to 24 per cent) protein and minimal phosphorus. Taking into consideration these 12 kidney studies a protein content of 30 per cent is recommended for apparently healthy old dogs. Current recommendations are to introduce a diet that is low in protein at a ‘critical point’ in the course of CRF, when its advantages are likely to outweigh its possible disadvantages. When this critical point has been reached has not been determined, but it is likely to be based on an assessment of the individual case.     

The pathology of acute Nolletia gariepina poisoning of cattle

Toxicity in cattle by the shrub Nolletia gariepina was induced experimentally by intraruminal administration of 3 g/kg dried, milled plant material as a single dose. The animals had to be starved for 24 hours before dosing, as dosing on a full rumen did not induce any signs of toxicity during 5 days of observation and clinical pathology monitoring. Clinical signs were not specific and varied according to the duration (acute versus subacute) of the toxicological process. Clinical pathological parameters indicated renal and to a lesser extent hepatic damage, with raised serum concentrations of urea, creatinine, aspartate aminotransferase (AST) and gamma glutamyl transferase (GGT). Increased urinary sodium and potassium concentration and GGT activity, as well as proteinuria, were evident. Histological and electron microscopic examinations revealed acute renal tubular epithelial cell degeneration and necrosis, especially of the proximal convoluted tubules. Mild hepatocellular degeneration was also noticeable.     

Travel medicine of parasitic diseases in the dog

Companion animals are increasingly brought along by their owners to foreign countries. Thus, small animal travel medicine is becoming more important. The field includes both prophylaxis and metaphylaxis against various infectious diseases, as well as their diagnosis and treatment. Dogs returning from Southern Europe, but also from more tropical regions, may be infected with exotic pathogens. In addition, imported pedigree or working dogs, and especially stray dogs imported through welfare organisations, are at high risk.The present overview summarises the clinical and practical aspects of exotic parasitic diseases that may affect such dogs, and the risk of such diseases becoming autochthonously transmitted in Switzerland. Furthermore, the zoonotic potential of these infections will be considered.     

Ultrasonographic quantitative evaluation of acute and chronic renal disease using the renal cortical thickness to aorta ratio in dogs

The renal cortical thickness (RCT) has been correlated with renal function. Previous studies have also reported that the RCT:Abdominal aorta(Ao) ratio is constant in normal dogs with various physical factors. This multi-center, retrospective, analytical study aimed to determine if there are differences between actual RCT and predicted value of RCT considering physical factors in dogs with acute or chronic renal disease. We also aimed to demonstrate whether the RCT and Ao ratio index would be useful for evaluating renal pathology. A total of 54 dogs with acute or chronic renal disease and 30 normal healthy dogs were included in this study. The RCT was measured at the center of the renal pyramid as the shortest distance perpendicular to the renal capsule from the base of the renal medullary pyramid at three points. The diameter of the Ao was measured just caudal to the branch of the left renal artery in the sagittal plane in systole. The RCT:Ao ratio of chronic kidney disease (CKD) patients was 0.50 ± 0.11 (mean ± standard deviation). The RCT:Ao ratio in normal dogs was 0.67 ± 0.07. The RCT:Ao ratio in patients with acute kidney injury (AKI) was 0.83 ± 0.05. There was a statistically significant difference between normal dogs and dogs with CKD (P < 0.001) and between normal dogs and dogs with AKI (P < 0.001). In conclusion, findings from the current study supported using the RCT:Ao ratio as a non-invasive quantitative method for characterizing kidney pathology in dogs with acute or chronic renal disease.     

Transfusion medicine in exotic pets

The decision to transfuse a patient should always be based on the packed cell volume and clinical status of the patient. This article discusses indications for transfusion and blood substitutes in exotic animal patients. The administration of blood products requires careful donor selection, knowledge of blood groups, cross-matching, and use of anticoagulants. Collection sites, volume, and administration techniques are given for different species of animals including birds, rabbits, and ferrets. Blood-transfusion therapy is not without risk. The frequency with which transfusion reactions occur in exotic pets is unknown. The most common transfusion reactions seen in small animals, along with suggested treatment, are discussed. The availability of blood products is limited in exotic pet medicine; therefore, the use of blood substitutes (Oxyglobin) has the advantage of long storage potential, no need for cross-matching, and no potential for disease transmission. General principles of blood substitutes and administration techniques will be discussed.     

Renal pathology in working dogs in the South African National Defence Force

Urine analysis, serum biochemical profile and a cortical wedge biopsy for histopathological examination was performed on 42 South African National Defence Force (SANDF) dogs from around the country. The only significant finding on urine analysis and serum biochemistry was a relatively large number (16/42) of dogs with elevated serum inorganic phosphate levels. Histopathology revealed that only 9 of the animals had normal kidneys reflected in the wedge biopsy material, with over 50% of them showing signs of glomerular pathology (primarily mesangioproliferative glomerulonephritis). Other conditions detected histopathologically were haemosiderosis (47% of animals), focal nephrosis (2.4%), membranoproliferative glomerulonephritis (2.4%), focal interstitial nephritis (4.7%) and acute tubular nephrosis (4.7%). The lesions observed were of limited distribution and extent; this histopathological finding may account for the absence of significant abnormalities on urine analysis or serum biochemistry profiles. It appears from these results that a large percentage of the SANDF population would be expected to have mild renal lesions, but that these lesions are not severe enough to lead to clinical signs. The findings of this study are similar to those of randomly selected populations of non-military dogs performed in other areas of the world, which also demonstrated an unexpectedly high incidence of histopathological renal pathology in dogs considered healthy. These lesions may well, however, play a role in later life, and it is recommended that military veterinarians maintain an index of suspicion for renal disease, particularly glomerular disease. The aetiology of the histopathological lesions is unknown.