Acute Phase Protein Levels in Rabbits with Suspected Encephalitozoon cuniculi Infection

Branching Out: Rabbit Models Provide Evidence for the Use of a Willow Cultivar (Salix miyabeana) as a Suitable Forage Material for Monogastric Herbivores in Zoos

We assessed the suitability of a willow cultivar for monogastric herbivores in zoos using a rabbit model. Thirty-six male New Zealand White × Californian rabbits at 5 weeks of age were provided with bark and leaf material from a willow cultivar, Salix miyabeana (SX61), in one of four treatments for 6 weeks: UC (unrestricted control of pelleted diet); RC (restricted control of pelleted diet); TL (restricted pellets + fresh willow leaf material); and TB (restricted pellets + fresh willow bark material). Daily feed intake and weekly weights were recorded. Fasted blood samples were taken between 8:00 and 11:00 h, and blood biochemistry and acute phase protein (APP) were quantified at the start and end of the study. After the 6-week study period, rabbits were euthanized, and liver and kidney weights were obtained to assess hepatocellular damage. Blood biochemistry results were mainly within reference ranges and suggest a lack of toxicity or cellular damage due to feeding different amounts of willow ingredients. Greater weight gain was observed in the UC group when compared to the RC (p < 0.01), TB, and TL (p < 0.05) groups at the end of the treatment period. Total dry matter (DM) intake was greater in both TB and TL treatment groups when compared to the RC group but lower than the UC group (p < 0.05) across the treatment period. At the end of the study, phosphorus, magnesium, glucose, and AST were lower in the RC group when compared to all other treatment groups (p < 0.05) with a greater blood urea nitrogen than the TL and TB groups (p < 0.01). The TL group had greater blood potassium concentrations and a lower Na:K ratio than the UC and TB groups (p < 0.01). No differences were observed in the APP response over time and among groups; only fibrinogen was greater in the RC compared to the TB group (p < 0.05). The relative liver weight was higher in the UC group when compared to TB (p < 0.05). Given these results, willow bark and leaves at a high dietary inclusion can be considered safe and effective forage materials for monogastric herbivores in zoos.

Encephalitozoon cuniculi Infection of Domestic Rabbits (Oryctolagus cuniculus) in Slovenia between 2017 and 2021

Encephalitozoon cuniculi is a microsporidial parasite that primarily infects domestic rabbits (Oryctolagus cuniculus). It is the causative agent of encephalitozoonosis, a disease with an internationally recognized seroprevalence among rabbits. This study determines the presence, clinical manifestation, and serological status of encephalitozoonosis in pet rabbits in Slovenia using various diagnostic procedures. From 2017 to 2021, 224 pet rabbit sera were collected and tested for encephalitozoonosis with the indirect immunofluorescence assay. Immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies against E. cuniculi were confirmed in 160 (65.6%) cases. Most seropositive rabbits suffered from neurological clinical signs or signs of gastrointestinal disorders such as recurrent hypomotilities, chronic weight loss, cachexia, or anorexia, and fewer showed clinical signs related to the urinary system or phacoclastic uveitis. A quarter of the positively tested rabbits presented without clinical signs. Hematological and biochemical blood analysis confirmed that seropositive animals had elevated globulin and deviated albumin levels in comparison to the normal reference values of non-infected animals. Furthermore, rabbits with neurological clinical signs showed statistically significant higher levels of globulins and total protein. Sixty-eight whole-body radiographs and thirty-two abdominal ultrasound reports were analyzed, looking for changes in the shape or size of the urinary bladder, presence of urinary sludge or uroliths, and any abnormalities related to the kidneys (shape, size, or nephrolites). The results suggest that neurological defects in the urinary bladder caused by E. cuniculi lead to a distended urinary bladder and consequently dysuria, incontinence, urine scalding, and sludgy urine.

Protein electrophoresis of non-traditional species: A review

EPH has been demonstrated to be a useful tool in companion animals while providing an opportunity to characterize globulinemias, including paraproteinemia. In EPH of non-traditional species, these same applications are important, but the primary use is to gauge the acute-phase and humoral immune responses. This includes the valid quantitation of albumin as well as the examination of fractions reflective of increases in acute-phase reactants and immunoglobulins. Agarose gel EPH and, more recently, capillary zone EPH have been applied to samples from these species. Performing these analyses provides special challenges in the placement of fraction delimits, generation of RIs, and interpretation of results. Recommended as part of routine bloodwork, EPH can also provide key results that are helpful in clinical and field-based health assessments as well as in prognostication.

Serum Health Biomarkers in African and Asian Elephants: Value Ranges and Clinical Values Indicative of the Immune Response

Simple Summary

Biomarkers are biological molecules found in the blood or other fluids or tissues that can indicate normal or abnormal processes or disease. Developing tools to measure biomarkers that indicate immune function and establishing concentrations observed within a species is an important first step in their use for managing health and understanding disease processes. Here we report assays, observed value ranges, and concentrations during illness or injury for seven immune biomarkers measured in the serum of African and Asian elephants under human care. Concentrations were variable in both clinical and non-clinical samples, but all seven biomarkers were elevated in at least one case and most increased in response to routine vaccination in a single Asian elephant. These tools provide an exciting avenue for monitoring health status and helping diagnose and treat health problems in wildlife species, like elephants.

Abstract

Serum biomarkers indicative of inflammation and disease can provide useful information regarding host immune processes, responses to treatment and prognosis. The aims of this study were to assess the use of commercially available anti-equine reagents for the quantification of cytokines (tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ), interleukins (IL) 2, 6, and 10) in African (Loxodonta africana, n = 125) and Asian (Elephas maximus, n = 104) elephants, and alongside previously validated anti-human reagents for acute-phase proteins (serum amyloid A and haptoglobin), calculate species-specific biomarker value ranges. In addition, we used opportunistically collected samples to investigate the concentrations of each biomarker during identified clinical cases of illness or injury, as a first step to understanding what biomarkers may be useful to managing elephant health. Immune biomarkers were each elevated above the calculated species-specific value ranges in at least one clinical case, but due to variability in both clinical and non-clinical samples, only serum amyloid A was significantly higher in clinical compared to non-clinical paired samples, with tendencies for higher TNF-α and IL-10. We also detected increased secretion of serum amyloid A and all five cytokines following routine vaccination of a single Asian elephant, indicating that these biomarkers can be beneficial for studying normal immune processes as well as pathology. This study indicates that assays developed with commercial reagents can be used to quantify health biomarkers in wildlife species and identifies several that warrant further investigation to elucidate immune responses to various pathologies.

ESTABLISHMENT OF ACUTE-PHASE PROTEIN AND SERUM PROTEIN ELECTROPHORESIS PRELIMINARY REFERENCE VALUES FOR PRONGHORN (ANTILOCAPRA AMERICANA)

Pronghorn (Antilocapra americana) are native to western North America and are found in 24 Association of Zoos and Aquariums (AZA)-accredited institutions. Acute-phase proteins (APP) are a broad class of proteins that are stimulated in response to inflammation and have been shown to be a sensitive measure of inflammation in equids and ruminants. In this study, blood samples from clinically normal free-ranging and captive populations of pronghorn were analyzed using assays for protein electrophoresis (EPH) and APP, including serum amyloid A (SAA) and haptoglobin (HP), to develop preliminary ranges to gauge potential differences between these populations. Additional samples were taken from clinically abnormal captive pronghorn with facial abscesses. By EPH measurements, albumin: globulin ratio mean and SE were significantly different (P <0.05) with 1.02 (0.08) for captive populations and 1.91 (0.05) for free-ranging populations. Total protein mean and SE were significantly different (P <0.05) for captive and free-ranging populations, respectively 5.6 (0.3) g/dl and 6.9 (0.1) g/dl. Mean and SD of SAA for captive pronghorn were 1.4 (3.2) mg/L, and were significantly different from the free-ranging population, which was below the limits of detection for (P <0.05). There was no difference in HP levels between these groups. In a case study of a pronghorn with facial abscesses, elevated levels of HP, but not SAA, suggested that HP maybe useful in certain disease states. Future studies should explore the use of these biomarkers as tools to monitor general health, prognosis, and subclinical disease.

ACUTE-PHASE RESPONSES IN HEALTHY, MALNOURISHED, AND OTOSTRONGYLUS-INFECTED JUVENILE NORTHERN ELEPHANT SEALS (MIROUNGA ANGUSTIROSTRIS)

Acute-phase proteins (APPs) are utilized to detect early inflammation in many domestic and nondomestic species, but variability exists between species and inflammatory diseases as to which APPs are most useful. Stranded juvenile northern elephant seals (NESs; Mirounga angustirostris) undergoing rehabilitation at the Marine Mammal Center experience high mortality rates due to severe arteritis caused by the lungworm, Otostrongylus circumlitis (OC), and there are currently no effective antemortem diagnostic tools for this disease. To characterize patterns of the acute-phase response in the NES, two APPs-serum amyloid A (SAA) and C-reactive protein (CRP)-were measured, and serum protein electrophoresis was performed to measure albumin and globulin fractions in 81 serum samples from 58 NESs in four different health states: healthy, malnourished, preclinical for OC infection, or clinical for OC infection. Compared to healthy NESs (median, 11.2 mg/L), SAA concentrations were significantly increased in malnourished (33.9 mg/L), preclinical (247 mg/L), and clinical OC-infected NESs (328 mg/L) (P < 0.05). CRP concentrations were increased only in clinical OC-infected NESs (median, 53.9 mg/L) and were below detectable limits in the other three groups (<0.01 mg/L). These results show that SAA and CRP are positive APPs in NESs with OC infection, and that SAA may serve as the major APP for this species. Albumin : globulin ratios were significantly increased in malnourished NESs (median, 1.26) and decreased in clinical OC-infected NESs (0.53). As a result, albumin is a negative APP in the NES, similar to other mammalian species. APP monitoring can be helpful in detecting and monitoring inflammation in rehabilitating juvenile NESs.

Clinical Signs, Diagnosis, and Treatment of Encephalitozoon cuniculi Infection in Rabbits

Central vestibular dysfunction caused by Encephalitozoon cuniculi frequently mimics the condition of a peripheral disorder. A negative antibody titer rules out E cuniculi as the cause of present clinical signs. Cerebrospinal fluid analysis including polymerase chain reaction is considered an inappropriate diagnostic method for in vivo diagnosis of encephalitozoonosis. The usefulness of glucocorticoid anti-inflammatories in the treatment of encephalitozoonosis is called into question. Encouraging activity early in the course of disease and adding in therapeutic exercise may represent the most important part of therapy in rabbits with vestibular dysfunction associated with encephalitozoonosis.

Evidence-Based Advances in Rabbit Medicine

Rabbit medicine has been continuously evolving over time with increasing popularity and demand. Tremendous advances have been made in rabbit medicine over the past 5 years, including the use of imaging tools for otitis and dental disease management, the development of laboratory testing for encephalitozoonosis, or determination of prognosis in rabbits. Recent pharmacokinetic studies have been published, providing additional information on commonly used antibiotics and motility-enhancer drugs, as well as benzimidazole toxicosis. This article presents a review of evidence-based advances for liver lobe torsions, thymoma, and dental disease in rabbits and controversial and new future promising areas in rabbit medicine.

Microsporidiosis in Vertebrate Companion Exotic Animals

Veterinarians caring for companion animals may encounter microsporidia in various host species, and diagnosis and treatment of these fungal organisms can be particularly challenging. Fourteen microsporidial species have been reported to infect humans and some of them are zoonotic; however, to date, direct zoonotic transmission is difficult to document versus transit through the digestive tract. In this context, summarizing information available about microsporidiosis of companion exotic animals is relevant due to the proximity of these animals to their owners. Diagnostic modalities and therapeutic challenges are reviewed by taxa. Further studies are needed to better assess risks associated with animal microsporidia for immunosuppressed owners and to improve detection and treatment of infected companion animals.