This review highlights the genotype-phenotype relationship of the genetic immunodeficiency disease leukocyte adhesion deficiency (LAD) in humans, dogs, cattle, and mice, and provides assessment of the opportunities that each animal species provides in the understanding of leukocyte biology and in developing new therapeutic approaches to LAD in humans. This comparison is important since animal models of genetic diseases in humans provide the opportunity to test new therapeutic approaches in an appropriate, disease-specific model. The success of this approach is dependent on the relationship of the phenotype in the animal to the phenotype of the disease in humans.

The carcinogen-resistant inbred rat strain DRH established from closed-colony Donryu rats by use of selective brother-sister mating over 20 generations under continuous feeding of 3′-methyl-4-dimethylaminoazobenzene (3′-Me-DAB) maintains a highly resistant phenotype without carcinogen exposure for many years. We reported that the clonal expansion of preneoplastic glutathione S-transferase-P(GST-P)-positive foci induced by 3′-Me-DAB was less extensive in the liver of DRH rats than in the liver of susceptible strains, such as Donryu and F344, although levels of DNA adducts were comparable among these rats. Comparative studies of the events after initiation indicate that DRH rats are constitutionally less prone to cellular damage caused by continuous administration of 3′-Me-DAB than are parental Donryu rats. Consequently, the reduced growth response of the liver during the promotion stage may contribute to the low susceptibility to development of liver tumors. Genetic analysis of (F344 × DRH)F2 rats identified two quantitative trait loci, Drh1 on chromosome 1 and Drh2 on chromosome 4, which provide resistance to the development of GST-P-positive preneoplastic foci induced by 3′-Me-DAB during the early stage of its administration. The resistance to progression to hepatocellular carcinoma is affected solely by Drh2. These observations indicate that at least two genetic loci are critically involved in the steps leading to chemical hepatocarcinogenesis. The DRH rat is a useful experimental model with which to study genetic susceptibility and resistance to chemically induced liver cancers.

In the process of drug discovery, brain and plasma measurements of new chemical entities in rodents are of interest, particularly when the target receptors are in the brain. Brain-to-plasma ratios (B/P) obtained from a rodent pharmacokinetic assay are useful in helping determine which compounds are brain penetrant. The study reported here was performed to determine whether whole-body saline perfusion for complete blood removal was required to accurately measure brain tissue compound concentrations. Diazepam was used as a positive control since it is highly brain penetrant. Compound A was used as a negative control since it had known poor brain penetration. After intravenous dosing with either diazepam or compound A, rats were anesthetized and blood was collected, then the brain was removed following no perfusion or whole-body perfusion with saline. The analytes described (compound A, diazepam, and the internal standard) were recovered from plasma or brain homogenate by use of protein precipitation, and were subsequently analyzed by use of liquid chromatography/tandem mass spectrometry (LC/MS/MS). The B/P values determined by use of LC-MS were not significantly different in perfused vs. non-perfused rats (P ≥ 0.05). This approach (whole brain collected from non-perfused male rats) is an attractive alternative over brain penetration studies of perfused rats, since it has markedly reduced the technical time and potential for pain and distress required for generating B/P data due to elimination of the requirement for anesthesia and surgical preparation of animals.

The use of individually ventilated caging (IVC) to house mice presents new challenges for effective microbiological monitoring. Methods that exploit the characteristics of IVC have been developed, but to the authors' knowledge, their efficacy has not been systematically investigated. Air exhausted from the IVC rack can be monitored, using sentinels housed in cages that receive rack exhaust air as their supply air, or using filters placed on the exhaust air port. To aid laboratory animal personnel in making informed decisions about effective methods for microbiological monitoring of mice in IVC, the efficacy of air monitoring methods was compared with that of contact and soiled bedding sentinel monitoring. Mice were infected with mouse hepatitis virus (MHV), mouse parvovirus (MPV), murine rotavirus (agent of epizootic diarrhea of mice [EDIM]), Sendai virus (SV), or Helicobacter spp. All agents were detected using contact sentinels. Mouse hepatitis virus was effectively detected in air and soiled bedding sentinels, and SV was detected in air sentinels only. Mouse parvovirus and Helicobacter spp. were transmitted in soiled bedding, but the efficacy of transfer was dependent on the frequency and dilution of soiled bedding transferred. Results were similar when the IVC rack was operated under positive or negative air pressure. Filters were more effective at detecting MHV and SV than they were at detecting MPV. Exposure of sentinels or filters to exhaust air was effective at detecting several infectious agents, and use of these methods could increase the efficacy of microbiological monitoring programs, especially if used with soiled bedding sentinels. In contemporary mouse colonies, a multi-faceted approach to microbiological monitoring is recommended.

Invasive bronchoscopy and bronchoaveolar lavage (BAL) fluid collection represents an important tool in studies of the respiratory system of nonhuman primates. Bronchoscopy and BAL fluid collection was performed on groups of rhesus (Macaca mulatta) and cynomolgus (Macaca fasicularis) macaques and African green monkeys (Chlorocebus aethiops), and the resulting comparative lavage cytologic features are described. Analysis of the BAL fluid did not reveal significant differences among species with respect to total cells recovered or differential cellular composition. This description of the method used to lavage the nonhuman primates and the resulting lung cytologic findings provide important comparative data for three species commonly used in biomedical research.

The study reported here was done to determine the relationship between anesthesia depth and bispectral index (BIS) in stimulated pigs. Isoflurane minimal alveolar concentration (MAC) was determined using the tail-clamp method in 16 Yorkshire/Landrace-cross pigs with mean ± SEM weight of 27.7 ± 1.76 kg. One week later, BIS, ECG, heart rate, arterial blood pressure, esophageal temperature, end-tidal CO₂ tension and isoflurane concentration, arterial pH, PaO₂, PaCO₂, plasma bicarbonate concentration, and base excess were determined at each of five isoflurane MAC-multiples: 0.8, 1.0, 1.3, 1.6, and 2.0. Six treatments were studied: isoflurane; isoflurane and atracurium; isoflurane, atracurium, and fentanyl; isoflurane with noxious stimulation; isoflurane and atracurium with noxious stimulation; and isoflurane, atracurium, and fentanyl with noxious stimulation. The noxious stimulus during BIS measurement was the same as that for MAC determination. Each pig was studied three times (n = 8), and order of MAC-multiples and treatments was randomized. Data were evaluated by use of general linear model analysis of variance and linear regression analysis, with statistical significance set at P < 0.05. Significant differences in BIS values were identified between MAC-multiples within each treatment and between treatment 3 compared with treatments 2 and 4. Significant differences also were observed within and between treatments for heart rate, arterial blood pressure, and PaO₂. Use of BIS appears reliable for identification of light versus deep anesthesia, but is of limited use for discrimination between isoflurane MAC-multiples of 1 and 1.6. We conclude that, compared with other treatments, atracurium and noxious stimulation had no significant effect on BIS.

Mycoplasma haemocanis (formerly Haemobartonella canis) is a red blood cell parasite that causes disease mainly in immunosuppressed and splenectomized dogs. Clinical outbreak of the disease resulted in failure of a large experimental project. We aimed to identify whether M. haemocanis has increased prevalence in kennel-raised dogs. In a prospective study, we compared the prevalence of M. haemocanis in whole blood (anti-coagulated by use of EDTA) collected from pet dogs (University of Illinois, Urbana Champaign, Ill.; n = 60) with that in blood from dogs raised in three distinct kennels in western Europe (WE; n = 23), eastern Europe (EE; n = 20), and North America (NA; n = 20). Screening included antibody testing and microscopy of blood smears. The presence of M. haemocanis was identified using a polymerase chain reaction (PCR) assay for specific DNA of the organism. None of the pet dogs (0%) was test positive for M. haemocanis DNA. Mycoplasma haemocanis was found in dogs tested at all of the kennels. Infection rate in the three kennels was 30, 35, and 87%, respectively (all P < 0.001 versus control, χ²-test). Latent infection with M. haemocanis was not a single observation in kennel-raised dogs. Prevalence may be higher than that in a pet dog population. The potential exists for these latent infections to adversely affect or confound research results.

Reovirus infections are typically subclinical in weaned mice, and are best detected using serologic tests. After exposure to the soiled bedding of some mice obtained from various sources, numerous sentinel mice tested reovirus seropositive by use of indirect immunofluorescence assays (IIFA) in our institution. A major commercial rodent pathogen testing laboratory verified our IIFA results, but since the same samples were reovirus seronegative using their “more specific” enzyme-linked immunosorbent assay (ELISA), the IIFA results were reported as “false positives.” As past in-house observations suggested transmission of the virus to sentinel and other animals, we sought to determine whether the IIFA results were always “false positives.” An opportunity to test this notion arose after receipt of reovirus IIFA-positive transgenic mice from an academic source. Using reverse transcriptase-polymerase chain reaction (RT-PCR) assays, the presence of reovirus RNA was detected in fecal specimens taken from some sentinel animals that subsequently seroconverted from IIFA-negative to IIFA-positive for reovirus. The virus could not be isolated by use of tissue culturing methods. Nucleotide sequence analysis established the presence of unique reovirus sequences. These results indicate that contemporary reovirus infections may not be detected by use of some serologic tests, and that RT-PCR analysis may be useful for confirmation of active reovirus infection in certain situations.

Decreased fertility was observed in a breeding colony of C57BL/6J mice. On examination, a dorsoventral vaginal septum was detected in many females. This defect was identified in 1976, with incidence of 4.0% in this strain. Our objective was to determine whether incidence of this condition has increased and whether this defect was associated with the observed infertility. We report incidence of 11.3%, nearly triple the original reported incidence. For comparison, incidence of vaginal septum in C57BL/6N females was determined and was found to be 1%. We performed a breeding study using normal and affected C57BL/6J females to evaluate fertility in affected females. Our data were consistent with those of the 1976 report; fertility was decreased in females with an intact vaginal septum. In 50% of affected females, the septum remained intact after breeding. The fertility for this subgroup of vaginal septum-retained females was 14.3%, compared with 85.7% in females whose septum ruptured and 75.0% in normal females (statistically significant, P = 0.02). On the basis of our results, we provide animal and financial loss data due to the defect. Lastly, we provide suggestions on how to minimize animal losses and be in accordance with the principles of the 3Rs (replacement, refinement, reduction).

A male pig-tailed macaque (Macaca nemestrina), approximately 5 years old, was found to be vision-impaired and to have profound behavioral abnormalities, including hyperactivity and self-injurious behavior that was not amenable to amelioration by environmental enrichment. Facial and skeletal dysmorphisms also were noted. Magnetic resonance imaging (MRI) and positron emission tomography (PET) scanning revealed areas of possible infarction in the occipital lobes and megaventriculosis. At necropsy, following euthanasia for humane reasons, severe polio- and leukoencephalomalacia accompanied by megaventriculosis were seen in both occipital lobes and in several sulci of the parietal and frontal lobes. Light microscopic findings included loss of neocortical structure, with necrosis, neuronal loss, astrogliosis, vascular proliferation, mild spongiosis, and demyelination. The extent and severity of lesions were most pronounced in the occipital lobes and were greater in the left than in the right hemisphere. Other lesions included mild bilateral atrophy of the optic nerves, thymic involution, necrotizing dermatitis due to trauma, and a spectrum of spermatozoal abnormalities. The imaging and gross and light microscopic changes found in this animal resemble the mitochondrial encephalopathies of humans; this was corroborated by results of immunohistochemical analysis demonstrating decreased expression of enzymes of the mitochondrial oxidative complex ([OC]-I, -III, and -IV) in brain and muscle, and detection of fibrinogen immunoreactivity in neurons and glial cells. The spermatozoal defects may represent yet another aspect of a mitochondrial defect.

An outbreak of combined Sarcoptes and Malassezia spp. infection was diagnosed in a rabbitry. About 20 (4%) of 500 rabbits were affected. Two 6- to 8-month-old female Holland Lops rabbits were submitted to the Tifton Diagnostic & Investigational Laboratory at The University of Georgia for complete necropsy. Gross lesions consisted of marked multifocal areas of alopecia, crusting, and dermatitis around the eye and on ears, nose, lips, neck, abdomen, feet, and external genitalia. Histologic examination of the skin revealed epidermal acanthosis with marked parakeratotic hyperkeratosis and cross sections of embedded mites consistent with Sarcoptes sp. and budding yeasts consistent with Malassezia sp. To the best of the author's knowledge, this is the first case report of combined Sarcoptes and Malassezia spp. infection in rabbits.

Ampullary carcinoma was diagnosed in 6 rhesus macaques that ranged in age from 20 to 35 years. Signalment, premonitory signs of disease, and results of clinical biochemical and hematologic analyses varied among animals. Histologically, the neoplastic cells obliterated the ampulla, with regional spread to the duodenum in all 6 animals and to the pancreas in one animal. Two animals had metastases to the lung, and another two had metastases to the pancreoduodenal lymph nodes and liver. One animal had mesocolonic metastasis. Malignant tumors of the ampullary region are rare in domestic animals, and account for less than 5% of all cancers of the digestive tract in humans.

An 18-year-old rhesus macaque (Macaca mulatta) developed ptosis of the left upper eyelid due to a mass that had first been observed 10 years previously. The 11 × 7 × 7-mm mass was surgically excised, and the ptosis resolved after 5 days. Histologic examination of the mass revealed two confluent cell populations. Most cells were spindle-shaped and were arranged in loose fascicles. Smaller numbers of cells had squamous differentiation. The spindle-shaped cells expressed smooth muscle actin. Cells with squamous differentiation did not express smooth muscle actin, but did, along with around half of the spindle-shaped cells, express pan-cytokeratin. On the basis of histologic and immunohistochemical findings, the mass was diagnosed as myoepithelioma. The neoplasm most likely originated from the palpebral lobe of the lacrimal gland, although accessory lacrimal gland origin could not be excluded. Recurrence of the neoplasm has not been observed 6 months after surgery.