Use of (18)F-fluorodeoxyglucose positron emission tomography-computed tomography to aid in diagnosing intestinal adenocarcinoma in 2 rhesus macaques (Macaca mulatta)

Two aged female rhesus macaques (Macaca mulatta) presented with weight loss and intermittent inappetence. The signalment and constellation of clinical signs led clinicians to suspect the presence of intestinal adenocarcinoma. Because of each animal's advanced age and inconclusive radiographic findings, a noninvasive diagnostic tool was preferred over exploratory laparotomy to assist in determining a diagnosis. Consequently, 2-[(18)F]fluoro-2-deoxy-d-glucose (FDG) positron emission tomography-CT (FDG-PET-CT) was chosen to aid in confirming a suspicion of gastrointestinal adenocarcinoma in both animals. FDG is a glucose analogue labeled with fluorine-18 and is taken up by highly metabolically active cells, as observed in many cancers. Tomography revealed an annular constriction of the small intestine with focal FDG uptake in one animal, and an FDG avid transmural mass in the ascending colon of the second animal. Necropsy later confirmed both sites to be adenocarcinomas. This report supports the use of FDG-PET-CT as an adjunct to conventional radiography in the diagnosis of intestinal adenocarcinoma in nonhuman primates.

Tracheal stenosis and adenocarcinoma in an olive baboon (Papio cynocephalus anubis)

An adult female baboon (Papio cynocephalus anubis) presented for progressive difficulty in endotracheal intubation. Over a 7-y period prior to presentation, she was anesthetized and intubated 67 times for imaging by using single-photon emission computed tomography or positron emission tomography. Laryngoscopic examination revealed tracheal stenosis. Because of increased anesthetic risk and lack of alternative use, she was euthanized, and partial necropsy focusing on the larynx, trachea, and associated structures was performed. Gross examination revealed rigidity and functional fusion of the proximal 5 or 6 tracheal rings and narrowing of the lumen. Histology revealed ossification of tracheal rings and fibrosis of overlying tissue. In addition, a transmural umbilicated mass was present midway down the cervical trachea on its dorsolateral aspect. Histology of the tracheal mass identified a relatively well-circumscribed transmural adenocarcinoma. The combination of overall histologic pattern, evidence of anaplasia, and results of immunohistochemical staining was consistent with a diagnosis of adenoid cystic carcinoma. Anterior tracheal stenosis is a reported complication of intubation in humans and animals. Primary tracheal neoplasms are rare in domestic and research animals and, to our knowledge, have not previously been reported to occur in nonhuman primates.

Poliomyelitis in MuLV-infected ICR-SCID mice after injection of basement membrane matrix contaminated with lactate dehydrogenase-elevating virus

The arterivirus lactate dehydrogenase-elevating virus (LDV) causes life-long viremia in mice. Although LDV infection generally does not cause disease, infected mice that are homozygous for the Fv1(n) allele are prone to develop poliomyelitis when immunosuppressed, a condition known as age-dependent poliomyelitis. The development of age-dependent poliomyelitis requires coinfection with endogenous murine leukemia virus. Even though LDV is a common contaminant of transplantable tumors, clinical signs of poliomyelitis after inadvertent exposure to LDV have not been described in recent literature. In addition, LDV-induced poliomyelitis has not been reported in SCID or ICR mice. Here we describe the occurrence of poliomyelitis in ICR-SCID mice resulting from injection of LDV-contaminated basement membrane matrix. After exposure to LDV, a subset of mice presented with clinical signs including paresis, which was associated with atrophy of the hindlimb musculature, and tachypnea; in addition, some mice died suddenly with or without premonitory signs. Mice presenting within the first 6 mo after infection had regions of spongiosis, neuronal necrosis and astrocytosis of the ventral spinal cord, and less commonly, brainstem. Axonal degeneration of ventral roots prevailed in more chronically infected mice. LDV was identified by RT-PCR in 12 of 15 mice with typical neuropathology; positive antiLDV immunolabeling was identified in all PCR-positive animals (n = 7) tested. Three of 8 mice with neuropathology but no clinical signs were LDV negative by RT-PCR. RT-PCR yielded murine leukemia virus in spinal cords of all mice tested, regardless of clinical presentation or neuropathology.

Fructosamine reference ranges in rhesus macaques (Macaca mulatta)

Naturally occurring diabetes mellitus (DM) is common in several species of Old and New World nonhuman primates. Fructosamine values provide important information about recent glycemic control and can be useful in the diagnosis and management of DM. However, despite an abundance of reports in the literature describing spontaneous and induced DM in monkeys, few reference ranges are available for fructosamine. Reference ranges have been published for woolly monkeys (Lagothrix lagotricha), cynomolgus macaques (Macaca fascicularis), and stumptail macaques (Macaca arctoides) but currently are not available for rhesus macaques. At our institution, DM is a common diagnosis in aging rhesus macaques. Here we report a reference range for fructosamine in rhesus macaques. The overall range was 157 to 230 μmol/L, with male rhesus and macaques 10 y or older having significantly higher values than do female rhesus and macaques younger than 10 y, respectively. This range provides clinical veterinarians with an additional tool for evaluating glycemic control in rhesus macaques.

Maropitant citrate for treatment of ulcerative dermatitis in mice with a C57BL/6 background

Murine ulcerative dermatitis (UD) is a common progressive condition of mice with a C57BL/6 background. Typically, mice present with scabs and crusts on the skin of the dorsal neck and ears, and are often severely pruritic. Animals tend to scratch the lesions, causing additional trauma to the already ulcerated and inflamed skin. Therapeutic intervention largely has been unsuccessful, in part due to the lack of a known cause for the disease. Though the exact etiology of UD has not been elucidated, substance P (SP) has recently been demonstrated as an important neuropeptide linked to the itch-scratch cycle. SP functions at the tachykinin neurokinin 1 (NK1) receptor. We hypothesized that inhibition of SP binding to the NK1 receptor would decrease the itch sensation, thus decreasing scratching behavior and subsequent skin trauma. The purpose of this study was to evaluate the effectiveness of an NK1 receptor antagonist, maropitant citrate, as a treatment for murine UD. Treatment with 1 mg/kg maropitant citrate significantly reduced the size of UD lesions in mice.

Use of p63, a myoepithelial cell marker, in determining the invasiveness of spontaneous mammary neoplasia in a rhesus macaque (Macaca mulatta)

Here we describe a case of mammary gland ductal carcinoma in an aged rhesus macaque. Tumors were diagnosed based on routine hematoxylin and eosin staining. Invasiveness was further characterized by p63 immunohistochemistry. p63 is a p53 homolog that strongly and specifically stains nuclei of myoepithelial cells in human and canine mammary tissue. Because p63 has an affinity for the nucleus of myoepithelial cells, it is readily visible. Staining of mammary tissue from the monkey for p63 revealed that multiple foci of neoplastic cells had breached the myoepithelial cell layer surrounding ducts, suggesting the potential for local invasion of the tumor. Regional metastasis was confirmed at necropsy. To our knowledge, this is the first documented use of p63 for effectively determining the invasive nature of a mammary tumor in a nonhuman primate and the first use of p63 as an effective means of staining myoepithelial cells in a mammary ductal carcinoma in a nonhuman primate. Because nonhuman primates are important animal models for human diseases, including neoplasia, this method may prove useful for both diagnostic and research purposes.