Comparative Pathology of Aging Great Apes: Bonobos, Chimpanzees, Gorillas, and Orangutans.

The great apes (chimpanzees, bonobos, gorillas, and orangutans) are our closest relatives. Despite the many similarities, there are significant differences in aging among apes, including the human ape. Common to all are dental attrition, periodontitis, tooth loss, osteopenia, and arthritis, although gout is uniquely human and spondyloarthropathy is more prevalent in apes than humans. Humans are more prone to frailty, sarcopenia, osteoporosis, longevity past reproductive senescence, loss of brain volume, and Alzheimer dementia. Cerebral vascular disease occurs in both humans and apes. Cardiovascular disease mortality increases in aging humans and apes, but coronary atherosclerosis is the most significant type in humans. In captive apes, idiopathic myocardial fibrosis and cardiomyopathy predominate, with arteriosclerosis of intramural coronary arteries. Similar cardiac lesions are occasionally seen in wild apes. Vascular changes in heart and kidneys and aortic dissections in gorillas and bonobos suggest that hypertension may be involved in pathogenesis. Chronic kidney disease is common in elderly humans and some aging apes and is linked with cardiovascular disease in orangutans. Neoplasms common to aging humans and apes include uterine leiomyomas in chimpanzees, but other tumors of elderly humans, such as breast, prostate, lung, and colorectal cancers, are uncommon in apes. Among the apes, chimpanzees have been best studied in laboratory settings, and more comparative research is needed into the pathology of geriatric zoo-housed and wild apes. Increasing longevity of humans and apes makes understanding aging processes and diseases imperative for optimizing quality of life in all the ape species.

Pulmonary tuberculosis in Asian elephants (Elephas maximus): histologic lesions with correlation to local immune responses.

Although Mycobacterium tuberculosis infection is an important health concern for Asian elephants (Elephas maximus), no studies have evaluated the associated local immune responses or histologic lesions. In primates including humans, latent tuberculosis is distinguished by well-organized granulomas with TH1 cytokine expression, whereas active disease is characterized by poorly organized inflammation and local imbalance in TH1/TH2 cytokines. This study examined archival, formalin-fixed, paraffin-embedded lung samples from 5 tuberculosis-negative and 9 tuberculosis-positive Asian elephants. Lesions were assessed by light microscopy, and lymphoid infiltrates were characterized by CD3 and CD20 immunolabeling. Expression of TH1 (interferon [IFN]-γ, tumor necrosis factor [TNF]-α) and TH2 (interleukin [IL]-4, IL-10, transforming growth factor [TGF]-ß) cytokines was determined using in situ hybridization. In 6 of 9 samples, inflammation was similar to the pattern of primate active disease with low to moderate numbers of lymphocytes, most of which were CD20 positive. In 1 sample, inflammation was most similar to latent tuberculosis in primates with numerous CD3-positive lymphocytes. Expression of IFN-γ was detected in 3 of 8 tuberculosis-positive samples. Expression of TNF-α was detected in 3 of 8 positive samples, including the one with latent morphology. Low-level expression of IL-4 was present in 4 of 8 positive samples. Only single positive samples displayed expression of IL-10 and TGF-ß. Tuberculosis-negative samples generally lacked cytokine expression. Results showed heterogeneity in lesions of elephant tuberculosis similar to those of latent and active disease in primates, with variable expression of both TH1 and TH2 cytokines.

Cerebral and Ocular Ochroconiasis in 2 Elegant Crested Tinamou (Eudromia elegans) Chicks.

Two elegant crested tinamou chicks (Eudromia elegans), aged 27 and 50 days, respectively, died following acute onset of weakness and neurologic disease. Microscopically, the cerebral hemispheres of both chicks and the optic lobes of 1 chick contained multifocal granulomatous and heterophilic inflammation and necrosis with intralesional pigmented, thin-walled, fungal hyphae. In 1 chick, hyphae extended along the optic nerve into the globe and were associated with severe granulomatous and heterophilic inflammation of the choroid, retina, pecten, and vitreous. In both chicks, polymerase chain reaction amplification of the fungal 28S large subunit ribosomal RNA was positive with 99% sequence identity to Ochroconis gallopava. While a well-characterized fungal infection of domestic poultry, ochroconiasis has rarely been reported in exotic avian species, and this is the first histologic characterization of ocular ochroconiasis in any avian species.

Leukoencephalomyelopathy of mature captive cheetahs and other large felids: a novel neurodegenerative disease that came and went?

A novel leukoencephalomyelopathy was identified in 73 mature male and female large captive felids between 1994 and 2005. While the majority of identified cases occurred in cheetahs (Acinonyx jubatus), the disease was also found in members of 2 other subfamilies of Felidae: 1 generic tiger (Panthera tigris) and 2 Florida panthers (Puma concolor coryi). The median age at time of death was 12 years, and all but 1 cheetah were housed in the United States. Characteristic clinical history included progressive loss of vision leading to blindness, disorientation, and/or difficulty eating. Neurologic deficits progressed at a variable rate over days to years. Mild to severe bilateral degenerative lesions were present in the cerebral white matter and variably and to a lesser degree in the white matter of the brain stem and spinal cord. Astrocytosis and swelling of myelin sheaths progressed to total white matter degeneration and cavitation. Large, bizarre reactive astrocytes are a consistent histopathologic feature of this condition. The cause of the severe white matter degeneration in these captive felids remains unknown; the lesions were not typical of any known neurotoxicoses, direct effects of or reactions to infectious diseases, or nutritional deficiencies. Leukoencephalomyelopathy was identified in 70 cheetahs, 1 tiger, and 2 panthers over an 11-year period, and to our knowledge, cases have ceased without planned intervention. Given what is known about the epidemiology of the disease and morphology of the lesions, an environmental or husbandry-associated source of neurotoxicity is suspected.

Occlusive fungal tracheitis in 4 captive bottlenose dolphins (Tursiops truncatus).

Respiratory disease is common in dolphins, primarily affecting pulmonary parenchyma and sparing large airways. Over a 10-year period, 4 captive adult bottlenose dolphins succumbed to chronic, progressive respiratory disease with atypical recurrent upper respiratory signs. All dolphins had severe, segmental to circumferential fibrosing tracheitis that decreased luminal diameter. Histologically, tracheal cartilage, submucosa, and mucosa were distorted and replaced by extensive fibrosis and pyogranulomatous inflammation centered on fungal hyphae. In 3 of 4 cases, hyphae were morphologically compatible with Aspergillus spp and confirmed by culture in 2 cases. Amplification of fungal DNA from tracheal tissue was successful in one case, and sequences had approximately 98% homology to Aspergillus fumigatus. The remaining case had fungi compatible with zygomycetes; however, culture and polymerase chain reaction were unsuccessful. Lesions were evaluated immunohistochemically using antibodies specific to Aspergillus spp. Aspergillus-like hyphae labeled positively, while presumed zygomycetes did not. These cases represent a novel manifestation of respiratory mycoses in bottlenose dolphins.

Meeting report: Emerging respiratory viral infections and nonhuman primate case reports.

A workshop on Emerging Respiratory Viral Infections and Spontaneous Diseases in nonhuman primates was sponsored by the concurrent Annual Meetings of the American College of Veterinary Pathologists and the American Society for Veterinary Clinical Pathology, held December 1-5, 2012, in Seattle, Washington. The session had platform presentations from Drs Karen Terio, Thijs Kuiken, Guy Boivin, and Robert Palermo that focused on naturally occurring influenza, human respiratory syncytial virus, and metapneumovirus in wild and zoo-housed great apes; the molecular biology and pathology of these viral respiratory diseases in nonhuman primate (NHP) models; and the therapeutic and vaccine approaches to prevention and control of these emerging respiratory viral infections. These formal presentations were followed by presentations of 14 unique case studies of rare or newly observed spontaneous lesions in NHPs (see online files for access to digital whole-slide images corresponding to each case report at http://scanscope.com/ACVP%20Slide%20Seminars/2012/Primate%20Pathology/view.apml). The session was attended by meeting participants that included students, pathology trainees, and experienced pathologists from academia and industry with an interest in respiratory and spontaneous diseases of NHPs.

Characterization of the gastric immune response in cheetahs (Acinonyx jubatus) with Helicobacter-associated gastritis.

Captive cheetahs have an unusually severe progressive gastritis that is not present in wild cheetahs infected with the same strains of Helicobacter. This gastritis, when severe, has florid lymphocyte and plasma cell infiltrates in the epithelium and lamina propria with gland destruction, parietal cell loss, and, in some cases, lymphoid follicles. The local gastric immune response was characterized by immunohistochemistry in 21 cheetahs with varying degrees of gastritis. The character of the response was similar among types of gastritis except that cheetahs with severe gastritis had increased numbers (up to 70%) of lamina proprial CD79a+CD21- B cells. CD3+CD4+ T cells were present in the lamina propria, and CD3+CD8α+ T cells were within the glandular epithelium. Lymphoid aggregates had follicular differentiation with a central core of CD79a+/CD45R+ B cells and with an outer zone of CD3+ T cells that expressed both CD4 and CD8 antigens. MHC II antigens were diffusely expressed throughout the glandular and superficial epithelium. No cheetah had evidence of autoantibodies against the gastric mucosa when gastric samples from 30 cheetahs with different degrees of gastritis were incubated with autologous and heterologous serum. These findings indicate that T-cell distribution in cheetahs is qualitatively similar to that in other species infected with Helicobacter but that large numbers of lamina propria activated B cells and plasma cells did distinguish cheetahs with severe gastritis. Further research is needed to determine whether alterations in the Th1:Th2 balance are the cause of this more plasmacytic response in some cheetahs.

Meeting report: Spontaneous lesions and diseases in wild, captive-bred, and zoo-housed nonhuman primates and in nonhuman primate species used in drug safety studies.

The combination of loss of habitat, human population encroachment, and increased demand of select nonhuman primates for biomedical research has significantly affected populations. There remains a need for knowledge and expertise in understanding background findings as related to the age, source, strain, and disease status of nonhuman primates. In particular, for safety/biomedical studies, a broader understanding and documentation of lesions would help clarify background from drug-related findings. A workshop and a minisymposium on spontaneous lesions and diseases in nonhuman primates were sponsored by the concurrent Annual Meetings of the American College of Veterinary Pathologists and the American Society for Veterinary Clinical Pathology held December 3-4, 2011, in Nashville, Tennessee. The first session had presentations from Drs Lowenstine and Montali, pathologists with extensive experience in wild and zoo populations of nonhuman primates, which was followed by presentations of 20 unique case reports of rare or newly observed spontaneous lesions in nonhuman primates (see online files for access to digital whole-slide images corresponding to each case report at http://www.scanscope.com/ACVP%20Slide%20Seminars/2011/Primate%20Pathology/view.apml). The minisymposium was composed of 5 nonhuman-primate researchers (Drs Bradley, Cline, Sasseville, Miller, Hutto) who concentrated on background and spontaneous lesions in nonhuman primates used in drug safety studies. Cynomolgus and rhesus macaques were emphasized, with some material presented on common marmosets. Congenital, acquired, inflammatory, and neoplastic changes were highlighed with a focus on clinical, macroscopic, and histopathologic findings that could confound the interpretation of drug safety studies.

Morphologic evidence suggestive of hypertension in western gray kangaroos (Macropus fuliginosus).

Marked renal vascular changes, suggestive of hypertension, were present in adult western gray kangaroos (Macropus fuliginosus) from a single facility over a 14-year period. A subset of these kangaroos also had vague clinical nervous system deficits, including blindness. To characterize the vascular lesions, determine prevalence, and document other changes, case histories and archival tissue sections from 21 adult kangaroos (8 male, 13 female) that died or were euthanatized between 1994 and 2008 were reviewed. Relevant lesions included increased thickness of the renal arteriolar tunica media with smooth muscle hypertrophy and/or hyperplasia, accumulation of extracellular matrix within arterioles, increased vascular tortuosity, and varying degrees of juxtaglomerular hyperplasia. Renal tissue from two more severely affected animals was further examined by transmission electron microscopy, highlighting arteriolar endothelial cell hypertrophy and disruption of the medial architecture. Hypertrophy of arteries and arterioles in other organ systems was also present (3/21), including vessels in the brain and spinal cord of one animal with clinical neurologic signs. Four kangaroos had antemortem retinal detachment, a potential sequel of hypertension in humans and domestic mammals. The cause of these vascular lesions in this mob is uncertain. Lesions were not associated with an infectious disease process, age, underlying renal disease, or thyroid abnormalities. In the absence of other causes, hypertension was a differential. Further investigation into clinical significance and predisposing factors, such as genetics and diet, is warranted.

Fecal cortisol metabolite analysis for noninvasive monitoring of adrenocortical function in the cheetah (Acinonyx jubatus).

A radioimmunoassay was validated for quantifying excreted cortisol metabolites in cheetah (Acinonyx jubatus) feces. High-performance liquid chromatography analysis indicated that immunoreactivity was associated with a water-soluble metabolite in fecal extracts from males and females. None of the immunoreactivity corresponded with free cortisol or corticosterone but rather was associated with a more polar, unidentified metabolite. To determine the biologic relevance of excreted immunoreactive cortisol metabolites, cheetahs were exposed to a variety of situations anticipated to increase cortisol secretion. First, to assess acute changes in adrenal activity, adrenocorticotropic hormone (ACTH; 400 IU i.m.) was administered to two adult males and two adult females. Pre-ACTH baseline serum cortisol and fecal cortisol metabolite concentrations varied among individuals. Serum cortisol concentrations were elevated above baseline within 10 min of ACTH injection, followed by corresponding increases in fecal cortisol metabolite concentrations (690-4,194% above baseline) 48 hr later in three of four cheetahs. In the fourth cheetah, a smaller increase (334% above baseline) in fecal cortisol metabolite excretion was observed 96 hr after ACTH injection. Seven cheetah females also were subjected to a variety of potentially stressful manipulations, including immobilization, translocation, and introduction to a male to assess the ability of this technique to detect physiologic changes in adrenal activity. Increased fecal corticoid metabolite excretion was observed 24-72 hr after exposure to these exogenous stressors. Results indicate that adrenocortical activity can be monitored noninvasively in the cheetah through analysis of these metabolites. This technique could be valuable for evaluating, and thus optimizing, environmental and management conditions and for investigating the role of stress in disease pathogenesis and the usually poor reproductive performance of this species in captivity.

Comparative pathology of nocardiosis in marine mammals.

Nocardia spp. infections in mammals cause pyogranulomatous lesions in a variety of organs, most typically the lung. Members of the Nocardia asteroides complex are the most frequently recognized pathogens. Nine cases of nocardiosis in free-ranging pinnipeds and 10 cases of nocardiosis in cetaceans were evaluated. Host species included the hooded seal (Cystophora cristata, n = 8), leopard seal (Hydrurga leptonyx, n = 1), Atlantic bottlenose dolphin (Tursiops truncatus, n = 4), beluga whale (Delphinapterus leucas, n = 4), and killer whale (Orcinus orca, n = 2). The most common presentation of nocardiosis in both pinnipeds and cetaceans was the systemic form, involving 2 or more organs. Organs most frequently affected were lung and thoracic lymph nodes in 7 of 9 cases in pinnipeds and 8 of 10 cases in cetaceans. Molecular identification and bacterial isolation demonstrated a variety of pathogenic species. N. asteroides, N. farcinica, N. brasiliensis, and N. otitisdiscaviarum are pathogenic for pinnipeds. In cetaceans N. asteroides, N. farcinica, N. brasiliensis, N. cyriacigeorgica, and N. levis are pathogenic. Hematoxylin and eosin and acid fast staining failed to reveal bacteria in every case, whereas modified acid fast and Grocott's methenamine silver consistently demonstrated the characteristic organisms. In both pinnipeds and cetaceans, juvenile animals were affected more often than adults. Hooded seals demonstrated more cases of nocardiosis than other pinnipeds.

Amyloidosis in black-footed cats (Felis nigripes).

A high prevalence of systemic amyloidosis was documented in the black-footed cat (Felis nigripes) based on a retrospective review of necropsy tissues (n = 38) submitted as part of ongoing disease surveillance. Some degree of amyloid deposition was present in 33 of 38 (87%) of the examined cats, and amyloidosis was the most common cause of death (26/38, 68%). Amyloid deposition was most severe in the renal medullary interstitium (30/33, 91%) and glomeruli (21/33, 63%). Other common sites included the splenic follicular germinal centers (26/31, 84%), gastric lamina propria (9/23, 39%), and intestinal lamina propria (3/23, 13%). Amyloid in all sites stained with Congo red, and in 13 of 15 (87%) cats, deposits had strong immunoreactivity for canine AA protein by immunohistochemistry. There was no association with concurrent chronic inflammatory conditions (P = .51), suggesting that amyloidosis was not secondary to inflammation. Adrenal cortical hyperplasia, a morphologic indicator of stress that can predispose to amyloid deposition, was similarly not associated (P = .09) with amyloidosis. However, adrenals were not available from the majority of cats without amyloidosis; therefore, further analysis of this risk factor is warranted. Heritability estimation suggested that amyloidosis might be familial in this species. Additionally, tissues from a single free-ranging black-footed cat had small amounts of amyloid deposition, suggesting that there could be a predilection for amyloidosis in this species. Research to identify the protein sequence of serum amyloid A (SAA) in the black-footed cat is needed to further investigate the possibility of an amyloidogenic SAA in this species.

Transitional cell carcinoma in fishing cats (Prionailurus viverrinus): pathology and expression of cyclooxygenase-1, -2, and p53.

A high prevalence of urinary bladder transitional-cell carcinoma (TCC) has been noted in captive fishing cats (Prionailurus viverrinus). Of the 91 adult deaths between 1995 and 2004, 12 (13%) were attributed to TCC. To help elucidate mechanisms of carcinogenesis, archival sections of urinary bladder from 14 fishing cats were examined histologically and immunohistochemically for p53, cyclooxygenase (COX)-1, and COX-2 expression. Ten cats had TCC, and 4 were unaffected. The average age at death was 10.8 years in affected individuals and 10.5 years in unaffected individuals. There was no sex predilection. Fishing cat TCCs were characterized histologically as papillary and infiltrating (n = 6), nonpapillary and infiltrating (n = 3), or carcinoma in situ (n = 1). Glandular and squamous metaplasia, necrosis, and lymphatic invasion were prominent histologic features. Two individuals had documented metastasis. p53 nuclear immunolabeling was detected in 4/10 (40%) TCCs. In two cases, immunolabeling was limited to less than 10% of the neoplastic cellular population and was comparable to staining of normal fishing cat bladder. Therefore, p53 gene mutation did not appear to be an essential component of TCC carcinogenesis in examined fishing cats. COX-1 immunohistochemistry was negative in all cases. All TCCs had some degree of COX-2 cytoplasmic immunolabeling, which was exclusively within the invasive portions of the neoplasms. Papillary portions were uniformly negative. COX-2 overexpression was a prominent feature in the majority of the examined fishing cat TCCs, suggesting that COX-2-mediated mechanisms of carcinogenesis are important in this species and that COX-inhibiting drugs may be of therapeutic benefit.

Comparison of Helicobacter spp. in Cheetahs (Acinonyx jubatus) with and without gastritis.

Chronic gastritis causes significant morbidity and mortality in captive cheetahs but is rare in wild cheetahs despite colonization by abundant spiral bacteria. This research aimed to identify the Helicobacter species that were associated with gastritis in captive cheetahs but are apparently commensal in wild cheetahs. Helicobacter species were characterized by PCR amplification and sequencing of the 16S rRNA, urease, and cagA genes and by transmission electron microscopy of frozen or formalin-fixed paraffin-embedded gastric samples from 33 cheetahs infected with Helicobacter organisms (10 wild without gastritis and 23 captive with gastritis). Samples were screened for mixed infections by denaturant gel gradient electrophoresis of the 16S rRNA gene and by transmission electron microscopy. There was no association between Helicobacter infection and the presence or severity of gastritis. Eight cheetahs had 16S rRNA sequences that were most similar (98 to 99%) to H. pylori. Twenty-five cheetahs had sequences that were most similar (97 to 99%) to "H. heilmannii" or H. felis. No cheetahs had mixed infections. The ultrastructural morphology of all bacteria was most consistent with "H. heilmannii," even when 16S rRNA sequences were H. pylori-like. The urease gene from H. pylori-like bacteria could not be amplified with primers for either "H. heilmannii" or H. pylori urease, suggesting that this bacteria is neither H. pylori nor "H. heilmannii." The cagA gene was not identified in any case. These findings question a direct role for Helicobacter infection in the pathogenesis of gastritis and support the premise that host factors account for the differences in disease between captive and wild cheetah populations.