Natural pathology of the Baboon (Papio spp.)

Background Baboons are useful animal models for biomedical research, but the natural pathology of the baboon is not as well defined as other non‐human primates. Methods A computer search for all morphologic diagnoses from baboon necropsies at the Southwest National Primate Research Center was performed and included all the natural deaths and animals euthanized for natural causes. Results A total of 10,883 macroscopic or microscopic morphologic diagnoses in 4297 baboons were documented and are presented by total incidence, relative incidence by sex and age‐group, and mean age of occurrence. The most common diagnoses in descending order of occurrence were hemorrhage, stillborn, amyloidosis, colitis, spondylosis, and pneumonia. The systems with the most diagnoses were the digestive, urogenital, musculoskeletal, and respiratory. Conclusion This extensive evaluation of the natural pathology of the baboon should be an invaluable biomedical research resource.     

Pathology of the male baboon (Papio spp.) urogenital system

Background Comprehensive reports on male baboon urogenital pathology are not available. Methods We performed a retrospective study of 2246 male baboon necropsy records over 19 years. Results A total of 289 urogenital lesions were diagnosed in 197 (8.8%) baboons. The most frequently affected organs in decreasing order were kidney, testicle, urinary bladder, penis and prepuce, seminal vesicle, ureter, and prostate. Lesions were rare in the urethra, scrotum, and epididymis. The most common diagnoses in decreasing order were nephritis, urinary bladder cystitis, nephrocalcinosis, pyelonephritis, renal cysts, renal amyloidosis, testicular atrophy, penile/preputial dermatitis, hydronephrosis, orchitis/testicular abscess, glomerulonephritis, renal hemorrhage, hypospadia, nephrosis, renal infarct, hypospermia/aspermia, seminal vesicle mineralization, and hydroureter. We also report six cases of hypospadia, the first report in the baboon. Conclusions The male baboon has a low incidence of urogenital disease and renal disease is the most common malady. The role of herpesvirus papio 2 needs further study.     

Spontaneous gallbladder pathology in baboons

Background Gallbladder pathology (GBP) is a relatively uncommon, naturally occurring morbidity in both baboons and humans. Methods A retrospective analysis was performed on 7776 necropsy reports over a 20 year period to determine the prevalence of baboon GBP. Results Ninety‐seven cases of GBP were identified, yielding a 20 year population prevalence of 1.25%. GBP is more common in adult female baboons, occurring with a female to male ratio of nearly 2:1. Among gallbladder pathologies, cholecystitis (35.1%) and cholelithiasis (29.9%) were the most prevalent abnormalities, followed by hyperplasia (16.5%), edema (15.5%), amyloidosis (5.2%), fibrosis (4.1%), necrosis (4.1%), and hemorrhage (1.0%). Conclusion Many epidemiologic similarities exist between GBP in baboons and humans suggesting that the baboon may serve as a reliable animal model system for investigating GBP in humans.     

Group Composition of Guinea Baboons (<Emphasis Type="Italic">Papio papio</Emphasis>) at a Water Place Suggests a Fluid Social Organization

Baboon social systems are among the most studied in primates. Solid knowledge of the hamadryas and savannah baboon systems has accumulated, leading to a dichotomic view of baboon social systems. Hamadryas baboons live in multilayered troops based on 1-male units whereas savannah baboons live in multimale multifemale groups based on a network of related females. Less attention has been paid to their West African congenerics, the Guinea baboons, Papio papio. To fill this gap, in 2007 we initiated a long-term study of a baboon troop ranging in the Niokolo Koba National Park in southeastern Senegal. Earlier studies suggested a tendency for a multilayered social system in Guinea baboons, similar to the hamadryas baboon organization. Therefore, as a first approach to analyzing variability in party size and composition, we observed members of the troop crossing an open area from a fixed point for 3 mo during the dry and wet seasons. We counted individuals and recorded changes in composition of both arriving and departing parties. Party size and composition were highly variable on both a daily and a seasonal basis; 45.9% of the arriving parties changed in composition while crossing the open area, either splitting into smaller parties or fusing into larger ones, suggesting a fluid organization. Our data support the existence of neither a hamadryas baboon-like multilayered social organization nor a stable medium-sized multimale multifemale group as in savannah baboons. In light of our data we may need to revise the dichotomic view of baboon social systems and include space for greater variability of their social systems.     

Record review of baboons with histologically confirmed endometriosis in a large established colony

Spontaneous endometriosis was diagnosed in 43 baboons over a 14-year period. Thirty-seven have died; five remain alive; one was sold and lost to follow-up. The average age at diagnosis was 17.2 years; 29 (67%) were between 12 and 21 years of age. Fifteen (35%) were diagnosed by biopsy and received surgical excision of the endometriotic tissue; four of these were identified during caesarian section, confirming one prior report of endometriosis in pregnant animals. Twenty-eight (65%) were diagnosed at or shortly preceding necropsy. When diagnosed by a palpable abdominal mass, there was a significantly greater likelihood the animal died or was killed as a result of complications of endometriosis. When diagnosis was at necropsy, there was a significantly greater likelihood that the animal died from causes unrelated to endometriosis. Early identification with surgical removal appears to provide a benefit for both survival and delivering offspring after diagnosis. In twenty-one baboons (49%), endometriosis affected multiple sites within the peritoneal cavity. In the remaining baboons, lesions were more localized. Ovarian involvement was seen in sixteen (37%) of these baboons. This paper is the first to describe significant ovarian involvement in baboons, previously considered a limitation of the usefulness of this species as an animal model. We also describe the first reported endometriosis seeding of an abdominal surgery scar in a baboon. Many of these baboons were middle aged, had few or no offspring, or had evidence of a long duration of uninterrupted menstrual cycles, consistent with risk factors for women. Endometriosis was an incidental finding in 17 (40%) of these baboons, consistent with previous reports of minimal endometriosis as a common asymptomatic finding in baboons and in women. Overall, endometriosis in baboons presents a spontaneously occurring animal model that shares important features with the disease in women and the rhesus macaque.     

The baboon model (Papio hamadryas) of fetal loss: maternal weight,age, reproductive history and pregnancy outcome

Background Several risk factors are associated with the incidence of human stillbirths. The prevention of stillbirths in women is a pressing clinical problem. Methods We reviewed 402 pathology records of fetal loss occurring in a large baboon (Papio spp.) colony during a 15‐year period. Clinical histories of 565 female baboons with one or more fetal losses during a 20‐year period were analyzed for weight, age, and reproductive history. Results Fetal loss was most common at term (35.57%) and preterm (28.61%) and less common in the first half of gestation (11.20%) and post‐term (5.22%). Greater maternal weight, older age, history of stillbirth and higher parity were independent predictors for stillbirth. An exponential increase in the incidence of fetal loss was observed beginning at age 14 years in baboons. Conclusions Fetal loss and maternal risk factors associated with stillbirths in baboons were similar to those documented in women.     

Progressions of adult male chacma baboons (Papio ursinus) in the moremi wildlife reserve

It has been suggested that the sociospatial organization of baboon progressions has a protective function in which the most physically powerful troop members, the adult males, play a key role. This theory implies regularities in adult male progression order for different species of savannah baboons with similar social systems. Quantitative progression data are available from two such similar baboon species, olive and yellow, but not from the third, chacma. The order of movement of 15 adult male chacma baboons was determined from 40 progressions observed at the Moremi Wildlife Reserve, Botswana. The chacma males were most often found in the front sixth of progressions, next most often in the second sixth, and about equally often from there to the rear. As expected from the protection theory, this frontal positioning is consistent with available quantitative data from other species of savannah baboons.     

Trichobezoars in baboons

Background  There is little information available concerning trichobezoars in the non-human primate literature.
Methods  We evaluated 118 cases of trichobezoar in baboons over a 29-year period at the Southwest National Primate Research Center.
Results  The anatomic locations affected in decreasing order were the stomach, small intestine, cecum, esophagus and colon. The most common clinical history was weight loss. The most frequent associated pathology included gastrointestinal inflammation and ulceration, emaciation, peritonitis, intussusception, pneumonia, and aspiration. Trichobezoars were the cause of death in nine baboons and the reason for euthanasia in 12. Females were 2.14 times more likely than males to be affected. The greater the percentage of group housing time, the more likely the baboon is to develop trichobezoars.
Conclusions  The baboon may present a useful model to evaluate the etiology, genetic predisposition, physiopathology, neurobiology, and treatment response of trichobezoars.     

Myxomatous neoplasms in the perineal region of baboons

Background In baboons, Papio sp. neoplasms tend to affect the hematopoietic system most commonly, with rare documentation of myxomatous neoplasms. In contrast, women can develop myxomatous masses within deep peripelvic tissues with some frequency during their reproductive years. Methods We have identified and examined, retrospectively, myxomatous perineal masses in twelve female baboons within one research facility and compared their histopathologic, immunohistochemical and electron microscopic features to their human variants. Results Our results indicate that these myxomatous neoplasms, in humans and non‐human primates, share common features. Conclusion Further research, particularly molecular genetic analysis, may be needed to identify the baboon as a true animal model for myxomatous perineal neoplasms.     

Natural pathology of the captive chimpanzee (Pan troglodytes): A 35‐year review

We present the spontaneous pathological lesions identified as a result of necropsy or biopsy for 245 chimpanzees (Pan troglodytes) over a 35‐year period. A review of the pathology database was performed for all diagnoses on chimpanzees from 1980 to 2014. All morphologic diagnoses, associated system, organ, etiology, and demographic information were reviewed and analyzed. Cardiomyopathy was the most frequent lesion observed followed by hemosiderosis, hyperplasia, nematodiasis, edema, and hemorrhage. The most frequently affected systems were the gastrointestinal, cardiovascular, urogenital, respiratory, and lymphatic/hematopoietic systems. The most common etiology was undetermined, followed by degenerative, physiologic, neoplastic, parasitic, and bacterial. Perinatal and infant animals were mostly affected by physiologic etiologies and chimpanzee‐induced trauma. Bacterial and physiologic etiologies were more common in juvenile animals. Degenerative and physiologic (and neoplastic in geriatric animals) etiologies predominated in adult, middle aged, and geriatric chimpanzees.     

Spontaneous pathology of the baboon endocrine system

Background  Study of endocrine pathology in animal models is critical to understanding endocrine pathology in humans.
Methods  We evaluated 434 endocrine-related diagnoses from 4619 baboon necropsies, established the incidence of spontaneous endocrine pathology, and analyzed the clinical and biochemical data associated with the individual cases.
Results  The most common diagnoses in descending order, were pancreatic islet cell amyloidosis (n = 259), ovarian cysts (n = 50), pituitary adenoma (n = 37), pancreatic islet cell adenoma (n = 20), granulosa cell tumor (n = 15), thyroid adenoma (n = 11), adrenal hyperplasia (n = 10), thyroid carcinoma (n = 8), and pheochromocytoma (n = 6). The incidence of pancreatic islet cell amyloidosis progressively increased with age. Pheochromocytomas were associated with renal and heart failure. The incidence of pancreatic islet cell amyloidosis and adrenal pathology was similar to humans; the incidence of pituitary adenoma and thyroid pathology was lower than in humans.
Conclusions  Endocrine disease in baboons is common and shares clinical and biochemical characteristics with endocrine disease in humans.     

An encephalomyocarditis virus epizootic in a baboon colony.

Approximately 80 baboon deaths were caused by encephalomyocarditis virus (EMCV) infection in a 3060 member research and production colony. The epizootic extended over a 9-month period and occurred in baboons ranging from 1 day to 22 years of age. Acute death was the most common history. When clinical disease was detected, it was characterized by labored respiration associated with acute congestive heart failure. The salient necropsy findings were pulmonary congestion and edema, hydropericardium, hydrothorax, ascites, lymph node and splenic hypertrophy, and pale white-to-tan mottled hearts. The most significant histologic lesion was nonsuppurative necrotizing myocarditis. Placental infection with fetal loss occurred. Diagnosis was confirmed by light microscopy, transmission electron microscopy, virus culture, and serology. Rarely, EMCV-induced antibody persisted in surviving baboons for more than 24 months. EMCV-infected feral rats were the probable source of the virus and their control stopped the epizootic. No EMCV neutralizing antibody was detected in colony support personnel or chimpanzees.     

Hand-rearing baboons for laboratory investigations

To conduct laboratory studies in unsedated animals that were similar anatomically and physiologically to man, five full term baboons (four Papio cynocephalus anubis, one Papio cynocephalus cynocephalus) were hand-reared. These infants were used as unsedated animal models in short-term lung clearance studies conducted from birth to 2 years of age. The hand-rearing techniques described here encouraged the formation of an infant-human rearer bond that permitted us to control the level of expressed aggressive behavior as the infant matured. These techniques resulted in baboons which displayed subordinate behavior, showed positive reception to human contact (without evidence of negative stereotypic behavioral anomalies) and remained cooperative subjects for our investigations of short-term pulmonary clearance. The baboons generally were above average in weight in comparison to conspecifically-reared baboons of similar age, sex and species. Representative lung retention curves presented on one baboon demonstrate the feasibility of lung clearance studies in these hand-reared animals. Due to its suitability for unsedated studies, this baboon model may be considered for other types of laboratory investigations.     

The baboon gene for apolipoprotein A-I: characterization of a cDNA clone and identification of DNA polymorphisms for genetic studies of cholesterol metabolism

We have isolated and sequenced a baboon apolipoprotein A-I (ApoA-I) clone from a liver cDNA library using a human cDNA hybridization probe. This baboon cDNA contains the entire ApoA-I coding region (801 bp, 267 aa), a 3' untranslated region, and a poly(A)tail. Among comparisons with apoAI sequences from other species, the baboon cDNA is most similar to that of the cynomolgus macaque (99.2% homologous) and least similar to the rat sequence (72.6% homologous). A high frequency of nonsynonymous substitutions are observed by alignment of baboon and human apoAI cDNAs, but comparisons of hydrophilicity profiles show that protein structure is conserved by substitutions of aa with similar properties. A polymorphic PstI cleavage site was identified by Southern blot analysis and subsequently mapped to the 5' end of the baboon apoAI gene. To identify effects of apoAI allelic variation on cholesterol metabolism, we used immunoblotting to compare the distributions of ApoA-I among lipoprotein size classes in baboons from each genotype under basal and atherogenic diets. We observed an increase of ApoA-I in high density lipoprotein (size class 1) particles after atherogenic diets in homozygotes for one allele, as compared to slight decreases in the other genotypes.     

Natural Chagas disease in four baboons

Background  Chagas disease is common in Central and South America and the southern United States. The causative agent is Trypanosoma cruzi (order Kinetoplastida, family Trypanosomatidae), a kinetoplastid protozoan parasite of humans and other vertebrates. It is a serious public health issue and the leading cause of heart disease and cardiovascular death in Central and South America. In 1984, a colony baboon was discovered to be infected with T. cruzi .
Methods  As the initial diagnosis was made by microscopic observation of the amastigote forms of T. cruzi in myocardial fibers, T. cruzi amastigotes have been identified in three additional baboons.
Results  The primary findings were similar in all four baboons and were congestive heart failure with edema of dependent areas, hydrothorax, hydropericardium, and multifocal to diffuse lymphoplasmacytic myocarditis.
Conclusions  A baboon animal model of Chagas disease could contribute significantly to the development of therapies for the disease in humans.     

Human–hamadryas baboon (Papio hamadryas) conflict in the Wonchit Valley,South Wollo,Ethiopia

Understanding the extent of human–primate conflict is crucial to the development of conservation and management strategies. We carried out this study in an unprotected area of central Ethiopia to examine the magnitude of human–hamadryas baboon (Papio hamadryas) conflict and to assess the attitude of local farmers towards baboons in Wonchit Valley. In 2014, we interviewed 119 adult respondents using a structured questionnaire. Local farmers considered hamadryas baboons to be the major pest in the area. All respondents reported that hamadryas baboons caused crop raiding and small livestock predation in the region. Respondents reported that a shortage of fruit producing wild trees and ready availability of crops were the main causes of conflict between farmers and hamadryas baboons. We found that hamadryas baboons damaged cereal crops at dusk and dawn during full moonlight, and most (89.9%) respondents claimed that they were not interested in hamadryas baboon conservation. Our results indicate that human–hamadryas baboon conflict has a strongly negative impact on both baboon conservation and local farmers. We suggest that to mitigate the human–hamadryas baboon conflict, job opportunities such as beekeeping should be introduced in the region.     

Diet‐induced early‐stage atherosclerosis in baboons: Lipoproteins,atherogenesis, and arterial compliance

Background

The purpose of this study was to determine whether dietary manipulation can reliably induce early‐stage atherosclerosis and clinically relevant changes in vascular function in an established, well‐characterized non‐human primate model.

Methods

We fed 112 baboons a high‐cholesterol, high‐fat challenge diet for two years. We assayed circulating biomarkers of cardiovascular disease (CVD) risk, at 0, 7, and 104 weeks into the challenge; assessed arterial compliance noninvasively at 104 weeks; and measured atherosclerotic lesions in three major arteries at necropsy.

Results

We observed evidence of atherosclerosis in all but one baboon fed the two‐year challenge diet. CVD risk biomarkers, the prevalence, size, and complexity of arterial lesions, plus consequent arterial stiffness, were increased in comparison with dietary control animals.

Conclusions

Feeding baboons a high‐cholesterol, high‐fat diet for two years reliably induces atherosclerosis, with risk factor profiles, arterial lesions, and changes in vascular function also seen in humans.     

Dental eruption schedules of wild and captive baboons

Dental eruption schedules previously used to age wild baboons have in the past derived from studies of captive animals housed under standard conditions and fed standard laboratory diets. This paper reports for the first time eruption schedules derived from wild baboons, the yellow baboons (Papio hamadryas cynocephalus) of Mikumi National Park, Tanzania, and compares these schedules with those of other baboon subspecies inhabiting both similar and dissimilar environments. Eighteen males and twelve females from the Viramba groups, ranging in age from 21 to 103 months, were trapped, and dental impressions and notes were made of the state of eruption of each tooth. Eruption of all teeth were delayed at Mikumi relative to the baboon standards derived from the captive animals at the Southwest Foundation for Biomedical Research, San Antonio, Texas. Teeth of the canine-premolar 3 complex and third molars were most delayed, erupting up to a year and a half later than their counterparts from captive animals. Comparison with data on hamadryas baboons from Erer-Gota in Ethiopia revealed that both the hamadryas and yellow subspecies of baboons, with different genetic backgrounds and living under markedly different environmental conditions, followed the same schedule. This constancy of developmental schedules suggests that these Mikumi data may reasonably be used as standards for other wild baboon populations and that acceleration of dental maturation, as well us maturation of other somatic systems in captivity, is another manifestation of the short-term adaptive plasticity of the baboon species as a whole.     

Differences between the normal vaginal bacterial community of baboons and that of humans

Humans and baboons (Papio spp.) share considerable anatomical and physiological similarities in their reproductive tracts. Given the similarities, it is reasonable to expect that the normal vaginal microbial composition (microbiota) of baboons would be similar to that of humans. We have used a 16S rRNA phylogenetic approach to assess the composition of the baboon vaginal microbiota in a set of nine animals from a captive facility and six from the wild. Results show that although Gram‐positive bacteria dominate in baboons as they do in humans, there are major differences between the vaginal microbiota of baboons and that of humans. In contrast to humans, the species of Gram‐positive bacteria (Firmicutes) were taxa other than Lactobacillus species. In addition, some groups of Gram‐negative bacteria that are not normally abundant in humans were found in the baboon samples. A further level of difference was also seen even within the same bacterial phylogenetic group, as baboon strains tended to be more phylogenetically distinct from human strains than human strains were with each other. Finally, results of our analysis suggests that co‐evolution of microbes and their hosts cannot account for the major differences between the microbiota of baboons and that of humans because divergences between the major bacterial genera were too ancient to have occurred since primates evolved. Instead, the primate vaginal tracts appear to have acquired discrete subsets of bacteria from the vast diversity of bacteria available in the environment and established a community responsive to and compatible with host species physiology. Am. J. Primatol. 73:119–126, 2011. © 2010 Wiley‐Liss, Inc.