Cataract surgery with foldable intraocular lens implants in captive lowland gorillas (Gorilla gorilla gorilla).

Two juvenile, male, captive-born lowland gorillas (Gorilla gorilla gorilla) with the same father but different mothers developed bilateral cataracts. The cataracts were surgically removed within 6 yr and 3 mo, respectively, of diagnosis, and foldable intraocular lenses were implanted. Although vision was not restored in one eye with a mature, 6-yr-old cataract in gorilla A, surgical intervention on the other eye was performed before a complete cataract developed, and vision was fully restored. Gorilla B was treated at the age of 17 mo, and normal visual development proceeded in both eyes. This animal developed bilateral after-cataract and therefore needed a second intervention in both eyes using Nd:YAG laser treatment. The genetic component of juvenile cataracts should be considered in breeding management programs.     

Ophthalmic examination of the captive western lowland gorilla (Gorilla gorilla gorilla).

This study examined the captive western lowland gorilla (Gorilla gorilla gorilla) eye as compared and contrasted with the human eye. Bilateral ophthalmic examinations of western lowland gorillas (n = 5) while under general anesthesia were performed opportunistically, including slit-lamp biomicroscopy, dilated fundus examination, cycloplegic retinoscopy, Schiotz tonometry, corneal diameter and thickness measurements, A-scan and B-scan ultrasonography, keratometry, and cultures of the eyelid margins and bulbar conjunctiva. Mean spherical equivalent refractive error by cycloplegic retinoscopy was +1.20 +/- 0.59 diopters. Mean intraocular pressure by Schiotz tonometry was 12.0 +/- 4.3 mm Hg. Mean optic nerve head cup to disc ratio was 0.42 +/- 0.11. Mean horizontal corneal diameter was 13.4 +/- 0.8 mm, and mean vertical cornea diameter was 12.7 +/- 0.8 mm. Mean central corneal thickness by ultrasound pachymetry was 489 +/- 52 microm. Mean axial length of the eye by A-scan was 22.75 +/- 0.71 mm. Mean lens thickness by A-scan was 4.23 +/- 0.34 mm. Mean anterior chamber depth by A-scan was 4.00 +/- 0.26 mm. Mean keratometry reading was 44.38 +/- 1.64 diopters. Eyelid margin and bulbar conjunctival cultures isolated Candida sp. (n = 5), Staphylococcus aureus (n = 4), Staphylococcus epidermidis (n = 3), Staphylococcus saccharolyticus (n = 3), and Micrococcus sp. (n = 3). This study suggests important similarities between western lowland gorilla and human eyes. These similarities may allow diagnostics, techniques, and equipment for human eye surgery, such as those used for cataract extraction and intraocular lens implantation, to be successfully utilized for gorillas.     

Cholesterol values in free-ranging gorillas (Gorilla gorilla gorilla and Gorilla beringei) and Bornean orangutans (Pongo pygmaeus).

Cholesterol concentrations in captive gorillas and orangutans vary widely within species and average approximately 244 mg/dl for gorillas and 169 mg/dl for orangutans as published previously. The International Species Inventory System reports higher concentrations of 275 and 199 mg/dl for gorillas and orangutans, respectively. It is unknown whether these values were typical, influenced by captive management, or both. To answer this question, banked serum samples from free-ranging mountain gorillas (Gorilla beringei), western lowland gorillas (Gorilla gorilla gorilla), and Bornean orangutans (Pongo pygmaeus) were analyzed for total cholesterol, triglyceride, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol concentrations. Mountain gorillas did not differ significantly from free-ranging western lowland gorillas in cholesterol, triglyceride, high-density lipoprotein cholesterol, or low-density lipoprotein cholesterol concentrations, indicating mountain gorilla values could be a model for western lowland gorillas. Captive gorilla total cholesterol and low-density lipoprotein cholesterol concentrations were significantly higher (P < 0.05) than in free-ranging groups. Triglyceride concentrations for captive gorillas were significantly higher (P < 0.05) than the male mountain and western lowland gorillas, but they were not significantly different from the female mountain gorillas. Captive orangutan total cholesterol concentrations were only higher (P < 0.05) than the free-ranging female orangutans, whereas captive orangutan low-density lipoprotein cholesterol concentrations were significantly higher (P < 0.05) than both free-ranging male and female orangutans. Calculated and measured low-density lipoprotein cholesterol concentrations were compared for all free-ranging animals and were significantly different (P < 0.05) for all groups, indicating Friedewald's equation for calculating low-density lipoprotein cholesterol is not appropriate for use with nonfasted apes. The higher total cholesterol and low-density lipoprotein cholesterol concentrations in captive apes may predispose them to cardiovascular disease and might be attributed to diets, limited energy expenditure, and genetics.     

Suspected macular degeneration in a captive western lowland gorilla (gorilla gorilla gorilla)

The case of a 31-year-old captive female Western lowland gorilla (Gorilla gorilla gorilla) with decreased near vision but good distance vision is presented. Examination of the fundus revealed drusen-like bodies in the macula presumably because of an age-related macular degeneration (AMD).     

Resolution of a hyperprolactinemia in a western lowland gorilla (Gorilla gorilla gorilla).

Prolactin-secreting pituitary adenomas are one of the most common causes of infertility in women. Prolactin plays an important role in lactation and is involved in producing some of the normal mammalian breeding and maternal behaviors. Elevated serum prolactin concentrations can adversely affect the reproductive cycle in females by inhibiting the normal lutenizing hormone surge that stimulates ovulation. A 17-year-old western lowland gorilla (Gorilla gorilla gorilla) presented with low fertility and hyperprolactinemia. An MRI confirmed a pituitary mass and treatment was initiated with cabergoline. Following 8 mo of treatment, mass size decreased and serum prolactin was within normal limits. The gorilla began to engage in normal breeding behavior, and within 6 mo of completing treatment, was pregnant. Hyperprolactinemia, secondary to presumed microprolactinoma, may be more common among breeding-age gorillas than is currently diagnosed and in humans is an easily diagnosed and treatable condition.     

Severe idiopathic hypocalcemia in a juvenile western lowland gorilla, Gorilla gorilla gorilla

A 6-mo-old, male western lowland gorilla (Gorilla gorilla gorilla) was evaluated because of tetany of both hands. The gorilla had alternating periods of constipation, diarrhea, and bloating since birth. A diagnosis of idiopathic hypocalcemia was based on severe hypocalcemia, a normal vitamin D level, response to oral calcium and vitamin D therapy, and eventual resolution. Idiopathic hypocalcemia, an uncommon disease in neonatal humans, should be considered in young gorillas with persistent gastrointestinal problems or acute tetany.     

Rectal prolapse in a free-ranging mountain gorilla (Gorilla beringei beringei): clinical presentation and surgical management.

A juvenile female mountain gorilla (Gorilla beringei beringei) of the Mubare tourist group in Bwindi Impenetrable National Park, Uganda, developed a severe, complete rectal prolapse that did not spontaneously resolve. Eight months prior, a juvenile female mountain gorilla of the Mubare group developed a mild, complete rectal prolapse that resolved spontaneously within 24 hr. Field guides reported that spontaneously resolving prolapses had been seen previously in two other juveniles, one of which was from the Mubare group. The tissue became increasingly necrotic and maggot infested over the course of 1 wk. Surgical intervention involved amputation of the affected rectal tissues and suturing the viable portion to the anal sphincter muscle with simple interrupted absorbable sutures. The surgery was performed in the field in accordance with Uganda Wildlife Authority policies. Antibiotics and anthelmintics were administered systemically, and the gorilla returned to the group. The gorilla appeared to recover fully after 3 wk. Histology of the resected rectal tissue confirmed intense inflammation and necrosis with myiasis but did not reveal an underlying etiology.     

Analysis of urine from free-ranging mountain gorillas (Gorilla gorilla beringei) for normal physiologic values.

Voided urine samples were collected from apparently healthy free-living mountain gorillas (Gorilla gorilla beringei) and analyzed for normal physiologic values. Mountain gorillas were found to have a high urinary pH (x = 8.45) and low specific gravity (x = 1.013). Commercial dipsticks appear to be unreliable for the measurement of specific gravity and leukocytes. The establishment of urinary reference intervals should aid in the noninvasive detection of certain diseases in the mountain gorilla and assist with prompt and effective decisions regarding the immobilization and treatment of individual gorillas.     

Retrospective evaluation of measles antibody titers in vaccinated captive gorillas (Gorilla gorilla gorilla).

Retrospective analyses of banked serum samples and medical records from captive western lowland gorillas (Gorilla gorilla gorilla) at Lincoln Park Zoo showed that vaccination of gorillas with a human vaccine induced antibody production. No significant relationship was found between the groups that received one, two, or three vaccinations and the probability of seroconversion. These data also suggested that antibodies in western lowland gorillas persist for at least 11 yr. This information is useful in the assessment of vaccination protocols for captive gorillas and in the implementation of preventive care in wild gorilla populations.     

Scabies in free-ranging mountain gorillas (Gorilla beringei beringei) in Bwindi Impenetrable National Park, Uganda

Between August and December 1996, there was an outbreak of a debilitating skin disease attributed to Sarcoptes scabiei infection in mountain gorillas (Gorilla beningei beringei) in Bwindi Impenetrable National Park in Uganda. All four members of a gorilla group which had been habituated to tourists were clinically affected; the infant male gorilla was most severely affected and died, the juvenile male showed serious manifestations of the disease and the two adult animals showed milder signs. The three older animals recovered after a single intramuscular dose of ivermectin. S scabiei mites were observed on skin scrapings and biopsies taken while the juvenile was immobilised and in postmortem samples taken from the infant. The clinical signs did not recur during the following year, and no other gorilla groups in the park were observed to be clinically affected.     

Management of hepatitis B virus infections in two gibbons and a western lowland gorilla in a zoological collection

Since 1996, three primates newly arrived at London Zoo have been found to be infected with hepatitis B virus. The species involved were white-cheeked gibbons (Hylobates leucogenys leucogenys and Hylobates leucogenys siki) and a western lowland gorilla (Gorilla gorilla gorilla). The protocols for the practical management of these cases, including the immunisation of susceptible non-human primates and the staff with recombinant hepatitis B vaccine are described, and the origin and evolution of hepatitis B infection in primates are discussed.     

Chronic hypertension with subsequent congestive heart failure in a western lowland gorilla (Gorilla gorilla gorilla).

Chronic severe subclinical systemic hypertension was diagnosed in a 28-yr-old male western lowland gorilla (Gorilla gorilla gorilla). Thoracic radiography, electrocardiography, and echocardiography revealed an enlarged heart with a hypertrophied left ventricle, mitral regurgitation, and a persistent left bundle branch block. Enalapril, later combined with nifedipine, was of some value in reducing the hypertension, with partial reversal of cardiac enlargement and resolution of the bundle branch block. Two years after initiation of treatment, the gorilla developed lethargy and dyspnea. The diagnosis of heart failure was confirmed under anesthesia; the gorilla did not recover and was euthanized. Postmortem examination confirmed congestive heart failure with chronic, fibrosing cardiomyopathy similar to that in other gorillas.     

Management of reactive arthritis in a juvenile gorilla (Gorilla gorilla gorilla) with long-term sulfasalazine therapy.

A juvenile western lowland gorilla (Gorilla gorilla gorilla) experienced recurrent fever, lethargy, diarrhea, and/or arthritis starting at age 6 mo. During an episode at age 15 mo, Shigella sp. was isolated from diarrheic feces. At age 41 mo, reactive arthritis was diagnosed. In addition, the gorilla's growth was retarded. All arthritic attacks were managed symptomatically prior to age 4 yr, at which time a severe episode precipitated the implementation of therapy with sulfasalazine, an arthritis suppressive medication. Examination 27 mo later revealed cessation of progressive joint pathology although the animal exhibited decreased range of motion in most joints. The gorilla has been on sulfasalazine therapy for 4 yr without lameness. Growth has resumed, and there has been no radiographic evidence of progressive joint degeneration. Immunogenetic analysis of whole blood obtained at age 68 mo identified the gorilla major histocompatibility class I allele, Gogo-B*0101, which has limited nucleotide sequence similarity to HLA-B27, an allele associated with postinfection reactive arthritis in humans. Sulfasalazine therapy effectively managed reactive arthritis in this gorilla and should be considered for similarly frequently affected animals. Juvenile gorillas, in populations with a history of clinical shigellosis and/or postdiarrhea arthritis, may benefit from prophylactic sulfasalazine therapy after episodes of bacterial enterocolitis. Sulfasalazine therapy should be considered in all gorillas, juvenile and adult, experiencing confirmed Shigella sp.-associated enterocolitis.     

Diagnosis of hypothyroidism in a western lowland gorilla (Gorilla gorilla gorilla) using human thyroid-stimulating hormone assay.

Primary hypothyroidism was diagnosed in a 26-yr-old female western lowland gorilla (Gorilla gorilla gorilla) on the basis of serum levels of thyroxine (T4), free T4, and thyroid-stimulating hormone (TSH) measured by human immunoassays. Compared with clinically normal gorillas, the TSH level (107 mlIU/L) was markedly elevated, and T4 (<14.0 nmol/L) and free T4 (5.0 pmol/L) levels were decreased. Thyroid hypofunction could explain the weight gain, unsettled appetite, anxious behavior, lethargy, and poor intraspecies interactions shown by this gorilla. The antibodies in the commercial immunoassay used in this study apparently cross-reacted with gorilla TSH. Supplementation with levothyroxine sodium was initiated and was followed by a marked decrease in circulating TSH and a noticeable improvement in the animal's physiologic status and activity level.     

Resting heart rate and tympanic temperature in operant conditioned western lowland gorillas (Gorilla gorilla gorilla).

The conscious, resting heart rate and body temperature of healthy western lowland gorillas (Gorilla gorilla gorilla) is not reported in the literature. To obtain this information, two clinically healthy adult male western lowland gorillas in a training program were conditioned to allow auscultation and obtain tympanic temperatures. The mean heart rate was 73.8 +/- 8.96 beats per minute (n = 176), and it was lower than mean heart rate reported in studies on anesthetized gorillas. The mean tympanic temperature was 35.5 +/- 0.7 degrees C (95.9 +/- 1.23 degrees F) (n = 209). The right tympanic temperature (rtt) and left tympanic temperature (ltt) were recorded separately for one gorilla. A small but statistically significant difference was present between the mean rtt of 35.8 +/- 0.7 degrees C (96.5 +/- 1.2 degrees F) (n = 137) and the mean ltt of 35.7 +/- 0.8 degrees C (96.2 +/- 1.3 degrees F) (n = 121).     

Acute lymphocytic leukemia in a six-month-old western lowland gorilla (Gorilla gorilla gorilla).

A 6-mo-old hand-raised male western lowland gorilla (Gorilla gorilla gorilla) was diagnosed with acute lymphocytic leukemia based on complete blood count and bone marrow cytology. Clinical signs of the disease were pyrexia, abdominal distention, splenomegaly, and lethargy. Acute lymphocytic leukemia has rarely been reported in this species, and therapy was based on human oncologic protocols. Remission induction chemotherapy resulted in complete clearing of leukemia cells from the bone marrow. Consolidation and maintenance chemotherapy followed. Therapy was facilitated by the use of an infusion port for i.v. treatments and an indwelling lumbar catheter for intrathecal therapy. Side effects associated with chemotherapy were inappetence, moderate alopecia, pancytopenia resulting in sepsis, and bleeding tendency. In spite of initial success, the leukemia reappeared 120 days into treatment. The gorilla was euthanized 7 days later when respiratory distress developed. Intensive care by the animal staff was a key factor in the treatment of this gorilla.     

Alveolar echinococcosis in the zoological garden Basle

Alveolar echinococcosis (AE) is a rare, but potentially severe zoonotic disease caused by Echinococcus (E.) multilocularis. Recent findings indicated an increasing importance of AE for non-human primates living in regions endemic for E. multilocularis. The death of five cynomolgus monkeys (Macaca fascicularis) and a lowland gorilla (Gorilla g. gorilla) due to AE raised concern about the incidence of this parasite in the Basle Zoo. Consequently, a project was initiated to investigate the prevalence amongst an affected group of cynomolgus monkeys, as well as in foxes and mice. Three out of 46 monkeys were seropositive for E. multilocularis antigen. In two of these monkeys and in another three animals, which were seronegative, structures compatible with metacestodal cysts were observed using ultrasonography. Seven out of 35 free roaming foxes caught at the zoo were positive for an intestinal E. multilocularis copro-antigen ELISA, four of them shed taeniid eggs simultaneously. No lesions compatible with AE were present in 50 necropsied mice from the zoo area. These results indicate that the fox population is a potential source to introduce E. multilocularis and may thus represent a risk for the zoo animals.     

Preliminary evaluation of blood lipid profiles in captive western lowland gorillas (Gorilla gorilla gorilla).

Published serum cholesterol values in captive western lowland gorillas (Gorilla gorilla gorilla) are much higher than human ranges, with a national mean of 7.36 mmol/L (284 mg/dl, n = 863). Complete blood lipid profiles were examined in 15 captive gorillas. High-density lipoprotein (HDL) was found to decrease more rapidly with age than total cholesterol, resulting in an increasing ratio of cholesterol HDL with age. The ratio of apolipoprotein B to apolipoprotein Al also increased with age. Establishment of a database of blood lipid values for captive gorillas with correlative analysis of animals with known atherosclerosis status may help to identify sensitive predictors of coronary heart disease risk.     

Evaluation of a human immunometric assay for the determination of thyroid-stimulating hormone in nonhuman primates.

Sera from nine species of clinically healthy nonhuman primates were assayed for T4 and thyroid-stimulating hormone (TSH) using human immunoassays (a fluorescence polarization immunoassay for T4, a microparticle enzyme immunoassay for TSH). The T4 levels ranged from 20 to 132 nmol/L (x +/- SD = 62.8 +/- 24.7 nmol/L). Levels of TSH were detected only in western lowland gorillas (Gorilla gorilla gorilla) and Sumatran orangutans (Pongo pygmaeus abelii) (range, 0.4-10.8 mIU/L; detectable limit = 0.01 mIU/L). The results suggest that the antibodies used in the commercial TSH immunoassay assessed in this study cross-react with gorilla and orang-utan TSH but not with TSH of primates of the genera Macaca, Papio, Erythrocebus, Ateles, Leontopithecus, and Lemur.     

Chorionic villus sampling for sex determination in a western lowland gorilla (Gorilla gorilla gorilla).

Chorionic villus sampling was undertaken on an anesthetized gorilla (Gorilla gorilla gorilla) to determine the fetal sex in the first trimester of pregnancy. The tissue samples were subject to sex determination by polymerase chain reaction, fluorescent in situ hybridization, and cell culture with cytogenetic analysis. Polymerase chain reaction testing was found to be the most accurate and rapid method of sex determination on this tissue sample.