Herpesvirus and Subsequent Usutu Virus Infection in a Great Grey Owl (Strix nebulosa) at the Ljubljana Zoo, Slovenia.

Herpesvirus (HV) has been known to cause disease in owls, with various clinical signs and outcomes for the last several decades. The HV DNA polymerase gene was detected in oropharyngeal and cloacal swabs of a male great grey owl (Strix nebulosa) in a zoological collection in Ljubljana, Slovenia. In the following 4 months, despite continuous HV detection in swabs, no clinical signs with a clear link to HV disease were observed. Hepatoprotective and immunostimulant therapies applied during this period did not prevent HV shedding. Therefore, peroral antiviral therapy with acyclovir (150 mg/kg q24 h for seven days) was performed, and the owl tested negative at the next sampling and remained negative for the next 8 months. After that, the owl again tested positive for HV presence, and the same protocol with antiviral therapy was performed. After 3 weeks with a negative test for HV presence, without any clinical signs of illness, the owl suddenly died because of Usutu virus (USUV) infection. Among all the owls at the zoo, interestingly, only the HV-positive great grey owl died because of USUV infection. The USUV sequence detected and obtained in this study clusters together with other Europe 2 sequences detected in neighboring countries. Our study shows the potential of acyclovir therapy in the prevention of herpesvirus shedding and, moreover, lowering the possibility for spreading HV to other owls and birds. To the best of our knowledge, this is the first report of HV presence and USUV infection in a great grey owl in Slovenia.

Amdoparvovirus-associated disease in red pandas (Ailurus fulgens).

The roster of amdoparvoviruses (APVs) in small carnivores is growing rapidly, but in most cases, the consequences of infection are poorly understood. Red panda amdoparvovirus (RPAV) is highly prevalent in zoo-housed red pandas and has been detected in both healthy and sick animals. Clarifying the clinical impact of RPAV in this endangered species is critical, and zoological collections offer a unique opportunity to examine viral disease association in carefully managed populations. We evaluated the potential impact of RPAV in captive red pandas with a combination of prospective and retrospective analyses. First, we collected feces from 2 healthy animals from one collection over a 6-year period and detected virus in 72/75 total samples, suggesting that RPAV can be a long-term subclinical infection. We next investigated the infections using a retrospective study of infection status and tissue distribution in a cohort of necropsied animals. We performed polymerase chain reaction and in situ hybridization on 43 necropsy cases from 4 zoo collections (3 from the United States, 1 from Europe, 1997-2022). RPAV was present in these populations for at least 2 decades before its discovery and is detectable in common and significant lesions of zoo-housed red pandas, including myocarditis (3/3 cases), nephritis (9/10), and interstitial pneumonia (2/4). RPAV is also detectable in sporadic lesions, including multisystemic pyogranulomatous inflammation, oral/pharyngeal mucosal inflammation, and dermatitis. The colocalization of virus with lesions supports a role in causation, suggesting that despite the apparently persistent and subclinical carriage of most infections, RPAV may have a significant impact in zoo collections.

Lingual Ultrastructural and Histochemical Study in the Patagonian Mara (Rodentia: Caviidae, Dolichotis patagonum) in Relation to Other Hystricomorphs.

The study describes the ultrastructure of the tongue in the Patagonian mara (Dolichotis patagonum) using light and scanning electron microscopy. Histochemical methods were used for evaluation of lingual salivary glands. The tongue is divided into a small and rounded apex, a narrow corpus, and a significantly wider radix, with a well-developed lingual prominence. The tip of the apex is free of papillae. The caudal part of the apex and the corpus are covered by filiform papillae. Round fungiform papillae are scattered among them. Papillae on the narrow stalk are conical. The radix contains caudally bent papillae forming wide flat prominences, slender, hook shaped filiform papillae, foliate papillae, and two oval vallate papillae. Taste buds were found on the lateral sides of the foliate and vallate papillae. Purely serous salivary glands are beneath the vallate and foliate papillae. Serous acini and mucous tubules are in the lingual radix. The Patagonian mara is the only hystricomorph rodent with described hyaline cartilage strengthening the lingual radix. Some typical signs of adaptation to herbivorous diet were found. The structure of the tongue is adapted to grass-feeding, as grasses form the main component of their diet.

Prevalence of red panda amdoparvovirus infection in European zoos.

Red panda amdoparvovirus (RPAV) was first described in captive red pandas (Ailurus fulgens) at a zoo in the United States in 2018. Subsequently, the prevalence of infection in zoos in the United States was reported to be 50%; however, RPAV prevalence outside the United States remains unstudied. This study was conducted to investigate the prevalence of RPAV in 134 red pandas from zoos in Europe. Overall, RPAV was detected with PCR in 21 of 62 zoos (33.9%), and the virus prevalence among individuals was estimated to be 24.2% (95% confidence interval, 17.4%-32.0%). Remarkably, adult females tested positive for RPAV more frequently than adult males. Zoos where RPAV was detected reported a significantly higher occurrence of alopecia (and clinical signs in general), whereas other commonly reported problems (fecal disorders and dental disease) showed no difference. A repeated pooled sampling of two positive individuals further showed that RPAV excretion in feces is intermittent, with the viral DNA being only detected on 8 out of 14 sampling days. The intermittent nature of excretion implies that RPAV prevalence may be higher than the estimated value.

Comparison of Cortisol Concentrations in Different Matrices in Alpine Ibex (Capra ibex) at the Zoo.

The usefulness of blood collection using venipuncture versus kissing bugs or medicinal leeches and the collection of saliva, faeces, hair, urine, and tears for measuring "immunoreactive" C (iC) concentration in Alpine ibexes was verified using commercial enzyme immunoassays. The mean value of serum C was highest in serum collected using venipuncture and lowest in serums collected using kissing bugs. Statistically significant differences were observed between venipuncture and kissing bugs and between leeches and kissing bugs. However, no statistically significant difference was found in C concentrations between samples collected with venipuncture and those collected with leeches. The highest mean value of C concentration was measured in serum (all three methods), followed by that in hair and faeces, and the lowest mean value was found in saliva. Statistically significant differences were found between saliva and faeces samples and between saliva and hair samples. The difference between the concentrations for faeces and hair was not statistically significant. A significant difference in C concentration between males and females was found in saliva. A significant difference in C concentration among different ages was measured in serum obtained using venipuncture in all three groups and in faeces between the groups older than ten years and younger than 10 months. Highly significant differences in C concentrations were also found between hair sampled in summer and hair sampled in autumn. Collecting tear and urine samples is a laborious procedure and is therefore less acceptable for C determination. Due to the small number of samples, statistical values are not given for these two matrices.

Fatal cerebrovascular accident in a captive red panda (Ailurus fulgens fulgens) with concurrent amdoparvovirus infection.

We report the pathological and molecular findings in an adult male Himalayan red panda (Ailurus fulgens fulgens) whose death was attributed to parenchymal brain haemorrhage (PBH) of the thalamus. Post-mortem examination revealed severe, acute PBH and intraventricular haemorrhage with major involvement of the thalamus, as well as scattered chronic microinfarctions. Vascular disease in the brain and other organs was suggestive of systemic hypertension. Histological lesions included arteriolar hyalinosis and varying degrees of arteriosclerosis, arterial tunica media hypertrophy and hyperplasia and infiltration of arterial walls by lipid-laden macrophages. Other relevant findings included marked myocardial fibrosis, lymphoplasmacytic tubulointerstitial nephritis, lymphoplasmacytic meningoencephalitis and chronic mitral valve degeneration. The changes in the cerebral vasculature were consistent with hypertensive encephalopathy and a cerebrovascular accident, specifically PBH, which has not been previously reported in this species. Additionally, polymerase chain reaction analysis for red panda amdoparvovirus (RPAV) was positive in the brain and kidneys. Preceded by hypertensive vascular changes and brain microinfarctions, sudden death in this animal likely resulted from fatal PBH with intraventricular haemorrhage. The clinicopathological role of RPAV infection is unknown in this case, although its contribution to the chronic renal disease is considered possible in the context of our current understanding of RPAV-associated pathology.

Comparative Study of Lingual Papillae, Lingual Glands and Lyssa of the Tongue of Selected Wild Felids (Carnivora, Felidae) in Biological Aspects.

Although much attention has been paid in the literature to the morphology of the tongue in various animal species, including some Felidae, it has not yet been described in detail in the vulnerable Neofelis nebulosa and Panthera leo bleyenberghi and the last concern Lynx lynx and Otocolobus manul. Therefore, the present study aimed to characterize the features of the tongue surface, lingual glands and lyssa in the above-mentioned four selected wild species of the Pantherinae and Felinae subfamilies. Macroscopic, histological, histochemical and ultrastructural analyzes were used in the present work. Comparative analyzes of the dorsal tongue surface showed the presence of mechanical lingual papillae on five subtypes of filiform papillae on the apex and body and conical papillae on the root of the tongue. Gustatory papillae in the four analyzed species were fungiform papillae and various numbers of vallate papillae. Foliate papillae were absent in P. leo bleyenberghi and L. lynx, while delicate smooth folds, which were separated by parallel grooves but without taste buds, were present in N. nebulosa. The vallate and foliate papillae were accompanied by lingual glands, which produced a serous secretion, whereas the mixed lingual glands of the lingual root were with a predominance of mucus secretions comparable to four captive Felidae species. In the median plane on the ventral surface of the apex under its epithelium and within the muscle fibers, the lyssa was also observed to a varying degree, with the least developed, and thought about the size of the entire tongue, was in P. leo bleyenberghi. The lyssa structure in the four species was dominated by adipose tissue. The obtained results contribute knowledge concerning the functional anatomy of the tongue in four selected Felidae species, especially in terms of comparative anatomy.

Validation of Medicinal Leeches (Hirudo medicinalis) as a Non-invasive Blood Sampling Tool for Hematology and Biochemistry Profiling in Mammals.

Blood sampling is a challenging procedure in many captive animals. Although manual restraint or anesthesia are usually possible, they entail intense stress and a high risk of injuries or organ failure. Blood sampling using medicinal leeches (Hirudo medicinalis) represents a promising non-invasive alternative to venipuncture; however, leech blood meal was to date used only for qualitative analyses such as genetic or serological screenings. Hence, the aim of this study was to evaluate the suitability of the leech blood sampling method for quantification of hematological and biochemical parameters. Medicinal leeches were manually applied on 67 zoo animals of eleven species, and control blood samples were obtained by venipuncture of the jugular vein. The leeches drew up to 20 ml of blood in 20 to 55 min. Although most hematological and biochemical parameters were significantly altered in leech-derived samples, their values showed strong (r = 0.62-0.79; 10/24 parameters) to very strong (r > 0.8; 13/24 parameters) correlations with venipuncture in all blood parameters, except for sodium (r = 0.39). As the parameter alterations and correlations were similar among species, simple cross-species regression formulas were sufficient to correct the alterations, thereby ensuring good repeatability between leeches and venipuncture in most parameters. Our data thus suggest that medicinal leeches can be used as a reliable non-invasive and stress-reducing alternative to standard venipuncture, even for quantitative assays. This opens new opportunities for a significant improvement to animal welfare in zoological gardens, conservation programmes, and ecophysiological research, where quantification of blood parameters is often needed.

Oral and Dental Examinations Findings in 15 Zoo Bolivian Squirrel Monkeys (Saimiri boliviensis) and Black-Tufted Marmosets (Callithrix penicillata).

As part of an annual wellness evaluation, we performed oral and dental examination under general anesthesia in 7 zoo Bolivian squirrel monkeys aged 10 and 15 years, and 8 zoo black-tufted marmosets aged between 1 and 7 years. No oral discomfort was observed in any animal prior to the procedure. Apart from dilacerated roots of second mandibular incisor teeth in Bolivian squirrel monkeys and one case of presumably odontodysplasia in a black-tufted marmoset, no major variations in number and shape of the present teeth and roots were revealed. All 15 animals had gingivitis, but periodontitis was only diagnosed in 3 black-tufted marmosets. Most commonly diagnosed dental pathology in Bolivian squirrel monkeys was attrition/abrasion, affecting 11.9% of all teeth, followed by caries, which was only diagnosed in older animals. Altogether 8 fractured teeth were diagnosed in Bolivian squirrel monkeys only, with root fracture being the most common type, followed by complicated crown fracture and complicated crown-root fracture. Radiographic signs of endodontic disease were found in 10 teeth in Bolivian squirrel monkeys and in one nonvital tooth with intact crown in a black-tufted marmoset. We associated high occurrence of caries in the older Bolivian squirrel monkeys with their diet and saliva characteristics of these animals. Lack of any periodontitis in Bolivian squirrel monkeys may partially be attributed to limitations of radiography technique, although squirrel monkeys appear to be far less susceptible to naturally occurring periodontitis than marmosets.

Detection of Antibodies against Tick-Borne Encephalitis Virus in Zoo Animals Using Non-Invasive Blood Sampling with Medicinal Leeches (Hirudo medicinalis).

Reports on non-invasive blood sampling are limited, and there are only a few studies on using kissing bugs (Reduviidae) and medicinal leeches (Hirudo medicinalis) for hematology and biochemistry testing in various zoo animal species. The aim of this study was to evaluate the usefulness of non-invasive blood sampling with medicinal leeches for arbovirus epidemiological investigations in various animal species from one zoo collection. Medicinal leeches were manually applied on 35 animals of 11 species. Control blood samples were obtained by venipuncture of the jugular vein. Antibodies to tick-borne encephalitic virus (TBEV) were detected by using the immunoenzymatic method or an immunofluorescent assay (IFAT), depending on the animal species. One of the 35 animals (2.9%) was seropositive (Ovis aries), whereas the rest of the samples were seronegative in both methods of sampling (non-invasive by leeches vs. invasive by venipuncture). Blood sampling using medicinal leeches showed promising results. It is likely a good alternative to other more complex and invasive methods, and it can provide significant advancement in blood sampling for preventive medicine and epidemiological studies in zoo animals.

Detection of Antibodies Against Tick-Borne Encephalitis Virus and Other Flaviviruses in a Zoological Collection in Slovenia.

Monitoring infectious diseases is one of the most important pillars of preventative veterinary medicine in zoological collections. The zoo environment offers a great variety of different animal species living in proximity and in contact with small wild animals and vectors (e.g., ticks and mosquitos). In this context, tick-borne encephalitis virus (TBEV), Usutu virus (USUV), and West Nile virus (WNV) causing vector-borne diseases are emerging pathogens that raise concern. The aim of the study was to detect antibodies to selected flaviviruses in various animal species in the Ljubljana Zoo, Slovenia. In total, 874 sera from 96 animal species were tested for antibodies to TBEV by enzyme-linked immunosorbent assays (ELISA); positive samples were confirmed by a virus neutralization test (VNT) using TBEV, WNV, and USUV antigens. Antibodies to TBEV were detected by ELISA in 3.9% (34/874) of zoo animals, with 4% (30/753) in mammals and 5% (4/86) in birds; the sera of reptiles (n = 34) and amphibians (n = 1) were negative. Antibodies to TBEV were confirmed by VNT in 11 mammals; one bird was positive for both WNV and USUV. The mixture of exotic animal species and their contact with wild animals and vectors such as ticks and mosquitos suggest that screening of infectious diseases in zoo animals might provide good insight into the epizootological situation of the area. This is the first survey of TBEV, WNV, and USUV in a zoological collection in Slovenia.

A Sentinel Serological Study in Selected Zoo Animals to Assess Early Detection of West Nile and Usutu Virus Circulation in Slovenia.

Monitoring infectious diseases is a crucial part of preventive veterinary medicine in zoological collections. This zoo environment contains a great variety of animal species that are in contact with wildlife species as a potential source of infectious diseases. Wild birds may be a source of West Nile virus (WNV) and Usutu (USUV) virus, which are both emerging pathogens of rising concern. The aim of this study was to use zoo animals as sentinels for the early detection of WNV and USUV in Slovenia. In total, 501 sera from 261 animals of 84 animal species (including birds, rodents, lagomorphs, carnivores, ungulates, reptiles, equids, and primates) collected for 17 years (2002-2018) were tested for antibodies to WNV and USUV. Antibodies to WNV were detected by indirect immunofluorescence tests in 16 (6.1%) of 261 animals representing 10 species, which were sampled prior to the first active cases of WNV described in 2018 in Slovenia in humans, a horse, and a hooded crow (Corvus cornix). Antibodies to USUV were detected in 14 out of 261 animals tested (5.4%) that were positive prior to the first positive cases of USUV infection in common blackbirds (Turdus merula) in Slovenia. The study illustrates the value of zoological collections as a predictor of future emerging diseases.

Biosurveillance of Selected Pathogens with Zoonotic Potential in a Zoo.

Monitoring of infectious diseases is one of the most important pillars of preventive medicine in zoos. Screening for parasitic and bacterial infections is important to keep animals and equipment safe from pathogens that may pose a risk to animal and human health. Zoos usually contain many different animal species living in proximity with people and wild animals. As an epidemiological probe, 188 animals (122 mammals, 65 birds, and one reptile) from a zoo in Slovenia were examined for selected pathogens. Antibodies to Toxoplasma gondii and Neospora caninum were detected by ELISA in 38% (46/122) and 3% (4/122) of mammals, and in 0% (0/64) and 2% (1/57) of birds, respectively; the reptile (0/1) was negative. A statistically significant difference in T. gondii prevalence was found in Carnivora compared to Cetartiodactyla and primate antibodies to Encephalitozoon cuniculi were detected by IFAT in 44% (52/118) of mammals and 20% (11/56) of birds, respectively; the reptile (0/1) was negative. Herbivores had a higher chance of being infected with E. cuniculi compared to omnivores. Antibodies to Chlamydia abortus and Coxiella burnetii were not detected in any of the 74 tested zoo animals. The sera of 39 wild rodents found in the zoo were also examined; they were negative for all three parasites. The parasite T. gondii was detected by PCR in the tissue of two mute swans (Cygnus olor), three eastern house mice (Mus musculus), one yellow-necked field mouse (Apodemus flavicollis), and one striped field mouse (A. agrarius). Positive samples were genotyped by a single multiplex PCR assay using 15 microsatellite markers; one sample from a mute swan was characterized as type II. This micro-epidemiological study offers a better understanding of pathogens in zoo animals and an understanding of the role of zoos in biosurveillance.

Outbreak of Human Metapneumovirus Infection in Zoo, Slovenia.

We report a case of human metapneumovirus infection that spread from humans to chimpanzees and back to humans. Bronchopneumonia developed in 4 of 6 members of a chimpanzee family, and 2 subsequently died. The chimpanzees' keeper also became ill. Sequencing showed 100% identity between virus sequences from chimpanzees and the keeper.

Microscopic structure of the tongue in the lesser hedgehog tenrec (Echinops telfairi, Afrosoricida) and its relation to phylogenesis.

The tongue of the lesser hedgehog tenrec (Echinops telfairi) was evaluated by light and scanning electron microscopy. Dorsal and lateral surfaces of the tongue were densely covered with various types of lingual papillae. Two types of mechanical papillae (filiform and conical) and two types of sensory papillae (fungiform and vallate) were observed. Rostrocaudally, the number of spikes in filiform papillae increased. Filiform, crown-like papillae were found on the radix, as well as large conical papillae with a wide base and a caudally bent single spike. Fungiform papillae were scattered in four rows on the dorsal surface. Three vallate papillae in inverse triangular layout were developed in the area of the lingual radix. Taste buds were found in the sensory papillae, i.e., fungiform and vallate. The lingual glands were predominantly seromucous. These glands were evenly scattered from the caudal portion of the lingual apex to the lingual radix. Purely serous glands were localized close to vallate papillae. A histochemical analysis of glands was performed. Results were compared to the Afrotheria (tenrec's relatives) and Eulipotyphla (animals with similar feeding habits to tenrecs). This study is the first description of the lingual morphology in the member of the Order Afrosoricida. Moreover, it compares the effect of the phylogenetic relation to the effect of the feeding habits on the lingual morphology.

RETROSPECTIVE STUDY OF CAUSES OF ANIMAL MORTALITY IN LJUBLJANA ZOO 2005-2015.

Zoos harbor large collections of diverse species, aiding in both conservation and education, as well as research in multiple scientific fields. However, the most common causes of death in zoo animals around the world remain unclear because few extensive reports or reviews are published on this topic. This information could greatly improve preventive veterinary medicine in zoologic gardens. This study provides a retrospective overview of the causes of death of animals from the Ljubljana Zoo in the years 2005-2015. During this period, a total of 353 animals were submitted for necropsy, of which 244 were mammals, 85 were birds, and 25 were reptiles. The causes of deaths were divided into infectious diseases (38%), dysfunctions of individual organs (20%), traumas (13%), parasitosis (7%), reproductive disorders (6%), metabolic disorders (3%), neoplastic disease (4%), and intoxications (4%). In some cases, the cause of death was unable to be determined (7%), most commonly because of autolysis of the body. The results of this retrospective study bring a general overview of the epizootiologic situation in the Ljubljana Zoo over an 11-yr period and valuable information to other zoos to optimize preventative plans and diagnostics.

Oral and Dental Examination Findings in a Family of Zoo Suricates ( Suricata Suricatta).

Although similar oral and dental diseases as seen in dogs, cats, ferrets, and other carnivores are expected in suricates, published data on their oral and dental diseases are rare. The objective of this report is therefore to describe oral and dental examination findings in a family of zoo suricates. In this cross-sectional clinical study, detailed oral and dental examination and full-mouth dental radiographs were performed in 6 suricates undergoing general anesthesia for their regular annual wellness check. Attrition/abrasion was commonly observed less so were dental fractures, but both conditions were found to be associated with endodontic disease. Periodontal disease of different stages was also commonly observed. As expected, dental radiography was essential to determine dental anatomy, to accurately diagnose oral and dental diseases, and to plan treatment. This report illustrates that several painful oral and dental diseases can affect suricates in captivity. Therefore, thorough oral and dental examination supported by dental radiography under general anesthesia is warranted also in these animals as a part of their annual wellness checks.

Tear production, intraocular pressure and conjunctival bacterial flora in selected captive wild ruminants.

OBJECTIVE: Evaluation of tear production (Schirmer's tear test, STT) and measurement of intraocular pressure (IOP) were performed in a population of captive wild ungulates in a Slovenian ZOO during routine annual health check. ANIMALS STUDIED: In total, 10 fallow deer (Dama dama), 25 mouflons (Ovis aries musimon), 20 alpine ibexes (Capra ibex), and three alpine chamois (Rupicapra rupicapra) were included in the study. METHODS: Tear production was performed by Schirmer's tear test, IOP was measured with an applanation tonometer, and ophthalmological examination was conducted with slit-lamp biomicroscopy and indirect ophthalmoscopy. Conjunctival swabs were taken and submitted for aerobic bacteriology and for detection of Chlamydia spp. and Mycoplasma spp. tested by PCR. RESULTS: Average tear production (in mm/min) was 17.8 ± 3.16 for fallow deer, 17.9 ± 3.87 for mouflons, and 11.7 ± 3.87 for ibexes. Mean intraocular pressure (IOP, in mm Hg) was 14.1 ± 2.48 for fallow deer, 14.9 ± 2.20 for mouflons, and 13.1 ± 2.43 for ibexes. For chamois, average tear production and IOP were 14.5 ± 3.0 and 10.2 ± 2.5, respectively; this is the first record of STT I and IOP in chamois. Bacteriological swabs were positive for bacteria in 100% of the fallow deer, 56% of mouflons, 35% of ibexes, and 100% of chamois. Gram-positive bacteria were predominant. Moraxella spp., Chlamydia spp., and Mycoplasma spp. were not detected. CONCLUSION: The reported values were obtained in animals under manual restraint only to be applicative in similar conditions.

An eight-year survey of the intestinal parasites of carnivores, hoofed mammals, primates, ratites and reptiles in the Ljubljana zoo in Slovenia.

Problems with parasitic infections and their interspecies transmissions are common in zoological gardens and could pose serious health damage to captive animals. This study presents results of eight-year monitoring of intestinal parasites in animals from Zoo Ljubljana, Slovenia. A total of 741 faecal samples from 40 animal species were collected two to four times per year and examined microscopically. Intestinal parasites were detected in 45% of samples, with detection of helminths (Cestoda, Nematoda - Ascaridida, Enoplida, Strongylida, Oxyurida, Rhabditida and Trichurida) and protists (Apicomplexa and Ciliophora) in 25% and 13% of samples, respectively; mixed infection was found in 7% of samples. The mostly infected were ungulates (61%), followed by reptiles (44%), ratites (29%), primates (22%) and carnivores (7%). During the observation period, the number of infected animal species increased from 8 to 25. This is the first long-term monitoring study of intestinal parasites in zoo animals from Slovenia. Routine monitoring of parasitic infection and regular deworming and hygienic measures are necessary to prevent gastrointestinal infections in captive animals.

Light and scanning electron microscopy of the tongue of a degu (Octodon degus).

The tongue of an adult degu was examined by light and scanning electron microscopy. It consists of an apex, corpus, and radix and contains a lingual prominence. The aim of this study was to describe the course of muscle fascicles of the proper lingual muscle, the presence and nature of the lingual salivary glands, and particularly the appearance and distribution of the lingual papillae. Three major types of papillae have been observed: filiform, conical, and vallate. The dorsal surface of the lingual apex extends in caudally bent filiform papillae with two spines. The lingual corpus bears long filiform papillae with a single tip. The lingual radix contains crown-like papillae in the region of the prominence and conical papillae in the remaining areas. Two oval vallate papillae were discovered caudally on the lingual radix. This first description of the lingual structures in a degu could be used for comparative studies or as basic data for differentiation of lingual morphology in this species.