Exploration of Social Proximity and Behavior in Captive Malayan Tigers and Their Cubs.

The survival of endangered felids is becoming increasingly dependent on the successful management and breeding of reserve populations in captivity. While most felid species are reported to be solitary in the wild, increasing evidence suggests that some big cats have greater social plasticity than is currently acknowledged. This social plasticity allows felids to be sometimes socially housed in environments such as zoos and rescue centers. While the effects of such shared enclosures remain in question, many reports provide evidence of several welfare benefits of maintaining these large carnivores in pairs or even groups. Since 2019, Le Parc des Félins has housed a breeding pair of Malaysian tigers (Panthera tigris jacksoni) alongside their offspring. The purpose of this study was to quantify the social affiliation between the male tiger and his cubs and to investigate the female's tolerance toward him. The data were collected using video recordings in the outdoor enclosure when social interactions were observed. The data were coded and categorized in the open-source software BORIS, from which behavioral activity budgets were calculated. Data were analyzed using the chi-squared test for association to determine differences in affiliative frequency, with directed and undirected sociograms created to visualize individual relationships. Overall, the male regularly engaged in affiliative behaviors with the cubs, with no significant difference found in the frequency of interactions with them compared to the female. No physical aggression was directed by the male toward the cubs. Although the female maintained a stronger bond with the cubs compared to the male, he displayed a greater range of affiliative behaviors toward them than male tigers are thought to exhibit. Both adults showed a high degree of tolerance toward their conspecifics, suggesting that maintaining breeding pairs with their offspring is a viable management strategy in zoological collections. This study could therefore improve husbandry and conservation practices by developing our understanding of felid sociality and the potential welfare benefits of social housing, allowing for evidence-based captive management decisions.

AMYLOIDOSIS IN CARACALS (CARACAL CARACAL).

Nine cases of amyloidosis in caracals (Caracal caracal) from three different institutions in Europe were reviewed and evaluated histopathologically. The six males and three females died between 2008 and 2018 at an age of 6 yr ± 2.5 mo (median ± interquartile range). In two out of nine (2/9) animals, amyloidosis was an incidental postmortem finding; the animals died of bronchopneumonia and gastric ulceration due to Helicobacter spp., respectively. Seven (7/9) animals suffered from acute renal failure due to amyloidosis, one of them additionally of cardiac decompensation. The predominant clinical signs were weight loss, lethargy, dys- or anorexia, dehydration, increased BUN and creatinine, and azotemia. The main gross lesion was a pale renal cortex on cut surface; in two animals, the kidneys appeared enlarged. Histologically, glomerular amyloid was present in every animal (9/9), and was the predominant renal manifestation of amyloidosis. Additional findings included splenic amyloid (8/8), amyloid in the lamina propria of the intestine (5/5), and amyloid in the lingual submucosa (4/4). Gastric mineralization was present in four animals suffering from renal failure. In the animal dying from bronchopneumonia, severe pancreatic amyloid deposits mainly affecting the exocrine pancreas (1/5) were identified. Immunohistochemistry was employed to identify amyloid AA in eight cases; only in the caracal dying from bronchopneumonia AA was amyloid confirmed. In several organs, especially in those where only small amyloid deposits were detected, a Congo red stain was often necessary to confirm the deposition. The etiology of the amyloidosis remains unknown. Three caracals were related within two generations, another three within four generations, so one might hypothesize a familial trait. In conclusion, amyloidosis should be considered as a significant disease in the caracal. Particularly in cases with renal disease, it should be included as a major differential diagnosis.

Hematuria and urinary bladder lesions compatible with bracken fern (Pteridium aquilinum) intoxication in captive fallow deer (Dama dama).

Hemangiosarcoma, hemangioma, transitional cell carcinoma, and chronic cystitis were diagnosed in the urinary bladder of six captive fallow deer (Dama dama). Hematuria and thin body condition were observed in the advanced cases. These findings were compatible with chronic enzootic hematuria and were suspected to have been induced by chronic ingestion of bracken fern (Pteridium aquilinum) present on the premises. These lesions were similar to those described in bovine enzootic hematuria in cattle. Hemangiosarcoma metastases, hydronephrosis, and renal carcinoma were also associated in some cases. This is the first report of hemangioma, hemangiosarcoma, transitional cell carcinoma, and renal carcinoma of the urinary bladder in fallow deer and the first indication of bracken fern intoxication in deer.