Major histocompatibility complex and mate choice in the polygynous primate: the Sichuan snub‐nosed monkey (Rhinopithecus roxellana)

The highly polymorphic genes within the major histocompatibility complex (MHC) not only play a major role in immunity resistance, but also seem to provide hints for mate choice in some animal populations. In the present study we investigated MHC‐related mate choice in a small natural population (group size 40–55 individuals) of a polygynous primate, the Sichuan snub‐nosed monkey (Rhinopithecus roxellana). We found that there was no evidence either for MHC‐disassortative mating, or for females to mate with males based on MHC heterozygosity or specific alleles. Nevertheless, of the 11 alleles identified, we found that the frequencies of 2 alleles, Rhro‐DRB2 (P < 0.01) and Rhro‐DRB5 (P < 0.05) were higher in offspring than in their parents. These findings suggest that MHC‐DRB in this population of R. roxellana is unlikely to be associated with mating preferences. Limited female opportunities for mate choice are likely due, in part, to the harem breeding structure present in R. roxellana, and the relatively small number of resident adult males in our study band (N = 4–6). In addition, we suggest that differences in the frequency of particular alleles across generations may be linked to parasite resistance in a fluctuating environment; however, confirmation of this finding requires further study.     

Presumptive Nocardia spp. infection in a dog treated with cyclosporin and ketoconazole

Abstract

CASE HISTORY: A dog that had received 8 months of cyclosporin and ketoconazole therapy for treatment of atopic dermatitis subsequently developed severe neurological disease, that failed to respond to treatment with trimethoprim-sulphadiazine and clindamycin.

HISTOPATHOLOGICAL FINDINGS: Histopathological examination of the pulmonary parenchyma and spinal cord revealed loose aggregates of Gram-positive, partially acid-fast, fine, beaded, filamentous bacteria, most consistent with Nocardia spp.

DIAGNOSIS: A presumptive diagnosis was made of disseminated nocardiosis of the spinal cord and lungs.

CLINICAL RELEVANCE: Nocardia spp. is an opportunistic actinomycete that may cause disseminated disease, particularly in immunocompromised animals. Cyclosporin is used in veterinary medicine to control immune-mediated and allergic disorders, with few reported adverse side effects. This case gives further evidence that involvement of the spinal cord in nocardiosis of the central nervous system (CNS) carries a poor prognosis, and opportunistic infection by Nocardia spp. may be a potential complication of immunosuppressive cyclosporin therapy in the dog.     

A retrospective survey of riders' opinions of the use of saddle pads in horses

Horse riders have used layers between saddles and their horse's back since ancient times. Despite the apparent common usage of such layers, most research regarding pressures under horses' saddles seems to have been conducted without such layers present. An online survey of equestrian riders was conducted to quantify the use of such layers and how the layers behaved during use. This produced 1,011 responses from participants in 16 equestrian activities. More than 98% of respondents reported they used some form of layer between their horse's back and the saddle. Differences in layer usage were associated with the respondent's preferred riding discipline and the wither type of their horse. Compensation for perceived saddle fit problems was commonly cited as a reason for using layers. Although horse comfort was nominated by 87.5% of respondents as a reason for using a layer between saddle and the horse's back, many respondents (45%) reported using more than 1 layer. This often resulted in layers thicker than 1 cm, which paradoxically could compromise horse welfare. Half of the respondents reported that the layer between the saddle and the horse's back slipped during riding. Although some significant risk factors for this slippage were identified, they are deemed not to be definitive because of similar factors being identified by the group who did not report layer slippage. These results suggest that incorrect usage of layer between saddles and horses' backs can sabotage good saddle design and compromise equine welfare. Future research on the layers used between the saddles and horses' back is warranted. The question of whether using thicker layers can create greater pressure under saddles or improve rider–horse communication also needs to be investigated.     

Gamna‐Gandy bodies: a case of mistaken identity in the spleen of a cat

A 4‐year‐old, female spayed Domestic Shorthair cat was presented for a 2‐day history of lethargy, anorexia, and vomiting. Diagnostic assessments revealed a severe, regenerative anemia and the presence of a solitary, 3 × 4 cm splenic mass. Cytologic examination of fine‐needle aspirates of the splenic mass showed sheets of pleomorphic histiocytic cells with numerous intracellular and extracellular, negatively staining to deeply basophilic, branching structures. These structures were typically of thin uniform thickness with random angled branching that formed geometrical shapes and fragments, occasionally with sharpened ends and a crystalline appearance. Septal‐like divisions were irregularly spaced along some of the linear branches. The cytology was interpreted as a probable histiocytic inflammatory response to the unidentified foreign material with histiocytic sarcoma as a differential diagnosis. Histopathologic evaluation of the splenic mass resulted in a diagnosis of histiocytic sarcoma. The branching material stained positively for both iron and calcium, indicating that the material was compatible with Gamna‐Gandy bodies present secondary to tumor‐associated hemorrhage and the formation of calcium–iron complexes.