Fatal infection in two Icelandic stallions caused by Halicephalobus gingivalis (Nematoda: Rhabditida)

Opportunistic infections with the free living nematode Halicephalobus gingivalis are infrequently reported in horses but the cases are widespread geographically. The nematodes are believed to penetrate wounds and subsequently reproduce within the host tissues. This paper reports two cases of a fatal disease in stallions of the Icelandic breed in Iceland. Case 1: a stallion, which sustained injuries to the mouth after an accident, developed severe neurological signs and had to be euthanatized. Histological examination revealed mild inflammation and malacia in the cerebellum associated with the presence of numerous H. gingivalis nematodes. Case 2: a stallion that started swerving to one side and lost balance was euthanatized due to lack of response to therapy and rapid deterioration. Histological examination revealed numerous H. gingivalis nematodes in the cerebellum, brain stem, cervical spinal cord and in the meninges, with minimal reactive changes. In case 1 the infection presumably was acquired by nematodes from soil penetrating through wounds in the mouth. The mode of the H. gingivalis infection in case 2 is uncertain. These are the first cases of H. gingivalis infection reported from Iceland and the second report from the Nordic countries.     

Halicephalobus gingivalis (Nematoda) infection in a Grevy's zebra (Equus grevyi).

A 6-yr-old female Grevy's zebra (Equus grevyi) with a disseminated rhabditiform nematode infection is described. Antemortem clinical signs were limited to blindness and abnormal behavior believed to be caused by a recurrent nematode-induced uveitis. Histologic examination of the kidneys, heart, eyes, uterus, and lymph nodes revealed granulomas containing multiple sections of rhabditiform nematodes. Most of the recovered nematodes were larval stages with only a few adult females noted. The adults measured 243-297 microm x 11-16 microm (x = 269 x 14 microm). The distinctive rhabditiform esophagi had corpus:isthmus:bulb proportions of 19:11:5. On the basis of adult morphology, the nematode was identified as Halicephalobus gingivalis. This is the first report of this parasite in a zebra and indicates that this parasitic granulomatous disease should be considered in zebras with neurologic disease.     

Halicephalobus gingivalis infection in a 5-year-old Tinker gelding

A 5-year old Tinker gelding was referred to the Department of Equine Sciences with a left eye uveitis and fever. At presentation the horse showed a mild lethargy, fever and decreased vision of the left eye. Rectal examination revealed an enlarged left kidney, with a hard and an irregular surface. The cranial mesentery artery had an enlarged and irregular aspect. Blood analysis showed anaemia, leucocytosis, increased blood urea nitrogen and creatinine and a hyperproteinemia. Urine analysis repeatedly showed a marked proteinuria and an increased gammaGT/creatinine ratio. The amount of abdominal fluid was slightly increased. However, the aspect, amount of cells and protein were normal. In the following two days the fever persisted and the horse showed anorexia and severe neurological signs. The horse was euthanized with permission of the owner. Post mortem examination showed a generalized parasitic infestation of Halicephalobus gingivalis in the uvea of the left eye, the kidneys and the central nerve system.     

Halicephalobus gingivalis encephalomyelitis in a horse

An 8-year-old, Arabian mare presented with acute progressive ataxia and a firm swelling over the right mandible. Radiographs revealed multiple radiolucent areas on the mandibles. The mare's neurological signs progressed, she was consequently euthanized. Postmortem examination revealed mandibular granulomatous reactions and meningoencephalitis due to the nematode Halicephalobus gingivalis.     

Radiculomeningomyelitis due to Halicephalobus gingivalis in a horse

An adult horse was euthanatized following a clinical diagnosis of cauda equina neuritis. Significant gross postmortem and histopathologic findings were limited to the sacral spinal cord and cauda equina. The sacral spinal cord, meninges, and spinal nerve roots were expanded and partially effaced by sclerosing granulomatous inflammation with necrosis. The lesion contained numerous nematode larvae and fewer adults with a rhabditiform esophagus having a corpus, isthmus, and valved bulb. Female nematodes were amphidelphic and didelphic with reflexed ovaries. These morphologic features confirm Halicephalobus gingivalis as a novel cause of clinical signs in this case of cauda equina neuritis.     

Treatment of a granuloma caused by Halicephalobus gingivalis in a horse.

A 12-year-old Arabian gelding with a granuloma caused by the nematode Halicephalobus gingivalis caudal and dorsal to the left orbit was examined. There was no evidence of dissemination of the nematode to the kidneys or the CNS, and the horse was treated with ivermectin (1.2 mg/kg [0.55 mg/lb] of body weight, p.o., every 2 weeks for 3 treatments). The granuloma was surgically debulked 2 days after the first dose of ivermectin. The granuloma resolved with no evidence of nematode infection after 18 months. Halicephalobus gingivalis is a ubiquitous saprophytic nematode that has been reported to infect humans and horses. The nematode may form granulomas in the integument or may disseminate to various organs with a tropism for the CNS and kidneys. Once clinical signs of CNS involvement develop, the disease is rapidly fatal.     

Study of laryngopharyngeal pathology in Thoroughbred horses in southern California

Reasons for performing study: There is increasing anecdotal evidence among horse owners, trainers and equine clinicians of a high prevalence of subepiglottic ulcers, suggested to have a negative effect on racing performance. Objectives: To provide a prevalence study and pathological characterisation of laryngopharyngeal lesions with emphasis in the subepiglottic area and, in particular, subepiglottic ulcers. Methods: The study was carried out on 91 Thoroughbred racehorses received for post mortem examination from 4 major Southern California racetracks. The most common reason for submission was catastrophic musculoskeletal injury, but others include sudden death, laminitis, colic, colitis, neurological disorders, pleuropneumonia and arytenoid chondropathy. Laryngopharyngeal specimens were collected and examined grossly; selected cases were also examined histopathologically. Results: Thirteen horses (14.3%) had at least one type of laryngopharyngeal abnormality, 7 horses (7.7%) had lesions in the subepiglottic soft tissues, including 4 subepiglottic ulcers, 2 soft palate ‘kissing lesions' and one 'subepiglottic scar’. Eight horses (8.8%) had lesions elsewhere in the laryngopharynx, including mucosal ulcerations, arytenoid chondropathy, epiglottic entrapment and partial absence of arytenoid cartilage. Conclusions and potential relevance: Lesions in the subepiglottic area were among the most prevalent in this study, suggesting that an important percentage of laryngopharyngeal abnormalities may be missed during routine endoscopy of the standing horse, which often does not include the examination of subepiglottic tissues. Pathologically, subepiglottic ulcers were chronic‐active with viable hyperplastic epithelial margins, suggesting that proper healing and re‐epithelialisation should occur with appropriate treatment. In most cases, the lesions observed do not necessarily indicate a clinical problem and more extensive prevalence studies and correlation between abnormalities found and performance are needed to assess the clinical relevance of subepiglottic soft tissue lesions accurately.     

Granulomatous nephritis and meningoencephalomyelitis caused by Halicephalobus gingivalis in a pony gelding

A ten-year-old Shetland pony gelding showed low appetite, ataxia, peculiar swaying, clouding of consciousness, and ultimately died. At necropsy, multiple coalescing granulomatous foci were detected in the kidneys, and small necrotic lesions were found in the cerebellum. Histologic examination of the renal tissue sections revealed extensive granuloma, and Halicephalobus gingivalis-like nematodes were seen. Similar nematodes were found in the granulomatous or necrotic lesions of the renal lymph nodes and cerebellum, and were also frequently detected in cerebrospinal meningovascular lesions. Morphologic features together with partial ribosomal RNA gene sequences of the nematodes in the lesions revealed that they were H. gingivalis. The present results indicated that H. gingivalis caused granulomatous nephritis and meningoencephalomyelitis in this pony gelding.     

Intramuscular desmoid tumor (musculoaponeurotic fibromatosis) in two horses.

Intramuscular desmoid tumors (musculoaponeurotic fibromatosis) were discovered in two young adult horses. The tumor in one horse was in the lateral cervical musculature, and that in the second horse occurred in the pectoral musculature. Histopathologic features were similar in both horses and included proliferation of fibroblasts and cells expressing muscle actin (myofibroblasts), with extensive dissecting fibrosis within muscle. These features are similar to those of desmoid tumors in humans, particularly those also known as musculoaponeurotic fibromatosis. Dissection of these lesions revealed a single central (horse No. 1) or multiple central (horse No. 2) fluid-filled cavities with associated sterile inflammation. The presence of these cavities supports the hypothesis that equine desmoid tumors are traumatic in origin, possibly occurring at sites of injections or bursal rupture. Surgical excision of the tumor in horse No. 1 was apparently curative, but the extent of the tumor in horse No. 2 precluded surgical excision.     

Histoplasmosis infection in two cats from California

Systemic mycotic infections are typically localized to specific geographic regions of the country, because the organisms involved have certain environmental requirements for growth. Suspicion of infection relies on travel to or residence in recognized endemic regions. This report describes infection with histoplasmosis in two indoor cats from central California, an area not considered to be endemic for the disease. Systemic mycotic infections should be considered as differential diagnoses in any cat with compatible clinical signs, regardless of travel history or residence, especially if the cat is presented within a recognized endemic region.     

Neoplasia associated with feline immunodeficiency virus infection in cats of southern California.

Between 1988 and 1991, feline immunodeficiency virus (FIV) infection status was evaluated in 1,160 cats examined at an oncology referral and general practice in Los Angeles, California. Twenty-nine (2.5%) cats were FIV positive. Neoplasia was present in 18 of the 29 (62%) cats. Sampling for neoplasia was intentionally biased in the oncology referral group. However, 33% (6/18) of FIV-infected cats with neoplasia originated from the general practice. Three neoplastic processes were observed; myeloproliferative disease (MPD; 5/18), lymphoma (LSA; 5/18), and squamous cell carcinoma (SCC; 7/18). One cat had LSA and SCC. Extranodal sites of LSA were common (66%) in FIV-infected cats. Sites of LSA were submandibular and mesenteric lymph nodes, liver, kidneys, periorbital area, and diffuse (heart, pancreas, bladder). Sites of SCC were sublingual (n = 2), nasal planum (n = 3), nasal planum and eyelids (n = 1), and mandible (n = 2). Feline leukemia virus co-infection was observed in 17% (5/29) of FIV-infected cats. The FIV-infected cats with MPD were young (range, 8 months to 13 years; median, 4 years) and had short survival duration (2, 6, 21, 134, 249 days) even in response to aggressive treatment. The FIV-infected cats with LSA were older (median age, 8 years; range, 4 to 14 years) and survived 60 days if untreated. Cats administered chemotherapy survived 39, 45, 217, and 243 days; the latter 2 cats had partial remission of 2 months' duration. Older FIV-infected cats had SCC (median age, 12 years; remission range, 7 to 16 years) because of more frequent association of both diseases in older cats with outdoor environment.(ABSTRACT TRUNCATED AT 250 WORDS)