Hypokalemia, muscle weakness, and recumbency in dairy cattle.

Seventeen cases of severe hypokalemia (serum or plasma potassium < or = 2.1 mEq/L) in association with profound muscle weakness and recumbency in lactating dairy cattle were included in a retrospective study. The cattle were from 15 different farms. Eleven of the 17 animals were recumbent at presentation while the remaining six became recumbent within 6 hours of admission. Both multiparous cows (n = 11) and first calf heifers (n = 6) were included. The median days in milk was 21 (range: 5 to 110), and chronic, recurrent ketosis (15 of the 17 cases) was the most common preexistent condition. Potential musculoskeletal and neurologic causes of recumbency were ruled out on the basis of physical examination and ancillary diagnostics. Ten of the 17 animals were euthanized and underwent full necropsy examination that demonstrated ischemic muscle damage and varying degrees of hepatic lipidosis. Aggressive potassium supplementation was instituted in all 17 cases either orally, intravenously, or by a combination of both routes. In the seven individuals that survived, potassium supplementation was administered orally and intravenously in five, orally only in one, and intravenously only in one.

Presumed clostridial and aerobic bacterial infections of the cornea in two horses.

Microscopic examination of Gram-stained tissue specimens collected from severe corneal ulcers in 2 horses revealed large gram-positive rods suggestive of Clostridium spp. Clostridium perfringens was isolated from specimens collected from horse 1; anaerobic organisms were not detected in specimens from horse 2. Aerobic bacterial culture revealed Aeromonas hydrophila and Enterobacter cloacae in specimens collected from horses 1 and 2, respectively. An insect exoskeleton was presumed to be the underlying cause of ulceration in horse 1. Cause of ulceration in horse 2 was not determined. Antibiotics used to treat the corneal infections included ticarcillin disodium-clavulanic acid injected one time subconjunctivally and chloramphenicol applied topically at frequent intervals. Horse 2 also received penicillin or trimethoprim-sulfadiazine. Small leukomas were the only lesion remaining between 2 and 7 months after initial evaluation. Chloramphenicol applied topically appears to be an effective treatment against clostridial corneal infections in horses.

Ocular manifestations of equine motor neuron disease.

The characteristics of the ocular manifestations of equine motor neuron disease (EMND) are described. Forty-two horses with histories, clinical signs and necropsies compatible with EMND were the subjects of this study. Ophthalmoscopic lesions that varied in severity were found in 40 of 42 horses and appeared as a distinct pigmented reticulated pattern at the tapetal-nontapetal junction or throughout the fundus, depending upon severity. The pattern colours ranged from yellow brown to black. Areas of hyperreflectivity formed mosaic patterns in the tapetal fundus. ERG B-wave amplitudes were usually at least 50% reduced and many animals showed extinguished amplitudes. None of the horses had apparent visual impairment. Histopathologically, all 42 horses had retinal pigment epithelial (RPE) congestion with ceroid-lipofuscin. Retinal degeneration was variable even within the eyes. Thin layer chromatography (TLC) analysis of the RPE and neural retina identified both green and orange emitting fluorescent compounds not found in normal horses. All unsupplemented horses had plasma vitamin E levels <1.0 microg/ml. The potential significance of this report is the pathognomonic role the ocular manifestations exhibit in helping to diagnose equine motor neuron disease.

Paraneoplastic pruritus and alopecia in a horse with diffuse lymphoma.

An 8-year-old castrated male Paint Horse was referred because of generalized pruritus, alopecia, and intermittent fever. Results of gross evaluation of the skin and microscopic evaluation of skin scrapings were inconclusive. Histologic examination of skin biopsy specimens revealed vasculitis. The horse had persistent hypercalcemia; therefore, lymphosarcoma was considered a possibility. Ultrasonography revealed hypoechoic nodules within the parenchyma of the spleen and liver. Results of microscopic evaluation of an aspirate from a splenic nodule were suggestive of lymphosarcoma. The condition of the horse deteriorated, and it was subsequently euthanatized. Postmortem examination revealed diffuse lymphoma. In human beings, generalized pruritus may be an indication of serious internal disease, including malignancy. Paraneoplastic pruritus is most common in patients with Hodgkin's lymphoma but can also develop in patients with non-Hodgkin's lymphoma, leukemia, or a solid neoplasm. Lymphoma should be considered in the differential diagnoses when examining horses with generalized pruritus for which another cause cannot be identified.

Clinical appearances, healing patterns, risk factors, and outcomes of horses with fungal keratitis: 53 cases (1978-1996)

OBJECTIVE: To compare initial clinical appearances, healing mechanisms, risk factors, and outcomes of horses with fungal keratitis. DESIGN: Retrospective analysis. ANIMALS: 52 horses (53 eyes) with fungal keratitis. PROCEDURE: Medical records and clinical photographs of eyes were reviewed. Keratomycoses were categorized on the basis of clinical appearance at initial examination and pattern of healing. RESULTS: Five distinct forms of mycotic keratitis were recognized. Of 53 affected eyes, 34 (64%) retained sight and had varying degrees of corneal scarring after treatment, 6 (11%) had a cosmetic appearance but were blind, and 13 (25%) were enucleated. Bacterial-like ulcers were the most frequent type and the most difficult for predicting outcome. Eyes affected by superficial fungal keratitis were likely to be chronically infected and to require debridement and extended treatment but usually healed with minimal scarring. Keratomycosis with a surrounding furrow resulted in a grave prognosis. Aspergillus organisms were isolated from 9 of 10 such eyes. Cake-frosting material was a positive prognostic sign. Fungal corneal stromal abscesses tended to be caused by yeast. CLINICAL IMPLICATIONS: This information will aid practitioners in recognizing various forms of fungal keratitis and guide them when making therapeutic decisions and prognoses for affected horses.

Concurrent abomasal displacement and perforating ulceration in cattle: 21 cases (1985-1996).

OBJECTIVE: To evaluate the association of physical examination and clinicopathologic findings with surgical findings in cattle with concurrent abomasal displacement and perforating ulceration, to determine short- and long-term survival rates in these cattle, and to determine whether degree of peritonitis (focal vs diffuse) influences survival rates. DESIGN: Retrospective study. ANIMALS: 21 cattle with concurrent abomasal displacement and perforating ulceration and 42 cattle with uncomplicated abomasal displacement. PROCEDURE: Information on signalment, stage of lactation, physical examination findings, clinicopathologic data, surgical diagnosis, procedure(s) performed, and necropsy findings were retrieved from medical records of all cattle included in this study. Differences between physical examination findings of cattle with concurrent disease and those of cattle with uncomplicated displacements were evaluated, as were differences between survival rates in cattle with focal versus diffuse peritonitis. RESULTS: Cattle with concurrent disease had a greater probability of having pneumoperitoneum and signs of abdominal pain identified on physical examination than did cattle with uncomplicated diseases. There was no relationship between clinicopathologic data and survival time. Short-term survival rate was 38%, and degree of peritonitis significantly influenced survival time in cattle with concurrent abomasal displacement and perforating ulceration. Long-term survival rate in these cattle was 14%. CLINICAL IMPLICATIONS: Cattle with concurrent displaced abomasum and perforating ulceration have a poor chance for survival. In addition to detection of displaced abomasum, physical examination findings that can help lead to a presurgical diagnosis of this syndrome are pneumoperitoneum and signs of abdominal pain.

Ocular lesions in horses with lymphosarcoma: 21 cases (1977-1997).

OBJECTIVE: To determine the most common ocular lesions in horses with lymphosarcoma. DESIGN: Retrospective study. ANIMALS: 79 horses histologically confirmed to have lymphosarcoma. PROCEDURE: Ophthalmic examinations were performed by a single individual. RESULTS: 21 of 79 horses had lesions involving the eye or ocular adnexa. Infiltration of the palpebral conjunctiva and eyelids was the most common lesion (n = 11). Other lesions included uveitis (n = 4), corneoscleral masses (2), third eyelid masses (2), and diffuse retrobulbar infiltrates (2). CLINICAL IMPLICATIONS: In horses with lymphosarcoma, ocular lesions may precede or be more obvious than lymph node enlargement or signs of visceral involvement. Early recognition of ocular lesions suggestive of lymphosarcoma may allow a more rapid diagnosis of lymphosarcoma in horses.

Tumors of the eye and ocular adnexal tissues.

This article reviews options in dealing with tumors of the cornea and conjunctiva, nictitating membrane neoplasms, and eyelid neoplasms. Orbital tumors, optic nerve and other intraocular tumors are also discussed.

Cholelithiasis and cholecystitis in a dairy cow.

A 9-year-old Holstein cow was evaluated for colic and decreased milk production of 2 days' duration. Preoperative serum biochemical results suggested hepatic damage and cholestasis. On the basis of persistent signs of abdominal pain that were nonresponsive to analgesics, exploratory laparotomy was performed. The cow was found to have choleliths. Cholecystocentesis was performed, and samples were submitted for cytologic examination and bacterial culture. Bacterial culture yielded Escherichia coli and Clostridium perfringens. Using digital pressure, choleliths were reduced until they could be passed through the bile duct into the duodenum. The cow recovered from surgery without complications, and all serum biochemical test results returned to reference ranges. Cholelithiasis is rare in cattle but can result in signs of abdominal pain.

Evaluation of itraconazole-dimethyl sulfoxide ointment for treatment of keratomycosis in nine horses.

OBJECTIVE: To evaluate the efficacy of itraconazole-dimethyl sulfoxide ointment for treatment of keratomycosis in horses in the northeastern United States. DESIGN: Prospective clinical trial. ANIMALS: 9 horses (10 affected eyes). PROCEDURE: All horses treated for keratomycosis at Cornell University between July 1994 and July 1996 were included in the study. The diagnosis of keratomycosis was confirmed by cytologic examination, and all horses were treated with 0.25 ml of a 1% itraconazole-30% dimethyl sulfoxide petrolatum-based ointment, applied to the affected eye every 4 hours. RESULTS: Topical application of itraconazole-dimethyl sulfoxide ointment (q 4 h) resolved keratomycosis in 8 of 10 eyes; mean duration of treatment was 34.6 days (range, 16 to 53 days). CLINICAL IMPLICATIONS: Results of this study indicate topical administration of itraconazole-dimethyl sulfoxide ointment may provide an additional treatment option for horses with keratomycosis.

Multicentric schwannomas causing chronic ruminal tympany and forelimb paresis in a Holstein cow.

A nine-year-old Holstein cow that developed recurrent ruminal tympany and an abnormal forelimb gait and posture ultimately became recumbent and unable to rise, and was euthanased. A postmortem examination demonstrated numerous schwannomas affecting peripheral nerves and several thoracic and abdominal viscera.

Corneal concentrations and preliminary toxicological evaluation of an itraconazole/dimethyl sulphoxide ophthalmic ointment.

The objectives of this study were to determine the concentration of itraconazole achieved in corneal tissue and aqueous humour after topical application of a 1% itraconazole ointment: to determine the effect of including dimethyl sulphoxide (DMSO) in the ointment on achievable ocular tissue itraconazole concentrations; and to assess if any gross or histopathologic ocular toxicity results from the topical application of 1% itraconazole with or without the addition of DMSO. The experimental trial consisted of 6 horses considered to have normal eyes. Each horse had one eye treated with 0.3 mL of 1% ultra-micronized itraconazole ointment and the fellow eye with 0.3 mL of 1% itraconazole/ 30% DMSO ointment. The ointment was applied every 6 h for a total of 28 treatments. Both ointments were well tolerated and no gross or histopathologic abnormalities developed during the trial. Corneal tissue and aqueous humour concentrations of itraconazole were determined using high performance liquid chromatography. Corneal tissue concentration averaged 1.1 (+/- 0.4) micrograms/g in horses treated with the 1% ultramicronized itraconazole ointment and 7.9 (+/- 3.3) micrograms/g for those treated with the 1% itraconazole/30% DMSO ointment: there was a statistically significant difference between ointments (P = 0.005) No itraconazole could be detected in the aqueous humour in either treatment group.

Ocular emergencies.

Most ocular and orbital injuries or acute ocular inflammation in horses result in similar signs of adnexal swelling, photophobia, blepharospasm, and lacrimation. It is hoped that detailed examination and the suggestions in this article will enable veterinarians attending horses having ocular emergencies to arrive at a correct diagnosis and appropriate therapy.

Lack of residual lung damage in horses in which Rhodococcus equi-induced pneumonia had been diagnosed.

The effect of prior Rhodococcus equi-induced pneumonia on pulmonary health was investigated in 5 horses (< 24 months old) using endoscopy, radiography, hematologic and bronchoalveolar lavage analyses, and pulmonary function testing. Rhodococcus equi-induced pneumonia had been diagnosed in principal horses when they were foals. Diagnosis was based on positive results of transtracheal aspiration and thoracic radiography at the time of initial clinical examination. Results of reevaluation of the respiratory system of these horses (R+) were compared with those of 5 age-matched healthy horses (R-) that lacked clinical or historical evidence of foalhood pneumonia. Significant differences in variables between the 2 groups of horses were not evident. In both groups, most horses had radiographic evidence of an accentuated bronchointerstitial pattern, although results of analysis of bronchoalveolar lavage specimens were normal and mononuclear cells predominated. Variability in results of the pulmonary function tests was observed within the between the 2 groups of horses. Only normalized dynamic lung compliance was slightly lower in the previously infected horses, but this difference was not significant. We concluded that horses previously infected with and successfully treated for R equi-induced pneumonia do not have detectable evidence of residual lung damage.

Diaphragmatic herniation causing respiratory signs in a heifer.

A diaphragmatic hernia was found in a pre-partum dairy heifer that was exhibiting signs of respiratory disease. Ruminal tympany was included in the history although this was not a feature of the disease on admission. Diagnosis was made by auscultation and confirmed by radiology and during elective Caesarean section to remove the fetus.

Clinical manifestations of leukocyte adhesion deficiency in cattle: 14 cases (1977-1991).

In Holstein cattle, an inherited disease has been recognized recently in which leukocytes lack surface glycoproteins termed beta 2 integrins, which are important in cell adhesion processes. This disease is the homologue of leukocyte adhesion deficiency in human beings and has been termed bovine leukocyte adhesion deficiency. The molecular basis of this disease is failure to produce normal CD18. The gene encoding bovine CD18 and its abnormal mutation have been sequenced, allowing specific diagnosis of the condition by DNA amplification by polymerase chain reaction followed by specific endonuclease digestion. This test was applied to formalin-fixed archival tissues from 18 cattle that had been admitted to the veterinary medical teaching hospital between 1975 and 1991 and that had had persistent and severe neutrophilia. Blood samples were collected from 2 additional cattle, and leukocytes from these samples also were tested. Fourteen cattle were confirmed to have been homozygous for the bovine leukocyte adhesion deficiency gene. Cattle with this condition had ranged in age from 2 weeks to 8 months at admission. They typically had had chronic bacterial infections that had failed to respond to or had recurred after conventional treatment. Consistent findings in these cattle included signs of bronchopneumonia, gingivitis, periodontitis, and peripheral lymphadenopathy. Severe neutrophilia, usually without a left shift, was a hallmark of the disease; consistent clinical biochemical findings included hypoalbuminemia, hyperglobulinemia, and hypoglycemia. This disease is important because it mimics common calfhood diseases such as pneumonia and diarrhea, but is ultimately consistently fatal before adulthood.

Motor neuron degeneration in a horse.

A 9-year-old Quarter Horse mare was examined because of progressive weight loss, weakness, muscle atrophy and tremors, and behavioral change. Selenium and glutathione peroxidase assays, blood lead analysis, erythrocyte transketolase analysis, pseudorabies and Borrelia burgdorferi serology, electromyography, and CSF analysis were performed. Motor neuron degeneration was diagnosed by microscopic examination of neural tissues. The cause of the disease was not substantiated, but several possibilities were excluded via diagnostic testing. Diagnosis of motor neuron degeneration in horses may be made from an accurate history, thorough neurologic examination, and ancillary testing. In particular, antemortem diagnosis may be based on finding scattered angular atrophy of predominantly type-1 or of type-1 and -2 skeletal muscle fibers in frozen sections of muscle biopsy specimens.

Oropharyngeal abscessation in two cows secondary to administration of an oral calcium preparation.

This paper describes two cases of infection of the soft palate and pharyngeal wall in cattle. The infections were secondary to trauma and laceration received during treatment with an oral calcium preparation which was given to treat post-parturient hypocalcemia. Clinical signs included dehydration, depression, pseudoptyalism, and fetid breath. Other signs involved the upper respiratory and gastrointestinal tracts. Digital oral examination revealed the traumatized regions. Treatment included antibiotics and non-steroidal antiinflammatory agents. A semipermanent rumenostomy was performed on one cow for fluid and nutritional maintenance, but she died from secondary septic peritonitis. The second cow survived.

Retinal and optic nerve diseases.

Basic knowledge of the normal appearance and variations of the equine fundus coupled with frequent practice in ophthalmology will allow equine practitioners to be confident when assessing the equine fundus during ophthalmic examinations. Once the normal variations are mastered, appreciation of retinal, choroidal, optic nerve, and vitreal abnormalities is possible. Congenital and acquired lesions of the equine retina, optic nerve, and vitreous are discussed and illustrated.

Selective IgM deficiency and abnormal B-cell response in a foal.

Selective IgM deficiency was diagnosed in a 3-month-old Standardbred colt that was referred for chronic respiratory tract disease. Immunoglobulin quantification revealed normal IgG and IgA concentrations, but undetectable IgM concentration. Stimulation of blood lymphocytes with the T-cell mitogens concanavalin A and phytohemagglutinin yielded results within the normal range. However, stimulation with the B-cell mitogen lipopolysaccharide produced no response. A B-cell defect similar to that associated with several immunodeficiency disorders in people was suggested as the cause of the IgM deficiency in this colt.