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  • Colonic adenocarcinoma is a rare tumor of glandular crypt epithelium in middle-aged and older horses; the tumor may metastasize to the mesenteric lymph nodes, liver, and lungs, but it has not been reported to metastasize to bone and muscle.

  • Clinical signs of abdominal neoplasia may be vague and nonspecific; extensive diagnostic testing of these animals often is required.

  • Radionucleotide imaging, using technetium Tc 99m hydroxymethylene diphosphate in conjunction with technetium Tc 99m hexamethylpropylenamine oxime, can be a sensitive noninvasive tool to identify the nature of a disseminated disease when radiography is not sensitive enough to detect early osteoblastic changes that precede morphologic changes.

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in Journal of the American Veterinary Medical Association

Objective

To identify clinical signs, physical examination findings, results of diagnostic tests, treatments administered, and clinical outcome of neonatal foals with enterocolitis associated with Clostridium perfringens infection.

Design

Retrospective study.

Animals

54 neonatal foals.

Results

Most foals had acute onset of obtunded mentation, colic, or diarrhea and developed leukopenia, neutropenia, an abnormally high number of band neutrophils, toxic WBC, and hypoproteinemia within 24 hours after admission, despite high serum lgG concentrations (> 800 mg/dl). Abdominocentesis and abdominal radiography of some foals revealed exudative peritonitis and gaseous distention of the small and large intestine, respectively. Cytologic examination of feces revealed spores or gram-positive rods in 8 of 10 foals. The most common genotypes of C perfringens isolates were type A and C, alone or in combination. Treatment did not alter mortality rate for most foals that had a positive culture for C perfringens type C. Of 54 foals, 29 (54%) that had C perfringens-associated enterocolitis died. Foals that had a culture that yielded C perfringens had higher sepsis scores, IgG concentrations, and mortality rates, compared with the overall hospital population of neonatal foals.

Clinical Implications

Foals less than 7 days old that have enterocolitis associated with C perfringens infections, especially type C, have a guarded prognosis. Cytologic examination of feces to determine spore counts and detect rods may be a means for early identification of C perfringens infections. Polymerase chain reaction assays to determine genotype are important for designing preventive treatment regimens. (J Am Vet Med Assoc 1998;212:1751–1756)

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in Journal of the American Veterinary Medical Association

Objective

To determine the clinical manifestations, morbidity, mortality, and treatment methods for rattlesnake venom poisoning in horses.

Design

Retrospective analysis of medical records.

Animals

27 horses with acute venom poisoning attributable to prairie rattlesnakes, and 5 with chronic problems subsequent to a rattlesnake bite.

Results

Most horses were bitten on or near the muzzle while on pasture, resulting in head swelling, dyspnea, and epistaxis. Additional manifestations of acute poisoning included fever, tachycardia, tachypnea, cardiac arrhythmia, hemolytic anemia, thrombocytopenia, hemorrhage, thrombosis of venipuncture sites, colic, diarrhea, and prehensile and masticatory dysfunction. Chronic problems included cardiac disease, pneumonia, laminitis, pharyngeal paralysis, and wound complications. The most common chronic problem was cardiac disease. The most commonly used treatments were antibiotics, nonsteroidal anti-inflammatory drugs, tetanus prophylaxis, and airway support. Mortality in the 27 acutely affected horses was 18.5%; the overall mortality was 25%.

Clinical Implications

Horses bitten by prairie rattlesnakes may develop multiple, often severe, acute or chronic manifestations of poisoning involving various organ systems. Thorough clinical evaluation, effective treatment, supportive care, and close observation are indicated in horses with rattlesnake venom poisoning. (J Am Vet Med Assoc 1996;208:1866-1871)

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in Journal of the American Veterinary Medical Association

Summary

One hundred twenty-nine dogs with histologically confirmed malignant tumors were used in a prospective study to determine the toxicity of the new dihydroxyquinone derivative of anthracene, mitoxantrone, which was administered iv at 21-day intervals at dosages ranging from 2.5 to 5 mg/m2 body surface area. Each dog was evaluated for signs of toxicosis for 3 weeks after each dose was administered or until the dog died, whichever came first. The number of dogs in each evaluation period were as follows: 1 dose (n = 129), 2 doses (n = 82), 3 doses (n = 43), 4 doses (n = 26), 5 doses (n = 19), 6 doses (n = 9), 7 doses (n = 6), 8 doses (n = 5), 9 doses (n = 3), and 10 doses (n = 1). The most common signs of toxicosis were vomiting, diarrhea, anorexia, and sepsis secondary to myelosuppression. None of the dogs died of complications resulting from mitoxantrone treatment. Dogs with signs of toxicosis during the 21-day interval from administration of the first dose of mitoxantrone were 95 times (P = 0.003) more likely to develop signs of toxicosis during the 21-day interval from the second dose of mitoxantrone. Similarly, dogs that developed signs of toxicosis during the 21-day interval from the administration of the second dose were 34 times (P < 0.001) more likely to develop signs of toxicosis during the 21-day interval from the administration of the third dose. With each 1 mg/m2 increase in mitoxantrone, the odds of developing signs of toxicosis increased by 5.9 fold (P < 0.001). The performance status (modified Karnofsky performance scheme) of each dog was not adversely affected to a significant extent by mitoxantrone-induced toxicosis until the fifth dose (P = 0.0008). Cardiac toxicosis was not detected. Mitoxantrone was also administered iv to 4 clinically normal dogs, at a dosage of 5 mg/m2 of body surface area, a decrease in the neutrophil count was seen, with the nadir occurring on day 10 (mean ± sem: 1,159 ± 253 cells/μl; range, 480 to 1,680 cells/μl). Tumor-bearing dogs did not seem to have the same degree of myelosuppression (mean ± sem, 6,263 ± 1,230 cells/μl; range, 228 to 18,600 cells/μl).

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the percentage of broodmares and foals that shed Clostridium perfringens in their feces and classify the genotypes of those isolates.

Design—Prospective cross-sectional study.

Animals—128 broodmares and their foals on 6 equine premises.

Procedures—Anaerobic and aerobic bacteriologic cultures were performed on feces collected 3 times from broodmares and foals. All isolates of C perfringens were genotyped.

ResultsClostridium perfringens was isolated from the feces of 90% of 3-day-old foals and 64% of foals at 8 to 12 hours of age. A lower percentage of broodmares and 1- to 2-month-old foals shed C perfringens in their feces, compared with neonatal foals. Among samples with positive results, C perfringens type A was the most common genotype identified (85%); C perfringens type A with the β2 toxin gene was identified in 12% of samples, C perfringens type A with the enterotoxin gene was identified in 2.1% of samples, and C perfringens type C was identified in < 1% of samples.

Conclusions and Clinical RelevanceClostridium perfringens was identified from the feces of all but 6 foals by 3 days of age and is likely part of the normal microflora of neonatal foals. Most isolates from broodmares and foals are C perfringens type A; thus, the clinical relevance of culture results alone is questionable. Clostridium perfringens type C, which has been associated with neonatal enterocolitis, is rarely found in the feces of horses. (J Am Vet Med Assoc 2002;220:342–348)

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in Journal of the American Veterinary Medical Association