Graft-versus-host disease in two immunocompetent dogs.

Graft-versus-host disease developed in two dogs injected with lymphocytes from BCG immunized donors. The disease was characterized by bone marrow depression, ulcerative enteritis, necrotizing cholangiohepatitis, thymic atrophy, pancreatitis, lymphadenopathy, inflammation of mucous membranes and weight loss. In one of the two dogs repopulation of bone marrow and lymphoid tissue by donor cells was demonstrated by cytogenetics. The development of GVHD was considered unusual because both animals received on immunosuppressive treatment and both responded well to PHA in lymphocyte transformation assays indicating they were immunocompetent. It was hypothesized that stimulation of donor lymphocytes by BCG enhanced their ability to induce a graft-versus-host reaction.

Neosporosis-like abortions in a herd of dairy cattle.

Twenty-nine cows from a 240-cow drylot Holstein dairy in north-central New Mexico aborted over a period of approximately 5 months. Nine aborted fetuses were necropsied, and all but 1 of the fetuses were between 5 and 7 months of gestation. Microscopic examination of fetal tissues revealed focal necrotizing encephalitis and nonsuppurative myocarditis in 7 of the 9 fetuses. Additional lesions observed in some fetuses were focal hepatic necrosis, nonsuppurative myositis, focal necrotizing placentitis, focal nonsuppurative pneumonia, and focal nonsuppurative nephritis. A few groups of Neospora caninum-like protozoan organisms were observed adjacent to necrotic foci in the brain of 2 fetuses and in the kidney of a third fetus. No other cause of abortion was detected.

Selenium toxicity in breeding ring-necked pheasants (Phasianus colchicus).

A flock of breeding ring-necked pheasants received feed with a high selenium content. Within 4 days of eating the toxic feed, the rate of egg production began to decrease, and bird aggression increased. Approximately 12% of the hens died within a week. Necropsy of the hens revealed colorless fluid around the heart and a friable, but otherwise normal, liver. The rapid onset of the problem and signs noted at necropsy suggested toxicosis. Based on analysis, the feed contained 9.3 ppm of selenium. Selenium toxicity was consistent with the histologic diagnosis of degenerative cardiomyopathy, vacuolar degeneration of hepatocytes, and centrilobular hepatic necrosis. After 8 days, the toxic feed was removed and replaced with fresh feed. Egg production, which had dropped to 50%, returned to normal within 10 days of feed replacement. Hatchability of eggs laid from days 8 to 14 after delivery of the toxic feed was 35%. Approximately 10% of the chicks that hatched had deformed beaks and abnormal eyes. Many of the chicks that died in the shell had deformities, bringing the total to more than 50% of all embryos that developed. The selenium content of eggs that had no embryonic development was 2.05 ppm. Hatchability of eggs laid from days 21 to 28 after the toxic feed was delivered was almost 80%, which was slightly lower than normal. The selenium content of these eggs was 0.30 ppm. These results show the rapid onset and correction of selenium toxicity and suggest that specific embryologic defects are diagnostic for selenium toxicity.

Embryonic mortality in Sprague-Dawley rats induced by snakeweed (Gutierrezia microcephala).

Three experiments were conducted to determine the effects of ingested snakeweed foliage (SW) on gestating rat embryos. Mature female Sprague-Dawley rats were paired with male rats and after breeding were randomly allotted to diets containing up to 15% SW. Feeding SW caused a decrease (P < .01) in the percentage of live embryos and markedly increased (P < .01) the percentage of dead or resorbed embryos. Snakeweed decreased (P < .01) feed intake in a dose-dependent manner and caused BW loss (P < .01) compared with control animals. However, decreased feed intake had no effect on gestating embryos. Rats fed the control diet, with intakes restricted to equal the average intake of rats fed SW, and those with ad libitum access to the control diet had similar percentages of live and dead embryos (P > .10). Serum clinical profiles reflected undernutrition (decreased triglycerides and cholesterol; P < .01) and mild toxicosis (elevated blood urea nitrogen, creatinine, and bilirubin; P < .01). Because fluid accumulation was noted in the uterus of several rats fed SW, a uterine weight bioassay was conducted. Snakeweed, fed as 10% of the total diet, decreased (P < .01) uterine weight of immature Sprague-Dawley rats. Ingestion of SW during early gestation caused embryonic mortality that could not be attributed to undernutrition or estrogenicity.

Lymphocyte transformation in the dog: response of lymphocytes from normal and immune dogs to phytohemagglutinin, coccidioidin, and purified-protein derivative.

Antigen- and mitogen-induced in vitro transformation of dog lymphocytes was quantitated by pulse labeling with 3H-thymidine (3H-TdR). Dosages of antigen and duration of incubation were varied to determine the dose and incubation time that would allow a clear distinction between sensitized and nonsensitized dogs. Each of the 2 antigens tested, coccidioidin and purified protein derivative of tuberculin, induced a higher rate of 3H-TdR incorporation in lymphocyte cultures from dogs immunized to the homologous antigen than in lymphocyte cultures from dogs immunized to either the heterologous antigen or no antigen. Lymphocyte cultures from all dogs showed a high rate of 3H-TdR incorporation in response to phytohemagglutinin stimulation. Sequential lymphocyte transformation tests were done on 4 dogs immunized with either Calmette-Guérin bacillus alone or Calmette-Guérin bacillus in Freund's complete adjuvant. A positive response to purified protein derivative became evident in all 4 dogs 11 days after immunization and peaked at 18 days after immunization.

Delayed cutaneous hypersensitivity in the dog: reaction to tuberculin purified protein derivative and coccidioidin.

A quantitative skin test for delayed-type hypersensitivity was developed in the dog. The test procedure involved testing animals in the pinna of the ear and quantitating the reaction by measuring the change in ear thickness. Skin test reactions to tuberculin-purified protein derivative and coccidioidin were found to be specific and to correlate with the immunization histories of the 27 dogs tested. Kinetic studies on the tuberculin reaction indicated that ear thickness increased slowly following antigen injection, reaching a peak at about 48 hours. Cellular infiltrates at reaction sites were primarily responsible for the increase in ear thickness. They consisted predominantly of mononuclear cells, although a marked number of neutrophils were also present. Multiple skin tests with tuberculin-purified protein derivative and coccidioidin on 8 nonimmunized (normal) dogs indicated that a skin test was capable of actively sensitizing a portion of the animals tested.

Correlation of in vitro and in vivo tests for cell-mediated immunity in the dog.

Using tuberculin (purified protein derivative) as the test antigen, 29 dogs with different vaccination histories were tested with the lymphocyte transformation (LT) assay, the indirect agarose leukocyte migration inhibition (LMI) assay, and the skin test for delayed type hypersensitivity. All three tests were done simultaneously on each dog. The LT assay results were found to correlate well (r = 0.88) with the skin test results, whereas LMI results were found to correlate poorly (r = 0.55) with the skin test results. It was concluded that the LT assay is a more reliable measure of cell mediated immunity in the dog than is the LMI assay.

Ovine caseous lymphadenitis: disease prevalence, lesion distribution, and thoracic manifestations in a population of mature culled sheep from western United States.

The prevalence, distribution, and severity of caseous lymphadenitis (CLA) lesions in 4,089 mature culled sheep were determined from a sample obtained by random selection of animal lots from a total population of 37,383 animals presented at an abattoir. The animals originated from 5 geographic regions comprising 9 western states. The prevalence rate for all forms of CLA was 42.41%. The prevalence of CLA lesions was significantly different in animals originating from 2 regions than it was in animals from the other 3 regions. The results indicate that CLA is a disease affecting a considerable number of mature culled sheep in different regions of western United States. Lesion distribution was catalogued according to a 4-compartment system: thoracic lymph nodes, lung parenchyma, abdominal tissues, and skeletal tissues including peripheral lymphatic tissues. Prevalence rates were determined for lesions occurring in the thoracic viscera (24.97%), skeletal tissues (23.09%), and abdominal viscera (11.79%). The prevalences of thoracic CLA lesions were significantly different for animals originating from 2 regions than for animals originating from the 3 other regions. Severe or advanced lesions were observed in the thoracic (3.74%) and abdominal viscera (1.27%). Involvements of CLA in the thoracic cavity occurred as abscesses of lung parenchyma, thoracic lymph nodes, or both. The bronchial and mediastinal lymph nodes were the most frequently affected thoracic lymph nodes. The liver was the most frequently affected abdominal organ, with the kidney being the next most commonly affected. The gross and histopathologic characteristics of CLA abscesses and tissues adjacent to the lesions were described.

Comparison of four serotests for the detection of Dirofilaria immitis infection in dogs.

Three hundred two dogs were tested with 4 serotests for heartworm antigen (AG) or antibody (AB) and with the Knott test. The 4 serotests evaluated were an enzyme-linked immunosorbent assay (ELISA) for adult heartworm-specific AB (AB-ELISA), a quantitative, indirect immunofluorescent assay (IFA) for adult heartworm-specific AB (AB-IFA), an IFA test for microfilaria (MF)-specific AB (MF-IFA), and an ELISA for adult heartworm AG (AG-ELISA). The presence of heartworms was ascertained in all dogs by necropsy examination. Of 302 dogs, 20 (6.6%) had heartworms in the heart at necropsy. Of infected dogs, 9 (45%) had occult infections. Test sensitivities were 75%, 95%, 70%, and 75% for the AB-ELISA, AB-IFA, MF-IFA, and AG-ELISA, respectively. Test specificities were 85% (AB-ELISA), 77% (AB-IFA), 87% (MF-IFA), and 99% (AG-ELISA). The best agreement between serotest results and necropsy findings was obtained with the AG-ELISA (97%). The 4 serotests detected 86% (AB-ELISA), 100% (AB-IFA), 67% (MF-IFA), and 78% (AG-ELISA) of the dogs with occult heartworm infection. A significant (P less than 0.05) association between intestinal parasitism and positive heartworm test results was found with only AB-IFA. Seemingly, the Knott test, or some other concentration method for detecting circulating MF should be the first heartworm test performed. If the examination for MF is negative, the dog has clinical signs, and radiographic findings are suggestive of occult heartworm infection, then a serotest for adult heartworm AG is recommended.

Experimental infection of lactating goats with Leptospira interrogans serovars pomona and hardjo.

Pathogenesis of Leptospira interrogans serovars pomona and hardjo was evaluated in 14 lactating goats. Although mild clinical signs of leptospiral infection characterized by pyrexia and reduction in milk yield appeared in some animals, a consistent clinical pattern was not observed in the inoculated animals. The pomona serovar was isolated from the kidney of 1 of the 4 goats inoculated with serovar pomona. The hardjo serovar (strain UI 750) was isolated in the rabbit serum-supplemented bovine albumin polysorbate-80 liquid medium only from the mammary gland of 1 of 4 goats at 13 days after inoculation with serovar hardjo. The positive culture was detected after an 8-month incubation period.

Elaeophorosis in bighorn sheep in New Mexico.

Two bighorn sheep (Ovis canadensis) in New Mexico (USA) were found to be naturally infected with Elaeophora schneideri. An adult ram examined in 1997 in the Fra Cristobal Mountains had 26 nematodes in the carotid and iliac arteries, and microfilariae were present in the skin, nasal mucosa, brain, and lungs. This ram was markedly debilitated prior to euthanasia and extensive crusty, scabby lesions were observed on its head. In 1998, a yearling ewe found dead adjacent to Watson Mountain near the Gila Wilderness area was found to have 13 nematodes present in its heart. This is the first report of E. schneideri in bighorn sheep, and we suggest that bighorn sheep are susceptible to E. schneideri infection wherever they coexist with mule deer (Odocoileus hemionus hemionus) and appropriate tabanid vectors.

Clinical, clinicopathologic, and pathologic features of plague in cats: 119 cases (1977-1988).

The clinical, clinicopathologic, and pathologic features of 119 cases of plague in cats from 1977 to 1988 in New Mexico were reviewed. Fifty-three percent were bubonic, 10% were pneumonic, 8% were septicemic, and 29% with neither buboes nor pneumonia were unclassified (but presumed septicemic). Three quarters of the lymphadenopathy was submandibular, and almost half of this was bilateral. One third of all cats had the triad of lethargy, anorexia, and fever in addition to buboes; one quarter had this triad plus abscesses. The overall mortality rate was 33%, with the greatest risk of death in pneumonic cases. For confirmatory diagnosis with a single laboratory test, fluorescent antibody was most frequently used (39% of cases). Cultures and passive hemagluttination titers were also used for confirmation. Gross and histologic findings depended on the type of plague, with Yersinia pestis organisms visualized in buboes of cats with bubonic plague and in the alveolar spaces and respiratory tubules of cats with pneumonic plague.

Feline plague in New Mexico: report of five cases.

Naturally acquired plague was diagnosed in 5 domestic cats. The cats apparently contracted the disease through contact with sylvatic rodents or their fleas in plague-enzootic areas. The diagnosis was confirmed by direct immunofluorescence and isolation of Yersinia pestis on culture of abscess material. Abscess formation, lymphadenitis, lethargy, and fever were consistent clinical findings.

Serologic survey for hantavirus infection in domestic animals and coyotes from New Mexico and northeastern Arizona.

OBJECTIVE: To determine whether animals had serologic evidence of infection with Sin Nombre virus (SNV). DESIGN: Prospective serosurvey. SAMPLE POPULATION: Serum samples were obtained from 145 cats, 85 dogs, 120 horses, and 24 cattle between April 1993 and August 1994 and 54 coyotes between December 1994 and February 1995. PROCEDURE: Serum samples were analyzed by western immunoblot assays for reaction with SNV nucleocapsid antigen. Samples with reactivity to SNV nucleocapsid proteins were used to probe multiple-antigen blots containing recombinant fusion proteins derived from prototypic hantaviruses. Lung tissue or blood clots were used in nested reverse-transcriptase polymerase chain reaction assays for a 320-nucleotide portion of the SNV G1 gene. RESULTS: Sera from 4 of 145 (2.8%) cats and 4 of 85 (3.5%) dogs had trace reactivity to full-length SNV-encoded nucleocapsid proteins. All samples from horses, cattle, and coyotes were nonreactive. Sera from cats and dogs that had trace IgG-antibody reactivity to nucleocapsid proteins were then tested for IgG-antibody reactivity to nucleocapsid proteins of prototypic hantaviruses. One cat had multiple cross-reactivities with these hantaviruses, consistent with exposure to a hantavirus; however, epitope mapping studies did not support this conclusion. Reverse-transcriptase polymerase chain reaction studies of blood clots or lung tissue from 2 animals that had weak reactivity to SNV failed to amplify any hantavirus sequence. CLINICAL IMPLICATIONS: Domestic animals, particularly dogs and cats, as well as coyotes do not appear to have a major role in the maintenance and transmission of SNV.

Effect of chronic ingestion of tarbush (Flourensia cernua) on ewe lambs.

Efforts to increase livestock utilization of tarbush are being coupled with studies to examine tarbush toxicity. Thirty-eight (19/treatment) ewe lambs were assigned at birth to receive either tarbush or alfalfa (15%, dry matter basis) in a sorghum-based growing ration. Lambs were pen-fed this diet 60 d pre-weaning and 60 d post-weaning. No differences existed between treatments in feed consumption. In the tarbush group, 1 lamb died of unknown causes at 90 d of age, while 3 lambs died between 115 and 120 d of age. There were no deaths in the alfalfa group. Shortly before death, lambs fed tarbush appeared lethargic, disoriented and anorectic. At 122 d of age, 5 lambs were randomly selected from each group. Feces and jugular blood samples were obtained from each lamb before being euthanized and necropsied the following day. All fecal samples were negative for occult blood. Serum gamma glutamyl-transpeptidase (P < 0.001) and aspartate aminotransferase (P < 0.001) activities and platelet counts (P < 0.05) were elevated in lambs fed tarbush, while serum calcium concentrations tended (P < 0.10) to be greater. Histologic examination revealed diffuse liver apoptosis in lambs fed tarbush. These data indicate tarbush leaves cause liver damage when fed for extended periods of time.

Pneumococcal sonicate-induced biphasic granulocytopenia and its dissociation from pulmonary leukostasis. The contribution of pneumococcal products and complement to early and late granulocytopenic phases.

The pathogenesis of pneumococcus (PNC)-induced granulocytopenia is unclear. We studied its relationship to pulmonary leukostasis and the possible roles of PNC constituents and complement. Nonviable PNC was infused into normal and 99% C3-depleted rabbits. PNC challenge induced both granulocytopenia and pulmonary leukostasis in normal animals; complement-depleted animals displayed granulocytopenia without pulmonary leukostasis. Therefore an intact complement system was not essential to the granulocytopenia, whereas pulmonary leukostasis was complement-dependent. Rabbits infused with serum, plasma, or nonpyrogenic normal saline, each after in vitro incubation with PNC, developed significant granulocytopenia (p less than 0.001, p less than 0.01, and p less than 0.001, respectively) with maximal mean percent decreases of -98%, -97%, and -91%, respectively. When the animals were sacrificed at 3 hr, no pulmonary leukostasis was found. The granulocytopenia persisted for 3 hr after infusion of either PNC-exposed serum or plasma, whereas the granulocytopenia induced by PNC-exposed saline was of less than or equal to 1 hr duration. If serum or plasma complement was inactivated prior to PNC incubation, subsequent infusion also induced significant granulocytopenia of less than 1 hr duration (p less than 0.05 and p less than 0.01). PNC-exposed saline that was subsequently heat-treated induced this same early (less than or equal to 1 hr) granulocytopenia (p less than 0.05). Control animals infused with serum, plasma, or saline unexposed to PNC displayed neither granulocytopenia nor pulmonary leukostasis. Therefore neither prior in vitro complement inactivation nor heat treatment after PNC incubation prevented the early granulocytopenic phase; in vitro complement inactivation totally aborted the late phase. The complement-independent, heat-stable early granulocytopenic phase was further investigated. Its granulocytopenia-inducing activity did not require the presence of PNC capsular polysaccharide and was resistant to trypsin treatment. With ultrafiltration, its molecular weight was 100,000 to 300,000. Thus PNC-induced granulocytopenia is a multifactorial phenomenon involving both complement-dependent and complement-independent mechanisms as well as contribution by PNC constituents or by-products.