Cranioesophageal Pythiosis in a Horse

Background: Pythiosis is a chronic inflammatory disease that is caused by oomycete Pythium insidiosum. This illness affects several species including humans and horses. Equine is the most affected species, having no predisposition for breed, gender, or age. It is usually shown in cutaneous and subcutaneous forms, and the lesions, which grow quickly and are hard to treat, are located mainly in the extremities. The diagnosis is made via epidemiology, clinical signs, and macroscopic and microscopic aspects of the lesion. This study describes a case of cranioesophageal pythiosis in a horse, examining the epidemiological, clinical and pathological characteristics.Case: A 12-year-old male quarter horse, weighing 515 kg was taken to the Veterinary Hospital at the University Center of Espírito Santo (UNESC). The horse had an increase in volume in the cranioesophageal region, coughing, difficulty breathing, and a runny nose. On clinical examination, the horse showed an enlargement in the submandibular and retropharyngeal lymph nodes, subcutaneous edema in the larynx region, and a temperature of 38.2ºC. According to the owner, cough was recurrent and had lasted about 12 months even after treatment with different kinds of antimicrobials. On radiographic exam, there was a marked decrease in the tracheal lumen and increased soft tissue radiopacity in the region adjacent to the narrowing. The animal was taken to surgery to remove the mass, but he died because of complications during surgery. The animal’s owner did not allow necropsy, but a fragment of the mass in the cranioesophageal was removed and sent for histological examination. The fragment was fixed in 10% formalin and processed using routine histological analysis. Macroscopically, the mass was light yellowish and ulcerated, and it measured 7.0 × 5.0 × 5.0 cm. In the middle of the ulcerated areas, there were yellow and firm granular structures that were consistent with kunkers. Histologically, extending from the tracheal adventitia to the thyroid, there was a large number of lymphocytes, macrophages, neutrophils, eosinophils, and multinucleated cells (foreign body type) and a well-defined focus of coagulative necrosis, which was surrounded by a thin border of macrophages. Within the necrotic areas, there were negative images of tubuliform hyphae. Grocott’s silver methanamine staining showed hyphae that had irregular branches, rare septa, smooth and parallel walls, and was impregnated by silver. Histological sections of the mass were subjected to immunohistochemistry. Hyphae were positive for Pythium insidiosum.Discussion: The diagnosis of pythiosis was based on macroscopic, histological findings and positive immunostaining for Pythium insidiosum. This report shows the unusual location of the disease in the horse, which made the clinical diagnosis of the disease complex. Extracutaneous forms of pythiosis in horses are less frequent than cutaneous forms. The etiopathogenesis of these forms is still unclear, but it has been suggested that previous lesions in the intestinal mucosa caused by plant material or pathogens may be predisposing factors for the appearance of the enteric form of the disease. It was not possible to observe if the animal’s other organs were affected because a necropsy could not be performed. The agent probably penetrated the esophageal epithelium and spread throughout the trachea and thyroid, but its origin cannot be determined. The radiographic findings in this study are compatible with neoplasms. However, inflammatory processes such as those caused by pythiosis should be included in the differential diagnosis of horses with swelling in the cranial portion of the esophagus

Atypical Spleen Hemophagocytic Histiocytic Sarcoma in a Dog

Background: The histiocytic sarcoma (HS) complex is a set of malignant neoplasms originating from interstitial dendritic cells or macrophages. When it involves macrophages of the splenic red pulp and bone marrow, it is referred to as hemophagocytic histiocytic sarcoma (HHS). HHS behaves more aggressively than HS and is usually fatal. HHS can be diagnosed by cytological and histopathological examination of neoplastic tissue. HHS is confirmed by immunohistochemistry using an anti-CD11d antibody. This neoplasm is often confused with immune-mediated hemolytic anemia or Evans syndrome due to erythrophagocytosis and platelet consumption. The clinical presentation of the animals progresses with evident anemia and thrombocytopenia, leading to signs such as prostration, inappetence, and pale mucosa, making diagnosis challenging and often late. This study aimed to report the clinic-pathological aspects of a canine with atypical hemophagocytic splenic HS.Case: A 4-year-old male Shih-Tzu canine was referred to the Veterinary Hospital with a history of prostration and anorexia. Pale mucous membranes were observed on physical examination. Blood tests revealed non-regenerative anemia, leukopenia, and thrombocytopenia. Serum protein levels were below the reference values for the species in biochemical examinations. Hemoparasitosis was suspected; however, the result of the polymerase chain reaction was negative. Abdominal ultrasound revealed a splenomegaly with heterogeneous parenchyma and a slightly irregular surface, but no visible mass in the spleen. Due to the difficulty of stabilizing the patient, even after successive transfusions, the animal underwent exploratory laparotomy with medial access and posterior splenectomy. Subsequently, the spleen was surgically removed, fixed in 10% buffered formalin, and processed routinely. Macroscopically, it had an irregular reddish-brown capsular surface. Histopathological examination of the spleen revealed a densely cellular neoplasm composed of round to spindle cells (histiocytes) arranged haphazardly in variably sized sheets separating the pre-existing spleen stroma. These histopathological findings were consistent with a histiocytic malignant neoplasm. Immunohistochemical analysis was performed to better define the origin of the histiocytic neoplasm. Neoplastic cells showed positive immunostaining of more than 80% of tumor cells for the CD11d antibody and weak immunostaining for CD11c and lysozyme. The patient survived for less than 30 days after the first hospital visit.Discussion: The diagnosis of HHS was based on the histological characteristics and positive immunostaining of more than 80% of the tumor cells for the CD11d antibody. HHS is an extremely aggressive and rare tumor that affects elderly dogs of any breed. In this study, HHS had atypical histologic characteristics, in which erythrophagocytosis and hemosiderin were not observed within macrophages. HHSs arise from macrophages of the red pulp of the spleen or bone marrow and express the b2 integrin, CD11d, and have low expression of CD1 and CD11c, which are predominantly expressed by non-hemophagocytic HS. The hematological and biochemical changes observed in this case were similar to those described in other dogs with HHS. Treatment of HHS is only palliative. Erlichia ewingii, E. canis, Anaplasma phagocytophilum, A. platys, Borrelia burgdorferi, Dirofilaria immitis, Leishmania infantum and immune-mediated hemolytic anemia are the main differential diagnoses because they cause anemia and thrombocytopenia accompanied by splenomegaly.Keywords: histiocytic sarcoma, spleen, immunohistochemistry, splenectomy, erythrophagocytosis

Multiple Metastases of a Transmissible Venereal Tumor in a Dog

Background: Transmissible venereal tumor (TVT) is a common contagious neoplasm in dogs that spreads through coitus. Extra-genital presentations of this tumor are frequent and usually develop through implantation of neoplastic cells on exposed mucosae. TVT metastasis is rare, and when it happens it’s usually affecting regional lymph nodes and adjacent cutaneous tissue.Case: A female mixed breed dog, with estimated age of 7 to 11-month-old, was rescued from the streets and taken to a veterinary clinic in the city of Porto Alegre, RS. The animal had multiple nodules on its body, vulva, ocular mucosa, and gingiva, along with signs of malnutrition and apathy. Cytological examination of the nodules and vulva was done and yielded a cytologic picture compatible with TVT.  Weakly treatment with 0.3 mg/m² vincristine sulphate was used until clinical cure was noted. Approximately two weeks after clinical cure, the dog showed a blue colored eye and was referred for ophthalmological, where it was diagnosed with vision loss due to glaucoma secondary to a neoplasm. The eye was then removed and sent for histopathological evaluation. Histopathology of the eye was compatible with TVT diagnosis. One month after enucleation the animal display dispenia, pain, aggressiveness and epistaxis. The animal was euthanized and submitted for post-mortem evaluation. At necropsy there was a well-defined grayish-white, nodule near the thalamus. Similar nodules were also found on the lung, and anterior chamber of the eye. Histologically, all the nodules were compatible with TVT. Immunohistochemical examination was done, with the neoplastic cells being positive for vimentin and negative for cytokeratin, CD79a, CD3 and CD117. Based on the post-mortem examination and clinical history, diagnosis of TVT was given.Discussion: The clinical manifestation of the tumor in the genitalia presented by the animal is characteristic of TVT, but the extragenital presentation is less common. Although extragenital manifestations are well reported, most are due to auto-implantation (contact with the dog’s own genitalia) or hetero-implantation (contact with the genitalia of another dog). Metastases originating from the genitalia are markedly less common (5% of cases), and when they occur, they usually affect regional lymph nodes due to lymphatic communication. However, they can also occur in other organs, such as the liver, kidneys, spleen, tonsils, skin and subcutaneous tissue, bone, CNS, mesentery, and eyes. In this case, it is difficult to determine if the ocular tumor reported was due to metastasis or implantation by direct eye contact with TVT cells, since the animal lived on the street, and it was not possible to establish a more accurate history. The dog in this study was treated with vincristine sulfate; however, the treatment was stopped after one month, when no signs of the tumor were observed. Treatment with vincristine is the method of choice for TVT, since it is highly effective. However, rare cases of recurrence after treatment may occur. In addition, this drug does not cross the blood-brain barrier, and this may have favored the rapid reappearance of the tumor after treatment. The metastases from TVT to the CNS are extremely rare, with only a few cases reported in the literature. However, the possibility of metastases in animals with neurological and historical signs of TVT should be considered in the diagnosis. This case draws attention to the occurrence of TVT in the CNS of dogs with ocular TVT

Pentalogy of Fallot in a Crioulo Foal

Background: Cardiac anomalies account for 3.5% of congenital defects in horses. Tetralogy of Fallot (TOF) is characterized by ventricular septal defect, pulmonary stenosis, dextroposition the aorta and right ventricular hypertrophy secondary.Pentalogy of Fallot (POF) is a variation and is characterized by a defect in the right atrioventricular valve or persistence of the ductus arteriosus, in addition to the other defects observed in tetralogy. Affected animals usually have stunted growth,exercise intolerance, weakness, lethargy, cyanosis, dyspnea and syncope. The aim of this study was to describe a case of POF, as diagnosed in a Crioulo foal in southern Brazil.Case: Clinical signs were observed at the ffth day of life and were characterized by cyanosis, intense tracheal stertor, tachycardia, marked heart murmur, HR 160 bpm, RR 80 breaths/min, T 39.8°C and syncope. These signs worsened with physical activity. Endoscopic evaluation of the upper airways revealed no anatomical conformation changes or tissue dysfunction. A cardiac ultrasound showed a loss of continuity of the interventricular septum, right ventricular wall thickening, and a hyperechoic appearance of the area where the right atrioventricular valve (tricuspid) should be. The crises have become more severe and more frequent, the animal began to show signs of ischemia, such as loss of motor coordination and limited mobility. The foal died at 15 days old. At necropsy the liver was congested and had a nutmeg appearance, there was foam in the trachea, and the lungs were edematous. There was hydropericardium, and the heart was increased in size with a globoid shape. The heart had thickening of the walls of the right and left ventricle and pulmonary artery stenosis. There was also an oval orifce 2.5 cm in diameter in the interventricular septum connecting the ventricles (ventricular septal defect), an overriding aorta and aplasia of the tricuspid valve. Histologically the liver had centrilobular to mediozonal necrosis, and there was pulmonary edema and congestion.Discussion: The diagnosis of pentalogy of Fallot was based on the clinical signs, the ultrasound results and the macroscopic lesions observed at necropsy. Tetralogy of Fallot is one of the most common congenital cardiac malformations observed in horses, however, in a study of congenital malformations in this species, only 3.5% had cardiac malformations out ofthe 608 foals examined. The prevalence of heart defects in horses compared with other domestic species is relatively low (0.1% - 0.5%). In this case, the malformation was probably sporadic because the foal was the only animal to be born with this malformation on the farm. In the Crioulo breed, congenital defect reports are scarce. In a retrospective study of equine diseases in southern Brazil over a period of 35 years, malformations were not observed in 708 horses of this breed, whichis the predominant breed in the region. In the present case, the fact that the mare had another three healthy foals with the same stallion reduces the possibility that this was a case of hereditary origin. It is likely that this case is of a sporadic nature with no chance of determining the cause. The differential diagnoses in animals with lethargy, cyanosis, and exerciseintolerance or syncope include complicated or multiple cardiac defects. There are no previous reports of TOF and POF in the Crioulo breed in Brazil.Keywords: Pentalogia de Fallot, cardiac ultrasound, cardiac malformation, horse

Equine poisoning by coffee husk (Coffea canephora) in northern Espírito Santo, Brazil

Background: Brazil is the largest coffee (Coffea canephora) producer in the world, and Espírito Santo state is the second largest national producer of this commodity. Caffeine poisoning has been described in several animal and human species and is generally associated with accidental and/or intentional ingestion of caffeine-containing products. In horses, there are few reports in the literature about coffee poisoning, and most animals show clinical signs of excitability, involuntary muscle tremors, and chewing movements. Therefore, the objectives of the present study are to describe the clinical and epidemiological aspects of coffee (Coffea canephora) poisoning in horses in northern Espírito Santo, Brazil.Cases: Two horses from northern Espírito Santo presented with clinical signs of excessive sweating, reluctance to enter the trailer, muscle tremors, aggression, incoordination, constant tremors of the lips and tongue, chewing movements, and falling. Clinical signs began after the animals were confined in stalls containing coffee husk (Coffea canephora) for at least one week. After three days in the stall, the horse began to show clinical signs characterized by excessive sweating, reluctance to enter the trailer, aggression, and incoordination. On physical examination, there was marked dehydration, tachycardia (120 bpm), tachypnea (80 mpm) and a body temperature of 39.1ºC. In addition, the animal had cecum and ventral colon hypomotility. The horse was treated as soon as it was admitted to the hospital with a 10 mL / h intravenous drip of Ringer lactate solution; 100 mL intravenous mercepton every 24 h; 10 mL intramuscular vitamin B1 every 24 h, and 1.1 mL intravenous acepromazine 1%; when it showed increased excitability, it was treated for neurological signs and recovered four days after admission. The second animal was a 3-year-old female Mangalarga Marchador horse, weighing 280 kg. The animal was confined for 30 days with coffee husk bedding. The horse was fed 8 kg of corn silage and 4 kg of granulated feed per day. After two weeks in confinement, the animal began to show severe incoordination, extremely aggressive behavior, muscle tremors, constant tremors of the lips and tongue, chewing movements, excessive sweating, and falling.Discussion: The diagnosis of coffee husk poisoning was based on the epidemiological and clinical characteristics of the disease. In Espírito Santo, it seems to be common to use coffee husk as bedding material for horses, mostly as a substitute for sand and wood shavings. In the properties where the animals lived, the coffee was planted to sell, and the remains from production, especially the husks, were used as bedding for the animals. It has been reported that when horses are placed in stalls with coffee husks, they tend to eat the husks spontaneously, resulting in intoxication. The clinical signs observed in this study were similar to those described in horses experimentally intoxicated by the plant. The neurological effects observed were due to the action of caffeine as an adenosine antagonist. The observed neurological clinical signs observed in these cases were nonspecific, and other disorders of the equine central nervous system, such as rabies and leukoencephalomalacia, should be considered in the differential diagnosis of coffee poisoning. Coffee husks should not be used as bedding for horses, as it can cause animal poisoning and death due to the excitatory effects of caffeine, which can lead to spontaneous falls and serious trauma

Aprosopia/holoprosencephaly in a stillborn puppy: when the face predicts the brain

In a litter of three puppies, one was stillborn and had facial and brain defects. Fusion of the maxilla and mandible and absence of the face were observed. The forebrain (telencephalon and the diencephalon) was reduced in size and fused, and the telencephalic longitudinal fissure, olfactory bulbs, and optic nerves were absent (Figures 6 and 7). Lissencephaly was observed in the telencephalon and cerebellum. A diagnosis of aprosopia/holoprosencephaly was made

Solid Iridociliary Carcinoma in a Dog

Background: Iridociliary epithelial tumors (ICETs) originate from the iris epithelium or ciliary body. They comprise ciliary body adenoma, carcinoma, pleomorphic adenocarcinomas, medulloepitheliomas, and other primitive neuroectodermal tumors. They are the second most common primary intraocular tumors in dogs and have already been reported in sheep and humans. In dogs, they occur more frequently in middle-aged to elderly animals, and the Labrador and Golden Retriever seem to be more predisposed breeds. This study aimed to describe the clinical and pathological aspects of solid iridociliary carcinoma in a dog. Case: A 3-year-old Poodle bitch was treated for discomfort in the left eyeball region, increased intraocular pressure and moderate buphthalmia. A direct ophthalmological examination was performed without equipment, and a mass was visualized in the posterior chamber, distorting the pupillary cleft. We opted for unilateral enucleation and forwarded the material for histological analysis. Macroscopically, the eyeball measured 3.4 cm (anteroposterior) x 2.6 cm (vertical), with a brownish mass that occupied the entire anterior chamber and part of the posterior chamber. Histologically, there was a neoformation in the ciliary body and iris pigment epithelium, partially well-delimited and densely cellular. The neoplasm was organized into predominantly solid formations interspersed with a discrete amount of blood vessels, rare bundles of fibrous stroma, and amorphous eosinophilic material forming membranes that were positive for PAS. Sections of the neoplasm were subjected to immunohistochemistry using anti-cytokeratin AE1/AE3, anti-S100 protein, anti-vimentin, and anti-Ki-67. Positive cytoplasmic immunostaining for cytokeratin and S-100 was observed. Only 45.6% of cells were positive for Ki-67 (500 cells). No immunostaining was observed for vimentin. Discussion: The diagnosis of solid iridociliary carcinoma was based on the histological features and positive immunostaining for cytokeratin AE1/AE3 and protein S100. Iridociliary carcinomas present positive immunostaining for cytokeratin, whereas adenomas and normal iridociliary epithelium do not present this immunostaining. Moreover, the high rate of cell proliferation was indicative of malignant neoplasia, as observed by the high mitotic count and high positivity for Ki-67. The S100 protein helped in the diagnosis of ICETs, as the iridociliary epithelium showed positive staining for this protein. Some histological features are important to consider in the diagnosis of iridociliary tumors in dogs, such as noninvasive growth in the posterior chamber, pigment epithelium, and thick homogeneous membranes on the cell surface. Furthermore, the presence of positive PAS membranes favors the diagnosis of iridociliary epithelial tumors. ICETs must be differentiated from melanocytomas, anterior uveal melanoma, medulloepitheliomas, and metastatic and pleomorphic carcinomas. The histological characteristics, especially the presence of PAS-positive membranes, associated with the immunohistochemical profile of neoplasm cells, help differentiate the ICETs from these tumors. In general, the prognosis is poor for eyeball and vision maintenance in canine iridociliary tumors, and scleral invasion is associated with a higher recurrence rate.   Keywords: neoplasm, eye, immunohistochemistry, cytokeratin, S100 protein