CAHFS Connection - November 2025

Avian

Predation was diagnosed in a 2-year-old hen with a history of being attacked 48 hours before death, followed by difficulty breathing. The most significant findings were hemorrhage in the neck and air sacs, suggestive of respiratory distress secondary to hemorrhage and trauma. Predation is a significant cause of death for free-range and backyard chickens, with predators including dogs, foxes, coyotes, raccoons, hawks, owls, weasels, and occasionally snakes.

Systemic amyloidosis and colibacillosis was identified in an 8-year-old male flamingo with a history of death following lethargy and watery feces of 1-day duration. The facility had previous cases of amyloidosis within their flamingo flock. Grossly, the kidneys were pale tan and covered by numerous white to tan, raised, 1 mm in diameter nodules. On histology, the majority of glomeruli were replaced by amyloid (Fig. 1), most likely causing renal dysfunction. Additionally, amyloid was identified within the lungs, spleen, adrenal glands, heart, and testicles. This bird also had intestinal and hepatic lesions suggestive of colibacillosis. Systemic amyloidosis is an important cause of death in domestic and captive wild birds. In flamingos, it is often reported in conjunction with chronic pododermatitis, although this was not observed in this case.

Figure 1. Global effacement of a single glomerulus by amyloid in the kidney of a flamingo. (A) Hematoxylin and eosin stain; (B) Congo red stain without polarization showing amyloid as bright red; and (C) Congo red stain with polarization highlighting amyloid as birefringent apple green.

Bovine

Tetralogy of Fallot and microphthalmos were diagnosed in fixed tissues from a field necropsy of a bovine fetus. The heart exhibited an interventricular septal defect, severe pulmonary artery stenosis, dextroposition of the aorta, and moderate dilation and hypertrophy of the right ventricle, findings consistent with tetralogy of Fallot. In addition, the animal had chronic hepatic congestion, microphthalmos, and, according to the submitter, cleft palate and arthrogryposis. In this case, PCR for bluetongue, bovine viral diarrhea, and border disease viruses were negative, and no further testing was performed. Other possible causes include: bunyaviruses, genetic defects, vitamin A deficiency, and exposure to teratogenic plants.

Leptospira pomona was the cause of abortion in two separate submissions of ~8-month gestation Holstein fetuses from different dairies. Both premises had experienced more than 20 abortions over the prior seven days, mainly in first calf heifers. The fetuses had mild to moderate icterus and nephritis. Leptospira PCR failed to detect the organism, but both cases were positive for Leptospira immunohistochemistry of the kidney. The dam sera from both premises had Leptospira pomona titers > 1:3,200. The heifers were not vaccinated for Leptospira.

Equine

Hemangiosarcoma was diagnosed on a spleenic biopsy from an 18-year-old Oldenburg gelding with a history of a splenic mass, and suspected metastasis to the body wall. On gross evaluation the mass was diffusely pale tan, slightly bulged on cut section, and was covered by a thin layer of tan and slightly filamentous material. On histology the neoplasm was composed of poorly differentiated mesenchymal cells that occasionally lined vascular channels. Based on these findings and positivity for Factor VIII immunohistochemistry, a diagnosis of hemangiosarcoma was established. Splenic tumors are rare in horses, and hemangiosarcoma and lymphoma are the most common neoplasms affecting this organ. These can be primary or metastatic.

Chronic dermatitis was diagnosed in a biopsy from a 21-year-old Quarter horse mare with a history of chronic alopecia in the white regions of all four socks. Pastern dermatitis was the top differential based on the history and signalment. Horses with white legs can often develop chronic dermatitis due to factors such as prolonged moisture exposure, allergens, mites, photosensitization, scratches, or chronic progressive lymphedema. A definitive diagnosis should be made based on a combination of both the pathology findings with the clinical presentation.

Pigs/Porcine

Mulberry heart disease was suspected in a 14-week-old gilt that died after a brief period of illness. The pig had marked hydropericardium, severe epicardial hemorrhages, pulmonary congestion and edema. Histologic exam of the heart revealed widespread hemorrhages with necrosis, myocarditis and arteriole degeneration consistent with mulberry heart disease. This disease in growing pigs is associated with Vitamin E and/or selenium deficiency. Selenium levels were adequate. Vitamin E analysis was not performed.

Small Ruminants

Tremetone toxicosis was implicated in the sudden death of a 2-month-old Alpine goat following a 3-day history of inappetence and lethargy. At least 11 goats in the herd were reported to have died suddenly. Toxicologists identified snakeroot (Ageratina altissima) (Fig. 2) on the premises prior to the necropsy submission. The most significant findings in this case were myocardial degeneration and necrosis. Gas chromatography-mass spectrometry on the plant identified the presence of tremetones, the primary toxic component of white snakeroot. White snakeroot is a poisonous plant that is indigenous to the eastern part of North America, but only rarely found in California. This plant causes skeletal and myocardial muscle in livestock. Clinical signs of poisoning include weight loss, listlessness, constipation, dyspnea, salivation, ketosis (characterized by acetone odor to the breath and urine), muscle tremors or violent trembling, tachycardia or other cardiac arrhythmias, and death.

Figure 2. (A) Snakeroot plant present on the property, (B) Heart showing multifocal areas of myofiber degeneration and necrosis, H&E.

Gastric squamous cell carcinoma was diagnosed in an 11-year-old, female alpaca with a history of chronic hyporexia and reduced water intake. There was a large, ulcerated mass involving the gastric C1 compartment that was diagnosed as a squamous cell carcinoma histologically. The mass had spread throughout the abdominal cavity lining, liver and lungs. Gastric squamous cell carcinomas in camelids have uncommonly been reported in the literature; extensive carcinomatosis of the abdominal cavity has been reported in at least one case.

Cervical stenosis and spinal cord compression resulted in pelvic limb weakness/ataxia and inability to breed in a yearling buck. Necropsy revealed cervical vertebral abnormalities in the body and articular facets of the third and fourth cervical vertebrae resulting in stenosis of the vertebral canal. Histologic examination of the spinal cord revealed severe axonal degeneration and loss consistent with chronic traumatic compressive myelopathy.