Systemic Amyloid A Amyloidosis in Island Foxes (Urocyon littoralis): Severity and Risk Factors.

Systemic amyloid A (AA) amyloidosis is highly prevalent (34%) in endangered island foxes (Urocyon littoralis) and poses a risk to species recovery. Although elevated serum AA (SAA) from prolonged or recurrent inflammation predisposes to AA amyloidosis, additional risk factors are poorly understood. Here we define the severity of glomerular and medullary renal amyloid and identify risk factors for AA amyloidosis in 321 island foxes necropsied from 1987 through 2010. In affected kidneys, amyloid more commonly accumulated in the medullary interstitium than in the glomeruli (98% [n= 78 of 80] vs 56% [n= 45], respectively;P< .0001), and medullary deposition was more commonly severe (19% [n= 20 of 105]) as compared with glomeruli (7% [n= 7];P= .01). Univariate odds ratios (ORs) of severe renal AA amyloidosis were greater for short- and long-term captive foxes as compared with free-ranging foxes (ORs = 3.2, 3.7, respectively; overall P= .05) and for females as compared with males (OR = 2.9;P= .05). Multivariable logistic regression revealed that independent risk factors for amyloid development were increasing age class (OR = 3.8;P< .0001), San Clemente Island subspecies versus San Nicolas Island subspecies (OR = 5.3;P= .0003), captivity (OR = 5.1;P= .0001), and nephritis (OR = 2.3;P= .01). The increased risk associated with the San Clemente subspecies or captivity suggests roles for genetic as well as exogenous risk factors in the development of AA amyloidosis.

Experimental chronic wasting disease (CWD) in the ferret.

Chronic wasting disease (CWD), a prion disease of North American deer, elk and moose, affects both free-ranging and captive cervids. The potential host range for CWD remains uncertain. The susceptibility of the ferret to CWD was examined experimentally by administering infectious brain material by the intracerebral (IC) or oral (PO) route. Between 15 and 20 months after IC inoculation, ferrets developed neurological signs consistent with prion disease, including polyphagia, somnolence, piloerection, lordosis and ataxia. Upon first sub-passage of ferret-adapted CWD, the incubation period decreased to 5 months. Spongiform change in the neuropil was most marked in the basal ganglia, thalamus, midbrain and pons. The deposition of PrP(CWD) was granular and was occasionally closely associated with, or localized within, neurons. There were no plaque-like or perivascular PrP aggregates as seen in CWD-infected cervids. In western blots, the PrP(CWD) glycoform profile resembled that of CWD in deer, typified by a dominant diglycosylated glycoform. CWD disease in ferrets followed IC but not PO inoculation, even after 31 months of observation. These findings indicate that CWD-infected ferrets share microscopical and biochemical features of CWD in cervids, but appear to be relatively resistant to oral infection by primary CWD inoculum of deer origin.

Association of excess sulfur intake and an increase in hydrogen sulfide concentrations in the ruminal gas cap of recently weaned beef calves with polioencephalomalacia.

During a 2-week period, 16 of 150 recently weaned calves developed signs of polioencephalomalacia (PEM). One calf was examined and treated at our veterinary teaching hospital and a necropsy was performed on a calf that died. During the peak of the outbreak, clinicians visited the ranch. Ruminal hydrogen sulfide (H2S) and blood thiamine concentrations were measured in 10 clinically normal penmates of PEM-affected calves. Ruminal H2S concentrations were high (> 0.695 mg/L [> 500 ppm]) in all cattle (mean, 12.19 mg/L [8,770 ppm]). All blood thiamine values were within the reference range. Within 12 hours after measurement of blood thiamine concentrations, 2 of the calves from which samples were obtained developed clinical signs of PEM. Dietary analysis revealed an estimated sulfur intake of 0.9% per calf on a dry-matter basis. Hay contributed most of this sulfur. In the investigation reported here, an outbreak of PEM was associated with high ruminal H2S concentrations and excess sulfur intake without evidence of thiamine deficiency.

Globoid cell-like leukodystrophy in a domestic longhaired cat.

Globoid cell leukodystrophy (GLD; Krabbe disease), is a rare heritable metabolic disorder in humans, dogs, mutant twitcher mice, and rhesus monkeys that is caused by a deficiency in the lysosomal enzyme galactocerebrosidase (GALC). GALC deficiency results in the accumulation of psychosine, which is toxic to oligodendrocytes and Schwann cells of the central and peripheral nervous systems. Clinical signs include hypotonia, mental regression, and death by 2 years of age in most human patients. Here we describe a domestic longhaired kitten with rapidly progressive neurologic disease and brain and spinal cord lesions characteristic of GLD. Pathologic hallmarks of the disease reflect the loss of oligodendrocytes and include myelin loss, gliosis, and the perivascular accumulation of large mononuclear cells with fine cytoplasmic vacuoles (globoid cells) in the peripheral and central nervous systems. Globoid cells were CD68 and ferritin positive, confirming their monocytic origin, and cytoplasmic contents were nonmetachromatic and periodic acid-Schiff positive.

Distribution of protease-resistant prion protein and spongiform encephalopathy in free-ranging mule deer (Odocoileus hemionus) with chronic wasting disease.

Serial sections of brain and palatine tonsil were examined by immunohistochemical staining (IHC) using monoclonal antibody F89/160.1.5 for detecting protease-resistant prion protein (PrP(res)) in 35 hunter-killed mule deer (Odocoileus hemionus) with chronic wasting disease. Serial sections of brain were stained with hematoxylin and eosin and examined for spongiform encephalopathy (SE). Clinical signs of disease were not observed in any of these deer. On the basis of the location and abundance of IHC and the location and severity of SE, deer were placed into four categories. Category 1 (n = 8) was characterized by IHC in the palatine tonsil with no evidence of IHC or SE in the brain. Category 2 (n = 13) was characterized by IHC in the palatine tonsil and IHC with or without SE in the dorsal motor nucleus of the vagus nerve (DMNV). Category 3 (n = 2) was characterized by IHC in the palatine tonsil, IHC with SE in the myelencephalon, and IHC without SE in the hypothalamus. Category 4 (n = 12) was characterized by IHC in the palatine tonsil and IHC with SE throughout the brain. Category I may represent early lymphoid tissue localization of PrP(res). The DMNV appears to be the most consistent single neuroanatomic site of detectable PrP(res). Categories 2-4 may represent a progression of spread of PrP(res) and SE throughout the brain. IHC in tonsil and brain and SE in brain were not detected in 208 control deer.