AFIP Wednesday Slide Conference - No. 22

April 02 1997
Conference Moderator: Dr. Yvonne Schulman
Diplomate, ACVP
Department of Veterinary Pathology
Armed Forces Institute of Pathology
Washington DC 20306-6000
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Case I - 182690 (AFIP 2547361), 2 photos

Signalment: 6-year-old, male, military macaw (Ara militaris ).
History: This bird was behaving normally and eating up to the time of death and had been exposed to a conure that died with non-specific signs. The prior medical history included a cloacal prolapse while a juvenile. The clinical differential diagnosis case included Pacheco's disease, psittacosis and tuberculosis.
Gross Pathology: The carcass was moderately emaciated. Foul mucoid fluid filled the crop and the entire upper esophagus was filled with soft grey-pink confluent papillated masses that were pedunculated on thin vascular stalks from the mucosa. These impinged upon the lumen but the esophageal wall was normal and there was an abrupt transition into the normal lower esophagus. Similar soft white sessile nodules up to 4mm in diameter were collected around the choana and base of the tongue. The proventriculus was adherent to the massively enlarged left liver lobe and both lobes had multiple confluent yellow-white nodules up to 20mm in diameter, especially concentrated along the outer margins. The skin, cloaca and remainder of the digestive tract of this bird were normal, as were all other organ systems.
Laboratory Results: Previous blood work and culture yielded no specific findings and impression smears from liver, spleen and air sac were negative for chlamydia.

Contributor's Diagnosis and Comments:
1. Oropharyngeal and esophageal papillomatosis.
2. Cholangiocarcinoma
Etiology - Undetermined
Samples taken from several areas of the papillomatous mucosal proliferations demonstrated similar benign features with no evidence of malignant transformation.
Papillomas of the skin and digestive tract have been reported in a large variety of psittacine species. Cloacal papillomas are quite common, especially in Amazon parrots, and there are reports of concurrent bile duct carcinomas. A viral origin has been assumed but so far a papillomavirus has been isolated only in chaffinches, bramblings and a Timneh African grey parrot. Herpes-like virus particles were seen in a cloacal papilloma of an orange-fronted conure.
The present case is somewhat unusual in that there was no cloacal involvement, although no tissue was examined at the time of the cloacal prolapse. There are reports of spontaneous regression of these tumors. These papillomas have been found in macaws, with a recent paper documenting associated pancreatic and intestinal adenocarcinomas. Cholangiocarcinoma is reportedly the most frequent hepatic tumor in captive and free-ranging birds (other than lymphoma in gallinaceous species). Malignant transformation from viral infection has not been suggested yet.
AFIP Diagnosis:
1. Liver: Cholangiocarcinoma, military macaw (Ara militaris), avian.
2. Oropharynx: Papilloma.
Conference Note: The participants agreed with the contributor's diagnoses and comments. Bile duct carcinomas have been associated with cloacal prolapse and with oropharyngeal and cloacal papillomas in macaws and Amazon parrots. The cause of this association is undetermined.
Contributor: Los Angeles County Veterinary Public Health, 313 North Figueroa St., Los Angeles, CA 90012.
1. Latimer KS: Oncology. In: Ritchie BW, Harrison GH, Harrison LR (eds.): Avian Medicine: Principles and Application. Wingers Publishing, Inc., pp. 655-658 1994.
2. Lach H: Viruses. In: Ibid; pp. 885-888.
3. Kennedy FA. Oropharyngeal and Cloacal Papillomas in 2 Macaws (Ara sp.). with a Pancreatic and an Intestinal Adencarcinoma with Hepatic Metastasis (abstract). Proceedings ACVP, 1995 in Vet Pathol 32:589, 1995.
4. Hillyer EV, Moroff S, Hoefer H, Quesenberry KE: Bile duct carcinoma in two out of ten Amazon parrots with cloacal papillomas. Avian Med 5(2):91-95, 1991.
5. Coleman CW: Bile duct carcinoma and cloacal prolapse in an Orange-winged Amazon parrot (Amazona amazonica amazonica). Avian Med 5(2):87-89, 1991.
International Veterinary Pathology Slide Bank:
Laser disk frame #10902, 11159, 11160, 2534, 2535, 2536, 11276, 14574, 18344, 20011.

Case II - 96-55892 (AFIP 2548594)

Signalment: Channel catfish (Ictalurus punctatus) fry.
History: High mortality was observed among the catfish several weeks following introduction into a "proliferative gill disease-free" pond.
Gross Pathology: Formalin-fixed tissues were submitted for evaluation.
Laboratory Results: None.
Contributor's Diagnosis and Comments: Gill: Branchitis, histiocytic and proliferative, diffuse, with intra-epithelial myxosporidian parasites, channel catfish (Ictalurus punctatus), piscine.
Proposed etiologic agent: Aurantiactinomyxon ictaluri.
Gill lamellae are diffusely thickened by a histiocytic infiltrate. Randomly scattered epithelial cells (host or mother cells) contain dense cytoplasmic aggregates of 1 m round basophilic bodies (developing spores). A small number of tissue sections also contain sections of an interlamellar metazoan parasite.
Proliferative gill disease (PGD) is an important disease of cultured channel catfish. Experimentally, it has been produced only by exposure of naive catfish to pond mud from "diseased ponds". The oligochaete Dero digitata is suspected of being an alternate host. PGD is most prevalent in newly-established ponds or in old ponds that have been drained and dried between harvesting and restocking. In these ponds, well- oxygenated water and abundant organic material provide ideal conditions for D. digitata. Efforts in controlling PGD have been centered on reducing the numbers of D. digitata by stocking these ponds with predators such as the flathead minnow, stocking with oligochaetes other than Dero spp., and altering characteristics of the pond bottom (organic matter content).
AFIP Diagnosis: Gill: Branchitis, proliferative and histiocytic, diffuse, moderate to severe, with protozoan spores, channel catfish (Ictalurus punctatus), piscine.
Conference Note: Proliferative gill disease (PGD) of channel catfish occurs throughout commercial catfish-producing regions of the United States, where it has caused severe economic losses to individual producers since 1981. The gills of affected fish become swollen and friable and may bleed when touched. Respiratory efficiency is reduced and the fish may gasp for air at dissolved oxygen concentrations that are normally adequate. Mortality may be chronic or sudden and massive.
PGD remains poorly understood despite being a major economic concern. Possible causative agents have included Henneguya exilis, Spaerospora ictaluri, and an unidentified myxozoan. Recent reports provide solid evidence that the causative agent of PGD is a myxozoan and a species of Aurantiactinomyxon (Actinomyxea; Triactinomyxidae).
Contributor: Veterinary Diagnostic & Investigational Lab, P.O. Box 1389, Tifton, GA 31793.
1. Bellerud BL, Pote LM, Lin TL, Johnson MJ, Boyle CR: Etiological and epizootiological factors associated with outbreaks of proliferative gill disease in channel catfish. Journal of Aquatic Animal Health 7:124-131, 1995.
2. Burtle GJ, Harrison LR, Styer EL: Detection of a triactinomyxid myxozoan in an oligochaete from ponds with proliferative gill disease in channel catfish. Journal of Aquatic Animal Health 3:281-287, 1991.
3. Styer EL, Harrison LR, Burtle GJ: In search of the cause of proliferative gill disease in channel catfish, Ictalurus punctatus: preliminary results of a two-year study. Journal of Applied Aquaculture 3:51-65, 1993.
4. Styer EL, Harrison LR, Burtle GJ: Experimental production of proliferative gill disease in channel cat fish exposed to a myxozoan-infected oligochaete, Dero digitata. Journal of Aquatic Animal Health 3:288-291, 1991.
5. Thune RL. Parasites of catfishes, In: Fish Medicine, Stoskopf MK ed., W.B. Saunders, pp. 524-526. 1993.
International Veterinary Pathology Slide Bank:
Laser disc frame #05455, 05456, 24426, 24240, 24241.

Case III - 34566 (AFIP 2548691), 2 photos

Signalment: 8 year old female feline, domestic shorthair.
History: Long history (years) of dyspnea, diagnosed as "feline asthma". Treated intermittently with aminophylline and prednisone. Presented with 2 day history of anorexia and vomiting. Euthanized after radiograph revealed snowflake pattern in lungs.
Gross Pathology: Lungs had nodular surface and were very firm (mineralized) on cut section.
Laboratory Results: Within normal limits.
Contributor's Diagnosis and Comments: Lung, bronchiectasis, diffuse, chronic, severe with mineralized bronchiolar plugs and hyperplasia of bronchiolar glands.
This striking lesion resembles that seen in humans with defects in mucociliary transport (such as cystic fibrosis). Eosinophils and smooth muscle hypertrophy are not major features of this case, as would be expected with classic feline asthma. However, intraluminal mucous plugs and bronchiolar gland hyperplasia are characteristic of feline asthma. No other tissues were available for histologic examination from this animal. Special stains for organisms were negative.
AFIP Diagnosis: Lung: Bronchiectasis and bronchiolectasis, diffuse, severe, with bronchiolar plugs, mild bronchiolar gland hyperplasia, and mild neutrophilic, histiocytic, and eosinophilic bronchiolitis, domestic shorthair, feline.
Conference Note: Bronchiectasis is defined as permanent, abnormal dilatation of bronchi. It occurs most frequently as an acquired lesion secondary to some form of bronchitis or bronchopneumonia. A severe suppurative bronchitis damages and weakens the bronchial wall which leads to pooling of exudates in the bronchial lumen. Inflammatory processes in more distal airways and alveoli contribute to lower airway obstruction and atelectasis. The loss of alveolar tissue leads to traction on the wall of airways during inspiration which contributes to airway expansion. The bronchitis may be of infectious or allergic etiology, secondary to aspiration or another abnormality such as immotile cilia syndrome.
The participants discussed the terms "asthma" and "chronic bronchitis" as they apply to the cat. While these conditions are ideally clinically distinct entities, in reality, they often overlap. Feline asthma should be characterized by paroxysmal episodes of dyspnea. The age of onset is variable, but young adults are commonly affected. There is often an identifiable precipitating event and signs of respiratory distress should resolve rapidly with administration of bronchodilators. Between episodes of dyspnea, radiographic changes are mild. Chronic bronchitis, on the other hand, is a progressive disease that usually affects middle-aged to older cats and is associated with constant bronchial pattern densities radiographically. Some cats develop bronchitis secondary to, or in addition to, asthma.
Contributor: Division of Comparative Medicine, Department of Pathology, Johns Hopkins University, Baltimore, MD 21205.
1. Moise NS, Spaulding GL: Feline bronchial asthma: Pathogenesis, pathophysiology, diagnostic, and therapeutic considerations. Comp Cont Ed 3(12):1091-1102, 1981.
2. Dye JA: Feline bronchopulmonary disease. Vet Clin Of North America 22(5), 1187-1201, 1992.
3. Jubb KVF, Kennedy PC, Palmer N (eds): Pathology of Domestic Animals. Academic Press, 4th ed., Vol. 2, pp. 573-574, 1993.
International Veterinary Pathology Slide Bank:
Laser disc frame #1827, 2549, 2709, 5695.

Case IV - ND1 (AFIP 2547367)

Signalment: Adult mink.
History: No clinical history available.
Gross Pathology: Bilateral diffuse interstitial pneumonia, prominent diffuse pulmonary congestion.
Laboratory Results: Positive fluorescent antibody test for canine distemper.
Contributor's Diagnosis and Comments: Lung: Pneumonia, interstitial, severe, diffuse, acute, with numerous intranuclear and intracytoplasmic inclusion bodies.
Canine distemper is a pansystemic disease of numerous mammalian species caused by a paramyxovirus, genus morbillivirus. It is a common cause of production losses in the ranched mink industry. Acute interstitial pneumonia is frequently the most striking gross lesion.
Microscopically, sections of lung show prominent diffuse thickening of the pulmonary interstitium due to an infiltrate of mixed inflammatory cells, proteinic material, and blood-filled alveolar capillaries. Alveolar spaces are frequently compressed and contain increased numbers of pulmonary macrophages, sloughed pneumocytes and seroproteinaceous material. Numerous intranuclear and intracytoplasmic inclusion bodies are present within bronchiolar epithelial cells, pneumocytes and macrophages. Occasional syncytial cells are present within alveoli. Pulmonary tissue is diffusely congested.
AFIP Diagnosis: Lung: Pneumonia, bronchointerstitial, subacute, diffuse, moderate, with type II pneumocyte hyperplasia, syncytia, and intranuclear and eosinophilic intracytoplasmic inclusion bodies, mink, mustelid.
Conference Note: The conference participants agreed with the contributor's diagnosis and comments. Canine distemper virus (CDV) is a common pathogen in dogs, other canids, mustelids, procyonids, and viverrids. Recently, major outbreaks of canine distemper have occurred in javelinas (collared peccaries) in the United States, and in big cats in Africa and North America.
Contributor: North Dakota State University, Department of Veterinary & Microbiological Sciences, Fargo, ND 58102.
1. Appel MJG, et al: Canine distemper epizootic in lions, tigers and leopards in North America, J Vet Diag Invest 6:277-288, 1994.
2. Domingo M, et al: Pathologic and immunocytochemical studies of morbillivirus infection in striped dolphins (Stenella coeruleoalba). Vet Pathol 29:1-10, 1992.
3. Kennedy S, et al: Histopathological and immunocytochemical studies of distemper in harbor porpoises. Vet Pathol 28:1-7, 1991.
4. Jubb KVF, Kennedy PC, Palmer N (eds): Pathology of Domestic Animal, Academic Press, 4th ed., Vol. 2, pp. 617-624, 1993.
International Veterinary Pathology Slide Bank: None.
Lance Batey
Captain, VC, USA
Registry of Veterinary Pathology*
Department of Veterinary Pathology
Armed Forces Institute of Pathology
(202)782-2615; DSN: 662-2615
* The American Veterinary Medical Association and the American College of Veterinary Pathologists are co-sponsors of the Registry of Veterinary Pathology. The C.L. Davis Foundation also provides substantial support for the Registry.
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