Relationship between race start characteristics and risk of catastrophic injury in thoroughbreds: 78 cases (1992)

OBJECTIVE

To investigate relationships of several racehorse characteristics and race conditions with risk of a catastrophic musculoskeletal injury (CMI) resulting in euthanasia in Thoroughbreds during racing in California in 1992.

DESIGN

Retrospective longitudinal study.

ANIMALS

Thoroughbreds that incurred CMI during racing and all California race entrants in 1992.

PROCEDURE

Necropsy records were reviewed, and race start information was obtained. Incidence risk of CMI/1,000 race entrants was estimated. Relationships between CMI during racing and race-meet, entrant age and sex, race type and length, and racing surface type and condition were evaluated by use of logistic regression.

RESULTS

Incidence risk of CMI was 1.7/1,000 entrants. A higher risk of CMI was found at 2 fair race-meets, with incidence risks of 4.9 and 5.5/1,000 entrants. Risk of injury in male horses was 1.7 times greater than that in female horses, and influence of age on risk depended on race type. Risk of injury for horses 2 to 5 years old was two times greater for claiming horses than for maiden horses. Race length or racing surface type (dirt vs turf) or condition (fast, muddy, yielding) were not significantly associated with risk of CMI.

CLINICAL IMPLICATIONS

Incidence of CMI was similar among 12 of 14 major and fair race-meets and among various race lengths and racing surface types and conditions, whereas incidence of CMI was influenced by entrant age and sex as well as race type. Investigators should consider controlling for age and sex, race-meet, and race type whenever possible in studies of risk of CMI.

Mitotane (o,p'-DDD) resistance in a dog with pituitary-dependent hyperadrenocorticism and phaeochromocytoma

A dog was presented with a 2 year history of polyuria and polydipsia due to pituitary-dependent hyperadrenocorticism. A low-dose dexamethasone suppression test and measurement of plasma ACTH concentration confirmed the diagnosis. Treatment was instituted with mitotane at 44 mg/kg/day and then 88 mg/kg/d without complete resolution of signs. The dog collapsed with signs consistent with liver disease and was euthanased. Necropsy revealed a phaeochromocytoma of the left adrenal medulla with extensive metastases to the liver. A chromophobe adenoma of the pars intermedia of the pituitary was found.

Inclusion body disease in two captive Australian pythons (Morelia spilota variegata and Morelia spilota spilota)

Two captive Australian pythons, one carpet and one diamond python, presented with signs of central nervous system dysfunction. The carpet python was agitated. Its head was tilting and it was incoordinated and had convulsions. It was treated with antibiotics and anthelmintics but was eventually euthanased after failing to respond to therapy. The diamond python had flaccid paralysis of the caudal half. It was not treated and became disoriented and died. Hepatocytes from both pythons contained irregular 2 to 10 micron eosinophilic intracytoplasmic inclusion bodies. The brain of the diamond python was not available for examination. Occasional neurones in the carpet python brain contained similar inclusion bodies and other changes suggestive of viral infection. The clinical signs and histopathological findings in both pythons were consistent with boid inclusion body disease.

[Survey of the existing housing situation for cats (Felis catus) in German-Swiss animal shelters]

This study investigated the current situation of cat husbandry in the animal shelters of german-speaking Switzerland. In 1993, Swiss-german animal shelters occupied just over 5000 housing spaces. Additionally, there was one quarantine space per eight housing spaces. During the summer, which is the season of highest demand, the requirement for housing and quarantine spaces was inadequate. In 1993, approximately 30,000 cats were housed in Swiss-german animal shelters. About four fifths of all entries were boarding cats and the rest were homeless cats. In 1993, about three-quarters of all homeless cats were rehoused with new owners. About a tenth of the remaining cats were reclaimed by their owners. Another tenth of the animals were euthanatized. 63 animal shelters kept cats mainly in group housing enclosures. 15 preferred single/pair boxes, whereas 22 animal shelters used both types of housing. This study shows that more housing and quarantine spaces are needed and should be built for the summer season, to avoid the inadequate housing capacities in Swiss-german animal shelters.

Scintigraphic assessment of distal extremity perfusion in 17 patients

To assess the role of scintigraphic evaluation of distal limb perfusion, the medical records and scintigraphic perfusion images of 17 animals (8 dogs, 2 cats, 2 calves, 4 birds and 1 ferret) with clinical signs of distal limb ischemia were examined retrospectively. Images were obtained at 5 and 10 minutes following injection of 99mTc-MDP, or 99mTc-DTPA. The initial scintigraphic diagnoses of 17 animals included complete ischemia (8/17), partially reduced perfusion (5/17), and normal to increased perfusion (4/17). In 4 of the animals with partially reduced perfusion, follow-up scans indicated progression to complete ischemia (1/4) or normal to increased perfusion (3/4). Nine of 17 animals had a final scintigraphic diagnosis of complete distal limb ischemia, and these animals were either euthanized (5/9) or had limb amputation (4/9). A final diagnosis of complete ischemia was supported with either repeat scanning (3/10), continued clinical observation (6/10) and/or pathological examination (10/10). Clinical signs of ischemia resolved in all (7/17) animals with increased or normal perfusion on their final scan. Scintigraphy provided a safe and noninvasive assessment of distal limb perfusion, which corresponded with clinical outcome.

Working with laboratory animals: general principles and practical considerations

Laboratory animals play an indispensable role in research discovery and technological advances, and they will continue to yield basic, exciting, and prodigious information that can enrich the future of people and other animals. For both ethical and scientific reasons, all-individuals whose work requires the use of laboratory animals must take the time to conduct a thorough review of the literature to determine what animal models are available and which are the most relevant, and they must learn and understand the uniqueness of the selected species, breed, and strain. Scientists have the privilege, but not the right, to use animals as experimental subjects. This privilege must not be abused. Therefore, it is imperative that before working with any laboratory animal, you know your "subject."

Esophageal/gastric adenocarcinoma in a dog

A nine-year-old, intact female, mixed-breed dog was presented with a history of chronic regurgitation and weight loss. Endoscopy and contrast radiography confirmed the presence of a distal esophageal mass. The dog was euthanized, and histopathological diagnosis of the mass was an esophageal/gastric adenocarcinoma.

Lifespan and lesions in genetically heterogeneous (four-way cross) mice: a new model for aging research

Genetically heterogeneous animal models provide many advantages for research on aging but have been used infrequently. We present here lifespan and lesion data from a study of mice bred as a cross between (AKR/J x DBA/2J)F1 females and (C57BL/6J x SJL/J)F1 males. In such a four-way cross population, each mouse is genetically unique, but replicate populations of essentially similar genetic structure can be generated quickly, at low cost, and of arbitrary size from commercially available, genetically stable hybrid parents. We employed a protocol in which mice judged to be severely ill were euthanatized to obtain tissue in optimal condition for necropsy, and we were able to infer a likely cause of illness in 42 of 44 animals. Malignant lymphoma, including at least four histopathologically distinct subtypes, was the most common cause and was also a frequent incidental finding in mice dying of other causes. Neoplastic disease, benign or malignant, was the sole or a contributing cause of illness in 90% of the mice for which a cause could plausibly be assigned. A wide range of lethal and nonlethal degenerative lesions was also noted. The coefficient of variation for lifespan in these genetically heterogeneous mice was 26%, similar to that seen in analyses of recombinant inbred mouse lines. Baseline lifespan and pathology data on four-way cross mice is a useful prelude to the exploitation of this rodent model in tests of genetic and mechanistic hypotheses about aging.