Necropsy Report

Caitlyn Lennon - Western

V:50 I:4 Cases/Abstracts 1st Place

NECROPSY REPORT

Pet’s Name:        Patient X

Sex:                    Castrated male

Age:                    14 years

Species:              Canine

Weight:               26 lbs       

HISTORY 

Patient presented for evaluation after sliding down the stairs. A grade III/IV heart murmur, laxity of left stifle, moderate obesity, and significant periodontal disease was appreciated. Radiographs revealed mild cardiomegaly, mild left atrial enlargement, an otherwise unremarkable geriatric thorax (mild bronchointerstitial pattern), joint effusion in the left stifle, and mild DJD of the left tarsus. Pre-operative bloodwork revealed mild hyperalbuminemia, elevated ALP, and thrombocytosis. A lateral suture repair was performed the next day. Patient became hypotensive during surgery, but an increase in the fluid rate improved it slightly. At 11:20am the day after surgery the patient had a temperature of 104.5, was panting, had tacky mucous membranes, and was 6-7% dehydrated. His temperature decreased to 101.7 at 1pm after therapy initiated. By 8pm the temperature had increased to 103.1. The next day the patient was found deceased in his cage at 6:45am and his body was placed in the freezer at 12pm.

GROSS EXAMINATION

The animal submitted for necropsy is Patient X, a castrated male terrier mix canine.

Integumentary System:

The carcass has a body condition score of 4/5 with prominent fat stores. An oval mass was found in the right inguinal region, measuring 2.5cm by 1.5cm, and consisted of adipose tissue (lipoma). There was marked hyperemia of the skin in the inguinal region. No other significant lesions were observed in the skin or subcutaneous tissues. 

Musculoskeletal System:

The right hip joint was opened and revealed mild fibrillation, roughening, and erosion of the head of the femur, consistent with mild degenerative joint disease. A 10cm long incision was noted on the lateral aspect of the left stifle region (Figure 3). Staples were removed and sutured layers were incised, revealing strong, nonabsorbable sutures extending from the lateral fabella to the cranial aspect of the tibial crest, extracapsular to the stifle joint (Figure 4). This is consistent with a lateral suture repair technique for a rupture of the cranial cruciate ligament. The stifle joint was opened and no gross lesions were appreciated (Figure 4). The left tarsal joint was also opened and no gross lesions were revealed.

Gross Diagnosis:

1)     Mild degenerative joint disease of the right hip joint

2)     Lateral suture repair surgery of the left stifle

3)     Grossly normal left stifle and tarsal joints

FIgure 3 Figure 4 

Digestive System and Pancreas:

No significant gross lesions are noted in the oral cavity or esophagus. The stomach contains a small amount of brown liquid, but does not contain any food particles (Figure 5). Areas of the small intestines are moderately red (postmortem) and appear grossly normal when opened (Figure 6). The pancreas appears grossly normal and no inflammation, necrosis, or masses are noted.

Gross Diagnosis:

Grossly normal oral cavity, esophagus, intestinal tract, and pancreas

 Figure 5Figure 6 

Liver:

The liver has a mild reticular pattern with moderate, multifocal areas of congestion, causing some of the edges to be rounded (Figure 7). There is oozing of blood on the cut surface consistent with congestion. There is no sign of inflammation, necrosis, or masses. The gallbladder contains a significant amount of dark, green bile consistent with the patient not eating without any evidence of stones or inflammation. The bile duct was found to be patent and the gallbladder was easily expressed.

Gross Diagnosis:

1)     Chronic passive congestion in the liver

2)     Grossly normal gallbladder

FIgure 7 

Spleen:

There is a grossly normal, contracted spleen. There were two multifocal nodules 1 cm in diameter consistent with age.

Gross Diagnosis: Nodular splenic hyperplasia  

Cardiopulmonary System:

The lungs contain multiple dark, red areas consistent with atelectasis and congestion. There is no evidence of pleural or pericardial effusion. The right side of the heart appears to be slightly distended. The apex of the heart appears mildly rounded (Figure 8). When opened, all four chambers of the heart appeared to be dilated. The tricuspid and mitral valves were thickened with myxomatous degeneration (Figure 9). White discoloration of the endocardial surface in the right and left atria is consistent with jet lesions from valvular regurgitation.

Gross Diagnosis:

1)     Pulmonary congestion and atelectasis

2)     Endocardiosis with dilation of all heart chambers

Figure 8  Figure 9  Urogenital System:

The right kidney has a normal size and shape with some areas of vascular congestion. The cut surface shows mild, diffuse tubular mineralization consistent with chronic renal disease (Figure 10-right). The left kidney has a normal size and shape. The cut surface reveals a mildly irregular, pitted cortex, some extension of the medulla into the cortex, and areas of multifocal tubular mineralization consistent with chronic renal disease (Figure 10-left). Both ureters were identified and connected to the dorsal aspect of the bladder. The bladder has a moderate amount of cloudy (postmortem) urine. A 1mm dark, circular stone was found (Figure 11). The bladder mucosa appeared grossly normal.

Gross Diagnosis:

1)     Chronic renal disease

2)     Bladder stone

Figure 10Figure 11

Adrenal Glands and Thyroid Glands:

No significant gross lesions are noted in the adrenal and/or thyroid glands. Both sets of glands appear to be of normal size and conformation with no nodules or masses noted.

Gross Diagnosis: Grossly normal adrenals and thyroid glands

Brain:

No significant gross lesions are noted on the surface of the brain (Figure 12).

Gross Diagnosis: Grossly normal brain

Figure 12 

HISTOPATHOLOGY

PENDING

COMMENTS AND CONCLUSIONS:

The gross lesions present in this animal do not suggest a definitive cause of death. Histopathology may be helpful in suggesting a pathogenesis for the reason of death in this case. However, chronic, gross lesions were identified that may help in identifying the factor that may have caused death.

The most dramatic findings in this case included valvular endocardiosis of the mitral and tricuspid valves and chronic renal changes. Valvular endocardiosis is a disease that accompanies increasing age in dogs and is a cause of heart failure in some cases. This disease involves the degradation of the collagen fibers in the valves. The valve most commonly affected is the mitral valve, followed by the tricuspid valve. This disease may cause the valves to fail and blood to regurgitate into the atria of the heart, causing white streaks on the endocardium known as jet lesions. The regurgitation may also lead to dilation of the atria and insufficient pumping of blood¹.  The changes in the kidneys included tubular mineralization, which suggests that the kidneys were working hard over a long period of time to try to compensate for the degeneration of the tubules. These tubules are very important in excreting harmful waste products such as urea and if the tubules are compromised these waste products may accumulate in the blood causing a toxicosis known as uremia¹.

The heart murmur and radiographic findings of the heart support the evidence found in the gross necropsy of valvular endocardiosis. Although these changes could have led to death, there was no gross evidence of congestive heart failure, including pleural effusion or ascites. The chronic changes in the kidney may have been severe enough to cause uremia. However, it was not noted that any evidence of azotemia existed on the pre-operative bloodwork or that the patient had any clinical signs of renal failure. There was no evidence grossly that the stifle joint or the surgical site was infected, leading to sepsis and death. It is known that anesthesia can suppress the cardiovascular system and decrease glomerular filtration rate (GFR), especially in geriatric dogs and cats². Considering this patient suffered from hypotension during surgery, this may have contributed to a more significant decrease in GFR and cardiac output. This may have complicated the existing kidney and heart problems in this patient. Pending histopathology results will help in interpreting the gross findings and suggesting a cause of death in this patient as no definitive cause can be identified from the gross lesions.

Pathologist:

                   Caitlyn Lennon BS, pending DVM

                   Veterinary Student

References

1. Pathologic Basis of Veterinary Disease. McGavin M D and Zachary J F, 5th ed, Mosby Press, 2011. ISBN: 978-0-323-07533-6

2. Hughes, JML. Anaesthesia for the geriatric dog and cat. Ir Vet J. 2008; 61(6) 380-387.