Patient Information

Age: 1 year
Gender: Intact Female
Breed: Llewellin Setter
Weight: 35 pounds

History

Patient presented in May 2024 by her breeders/hunting trainers for routine bloodwork prior to going to her new home. She was asymptomatic. Azotemia was detected on this bloodwork. The following diagnostics were performed at that time:

CBC: Lymphocytes 5.8K (H), all else normal

Chemistry: BUN 59mg/dL (H), Creat 2.1mg/dL (H), Albumin 2.6g/dL (L); all else normal

SDMA: 10μg/dL (WNL)

4DX: all negative

Fecal: No parasites found

In-house UA: Proteinuria (100mg/dL) and suspected cocci with low USG (1.015)

1 week later:

Recheck CBC : lymphocytes WNL, mild regenerative anemia (RBCs 5.43M/μL)

Recheck Chemistry: Creat 1.9mg/dL (H), BUN 41mg/dL, Amylase 2003 (H)

Recheck SDMA: 21μg/dL (H)

Lepto PCR: negative

Blood Pressure: Normal

Urinalysis to Lab: Proteinuria (3+), trace hematuria with 6-10 RBCs/HPF, pH 5.5 (L), USG 1.014 (L)

Cystatin B: 290ng/mL (H)

Urine Culture and Sensitivity: No growth

Patient was started on Enrofloxacin while awaiting urine culture results.

These diagnostics all suggested kidney dysfunction/injury without infection and abdominal ultrasound was recommended.

Abdominal ultrasound

Kidneys:

Both kidneys have normal size (Lt/Rt = 5.4/5.7cm ) and normal shape with coarse moderately hyperechoic renal cortices which are disproportionately large. There is moderate loss of the corticomedullary junction distinction. There is a mild amount of pyelectasia in both kidneys (Lt/Rt - 2.0/1.8mm)

Lymph Nodes:
The medial iliac lymph nodes (Lt/Rt - 0.8/0.9cm) and mesenteric lymph nodes (up to 0.9cm depth) are mildly enlarged with rounded shape having homogenous hypoechoic echogenicity.

Differentials

Kidneys - the findings are moderate - DDX:
a) Chronic nonspecific change - Chronic glomerulonephritis vs. amyloidosis, chronic interstitial nephritis, chronic nephritis.
b) Renal Dysplasia
c) Acute renal failure/Nephritis (infectious, GN, toxic, etc.) vs. Acute-on-Chronic renal failure
d) Lymphosarcoma (not suspected)
d) Pyelonephritis

Pyelectasia - the findings are mild - DDX:
a) IV fluid administration
b) Pyelonephritis and ureteritis
c) Increased diuresis caused by renal insufficiency or other condition
d) Toxin
e) Infectious (leptospira, etc)
f) Post-renal obstruction / Bladder distention
g) Diuresis

Lymph nodes - the findings are mild - DDx: likely secondary to juvenile age/reactive vs. infection vs. IBD vs. unlikely neoplasia

Recommendations

Recommend monitoring renal parameters and managing chronic kidney disease per IRIS guidelines
Recommend testing for Lyme disease and Leptospirosis
Consider obtaining renal biopsy for histopathology at time of ovariohysterectomy

In her new home she transitioned from the high protein performance diet she had been fed during her hunting training to Royal Canin Renal Support.

Change of Ownership

Due to the patient’s underlying kidney disease and primary concern for renal dysplasia, she was no longer a good fit for her planned home, so instead, in August of 2024, she went to live with her sonographer, Dr. Adams, who had a soft spot for her sweet disposition…. whoops!
In her new home she transitioned from the high protein performance diet she had been fed during her hunting training to Royal Canin Renal Support.

Additional Diagnostics

August 2024:
CBC: WNL
Chem: BUN 38mg/dL, Creat 1.9mg/dL, Amylase 1529 (H)SDMA: 17.1 (H)
T4: WNL
UA: USG 1.006, 2+ protein, trace bloodUPC: 1.1 (High)

October 2024 (about 6 weeks after transition to renal diet, pre-op):
CBC: WNL
Chem: BUN 23 (WNL), Creat 1.5mg/dL (WNL), Amylase 1424 (H)
SDMA: 24.1 (H)
PT/PTT: WNL

An ovariohysterectomy was performed in October 2024 and a small renal biopsy was obtained at the time for histopathology

Renal Biopsy Results

Diagnosis

Kidney: Primitive glomeruli, mild lymphoplasmacytic interstitial nephritis and mild interstitial fibrosis

Comments

There are a few glomeruli in the sample and the majority appear to be immature (primitive). Primitive glomeruli is one of the features associated with renal dysplasia. However, the sample is very small and other features that can be identified with renal dysplasia (e.g. metanephric ducts, undifferentiated mesenchyme, atypical tubular epithelium and metaplasia) are not identified. Sample size may hinder a more complete interpretation and I can't rule out other underlying renal abnormalities, but renal dysplasia remains a strong consideration. There is also mild interstitial fibrosis and non-specific chronic inflammation. Another pathologist was consulted on this case.

There is no evidence of infectious disease, necrosis, glomerulosclerosis, amyloidosis or neoplasia. Changes should be interpreted in light of clinical history and findings.

Microscopic description

Kidney: The submitted tissue is examined whole. The sample consists of renal cortex. Nine glomeruli are identified in the sample. The majority of these have distention of Bowman's space and a shrunken glomerulus. The dilated Bowman's space contains clear space and rarely mineral. In some of these, capillaries are indistinct and are lined by prominent peripheral nuclei. The interstitium has a few irregular bands of fibrous connective tissue with low numbers of lymphocytes and plasma cells. Rare interstitial tubules are mildly dilated and lined by attenuated cuboidal epithelium.

After further discussion with the pathologist on this case it was clarified that these “primitive glomeruli” would actually be diagnosed as presumptive "glomerulocystic atrophy". These cystic changes with small (atrophied) glomeruli could be seen in a number of diseases including glomerulocystic disease, renal injury (+/- nephritis), obstructive disease and could even be an incidental finding if this change affects a minority of the kidney and it's not associated with other renal abnormalities/disease.

Outcome

Though a definitive diagnosis of renal dysplasia was not reached from the renal biopsy in this case, the patient will be treated as such given her age, labwork, sonographic abnormalities, and biopsy findings which had many of the findings often seen with renal dysplasia.

The patient, now named Millie, is being treated and monitored according to IRIS guidelines (Stage 2, proteinuric, normotensive). Currently only a diet change has been necessary with noted improvement in BUN and Creatinine after transitioning her food. She remains asymptomatic.

Despite falling asleep during her ultrasound and falsely leading Dr. Adams to believe that she is a very calm and relaxed dog, when she is not snuggling on the couch she is now enjoying tearing through her house and chewing on all of her children’s toys.

Discussion

Renal dysplasia is a disorganized development of the renal parenchyma and is often hereditary. It can occur in many breeds and can have onset of clinic signs in dogs as young as 4 weeks and up to more than 5 years. Sonographically, the appearance of the kidneys can be different depending on the severity of the disease, however it is generally characterized by small size, irregular shape, and decreased corticomedullary distinction, and diffusely hyperechoic echogenicity in both the medulla and cortex. Pyelectasia is sometimes seen. Sonographic changes can be similar in other chronic kidney diseases. Renal biopsy is therefore required for definitive diagnosis, but renal dysplasia should always be a top differential in a young dog with renal insufficiency and abnormal kidneys on ultrasound. Prognosis varies depending on the severity of the disease, however the disease is irreversible and progressive. Treatment is geared toward recognizing progression and treating based on IRIS guidelines. (http://www.iris-kidney.com/guidelines/)

Mattoon, J. S., Sellon, R. K., & Berry, C. R. (2020). Small Animal Diagnostic Ultrasound (4th ed.). Elsevier.

Hoskins JD: Pediatric Renal Disease. Western Veterinary Conference Proceedings 2004

Special thanks to Dr. Minch and Dr. O’Dair and the rest of the staff at West Creek Animal Clinic and to Dr. Cordero-Aponte at Eastern Vet Path for their collaboration on this case