Abstract
Hepatic copper accumulation is assessed qualitatively via histopathology, and hepatic copper concentration is measured quantitatively. Laparoscopic biopsy provides samples adequate for histopathology; however, its suitability for copper quantification in cats remains unclear. Liver tissue samples from 19 cats undergoing laparoscopic liver biopsy were evaluated for hepatic copper score and concentration. Copper scores were determined by a board-certified pathologist using rhodanine-stained sections. Hepatic copper concentrations were determined using atomic absorption spectrometry, and the rhodanine-positive pixel ratio was calculated from histological images using ImageJ. Copper-associated hepatopathy was identified in three cats: two with a score of 4 and one with a score of 5. Seven cats demonstrated cholangiohepatitis (scores 0–3). The hepatic copper score was significantly correlated with copper concentration in the 19 cats (Spearman’s r=0.757, P<0.001). Rhodanine-positive pixel ratio also correlated with copper concentration (Spearman’s r=0.668, P<0.01). Therefore, laparoscopic biopsy provides feline liver tissue feasible for qualitative and quantitative copper analysis. The liver rhodanine-positive pixel ratio offers a useful quantitative alternative when hepatic copper concentration cannot be measured in cats.
Keywords: cholangitis/cholangiohepatitis, copper accumulation, feline, hepatopathy, rhodanine
INTRODUCTION
Feline primary copper-associated hepatopathy, though uncommon [9], has recently been documented in several cases across Japan and other countries [2, 3, 8, 15, 20]. In addition to primary hepatic copper accumulation, secondary deposition may occur in cats with cholangitis/cholangiohepatitis associated with chronic cholestasis. Excessive copper within hepatocytes contributes to liver necrosis, chronic inflammation, and fibrosis, ultimately progressing to liver failure. Consequently, qualitative and quantitative assessment of hepatic copper is critical for evaluating disease progression and guiding treatment strategies in affected cats [24].
Accurate diagnosis heavily relies on histopathological examination with copper staining and measurement of hepatic copper concentration, which necessitates multiple large liver biopsies (20–40 mg each) [7, 23, 25,26,27]. While ultrasound-guided needle biopsy often yields insufficient tissue, laparoscopic liver biopsy enables safe acquisition of larger specimens from different hepatic lobes in cats and dogs using 5-mm cup biopsy forceps [7, 11,12,13]. Reflecting this advantage, the American College of Veterinary Internal Medicine consensus statement recommends laparoscopic liver biopsy for canine chronic hepatitis, including copper-associated chronic hepatitis [23], suggesting potential applicability in felines with copper-associated hepatopathy.
A semiquantitative scoring system ranging from 0 to 5, based on histopathological copper-stained sections, has been used to qualitatively assess copper content in liver biopsy samples from dogs [6]. Atomic absorption spectroscopy of dried liver remains the gold standard [23]; however, digital quantification of histologic slides stained with rhodanine using a positive-pixel algorithm, correlates strongly with hepatic copper concentrations [5]. However, comparable data for cats remain limited, particularly regarding samples obtained via laparoscopic cup biopsy forceps. Addressing this gap, the present study aimed to qualitatively and quantitatively evaluate hepatic copper in cats undergoing laparoscopic liver biopsy.
MATERIALS AND METHODS
Cases and the laparoscopic liver biopsy method
Nineteen pet cats with suspected diffuse hepatobiliary disease referred to the Nihon University Animal Medical Center between 2020 and 2025 were included in the analysis. Laparoscopic liver biopsies were performed on all cats by a laparoscopist (MS) for definitive diagnosis. The cats were pre-medicated with atropine sulfate (0.04 mg/kg, SC; Atropine Sulfate Injection; NIPRO, Osaka, Japan) and butorphanol (0.2 mg/kg, IV; Vetorphale; Meiji Animal Health Co., Kumamoto, Japan). Anesthesia was induced with propofol (10 mg/kg, IV; PropoFlo; Zoetis, Parsippany, NJ, USA) and maintained with 2.0% isoflurane (ds isoflurane; Bussan Animal Health Co.; Osaka, Japan) in 100% oxygen. Analgesia was induced with buprenorphine (0.02 mg/kg, IV; Lepetan; Otsuka Pharmaceutical Co., Tokyo, Japan) or tramadol (0.2 mg/kg, SC; Tramal; Nippon Shinyaku Co., Kyoto, Japan). Samples were collected from the left lateral lobe using a left-sided approach and from the right medial lobe using a right-sided approach. The cats were positioned in lateral recumbency, and the abdominal cavity was insufflated with carbon dioxide (CO2) to 8 mmHg. Two trocar cannulas were placed, and the abdominal cavity was explored; the liver was visualized with a laparoscope (5 mm in diameter, 0-degree; Karl Storz; Baden-Wurttemberg, Germany). Liver samples were obtained from selected liver lobes under laparoscopy using 5-mm cup biopsy forceps (Karl Storz; Fig. 1A) for histopathological assessment, bacterial culture, and measurement of copper concentration. Each cat was administered cefovecin sulfate (8 mg/kg, SC; Convenia; Zoetis) after subcutaneous tissue and skin closure.
Fig. 1.
Laparoscopic findings during liver biopsy in a cat. Liver samples were obtained using a 5-mm cup biopsy instrument (A, Case 8). Bleeding was minimal at the biopsy sites (arrows) following liver biopsy from different liver lobes (B, Case 19).
Histopathological qualitative evaluation: hepatic copper score
Liver tissues were fixed in 10% neutral buffered formalin. If multiple samples were collected, one section was prepared from each sample. Paraffin-embedded specimens were sectioned at 3.5 µm and stained with hematoxylin and eosin, as well as rhodanine. An American College of Veterinary Pathologists board-certified pathologist (YK) histopathologically diagnosed the specimens and evaluated histological copper scores on a scale of 0–5 (Fig. 2) [5, 25]. If several copper scores were present for a single case, the highest copper score was used.
Fig. 2.
Histopathological findings of rhodanine-stained liver sections of cats. (A) Hepatic copper score of 0 in Case 2 (hepatic copper concentration: 144 µg/g dwl). (B) Hepatic copper score of 5 in Case 19. Hepatocytes are extensively stained deep red-orange, which is consistent with copper granules (hepatic copper concentration: 4,932 µg/g dwl).
Quantitative measurement: hepatic and serum copper concentration
The specimens were immediately frozen and stored at −80°C until analysis. Hepatic copper concentrations (expressed as µg/g of dry weight liver [dwl]) were measured using atomic absorption spectroscopy at a commercial laboratory (SRL Inc., Tokyo, Japan). In two cats, the serum collected before and after laparoscopy was immediately frozen and stored at −80°C until analysis. Serum copper concentrations were measured by colorimetry (FUJIFILM VET Systems Inc., Tokyo, Japan) and expressed in µg/dL.
Analysis using digital scanning of rhodanine-stained liver biopsy specimens
The same sections assessed for hepatic copper scoring were used for digital copper quantification (Fig. 3). Rhodanine-positive granules were quantified as the hepatic rhodanine-positive pixel ratio, calculated by dividing the number of copper-positive pixels by the total histological pixels across multiple tissue sections from each case. These sections were digitally scanned using a virtual slide system (Olympus Soft Imaging Solutions GmbH, Olympus, Tokyo, Japan), and background areas were excluded in ImageJ (version 1.54; National Institutes of Health, Bethesda, MD, USA). Copper granules in liver sections were selected using the “Color Threshold” command in ImageJ to quantify the color of individual copper granules using the following hue (H), saturation (S), and brightness (B) ranges: H 0–10 and 191–255, S 21–255, and B 54–255. The “Color Threshold” settings were defined based on preliminary analyses conducted prior to the main study. Fine-tuning was performed via visual inspection, confirming the inclusion of all copper granule pixels and the exclusion of other pixels. For each case, if rhodanine-positive pixel ratios were calculated on multiple slides, the median value was selected as the representative value for analysis.
Fig. 3.
Analysis of digitally scanned rhodanine-stained liver biopsy specimens from a cat. (A) Digital microscopic image of total histological pixel calculation in a liver section. The rhodanine-stained liver section was scanned digitally using a virtual slide system, and the background area was excluded in ImageJ. (B) Digital microscopic image of copper-positive pixel calculation in the liver section. (C) Copper granules in the liver section were selected using the “Color Threshold” command in ImageJ. (D) The hepatic rhodanine-positive pixel ratio was calculated as the ratio of the copper-positive pixel area (Area 2) to the total histological pixel area (Area 1).
Statistical analysis
Statistical analysis was performed using R (version 4.3.3, R Core Team, Vienna, Austria). Normality of the hepatic copper concentration, rhodanine-positive pixel ratio, and hepatic copper score was assessed using the Shapiro–Wilk test and visual inspection of histograms. These data did not follow a normal distribution. For each case, when rhodanine-positive pixel ratios were calculated from multiple slides, the median value was defined as the histopathological copper concentration for that case. Correlations between elements were determined using Spearman’s rank correlation coefficient. All differences were considered significant at P<0.05.
RESULTS
Case population
The following cat breeds were included: mixed domestic shorthair (n=14), Munchkin (n=2), Scottish Fold (n=1), Abyssinian (n=1), and Russian Blue (n=1) (Table 1). The mean age (10 neutered males and nine neutered females) was 7.8 years (range, 1.9–14.4 years), and the mean body weight was 4.1 kg (range, 2.2–6.0 kg). Serum alanine aminotransferase (ALT) activity was elevated in 17 cats (range, 98–749 U/L), whereas five demonstrated hyperbilirubinemia. Bacterial cultures of the specimens were negative in all cats. Histopathological diagnoses included cholangiohepatitis (n=7), copper-associated hepatopathy (n=3), primary hypoplasia of the portal vein (n=3), hepatic lipidosis (n=2), hepatic lymphoma (n=1), and no remarkable findings (n=3). In the seven cats with cholangiohepatitis, inflammation was mild (n=3), moderate (n=3), or severe (n=1). Two of the three cats with copper-associated hepatopathy exhibited hepatic lipidosis (Case 17) and chronic hepatitis (Case 19), respectively.
Table 1. Clinical information of 19 cats undergoing laparoscopic liver biopsy.
| Case no. | Breed | Sex | Age (years) | BW (kg) | ALT (U/L) | T-BIL (mg/dL) | Histopathological diagnosis |
|---|---|---|---|---|---|---|---|
| 1 | Mixed | MC | 6.3 | 5.3 | 194 | 0.1 | Hepatic lipidosis |
| 2 | Munchkin | MC | 6.8 | 5.6 | 259 | 0.0 | No finding |
| 3 | Mixed | FS | 14.4 | 3.8 | 180 | 0.2 | Primary hypoplasia of the portal vein |
| 4 | Mixed | FS | 2.8 | 3.6 | 696 | 0.2 | Primary hypoplasia of the portal vein |
| 5 | Mixed | FS | 6.3 | 3.9 | 243 | 0.2 | Cholangiohepatitis (mild) |
| 6 | Mixed | MC | 3.6 | 3.9 | 304 | 0.8 | No finding |
| 7 | Scottish Fold | FS | 5.0 | 4.1 | 254 | 0.1 | Primary hypoplasia of the portal vein |
| 8 | Mixed | MC | 7.3 | 6.0 | 391 | 4.2 | Cholangiohepatitis (severe) |
| 9 | Mixed | MC | 10.9 | 5.2 | 646 | 0.1 | Cholangiohepatitis (moderate) |
| 10 | Abyssinian | FS | 13.8 | 2.2 | 26 | 0.0 | No finding |
| 11 | Mixed | FS | 10.1 | 3.6 | 306 | 0.1 | Cholangiohepatitis (mild) |
| 12 | Mixed | MC | 7.2 | 4.2 | 749 | 1.3 | Cholangiohepatitis (mild) |
| 13 | Mixed | MC | 10.8 | 4.4 | 98 | 0.3 | Hepatic lipidosis |
| 14 | Mixed | FS | 8.3 | 3.3 | 362 | 6.2 | Hepatic lymphoma |
| 15 | Russian Blue | MC | 11.3 | 4.8 | 391 | 3.3 | Cholangiohepatitis (moderate) |
| 16 | Munchkin | FS | 13.0 | 3.1 | 330 | 0.2 | Cholangiohepatitis (moderate) |
| 17 | Mixed | MC | 5.5 | 5.2 | 303 | 0.2 | Copper-associated hepatopathy |
| 18 | Mixed | MC | 3.0 | 2.7 | 42 | 0.1 | Copper-associated hepatopathy |
| 19 | Mixed | FS | 1.9 | 3.5 | 358 | 0.2 | Copper-associated hepatopathy |
BW, body weight; ALT, alanine aminotransferase (reference range, 22–84 U/L); T-BIL, total bilirubin (reference range, 0–0.4 mg/dL); MC, male-castrated; FS, female-spayed.
Laparoscopic liver biopsy
Anesthesia remained stable during biopsy, and bleeding was minimal (Fig. 1B). No intraoperative complications, such as those reported in previous studies [1, 18], were observed in the cats, and recovery from anesthesia was smooth. Two cats (Cases 18 and 19) with severe copper accumulation died suddenly within a few days of discharge. Serum copper concentrations were measured in these cats using frozen-stored serum samples obtained before and after laparoscopic liver biopsy. Consequently, serum copper concentrations in both cats were significantly elevated following liver biopsy (Table 2).
Table 2. Serum copper concentrations in two cats with hepatic copper accumulation before and after laparoscopic liver biopsy.
| Case no. | Serum copper concentration (μg/dL) | |
|---|---|---|
| Before liver biopsy | After liver biopsy | |
| 18 | 195 | 330 |
| 19 | 245 | 888 |
Serum copper concentration (reference range, 50–107 μg/dL).
Hepatic copper score and concentration
The number of liver tissue samples obtained from the left lateral lobe or the right medial lobe was determined based on the condition of each case. The median number of rhodanine-stained tissue sections assessed for hepatic copper scoring was 5 (range: 2–12 sections). Hepatic copper scores in the 19 cats are presented in Table 3, and the median hepatic copper concentration was 449 µg/g dwl (range: 109–4,932 µg/g dwl). A significant correlation was identified between hepatic copper score and hepatic copper concentration (r=0.757, P<0.001; Fig. 4).
Table 3. Hepatic copper score and concentration in 19 cats.
| Case no. | Sampling hepatic lobe | Hepatic copper score | Hepatic copper concentration (mg/g of dry weight liver [dwl]) |
|---|---|---|---|
| 1 | LLL | 0 | 109 |
| 2 | LLL | 0 | 144 |
| 3 | LLL | 0 | 166 |
| 4 | LLL | 0 | 186 |
| 5 | LLL | 0 | 192 |
| 6 | RML | 0 | 275 |
| 7 | RML | 0 | 436 |
| 8 | RML | 0 | 456 |
| 9 | RML | 0 | 544 |
| 10 | RML | 0 | 655 |
| 11 | RML | 1 | 347 |
| 12 | RML | 1 | 436 |
| 13 | LLL | 1 | 449 |
| 14 | RML | 1 | 513 |
| 15 | LLL | 2 | 1,086 |
| 16 | LLL | 3 | 982 |
| 17 | RML | 4 | 3,175 |
| 18 | LLL | 4 | 2,036 |
| 19 | RML | 5 | 4,932 |
LLL, left lateral lobe; RML, right medial lobe.
Fig. 4.
Correlation between hepatic copper concentrations and hepatic copper scores for liver specimens in 19 cats (Spearman’s r=0.757, P<0.001).
Hepatic rhodanine-positive pixel ratio
Digital histological imaging confirmed rhodanine-positive granules in 15 of 19 cats, and the rhodanine-positive pixel ratio was calculated in hepatic tissue from these 15 cats. A significant correlation was identified between the hepatic rhodanine-positive pixel ratio and copper concentration (r=0.668, P<0.01; Fig. 5).
Fig. 5.
Correlation between hepatic copper concentrations and hepatic rhodanine-positive pixel ratio for liver specimens in 19 cats (Spearman’s r=0.668, P<0.01).
DISCUSSION
In the present study, multiple liver tissue samples were obtained from 19 cats, on which histopathological, bacteriological, and hepatic copper concentration measurements were performed. Thus, collecting samples laparoscopically from multiple liver lobes may aid in evaluating copper accumulation throughout the liver. Liver biopsy is routinely performed for histopathological diagnosis of feline liver diseases [28]. Laparoscopic 5-mm cup biopsy forceps facilitate the collection of liver samples in dogs and cats, providing sufficient tissue for histopathological examination [7, 12,13,14] and hepatic copper concentration measurement in dogs [13]. However, no study has confirmed whether hepatic copper concentrations can be measured in laparoscopically obtained feline tissue using 5-mm cup biopsy forceps [7].
Following laparoscopic liver biopsy in the present study, 3 of 19 cats were suspected of having copper-associated hepatopathy based on histopathological copper accumulation (score 4–5) and a remarkable increase in hepatic copper concentration (2,036–4,932 µg/g dwl). However, since we did not conduct ATP7B gene mutation testing, whether these three cats had primary copper-associated hepatopathy remains undetermined. Primary copper-associated hepatopathy is rare in cats, for which detailed information is not included in the World Small Animal Veterinary Association Liver Standardization Group’s classification of hepatic disorders for feline liver diseases [22]. One study reported primary copper-associated hepatopathy in 11 of 100 cats with hepatobiliary disease, based on markedly elevated hepatic copper concentrations (>700 µg/g dwl) and copper accumulation, in the absence of additional cholestatic disorders [9]. Additionally, a Japanese study of intraoperative liver tissue specimens from 54 cats identified four suspected cases of copper-associated hepatopathy, three of which carried single-nucleotide variants in ATP7B, which is associated with copper metabolism [2].
Two cats suddenly died a few days post-laparoscopic liver biopsy (Cases 18 and 19). In these cats, bleeding at the biopsy sites was minimal, and their conditions remained stable until discharge, but serum copper concentrations following liver biopsy were significantly higher than those before. Accordingly, acute copper toxicosis attributed to copper release from the liver into the bloodstream following a laparoscopic liver biopsy suggests a contribution to death in these cases, though the true cause of death remains unknown since an autopsy was unavailable. In a previous study, a cat with copper-associated hepatopathy (liver copper concentration 4,074 μg/g dwl) died 4 days post-exploratory laparotomy and liver biopsy [8]. In sheep, copper toxicosis is common; copper is released into the blood when the liver’s copper storage capacity is exceeded [4], which induces acute hemolysis with anemia, hemoglobinuria, jaundice, and death within 1 to 2 days. Additionally, a young Dalmatian with copper-associated hepatitis was euthanized due to excessive vomiting that began within 24 hr of a wedge liver biopsy via laparotomy; both hepatic and serum copper concentrations were elevated [17]. Other young Dalmatian died suddenly at home 1 day after laparoscopy [16], and serum copper concentration was elevated at 246 μg/dL (reference range: 66–130 μg/dL).
In this study, a veterinary pathologist assessed histological copper scoring on rhodanine-stained sections, which was positive in 9 of 19 cats (47%). Three cats exhibited severe hepatic copper accumulation (scores 4 and 5), suggesting primary copper-associated hepatopathy. Six cats exhibited mild-to-moderate hepatic copper accumulation (scores 1–3), including four with cholangiohepatitis, which can, in turn, cause secondary hepatic copper accumulation due to cholestasis and hyperbilirubinemia [9]. Rhodanine staining was negative in 10 of 19 cats (score 0), including three with cholangiohepatitis. Hepatic copper score showed no correlation with ALT levels or hyperbilirubinemia in cats with copper-associated hepatopathy and cholangiohepatitis; therefore, inferring liver copper accumulation solely from blood examinations may be challenging. Nonetheless, cats with severe hepatic copper accumulation may exhibit elevated serum copper concentrations, as shown in Cases 18 and 19 in the present study. By comparison, in a previous report, rhodanine staining was positive in 13 of 121 archived formalin-fixed, paraffin-embedded feline liver specimens obtained through necropsy or surgical biopsy [27]. Hepatic copper scores in these cats were 1, 2, 3, and 4 in nine, one, two, and one cats, respectively; a score of 5 was not observed.
Hepatic copper concentration significantly correlated with hepatic copper score in the present study (Spearman’s r=0.757, P<0.001). Hepatic copper concentrations exceeded 700 µg/g dwl in five cats: three (Cases 17, 18, and 19; scores 4 and 5) with copper-associated hepatopathy, and two (Cases 15, 16; scores 2 and 3) with cholangiohepatitis. In four cats with hepatic copper score 1, hepatic copper concentrations ranged from 347 to 513 µg/g dwl, and two cats had cholangiohepatitis. In 10 cats (score 0), hepatic copper concentrations ranged from 109 to 655 μg/g dwl. The normal range for feline hepatic copper concentration is 150–180 μg/g dwl [19]; nonetheless, only 3/19 cats had values within this range. Hepatic copper concentrations >700 μg/g dwl have been reported in cats with presumed primary copper-associated hepatopathy [9]. Hepatic copper concentrations in cats and dogs are often measured using atomic absorption spectroscopy and inductively coupled plasma mass spectrometry using archived formalin-fixed paraffin-embedded liver specimens and fresh liver tissues [13, 23, 26]. In 121 such cat liver specimens, hepatic copper scores based on rhodanine staining and hepatic copper concentrations measured using atomic absorption spectroscopy were positively correlated [27].
The hepatic rhodanine-positive pixel ratio was determined in liver biopsy samples from 15 of 19 cats, including 10 with a hepatic copper score of zero. Additionally, the hepatic rhodanine-positive pixel ratio significantly correlated with hepatic copper concentration. Digital histological imaging is effective in assessing hepatic copper concentration in dogs, cats, and ferrets with hepatobiliary disease [5, 9, 21]. Currently, no commercial laboratory in Japan accepts hepatic copper concentration measurements using atomic absorption spectroscopy. Therefore, this digital histological imaging method might be useful for cats with suspected copper-associated hepatopathy. Hepatic copper concentrations may vary among biopsy samples, even within the same individual dog with copper-associated chronic hepatitis [10]. Furthermore, lower copper accumulation is associated with architectural remodeling, such as nodular regeneration, parenchymal loss, or fibrosis [5].
In conclusion, our findings demonstrate that hepatic copper score and concentration can be assessed using feline liver tissue samples obtained via laparoscopic biopsy. Additionally, the hepatic rhodanine-positive pixel ratio, calculated using ImageJ, is a simple, cost-effective, and quantitative method for cats when hepatic copper concentration cannot be measured, offering an alternative approach to atomic absorption spectroscopy.
CONFLICT OF INTEREST
The authors declare no conflicts of interest.
REFERENCES
- 1.Anderson SJ, Fransson BA. 2019. Complications related to entry techniques for laparoscopy in 159 dogs and cats. Vet Surg 48: 707–714. doi: 10.1111/vsu.13230 [DOI] [PubMed] [Google Scholar]
- 2.Asada H, Chambers JK, Kojima M, Goto-Koshino Y, Nakagawa T, Yokoyama N, Tsuboi M, Uchida K, Tsujimoto H, Ohno K. 2020. Variations in ATP7B in cats with primary copper-associated hepatopathy. J Feline Med Surg 22: 753–759. doi: 10.1177/1098612X19884763 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Asada H, Kojima M, Nagahara T, Goto-Koshino Y, Chambers JK, Nakagawa T, Yokoyama N, Uchida K, Tsujimoto H, Ohno K. 2019. Hepatic copper accumulation in a young cat with familial variations in the ATP7B gene. J Vet Intern Med 33: 874–878. doi: 10.1111/jvim.15399 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Borobia M, Villanueva-Saz S, Ruiz de Arcaute M, Fernández A, Verde MT, González JM, Navarro T, Benito AA, Arnal JL, De Las Heras M, Ortín A. 2022. Copper poisoning, a deadly hazard for sheep. Animals (Basel) 12: 2388. doi: 10.3390/ani12182388 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Center SA, McDonough SP, Bogdanovic L. 2013. Digital image analysis of rhodanine-stained liver biopsy specimens for calculation of hepatic copper concentrations in dogs. Am J Vet Res 74: 1474–1480. doi: 10.2460/ajvr.74.12.1474 [DOI] [PubMed] [Google Scholar]
- 6.Dirksen K, Fieten H. 2017. Canine copper-associated hepatitis. Vet Clin North Am Small Anim Pract 47: 631–644. doi: 10.1016/j.cvsm.2016.11.011 [DOI] [PubMed] [Google Scholar]
- 7.Dobberstein REA, Brisson BA, Foster RA, Monteith G, Larose PC, Rankovic A, Verbrugghe A, Shoveller AK. 2024. Comparison of the diagnostic yield of 3 and 5 mm laparoscopic liver biopsy forceps in cats. Vet Surg 53: 302–310. doi: 10.1111/vsu.14049 [DOI] [PubMed] [Google Scholar]
- 8.Haynes JS, Wade PR. 1995. Hepatopathy associated with excessive hepatic copper in a Siamese cat. Vet Pathol 32: 427–429. doi: 10.1177/030098589503200414 [DOI] [PubMed] [Google Scholar]
- 9.Hurwitz BM, Center SA, Randolph JF, McDonough SP, Warner KL, Hazelwood KS, Chiapella AM, Mazzei MJ, Leavey K, Acquaviva AE, Lindsay MM, Sanders L, Pintar J. 2014. Presumed primary and secondary hepatic copper accumulation in cats. J Am Vet Med Assoc 244: 68–77. doi: 10.2460/javma.244.1.68 [DOI] [PubMed] [Google Scholar]
- 10.Johnston AN, Center SA, McDonough SP, Warner KL. 2009. Influence of biopsy specimen size, tissue fixation, and assay variation on copper, iron, and zinc concentrations in canine livers. Am J Vet Res 70: 1502–1511. doi: 10.2460/ajvr.70.12.1502 [DOI] [PubMed] [Google Scholar]
- 11.Kemp SD, Zimmerman KL, Panciera DL, Monroe WE, Leib MS, Lanz OI. 2015. A comparison of liver sampling techniques in dogs. J Vet Intern Med 29: 51–57. doi: 10.1111/jvim.12508 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Kimbrell TL, Milovancev M, Olsen R, Löhr CV. 2018. Comparison of diagnostic accuracy of laparoscopic 3 mm and 5 mm cup biopsies to wedge biopsies of canine livers. J Vet Intern Med 32: 701–706. doi: 10.1111/jvim.15054 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.Larose PC, Brisson BA, Foster RA, Monteith G. 2024. Comparing 3 mm and 5 mm laparoscopic liver biopsy samples in dogs. Vet Surg 53: 742–753. doi: 10.1111/vsu.14006 [DOI] [PubMed] [Google Scholar]
- 14.Lidbury JA. 2017. Getting the most out of liver biopsy. Vet Clin North Am Small Anim Pract 47: 569–583. doi: 10.1016/j.cvsm.2016.11.007 [DOI] [PubMed] [Google Scholar]
- 15.Meertens NM, Bokhove CA, van den Ingh TSGAM. 2005. Copper-associated chronic hepatitis and cirrhosis in a European Shorthair cat. Vet Pathol 42: 97–100. doi: 10.1354/vp.42-1-97 [DOI] [PubMed] [Google Scholar]
- 16.Nakaichi M, Iseri T, Horikirizono H, Komine M, Itoh H, Sunahara H, Nemoto Y, Itamoto K, Tani K. 2021. Copper-associated hepatitis in a young Dalmatian dog in Japan. J Vet Med Sci 83: 911–915. doi: 10.1292/jvms.21-0061 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.Noaker LJ, Washabau RJ, Detrisac CJ, Heldmann E, Hendrick MJ. 1999. Copper associated acute hepatic failure in a dog. J Am Vet Med Assoc 214: 1502–1506, 1495. doi: 10.2460/javma.1999.214.10.1502 [DOI] [PubMed] [Google Scholar]
- 18.Petre SL, McClaran JK, Bergman PJ, Monette S. 2012. Safety and efficacy of laparoscopic hepatic biopsy in dogs: 80 cases (2004–2009). J Am Vet Med Assoc 240: 181–185. doi: 10.2460/javma.240.2.181 [DOI] [PubMed] [Google Scholar]
- 19.Puls R. 1988. Mineral Levels in Animal Health. Diagnostic Data, p. 70. Sherpa International, Clearbrook. [Google Scholar]
- 20.Recchia BK, Stokol T, Goto-Koshino Y, Ohno K, Miner KD. 2023. Diagnosis, management and genetic analysis of a cat with primary copper hepatopathy. JFMS Open Rep 9: 20551169231177275. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 21.Richard JN, Graham JE, Center SA, Garner MM, Reavill DR. 2022. Hepatic copper accumulates in ferrets with and without hepatobiliary disease. Am J Vet Res 83: 371–380. doi: 10.2460/ajvr.21.08.0131 [DOI] [PubMed] [Google Scholar]
- 22.Van den Ingh TSGAM, Winkle TV, Cullen JM, Charles JA, Desmet VJ. 2006. Morphological classification of parenchymal disorders of the canine and feline liver. pp. 85–101. In: Standards for Clinical and Histological Diagnosis of Canine and Feline Liver Diseases, 1st ed. (Rothuizen J, Bunch SE, Charles JA, Cullen JM., Desmet VJ, Szatmari V, Twedt DC, Van den Ingh TSGAM, Winkle TV, Washabau RJ eds.), Saunders Elsevier, Philadelphia. [Google Scholar]
- 23.Webster CRL, Center SA, Cullen JM, Penninck DG, Richter KP, Twedt DC, Watson PJ. 2019. ACVIM consensus statement on the diagnosis and treatment of chronic hepatitis in dogs. J Vet Intern Med 33: 1173–1200. doi: 10.1111/jvim.15467 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 24.Whittemore JC, Newkirk KM, Reel DM, Reed A. 2012. Hepatic copper and iron accumulation and histologic findings in 104 feline liver biopsies. J Vet Diagn Invest 24: 656–661. doi: 10.1177/1040638712445765 [DOI] [PubMed] [Google Scholar]
- 25.Yamkate P, Gold RM, Twedt DC, Suchodolski JS, Steiner JM, Lidbury JA. 2022. Assessment of the intracellular distribution of copper in liver specimens from cats. PLoS One 17: e0264003. doi: 10.1371/journal.pone.0264003 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 26.Yamkate P, Funke S, Steiger K, Gold RM, Lidbury JA, Karst U, Steiner JM. 2023. Quantitative bioimaging of copper in frozen liver specimens from cats using laser ablation-inductively coupled plasma-mass spectrometry. J Feline Med Surg 25: X231186919. doi: 10.1177/1098612X231186919 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 27.Yamkate P, Gold RM, Xenoulis PG, Steiger K, Twedt DC, Suchodolski JS, Steiner JM, Lidbury JA. 2021. Assessment of copper accumulation in archived liver specimens from cats. J Feline Med Surg 23: 526–533. doi: 10.1177/1098612X20961350 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 28.Zawie DA, Garvey MS. 1984. Feline hepatic disease. Vet Clin North Am Small Anim Pract 14: 1201–1230. doi: 10.1016/S0195-5616(84)50154-5 [DOI] [PubMed] [Google Scholar]